eastern treatment plant upgrade: information in · pdf fileeastern treatment plant upgrade:...

Eastern Treatment Plant Upgrade: Information in Support of a Works Approval Application

Table of contents

Eastern Treatment Plant Upgrade: Information in Support of a Works Approval Application Melbourne Water i

Executive Summary 3

Glossary 15

1. Eastern Treatment Plant – An Introduction 21

1.1 The Eastern Treatment Plant 21 1.2 How the treatment process works 24 1.3 Ongoing research and monitoring program 30 1.4 Working with the community 32 1.5 Background to the Current Works Approval WA48124 32 1.6 The Purpose of this Document 37

2. Why Upgrade The ETP? 38

2.1 The Receiving Environment 38 2.2 Overview of Marine Studies History 39 2.3 Studies Prior to 1996 39 2.4 The CSIRO Effluent Management Study – 1996-99 42 2.5 Studies from 2001 Onwards 48 2.6 What the Studies Have Told Us 54 2.7 Key Conclusions 85

3. Strategic Context for Decision Making 88

3.1 Climate Change & Water Resources Outlook for the Central Region 88 3.2 Streamflows and Impacts on Waterways Diverters 91 3.3 Sewage Flow Trends for Melbourne 93 3.4 Sewage Inflows to the Eastern Treatment Plant 94 3.5 Declining Loads to the Environment 99 3.6 Potential Recycling Outlook 100 3.7 Policy and Regulatory Aspects 108 3.8 Community Expectations 119 3.9 Key Conclusions 125

4. Improving Outcomes Through Treatment 128

4.1 Treatment Objectives 128 4.2 Treatment Process Concepts 130 4.3 Tertiary Technology Trials 133

ii Melbourne Water

4.4 Treatment investigation findings 135 4.5 Treatment outcomes 142 4.6 Treatment Option Assessment and Short-listing 150 4.7 Description of Preferred Treatment Option 154 4.8 Environmental Outcomes of Advanced Tertiary Treatment 159 4.9 Key Conclusions 161

5. Extending the Outfall 163

5.1 The Current Outfall Arrangements 163 5.2 Extending the Outfall 164 5.3 Construction Aspects 165 5.4 Environmental, Planning and Cultural Heritage Aspects of Construction 172 5.5 Approvals 174 5.6 Outcomes for the Marine Environment 177 5.7 Key Conclusions 182

6. Assessing The Options 184

6.1 Triple Bottom Line Assessment 184 6.2 Basic Assumptions 187 6.3 Description of the scenarios 188 6.4 Discussion and Assessment 192 6.5 Assessment Outcomes 225 6.6 Conclusions 231

7. Proposed path forward 236

7.1 Proposed Works 236 7.2 Residual mixing zone requirements 236 7.3 Timelines 238 7.4 Environmental Monitoring Program 238

Appendices 240

1. Mixing Zones 2. Discharge Aesthetics & Amenity Summary 2009 3. 2004-2007 Monitoring Report (CSIRO et.al.) 4. Hydrodynamic Modelling Report 2009 (GHD) 5. Concept design of Advanced Tertiary Treatment Plant (Black & Veatch/KBR) 6. Outfall Concepts & Updated Costing 2009 (GHD)

Eastern Treatment Plant Upgrade: Information in Support of a Works Approval Application Melbourne Water 3

Overview

Climate change, new treatment technology and a desire to reduce impacts on the natural environment are reshaping how we deal with sewage. Traditionally, the community has seen sewage as a waste product that represents the end of a process, not as a product available to provide further benefits. Treatment methods have improved over time, but past sewage management practices have had negative impacts when effluent is discharged into the marine environment. The Eastern Treatment Plant (ETP) represented best-practice when it was built in 1975. Considerable investment by Melbourne Water has improved its performance since then, as new technologies became available. As part of continual improvement in line with meeting the objectives of the State Environment and Protection Policy (Waters of Victoria), referred to through ETP’s EPA Victoria discharge licence, Melbourne Water plans a major upgrade of ETP from secondary to an advanced tertiary level of sewage treatment. A Works Approval for an upgrade has previously been granted by EPA Victoria, but Melbourne Water is now seeking approval for a revised upgrade approach based on: • Findings from technology trials of alternative and improved advanced tertiary

treatment methods that provide significantly improved outcomes • Success of implementation of ammonia reduction works under the existing Works

Approval • The updated strategic environment and declining flows and loads to the

environment • An outlook to increase recycling of treated effluent over time to further build on

the improvements for the marine environment offered by the propose treatment upgrade.

The main features of Melbourne Water’s preferred approach as set out in this revised Works Approval application are: • Upgrading ETP to include an Advanced Tertiary Treatment Plant by late-2012,

based on Ozone and Biological Media Filtration treatment, coupled with ultraviolet disinfection, at an estimated P50 (nominal) capital cost of $380 million (previously estimated to be around $330 million in equivalent dollars)

Executive Summary

4 Melbourne Water

• In view of the reduced marine impacts from this treatment method, to not extend the existing outfall beyond Boags Rocks.

It is important to note that, while the P50 capital cost of the proposed advanced tertiary treatment upgrade is around $50 million more (in equivalent dollars) than the tertiary treatment upgrade previously announced, the total cost of works included in the proposed new Works Approval is considerably less than originally required, because around $400 million will be saved through not building an outfall extension. This document is prepared in support of a Works Approval Application for the upgrade of the Eastern Treatment Plant setting out the strategic context, current impacts, options for upgrading the ETP, and the role of the outfall at Boags Rocks in relation to impacts on the marine environment.

Background

The existing EPA Victoria Works Approval for the upgrade of the Eastern Treatment Plant was issued on 28 November 2003. It provided for Melbourne Water to implement the following elements to address marine discharge impacts at the Boags Rocks outfall: • Upgrading ETP by implementing tertiary filtration and enhanced disinfection to

achieve a Class A standard effluent quality • Ammonia reduction in a modified secondary treatment process • Relocating the discharge point offshore by a minimum of 2 km.


In August 2005, the tertiary upgrade and outfall extension were deferred by agreement with EPA Victoria pending further scientific studies and investigations – including further hydrodynamic modelling and the Eastern Water Recycling Proposal feasibility study. Melbourne Water has, however, continued to proceed with the staged implementation of ammonia reduction works from the original Works Approval, specifically: • Works enabling commencement of operation in ammonia reduction mode were

completed and commissioned in 2007 • Additional secondary aeration tanks to cater for future load growth, and provide

robustness of the treatment process to ensure continued compliance with licence conditions into the future, are currently under construction for completion in 2009/10.

Melbourne Water reported on the outcomes of the scientific studies to EPA Victoria in September 2006. In October 2006, the Victorian Government confirmed that ETP would be upgraded to treat wastewater to Class A standard by 2012, as confirmed in Our Water, Our Future – The Next Stage of the Government’s Water Plan, June 2007. Melbourne Water acknowledged the need to plan for the best method of implementing the upgrade while also waiting for clarification of the outlook for recycling schemes that would reduce volumes requiring disposal. In November 2006, it put forward a proposed path to making final decisions in 2009 regarding: • The need for an outfall extension, given potential for environmental gains through

better treatment and more recycling over time • The best method of tertiary treatment, with the preferred technology to be

finalised through: - Design and construction of a $10M tertiary technology trial facility in 2007 - Trials during 2008-09 on standard tertiary filtration options, and more

advanced forms of tertiary treatment to better address impacts at the shoreline discharge point and produce a high quality product to facilitate increased recycling

- A decision in 2009, based on the results of the trials, on whether or not this advanced treatment technology will form the basis for the tertiary upgrade

Results of technology trials

In March 2009 Melbourne Water completed 12 months of technology trials. These trials included a wide range of tertiary and advanced treatment processes.

6 Melbourne Water

The key objective of these trials was to explore the most efficient way of achieving a treated effluent quality that addressed marine discharge impacts as required by the State Environment Protection Policy (SEPP), and produce water suitable for a broader range of recycling purposes. The trials were extremely successful. They highlighted that significant advances have been achieved in treatment technology since the existing Works Approval was issued in 2003. In Melbourne Water’s view, the results warranted a reassessment of the intended overall package of works to be undertaken as part of the upgrade. These results are critical in underpinning the basis of this revised Works Approval Application. Specifically, the trials have demonstrated that Ozone-Biological Media Filtration treatment can be implemented efficiently as part of the upgrade to better address residual aesthetic and ecological impacts of the effluent discharge at Boags Rocks. The preferred advanced tertiary process for ETP selected on the basis of the trials consists of Ozonation and Biological Media Filtration (BMF), followed by Ultraviolet (UV) and Chlorine disinfection. It was found that the advanced tertiary process offered greater benefits than conventional tertiary filtration approaches previously envisaged in the existing Works Approval, given ETP’s unique water quality characteristics, scale and discharge point. Advanced tertiary treatment has the ability to reduce colour (which together with suspended solids, foam, and turbidity are key contributors to plume visibility), odour and residual foam formation potential. Water clarity and plume visibility issues are addressed. The process will also further reduce the ammonia concentration and toxicity of the effluent discharged. The proposed advanced tertiary treatment process also offers all of the other benefits of a typical tertiary filtration process, including: • The elimination of litter • Reducing turbidity and suspended solids, oil and grease, and biological foam • Further reducing the risk to recreational users of the marine environment via the

enhanced disinfection processes. The added benefits for the marine environment offered by the Advanced Tertiary process trains were found to be significant. The additional ammonia reduction, and barrier to potential toxicants, and improvement to the key aesthetic parameters are important features, both in terms of the receiving waters and encouraging customer acceptance and uptake in more recycled water applications.


While the initial drivers for considering this process related to the residual aesthetic impacts of a shoreline discharge, it also: • Offers significant benefits for producing fit-for-purpose recycled water for a broader

range of non-drinking applications • Supports recycling through improving customer acceptance by removing colour and

odour concerns • Further reduces ammonia to very low levels and controls effluent toxicity peaks,

with significant benefits for the marine environment • Improves downstream process efficiency (ultra-violet and chlorine disinfection

performance, or future membrane installations) hence delivering the best value for money now and into the future, as a platform for providing flexibility in the future to further enhance recycled water treatment, as needed.

Extending the outfall

The 2003 Works Approval specified a 2 kilometre extension to the existing marine outfall at Boags Rocks. This was based on the assumption that meeting the objectives of the SEPP around residual ecological and aesthetic impacts could only be reasonably achieved by upgrading the treatment process and extending the outfall. However, results of trials show that Melbourne Water’s proposed advanced tertiary treatment process can adequately address these residual marine impacts without the need to extend the outfall. The outfall extension requirement was also based on certain assumptions around what it would take to build. Extensive work has been undertaken by outfall construction experts in the years since, and a more thorough understanding of the required scope and costs is now in place. In 2002, the EPA Victoria appointed an independent Panel to carry out an assessment of the then Works Approval proposal under Section 20B of the Environment Protection Act. The Panel indicated that an outfall extension should be incorporated in the overall works package. This recommendation was made in the context of cost estimates developed in the 1990s, which suggested costs an order of magnitude lower than the more rigorously developed designs and cost plans now available. The 1990s cost estimate was derived from a very early concept based on a bottom-tow construction method comprising two pipelines which would be buried across the

8 Melbourne Water

shoreline and to at least the 5m depth contour. Beyond this a trench would be excavated in the seabed. Extensive work has been undertaken by outfall construction experts in the years since, and a thorough understanding of the required scope and costs is now in place. This work has indicated the original construction method presents significant difficulties and risks associated with constructing large pipelines through the surf zone in this high energy coastline. This method would also involve substantial disruption to the highly sensitive environmental foreshore and dunes area. This method is not considered feasible. Consequently, the construction method was changed to tunnelling. Following a detailed investigation into design, construction methodology and an updated costing taking into account a thorough assessment of current construction costs and risk, items a RANE P50 estimate of $400M was established by independent experts. The $400M cost of extending the outfall, and the impacts associated with construction, would be incurred to facilitate more extensive recovery of a small area of potential habitat for Neptunes Necklace and Bull Kelp. This area is located immediately adjacent to the discharge point. This habitat is not unique at Boags Rocks. These species and other such intertidal rocky platforms are widely found along the South East Australian coastline. Weighing up the benefit of an outfall extension against the costs associated with it, Melbourne Water believes that the environmental benefits do not justify the social and financial costs. The full triple-bottom-line analysis that has been undertaken supports this decision. In Melbourne Water’s view, the Advanced Tertiary upgrade without an outfall extension, will: • Address the aesthetic and amenity impacts in the marine environment • Improve the aesthetics of the treated water to improve its acceptability for

recycled water customers • Further reduce the ammonia concentration in the discharged effluent, and so

protect even the most ammonia sensitive species • Further reduce potential public health risks under peak wet weather flow

conditions to recreational users of beaches around Boags Rocks • Remove all litter, foam and suspended solids from the discharge • Improve the marine environment outcomes to the extent that only a very small

residual mixing zone is required, and


• Facilitate increased reuse development over time, which will continue the trend of declining flows and loads to the environment at Boags Rocks, and reinforcing the environmental gains.

An outfall extension, in addition to the Advanced Tertiary upgrade, would relocate the discharge point and increase the initial dilutions in the marine environment. Although this would have some additional benefits in terms of facilitating more extensive recovery of a small area of potential habitat for Neptune’s Necklace and Bull Kelp, as outlined above, this benefit comes at the following costs: • Capital cost of approximately $400 million • Significant construction impacts • May lessen the impetus for recycling, and • The possibility that the outfall extension may be seen as a 'stranded asset' if

recycling opportunities are fully realised over time. Therefore, it is Melbourne Water's view that construction of an outfall extension is not appropriate in this case and is demonstrably "not practicable" under the State Environment Protection Policy.

Reducing impacts on the marine environment

Melbourne Water acknowledges that the current impact of ETP on the marine environment must be improved. The treatment method it proposes represents best practice for large-scale treatment for discharges to the open marine environment. In many respects, it will be world-leading. Keeping the current nearshore discharge location will, in turn, require the retention of small residual freshwater and nutrient mixing zones, as allowed for in the State Environment Protection Policy. The benefits of the high level of treatment are reflected in the very small size of residual mixing zones - an important benefit when considered in the context of managing 40% of Melbourne’s treated wastewater. Even within the residual mixing zone, significant environmental benefits accrue from the proposed changes including resolution of aesthetic issues, reduction of the suspended solids food source for opportunistic species (which have colonised the platform area within 150m of the discharge point), major improvements to water clarity, and the toxicity impacts on the key ammonia sensitive indicator (Neptunes Necklace) are addressed.

10 Melbourne Water

The increased use of recycling into the future (made more feasible by the higher level of treatment) would build on these gains for the marine environment as freshwater volumes and nutrient loads decline further through diversion to recycling applications. This will facilitate continuous improvement and the opportunity to shrink the mixing zones even further over time. In designing its preferred approach, Melbourne Water has taken note of issues of amenity raised by recreational users in the vicinity of the discharge point. The advanced tertiary treatment process ensures better conditions for swimmers and surfers by comprehensively addressing the microbiological concerns and aesthetic issues associated with the current discharge. As mentioned earlier, the Panel assessing the original Works Approval application in 2002 indicated that an outfall extension should be incorporated in the upgrade. Melbourne Water believes material, evidence-based changes on a number of fronts require this to be reassessed. Below is a summary of how Melbourne Water’s preferred approach to the upgrade would address the key marine impacts that were to originally be managed with an outfall extension. The risk of foams/solids causing impacts at the point of discharge - The Ozone-BMF process will reduce any residual foam forming potential to a level comparable to tap water. Biological foam formers are removed by the proposed treatment. Oil and grease levels are further reduced. Solids and surfactant effects are comprehensively removed by the treatment. This will build upon the improvements that have been observed from treatment improvements in recent years. Allowing for ecosystem recovery and compliance with SEPP mixing zones requirements - The Ozone-BMF process will reduce the toxicity of the discharge at Boags Rocks through a combination of further reduced ammonia levels and a broad spectrum barrier to other potential minor toxicants. The most sensitive species for ammonia toxicity is consistently protected by the advanced tertiary process, leaving only residual freshwater effects which are addressed by a safe dilution of 20:1 for the most salinity sensitive test (scallop larval development). Hydrodynamic modelling indicates the 20:1 safe dilution is achieved within a radius of 250m from the discharge point. The small residual mixing zone is provided for in the SEPP, and even within the residual mixing zone, significant environmental benefits accrue from the proposed changes including reduction of the suspended solids food source for undesirable


opportunistic species (in particular the spionid worm Boccardia), major improvements to water clarity, and from addressing the toxicity impacts on the key macroalga indicator H. Banksii. (Neptune’s Necklace). Effects within a defined mixing zone can be expected to further decline over time as the trend towards diversions of freshwater and nutrient loads to recycling continues. Ensuring the recreational amenity of swimmers and surfers - The advanced tertiary treatment process ensures the recreational amenity of swimmers and surfers by comprehensively addressing the microbiological concerns and the aesthetic issues associated with the current discharge. Management of freshwater impacts - Complete reuse of the effluent stream will not be possible to achieve in the medium term, therefore some form of ocean discharge will remain. However, the science on freshwater impacts has been clarified by the extensive ecotoxicity testing program. The residual freshwater effects are addressed by a safe dilution of 20:1 for the most salinity sensitive test (scallop larval development), and this is achieved within a radius of 250m from the discharge point. The treated effluent flows outlook has changed significantly in the intervening years. The overall picture is now one of declining flows and loads to the environment. Successful adaptation to the uncertainties of climate change, and the drivers for increased utilisation of fit-for-purpose water resources where practicable, will continue this trend. Current plant inflows are actually around 20% lower than the outlook considered by the Panel in 2002 and this translates to lower flows to the outfall. Furthermore, the local recycling developments (see following section) have the potential to significantly enhance this.

The role of water recycling

One of the major benefits of Melbourne Water’s preferred treatment approach is increased scope for more water recycling for non-drinking purposes. The same advanced treatment process that reduces impacts on the marine environment will simultaneously broaden the potential uses of recycled water. It is also expected to increase customer acceptance of recycled water for non-drinking purposes through addressing key areas of potential customer concern.

12 Melbourne Water

Recycled water is already used in operating the Eastern Treatment Plant instead of potable water that would otherwise be required. Off-site recycled water use from ETP totalled 7.9 billion litres for 2007/08, and was supplied to the Eastern Irrigation Scheme and to South East Water customers who take Class C recycled water from various points along the South Eastern Outfall reducing discharges at Boags Rocks. In June 2009, the Minister for Water announced that investigations into two major recycling projects to use the Class A water produced at ETP (post-upgrade) had found that the cost-benefit balance made these reuse options unfeasible. Instead, the focus will be on local, cost-effective recycled water projects. In addition to the 7.9 billion litres per year of current offsite recycling, schemes that have existing approval, or approval in-principle are expected to deliver up to an additional 9.1 billion litres per year of recycling diversions, further reducing the nutrient and freshwater loads to the receiving environment. Work undertaken for South East Water has identified a range of potential projects over the next 20 years that could take the total offsite recycling up to 40 billion litres per year. These projects will continue to be investigated as work on the ETP upgrade continues. The discharge to Bass Strait will therefore need to continue for the foreseeable future, albeit with volumes reduced by from the mid 1990s levels by some 25-40%, but the significant advance in treatment technology proposed will ensure that the ongoing marine discharge impacts will be reduced to acceptable levels following completion of the advanced treatment upgrade proposed. The advanced tertiary upgrade provides a ‘future-proof’ process train that allows for later addition of ultrafiltration and reverse osmosis membranes, to further enhance recycled water treatment in the future as needed.

Conclusion

The proposal put forward in this Works Approval application is consistent with achieving continual improvement in the discharge from ETP in line with meeting the objectives of the State Environment and Protection Policy referred to through ETP’s EPA Victoria discharge licence. The SEPP requires the practicability of the proposed actions to be taken into account to ensure that the environmental benefits justify the social and financial costs. This requires consideration of the following issues: • the severity of the environmental risk in question and the environmental benefits

of removing or mitigating that risk;


• the state of knowledge of the environmental risk and options for removing or mitigating that risk;

• the availability, efficiency and suitability of options to remove or mitigate that risk; and

• the financial and social costs and benefits of removing or mitigating that risk. The Advanced Tertiary and ammonia reduction upgrades, in conjunction with ongoing recycling development, will have a significant environmental benefit. An outfall extension, in addition to the Advanced Tertiary upgrade, would also address the residual localised impacts caused by freshwater and nutrients by relocating the discharge and increasing the initial dilutions in the marine environment. However, Melbourne Water is of the view that this environmental benefit does not outweigh the financial and social costs of an outfall extension. One of the major benefits of Melbourne Water’s preferred treatment approach is scope for more water recycling. The TBL assessment has considered the options available. The TBL assessment outcomes show that scenarios which include Advanced Tertiary, but no outfall extension, have a significantly better outcome than a scenario which includes both Advanced Tertiary and an outfall extension. The TBL assessment clearly supports Melbourne Water's conclusion that an outfall extension is not practicable in the circumstances. In consideration of international best practice, it is necessary to consider the combination of treatment and disposal methods together. Long outfalls were generally built prior to implementation of treatment to either primary or secondary treatment. The advanced tertiary treatment process proposed for ETP is at the forefront of international best practice for a wastewater plant, and clearly represents best practice for discharges to the open marine environment. The treatment outcomes achieved allow for retention of a near shore discharge. In summary, significant environmental improvements will be achieved at the discharge point from implementation of advanced tertiary treatment, plus the current ammonia reduction works, plus the progressive development of recycling diversions over time.

14 Melbourne Water


ACH Coagulant used to improve solids capture and thickening processes

Advanced treatment For the application to ETP, this refers to treatment of additional aspects of the effluent quality not specifically addressed by more traditional tertiary filtration and disinfection processes, such as ammonia, colour, odour etc. The advanced treatment process technology investigated as part of the ETP Tertiary Upgrade Project is Ozonation coupled with Biological Media Filtration.

Amphipod A shrimp like crustacean

Anaerobic Biological treatment in the absence of oxygen and nitrate

Anthracite A variety of coal used as media for filtration purposes either alone or in conjunction with sand

ANZECC Australian New Zealand Environment and Conservation Council

ATTP Advanced Tertiary Treatment Plant

BMF Biological Media Filtration – A generic term for media filtration process where, due to the conditions, a fixed-film biomass population develops on the surface of the media e.g. Biological Activated Carbon (BAC)

Backwash rate The rate at which water is supplied to the media filter in the reverse direction in order to dislodge captured solids

BDOC Biodegradable Dissolved Organic Carbon

Bioaccumulation The accumulation of chemicals within an organism, due to the organism absorbing it at a greater rate than it’s excretion

Biodegradation Broken down or removed by biological processes – e.g. the processes occurring in a Biological Media Filter or the Activated Sludge process

Bioluminescence The production of light by an organism due to a chemical reaction.

Biota Collection of organisms within a region

BOD Biochemical or Biological Oxygen Demand

Chlorination The process of adding chlorine to water for disinfection purposes

Chloramination Chloramines are used for disinfection and form when chlorine is

Glossary

16 Melbourne Water

added to water which contains ammonia

Chlorophyll A The green pigment found in most plants, algae and cyanobacteria which is vital for obtaining energy from light (photosynthesis)

Class A A recycled water quality specification as defined by the Use of Reclaimed Water - Guidelines for Environmental Management, EPA Victoria

Coagulation Addition of metal salts (e.g. iron or aluminium) to change the surface charges on particulate and colloidal solids suspended in water. Fine and colloid particles are typically hydrophilic, or ‘water loving’ which tends to keep them separated and suspended in water. Coagulation chemicals change the particles to hydrophobic, or ‘water hating’, which encourages them to aggregate together into larger clusters of solids which can either be settled or filtered out of the water. Coagulation is synonymous with flocculation.

Colloidal material Very small particulate material which typically remains suspended in water and can be difficult to remove without treatment to bring it together to form larger clusters (see coagulation and flocculation).

Ct Ct (mg-min/L), which refers to the product of disinfectant chemical concentration and its contact time with water. It is a parameter used to define chemical disinfection processes. Typically greater disinfection, in terms of pathogen reduction, occurs with increasing Ct which can be achieved through variable combinations of chemical concentration and contact time (e.g. high concentration and short contact time or vice versa). Cts are different for different pathogens and chemical disinfectants, such as ozone and chlorine, and are dependent on the dose response of the specific pathogens to the specific disinfection chemicals.

DAFT Dissolved Air Floatation Thickening

DALY Disability Adjusted Life Year – used to define tolerable risk targets

DHS Department of Human Services

Disinfection byproducts Inorganic and organic compounds formed by the reaction of the disinfectant with water constituents

DOC Dissolved Organic Carbon

EHBs Effluent Holding Basins

Endocrine Disruptors Substances which influence the functioning of the endocrine system, e.g. by mimicking or blocking the action of natural hormones

Emerging contaminants of concern

Micro-contaminants such as Pharmaceuticals and Personal Care Products including active compounds in sunscreens, fragrances, antibacterial products, prescription medication and over the


counter drugs, and synthetic and natural endocrine disrupting compounds.

EBCT Empty bed contact time - time taken for effluent to flow through certain filters, e.g. BMFs

Epibiota Aquatic biota which lives on the rubble of the sea floor.

Epidemiology Study of factors affecting health and illness of populations

ETP Eastern Treatment Plant

Filter run time The filtration time between backwashes

Filtration rate A specific measurement of the flow of water passing through a filter, typically expressed for media filters as cubic meters of water per hour per square metre of filter cross-sectional area. For membranes it is typically LMH (Litres/hour per meter2 of membrane filter surface area).

Flocculation Flocculation refers to the process by which fine particulate and colloidal solids are caused to clump together into larger clusters of solids, or flocs, which may subsequently be removed by sedimentation of filtration. Flocculation is synonymous with coagulation.

Flux or Flux rate The flowrate applied to membranes represented as volume of flow per unit area of membrane per time unit, typically L/m2/h (litres per m2 of membrane area per hour).

GALO Naturally occurring bacteria which form part of the biomass in activated sludge plants (known as Gordonia Amarae like organisms) and which can cause biological foaming.

GEM Guidelines for Environmental Management

HACCP Hazard Analysis and Critical Control Point - ia systematic preventative approach most commonly used for food and pharmaceutical safety to address physical, chemical, and biological hazards as a means of prevention, rather than purely inspection of the finished product. In relation to this document the quality of treated waste water at ETP is controlled via HACCP.

Helminths Parasitic worms that live within a living host which they feed off

Infauna Aquatic biota that lives on the sand or bottom sediment.

Jar Test An experimental procedure used to compare coagulant doses in the laboratory

Lipid Small hydrophobic molecules which typically includes fats and waxes

18 Melbourne Water

Log reduction A measure of the degree of pathogen reduction, either by removal, or inactivation/kill, provided by treatment processes. Specifically, it is the log10(no. of microorganims in the feed water) – log10(no. of microorganisms in the treated water). 1 log reduction is equivalent to 90% reduction, 2 log to 99%, 3 log to 99.9%, and so on.

LOEC Lowest Observable Effect Concentration

Macroalgae Large aquatic plants that rely on photosynthesis for energy production

MF - Microfiltration A form of filtration technology involving microporous membranes. MF membrane are characterised by a pore sizing of around 0.1-0.2 micron (supplier specific).

NATA National Association of Testing Authorities

NHMRC National Health and Medical Research Council

Nitrification Biological process using a nitrifying bacteria population to reduce the ammonia present in effluent, converting it to nitrite and then to nitrate

Nitrite Chemical compound of the formula NO2-. The biological oxidation

(nitrification) of ammonia leads to nitrite which is further oxidised to nitrate.

Nitro-musk A type of synthetic musk fragrance

NOEC No Observed Effect Concentration

NTU Measurement of the turbidity of a liquid (Nephelometric Turbidity Units)

O3 Ozone, a powerful oxidant

Organochlorine pesticides Pesticides made from organic compounds containing chlorine. DDT, Aldrin and dieldrin are all organochlorine pesticides which are both persistent and toxic.

OP Organophosphate pesticides

Oxidation A process in which a substance (the oxidant) reacts with another substance and loses an electron(s) to that substance. As a result of this exchange, chemical bonds within the substance are broken. Oxidants involved in the ETP Tertiary Technology Trials include ozone and chlorine.

Ozonation Application of ozone to effluent stream

Pathogens A biological agent that causes disease


PIRVic Primary Industries Research Victoria

Polycyclic Synthetic Musk A type of synthetic musk fragrance

PPCP’s Pharmaceuticals and Personal Care Products including active compounds in sunscreens, fragrances, antibacterial products, prescription medication and over the counter drugs.

Protozoa Single celled organisms – important protozoa from a water related health perspective are Cryptosporidium and Giardia

Pt-Co Units Platinum Cobalt units used as a quantitative measure for the colour present in water. Pt-Co units are equivalent to Hazen Units and Colour Units. While other colour measurement units do exist, Pt-Co is more suitable for describing the yellow/brown colour in treated wastewater effluents.

Phytoplankton Plankton which obtains energy through photosynthesis

QMRA Quantitative Microbial Risk Assessment

Recovery The amount of water produced by the treatment process as net product compared to the amount of water filtered

SEACI South Eastern Australian Climate Initiative

Secondary Effluent Effluent that has undergone primary sedimentation and biological treatment and clarification at ETP prior to discharge into the effluent holding basins.

SEPP State Environment Protection Policy

Solids breakthrough Can occur at the end of a filter run if the capacity of the filter bed is exceeded and results in solids in the filtrate

STP Sewage Treatment Plant

Surface drogue Apparatus (usually floating) used to take measurements of currents

Surfactant Reduces surface/interfacial tension of liquids, e.g. detergents

TIE Toxicity Identification Evaluation

TSPS Tertiary Supply Pump Station

Turbidity Small particles present in effluent that make the effluent appear cloudy, due to their light scattering properties

UF - Ultrafiltration A form of filtration technology involving microporous membranes. UF membranes are characterised by a pore sizing of around 0.02 micron (supplier specific).

20 Melbourne Water

UVA Ultraviolet Absorbance. A measurement of the extent to which UV light is absorbed by compounds in water. UVA is related to UVT by an inverse logarithmic relationship.

UVT Ultraviolet Transmittance. A measurement of the degree of transmission of UV light through water (usually light at 254 nm through a 1 cm path length).

USEPA US Environmental Protection Agency

WHO World Health Organisation

Zooplankton Plankton that obtain energy through feeding off other plankton


When the Eastern Treatment Plant at Bangholme opened in 1975 it was a

world leader in the secondary treatment of sewage. The plant was the biggest

of its type in Australia when commissioned, providing a level of treatment not

used in any other Australian city. At that stage, primary treatment was the

standard treatment used in Australia and around the world.

Ongoing improvements to the plant over the years have continued to serve

the community well. However, Melbourne Water recognises that community

expectations have changed and has plans to undertake a major upgrade of

the plant over the next few years.

1.1 The Eastern Treatment Plant

The plant was designed and built to address the rapid expansion of Melbourne in the 1950s and 1960s, particularly in the south-eastern and eastern suburbs, and to relieve pressure on the Western Treatment Plant at Werribee, which was built in the late 1800s. The plant was commissioned in 1975 and was recognised as a leader in sewage treatment technology and combined with the nearshore outfall at Boags Rocks was considered best practice. The outfall to Bass Strait was seen as advantageous compared to the alternative of discharge to Port Phillip Bay, as it kept the treated effluent out of a low mixing, confined bay environment, and instead discharged to the higher mixing open ocean environment of Bass Strait at Boags Rocks. Today, Melbourne produces about 800 million litres of sewage every day, which has to be managed and treated. The Eastern Treatment Plant provides an essential public health service, processing about 41% of Melbourne's sewage each day. This serves about 1.5 million people, in Melbourne’s south-eastern and eastern suburbs. ETP is the second largest sewage treatment plant in Australia (behind Western Treatment Plant) and the largest activated sludge plant. More than 90% of the flow to ETP is domestic and commercial sewage, with industry contributing the remainder of the flow. The plant is located at Bangholme on an 1100-hectare site and is mainly bounded by the Frankston Freeway, Patterson River and Worsley Road.

1. Eastern Treatment Plant – An Introduction

22 Melbourne Water

Figure 1-1: The ETP Catchment

The plant operates under the requirements of a discharge licence issued by EPA Victoria and currently uses the activated sludge process to treat sewage to a secondary standard. The process results in biosolids, biogas and treated effluent. The key parts of the process are shown in the diagram and aerial photograph on the following pages, and described in the following paragraphs.


Figure 1-2: Schematic Outline of the treatment process

24 Melbourne Water

Figure 1-3: Aerial View of the Main treatment Area at ETP

1.2 How the treatment process works

Sewage includes everything that goes down the kitchen, laundry and bathroom sink, as well as what is flushed down the toilet. The treatment process used at Eastern Treatment Plant includes the following steps.

1.2.1 Preliminary treatment

Sewage flows by gravity to the influent pumping station. The pumps lift the sewage and discharge to a series of fine screens, which remove litter and rags. Combined pre-aeration and grit removal is then carried out. Pre-aeration of the sewage helps suppress odour, while grit removal reduces abrasion of plant equipment and facilitates the handling of the sludge.


1.2.2 Primary treatment

The flow then passes through to the primary sedimentation tanks. Most of the sewage sludge settles in these tanks and is collected from the bottom and pumped straight to the sludge digesters. Floating scum - mostly oil and grease - is collected on top of these tanks and is also pumped to the digesters.

1.2.3 Secondary treatment

In the aeration tanks the sewage has air pumped through it to create ideal conditions for oxygen loving (aerobic) microorganisms. The Eastern Treatment Plant uses a process commonly known as ‘activated sludge’ where sewage is added to a tank of microorganisms which use the organic matter (human waste) as their food and break it down into carbon dioxide and water. The flow from the aeration tanks is passed to circular sedimentation tanks for separation. The purpose of these tanks is to settle the activated sludge and produce a clarified final effluent.

1.2.4 Secondary sludge thickening

As the secondary sludge has a low solids concentration, it is thickened to minimise the volume fed to the digesters.

1.2.5 Sludge digestion and biosolids management

Digestion of primary scum and primary and secondary sludge takes place in circular tanks called digesters. In these tanks, organic material is broken down under anaerobic conditions (no oxygen), producing biogas and digested sludge. Once digestion is complete the digested sludge is pumped to the sludge drying pans. Here the sludge is dried, then harvested with heavy machinery and placed into stockpiles in the summer months. Biosolids are the treated, dried sludge produced from sewage treatment and, until recently, these have been stored onsite. This is not sustainable and we are seeking new beneficial uses for biosolids. Biosolids have been used successfully in Australia for soil conditioning and potting mixes, composting, land rehabilitation, landscaping, forestry, brick manufacture, agriculture and silviculture. Biosolids from the Eastern Treatment Plant have been used as conditioners and fertilisers by soil-blending companies.

26 Melbourne Water

1.2.6 Biogas use

Biogas from the digesters contains methane, which is used to generate electric power and heat in the power station to help meet the energy needs of the treatment process. As part of the Eastern Green Energy Project, the plant has recently been modernised to improve efficiency and increase renewable energy production.

1.2.7 Effluent screening and disinfection

Effluent from the secondary sedimentation tanks passes to the effluent holding basins. Prior to pumping to the outfall, effluent is first filtered through 3mm screens to further remove plastic or foreign matter that has survived the treatment process. The effluent is then disinfected using chlorine gas to reduce pathogenic organisms.

1.2.8 Outfall Pump Station and the South East Outfall

Treated effluent is pumped by the Outfall Pump Station along a 56 km pipeline to the South East Outfall at Boags Rocks, where it is discharged into Bass Strait under the licence conditions set by EPA Victoria. A proportion of this flow is diverted for use by the recycled water customers of South East Water and the Eastern Irrigation Scheme (operated by Water Infrastructure Group). Most sewage from the Mornington Peninsula is treated at smaller South East Water plants at Mt Martha, Boneo and Somers. These plants connect to the South East Outfall pipeline. Combined, these three plants discharge approximately 20-25 million litres a day of effluent. South East Water operates these plants under separate EPA Victoria licences.


Figure 1-4: The Coastline Near Boags Rocks

1.2.9 Water Recycling

Water recycling reduces the discharge of treated effluent to bays and the ocean and helps conserve drinking water resources. Melbourne Water has been selling ‘Class C’ recycled water from the Eastern Treatment Plant since the 1970s for use in agriculture, horticulture, vineyards, and to irrigate golf courses and sporting fields east of Melbourne. South East Water is now the recycled water retailer for these Class C applications. Water is also recycled onsite in the plant's daily operations for cleaning screens, washing down work areas, cooling, steam cleaning and irrigating landscaped areas. The Eastern Irrigation Scheme includes a small interim treatment plant (to produce Class A water from the current “Class C” ETP effluent) and distribution pipelines, and delivers about 5000 million litres of Class A recycled water each year to the Cranbourne-Five Ways area, to the south-east of Melbourne. The recycled water is

Gunnamatta Beach

SEO discharge point at Boags Rocks

St Andrews Beach

Cape Schanck

28 Melbourne Water

used for irrigation of market gardens, open space irrigation and for use through dual pipe systems in residential developments. The project commenced in April 2005 and involves a contractual partnering arrangement between Melbourne Water and Water Infrastructure Group, which manages the scheme. South East Water manages the Class A residential supply arrangements. A simplified conceptual flow balance model for 2007/08, for ETP and the discharge, is included in Figure 1-5 below.

Figure 1-5: Indicative Flow Balance for ETP and the SEO

1.2.10 Managing odour

By their nature, some of Melbourne Water's operations, including sewage treatment, generate odour. Melbourne Water aims to improve odour management so that no offensive odour is emitted from our assets. Additional odour control technology is being installed at our sewage treatment plants. At the Eastern Treatment Plant, Melbourne Water will cover tanks and channels, treat the trapped air and further improve existing odour-control facilities. A three Stage program of works is underway with commissioning of Stage 1 in June 2009. Stages 2 and 3 are due to be completed by 2012.

Influent

Eastern

Treatment Plant

Effluent

Average Flow In 310 ML/d

Biosolids

Loss to atmosphere (N + CO2)

310 ML/d pumped

Ocean Discharge 310 ML/d

Reuse along outfall ~23ML/d

SEW TP inputs ~23ML/d


1.2.11 A haven for birds

Sewage treatment plants are large all-year water bodies that provide abundant food in the form of water plants, zooplankton, aquatic insect larvae and flying insects. The Eastern Treatment Plant is home to a large native bird population, including several species of regional, state and national significance. The plant also provides valuable habitat for large numbers of migratory waders, which are covered by international treaties. Since monthly bird counts started in 1998, 177 species have been recorded at the site. This is nearly one-fifth of the bird species found in Australia. The ponds support species including the black swan, pacific black duck, blue-billed duck, grey teal and chestnut teal. The plant also provides valuable habitat for shorebirds or 'waders', including migratory species and resident species such as the black-winged stilt and masked lapwing. Native bush birds such as the superb fairy-wren, magpie-lark, red wattlebird and white-plumbed honeyeater also inhabit the plant. Migratory waders such as the sharp-tailed sandpiper and red-necked stint fly from northern Siberia, while Latham's snipe come from Japan, arriving around August and leaving for the northern hemisphere between February and May. Some travel up to 24,000 kilometres a year. In 1992 a spotted redshank was seen, which was the first sighting of the bird in Australia. Birds Australia conducts a regular census of birds at the plant and keeps track of changes in the national wading bird population. Birds Australia has a representative on the Community Liaison Committee who leads monthly surveys by volunteers. About 45 volunteers help with each count. Since bird counts began 25 years ago, the average number recorded at the plant at any one time has been 4024. But during drought, numbers have swelled beyond 7000 as the plant's lagoons, ponds and marshes provide a valuable refuge for stressed birds seeking refuge from dry conditions inland. In 2003, the survey confirmed the presence of three nationally significant birds - the Australian Painted Snipe, the Australasian Bittern and the Swift Parrot - as well as 21 species of state significance.

30 Melbourne Water

Melbourne Water and Birds Australia are developing ways to make the Eastern Treatment Plant an even better place for birdlife. This has resulted in the initial low-depth filling of an effluent holding basin, the filling of a moat on the north-west of the site, the filling of three decommissioned sludge pans and low-depth filling of another infrequently used basin.

1.2.12 Educational discovery

Melbourne Water holds open days and tours of the Eastern Treatment Plant to show interested groups - predominantly students - how sewage is treated and how effluent, biogas and biosolids are recycled. Walking tours take about 90 minutes, and teachers are given education kits based on the Victorian school curriculum. We have developed a range of education resources, including the Eastern Treatment Plant Explorer which takes users on an interactive journey around the plant. The foyer includes a display screen, which models the computer software used by operators who manage the sewage treatment process. Visitors can see how much sewage enters the plant, and how much treated effluent is pumped out.

1.3 Ongoing research and monitoring program

We closely monitor the sewage treatment process, from the moment the sewage arrives at the plant, to when it is discharged as treated effluent into Bass Strait. The Eastern Treatment Plant has been granted HACCP accreditation - it's the largest sewage plant in Australia to achieve this. HACCP (Hazard Analysis and Critical Control Point) is a quality control system that allows Melbourne Water to manage sewage treatment at a number of points along the treatment process rather than simply rely on testing the end product. The same strict procedure applies to food production. Recreational water quality is assessed through weekly E. coli. monitoring at six shoreline points, including Gunnamatta Beach, St Andrews Beach and Boags Rocks. Testing is undertaken by a NATA (National Association of Testing Authorities) accredited independent laboratory, Ecowise.


Figure 1-6: Shoreline Monitoring Points

Since February 2005, Melbourne Water has also been monitoring for Enterococci. Enterococci is recognised by the World Health Organization (WHO) as the most appropriate bacterial indicator for measuring faecal contamination. The results are published on the website (www.melbournewater.com.au) as they become available. In addition to the weekly compliance monitoring, Melbourne Water has also initiated a program to assess water quality against National Health and Medical Research Council (NHMRC) guidelines. This program involves sampling E. coli and Enterococci levels at 19 sites - 18 sites in the swim and surf (400-800m offshore) zones and at a reference site 2 kms offshore. Testing is designed to monitor long-term trends in water quality.

Figure 1-7: Swim amd Surf Zone Monitoring points

http://www.melbournewater.com.au/

32 Melbourne Water

Results are made available in Melbourne Water's Social and Environment Data, produced annually with the Sustainability Report. The programs are managed by experienced water quality scientists.

1.4 Working with the community

In addition to the independent regulation of the Eastern Treatment Plant's safety and environmental performance, Melbourne Water works closely with community and stakeholder representatives to monitor the plant's performance. A Community Liaison Committee, which includes representatives from local councils, EPA Victoria, environment groups and retail water companies, plays a vital role in the planning and management of the Eastern Treatment Plant. Melbourne Water and the Community Liaison Committee have worked with EPA Victoria to develop an Environment Improvement Plan that is a blueprint for the environmental management of the plant. It will be reviewed and updated regularly. The plan identifies the plant's impacts on the environment and specifies actions to protect and enhance the environment at and around the plant.

1.5 Background to the Current Works Approval WA48124

Following direction from EPA Victoria in 1995 to prepare a waste management strategy for Eastern Treatment Plant, Melbourne Water engaged CSIRO in 1996 to conduct a major study to: • Assess the environmental impact of effluent discharge on the marine environment

at Boags Rocks • Review effluent disposal and recycling methods for the Eastern Treatment Plant,

and • Determine the best way of reducing the impact of the effluent discharge. The aim of the project was to provide a knowledge base for the development of a sustainable strategy for future management of the plant discharge. The two-year, $1.3 million multi-disciplinary project became known as the Effluent Management Study. An essential adjunct to the study process was Melbourne Water’s involvement of the community, and this was done through the establishment of several community reference groups, which included representatives of environment groups, surf riders, the local community and Government agencies.


The data obtained from these research and investigation activities significantly increased the understanding of the complex Boags Rocks environment. The Study was completed in July 1999 when CSIRO published a final report, where the findings indicated that: • The marine environment in the vicinity of the discharge point had been affected by

ammonia and freshwater • Toxicity in effluent from Eastern Treatment Plant was primarily caused by ammonia • Ammonia could be reduced by modifications to the secondary treatment process • Effluent volumes could potentially be curtailed by increased recycling of effluent,

and minimising plant inflows • Extending the outfall would improve the environmental impact in the vicinity of the

current outfall, but would not reduce nutrients nor address broader sustainability issues

• An expanded water quality monitoring program around Boags Rocks should be implemented

The study found there was also a need to build on existing knowledge through continued monitoring and research. The community representatives supported the final report when it was published by CSIRO. In July 1999, Melbourne Water provided EPA Victoria with the CSIRO report and set out options for reducing the impact of the effluent discharge at Boags Rocks and the costs and benefits of each option. In September 1999, Melbourne Water confirmed interim actions to EPA Victoria, including undertaking a trial of ammonia reduction using one of the six aeration tanks at Eastern Treatment Plant, and developing a viable recycling scheme to increase the extent of effluent recycled from the Eastern Treatment Plant. Melbourne Water committed itself to addressing issues raised in the study, and to developing a comprehensive plan for the sustainable management of sewage from Melbourne’s eastern and south-eastern suburbs. This led to the development of the Sustainable Resource Management Plan for a proposed upgrade of the treatment plant, which was submitted in December 2001 as part of a works approval application to EPA Victoria. This plan included the following key components: • Works to reduce ammonia concentration in the treated effluent to reduce the

toxicity of the effluent and nutrient loads thereby improving the environment for marine life;

• Upgrade works to implement tertiary filtration and enhanced disinfection to facilitate recycling of treated effluent and consequently reduce the amount of

34 Melbourne Water

effluent discharged to the ocean. These upgrade works would also mitigate some of the aesthetic issues (solids, litter, reduction in biological foam formers) and the perceived public health issues at the discharge point.

The approach to incorporating tertiary filtration and enhanced disinfection in the upgrade was based on options studies and concept designs prepared throughout 2001. It was concluded that: • It is feasible to incorporate tertiary filtration for all effluent into the ETP site using

either granular media or membrane filtration • An effluent quality meeting the (then) Victorian EPA Class A reuse guidelines could

be produced using either technology and appropriate disinfection • Ultraviolet and chlorination were the most appropriate disinfection technologies • A process train based on granular media filtration was considered the most cost-

effective, given the Class A standards then proposed by EPA Victoria After further consultation with stakeholders (including a 20B conference), EPA Victoria issued a works approval for the proposed upgrade works in July 2002. The major components of works resulting from the Works Approval process are: • Upgrading the treatment plant by implementing:

- tertiary filtration and enhanced disinfection to achieve Class-A effluent quality as per EPA Victoria’s recycling guidelines

- ammonia reduction in a modified secondary treatment process to achieve a median effluent ammonia concentration of less than 5 milligrams per litre

• Relocating the final effluent discharge point offshore by a minimum of 2 km to achieve a minimum initial dilution of 50:1

Following consideration by the Victorian Civil and Administrative Tribunal and the Supreme Court of a number of third party appeals against the works approval, it was reissued with similar conditions in November 2003. Melbourne Water then commenced implementation of the ammonia reduction upgrade and completed the upgrade to the existing tanks and commissioning of the ammonia reduction process in late 2007. The construction of the additional tanks will be completed in 2009/10. Ammonia levels in the effluent now being discharged into the marine environment have been reduced by at least 85% compared with historical average ammonia concentrations. By agreement with EPA Victoria, implementation of the tertiary treatment upgrade and works to extend the ocean outfall were deferred for two years pending the outcomes of a range of investigations including additional receiving environment studies, a Quantitative Microbial Risk Assessment (QMRA), additional hydrodynamic


modelling, further assessment of the expected effects of the tertiary treatment upgrade, and any reduction in outflow resulting from recycling initiatives. Melbourne Water reported to EPA Victoria on the outcomes of these studies in September 2006. In October 2006, the Victorian Government announced that the tertiary upgrade of ETP would be completed in late 2012, as outlined in “Our Water, Our Future – The Next Stage of the Government’s Water Plan, June 2007”. In November 2006, Melbourne Water provided a report to EPA Victoria outlining the proposed path forward for final decisions in 2009 regarding: • The technology choice for the tertiary treatment upgrade • The need for an outfall extension • A timeline for completion of the upgrade by the end of 2012. The proposed path forward included: • Works to reduce ammonia in the treated effluent are continuing with Stage 1

(existing tanks process conversion) delivered in 2007 and Stage 2 (additional aeration tanks) in 2009/10

• Completion of the tertiary upgrade in late 2012, with the preferred technology to be finalised through; - Design and construction of a $10M tertiary technology trial facility in 2007. - Trials across 2008 on options for tertiary treatment to achieve both Class A

standard recycled water, and more advanced forms of treatment to more comprehensively address impacts at the shoreline discharge point,

- A mid 2008 progress report to EPA Victoria on the trials - A decision in 2009, based on the results of the trials, on whether or not this

additional advanced treatment technology will be implemented as part of the upgrade works, and how efficiencies could be achieved by integrating the advanced treatments with the other proposed upgrades

• Continued monitoring of the environment and progress on recycling opportunities • Finalise the overall works package in 2009 with respect to the preferred form of

treatment, and extension of the ocean outfall or retaining the current location. The first stage of planning for the tertiary upgrade involved design, construction and commissioning a tertiary technology trial facility at ETP across 2007. Melbourne Water commenced the 12 month Tertiary Technology Trials in February 2008 to inform, and assist in, the formulation of the design and implementation of the full-scale upgrade.

36 Melbourne Water

The trials have provided extremely valuable and essential information for assessing preferred treatment trains and scope of work for the upgrade options. The trials included a range of both tertiary and advanced treatment processes to address marine impacts and produce water suitable for a broader range of recycling purposes. The key objective of the trials was to explore the most efficient way of achieving an effluent quality to address marine discharge impacts as required by the EPAV licence for ETP, the relevant provisions of the Environment Protection Act and State Environment Protection Policies invoked by the licence. An initial 12 month period of tertiary technology trials, to determine the preferred process train for the upgrade of the treatment process has been completed and Melbourne Water now understands the benefits that the inclusion of advanced treatment technologies can offer for both the marine environment and for producing a high quality recycled water product suitable for a wide range of non potable uses. Adaptive management principles have informed the ongoing monitoring, plant operational and upgrade decisions for the ETP. The adaptive management principles that have been applied to the monitoring programs are set out in the report ‘Eastern Treatment Plant: Monitoring the Receiving Environment, Background Review and Data Analysis’ (Fox 2000). Adaptive management uses criteria tailored to detecting impacts on a regional or ecosystem basis. It takes into account the uncertain predictions of impacts, unforeseen and unforeseeable impacts (e.g. cumulative impacts), interactions among ecosystem components, and natural variability. The ANZECC/ARMCANZ Guidelines provide a framework that goes beyond compliance with single-number, necessarily conservative values, to guidelines that can be refined according to local environmental conditions and to develop site-specific guidelines. The ANZECC/ARMCANZ Guidelines for Fresh and Marine Water Quality (2000) focus on adapting criteria to local conditions as a key part of the ongoing monitoring. The major elements of an effective adaptive management framework combine management, research and monitoring and include: • high quality, baseline information as the basis for planning; • an understanding of receiving environment processes and their response to

management activities; • performance monitoring – to assess whether targets and objectives have been

achieved;


• the capacity to assess the effectiveness of key management activities implemented • review processes to incorporate new information • community and stakeholder commitment and involvement in the long-term

management process.

1.6 The Purpose of this Document

This document is prepared in support of a new Works Approval Application for the upgrade of the Eastern Treatment Plant that is now required in light of the current strategic context, a more up to date and comprehensive understanding of both the receiving environment impacts and the options for addressing them. It includes: • An overview of the scientific studies to date covering the current understanding of

the ecological, health, and aesthetic impacts of the near shore discharge of secondary effluent

• Consideration of the strategic influences on wastewater management for Melbourne and potential water recycling outlook, including the most up to date knowledge on potential local water recycling opportunities from South East Water’s current investigations

• An analysis of the costs, benefits and impacts of the treatment and outfall scenarios investigated, and a proposed preferred upgrade approach

38 Melbourne Water

An extensive program of consultation, environmental monitoring and scientific

investigations has been carried out to inform an assessment of the impacts

associated with the discharge from ETP. This investment in understanding has

underpinned the current ammonia reduction upgrade to the secondary

treatment process, and now forms the basis for the next round of

improvements. This section summarises the studies undertaken and the key

findings that have emerged.

2.1 The Receiving Environment

The secondary-treated effluent in the South East Outfall is discharged at Boags Rocks, near Cape Schanck on the Mornington Peninsula, approximately 70km south of Melbourne. The feature called Boags Rocks is composed of limestone, which is exposed at the shoreline on either side of the Outfall and immediately offshore. Occasionally low limestone reefs protrude above the sea-bed. About 800m offshore, the limestone reef becomes the predominant sea-bed type and these offshore reefs have a considerably higher profile than the reef outcrops in the surf zone. Broad stretches of sandy shoreline, interspersed with reef, lie either side of Boags Rocks. To the immediate north-west the limestone extends as disjunct intertidal reef platform and is exposed at the shoreline in several places along St Andrews Beach. The surf zone adjacent to Boags Rocks is composed of bars and troughs interspersed with small limestone reef outcrops. Sediment movement in the surf zone is very dynamic due to movement of the rip channels and onshore/offshore movement of the bars. The coast adjacent to Boags Rocks is backed by a relatively stable dune system, with occasional blow-outs that overlay sections of the limestone. Boags Rocks and the marine environment surrounding the outfall have been studied intensively over many years. The studies have included monitoring programs, specific investigations as well as observing the effects of operational improvements and the ammonia reduction project at ETP to benefit the marine environment. Now Melbourne

2. Why Upgrade The ETP?


Water believes it is well informed to assess the current discharge arrangement and the likely improvements to the marine environment with the various upgrade scenarios available.

2.2 Overview of Marine Studies History

The studies that have been undertaken include: • A range of pre 1996 studies including; weather and tide studies, intertidal rocky

platform monitoring, and bioaccumulation studies • The CSIRO Effluent Management Study over 1996-99 • A suite of additional studies undertaken in 2005-2006 • The current monitoring program designed by the CSIRO and regularly reviewed

and updated over more than 10 years with records and adaptive management process in place that can identify ecological change over time. The program includes; - Effluent sampling and chemical analysis - Effluent toxicity assessment - Contaminant accumulation studies - Intertidal platform algal surveys and platform mapping - Subtidal video surveys of substrate - Assessments of health risks to recreational use in the area influenced by the

discharge from the Eastern Treatment Plant. • The beach aesthetics inspection program undertaken since 2002. • Tertiary technology trials undertaken in 2008 have provided valuable information

on the performance of a range of treatment trains to meet EPA requirements and to address the aesthetic concerns associated with the discharge at Boags Rocks. The trials and outcomes are discussed further in section 4.

The following sections summarise these studies and the insights gained into the marine environment impacts including public health, marine ecology and aesthetic/amenity aspects that can be attributed to the ETP effluent discharge. Additional discussion can be found in: • Appendix 2 - Summary Report 2009 Aesthetic and Amenity Aspects • Appendix 3 - 2004-2007 Monitoring report (CSIRO et.al.) • Appendix 4 - Hydrodynamic Modelling report 2009 (GHD)

2.3 Studies Prior to 1996

40 Melbourne Water

The following is summarised from Newell et. al. (1999).

2.3.1 Weather and Tides

During 1953-54 radar was used to track floats released offshore from Boags Rocks. There had been a perception that the tides would take the discharge from an outfall back into Port Phillip Bay, but the studies showed the predominant currents flowed to the east. Sokolov and Black (1994) reported that there is a pronounced seasonal variation in wind patterns around the Boags Rocks area. During winter, the predominant wind is from the north-west with a maximum mean wind velocity of 7m/s. In summer, south-west and easterly winds prevail with a maximum mean wind velocity of 6m/s. North-west and south-westerly winds prevail during spring and autumn, respectively. Waves have been monitored at Boags Rocks (August 1971 to April 1972) and at Flinders (November 1990 to February 1991) (Sokolov and Black 1994). The maximum wave height recorded offshore from Boags Rocks was 7.16m and the wave periods varied between 10 and 15 seconds. The median significant wave height recorded at Flinders was 1.3m. The significant wave height exceeded 2m for 10% of the time and remained below 0.7m for 10% of the time. Directional data was not available from either of these stations. Due to the orientation of the shoreline, waves that can directly impinge on Boags Rocks must have a directional origin between 190° and 250°. The important currents at Boags Rocks include nearshore currents, tidal currents, coastal-trapped waves, wind-driven currents and thermohaline currents (Sokolov and Black 1994). Nearshore currents (inside the surf zone) are particularly important in controlling water movement in the area immediately adjacent to the existing outfall. These include longshore currents driven by obliquely incident waves, which vary in strength and direction with variation in wave approach. The other nearshore currents of importance are the rip currents, which operate to discharge water from the surf zone and may reach velocities up to 1m/s. Surface drogue measurements taken offshore from Boags Rocks showed that the surface water movement is significantly influenced by the winds. It can occur in both directions parallel to the shore, though south-easterly currents are dominant giving a net longshore movement in that direction (Sokolov and Black 1994). The surface drogue measurements indicated that the net cross-shore movement of water associated with the turn of the tide could be up to 600m and that the current velocity increased with distance offshore.


2.3.2 Early receiving environment impact monitoring

In trying to assess the impact of the discharge on the marine receiving environment for Boags Rocks a major confounding factor is that monitoring undertaken prior to commissioning of the outfall (Manning 1979) was insufficient to allow statistically robust ‘before and after’ type comparisons to be made. These issues mean that assessing the extent of impact and determining whether it is increasing or decreasing is a difficult objective to meet. Considerable effort has been expended since 1975 in surveying the intertidal rocky platforms along the coast between Point Nepean and Cape Schanck. Manning (1979) undertook surveys at four sites – one at the outfall site itself, two at 700 m (Boags Rocks East) and 5km (Fingals Beach) southeast respectively, and one situated 16km to the northwest (Sorrento). Two surveys were conducted before discharge began and six afterwards, from July 1975, to August 1976. Manning commented that before discharge the four sites displayed differences in algal and mollusc species composition with "considerable differences in the relative density of many common mollusc species". After discharge commenced, the most noticeable effect was a decline in abundance of brown algae, including Neptune’s Necklace (Hormosira banksii), at the outfall site with some attendant changes in other taxa. Manning also reported similar effects at Boags Rocks East. From 1980 to 1994 numerous other surveys were conducted at a total of eleven sites near and distant from the outfall, including some of those of Manning, together with supplementary sites. All were on the accessible rocky platforms. Seven reports were prepared, elaborating, building on, and refining the early findings of Manning. Key observations near the outfall were the loss of Hormosira banksii, an increase in the abundance of turf algae and establishment of the sand consolidating polychaete worm Boccardia probiscidea and associated decline in Capreolia. Quinn and Haynes (1996) reviewed all the published material in a report to Melbourne Water. Their overall conclusion was that rocky platforms do not provide a useful substrate for assessing the extent of biological effects of the outfall even on the basis of comparing the outfall site with supposed "control" sites. However, despite rocky platform monitoring not being able to satisfy strict power statistical requirements of single species analysis, the rocky platforms have still provided the best indication of the extent of biological impacts of all methods tested so far, and hence are monitored as part of the newer biological monitoring program (discussed further in sections 2.5 and 2.6).

42 Melbourne Water

In 1986, the (then) MMBW arranged for samples of wrasse flesh and livers and abalone flesh to be collected from near Boags Rocks and analysed for a suite of 10 organochlorine pesticides. The levels found in the flesh of both species were about two orders of magnitude lower than the levels found in the livers of the wrasse, which themselves were well below EPA Standards for Human Consumption. A more extensive program was conducted in 1991, when samples of limpets, abalone and the periwinkle (Turbo) were collected at Boags Rocks, Boags Rocks East and West and Number Sixteen sites. Samples of the horseshoe leatherjacket were taken at Boags Rocks and Number Sixteen only. All samples were analysed for four organochlorine pesticides (Lindane, Aldrin, DDE and Dieldrin), PCBs and dioxins and furans. All levels were well below EPA Standards, even when the four pesticides were summed under the EPA combination rule. Levels were, however, extremely variable within samples.

2.4 The CSIRO Effluent Management Study – 1996-99

2.4.1 Introduction

In November 1996 Melbourne Water commissioned the CSIRO as principal consultant to conduct a major environmental research project. The project was initiated by Melbourne Water and EPA Victoria to provide an initial knowledge base for future management of the plant discharge. The two-year, $1.3 million multi-disciplinary project became known as the Effluent Management Study (the Study). The Study incorporated research conducted by CSIRO scientists, local universities and environmental consultants as well as investigations undertaken by engineering consultants (Newell et al. 1999). Its framework was developed in consultation with stakeholders representing government agencies, peak environmental groups, surfrider organisations and local community interest groups. An extensive community consultation program was undertaken in conjunction with the study. Consultation involved a high level of interaction with the reference groups mentioned above and regularly updating local government, local Members of Parliament and the general public on the Study’s progress through newsletters, media releases and a touring display. An external review panel was also established with independent academics and engineering experts to provide a peer review of the Study outcomes and recommendations.


The Study was completed in July 1999 when CSIRO published a final report entitled Environmental Impact Assessment and Review of the Effluent Disposal Options for Eastern Treatment Plant (Newell et al. 1999).

2.4.2 Study Program

The Study commenced with a review of published work and past studies conducted by Melbourne Water and external parties since 1974 to enable the existing knowledge about the impact and nature of the effluent to be consolidated. The review identified knowledge gaps, which needed to be explored to better understand the ecology and physical processes influencing the environment of Boags Rocks and nearby waters. Accordingly a program of fieldwork and desktop investigations was devised. The program included research tasks and investigations such as: • Biological monitoring to determine whether the plant discharge is having an effect

on intertidal and subtidal biotic assemblages • Bioaccumulation to measure toxicant content in selected species of seafood • Toxicity assessment to identify harmful effluent components using a suite of

pollution sensitive organisms from a number of trophic levels • Receiving water quality assessment to establish concentrations of selected

toxicants and nutrient levels in receiving waters • Microbiological water quality assessment to assess health risk to swimmers and

surfers • Oceanographic studies to establish dispersion patterns of the current outfall and to

model the performance of an extended outfall • Treatment improvement investigations to determine benefits of upgrading the

existing treatment process to further reduce ammonia concentrations in the plant effluent.

The data obtained from these research and investigation activities significantly increased the understanding of the complex Boags Rocks environment. The research tasks carried out between January 1997 and October 1998 to assess the effects of effluent discharge on the environment are described in more detail below.

2.4.3 Biological Monitoring

A common objective of biological monitoring is to establish the extent of impact from human activity over time and space. Indicator species from one or more ecosystems

44 Melbourne Water

are usually monitored to establish whether continuing activity causes detectable changes in the monitored area. During the course of the Study researchers surveyed the following ecosystems: • Macroalgae of the intertidal rocky platforms • Infauna of the intertidal beach sediments • Epibiota of the subtidal reefs • Infauna of the subtidal soft sediment Macroalgae surveys of intertidal rocky platforms were conducted at seven sites in autumn, winter, spring and summer. Present taxa were identified, their distribution and percentage cover noted. Data from the past intensive surveys was used to assess change at the monitored sites. It was found, consistent with earlier Melbourne Water intertidal monitoring studies, that the rocky platforms at the plant discharge point had lost their original brown algal assemblages. Loss of Hormosira banksii and Durvillea potatorum was particularly apparent. A spionid worm Boccardia proboscidea and opportunistic green algae and a few invertebrates colonise the area at present. The CSIRO indicated that biological observations further away could not be clearly attributed to the plant discharge, due to the high level of natural, seasonal and year-to-year variations. A preliminary investigation of the intertidal beach sediments infauna was also conducted. However this habitat was deemed as not suitable for monitoring due to low abundance of species, making spatial comparison difficult. Infauna of the subtidal soft sediment was investigated initially at two sites – both 640m offshore – one opposite the outfall and another 4.2km to the northwest. Divers undertook a more extensive survey later on, at 12 sites located between 4km northwest and 3km southeast. High abundance of species was noted. Changes in abundance and biomass of infauna were found but it was concluded that sand grain size and organic content of sand were confounding factors in assessing the impact of effluent on local communities. The difficulties in reliably surveying and counting infauna in an energetic marine environment meant that the subsequent monitoring program design was set up with a focus on detecting change in dominant homogenous species using more reliable methods such as macroalgal surveys. Two offshore reef surveys were conducted during the Study. The initial survey was undertaken at five sites. Three sites were located 500m off the outfall and another two, 4km northwest and southeast away from the outfall. Based on the information


obtained, a few months later a more detailed survey of five transects to the southeast of the outfall was conducted to determine the extent of impact. Rich flora and fauna were recorded in both surveys. However statistical assessment of the data indicated that the effluent discharge might affect surveyed epibiota up to 1.1km away from the outfall and to a lesser extent up to 1.4km (work since, including extensive video surveys, has indicated a healthy sub-tidal community offshore1).

2.4.4 Bioaccumulation in Seafood

Tests on biota collected in close vicinity to the outfall (200–500m) were conducted to determine whether concentrations of selected toxicants are within current health guideline limits. Bioaccumulation of toxicants was tested on one commercial and one recreational species using a sample size of 10 of each species. The organisms selected were black-lip abalone (Haliotis rubra) and blue throated wrasse (Notolabrus tetricus). A filter feeder organism, cunjevoi ascidian (Pyura stolonifera), was also included in a suite of tests to assess accumulation of suspended matter from the effluent. Biota tissue samples were analysed for four heavy metals – lead, copper, chromium and nickel, and four organic toxicants – toluene (a hydrocarbon commonly used as a solvent or found in petrol), and the widely used plasticisers diethyl phthalate (DET), di-n-butyl phthalate (DBP) and di-(2-ethylhexyl) phthalate (DEHP). No significant bioaccumulation of the toxicants tested in seafood was reported.

2.4.5 Effluent Toxicity Assessment

Melbourne Water monitors the quality of the plant effluent through regular chemical testing, a common method used by most water authorities. Historically, compliance limits for individual and groups of chemicals, including toxic components, were set for the effluent in the plant EPA licence. However, with advances in the field of toxicology, biological methods are now also used to examine whole effluent toxicity.

1 The CSIRO 2004-2007 monitoring report (see Appendix 3) indicated “Video records show a healthy subtidal community offshore. Ecklonia kelp and associated macroalgal understorey assemblages continue to be the dominant community component. The major biological categories were Ecklonia kelp, red foliose algae and red coralline algae. Further offshore (1.5-3.5 km) in the deeper water, Ecklonia density generally decreases, with red algae becoming the predominant plants, and ascidians (stalked and encrusting) and sponges also becoming more common.” The variations in abundance and reef communities were related to depth and natural differences in seabed and habitat.

46 Melbourne Water

The Study used a series of tests on sensitive species from different levels of the food chain, to assess acute and chronic toxicity of the plant effluent. Strict test protocols were established to ensure quality control of laboratory procedures. The effluent was collected in June, September and November 1997 to ensure seasonal changes in effluent quality were captured. Acute tests, measuring lethal and sublethal effects, were carried out on bacteria Vibrio fischeri, fish larvae of Australian bass (Maquaria novemaculata), and estuarine perch (Maquaria colonarum). Chronic tests, measuring prolonged toxic effects, were performed on microalga Nitzschia closterium, macroalga Hormosira banksii, and larvae of the doughboy scallop (Chlamys asperrima). All test organisms were exposed to at least five concentrations of effluent, including its full strength. Obtained results were presented as lethal concentration affecting 50% of tested organisms (LC50), Lowest Observable Effect Concentration (LOEC) and No Observable Effect Concentration (NOEC). The effluent was found to be non-toxic to bacteria, 1-3 day old fish larvae, and macroalgae fertilisation. It was mildly toxic to 4-5 week old fish, and inhibitive to microalgae and macroalgae growth. The most sensitive species from these original round of tests (with high ammonia effluent of the time) was scallop larva with two tests returning NOEC value of 0.5% (i.e. 200 times dilution). Internationally recognised risk assessment methods were applied to derive required effluent dilution or exposure reduction to protect 95% of the species. Based on the results of the experiments it was concluded that 300 times dilution of the then applicable effluent quality would result in no significant toxic effect. Toxicity Identification Evaluation (TIE) tests were also carried out on microalgae to identify a substance causing toxicity of the effluent. The results pointed to ammonia as a causative agent of the observed toxicity. Ammonia was identified as a key toxicant which has reduced the prevalence of the Hormisira Banksii on the rocky platforms surrounding Boags Rocks. To address these impacts the secondary treatment process was upgraded to allow for the ammonia to be reduced in the final effluent. The ammonia reduction process has been operational since September 2007 and data indicates a greater than 85% reduction in average ammonia in the final effluent compared with historical levels.


2.4.6 Receiving Water Quality

The receiving water quality task complemented bioaccumulation and effluent toxicity testing carried out during the course of the Study. The objectives of this task were to: • determine whether concentrations of selected toxicants in seawater samples were

within the EPA Recommended Water Quality Criteria, and • determine distribution of ammonium, oxidised nitrogen, phosphate, silicate,

salinity, temperature, dissolved oxygen and chlorophyll-a in receiving water. Seawater samples were collected at six sites between 200 and 500m radius from the discharge point to establish the concentration of selected toxicants. The samples were analysed for the same toxicants measured in the bioaccumulation task with the exception of dioxins and furans. The last two were excluded, because levels found in abalone and fish were very low and it was unlikely the compounds would be detectable in water. Ammonium (NH4

+) concentration was also measured in all samples and levels of the toxic component – undissociated ammonia (NH3) – was calculated using known salinity and pH. All heavy metals were found to be well below the EPA Victoria Recommended Water Quality Criteria levels. Two of the organic toxicants were undetectable. Only one, phthalate ester derivate (DEHP) was found above guideline levels at two sites, being undetectable at others. The concentrations of undissociated ammonia were above the recommended limits. Four underway water quality sampling cruises were undertaken in 1997–1998 to establish concentrations of nutrients. On these occasions ammonium, oxidised nitrogen, phosphate, silicate, salinity, temperature, dissolved oxygen, and chlorophyll-a were continuously measured at 5km distance west and east from the outfall and 5km offshore. A few vertical profiles throughout the water column were also taken. Collected measurements provided calibration data for a hydrodynamic model. It was concluded that dissolved oxygen was within the EPA guidelines. Levels of chlorophyll-a were measured at background levels for southern Australian coastal waters, but higher than background concentrations of dissolved inorganic nitrogen were also recorded.

2.4.7 Health Risk Assessment

During the course of the Study a desk-top microbiological health risk assessment of the waters adjacent to the Outfall was carried out by the Department of Epidemiology

48 Melbourne Water

and Preventive Medicine at Monash University. This work reviewed a range of epidemiological studies conducted elsewhere which have attempted to assess the risk of disease associated with swimming in various water qualities, with most studies concentrated on gastroenteritis. Indicator organisms E.coli, enterococci or faecal streptococci have been correlated with an increase in disease risk, and accordingly most regulatory frameworks for water bodies where human contact occurs use these for assessing risk. As part of the EPA discharge licence requirements for Eastern Treatment Plant, Melbourne Water carried out routine sampling for E.coli at beaches either side of the discharge point every six days. The nature of the relationship between E.coli levels and the risk to swimmers is not a simple and direct one, as E.coli only indicates the likely presence of other potentially harmful organisms. Data from the monitoring indicated that the E.coli. levels are significantly below the limits set by the EPA. This data supported a conclusion that it was unlikely that swimmers or surfers at Gunnamatta Beach would be at increased risk of illness due to faecal microorganisms in the treated effluent being discharged at Boags Rocks, compared to swimmers or surfers at other ocean beaches. There are some limitations associated with the use of indicator organisms to derive such assessments and this has led to later work with alternative approaches. A second Monash University study followed publication of World Health Organisation Draft Guidelines for Safe Recreational-Water Environments: Volume 1: Coastal and Fresh Waters. Chapter 4: Faecal Pollution and Water Quality in October 1998. The WHO also published in early 1999 the report Health Based Monitoring of Recreational Waters: The Feasibility of a New Approach (The Annapolis Protocol), which was the outcome of an expert group meeting held in November 1998 at Annapolis, USA. This latter document proposed a classification scheme based on both indicator bacteria levels and sanitary assessment of human health, and this type of approach (subsequently adopted in the NHMRC published “Guidelines for Managing Risks in Recreational Water”) indicated the recreational waters around Boags Rocks and Gunnamatta Beach consistently achieve a ‘Good’ to ‘Very Good’ risk classification.

2.5 Studies from 2001 Onwards

CSIRO was engaged to design a long-term monitoring program for the ETP receiving environment. The pilot phase from 2001 to 2003 provided further insight and understanding on the nature and extent of the impact caused by the effluent


discharge at Boags Rocks. It also established baseline monitoring that provided a means for measuring improvements in the environment from treatment upgrades such as the move to ammonia reduction, and potential future augmentations of the Plant and Outfall. Additionally, the pilot phase allowed exploration of new monitoring techniques, which form the basis for future long-term monitoring. The 2004 – 2007 monitoring program was approved by EPA Victoria in November 2004, with components including: • effluent and receiving waters monitoring; • biological monitoring; • contaminant accumulation; and • aesthetics and recreational impact. Effluent monitoring and toxicity testing assess the quality of the effluent being discharged, five components deal directly with measuring conditions in the receiving environment, and two measure aesthetic impacts and risk to public health.

2.5.1 Effluent sampling and chemical analysis

Managed by Melbourne Water - parameters and frequency of sampling as prescribed in discharge licence.

2.5.2 Recreational Water Quality Sampling

Compliance with the State Environment Protection Policy (SEPP) ‘Waters of Victoria’ recreational water quality objectives for E.Coli and enterococci is measured through weekly sampling at six shoreline monitoring sites around Boags Rocks. Melbourne Water set up a voluntary monitoring program in 2000 which monitors enterococci levels at 18 sites in the swim and surf zones and a reference site two kilometres offshore.

2.5.3 Aesthetics – beach inspections

Managed by Melbourne Water - Beach inspections at low tide; check general condition of water, noting colour, odour and foam on the Beach Inspection Report Log Sheet. Redesign of the log sheet improved the reliability of the data, and has assisted in assessment of the causative agents for foam, odour and visibility. More detailed statistical analyses informed the understanding of the cause-and-effect associations which lead to odour, foam and plume visibility at Boags Rocks.

50 Melbourne Water

2.5.4 Effluent Toxicity Assessment

Undertaken by CSIRO - Direct toxicity assessment of effluent is carried out using marine organisms, including quarterly scallop (MimaChlamys asperrima) larvae development tests and other toxicity investigations to assess the impact of reduced ammonia and salinity on a range of test species. Micropollutants of natural and anthropogenic origin are present in sewage and to a much lesser extent in treated effluents. These include chemical stressors, such as ammonia, heavy metals, biocides and other organic compounds. Some pollutants have potential health and environment impacts. Human health impacts of micropollutants in secondary treated effluent discharged to open coastal marine environments such as Bass Strait are considered to be negligible as: • Effluent concentrations are very low – typically part-per-billion to part-per-trillion, • There are few significant pathways for human exposure to effluent constituents

either by direct ingestion or indirectly via food consumption, and • The receiving environment is highly dispersive and dilutions are high Discharges from wastewater treatment plants have the potential to cause some environmental impacts to surrounding aquatic ecosystems. It is not possible to analyse for all the micro-pollutants potentially present in effluent and so predict environmental impacts. Current practice is to undertake Direct Toxicity Assessment (DTA) or Whole Effluent Toxicity (WET) testing as a means of assessing and managing potential treated effluent impact on marine and freshwater environments. DTA provides a direct measure of toxicity and bioavailability of mixtures and obviates the need to analyse for numerous toxicants. Toxicity testing results are expressed as IC50/EC50 %, LOEC and NOEC. IC50 is the percentage concentration of effluent at which the test organism shows inhibition at 50% of the control response. EC50 %, is the percentage concentration of effluent at which the test organism shows effects at 50% of the control response. For example, in the case of the microalga Nitzschia, where growth is measured over 72 hours (3 to 4 doublings of cell numbers in seawater controls), the EC50 is that concentration of effluent in which only half this growth rate is achieved. The LOEC is the Lowest Observable Effect Concentration where statistical testing of the results indicates the smallest significant difference from the controls. NOEC is the No Observable Effect Concentration where no significant toxic effects are detectable and so can be used to calculate “safe” dilution of the effluent.


2.5.5 Intertidal platform algal surveys

Undertaken by Consulting Environment Engineers (CEE) P/L, with analysis by University of Melbourne Australian Centre for Environmetrics - Intertidal rock platforms are considered to be the prominent habitat impacted by the discharge. Surveys are being undertaken to assess any change in occurrence of common macroalgae at sites including Boags Rocks, Boags Rocks East and Fingals Beach. Results are compared with established baselines. Quadrat presence/absence surveys have been undertaken on intertidal rock platforms (9 sites) to assess change in occurrence of common macroalgae (Hormosira, Ulva, Cladophora, and Corallina) and Boccardia. Surveys provide a coarse resolution test for assessing change in the impact (temporal and spatial) from the effluent on indicator species in the receiving environment. The biological condition of the shoreline area in the vicinity of the discharge has been described, covering nutrient and toxicant effects and summarising changes to the local flora/fauna over the past 30 years. The current biological monitoring program of the intertidal platforms was reviewed by the Australian Centre for Environmetrics and adjusted to improve its ability to provide a basis for measuring changes in flora and fauna as a result of the proposed upgrades.

2.5.6 Metals accumulation in biota and sediments

Undertaken by PIRVic - Composite samples of the local mussel Brachiodontes rostratus obtained from Boags Rocks and a reference site, for analysis of metals in December 2005. Monitoring using mussels is being conducted to ensure that metals, which may pose a risk to human health via seafood, are not accumulating in the environment where the effluent is discharged (the monitored species is not actually a human seafood, but is used as a surrogate).

2.5.7 Underwater video surveys of subtidal reefs

Undertaken by CEE P/L - Qualitative evidence is required to ensure that the discharge has had no significant impact on the subtidal reefs offshore from Boags Rocks. Diver-assisted underwater video footage along sections of the subtidal reef (14-18 m depth), which are taken every three years, cover a 7 km area either side of the discharge point. Remotely controlled underwater video footage of the substrate along transects perpendicular to the shore was also undertaken. The program allows for more frequent footage to be taken if significant change is occurring. The video

52 Melbourne Water

surveys undertaken in March 2006 indicate no significant change since the last surveys in 2003 and previously in 2002. The next survey is planned for early 2010.

2.5.8 Quantitative Microbial Risk Assessment

The Australian “Guidelines for Managing Risks in Recreational Water” (NHMRC 2008) enable a beach rating to be obtained based on the long term monitoring of bacterial indicator organisms (enterococci) and an assessment of the standard of treatment and effectiveness of the outfall. Based on these guidelines the recreational waters around Boags Rocks and Gunnamatta Beach consistently achieve a ‘Good’ to ‘Very Good’ risk classification. There is potential for effluent disinfection methods e.g. combined chlorine, to alter the relationship between the bacterial indicators and the pathogenic organisms, and yield an incomplete picture via this risk classification approach. Indicators such as E. coli and enterococci are more susceptible to combined chlorine disinfection than some pathogens, so a low indicator organism count could occur along with elevated numbers of certain pathogens such as enteric viruses and cryptosporidium. An approach more recently emerging for the assessment of complex risks is Quantitative Risk Assessment. This type of methodology is now beginning to be applied more widely, including for the assessment and control of risks in the treatment and supply of drinking water and recycled water. In this case, a Quantitative Microbial Risk Assessment can be developed to gain further insight into the risks associated with the recreational use of the waters in the vicinity of the outfall discharge point. The QMRA approach uses a wider range of pathogenic micro-organism species, and considers their individual characteristics, and thus provides an additional layer of information than using indicator organisms only. The QMRA methodology is a general risk assessment methodology adapted for risk exposures to recreational bathers and includes the following steps: • Problem formulation - Risk of illness • Hazard identification - Exposure to pathogens in water • Exposure assessment - How much water ingested • Dose-response assessment - Numbers of pathogens and dose response • Risk characterization - Compare with NHMRC risk categories


The NHMRC recreational guidelines provide a bathing risk classification based on long term monitoring while QMRA provides a means of calculating an event based risk assessment based on transient conditions such as peak flows. The two methods are consistent and complementary. Data has been gathered on both indicator organisms and pathogens (bacteria, viruses, etc) measured in ETP treated effluent and from the literature. Using effluent dilutions in the shoreline and surf zone waters from the CSIRO hydrodynamic model, microbial populations in the seawater can be calculated. The infectivity of organisms, rate of organism die off in seawater and volume ingested by recreational users can be obtained from published literature. Risk of infection can then be calculated and compared with NHMRC beach classification guidelines.

2.5.9 Hydrodynamic Modelling

Consultant GHD developed a new hydrodynamic model in 2006 to assess the effluent dilution patterns for future discharge scenarios. The new modelling built on the hydrodynamic modelling and data collection undertaken by CSIRO in 1997-1998, and on the shoreline sampling (nutrient and salinity data) undertaken by Melbourne Water. The GHD modelling provided higher resolution and improved simulation of effluent dilution along the shoreline. Additional shoreline sampling of nutrient levels and salinity levels was initiated during March 2006 to correlate with the numerical modelling. An updated summary of this hydrodynamic modelling work is attached as Appendix 4.

2.5.10 Ongoing Monitoring Program

An ongoing monitoring program has been proposed in Sections 4 and 5 of Appendix 3. The detail and frequency of this program is to be agreed with EPA Victoria prior to formal commencement of the next phase of the monitoring program. In the interim the starred items (*) listed below have been commenced in whole or in part, and in some cases reported. The activities proposed include: • Routine Direct Toxicity Assessment screening using sensitive chronic toxicity test *

- Chronic toxicity using the scallop larvae development test - Trigger if toxicity is > 10TU or not attributed to ammonia, then initiate further

testing and TIE - Periodically carry out full suite of ecotox tests and recalculate safe dilution

• Effluent Monitoring *

54 Melbourne Water

- Ongoing monitoring of effluent licence parameters • Beach Water Sampling

- Ongoing testing of shoreline and surfzone for health related and selected physical parameters

• Nearshore Nutrient Analysis - Sampling to assess platform exposure to nutrients

• Contaminant Accumulation Monitoring in Mussels - Testing for metals and selected toxicants

• Intertidal Platform Algal Surveys * - Quadrat based surveys on intertidal rock platforms to assess change in

occurrence of selected indicator species. • Intertidal Platform Mapping

- Field based mapping methods prepare habitat maps in selected areas on platforms around Boags Rocks

• Subtidal Reef Surveys • Platform Inspections • Routine beach inspections for aesthetic parameters * • Recreational Bathing Water Health Risk assessment *

2.5.11 Tertiary Technology Trials

The tertiary technology trials have considered the impact that the various treatment trains are likely to have on key environmental parameters, including effluent toxicity, ability to reduce contaminants, the ability to limit ammonia peaks and organic solids. A greater understanding of the pathogen reduction capability and likely impact that this will have on recreational water quality at Boags Rocks has been developed. This is discussed further in Section 4.

2.6 What the Studies Have Told Us

The extensive program of investigations has yielded a clearer understanding of the interactions between ETP operations and the marine environment. This consolidated picture is summarised in Sections 2.6.1 to 2.6.13, and additional detail is provided in Appendices 2, 3 and 4.


2.6.1 Effluent Dispersion - Hydrodynamic Modelling

The original CSIRO modelling work undertaken between 1997 and 1999 at a resolution of 250m by 250m indicates the following surface dilution levels of effluent for the present outfall and a notional 2 km extension.

Existing 2 km extension

Cell where dilution assessed (250 m by 250 m)

Average dilution

5th percentile

Average dilution

5th percentile

centreline of outfall, at shore 23 14 253 102

centreline of outfall, 1km offshore 149 47 153 72



2km southeast, at shore 67 31 276 112

2km southeast, 1km offshore 216 71 252 110

5km southeast, 1km offshore 218 81 384 141

5km southeast, 3 km offshore 1720 388 1067 250

2km northwest, at shore 105 35 303 113

2km northwest, 1km offshore 205 62 266 101

5km northwest, 1km offshore 434 113 549 175

5km northwest, 3 km offshore 1006 224 632 181 Table 2-1: Predicted Dilution Levels from CSIRO Modelling

Further examination of the hydrodynamic conditions near the current outfall, in particular to use a model with finer resolution (90m) in this area were subsequently undertaken by GHD. This work used the same effluent flow profile as the CSIRO work, with average flows over the 12 month period modelled approximately 11% greater than current average discharge. The dilution results predicted at the same points as for the CSIRO work are shown in Table 2-2 below.

Site Average dilution 5th percentile

centreline of outfall, at shore 8 5

centreline of outfall, 1km offshore 106 81



56 Melbourne Water


2km southeast, at shore 101 63

2km southeast, 1km offshore 269 180

5km southeast, 1km offshore 477 209

5km southeast, 3 km offshore 3121 1159

2km northwest, at shore 81 49

2km northwest, 1km offshore 183 131

5km northwest, 1km offshore 267 154

5km northwest, 3 km offshore 2422 1443 Table 2-2: Summary of Effluent Dilution Predicted Under the Effect of the Tides, Low Frequency Sea Level Motion and Winds at the CSIRO monitoring locations (12-month simulation period).

Predicted dilutions at more closely spaced points along the shoreline for up to 1 km in either direction from the discharge point are shown in the Table below.


1000 metres west 57 37





20 metres west 8 5

20 metres east 8 5

160 metres east 13 8




1000 metres east 61 39 Table 2-3: Summary of Effluent Dilution Predicted Under the Combined Effect of Tides, Low Frequency Sea Level Motions and Winds at Key Sites (12-month simulation period)

Average dilution rates in excess of 20:1 were predicted at greater than 250m from the outfall, and in excess of 50:1 at greater than 750m from the outfall. Near field dilution modelling using USEPA’s VP Plumes model with varying discharge rates from 260-475 ML/day yielded initial dilutions of around 3:1 within 5m of the current discharge point.


Mixing zone sizes required for varying dilutions from the current outfall are summarised below.

Average dilution East West Offshore

10:1 75m 75m 100m

20:1 250m 200m 200m

50:1 800m 800m 500m

100:1 2km 2.5km 750m Table 2-4: Mixing zone sizes for varying dilution from nearshore outfall

The output from the higher resolution modelling approach is also summarised graphically below in Figure 2-1.

Figure 2-1: Mean Dilution Contours

2.6.2 Biological Interactions

In addition to the significant volume of freshwater, the effluent being discharged at Boags Rocks contains small concentrations of nutrients, toxicants, pathogens, sediment and other dissolved matter. The concentration of each contaminant varies depending on the level of treatment, which in turn is dependent on the characteristics of the influent. The nutrients are likely to be taken up by both macroalgae and phytoplankton, while other animals within the water column (e.g. zooplankton and fish) will feed directly on

58 Melbourne Water

the particulate matter, which may include toxicants such as metals. These will also be taken up by filter feeding animals such as mussels. Subsequently the phytoplankton and smaller animals will be consumed by larger animals thus transferring the contaminants. This can result in bioaccumulation (when organisms accumulate chemicals) or biomagnification (when chemicals are accumulated and then passed up the food chain to concentrate in higher consumers). Data on plankton offshore from Boags Rocks are limited to measures of chlorophyll-a concentrations. Results from the chlorophyll fluorescence monitoring showed that the effluent discharge did not result in significant phytoplankton biomass (algal blooms) near Boags Rocks. Measurements of nutrients in the nearshore waters suggest that nutrient concentrations prior to commissioning of the Outfall did not vary significantly along the coast. However, as the volume of discharge increased, the exposure to increased concentrations of nutrients by intertidal communities increased in proportion to the effluent. Observations at reefs near Boags Rocks by Parry and Restall (2006) suggested that algal productivity may be higher near the Outfall. Observations on artificial plates in the field found that algae grew faster at Boags Rocks than at Cheviot Beach and Cape Schanck, possibly in response to elevated nutrients. At Boags Rocks, the effects of toxicants and nutrients on community structure are now difficult to detect because most of this reef is covered by the exotic polychaete worm Boccardia probosidea. Colonization by the worm has resulted in a layer of muddy sand, 1 to 20 cm thick on the substrate, making it unsuitable for many reef-dwelling species. It is therefore difficult to determine whether the absence or increased abundance of particular algae near the Outfall is the result of the direct effects of the effluent or the indirect effects of the habitat change induced by Boccardia (in turn induced by the secondary effluent suspended solids). Certainly, biological communities have altered at Boags Rocks and neither Hormosira nor Durvillaea now occur there. It seems likely that Boccardia itself thrives only near the Outfall because of the elevated levels of organic particulates from the current ETP discharge (the suspended solids in the current secondary effluent). Beyond the immediate vicinity of the Outfall all the evidence suggests that the reduced ammonia effluent should be sufficiently diluted to eliminate toxic effects. One recent hypothesis to explain the main biological changes at all shoreline reefs other than at Boags Rocks is that biological differences between reefs may be the


result of nutrients affecting the outcome of competitive interactions between species of algae and between algae and grazers. The suggestion is that increased nutrients increase the growth rate of turfing algae (especially Capreolia and Corallina) making them more likely to out-compete limpets (especially Cellana tramoserica) for space. This results in less bare space for recruitment of Hormosira sporelings, and extensive algal turfs up to 3-4 cm high may crowd Hormosira plants, and prevent them from regenerating from their holdfasts. If Hormosira growing in a dense turf loses most of its photosynthetic tissue when fronds are torn off during storms, it may have insufficient reserves to rebuild them using only energy derived from a very small, shaded holdfast. The higher nutrient enrichment at Boags Rocks East is also consistent with turf-like Corallina and Capreolia being more dominant on the lower littoral on this reef than on the less enriched Fingals Beach. On Boags Rocks East there is no Hormosira and bare spaces in the lower littoral are restricted to small patches where limpets occur at high numbers, while at Fingals Beach there were observations of larger bare areas and “remnant” Hormosira populations. In both the larger bare areas and in smaller patches at Boags Rocks East and Fingals Beach, limpet biomasses were consistently the highest. On the reefs at Boags Rocks East and Fingals Beach any “spaces” without high limpet densities could be colonised by algae. These and other measurements suggest that turf-algal production is higher on moderately enriched reefs, and competitive balance between turf-like algae and limpets is tilted more in favour of turfs as the nutrient load increases. However, above an (unmeasured) threshold nutrient concentration, nutrients may exceed the requirements of even those algae that are favoured by high nutrient conditions, so that increases in nutrients above this threshold may cause only minimal changes in algal communities. The subtidal area, assessed by video transects, shows a healthy subtidal community offshore. Ecklonia kelp and associated macroalgal understorey assemblages are the dominant community component. The major biological categories were Ecklonia kelp, red foliose algae and red coralline algae. Further offshore (1.5-3.5 km) in the deeper water, Ecklonia density generally decreases, with red algae becoming the predominant plants, and ascidians (stalked and encrusting) and sponges also becoming more common. The variations in abundance and reef communities appear to be related to depth and natural differences in seabed habitat.

60 Melbourne Water

2.6.3 Effluent Toxicity

Whole Effluent Toxicity Testing measures the combined toxicity of the treated effluent on selected representative species, rather than trying to analyse individual toxicants. This provides a check that chemicals which are not routinely measured in the effluent and which are not removed from the effluent stream pose no increased risk to the environment. Previous whole effluent toxicity testing work identified ammonia as the major toxicant in the treated ETP effluent. Additional studies with ETP effluent have confirmed a decrease in effluent toxicity with improved nitrification/denitrification treatment processes to reduce ammonia concentrations in the effluent. Reduced salinity, caused by the impact of freshwater effluent into a saline environment, was also investigated. Tolerance of each test to low salinities was investigated to interpret whether there were any synergistic effects of effluent ammonia and low salinity in each of the effluent ammonia scenarios tested. While reduced salinity did contribute to effluent toxicity, it did not exacerbate the toxic effect of ammonia, i.e. synergistic interaction was not considered significant. Amphipod survival, bacterial bioluminescence and microalgal growth tolerated salinities as low as 18 ‰ (part per thousand, seawater is approximately 35 part per thousand). Fish imbalance was unaffected at salinities greater than 25 ‰, while macroalgal germination and cell division were satisfactory at >27 ‰ salinity. Less tolerant was sea urchin larval development, which was unaffected only at salinities above 31 ‰. Scallop larval development was the most sensitive test to reduced salinity, with no inhibition at 34 ‰ and above. 34 ‰ corresponds to around 1:20 dilution. Toxicity was generally due to ammonia or low salinity. There was no evidence of more than additive effects of ammonia and low salinity to any of the test species. The exception was the acute amphipod survival test, where low salinity increased the toxicity of ammonia. H. Banksii (early life stages) was found to be the most sensitive species to ammonia, but is relatively unaffected by freshwater, only showing effects at less than 4:1 seawater:freshwater dilution. For ammonia concentrations less than 5 mg/L, the safe effluent dilution by seawater is 20:1 (derived as per ANZECC/ARMCANZ guidelines). Ammonia accounted for all of the toxicity to scallop larvae in eight of the ten salinity adjusted ETP effluent samples collected in 2005-07. Scallop larvae was the most


sensitive species to fresh water with effects at <20:1 seawater:freshwater dilution levels. The impact of the Ammonia Reduction Project is evident through reduced effluent toxicity as measured in August 2008. The most recent round of testing recorded the lowest concentration of ammonia in the effluent and the lowest effluent toxicity (to scallops) since March 2005. The toxicity of the effluent to scallops has been accounted for solely by ammonia on twelve of the nineteen samplings undertaken since March 2005. Based on an ammonia concentration of 2.4 mg/L, around half of the observed toxicity of the most recent test could be attributable to ammonia, with approximately 42% of the residual toxicity probably due to other components in the effluent. Effluent samples from the tertiary technology trials have also been analysed by CSIRO. In summary, the testing indicated that advanced tertiary (Ozone-Biological Media Filtered) treated water generally demonstrated lower toxicity for the test species as compared to the other effluents, particularly for key indicators for the discharge such as macroalgae. The ability of the advanced tertiary to further reduce ammonia to very low levels, and offer a significant barrier to other potential lower order toxicants is discussed further in section 4. The derivation from the toxicity testing program of a safe effluent dilution of 20:1 based on ANZECC guidelines is considered a conservative approach.

2.6.4 Metals Accumulation Monitoring

There are three routes by which organisms can be exposed to and accumulate toxicants such as metals – direct accumulation from the water column, accumulation via sediment pore waters or ingested sediments, or food chain accumulation. It is impractical to monitor all possible toxicants due to the number of potential candidate analytes. The recent work has focussed on metals in local mussels (Brachiodontes rostratus), and Boccardia proboscidea to build up a time series database that will assist in trend detection and allow comparison of concentrations with relevant standards, between sites, and with previous surveys. Previous testing of fish, abalone and molluscs for selected toxicants in 1986, 1991 and 1997 indicated that seafood collected in the area adjacent the discharge point was unlikely to pose a risk to public health based on the contaminants considered and analytical techniques applying at the time. However it is prudent to maintain a

62 Melbourne Water

monitoring program to give assurance that there is no change to the risk and emerging contaminants are considered. The resident mussels Brachiodontes rostratus are not considered as a food source for human consumption; however contaminant levels can be compared with available food standards as an indication of the contaminant level. If concentrations were found to be at a level of risk for humans, and or had increased significantly based on previous sampling, a more detailed bio-accumulation study would be undertaken. Brachiodontes rostratus are suitable species for assessment of contaminant accumulation, as mussels use their paired gills to sift particles from the surrounding water. The nutritious elements are used for growth, and those toxicants unable to be excreted are retained in body tissue, which makes them a suitable indicator for accumulation of toxicants. Similarly the tube worm Boccardia proboscidea which is also resident on the platform at Boags Rocks, may retain contaminants within the sediments bound by the tubes it forms on the platform. In September 2001, composite samples of Brachiodontes rostratus were collected from the platform at Boags Rocks and analysed (Fabris 2001). Results indicated that toxicants were well below guideline limits. However when compared to results for another species of mussels (Mytilus edulis) collected from Port Phillip Bay, it appeared that concentrations of copper and nickel were higher than expected. However, given the lack of reference data for Brachiodontes rostratus, this assessment was only speculative, hence the need to obtain results from reference sites. The average metal concentrations in Brachiodontes rostratus from Boags Rocks in the December 2005 sampling indicates that there does not appear to have been any appreciable accumulation of these metals analysed in Brachiodontes rostratus at Boags Rocks. The 2005 sampling included collection of Brachiodontes rostratus from a reference site, St Johns Wood, some 12km away from Boags Rocks, and which was more likely to be indicative of background conditions. Comparison between the reference site and Boags Rocks, supported the suggestion that copper may be accumulating in mussels at Boags Rocks. However the results for nickel were similar between Boags Rocks and the reference site, which did not support the suggestion that nickel was accumulating in mussels. An additional component of the 2005 sampling was the collection at Boags Rocks of sediment samples containing the polychaete worm Boccardia proboscidea. The ANZECC/ARMCANZ, (2000) have set sediment quality guidelines and use the ISQG


(interim sediment quality guidelines) low value as the threshold level that triggers the requirement for further monitoring (ANZECC/ARMCANZ, 2000). The concentrations of all metals in the Boags Rocks sediments were well below the sediment quality guidelines. This is consistent with the suggestion that low concentrations are to be expected because of the dynamic nature of the region; the sediments are highly mobile and are unlikely to retain toxicants in sufficient concentrations.

2.6.5 Intertidal Platform Algal Surveys

Figure 2-2 below indicates the location of intertidal rocky platform monitoring sites along the coastline. There are no intertidal rocky platforms between Number Sixteen and Boags Rocks which provide suitable habitat for H. Banksii. There are no intertidal rocky platforms between Boags Rocks and Fingals which provide suitable habitat for H Banksii.. There are some very small sub-tidal reef areas at 1, 2.8, 3 and 3.5km between Boags and Fingals, however these are unlikely to provide habitat for Durvilleae because of their small size and the degree of scouring that occurs.

Figure 2-2: Monitoring locations

64 Melbourne Water

Figure 2-3: Image of Area to NW of Boags Rocks with Rocky Platform Areas Highlighted

No. Sixteen

Boags


Figure 2-4: Image of Area to SE of Boags Rocks with Rocky Platform Areas Highlighted

To provide a means for detecting large scale change in macroalgal (seaweed) cover on platforms in close proximity to the Outfall, a monitoring technique measuring the presence or absence of selected indicator species was developed. The survey design included measurement in defined 20 m x 20 m areas on selected platforms, the presence or absence in 50 haphazardly placed quadrats (0.5 x 0.5 m) of: • Ulva spp., • Corallina officinalis, • ‘Red algal turfs’ (included Capreolia, Ceramium and other filamentous red algae), • Cladophora, • Hormosira banksii, and • Boccardia proboscidea (tube worm)

A program of monitoring select indicator species in intertidal algal communities, including quadrat presence/absence surveys, has been undertaken since 2001 at the following sites: (i) Boags Rocks: Boags A, Boags B and Boags East (ii) Fingals Beach: Fingals A, Fingals B and Fingals VB (iii) Number 16: No16a, No16b and No16c

Boags

Fingals

66 Melbourne Water

The characteristics of indicator species abundance and mix at the individual monitoring sites was relatively consistent over the period 2001 to 2007, with no obvious trends over the period of monitoring. However, there were substantial differences in the distributions of indicator species at the three monitoring locations which indicates differential impact of the effluent discharge at Boags Rocks and Fingals Beach compared to the unaffected reference sites at Number Sixteen. The general conclusion was that conditions generally remained relatively constant at the monitoring sites over the six years of monitoring to 2007. However the January 2009 survey, which detected H. Banksii. at Fingals Beach, appears to be showing a trend of increasing abundance that may correlate with the reduction in ammonia and nitrogen loads in the effluent discharge, particularly since the implementation of treatment changes to reduce ammonia since late 2007.

Figure 2-5: Intertidal Rocky Platform at Fingals in May 2006


Figure 2-6: Intertidal Rocky Platform at Fingals in 2009 showing recolonisation by H. Banksii.

2.6.6 Aesthetics

The aesthetic impacts at Boags Rocks include plume visibility, litter, foam, oil and grease (fat balls) and odour. These issues are discussed in more detail in Appendix 2. Beach observation data from a systematic daily inspection program, designed by CSIRO, covering the March 2005 to 2009 period is summarised in the following sections. By standardising the beach inspection logsheets and data collection, CSIRO has allowed beach inspection observations to be quantified more effectively and has limited bias introduced through the use of multiple individuals making subjective observations relating to the level of aesthetic impact from foam and plume visibility by a numerical score. Other impacts such as litter are more easily counted, with the tallies being used to form a discrete distribution with different tally ranges having a corresponding numerical score. The observation points used by those undertaking the beach inspections are shown in Figure 2-7 below.

68 Melbourne Water

There are other influences on the perceptions of the aesthetic impacts including environmental factors such as cloud cover, wind, tide/current and the wave-climate.

Boags Rocks

First car park

Gate

N

3 (500m from Outfall)

1 (Car Park)

4 (Edge of beach)

5 (500m from Outfall)

2 (Bottom of hill)

Observationpoints

X (Top of path over hill)

Winddirection

Figure 2-7: Location of Beach Observation Points

Where trends are charted in Figure 2-10, Figure 2-11, Figure 2-15, and Figure 2-17, the results have been averaged on a monthly basis and include 2 standard error bars to show the range of observations. The impacts and contributing factors are addressed in turn below.

2.6.7 Plume Visibility

The treated effluent discharge at Boags Rocks results in a visible plume in the receiving marine environment. Plume visibility is believed to be essentially the result of a combination of the current secondary effluent characteristics including suspended solids concentration, dissolved or ‘true’ colour, foam and surfactants. Of these factors, true colour is the most significant contributor to overall plume visibility. It has also been found to impact on customer acceptance of recycled water products. Colour is measured as true colour or apparent colour. True colour is the dissolved colour in the water and cannot be removed by normal media or membrane filtration processes. Apparent colour incorporates the perception of both particles (suspended solids and turbidity, which can be removed through filtration) and the true (dissolved) colour component.


The colour and nature of the seabed will also affect the ability to observe the difference between the ocean and the outfall plume. The local seabed surrounding the Boags Rocks outfall is varied with sand, vegetation and rocky reefs. These are interspersed in the area and this may influence observations. At times of very low mixing the tendency of the lower salinity effluent to ‘float’ on the surface may also make a small contribution to changed surface conditions and perception of a plume. Weather conditions may also influence the perceptions of plume visibility. On a clear sunny day when the ocean is calm it is more likely that an observer will be able to detect a coloured plume against a light sandy background for instance.

Figure 2-8: Aerial view of the discharge showing visible plume

The dissolved colour contributes approximately 80% of the median total or “apparent” colour measured in the current treated effluent (the balance is contributed by the effect of suspended solids). The photo in Figure 2-9 below is an example of low solids effluent still leading to a visible plume under very low mixing conditions – illustrating the key role of dissolved colour.

70 Melbourne Water

Figure 2-9: Onshore view of the discharge showing visible plume due to dissolved colour

Figure 2-10 below shows the summarised results from the two observation points closest to the discharge location, and charts the monthly average observations (where 1=not visible -no difference to background, 2=slight discolouration compared to background, and 3=distinct colour change between plume & background).


Average Plume for Boags Rock (2005-2009)

1.00

1.20

1.40

1.60

1.80

2.00

2.20

2.40

2.60

2.80

Feb

2005

May

200

5

Aug

2005

Nov

200

5

Mar

200

6

Jun

2006

Sep

2006

Jan

2007

Apr

200

7

Jul 2

007

Oct

200

7

Feb

2008

May

200

8

Aug

2008

Dec

200

8

Mar

200

9

Date

Ave

rage

Plu

me

Pt 1 Pt x

Figure 2-10: Plume Visibility Trend

The plume visibility observations since March 2005 have shown a slight downward trend. The average plume visibility varies between point 1 and point X due to the difference that the observers experience when looking into the plume. An observer at Point 1, which is at sea-level is looking through a greater length of the plume compared to the elevated observer at point X, which is at the top of the hill leading down to St Andrews beach. As the effluent becomes more dilute further away from the outfall, the number of observations decreases. Currently there is an area where observations generally occur. The boundaries of this area appear to correspond with a mean dilution of 50:1 to 100:1. Based on research that has been undertaken by Melbourne Water and South East Water (see later in this section), these dilutions correspond with the point where current effluent colour levels that would be expected to be barely visible compared with the background marine environment. The clarity of the water is a measure of how clear the water appears and is a combination of both suspended solids, (caused by the natural marine processes and the suspended solids & turbidity in the ETP effluent) and true colour of the effluent. Figure 2-11 below charts the monthly average observations (where 1= clear water, 2=slightly turbid, 3=highly turbid, 4=dark appearance).

72 Melbourne Water

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Feb-

05

Apr

-05

Jun-

05

Jul-0

5

Sep

-05

Nov

-05

Jan-

06

Mar

-06

May

-06

Jul-0

6

Sep

-06

Nov

-06

Jan-

07

Mar

-07

May

-07

Jul-0

7

Sep

-07

Nov

-07

Jan-

08

Mar

-08

May

-08

Jul-0

8

Sep

-08

Nov

-08

Jan-

09

Mar

-09

DATE

AVE

RA

GE

CLA

RIT

Y

Boags Rocks outfall (car park) St Andrews 500m west of outfall St Andrews 250m west of outfall

Gunnamatta 250m east of outfall Gunnamatta 500m east of outfall

Figure 2-11: Water Clarity Trend

At the outfall carpark (Point 1) the clarity is generally worse than for the other locations where the observations are made, which are some distance along the beach away from the discharge point. At the outfall the clarity of the water is generally described as being ‘slightly turbid’ and there is no clear trend over the period of the observations that suggests any significant change in water clarity. At the other locations the clarity is generally described as ‘clear water’ with the clarity improving away from the outfall (points 3 and 5 which are 500m away from the discharge). This suggests that the ETP discharge, particularly the colour and suspended solids in the water are having an impact on water clarity in the receiving environment. The current secondary effluent discharged at Boags Rocks is a yellow/brown colour and contains suspended solids and turbidity, at levels typical of a secondary treatment plant effluent. The effluent typically has a true colour of 90 Pt-Co units, with peak levels of around 140-150. The level of suspended solids in the current secondary effluent is around 16 mg/L (peak 30-40), and the turbidity is approximately 5-8 NTU (peak around 20).


The true colour of seawater has been measured at 2 Pt/Co and turbidity has been measured as 0.5 NTU. Both of which are significantly lower than the colour and turbidity of the current secondary effluent. In order for the plume to not be visible the colour of the discharge needs to be closer to that of the marine environment and this can be achieved either through increasing the dilution of secondary effluent with the seawater, or through reducing the colour and turbidity of the treated water being discharged. Source control has been investigated as a means of reducing the level of colour removal treatment required. The work, principally carried out by South East Water, has included: • Development of colour science methodology to overcome some limitations with

colour tests historically used to monitor trade waste customers • Collating colour data from routine monitoring required in existing trade waste

agreements for customers identified as potential colour sources • Further sampling to ensure all industry categories in the ETP catchment had been

assessed for colour discharge • Analysis of the combined data set to identify key sites for colour discharge • Intensive composite sampling of top 14 customers to assess average and peak

impact on ETP effluent colour. This includes biodegradation of samples in the laboratory to mimic what occurs through the ETP treatment process, and hence measure the colour that would potentially remain in the treated effluent.

• Establishment of waste minimisation investigations to identify the practical opportunities to reduce colour, the associated costs and the benefits.

This work has indicated that the difference between the current ETP effluent true colour levels (median 90 Pt/Co units), and that which would be expected from a plant with a totally domestic/commercial catchment (around 60-70 Pt/Co units), can be potentially explained by the trade waste sources. The work has also indicated that the variability in ETP colour levels (range of 60 to a peak of around 140-150) can be potentially explained by the variability in trade waste colour contribution. The information on waste minimisation opportunities, costs and benefits will be integrated with the detailed design phase of any colour removal treatment upgrades at ETP to determine the most appropriate balance of treatment and source control, considering issues such as lowest community cost and energy. It is important to note that source control alone cannot reduce colour levels below what would typically be found from a purely domestic catchment, and at best can only improve the average colour levels in ETP effluent by around 20-25% (peak levels

74 Melbourne Water

might be reduced by a higher %). This means that source control alone cannot offer sufficient reduction to reach background colour levels in seawater. Research by South East Water using colour science technology commonly used in the textile industry to determine how close a match various colours are, has suggested that for it to be difficult for an observer to distinguish the difference in colours it is likely to require a ‘just noticeable’ to ‘very close’ match. Table 2-5 below shows the results, indicating the range of treated water colour and dilutions that are needed to achieve these outcomes so that the discharge is not distinguishable from the colour of the seawater. Table 2-5: Observed colour and dilutions with seawater

Description of

observable colour

difference

Dilution Colour of treated water (Pt/Co units) that can

be diluted by the factor in column 2 and meet

the observable colour difference in column 1

1 in 50 90 Just noticeable

1 in 20 30

1 in 50 140

1 in 20 60

Very close match

1 in 10 20

1 in 50 > 140

1 in 20 120

1 in 10 70

Close match

1 in 5 30

Very noticeable 1 in 5 120

To achieve a mix where the ETP treated water colour cannot be distinguished from the seawater, for a dilution of 10:1 (as typically achieved within 70-100 metres of the discharge point) the treated water colour will typically need to be around 20 Pt/Co, whereas if the dilution is higher, the treated water colour could be correspondingly higher. It appears from this work that with current effluent colour, observations of the plume can in theory still occur at locations with modelled average dilutions up to 50:1, particularly for peak effluent colour levels. Review of the beach observation data at different points appears to support this, as mentioned earlier. The calculated colour and turbidity at the outfall at a distance of 20m and 250m along the shore in either direction is higher than the background level based on dilutions


from the hydrodynamic model and current effluent quality, which supports the beach observation data which indicates the plume is visible along this section of coastline. Colour related plume visibility is expected to be minimised with current effluent colour levels once mean dilution reaches around 50:1, or through a combination of colour reduction by treatment and the existing dilution levels. This is also supported by a simple trial undertaken by Melbourne Water in 2002 comparing the ETP effluent, filtered ETP water, ETP secondary effluent diluted to 50:1 with seawater and seawater at Rye surf beach. A photo from this test is included below. The 50:1 diluted effluent has a similar colour to the seawater, which also confirms the findings from the South East Water colour science work.

Figure 2-12: Comparison of L to R - ETP effluent, ETP membrane filtered effluent, filtered effluent diluted (50:1) with seawater and seawater with no effluent.

Colour is not the only cause of plume visibility. Suspended solids from both the secondary effluent and turbulence in the marine environment also contribute. Suspended solids and turbidity levels will rise when waves and currents stir up sediment as part of the natural marine processes. Water at a beach even unaffected by an effluent discharge can appear to have variable colour and turbidity due to these effects.

76 Melbourne Water

The sediment surrounding Boags Rocks may include some organic material that has been deposited from the secondary effluent over time and this may also be resuspended which can contribute to plume visibility. The ANZECC guidelines (2000) recommend that for marine waters, clarity should not be allowed to change by more than 20% from natural conditions. This guidance is primarily to protect the safety of swimmers if they are diving or swimming in a water body. Again this objective can be achieved either through increasing dilution or providing treatment to reduce the colour and turbidity of the treated water prior to it entering the environment. When effluent quality and mixing conditions are such that a visible plume is likely, the degree of visibility is also influenced by the local conditions such as the amount of waves, the level of cloud cover, and the location of the observer. This has been confirmed with results from the beach observations. There is a small residual risk of an area (radius of 10’s of metres) of plume discernibility, under the very rare low mixing conditions, that may be caused by the freshwater ‘floating’ on the seawater due to density differences, even if the colour and turbidity has been removed. This is considered to be a low risk even for those scenarios with the current outfall, and is highly unlikely to be considered objectionable by observers. The factors which influence the visible impact on the receiving environment also influence the ability to utilise the treated effluent resource in recycling applications.

2.6.8 Customer Perceptions of Treated Water Quality

Recent customer research2 into the acceptability of using recycled water in the home, has shown that the aesthetics of the recycled water such as colour and odour are likely to have an impact on peoples’ acceptance of the water. This has been demonstrated in various studies, and most recently customer research undertaken by South East Water in early 2009, which shows that as the colour of the water increases, people are less likely to accept this for both clothes washing and toilet flushing. Concerns about the colour were related to the risk of staining clothes and the perception that the toilet was ‘unclean’. Figure 2-13 and Figure 2-14 show the acceptability of the various recycled water colours (in Pt-Co units, on the X axis) for the uses of toilet flushing and clothes washing.

2 NWC Opinion Research – “Customer Response To Water Colour Research 2009”


The median colour from ETP at present is approximately 90 Pt/Co units, and the 90th percentile is approximately 120 Pt/Co units. Advanced tertiary treatment that includes ozone/biological media filtration (as discussed in Section 4) is capable of producing water with a median colour of < 15 Pt/Co units. (Note: For a point of reference, a colour of 15 Pt/Co is the upper value recommended for potable water supplies in the Australian Drinking Water Guidelines.)

Toilet

98%89%

53%40%

28%

0%0%

2%

3%

2%

0%6%

18%

18%

14%

2% 5%

27%39%

56%

0%

20%

40%

60%

80%

100%

10 20 60 90 140

Perc

enta

ge o

f Res

pond

ents

Acceptable - Both Acceptable - Tap only Acceptable - Alternative only Not Acceptable

Figure 2-13: Customer Research - Acceptability of recycled water colour levels from 10 to 140 for use in Toilet Flushing

The 378 survey respondents were asked to view the colour in each of the toilet bowls and rank the acceptability of each of the coloured waters for use in clothes washing and toilet flushing. They were asked if the source of the water (whether it was recycled water, or tap water) would change the acceptability of the coloured water. ‘Acceptable Tap’ was to describe the water if it came direct from the tap (i.e. potable water), ‘Acceptable Both’ was used to describe the water if it came from either the potable supply or from an alternative source such as recycled water. These results show that for a colour of 10Pt/Co, 98% of people surveyed thought the water to be acceptable for use in flushing toilets, whereas only 40% thought a colour of 90 Pt/Co would be acceptable. This drops even further to only 28% of people accepting water with a colour of 140 Pt/Co.

78 Melbourne Water

Washing Machine

95%

74%

24%14% 9%

1%

2%

2%5%

2%

2%

4%

7%6%

5%

3%20%

67%74%

84%

0%

20%

40%

60%

80%

100%

10 20 60 90 140

Perc

enta

ge o

f Res

pond

ents

Acceptable - Both Acceptable - Tap only Acceptable - Alternative only Not Acceptable

Figure 2-14: Acceptability of recycled water colour levels from 10 to 140 for use in Clothes Washing

A similar trend in acceptability can be seen with the colour of water when customers were asked about it’s suitability for clothes washing. Other concerns raised by those surveyed were the perceived health risks from using water with a colour greater than 20 Pt/Co units, reinforcing the long held community perceptions of coloured water being ‘dirty’. Similar results have been found from other customer research studies in South Australia, that colour and odour of the recycled water, even though it may be ‘fit for purpose’ from a microbiological standard, will reduce customer acceptance of the water. Water with an appearance that may remind consumers from where it has come (i.e. a sewage treatment plant), due to an odour or colour, is less likely to be accepted for non potable uses compared to water where its origins are less clearly defined. Providing a treatment process capable of reducing the colour down to levels where there is stronger community acceptance of the recycled water, around the 20 Pt/Co level, will assist in the maximisation of the use of this water resource.


2.6.9 Beach Litter

Litter is reported at the beach, notably ‘cotton bud’ sticks, sanitary gauze and small pieces of plastic. These appear somewhat sporadically, and are more commonly found to the west of the outfall rather than to the east. Pieces of litter are collected and counted during beach inspections on St Andrews and Gunnamatta beaches. Analysis of the beach observation data from March 2005 to January 2009 shows the following: • For St Andrews observations some 500m west of the outfall, no cotton bud sticks

were observed on 22% of occasions and less than 10 cotton bud sticks were observed on 88% of occasions. No plastic strips were observed on 75% of occasions.

• For Gunnamatta observations some 500m east of the outfall, no cotton bud sticks were observed on 80% of occasions and less than 10 cotton bud sticks were observed on 99% of occasions. No plastic strips were observed on 93% of occasions.

The difference in litter being collected between Gunnamatta and St Andrews beach has not been fully explained. It could be due to the geomorphological formations on either side of the outfall influencing where the material remains on the beach. Instances of high counts of litter such as cotton bud sticks appear to sometimes occur with no obvious event at ETP that would explain the increase.

2.6.10 Foam

Foam is caused by the presence of surface active and foam stabilising agents in the ocean. Foam is naturally present at times on ocean beaches, but reported observations suggest foam near the outfall is often coloured and sometimes has an odour. There are various constituents in the effluent which could possibly be a cause of this more common and persistent foam. Surfactants in the water can come from biological sources (such as bacteria) in the marine environment or from residual surfactants such as soaps and detergents not fully removed by treatment which may be present in the effluent from ETP. Alternatively foam can be derived from the biological treatment processes at the treatment plants. Foam forming bacteria (known as Gordonia Amarae like organisms or ‘GALO’) are an essential part of the biological population in the secondary treatment process and cause foaming in the activated sludge process. It is possible that the GALO are contained within the secondary treated effluent and transported to the marine

80 Melbourne Water

environment and with the additional mechanical energy from the ocean are again able to produce stable foams. Foam is formed from froth. Froth is caused by mechanical energy, from the natural marine conditions of wind and waves causing air to become entrained within bubbles, which is part of the natural marine processes. As the liquid drains from the bubbles, foam can then form. Foam is produced when each bubble is separated from its neighbour by only a thin film of liquid. Foam becomes stable when surfactants are present and can persist for long periods of time. Therefore, ‘persistent’ foam at the shoreline must have been influenced by surfactants, and possibly agents which stabilise the foam. Oils and greases may be linked to foaming by providing a substrate for the growth of hydrophobic foaming bacteria. High oil and grease levels may provide an advantage to these microbes, allowing them to grow to larger populations and thus resulting in more foam. Figure 2-15 below charts the monthly average observations, where 1=none present, 2=small amount - breaks down quickly, 3=moderate amount - starting to form piles, 4=significant amount - forms piles > 0.1m.

0.60

0.80

1.00

1.20

1.40

1.60

1.80

2.00

2.20

2.40

Feb-

05

Apr

-05

Jul-0

5

Sep

-05

Dec

-05

Mar

-06

May

-06

Aug

-06

Nov

-06

Jan-

07

Apr

-07

Jul-0

7

Sep

-07

Dec

-07

Feb-

08

May

-08

Aug

-08

Oct

-08

Jan-

09

Apr

-09

DATE

AVE

RA

GE

FOA

M

Average of: St Andrews 250 west, Boags Rocks outfall, & Gunnamatta 250 eastAverage of: St Andrews 500 west of outfall & Gunnamatta 500 east of outfall

Figure 2-15: Beach Foam Observation Trend


Comments regarding the quantity of foam at the various observation points are as follows: • The quantity of foam is observed as small or greater on 80% of beach observations

at Boags Rocks. Of these, less than 20% of observations are moderate or significant.

• The foam is observed as small on 30% of beach observations at St Andrews 250m from the outfall. Less than 3% of observations are moderate. The quantity of foam is observed as small on 20% of beach observations at Gunnamatta 250m from the outfall. Less than 3% of observations are moderate or significant.

• The foam is observed as small on 20% of beach observations at St Andrews 500m from the outfall. A few observations are moderate or significant. The foam is observed as moderate on less than 18% of beach observations at Gunnamatta 500m from the outfall. A few observations are moderate or significant.

On average there is a small amount of foam present but it breaks down quickly, or there is none present. There is generally more foam present nearer to the outfall compared with the observation points 500m away from the discharge point either side of Boags Rocks. In previous studies by CSIRO a common link between foam, odour and plume visibility was made through the beach observation data. This may explain the commonality in trend for these 3 aesthetic parameters over the past 12 months.

2.6.11 Oil and Grease – Fat Balls

Oil and grease is found in sewage from domestic, commercial and industrial sources. It arises from soaps used domestically and for many cleaning processes, as well as vegetable and animal oils inherent in our diets and used for cooking. Oil and grease is different from other constituents of sewage in that it is sparingly soluble owing to its hydrophobic nature. In recent years tests typically do not detect oil and grease in the current effluent from ETP at the standard limit of detection, i.e the median is <5 mg/L. The 90th percentile over the long term (February 1993 to January 2008) is 16 mg/L, but more recently the 90th percentile measured oil and grease is 5 mg/L (over the period January 2004 to April 2009). A range of treatment improvements and source control measures are believed to have contributed to this improved control of effluent oil and grease levels. The sporadic and low level nature of this effluent parameter makes it difficult to correlate with beach observations.

82 Melbourne Water

Residual oil and grease is believed to be responsible for the formation of small fatty particles, (known as fatballs or soap balls), occasionally found on the shore near the outfall. The formation of fatballs is not fully understood but believed to occur when existing smaller particles agglomerate or dissolved oil and grease precipitates and combines to form larger, insoluble particulates of oil and grease. During beach walks respondents were asked to rate the amount of soap/fat balls as none, few or lots, with the largest specimens having a diameter of a few mm. Analysis of the beach observation data from March 2005 to January 2009 shows the following: • For St Andrews observations some 500m west of the outfall, no fat balls were

observed on approximately 80% of occasions and fat balls mostly small were observed on approximately 20% of occasions.

• For Gunnamatta observations some 500m east of the outfall, no fat balls were observed on 96% of occasions and fat balls mostly small were observed on 4% of occasions.

Occasional attempts to analyse particular samples have indicated the presence of fatty acids, as may be derived from soap or dietary fats. The reported fat-balls from beach walks have, however, not been routinely subjected to laboratory analysis, and it is very difficult to determine the makeup of a fat-ball from simple observation (it can easily be confused with pumice, sand or even surfboard wax).

2.6.12 Odour

There are a range of influences contributing to odour generation at the discharge point, including the dissolved compounds in the effluent, the wind and sea state which assist in the dispersion of the odour, as well as foam which has previously been identified as an odour source itself from the beach inspection logsheets. In addition to being an actual source of odour, the fact that foam can be seen leads to a greater perception of an odour associated with it. Air entrainment in both the outfall pipe and the marine environment both assist in the odour being dispersed into the environment. The odour creating compounds in the effluent are dissolved substances that are derived from products used both domestically and commercially and include such things as fragrances from soaps and cleaning products. The other source of odour creating compounds is the by-product of bacterial action, such as occurs in the wastewater treatment process, which leads to an earthy or musty odour character.


The diagram in Figure 2-16 below illustrates the conceptual model of the linkages between these factors.

Figure 2-16 Linkages between factors associated with odour at the discharge point

Figure 2-17 below charts the monthly average odour observations from the beach inspection program, where 1= not noticeable, 2 = faint, 3 = moderate, and 4 = strong.

0.8

0.9

1.0

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

Feb-

05

Apr

-05

Jul-0

5

Sep

-05

Dec

-05

Mar

-06

May

-06

Aug

-06

Nov

-06

Jan-

07

Apr

-07

Jul-0

7

Sep

-07

Dec

-07

Feb-

08

May

-08

Aug

-08

Oct

-08

Jan-

09

Apr

-09

Date

AVE

RA

GE

OD

OU

R

Average of: St Andrews 250m west of outfall, Boags Rocks outfall, & Gunnamatta 250 east of outfallAverage of: St Andrews 500m west & Gunnamatta 500 east of outfall

Figure 2-17: - Odour Observation Trend

Based on observations from the beach inspection logsheets over the period from 2005-2009:

84 Melbourne Water

• At Boags Rocks, odour has been observed for 41% of beach observations. Of these, 30% of observations were faint, 9% were moderate, and 2% were strong.

• At St Andrews 250m west of Boags rocks, odour has been observed for 32% of beach observations. Of these, 15% of observations were faint, 5% were moderate, and 2% were strong. Odour observations were practically non-existent further away from the outfall at St Andrews 500m west of Boags Rocks with a faint odour only being detected for 2% of observations.

• At Gunnamatta 250m east of Boags rocks, odour has been observed for 15% of beach observations. Of these, 10% of observations were faint, 4% were moderate, and 1% were strong. Odour observations were practically non-existent further away from the outfall at Gunnamatta 500m east of Boags Rocks with a faint odour only being detected for 2% of observations.

Odour at the outfall has improved in recent years and this is believed to be due to improvements to the aeration process in the secondary treatment area at ETP. The reduction in odour in recent months also correlates with a slight reduction in foam observations which supports the theory that foam and odour observations are related. As the observer moves away from the discharge point (points 3 & 5) the odour is generally not noticeable. This would be due to increase dispersion of the odour in the atmosphere.

2.6.13 Recreational Water Quality

Monitoring of microbial quality for beach (shoreline) sites local to the discharge point has been carried out since ETP was commissioned in 1975. Over the last 10 years monitoring has been extended to cover surf zone sites as well as beach sites. Results are assessed with reference to EPAV policy and licence, and the National Health & Medical Research Council’s “Guidelines for Managing Risks in Recreational Water”. Regulations for recreational water quality generally accept a higher level of tolerable risk for recreational bathers compared with other activities such as drinking water. Tolerable risk of gastrointestinal disease per bathing event is 1:100. Tolerable risk of illness from drinking water for a year is 1:1,000,000 (WHO). A desktop review by Monash Department of Epidemiology and Preventive Medicine in 1998 concluded based on indicator organisms that the Gunnamatta Beach was relatively clean and there were unlikely to be increased health risks to those persons using Gunnamatta Beach compared to swimmers at other ocean beaches.


The more recent application of QMRA principles to consideration of this issue provides an additional layer of information on specific pathogen risks and episodic risks, and has indicated that for the current treatment and outfall arrangements: • QMRA supports the NHMRC classification at the risk level of ‘Good’ • Principal drivers of the calculated risk are Norovirus and Cryptosporidium • During high flow operating conditions, risks may be elevated during and following

the event • More sampling is required during wet weather events to fully characterise the risk

to recreational users of the environment around Boags Rocks under peak flow operating conditions at ETP.

2.7 Key Conclusions

• An extensive program of consultation, environmental monitoring and scientific investigations has been carried out to inform an assessment of the impacts associated with the discharge of secondary treated effluent from ETP the marine environment at Boags Rocks.

• This investment in understanding has underpinned the current ammonia reduction upgrade to the secondary treatment process, and now forms the basis for the next round of improvement. The studies have included: • Marine surveys and biological monitoring • Effluent quality and receiving waters monitoring programs • Recreational Health Risk assessments • Bioaccumulation studies • Beach and water quality assessment for aesthetic/amenity impacts • Hydrodynamic modelling to assess the dispersion of treated effluent • Assessment of acute and chronic toxicity using sensitive species from different

levels of the marine biological structure • Melbourne Water now believes it is well informed to assess the current discharge

arrangement and the likely improvements that the various upgrade scenarios have to offer.

• Monitoring at intertidal rocky platforms along the coastline between Point Nepean and Cape Schanck has shown a loss of brown algae such as Hormisira Banksii and Durvillea potatorum at Boags Rocks and Fingals. The Boags Rocks area has been recolonised with turfing green algae (Ulvales), mussel (Brachydontes) and a spionid worm (Boccardia proboscidea). The suspended solids in the current secondary effluent provide a significant food source e.g. for the Boccardia, and has encouraged this colonisation within 150m of the discharge point.

• At Fingals an increase in red turfing algae has occurred. It has been hypothesised that nutrient enrichment favours these turfing algae. There was little change

86 Melbourne Water

between 2001 and 2007, however there has been evidence of Hormisira Banksii recolonising on the rocky platforms at Fingals beach in the 2009 survey.

• The ammonia reduction process at ETP was been commissioned in late 2007. Effluent ammonia levels since the upgrade have averaged around 3 mg/L (15-25 mg/l prior to the upgrade) and Total Nitrogen around 17 mg/L (25-35 mg/l prior to the upgrade).

• No 16 and St Johns Wood (7.5, 14km NW of discharge point) appear unimpacted. There are no intertidal rocky platforms between Number 16 and Boags Rocks which provide suitable habitat for H. Banksii. There are no intertidal rocky platforms between Boags and Fingals which provide suitable habitat for H. Banksii..

• Offshore surveys showed rich flora and fauna are present and a health subtidal community.

• Levels of heavy metals and organic toxicants measured in seawater are low and bioaccumulation of the contaminants measured in seafood does not appear to be significant, making them suitable for human consumption.

• Ongoing testing has confirmed ammonia as the key cause of toxicity. Whole effluent toxicity testing has shown that as ammonia levels have been reduced in the effluent, the toxicity has also reduced.

• H. Banksii (early life stages) is the most sensitive species to ammonia and historical effluent ammonia levels would have likely impacted at Boags Rocks. Where ammonia is <5 mg/L the safe dilution by seawater is 20:1. H. Banksii. is relatively unaffected by fresh water (when ammonia is removed effects are only observed at dilutions of <4:1).

• Freshwater does not appear to exacerbate the impact of ammonia (i.e. there are no synergistic impacts between freshwater and ammonia). The most sensitive species to freshwater is scallop larval development, where effects may be seen at dilutions <20:1.

• The aesthetic impacts at Boags Rocks and the surrounding environment include plume visibility and water clarity, oil & grease related ‘fatballs’, foam, litter and odour. An extensive beach walk observation program and development of conceptual models of causal factors allow assessment of the key mechanisms behind these impacts.

• The presence of these aesthetic/amenity impacts is inconsistent with community expectations and policy guidelines. These impacts are most noticeable closest to the discharge point and can extend to around 700-800 m from the outfall, albeit much reduced with distance.

• Plume visibility and water clarity is influenced primarily by dissolved colour, turbidity and suspended solids levels in the discharge.

• Colour is also a significant influence on the perceptions of recycled water customers, who show low levels of acceptance of the current effluent colour levels.

• Targets for colour and suspended solids reduction to address plume visibility and


water clarity impacts, and achieve high levels of recycled water customer acceptance have been derived.

• Oil & Grease (fatballs) are found infrequently and believed to be caused by particulate oil and grease combining to form larger particles which become stranded on the tidal lines along the beaches.

• Litter of treatment plant origin includes items such as cotton bud sticks, small plastics and small pieces of sanitary gauze. They appear somewhat sporadically and are more common to the west rather than the east of the outfall. The level of litter on the beaches is generally low with less than 10 cotton bud sticks observed on 88% of occasions on St Andrews beach, and no cotton bud sticks are found on Gunnamatta beach on 80% of occasions.

• Foam that is caused by the biological processes in treatment plants, rather than the typical white foam from marine processes, is generally of a brown colour and persists for longer duration. Small quantities of foam are observed on around 80% of occasions at Boags Rocks.

• A common link between foam and plume visibility and odour has been found and these three have shown similar trends.

• An odour similar to secondary effluent, and often showing earthy-musty characteristics, is observed in the area immediately surrounding Boags Rocks around 40% of the time. Odour falls off significantly with distance from the outfall, with observations less than 5% of occasions at a distance of 500m.

• Monitoring of the microbiological quality of the beaches local to the discharge has been carried out since ETP was commissioned in 1975. In the last 10 years the monitoring has been expanded to also cover surf zone sites as well as beach sites.

• The Australian Government publishes the ‘Guidelines for Managing Risks in Recreational Water’ (NHMRC 2008) and based on long term monitoring results for key microbiological indicators the beaches and surf zone around Boags Rocks and Gunnamatta beach consistently achieve a Good to Very Good risk classification.

• To account for event based risks a Quantitative Microbial Risk Assessment was undertaken which showed that under dry weather operating conditions at ETP that the risk level is consistent with NHMRC classifications of ‘Good’ however under peak wet weather conditions (beyond the 99th percentile flow) the risk may be elevated.

88 Melbourne Water

There have been significant changes to the strategic environment and

influences on decision making since the initial Works Approval for the ETP

Upgrade. These include policy and regulatory interpretation applicable to the

project, and within the broader environmental context.

Melbourne Water has also undertaken a wide range of additional studies to

better inform the decision making process, and there is now a clearer

understanding of the interaction between ETP operations and the receiving

environment, and the community expectations for sustainable water cycle

management.

This section outlines these influences and provides an appropriate lead in to

subsequent sections where the most appropriate means to address the issues

discussed in the previous sections is considered.

3.1 Climate Change & Water Resources Outlook for the Central Region

Since 2001, the concept of Climate Change due to increases in greenhouse gases in the atmosphere has become widely accepted amongst both the scientific and general community. Research also suggests that the observed changes to temperature and seasonal rainfall patterns, and the associated reductions in streamflow, particularly over the last decade in Victoria may be in part due to global warming (see http://www.mdbc.gov.au/subs/seaci/index.html for further references). Below average rainfall has been recorded since 1996 with 2006 experiencing the lowest year of streamflow on record. This has lead Melbourne to being on permanent water saving rules and water restrictions for potable water use, which apply to water use outside the home. There are also restrictions and bans in place on diversions for irrigation and commercial use from many waterways. Since 1997, the average inflows into Melbourne’s main water supply reservoirs have been more than 38% below the long-term average observed over the period of historical records from 1913. The period from 1997 to 2008 saw three major drought years in 1997/98, 2002/03 and 2006/07 and no year in which annual inflow was higher than the long-term average. Inflows in the calendar year of 2006 were the

3. Strategic Context for Decision Making

http://www.mdbc.gov.au/subs/seaci/index.html


lowest in almost 100 years of recorded history. There is no definitive evidence to suggest that there will be a return to higher rainfall conditions and inflows that are consistent with long-term averages, or that conditions will continue as per the last decade. As a result, there is considerable uncertainty regarding the future streamflow planning scenarios. Recent bushfires have burnt through approximately 30% of Melbourne Water’s catchments, which is also expected to result in longer term changes to catchment runoff conditions whilst the forest regenerates. Whilst there may be increased runoff in the short term, as the forest regenerates over time it is expected that regrowth will reduce yields and inflows from the fire affected areas. This may influence long term water availability and the subsequent timing and quantities required in water supply augmentations beyond the reintroduction of Tarago Reservoir into supply in mid 2009, the Sugarloaf pipeline, and the introduction of supplies from the Wonthaggi desalination plant. Melbourne’s storage reserves have fallen from near 100% capacity in 1996 to a record low of 26.0% capacity in early July 2009. In the calendar years of 1997 and 2006, storage levels fell by 24% and 20% of full supply capacity in each respective year. Furthermore, there was little storage recovery in the majority of intervening years, with storage levels at the end of each year being largely the same, if not worse, than storage levels at the start of that year. There were only three years in this 10 year period where storage levels improved during the course of the year, and in each case, the increase has been marginal, with storage levels rising only 3% of full supply capacity in 2000, 5% in 2003 and 4% in 2004. Melbourne is not alone with observed reductions in rainfall and inflows to its major water supply catchments. Yearly inflows into Perth’s reservoirs from 1911 to 1974 averaged 338 gigalitres, but from 1975 to 1996 yearly inflows averaged 177 gigalitres, and from 1997 to 2005 yearly inflows averaged 114 gigalitres. Research suggests that for south-western Australia, both climate change and natural variability are likely to be contributing to the changes in climate and the associated shift in streamflows, along with other key climate drivers such as the El Nino-Southern Oscillation (see http://www.mdbc.gov.au/subs/seaci/docs/factsheets/SEACIfactsheet-climate.pdf).

90 Melbourne Water

It is possible that a similar “shift” has also occurred in Melbourne and that it is no longer prudent to rely on long-term observed inflow trends3. Probabilistic assessments undertaken by Melbourne Water on the basis of historical inflow data indicate there is a very low probability that an extended dry period such as that observed over the ten-year period from 1997 to 2006 would occur, yet it has4. The fact that such an extended dry period has occurred, and the fact that inflows during 2007 and 2008 to date align with this trend, supports the possibility that historical inflow data can no longer be relied upon to predict future inflow patterns. Research is ongoing to attempt to address the uncertainty of future inflows under climate change. Melbourne Water and CSIRO collaboratively undertook a landmark study regarding the impacts of climate change on Melbourne’s water, sewerage and drainage systems in 2005. Whilst the study acknowledged the range of uncertainties associated with climate change predictions, some consistent trends were developed for Melbourne. These trends included increased average and summer temperatures, reduced rainfall and more extreme weather events, meaning a greater number of hot and dry days and an increase in rainfall intensity during storms. The study projected that due to shifting rainfall and temperature patterns, long-term inflow for Melbourne’s water supply system would potentially reduce by between –3% to –11% by 2020 and between –7% and –35% by 2050. As discussed above, annual inflows observed over the past 12 years into our four major harvesting reservoirs have been around 38% below the long-term average, which is greater than the changes expected by 2050 under the high climate change scenario developed in the 2005 study. More recent climate change projections released by CSIRO and the Bureau of Meteorology in 2007 have updated regional projections developed in regards to annual warming, winter rainfall and annual potential evaporation by 2030 and 2070. There were minor variations in these updated projections in comparison to the 2005 study. These differences support the need to continuously review such projections and any significant implications for water resources. The Victorian Government is participating in a three-year research program, the South Eastern Australian Climate Initiative (SEACI), which is investigating the causes and impacts of climate change and climate variability across south-eastern Australia, including the impacts on water resources. The program commenced in 2006 and is

3 DSE, 2006 4 Tan and Rhodes, 2008


co-ordinated by the Murray Darling Basin Commission, with scientists from CSIRO and the Bureau of Meteorology undertaking the research. To date, SEACI has indicated that recent trends in rainfall and streamflow records appear unusual compared to records over the past 100 years and that these changes may be similar to those observed in south-west Australia from the mid 1970s. Further, SEACI has indicated that whilst research to date shows that climate change is expected to result in hotter and drier conditions across much of Australia, the observations over the past ten years are earlier and hotter than would have been expected. Results presented at the SEACI Annual Science Workshop in April 2008 also indicated that there is a high likelihood that the current rainfall deficit is linked to global warming. In light of the observed reduction in inflows sustained in recent years and the potential for on-going changes and variability in our climatic conditions, new water resources investment is needed. This is necessary to move away from relying on one major source of supply, currently being surface water reservoir supplies dependent on rainfall, to a more diversified portfolio of water sources including those which have less dependency on rainfall conditions. Climate change is not only having an impact on stream flows and water resources management. Sea level rise is another possibility with the projection of 0.8 metres rise by 2100 (to be assumed for statutory planning purposes based on the Victorian Government’s Coastal Strategy 2008). This may influence the rocky platforms at Boags Rocks that are currently in the intertidal zone and may progressively become submerged and no longer support the ecosystems which they do at present. The intertidal species will shift upwards to adapt to the increasing levels over time, but suitable habitat would presumably shrink. If the required underlying geology is present, coastal erosion processes may create new rock platforms, but this would presumably be a very much slower process than the sea level rise.

3.2 Streamflows and Impacts on Waterways Diverters

Climate change and reduced stream flows have not only had an impact on flows into Melbourne’s water supply catchments, but they have also had an impact on those people who use water from rivers, creeks and streams to support their livelihood. Irrigators throughout Victoria have been impacted by reduced streamflows including those around Melbourne who divert water from the rivers and creeks managed by Melbourne Water.

92 Melbourne Water

Recent information on streamflows shows that over the period from 2004 to early 2009, the number of waterways managed by Melbourne Water under restriction has remained around 5-10%. However the duration of these being under restrictions has increased from being predominantly during the summer months during the 2004-2006 period to increasing to almost continuously throughout the year since 2007. Although the 2006 calendar year was very dry, streamflows remained relatively consistent and it has been in subsequent years that streamflows have further declined, reducing water available for diverters. The percentage of waterways under Bans, (which means there is no water available for the diverters) has increased from around 30% in 2005 to approaching 50-60% during 2009.

Impact of restrictions and bans on waterway diversions

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Dec

-04

Jan-

05Fe

b-05

Mar

-05

Apr

-05

May

-05

Jun-

05Ju

l-05

Aug-

05Se

p-05

Oct

-05

Nov

-05

Dec

-05

Jan-

06Fe

b-06

Mar

-06

Apr

-06

May

-06

Jun-

06Ju

l-06

Aug-

06Se

p-06

Oct

-06

Nov

-06

Dec

-06

Jan-

07Fe

b-07

Mar

-07

Apr

-07

May

-07

Jun-

07Ju

l-07

Aug-

07Se

p-07

Oct

-07

Nov

-07

Dec

-07

Jan-

08Fe

b-08

Mar

-08

Apr

-08

May

-08

Jun-

08Ju

l-08

Aug-

08Se

p-08

Oct

-08

Nov

-08

Dec

-08

Jan-

09Fe

b-09

perc

enta

ge o

f wat

erw

ays

impa

cted

(%)

Percentage of waterways under restriction Percentage of waterways under licence ban

Percentage of waterways under bans Moving Annual Average

6 month moving avge

Figure 3-1: – Impact of drought/climate change on waterway diversions

The overall picture is thus one of diminished access to rainfall derived water resources whether for potable supply to a growing city, or for other uses such as industry or agriculture and food production in the region. The diversification of potential fit for purpose water resources, such as substitution of recycled water for non-drinking uses is hence an important opportunity to develop as demand grows.


3.3 Sewage Flow Trends for Melbourne

The main drivers of annual sewage volumes for Melbourne are: • Growth in existing retail customer discharges or connecting new customers

(including initiatives such as sewerage backlog programs) • Level of activity in industrial and commercial operations • Water conservation measures impacting on indoor household use (e.g. adoption

rates for water efficient appliances such as AAA washing machines and shower roses, customer education campaigns, greywater diversion measures, etc.)

• Rainfall, due to its impact on inflow and infiltration.

Water Consumed and Sewage Flows Collected for Treatment In Melbourne

0

40000

80000

120000

160000

200000

240000

280000

320000

360000

400000

440000

480000

520000

560000

1928

1931

1934

1937

1940

1943

1946

1949

1952

1955

1958

1961

1964

1967

1970

1973

1976

1979

1982

1985

1988

1991

1994

1997

2000

2003

2006

2008

Year

Ann

ual W

ater

or S

ewag

e Vo

lum

e (M

illio

n L)

0

50

100

150

200

250

300

350

400

450

500

550

600

650

700

Litr

es p

er p

erso

n pe

r day

Total Water Consumption

Total sewage volume (ML)

Sewerage (L/Person/day)

Water Consumption (L/Person/day)

Figure 3-2: Long term water consumption and sewage flows for Melbourne

The long term trend illustrated in Figure 3-2 above shows a number of interesting features: • The steady rise in both water consumption and sewage flows collected for

treatment up until the 1980’s as connected population rises through both population growth and the move away from septic tank systems in the built up urban area

• The sharp drops in response to drought years such as 1967 and 1982/3, when the sudden imposition of water restrictions (in times of sharp declines in the then

94 Melbourne Water

smaller storage volumes) altered customer behaviour and the level of groundwater infiltration and rainfall associated inflow.

• The upward trend in per capita sewage generation until the late 1970’s as rising affluence and lifestyle trends increase water use within the home.

• The significant trend downward in per capita water use and sewage collection from the 1980’s onwards as demand management programs such as community education and installation of water saving measures in the home begin to have their effect.

• The reduction in per capita figures more than offsets the increasing connected population, resulting in an ongoing decline in total volumes since the mid-90s

3.4 Sewage Inflows to the Eastern Treatment Plant

The recent trends in flows to ETP essentially follow that for Melbourne more broadly. A slowing in Melbourne’s population growth, and the success of waste minimisation, infiltration/inflow reduction, and water demand management measures from the late 1980’s onwards has seen the growth in flow to the plant slow dramatically and subsequently trend down. This of course translates to a lower effluent flow to the receiving environment than would have otherwise been the case. From early 1997 onwards, the operation of the sewage collection system has been managed to provide greater flexibility for switching some flows between the Western Treatment Plant at Werribee and Eastern Treatment Plant. This approach optimises system operation, wet weather flow management, and augmentation requirements over the next 20 years.


ETP Inflow (Million Litres per year)

70000

80000

90000

100000

110000

120000

130000

140000

150000

160000

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

Financial Year to 30 June .....

ML

Figure 3-3: ETP Inflow trend by financial year

Flow growth into ETP is declining as a result of drought and water saving being implemented across the catchment. Previous projections of flow growth have now been downgraded and flow projections are flat trending to decline. Projections from the retail water companies indicate that (assuming a given rainfall scenario from year to year) the total flows to ETP would be approximately 3000 ML lower in 2012/13 than 2009/10. The assumptions underlying the development of these forecasts for flows to ETP were: • A permanent decrease in domestic volume due to flow on effects from the

observed decline in water demand within households • Domestic volumes reflect population growth forecasts consistent with the water

demand assumptions • Industrial closures have not been factored into the analysis • Cleaner production initiatives have been factored into the forecasts • Further reduction in demand associated with the implementation of a real price

increase • Commercial and greasy waste will grow in proportion to domestic growth rates • Adjustments have been made for areas such as the central business district where

the population growth occurs elsewhere but contributions are made to flow and load growth in that area

96 Melbourne Water

• Discharges from trade waste customers reflect individual retail water business strategies but: - reflect the overall level of economic activity overlayed with the effect of cleaner

production initiatives - new customers are expected to employ water saving and waste minimisation

technologies • Inflow and infiltration remains at average levels as a result of the effects of ageing

sewers being offset by rehabilitation measures, new technologies and network expansion.

A further limitation on flow growth to ETP is the relationship of sewage to the water and recycled water cycles, and the location and form of urban growth areas. The Melbourne Metropolitan Sewerage Strategy is currently looking at these issues and how they affect potential flows to ETP. The Strategy’s analysis is illustrating that optimal sewerage servicing is linked to the potable water and recycled water strategies for the city. If water scarcity continues in Melbourne there will be continued calls for localised recycling of effluent in the city to provide fit for purpose water where it is demanded. This localised recycling is likely to be enabled by rapidly improving sewer mining and small scale sewage treatment systems. Actions to source water close to local demand may affect flow volume and quality at ETP for many years to come. Urban growth at the boundary of Melbourne to the North and South East is now entering land outside of the natural catchment of Melbourne and ETP. The cost of pumping and infrastructure required to service these areas is encouraging decentralised treatment, (rather than sending flows to ETP) to maximise the use of the water resource through local water recycling. Net treated effluent flows to the environment from the SEO are a function of inflows to ETP less recycling diversions, plus inflows less recycling from the three smaller treatment plants (at Somers, Mt Martha, and Boneo) operated by South East Water Limited. These plants contributed around 7.6% of the total volume discharged at Boags Rocks in 2007/08. SE Water’s primary focus has been to expand water recycling as a mechanism to reduce the discharge at Boags Rocks and to provide customer water solutions. The distributed nature of these plants, and proximity to potential customers, assists the development of a higher proportion of recycling of total flows. For the discharge volumes that do not currently have practical recycling opportunities, upgrades have


been targeted to match the previous ammonia reduction requirements in the Eastern Treatment Plant works approval (median ammonia < 5 mg/L). An outcome of the water recycling focus is that forecast volume to be discharged to the SEO is expected to decline after 2008/09 despite an increase in the population being served by the South East Water treatment plants.

Figure 3-4: South East Water Discharge Volumes to SEO

The forecast flows for these plants under average rainfall conditions are tabulated below.

2009/10 2010/11 2011/12 2012/13

Forecast Volume treated (ML) 10930 11280 11490 11750

Forecast Volume discharged (ML) 8860 8920 8480 7340 Table 3-1: Forecast Flows to SEO from SEWL

This focus has led to the following upgrade works that are either under construction or being planned:

98 Melbourne Water

3.4.1 Boneo Sewage Treatment Plant

Boneo currently contributes around 2.9% of the total outfall flow. However, this is expected to reduce to 0.7% by 2013 as substantial water recycling commences. A major upgrade to provide additional capacity, ammonia removal and to enable Class A water to be provided to local market gardens is under construction and will be completed in 2009. The EPA Works Approval for the upgrade was based on achieving a median effluent ammonia concentration of 2 mg/L. The Class A upgrade design has been focussed on meeting recycled water customer needs to ensure recycling is maximised and hence the quantity of water discharged to the South Eastern Outfall is minimised. The chosen tertiary treatment process involves ultrafiltration followed by ultra violet light and chlorine disinfection. The current works will provide sufficient tertiary treatment capacity for all dry weather flows. An allowance has been made in SE Water’s Water Plan submission for some further works to enable all wet weather flows to be tertiary treated. The treatment process does not specifically target colour, however Boneo effluent colour is low (around half that of the current ETP effluent) and given the small (and declining further via recycling) volume contributed by this plant, the water quality from the upgraded plant would not be expected to have a significant impact on the discharge at Boags Rocks (representing less than 3% of total colour loads to the discharge, even with advanced tertiary colour reduction implemented at ETP).

3.4.2 Somers Sewage Treatment Plant

A major recycling scheme has been approved by the state government for the Somers STP. Appointment of contractors is underway and an EPA Works Approval will be submitted in July 2009. This project will reduce the total volume discharged to the SEO from Somers STP by 40 to 50%. Hence Somers STP is likely to contribute less than 1% of the annual volume discharged to ocean from the South East Outfall. The recycling project involves supplying Class A water to BlueScope Steel. In order to meet the customer requirements, the treatment process will include Reverse Osmosis to reduce salt concentrations in water supplied to BlueScope steel. Hence, in future, flows from Somers will be pumped to the SEO in two streams: surplus treated effluent approximately six days per week and brine approximately 1 day per week. Impacts of this proposal on the SEO discharge have been assessed as negligible and will be further described in the separate works approval for the Somers STP upgrade.


The Somers STP pumps effluent to the SEO at a point near the Mt Martha STP. To take advantage of economies of scale, additional tertiary treatment of the small volume of Somers STP effluent that is not recycled is likely to be included in the scope of the tertiary treatment facility that would be provided at Mt Martha STP. Both colour and ammonia concentrations from the Somers STP are currently low (around half that for ETP), however colour concentrations (rather than loads) may change once the BlueScope recycling scheme is implemented. Like Boneo, Somers would represent less than 3% of total colour loads to the discharge, even with advanced tertiary colour reduction implemented at ETP.

3.4.3 Mt Martha Sewage Treatment Plant

The Mt Martha STP was upgraded in 2005 to reduce ammonia levels, with the upgrade targeting the performance levels in the previous ETP works approval. The plant currently meets an EPA licence limit of median 2 mg ammonia/L. An allowance has been made in the 2009-2013 Water Plan for a Class A upgrade of all flows discharged from the Mt Martha STP. Based on best available information at the time, costs for this upgrade were based on membrane filtration, UV and chlorine to achieve Class A standard. Once the preferred process for the ETP tertiary upgrade is approved, these assumptions may need to be revisited. Mt Martha effluent has a similar colour level to that at ETP. It may be possible to adopt a similar tertiary treatment train as at ETP and so achieve improved colour and ammonia removal; however the cost implications are unknown (albeit at a much smaller scale than ETP) and any decision to adopt tighter standards than already assumed would need to take into account the likely benefit given the small portion (less than 5%) of flow contributed by Mt Martha.

3.5 Declining Loads to the Environment

The changes in sewerage system inflows and operation and greater development of recycling, plus the implementation of ammonia reduction works at ETP and the three smaller SEWL plants, have direct benefits for the receiving environment. Figure 3-5 below illustrates this in the form of changing nutrient loads over time. The decrease in ammonia concentration in the effluent in recent years can be directly attributed to the upgrade to the secondary treatment area at ETP. The process was converted to a nitrifying/denitrifying process in late 2007 and has reduced ammonia in the secondary effluent entering the receiving environment by around 85%. The ammonia reduction project will be completed by early 2010 when aeration tank

100 Melbourne Water

capacity is increased by two-thirds with the commissioning of four additional tanks currently well advanced in construction. The potential implementation of advanced tertiary (as discussed in Section 4) which would offer further improvement to the point where net load reductions from the mid 90s would be approximately 60-70% and 98% for nitrogen and ammonia respectively.

Nitrogen Load to Marine Environment

0

1000

2000

3000

4000

5000

6000

1975 1980 1985 1990 1995 2000 2005 2010

Year

Tonn

es p

er Y

ear

NH3TN

Figure 3-5: Changing Nitrogen and Ammonia Load to the Marine Environment

3.6 Potential Recycling Outlook

There are many benefits of using recycled water, particularly for non potable applications that require a reliable and secure water source. Recycled water is an alternative water resource that is not dependant on rainfall or climate and the quality of the water is consistent all year round. It is generally sourced from sewage treatment plants and is treated to a level to make it ‘fit for purpose’ depending on the application and the risks of human contact with the water.


Given the impact of Climate Change and a reduction in streamflows, both local to the area of waterways managed by Melbourne Water and for those on a wider regional scale, there are many drivers for producing a water of high quality that can be used for a wide range of non potable applications. The salinity level of the recycled water from the Eastern Treatment Plant is suitable for existing uses for farming and dual pipe systems. The recycled water supply from the Eastern Treatment Plant provides a sustainable supply for irrigation purposes for the long term from a water quality perspective. Research over many years has shown a general trend toward the greater acceptability of using recycled water, and this is most likely driven by awareness of climate change and the limited potable water resource. Water restrictions highlight this and the community has developed a greater understanding of the water supply system, and more broadly acknowledge that at some point there will be a need to use alternative water resources which could include recycled water. Water recycling projects that in part substitute (on a fit for purpose basis) the use of potable water provide for greater flexibility in our capacity to manage the water supply-demand balance more sustainably in the future. Currently the community are comfortable to varying degrees with using recycled water for applications such as irrigation, toilet flushing and car washing, however there is a general trend as recycled water schemes evolve and all parties become more comfortable and trusting of the source of the water that more consumers will be willing to use the water for more personal uses such as clothes washing. This progression is influenced by customer perceptions of the quality of the product, which may go beyond the scientifically measured ‘safety’ of the water, and draw strongly on aspects such as aesthetic considerations such as the appearance of the recycled water. An example of recent research in this area is discussed in Section 2.6.8. Investigations by the Department of Sustainability and Environment have explored potential costs, benefits, and timing drivers for two very large scale water recycling projects - the Eastern Water Recycling Proposal, where water from ETP would be sent to the Latrobe Valley for use as cooling water in the power stations, and the Yarra River flow augmentation option, with recycled water from ETP boosting river flows downstream of the Yering Gorge Pump Station. The Yarra River option would allow more flow to be sustainably extracted from the Yarra River, upstream of Yering Gorge, for use as potable water.

102 Melbourne Water

Both of these schemes would require high quality recycled water, with the Yarra flows augmentation also requiring reverse osmosis and constructed wetland treatment (in addition to tertiary treatment) to address the particular background water quality requirements for the mid-Yarra. Either of these schemes would divert the vast majority of current dry weather treated effluent flows from ETP, but the business case for such large schemes and their associated high cost, and optimum timing for implementation, is dependent on the overall water resources supply demand balance for the region. Through substitution, both of these options have the potential to free up additional water resources for potable supply in the order of 60-70 GL per annum, should it be required in the medium to long term. In June this year the Minister for Water announced that the Government would not proceed with these two projects, as the business case investigations had found that the cost benefit balance for these projects was not favourable. An extended repeat of low rainfall and inflow years such as 2006 may speed the need to reassess the timing of the next major water supply augmentation beyond, say, the immediately identifiable option of upgrading the Wonthaggi desalination plant from 150 to 200 GL/year capacity, and continue the transition to a less rainfall dependent water supply over time. This can be readily considered as part of the regular (5 yearly) reviews of the Metropolitan Water Supply Demand Strategy and Central Region Sustainable Water Strategy (next due in 2013) where updated consideration of potential sources and uses of water in a strategic and integrated manner takes place. The cost to retrofit pipelines and distribution systems to the existing built-up urban area is high relative to the volumes used. Provision of recycled water infrastructure for new development areas is however much more cost effective. There are also social capital benefits for local communities in maintaining green open space and facilities such as golf courses, and returning sporting fields to full use through provision of recycled water. The further development of food-bowl projects close to Melbourne may have economic benefits and could reduce the carbon footprint of agricultural production due to a reduction in ‘food miles’ and the energy used to transport produce to the location of the demand for food. Other benefits include the value of nutrients in the recycled water in the cost of growing food.


Recycled water is used in operating the Eastern Treatment Plant instead of potable water that would otherwise be required. Off-site recycled water use from ETP totalled 7.9 GL for 2007/08, and was supplied to the Eastern Irrigation Scheme and to 45 South East Water customers who take Class C recycled water from various points along the South Eastern Outfall for agricultural and horticultural activities, including watering golf courses and sports fields, root crop irrigation, flower growing and drip irrigation of vineyards. South East Water (SEWL) are the recycled water retailer in the region around ETP and have commissioned further consultancies into potential recycled water applications in the south-east of Melbourne over a nominal 5-15 year horizon. The work has included: • A strategic scan to identify and rank recycling options, and • An economic study to identify economic costs and benefits of the more feasible

options identified in the strategic scan. The methodology for the strategic scan was: • Identify potential recycling options for Melbourne’s South East using input from

various stakeholders such as Councils, SE Water staff, other water authorities and relevant Government agencies

• This scan identified some 42 potential recycling options • These options were short-listed using criteria such as the scheme’s practicality,

consistency with government policy, and longevity (i.e. will the recycling option be available in the longer term)

• From this initial screening, a short list of 14 options was identified • Further analysis was then carried out on these short-listed options as a basis of the

report’s final recommendations. The options identified, and commentary on the potential outlook follows.

3.6.1 Schemes at Approved (or Approved-In-Principle) Stage

In addition to the 7.9 GL/year of current offsite recycling from the SEO, there are seven recycling schemes that have existing approval, or approval in-principle. Five of these are expected to deliver up to a total of 6.9 GL/year of recycling from the ETP. Two schemes will also deliver an additional 2.2 GL/year of recycling from SE Water’s Sewage Treatment Plants which also presently discharge to Boags Rocks. Hence schemes with existing approval or approval-in-principle are expected to ultimately deliver an additional 9.1 GL/year of recycling, further reducing the nutrient

104 Melbourne Water

and freshwater loads to the receiving environment at Boags Rock. However, the final volume of recycling and therefore reduction in outfall flows is dependent on factors such as climate conditions and customer use. Funding for the approved recycling schemes has already been committed by the various parties such as SE Water, Councils and the State Government. Further detail of recycling schemes at Approved or Approval-in-Principle stage is included in Table 3-2.

Recycling Scheme and End

use

Estimated

Potential

Volume

GL/Year *

Timeframe

**

Status of Scheme

Officer & Berwick Sth residential - dual pipe water supply

1.3 Long Mandated supply –

Business Case

submitted for approval Casey residential (Cranbourne and Hunt Club) - dual pipe water supply

2.8 Long Mandated supply -

Construction

Frankston Community recycling Scheme – public open space

0.07 Short Detailed Design

Mornington Rec recycling project - public open space and racecourse

0.3 Short Detailed Design

Dandenong Recycling Scheme. Industrial, residential (dual pipe water supply) and public open space

0.8

Short Business Case

approved. Commercial

agreements to be

executed Boneo Recycling Scheme - market gardens, recreational and public open space

3.2 Short Construction

Hastings Industrial 0.66 Short Detailed Design

Total 9.1 GL/yr

Table 3-2: Recycling Schemes that are Approved or have Approval-in-Principle

* subject to climate and customer uptake

** Short = < 5 years, Med = 5 to 10 years, long = > 10 years

3.6.2 Schemes at Feasibility Stage

Three schemes, outlined in Table 3-3 below, were identified that are at Feasibility Stage. These schemes do not yet have approval but they could move relatively


quickly to construction. The estimated volume of recycling from these projects is 1.3 GL/year, subject to climate and customer uptake, at a total estimated cost of $66M (based on an order of accuracy of plus or minus 25%). Based on a preliminary analysis, it is estimated these schemes would require around $40m of “up front” external funding to make them financially viable for SE Water to proceed with their construction. Further analysis is being carried out to establish a more accurate level of external funding. The Government has not committed any funding to these projects at this time.

Recycling Scheme and End Use Estimated

Potential

Volume

GL/Year *

Timeframe

**

Status of

Scheme

South East Community Water Recycling Scheme. Recreational, Council open space and residential (dual pipe water supply)

1.1 Short Preliminary

Functional Design

completed

Monterey Scheme Council open space

0.07 Short Feasibility

Patterson Lakes Council open space 0.1 Short Feasibility

Total 1.27 Table 3-3: Recycling Schemes that are at Feasibility Stage * subject to climate and customer uptake ** Short = < 5 years, Med = 5 to 10 years, long = > 10 years

3.6.3 Schemes at Concept Stage

Three schemes were identified in the GHD study as being at the Concept Stage. These schemes are Casey-Cardinia, Tyabb and new Casey Residential and are outlined in Table 3-4. Two of the concept schemes are potential food bowl schemes (Casey–Cardinia and Tyabb). The potential demand from these schemes could be up to 18 GL/year for the Casey-Cardinia scheme and 8.3 GL for the Tyabb scheme, depending on the region’s development and long term weather patterns and hence demand for irrigation. This is an upper estimate assuming full development of the food bowl schemes. By comparison, the Werribee Irrigation District currently uses some 16 GL/year of recycled water. As both foodbowl schemes are at Concept Stage, significant further investigations are required to support decision making. There are a wide range of issues that would need to be addressed in order to successfully deliver the identified recycling schemes.

106 Melbourne Water

For example, appropriate planning overlays and infrastructure to support horticulture intensification. The delivery of recycling infrastructure is only one component of this broader picture and therefore further investigations and feasibility studies would need to: • Assess policy and Planning positions in relation to establishment of intensive

agriculture at the urban/rural interface • Prepare preliminary designs for the schemes, including identification of support

infrastructure that may be required, and more detailed costings • Undertake a more detailed assessment of potential scheme demand • Establish staging options for development of the schemes The third concept scheme identified is the new residential precinct in Casey, which was established by the proposed change to the Urban Growth Boundary. The potential volume of reuse is estimated at up to 5.3 GL/year. If it were to proceed, it is likely to be mandated consistent with other residential dual reticulation schemes. This demand would not come on stream until the area is developed, perhaps in 10 to 20 years time.

Recycling Scheme and End

Use

Estimated

Potential Volume

GL/Year *

Timeframe

**

Status of

Scheme

Casey – Cardinia Foodbowl 18 Medium -

Long

Concept

Tyabb Intensive Agriculture Zone

8.3 Medium -

Long

Idea

New Casey Residential (dual pipe water supply)

5.3 *** Long Concept

Table 3-4: Recycling Schemes that are at an early Stage * subject to climate and customer uptake ** Short = < 5 years, Med = 5 to 10 years, long = > 10 years *** depends on number of lots but known with more certainty than the food bowl schemes.

Figure 3-6 provides an indicative picture of the potential of these recycling schemes over time. However, it needs to be noted that each scheme is at varying phases of development and only ‘current’ and ‘approved’ schemes are committed. Further, actual recycling volumes are dependent on climatic conditions and customer uptake. In terms of the schemes that are at ‘Feasibility’ and ‘Concept’ stage, Melbourne Water and SE Water will work with key stakeholders in undertaking further investigations. Any decision to proceed to implementation will be dependent on the merits of the business cases.


Potential Development of Recycling Flow Diversions Through Small-Medium Scale Schemes in South East

0

5

10

15

20

25

30

35

40

45

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Year

GL

per y

ear

Early concept - foodbowl development e.g. Casey-Cardinia

Early concept - new Casey area third pipe

Feasibility

Approved

Current Schemes

Figure 3-6: Potential Development of Recycling Flow Diversions through Small-Medium Scale Schemes in South East

The quality of recycled water required for each recycling scheme depends on the particular application and what controls apply at the point of use, and the likelihood of people coming into contact with the water or using it inadvertently. All of the schemes as described in Table 3-2, Table 3-3, and Table 3-4 would require

higher quality water than is currently produced by the secondary treatment process at ETP, and tertiary or advanced tertiary treatment would provide water of suitable quality for these applications, as discussed in Section 4. The overall picture in Sections 3.3 to 3.6 is hence one of declining flows and loads to the environment. Successful adaptation to the uncertainties of climate change, and the drivers for increased utilisation of fit for purpose water resources where practicable, will continue this trend. The local recycling developments as discussed above have the potential to significantly enhance this, taking up to one third of the total flow. In the future, other possible uses for the water resource, including larger scale recycling schemes, may become favourable. Expectations from particular sections of the community and local interest groups around ‘closure’ of the outfall are unlikely to be achieved in the short to medium

108 Melbourne Water

term, and continued discharge of the treated water in excess of recycling demands will be required. Larger scale recycling projects have the potential to take the balance of flows, particularly in dry weather, but are major commitments of the community’s resources. Implementation of such projects should be timed to consider the overall water resources outlook and the social, economic, and environmental constraints applying at the time. This can be done as part of regular reviews of the Metropolitan Water Supply Demand Strategy and Central Region Sustainable Water Strategy where updated consideration of potential sources and uses of water in a strategic and integrated manner takes place.

3.7 Policy and Regulatory Aspects

3.7.1 Our Water Our Future

The 2004 White paper “Securing our Water Future Together” included arrange of policy guidance and initiatives to ensure a long term sustainable water management approach for Victoria. Relevant aspects include - Increasing the use of alternative water supplies such as recycled water can have numerous benefits including improving the reliability of our water supplies, freeing up water for the environment or growth and reducing the amount of treated effluent discharged into our rivers bays and oceans. The Policy states - “In our urban communities we will use water that is fit for purpose- many uses do not require drinking water standards. We will use alternative water supplies for non-drinking purposes where there is a net benefit to the urban community and to minimise detrimental discharges to the environment” Reducing ocean outfalls is discussed – “…all water authorities must have programs to assess the impact of discharges on the environment and manage environmental impacts.”, and “Further, the Government and Water Authorities are working to reduce discharges from other ocean outfalls through water conservation and recycling initiatives.” The Policy states – “To protect the amenity and health of the marine environment, water authorities will continue to improve the quality and reduce the quantity of effluent discharged from ocean outfalls”.


“EPA Victoria will continue to work with industry and coastal water authorities to reduce pollutant loads and concentrations……to progressively reduce discharge impacts.” In June 2007 “Our Water Our Future – The Next Stage of the Governments Water Plan” was released, and focussed on providing water resources security for a growing population in the face of the climate change challenge. Diversification of potential water resources and enabling a flexible response to changing future needs were key approaches. Included in the plan were – “Recycled water provides a secure, rainfall independent supply of water that is fit for a wide range of uses. It must be made available as part of a strategy to diversify supplies, and a strategy to improve environmental health”, and “The Government is committed to upgrading the ETP to tertiary standard, a level where a wide variety of reuse is possible. The Upgrade of the ETP will be completed during 2012”, and “There will be complex technical trials of different treatment methods in 2008, which will inform a decision on which method to implement in 2009. The full program to upgrade the ETP will then commence.”

3.7.2 Statement of Obligations

The Melbourne Water ‘Statement of Obligations’ (SoO) under the Water Industry Act 1994 commenced on 1 July 2007 and was updated in October 2008. In performing its functions and providing its services Melbourne Water must: • manage water resources in a sustainable manner; and • effectively integrate economic, environmental and social objectives into its

business operations; and • minimise the impacts of its activities on the environment; and • manage risk to protect public safety, quality and security of supply; and • operate as efficiently as possible consistent with sound commercial practice; and • manage its business operations to maintain the long-term financial viability of the

Authority; and • undertake continuous review, innovation and improvement; and • collaborate with other public authorities and government agencies to take account

of regional needs. The SoO also requires Melbourne Water in performing its functions to apply the

110 Melbourne Water

Sustainable Management Principles, including the need to integrate both long-term and short-term economic, environmental, social and equitable considerations. In applying the Sustainable Management Principles Melbourne Water must develop and implement programs for assessing, monitoring and continuously improving the it’s sustainability performance, including: • responding to climate change • maintaining and restoring natural assets • using resources more efficiently, and • managing everyday environmental impacts

3.7.3 State Environment Protection Policy (Waters of Victoria)

The State Environment Protection Policy (SEPP) is a statutory policy that expresses in law the Victorian community’s expectations, needs and priorities for protecting and sustainably using the environment and the social and economic values that depend on it. The SEPP provides a means under which the requirements of the Environment Protection Act 1970 can be implemented and measured. A SEPP is intended to offer flexibility in approach and how actions will be implemented to achieve the environmental outcomes specified in the SEPP. Consequently, government agencies, businesses and communities have the opportunity to choose actions which are both affordable and which satisfy the requirements of the SEPP in the most cost effective manner. The SEPP was in draft format when the original works approval for the ETP upgrade was issued. Since that time the document has been finalised and was re-issued in June 2003. When implementing the SEPP there is a need to consider the size of the environmental impact and assess any environmental rehabilitation within the context of social and economic needs and priorities, so that the best overall outcome is achieved for the community. The following principles form the basis of the Policy applicable to ETP and should be used to guide decisions about the protection and management of Victoria’s surface waters. 1) Principle of integration of economic, social and environmental considerations.


a) Sound environmental practices and procedures should be adopted as a basis for ecologically sustainable development for the benefit of all human beings and the environment.

b) This requires the effective integration of economic, social and environmental considerations in decision-making processes with the need to improve community well-being and the benefit of future generations.

c) The measures adopted should be cost-effective and in proportion to the significance of the environmental problems being addressed.

2) The precautionary principle

(a) If there are threats of serious or irreversible environmental damage, lack of full scientific certainty should not be used as a reason for postponing measures to prevent environmental degradation.

(b) Decision making should be guided by: (i) a careful evaluation to avoid serious or irreversible damage to the

environment wherever practicable; and (ii) an assessment of the risk-weighted consequences of various options.

3) Principle of intergenerational equity. The present generation should ensure that

the health, diversity and productivity of the environment is maintained or enhanced for the benefit of future generations.

4) Principle of conservation of biological diversity and ecological integrity. The conservation of biological diversity and ecological integrity should be a fundamental consideration in decision making.

The SEPP classifies the receiving water body for the treated effluent in terms of segments and beneficial uses to be protected within a given segment. It describes the coast on which the effluent is discharged to as the ‘Open Coast’ segment and includes surface waters lying within 3 nautical miles of Victoria’s territorial baseline. The segment is described as ‘near pristine’ and requires the highest level of ecosystem protection. Beneficial uses do not permit a use of water or activity, but they identify the uses or values that depend on water quality. A beneficial use requires water of a certain quality and quantity for its protection. In the case of the open coast segment (considered to be a largely unmodified ecosystem) into which treated effluent from ETP is discharged, the beneficial uses to be protected include: • Aquatic ecosystems • Primary & Secondary contact Recreation • Aesthetic Enjoyment

112 Melbourne Water

• Indigenous and Non Indigenous Cultural and Spiritual Values • Aquaculture • Fish, Crustacea and Molluscs for human consumption Other relevant components of the SEPP (WOV) include the requirements for mixing zones and location of the discharge point. Mixing zones are areas where beneficial uses are not protected. Mixing zones will not be permitted if the resulting outcome is: • Environmental risks to beneficial uses outside the mixing zone • Harm to humans, unacceptable impacts on plants and animals or where it will

cause a loss of aesthetic enjoyment or an objectionable odour. Application of best practice measures and a continuous improvement focus are expected to in time, reduce the mixing zone and where practicable eliminate it completely. Practicability is an established workable principle that is utilised throughout the SEPP and other statutory tools under the Environment Protection Act 1970 and in other statutory regimes. Actions outlined in the SEPP should be carried out in a practicable manner and on a priority driven basis. When assessing the practicability of an action, the following issues need to be considered: • The severity of the environmental risk in question and the environmental benefits

of removing or mitigating that risk • The state of knowledge of the environmental risk and options for removing or

mitigating that risk • The availability, efficiency and suitability of options to remove or mitigate that risk,

and • The financial and social costs and benefits of removing or mitigating that risk. Practicability needs to be taken into account when making planning and management decisions, and particularly when undertaking actions to implement the SEPP. Environmental rehabilitation needs to be undertaken within the context of social and economic considerations and needs and priorities, so that the best overall outcome is achieved for the community. This is important as it ensures the environmental benefits justify the social and financial costs that may be incurred as a result of implementing environment improvement measures. Practicable actions are not necessarily the lowest financial cost options, but are generally considered to be what is ‘affordable’ in the context of the relevant industry or social sector.


How the various clauses of the SEPP relevant to ETP fit with the treatment and outfall scenarios available to Melbourne Water, have been assessed using a triple bottom line assessment. Further detail of this is discussed in Section 6.

3.7.4 ETP EPA Victoria Discharge Licence EM 35642

The EPA licence for ETP applies to the treatment and discharge of secondary effluent to the water of Bass Strait at Boags Rocks. The licence objectives include meeting the provisions of both the relevant SEPP’s and the Environment Protection Act 1970 for the ETP site operations and discharge to the environment. In addition to invoking the relevant legislation, the objective of the licence is to: • Ensure operations are in accordance with good environmental practice at all times • Ensure opportunities are taken to minimise waste and continuously improve

environmental performance, and • Maximise the reuse of treated effluent and sludge. The discharge to the marine environment must consist only of treated wastewater and the waste discharged must not cause the waters of Bass Strait, including the mixing zones and land in the vicinity of the discharge point to exhibit visible oil, grease, litter, foam or other objectionable material, or generate odours offensive to the senses of human beings.

3.7.5 ANZECC Guidelines for Fresh and Marine Water Quality

The main objective of the Australian and New Zealand Guidelines for Fresh and Marine Water Quality is to provide an authoritative guide for setting water quality objectives required to sustain current, or likely future, environmental values [uses] for natural and semi-natural water resources in Australia and New Zealand. The ANZECC Guidelines have been prepared as part of Australia’s National Water Quality Management Strategy (NWQMS). They provide government and the general community (particularly catchment/water managers, regulators, industry, consultants and community groups) with a sound set of tools for assessing and managing ambient water quality in natural and semi-natural water resources. The ANZECC guidelines provide a basis for environmental quality objectives, but are not mandatory, nor should they be regarded as such. The SEPP (Waters of Victoria) refers to the ANZECC guidelines, particularly when discussing and setting the objectives for the protection of beneficial uses in the given

114 Melbourne Water

segments. Unless specific objectives are described in the SEPP, the values derived from the ANZECC guidelines become the default objectives for the SEPP. Similar to the SEPP (Waters of Victoria), which looks to protect beneficial uses, the aim of the ANZECC guidelines is to protect environmental values through management goals that focus on issues (concerns or potential problems) rather than concentrations of specific parameters. The water quality concern or problem (e.g. toxicity, algal blooms, decrease in dissolved oxygen, etc) should be identified, so that the environmental processes that contribute to it can be examined. The environmental values for protection specific to the marine environment as defined in the ANZECC guidelines include: • aquatic ecosystems, • primary industries (including aquaculture and human consumers of aquatic foods), • recreation and aesthetics, • cultural and spiritual values (no water quality guidelines are provided for this

environmental value although cultural and spiritual values can be taken into account through the process of establishing the specific water quality objectives for a particular water resource).

Continual improvement is a fundamental principle guiding water quality management as part of the guidelines. The ANZECC guidelines also provide a framework for the implementation of adaptive management and monitoring programs for monitoring and assessing the extent of biological recovery after an environmental impact has occurred. Melbourne Water has used these principles to determine the most suitable monitoring programs for assessing changes in the receiving environment at Boags Rocks.

3.7.6 Recycled Water Quality Requirements

Recycled water risk management is based on a combination of suitable levels of recycled water treatment and site management controls. Lower levels of treatment require more stringent site controls, such as excluding human contact with the water, while higher levels of treatment mean reduced site control requirements and potentially no barriers between the water and human contact, thus enabling a broader range of uses. Many changes have been made to the requirements for achieving ‘Class A’ water since 2001. Class A is a term that has been used to describe the highest quality of recycled water such that it is suitable for a wide range of non potable applications, including such activities as fire-fighting, dual reticulation (which includes uses such as


clothes washing, toilet flushing, garden irrigation, car washing), municipal irrigation, and the irrigation of salad crops eaten raw. Evolution of the requirements for producing high quality recycled water has come from greater understanding of the risks and likely applications of recycled water. Australia is now leading the world when it comes to producing water with very low risk to health suitable for any given use. The guidelines ‘Guidelines for Wastewater Reuse (EPA Victoria, 1996, Publication 464)’ were updated in 2002 (Environmental Guidelines for the Use of Reclaimed Water (EPA Victoria, 2002, Publication 464)) which outlined the beneficial uses of the various Classes of water depending on the levels of bacteria, protozoa, virus and helminths present in the treated water together with the physical/ chemical properties that the water had to meet. This is similar to the approach taken in California with the Title 22 regulations which specify a treatment regime to be followed and a target of 2.2 total coliform bacteria/ 100mL over a given period of time. The focus of these type of guidelines is on the absolute numbers of pathogens in the treated water, and by achieving these low numbers of pathogens, ensuring the protection of public health. The next evolution of the Class A requirements came in 2003 GEM: Use of Reclaimed Water Class A Reclaimed Water Supply To Residential Properties: The Management Framework, which also defined ‘Class A’ based on numerical targets of pathogens in the treated water. This document and the pathogen targets contained within them were consistent with the EPA Guidelines released in 2002. In late 2005 EPA Victoria published the ‘Guidelines for Environmental Management: Dual Pipe Recycling’, which took a quantitative microbial risk assessment approach to pathogen reduction for this particular application for recycled water. Quantitative microbial risk assessment (QMRA) is a robust methodology for establishing water quality guidelines. QMRA uses quantitative data to mathematically assess consumer exposure to pathogens and the resulting health risk. It includes four steps: hazard identification; dose response determination; exposure assessment; and risk characterisation. Using a defined ‘tolerable risk’ a QMRA model can be used to determine the concentration at which a specific pathogen can be present in water such that the risk to the community using that water will not exceed the defined tolerable risk level.

116 Melbourne Water

Quantitative risk assessment techniques are described as being several orders of magnitude more sensitive than epidemiology. The dual pipe guidelines included targets of 7 log reduction of virus and 6 log reduction of protozoa from raw sewage to final effluent, using a conservative approach of taking the most resistant pathogen to each process unit and then summing up the log reductions across the treatment train. These guidelines offered no flexibility for the use of site specific pathogen data, which may have indicated that these log reductions were either overly conservative or not conservative enough to protect the user depending on the pathogen concentrations in the raw sewage. In November 2006, the Australian Guidelines for Recycled Water: Managing Health and Environmental Risks were released. This document also takes a risk based approach to producing a ‘fit for purpose’ recycled water, however it allows for a site based risk assessment using site specific pathogen data. These guidelines do not specify ‘Classes’ of water rather they require a risk assessment to be undertaken depending on the final end use of the recycled water and whether it is possible to provide controls to prevent access to the recycled water or if all of the controls need to be done via treatment. An example of this is for dual pipe recycled water applications where all of the risk prevention needs to be undertaken via treatment as there is no formal way of controlling access to the water and potential inadvertent uses. However if the water is to be used for irrigation of a golf course, it may be possible to irrigate at night when there is minimal risk of people coming into contact with the recycled water as an additional barrier to providing a given level of treatment. This approach allows for ‘fit for purpose’ recycled water to be produced which enables costs to be optimised (in terms of not over-designing plant and using the most effective control barriers to protect public health), yet still providing a safe recycled water product. Key aspects of a risk assessment under the AGWR include the following: • Identification and enumeration (where possible) of the microbial hazards in

wastewater (primarily bacteria, viruses and protozoa) • Consideration of the possible uses of recycled water, including the exposure risk

associated with the respective end uses


• Calculation of the log reduction values for the respective target pathogens to achieve the relevant “tolerable risk” of 10-6 DALYs per person per year for all pathogens.

All recycled water schemes require DHS endorsement of the proposed treatment plant commissioning and water quality verification prior to submission of a scheme’s Environment Improvement Plan (EIP) to EPA Victoria for sign-off. Melbourne Water has been working with the DHS through the tertiary technology trialling phase at ETP and will continue to do so through any subsequent design phases to ensure the relevant recycled water requirements are met. Application of the Australian Guidelines for Water Recycling approach to derivation of treatment targets indicates the most sensitive use for the recycled water is fire-fighting. It is proposed that the recycled water produced from ETP be suitable for this application, thus allowing for safe use in all other less sensitive applications. Other concepts that have evolved over the years with regard to the production of fit for purpose recycled water include: • The use of a multiple barrier concept- using more than one treatment technology

or barrier to address pathogen reduction • Treating the water to a very high microbiological standard means by default the

physical and chemical properties of the water will be very good. For any recycled water produced for a high value end use, the overriding water quality objective will be pathogen reduction.

• Previous ‘Class A’ requirements that specified turbidity, suspended solids and BOD levels were generally included to ensure that the water was treated to a level that would allow adequate disinfection to occur.

• The use of the DALY (Disability Adjusted Life Year) concept, which weights a health impact in terms of severity within the range of 0 for good health to 1 for death. It takes into consideration the duration and severity of disability, which in this context is generally illness. The approach is to protect quality of health such that there is an annual diarrhoea risk of 1 illness per 1000 people. (Currently the reported rate of diarrhoeal illness in Australia is 0.8-0.92 cases per person/year).

As the pathogen reduction requirements have evolved over the years, so have the treatment requirements. Similarly treatment technologies such as membrane filtration and UV disinfection have further developed, with suppliers having greater understanding of the suitability and limitations on the technology. The regulatory changes, together with information from the technology trials and new USEPA guidance material on the required UV disinfection doses for certain pathogens,

118 Melbourne Water

have altered the cost-benefit balance of the preferred treatment approach from that envisaged in 2001. Regulatory interpretation of recycled water guidelines will continue to evolve as a greater understanding of the risks to human health from the various recycled water uses develops. Australia is leading the world in this aspect and it will be important to continue to monitor developments and have flexibility to meet future regulatory requirements.

3.7.7 Melbourne Water’s Strategic Framework

Melbourne Water’s recently updated Strategic Framework formalises Melbourne Water’s long-term vision of ‘working together to ensure a sustainable water future’. It spells out the organisation’s commitment to sustainability and has been developed in consultation with stakeholders including EPA Victoria, Department of Sustainability and Environment, Department of Human Services, Department of Treasury and Finance, Sustainability Victoria and the Metropolitan Water Retailers. The Strategic Framework underpins Melbourne Water’s Water Plan regulatory submissions and Corporate Plan preparation, as well as strategies, policies and procedures that Melbourne Water uses to guide its activities. It provides the context for Melbourne Water’s planning process, ensuring that social, environmental and economic impacts are considered in all aspects of our business operations. The relevant portions from the Strategic Framework which would have bearing on options assessment for this project are as follows: Intents -

• Manage water resources sustainably and secure supplies for a range of uses in the context of population growth and climate change

• Protect public health by providing safe water, sewerage and drainage services • Protect, conserve and improve natural assets and use natural resources

sustainably • Be recognised as a reliable and trustworthy organisation, willing to listen, work

collaboratively and deliver on our promises Goals -

• Secure water supplies for current and future generations by developing new, alternative and diverse water resources

• Deliver safe sewage transfer, treatment and disposal


• Supply fit for purpose and reliable recycled water • Improve environmental outcomes from all aspects of the business • Improve the health and amenity of waterways and marine environments • Minimise waste disposal and maximise resource efficiency • Invest prudently and efficiently, taking account of environmental, social and

financial considerations, whole of life costs, risks and service needs • Preserve and promote cultural heritage • Listen to and engage the community to seek support for our projects and

priorities Success Indicators -

• Effluent from sewage treatment plants is recycled or put to beneficial use • Drinking and recycled water quality meet or exceed regulatory and customer

standards • Sewerage services meet or exceed EPA Victoria licence requirements and do not

pose community health risks • Treatment plant and other wastes are converted into valuable resources • Cultural heritage values are acknowledged and preserved • Customers and the community receive value for money

Other key Melbourne Water policies include the Public Health and Environment policies. The Environment policy requires 100% compliance with statutory and agreed environmental requirements. The Public Health policy requires that Melbourne Water ‘transfer and treat sewage and ensure appropriate disposal, recycling or beneficial use of water and biosolids in a way that safeguards the health of the community’

3.8 Community Expectations

The community has been extensively engaged on issues surrounding the Eastern Treatment Plant and it’s environmental impacts and benefits over many years, including throughout the course of the CSIRO Effluent Management Study, in the shaping of Melbourne Water’s original Works Approval submission and over the course of the 2002-03 Works Approval process. Community groups such as Clean Ocean Foundation have shown an active interest in the Boags Rocks outfall with an ultimate goal being the ‘closure’ of the outfall The Tertiary Technology Trials plant has generated significant interest throughout the Water Industry, both locally and internationally as an example of best practice to

120 Melbourne Water

understand the capabilities of the various technologies suitable for tertiary treatment at ETP. Melbourne Water has engaged with the Eastern Treatment Plant Community Liaison Committee (ETP CLC) regularly on this topic over the past 18 months, with presentations on the trials plant, tours through the facility, demonstrating the various water qualities possible through treatment and most recently a presentation on the proposed way forward for the upgrade of ETP. The community and the water sector specifically has a greater understanding and awareness of emerging contaminants such as endocrine disruptors, pharmaceuticals, personal care products and other micro-contaminants, including the value of additional barriers to address residual risks where more sensitive uses of recycled water may develop over time.

3.8.1 Community Consultation

ETP and the Boags Rocks outfall has been a point of community interest for many years, mainly driven by the surfriders and local residents of the Gunnamatta and St Andrews communities. There have been several major phases of community engagement and stakeholder consultation associated with the broader assessment of the impacts at Boags Rocks and consideration of improvement options, including: • CSIRO Effluent Management Study Consultation process • Community Consultation to help shape Melbourne Water’s original submission to

the 2002-03 Works Approval process, including the use of focus groups • As part of the formal EPA Victoria works approval assessment process • Ongoing engagement with an active ETP CLC with representatives from a wide

range of community groups, with diverse interests and backgrounds. A four-person independent review panel was established to verify Melbourne Water’s community consultation program as part of its original Works Approval application to EPA Victoria. The panel concluded that Melbourne Water had ‘engaged in an extensive and appropriate consultation process for the proposed improvements to the Eastern Treatment Plant’ and ‘performed well on virtually all indicators’. One of the key themes that emerged from community submissions to the consultation process was that action to reduce the impacts of the Boags Rocks outfall should be for the long term and that “quick-fix” solutions were a waste of valuable funds and


limited budgets. This long-term perspective resulted in a strong view that only sustainable options for the next and future generations should be considered. This theme was illustrated clearly in the attitude to an outfall extension, which was not viewed as a long-term solution. The submissions indicated more support for abolishing the outfall than extending it. A principal concern raised by the community was that discharging what they described as ‘semi-treated’ effluent to the marine environment was unsustainable. This was reflected in broad support for upgrading treatment, and the general consensus of the need to upgrade ETP to facilitate use of the water resource and not to extend the outfall. There was widespread concern about the impact of the effluent discharge on the environment around Boags Rocks, especially relating to discolouration, odour, foam fat balls, litter, and public health. Some submissions also expressed concern about the impact of fresh water. Among the other themes that emerged from the submissions were a clear understanding of the value of water, the importance of water conservation and its link with consumer behaviour. It was recognised that treating effluent to tertiary standard would increase the opportunities for water recycling, which was seen as the best way to reduce the discharge. A significant minority of submissions called for effluent quality to be improved to potable (drinking) standard. This was seen by some as the only way to solve the problem of the outfall, but community acceptance of recycled water (especially for drinking) was identified as an issue, with some submissions ruling out using recycled water for human consumption. Water recycling to reduce the discharge at Boags Rocks was supported. A range of views was offered, and many people made the connection between water recycling and conserving valuable drinking water. There was an overwhelming sense in the submissions that extending the outfall would not solve the problems at Boags Rocks, only move them further out to sea, and that this option was more of a “quick fix” than a long-term solution.

122 Melbourne Water

Several submissions mentioned the environmental damage that would be caused by constructing the outfall. Only four (of 133) felt that extending the outfall should be considered. The factors such as climate change and associated water resource impacts explored in this section that influence the strategic context for decision making are considered only likely to have reinforced these community views over recent years.

3.8.2 Recent Focus Groups for the Melbourne Metropolitan Sewerage Strategy

In addition to consultation directed at ETP, there have been recent focus groups run for Melbourne Water in conjunction with the preparation of the Melbourne Metropolitan Sewerage Strategy. Community views on the management of sewerage in Melbourne varied, in that the average Melbournian who took part in the focus groups did not really know or fully understand the sewerage system or where their sewage went. Those who had some knowledge of the sewerage system generally achieved this through general interest rather than from media. Most people in the focus groups did not want to harm the environment and were often unaware the impact that their choices of product use would have on the environment and they did not knowingly intend to harm the environment. When questioned about the value of using sewage as a resource initially the majority of participants were unaware of the resources that could be used but after some explanation become aware of the resources contained within the sewage including water, energy and nutrients, they began to see the potential of this resource. Most people thought that we are a wasteful society and we need to learn to value our resources, including water. Recycling the water to conserve potable water for drinking was seen as being very important and this view was reinforced at a recent ETP CLC meeting.

3.8.3 ETP CLC Recent Views

The ETP CLC is a diverse group representing a broad range of community interest groups. The CLC is made up of representatives from the following organisations: • Bangholme Rural Land Holders Association • Birds Australia


• Carrum Indigenous Nursery • City of Greater Dandenong • City of Kingston • Clean Ocean Foundation • Frankston City Council • Department of Sustainability and Environment • Department of Planning and Community Development • EPA Victoria • Edithvale- Seaford Community member • Friends of Edithvale-Seaford Wetlands • Gunnamatta Surf Life Saving Club • Mornington Peninsula Shire Council • Paterson Lakes/ Carrum Village Committee • South East Water • Southern Peninsula Indigenous Flora & Fauna Association • Surfrider Foundation • Westernport Port Phillip Coastal Watch Association • Yarra Valley Water A series of presentations over the past 18 months have been given to the CLC to keep them informed of progress on both the tertiary technology trials and the path to the decision as to the preferred upgrade option for ETP. The initial presentation occurred in late 2007 which outlined the process that Melbourne Water was following to be able to make an informed decision as to it’s preferred treatment train for the upgrade of ETP. The CLC then toured through the trials plant in mid 2008 and was followed up with a presentation in February 2009 that summarised the work and findings from the tertiary technology trials. It provided details as to how these results would impact on treated water quality and the receiving environment, and the implications for Melbourne Water’s preferred technology choice for the upgrade of ETP. The committee was very supportive and excited about the work that Melbourne Water has undertaken and the proposed path forward for the ETP tertiary upgrade project. They see the value in upgrading the treatment plant to produce a high quality of recycled water that can be used for a broader range of applications. There were questions asked to ensure that Melbourne Water was considering the future and how the water resource from ETP may be integrated into a broader water resources strategy for Melbourne in the future.

124 Melbourne Water

The views from the CLC, received in February 2009, reinforce those views that were obtained from the community in 2001, and if anything reinforce the desire to see a standard of treatment that contributes to a portfolio of diverse, fit-for-purpose water resources. The desire to pursue increased utilisation of the treated effluent as a resource, and decrease discharge to the environment was clear, and has been a consistent theme from these community representatives.

3.8.4 Community Values around Boags Rocks

Boags Rocks is about 70 kilometres south of Melbourne, on the edge of the Mornington Peninsula National Park. The local area surrounding Boags Rocks is renowned for its environmental values, including ‘The Cups’ which is the eastern section of the Nepean Peninsula Sand Dune system and is of community and scientific interest because of its unusual topography, making it a unique area in Victoria. The beach area around the outfall is part of the Mornington Peninsula National Park and is used recreationally by surfers, swimmers, horse riders, fishing enthusiasts and those using the area for passive recreation such as walking on the beach and enjoying the environment. It is estimated that approximately 250,000 to 300,000 people visit the area each year. There has been a considerable amount of residential and golf course development in the nearby area of Cape Schanck and St Andrews in recent years. The area surrounding Boags Rocks forms part of a 35km continuous stretch of beach that runs from Cape Schank to Portsea. It’s a popular surf location with many good breaks that attract surfers all year round. Gunnamatta Beach is about 3km long and adjacent to the Boags Rocks outfall. It is one of the most dangerous places for swimmers due to the reefs, rips and high surf but these features make it recognised as the best surf beach on the southern Mornington Peninsula. The good breaks are down the beach past the Surf Club, and up the beach at a place known as ‘pumping station’, which the Surf Life Saving Australia website claims is polluted due to the outfall. The wave height averages around 1.9m. Although previous desktop scientific assessments of Gunnamatta beach had indicated it poses no greater health risk to swimmers and surfers than other beaches not


impacted by an outfall, there continues to be complaints about ear, nose, throat, skin and gastrointestinal illness by the surfing community after using the area. Perceptions of health risks from using recreational facilities can have an impact on community health. If there is a perceived health risk, the community will not use the area and those with limited resources may be unable to travel to another beach. For those people who for whatever reason choose to use the beach, their perceptions may limit their enjoyment when using the beach.

3.8.5 Where to from here?

In light of this updated strategic context, and a more comprehensive understanding of the ecological, health, and aesthetic impacts of the near shore discharge of secondary effluent, it is now possible to analyse the options for improvement and develop a preferred strategy. This is consistent with Melbourne Water’s proposal in late 2006 to: • Continue with the ammonia reduction works in the secondary treatment area to

realise the immediate benefits to the environment from ammonia toxicity reduction • Design, construct and operate the tertiary technology trials facility over the course

of 2007 and 2008, allowing Melbourne Water to fully understand and quantify the benefits of advanced tertiary treatment.

• Analyse the results from the tertiary technology trials and the latest marine science, and propose in 2009 the preferred method of upgrading ETP

Sections 4 to 6 describe the improvement scenarios and the selection of the preferred strategy.

3.9 Key Conclusions

• There have been significant changes to the strategic environment and influences on decision making since the initial Works Approval for the ETP Upgrade. These include policy and regulatory interpretation applicable to the project, and within the broader environmental context.

• Melbourne Water has also undertaken a wide range of additional studies to better inform the decision making process, and there is now a clearer understanding of the interaction between ETP operations and the receiving environment, and the community expectations for sustainable water cycle management.

• Drought has been a feature of the past 12 years, with below average rainfall being recorded, water restrictions in place for much of Victoria, and reduced streamflows impacting on waterway diverters.

• Climate change is now an accepted concept amongst the scientific community. • Bushfires have burnt through large areas of Water Supply Catchment which may

126 Melbourne Water

change runoff patterns over both the short and long term. • In light of the observed reduction in inflows sustained in recent years, and the

potential for on-going changes and variability in our climatic conditions, it is prudent to move away from relying on one major source of supply, currently being surface water reservoir supplies dependent on rainfall, to a more diversified portfolio of water sources including those which have less dependency on rainfall conditions.

• This policy direction was incorporated in “Our Water Our Future – The Next Stage of the Governments Water Plan” focussing on providing water resources security for a growing population in the face of the climate change challenge.

• Flows into ETP are trending down, since the peak in the mid 1990’s. This is consistent with the declining per capita sewage generation rate in Melbourne.

• Inflows at ETP are currently at levels not seen since the 1980’s. The outlook for flows to treatment at ETP indicates no growth in the coming years. The overall picture is one of declining flows and loads to the environment, with ammonia and nitrogen declining more than 90 and 60% respectively since the mid 1990s.

• Successful adaptation to the uncertainties of climate change, and the drivers for increased utilisation of fit for purpose water resources where practicable, will continue this trend.

• Local recycling developments have the potential to significantly enhance this, taking up to one third of the total flow.

• Expectations from particular sections of the community and local interest groups around ‘closure’ of the outfall are unlikely to be achieved in the short to medium term, and continued discharge of the treated water in excess of recycling demands will be required.

• Larger scale recycling projects have the potential to take the balance of flows, particularly in dry weather, but are major commitments of the community’s resources. Implementation of such projects should be timed to consider the overall water resources outlook and the social, economic, and environmental constraints applying at the time. This can be done as part of regular reviews of the Metropolitan Water Supply Demand Strategy and Central Region Sustainable Water Strategy where updated consideration of potential sources and uses of water in a strategic and integrated manner takes place.

• A range of regulatory provisions and interpretations have evolved including an update to the State Environment Protection Policy (SEPP) Waters of Victoria in June 2003, the Melbourne Water Statement of Obligations under the Water Industry Act, and the approach to ensuring safe production and supply of recycled water.

• The pathogen reduction requirements for producing high quality recycled (previously known as ‘Class A’) water have changed from prescribing treatment approaches and performance indicators to taking a risk based approach to ensure safe . In support of this approach the ‘Australian Guidelines for Water Recycling, Managing Health & Environmental Risks’ were released in 2006 to provide a framework for assessing


recycled water schemes to provide fit for purpose recycled water. • ETP and the Boags Rocks outfall has been a point of community interest and concern

for many years, particularly amongst the local residents and surfriders who use the environment for recreation. There was widespread concern about the impact of the effluent discharge on the environment around Boags Rocks, especially relating to discolouration, odour, foam fat balls, litter, and public health.

• There has been a wide range of consultation undertaken with key themes emerging around making decisions for longer-term sustainable approaches. There has been little support for extending the outfall, and broad support for upgrading treatment, to facilitate use of the water resource and divert flows away from the marine environment.

128 Melbourne Water

Improving the treatment provided at ETP is one option for reducing the

current marine impacts, either alone or in combination with an outfall

extension. Higher levels of treatment also facilitate significant reductions in

the need for disposal and the development of a diversified portfolio of fit for

purpose water resources.

A 12 month Tertiary Technology Trial has been undertaken which investigated

the feasibility of implementing advanced tertiary treatment for ETP along with

a range of other candidate technologies for improving the quality of the

treated effluent. The results from the trials allow Melbourne Water to make

informed decisions as to the preferred method of upgrading the Eastern

Treatment Plant.

This section describes the treatment options available, development of the

preferred treatment approach, what is involved in implementation, its

impacts, costs, and benefits.

4.1 Treatment Objectives

The treated water quality requirements for the ETP Tertiary Upgrade Project are driven by a combination of requirements associated with addressing impacts of effluent discharge in the receiving marine environment, and producing fit-for-purpose high quality recycled water. The treatment objectives associated arise from the discussion in the previous sections of this report and may be summarised as follows: Discharge Plume Visibility - is believed to be the result of combination of the current secondary effluent characteristics including suspended solids concentration, surfactants and foam, and in particular soluble or ‘true’ colour. Colour Reduction - effluent colour impacts on both discharge plume visibility at the outfall discharge and customer acceptance of recycled water products. Filtration can

4. Improving Outcomes Through Treatment


address the contribution of particulate matter to effluent apparent colour but has no impact on true or dissolved colour. Additional forms of advanced treatment beyond standard tertiary treatment are required to reduce true colour. Solids Reduction - is required to reduce discharge plume visibility, the food source for the exotic spionid worm Bocardia probosidea and improve effluent quality to ensure effective disinfection process performance. Filtration is the most feasible means of achieving this treatment objective. Litter Removal - Any of the filtration processes considered suitable for ETP are expected to eliminate all visible debris from the treated effluent. Foam Reduction - Foam can have both a visual and odour aesthetic impact on the receiving marine environment at the discharge. Tertiary filtration is expected to remove all of the activated sludge plant related foam (GALO). There is a residual risk of some residual foam from other causes such as surfactants which may not be removed by tertiary filtration and some form of advanced treatment would be required to address this. Fat, Oil and Grease (Fat Ball) Reduction - tertiary filtration will reduce the formation and quantity of fat balls. Odour Reduction - removing foam is expected to also reduce the incidence of odour. The reduction in odour through tertiary filtration alone would depend on the contribution to odour from foam as it will not address the dissolved compounds in the effluent. Advanced tertiary can address the dissolved compounds and hence offers significant additional odour reduction potential. Ammonia Reduction - in addition to that achieved by the Ammonia Reduction Project, provides additional benefits to the receiving marine environment and facilitates more efficient free chlorine disinfection for the production of recycled water. Pathogen Reduction - through tertiary treatment offers benefits to the receiving environment through further reduction in public health risks associated with recreational use of the receiving waters, and is also the primary requirement for production of recycled water for applications where there are potentially no barriers between the water and direct human contact. The production of high quality fit-for-purpose recycled water at ETP needs to provide 4 to 6-log reduction of pathogens from raw sewage to final treated water, with the specific requirements determined by the particular pathogen and the intended end use of the treated water.

130 Melbourne Water

4.2 Treatment Process Concepts

4.2.1 Tertiary treatment train concepts

Conventional tertiary filtration and disinfection process trains are able to address certain aspects of the impact of discharge to the receiving environment and produce high quality fit-for-purpose recycled water. Moving from the existing ‘Class C’ secondary effluent quality to ‘Class A’, basically comprise some form of filtration to remove particulate material (suspended solids) and some pathogens, coupled with additional downstream disinfection processes. Conventional tertiary filtration will address receiving marine environment impacts associated with litter, fat balls, suspended solids, and activated sludge plant foam. However, it will not address the dissolved (or true) colour or odour and thereby does not address all aspects of plume visibility, aesthetic amenity, and recycled water customer preferences. Other dissolved components such as ammonia will also remain in the treated effluent from conventional tertiary filtration. The conventional tertiary filtration processes applicable at the large scale of ETP are either granular media filtration (GMF - dual media with anthracite and sand layers) or microporous membranes (known as microfiltration – MF, or ultrafiltration - UF). Each of these filtration processes can reduce suspended solids to the requisite levels, but they differ in pathogen removal performance in the order of GMF < MF < UF. This relative performance has a significant impact on the levels of pathogen reduction which must be provided by the other treatment processes in the complete train. Regardless of the specific filtration process employed, downstream treatment would comprise Ultraviolet (UV) and combined chlorine disinfection. While the ETP is currently being upgraded for improved ammonia reduction, some residual will remain in the effluent (typically 2-5 mg/l) and therefore chlorine would be in the form of chloramine (known as combined chlorine), as has historically been the case at ETP. Combined chlorine offers a persistent residual but is not as strong a disinfectant as free chlorine (which occurs in the absence of significant ammonia). This increases the reliance on the UV disinfection step to provide the balance of treatment to meet the total pathogen reduction targets in conjunction with the filtration and chloramination process steps. Considering the relative pathogen removal capabilities of the respective filtration processes, the respective UV systems would have different pathogen reduction loads (i.e. capacities) in the order of UVUF < UVMF < UVGMF.


The Tertiary Treatment process trains which were taken forward for trialling may be summarised as follows: • Dual-media GMF + UV Disinfection + Chlorine (Chloramination) • MF + UV Disinfection + Chlorine (Chloramination) • UF + UV Disinfection + Chlorine (Chloramination)

4.2.2 Advanced tertiary treatment train concepts

Advanced Treatment could be employed in conjunction with Tertiary treatment to address the residual aesthetic effluent quality parameters of colour and odour, and provide additional treated water quality benefits for both the receiving marine environment benefits and recycling applications. There are a range of advanced treatment processes available for use in tertiary treatment although not all are suitable for use at the scale of ETP. An options assessment has been undertaken to short-list the advanced treatment processes most suited to this particular wastewater application at ETP. The advanced treatment options that have been considered for ETP include: • Ozonation • Ozone-Biological Activated Carbon (BAC) • Enhanced Coagulation • Colour reduction by Chlorination • Chlorine/Granular Activated Carbon (GAC) • Magnetic Ion Exchange (MIEX) • Nanofiltration • Granular Activated Carbon (GAC) • Powdered Activated Carbon (PAC) Each of these options offers relative advantages and disadvantages and a review resulted in the selection of the Ozone-BAC process for inclusion in the Tertiary Technology Trials. Key factors influencing the selection of the Ozone-BAC process over the other technologies included: • A colour ‘destruction’ process with no waste stream (other than a small filter

backwash stream of the solids removed from the effluent, that is relatively simple to handle and treat) unlike coagulation, GAC, PAC, Nanofiltration and MIEX processes. Ozone oxidation can provide a high degree of dissolved (true) colour reduction When this effect is coupled with BAC media filtration to reduce the

132 Melbourne Water

contribution of particulate matter to colour a low colour treated water can be produced which approaches drinking water colour and turbidity levels.

• Provides significant pathogen removal, through a combination of kill/inactivation by ozone and physical removal by BAC filtration, which other technologies such as MIEX, GAC, and PAC are not able to offer.

• Does not require significant chemical transport, unlike chlorination and coagulation processes.

• Production of treated water with very low ammonia levels through nitrification in the BMF filters.

• High degree of effluent odour reduction through a combination of ozone oxidation and BAC biodegradation of odour contributing compounds.

• Provide an effective barrier for residual microcontaminants, endocrine disruptors, pharmaceuticals, personal care products, etc. Although this is not an immediate effluent quality requirement, it provides a good platform for future high-end reuse applications.

• Includes a filtration step, potentially improving overall treatment train efficiency and cost effectiveness

• Enables the use of alternative more efficient forms of downstream membrane filtration, UV, and chlorine disinfection processes, and increases their effectiveness.

While the Advanced treatment process could in theory be ‘plugged-in’ to one of the conventional tertiary process trains, a significant finding from the recent trials program was that, in addition to addressing those dissolved water quality parameters which conventional tertiary treatment alone does not, the Ozone-BAC also provides major contributions to all of the other treatment objectives. It offers the greatest overall benefits when designed and utilised in conjunction with dedicated process trains which take advantage of the synergies between individual process steps. Initial desktop studies suggested that Ozone-BAC treatment may benefit from some degree of pre-filtration so as to mitigate peak solids loads, and to make it more analogous to drinking water applications from where the majority of industry experience stems. In addition to dual media filtration (as for conventional tertiary), the additional high-rate filtration processes of coarse mono media and cloth media were considered as pre-filters for Ozone-BAC. The Advanced Tertiary Treatment process trains which were taken forward for trialling may be summarised as follows: • Dual-media GMF + Ozone-BAC + (UV Disinfection) + Chlorine • Mono-media GMF + Ozone-BAC + (UV Disinfection) + Chlorine • Cloth filter + Ozone-BAC + (UV Disinfection) + Chlorine


• Mono-media GMF + Ozone-BAC + UF + Chlorine • Cloth Filter + Ozone-BAC + UF + Chlorine • Ozone/BAC + UF + (UV Disinfection) + Chlorine The specific inclusion and duty of UV disinfection was uncertain in some circumstances as it depended on the overall pathogen reduction requirements and the degree of pathogen reduction provided by the other treatment steps in the process train. Chlorine disinfection could be in the form of either free chlorine or combined (monochloramine) chlorine disinfection depending on ammonia concentrations and the feasibility of breakpoint chlorination. As compared to the conventional tertiary membrane processes where secondary effluent is fed directly to the membrane, the level of pre-treatment provided by Ozone-BAC enables consideration of higher throughput rate and lower cost membrane products.

4.3 Tertiary Technology Trials

4.3.1 Overview

Design, construction and commissioning of the Tertiary Trials Plant (TTP) was completed over the course of 2007 and a formal 12 month Trials program commenced in February 2008. It is planned to operate the TTP beyond the initial 12 month Trials for the purpose of supporting detailed design development of the selected process train and operational optimisation. While desktop assessments of treatment options can be undertaken based on industry experience and professional judgement, each application is unique and experience developed elsewhere is not necessarily directly translatable to new applications. It follows that there is a real risk that desktop treatment designs could incur inefficient expenditure on an overly conservative design, or delays to retrofit an under designed plant, or include incorrect selection of process technologies. Considering the scale of the ETP Tertiary Upgrade project, these issues are very significant, and investigative work such as the Trials is the only way to adequately address such risks and develop a robust basis for decision-making processes.

134 Melbourne Water

The Trials have provided MWC with design/performance data and operational knowledge and experience of the various treatment processes, enabling the evaluation of synergies of achieving receiving marine environment requirements, addressing residual aesthetic issues (colour and odour), and producing high quality recycled water. A key requirement for the project was to maximise the opportunity to scale-up the Trials data for full-scale plant considerations. This meant that the scale and configuration of the respective pilot plants had to be carefully considered, including the following: • The membrane units were sized to be representative of commercially available full-

scale module, and were equipped with control systems to enable (semi)automatic continuous operation including routine cleaning regimes.

• The media filters were to be of sufficient diameter to eliminate wall effects that are often seen in pilot studies, and were equipped with level and filtration rate controls and automatic air and water wash systems.

• The ozone system was based on oxygen feed to produce ozone gas at 10wt% concentration, and had to be large enough to provide ozonated water across a range of doses at flows suitable for the downstream process units.

To meet these requirements each of the primary process trains was designed with a nominal average flow capacity of 100-150 kL/d. Taking into account the expected peak flow capacities, the total flow through the Trials Plant is approximately 2 ML/d. Although comprising numerous different process trains, this total scale is comparable to a wastewater treatment plant for a small country town. The initial design process identified that there were potentially up to eight basic process trains that required investigation and trialling and, with multiple unit processes available at the trials plant, these eight basic process trains could be configured in thirty eight different permutations. The formal 12 month Trials were conducted in accordance with an experimental programme which was designed to generate the information required to achieve confidence in project recommendations, and an associated sampling and analysis program. The Trials team worked with an expert peer reviewer (Ian Law, a Chemical Engineer with a Masters Degree in Public Health Engineering and an Adjunct Professor at the University of Queensland. Ian was, until March 2003, CH2M HILL’s Technology Director for South East Asia, Australia, and New Zealand, and has more than 25 years of experience in advanced wastewater treatment projects), to progressively assess


the results and findings and subsequently adapt the respective investigation programs accordingly. The ETP tertiary trials are amongst the most comprehensive pilot tests of their kind, and the approach may be considered world leading. Some 40,000 laboratory analyses have been undertaken to date, and extensive online monitoring has been included. A summary of the key findings from the Trials is provided in Sections 4.4 to 4.6.

4.4 Treatment investigation findings

4.4.1 Dual Media Filtration

Dual media filtration achieved good solids removal and was able to produce low treated water turbidity (<2 NTU under most conditions) which would meet the basic filtration-specific requirements for the project (physical removal of particulate matter, litter, and fat balls). However, the achievable solids loading rates and associated filter run times under peak solids loading conditions were lower than expected. Pre-ozonation (see later) was found to significantly improve solids loading rate and run time performance. Without feed water coagulation or pre-ozonation the direct pathogen reduction of this conventional filtration step was limited, and therefore the pathogen reduction requirements would be met primarily by downstream disinfection processes. As expected, removal of dissolved components (such as ammonia or colour) of the effluent was minimal.

4.4.2 Mono Media Filtration

The Mono Media Filter achieved good solids removal and filtered water turbidity of <2 NTU under most conditions. Due to the coarser media it offered higher hydraulic loading rates (and hence reduced filter area) relative to dual media, however elevated feed water solids loads were not sufficiently attenuated to justify it’s use as an effective pre-treatment step for downstream Ozone-BAC treatment. In addition, the achievable peak solids loading rates and associated filter run times were lower than expected.

4.4.3 Cloth Media Filtration

The performance of Cloth Media Filtration was found to be comparable to that of Mono Media Filtration in terms of good solids removal and filtered water turbidity of <2 NTU

136 Melbourne Water

under most conditions. However, it also did not perform well when required with elevated feed water solids loads leading to elevated filtered water solids (up to 10 NTU) and raised similar concerns as to its effectiveness for this particular application.

4.4.4 Membrane Filtration

Both microfiltration (MF) and ultrafiltration (UF) membrane systems were successfully trialled and found to be capable of producing very low filtered water turbidity (generally < 0.1 NTU and always <0.2 NTU) under all conditions. Satisfactory hydraulic performance, in terms of flux and recovery, could be achieved using fairly standard membrane cleaning regimes and without evidence of problematic irrecoverable fouling. The hydraulic performance of MF membrane filtration is slightly better than for UF, however the pathogen reduction capability (particularly virus) of UF was higher thereby leading to UF being the preferred membrane filtration technology. The ability to remove pathogens through filtration reduces the load on downstream disinfection processes. Only UF membrane filtration was trialled downstream of Ozone-BMF treatment. In this configuration it was found to achieve almost twice the throughput (measured as flux) of UF filtration of direct secondary effluent. This is due to the fact that the pre-treatment steps produce a far improved feed water quality for membrane filtration. In summary, the ETP secondary effluent is technically suitable for membrane treatment.

4.4.5 Ozone-BAC Treatment

The viability of ozone treatment is directly related to the ozone dose required to achieve the treatment objectives. The Trials demonstrated that these objectives could be met using a feasible ozone dose. The required ozone dose was generally driven by the colour reduction objectives, with the ability to meet the other treatment objectives being assessed based on the colour-based dose. The media filtration step employed downstream of ozone normally uses granular activated carbon media. Pre-treatment by ozone results in the formation of a fixed-film biomass on the activated carbon and therefore it is referred to as biological activated carbon (BAC). The use of activated carbon, which has a microporous structure and is able offer extensive sites for biomass development, originates from its use in drinking water applications.


An alternative to the granular activated carbon is anthracite filtration media, which does not have the same pore structure or surface adsorption properties. Anthracite was also trialled and was found to offer comparable treatment performance to activated carbon while potentially offering some advantages at full-scale. At this stage the functionality of both appears similar and a final choice would be made based on further detailed investigation and design optimisation work over the coming months. In recognition of this the generic term biological media filtration (BMF), which covers both activated carbon and anthracite media, is subsequently used instead of BAC. While some very minor differences in BMF behaviour could be observed when it was fed pre-filtered water, a key finding from the Trials was that Ozone-BMF did not require a pre-filtration step. This allows for a simpler process train and avoids inter-stage pumping. Ozone-BMF treatment was found to provide both colour reduction and UV transmittance (UVT) improvement by reducing the contribution of both soluble compounds and particulate matter in the water to these parameters. Low treated water colour could be produced with this process step, with a reduction from 90 to 15 Pt-Co on a median basis using readily achievable ozone doses. Peak colour levels of 140 could be reduced to around 20 using feasible ozone doses for full scale application. In addition, a substantial increase in UVT from 40% to more than 60% UVT was seen on a median basis, providing significant benefits to the effectiveness of any downstream UV disinfection process. Ozone is a widely used disinfectant in water and wastewater and was found to provide significant pathogen reduction across each of the protozoa, virus and bacteria pathogen groups. This finding is important as it reduces the pathogen reduction requirements for downstream disinfection processes. BMF solids removal and treated water turbidity performance was comparable to Dual Media filtration (typically around 1NTU and <2 NTU 95th percentile), which would meet the filtration-related treatment requirements for the project. 90+% removal of turbidity was demonstrated during stress testing with high feedwater solids concentrations. Higher solids loading rates and longer filter run times were achieved, relative to Dual Media Filtration. Considering that comparable media bed configurations and filtration rates were used, this improvement in filtration performance is expected to be due to ozone microflocculation effects. Ozone-BMF treatment was found to provide robust biological nitrification and to be capable of producing very low treated water ammonia concentrations (<0.5 mg/L

138 Melbourne Water

ammonia-N). While the Mono and Dual Media Filtrations processes were also found to provide some nitrification, the degree of nitrification observed across Ozone-BMF was several times greater primarily due to the high levels of oxygen addition associated with dosing ozone. The two charts below illustrate the ammonia removal across the Ozone-BMF process when tested with fluctuating feedwater ammonia. They indicate robust ammonia removal capacity of around 5 mg/L. Peak flow and loading tests (including spiking tests with additional ammonia) has confirmed this excellent performance, and additional work at the trials plant is being undertaken to further extend this range for incorporation into final designs.

Figure 4-1 Ammonia Concentration into and out of the Ozone-BMF process


Figure 4-2 Ammonia removal across Ozone–BMF as a function of feed concentration

The Ozone-BMF treatment process facilitates synergistic effects between individual steps within complete process trains, including the following: • The ozone dose required to achieve the colour reduction objectives also provides

the following benefits: - microflocculation of feed water particulate matter which improves the

filtration performance of downstream BMF filtration; - significant levels of dissolved oxygen facilitating nitrification by downstream

BMF filtration; and - significant improvement in UVT

• Benefits associated with BMF filtration include: - production of very low treated water ammonia which facilitates very effective

free chlorine disinfection instead of combined chlorine; - significant solids and fouling potential reduction enabling downstream

membrane filtration operation at very high throughputs.

4.4.6 UV Disinfection

All the filtration processes investigated produced treated waters with turbidities within the range suitable for UV disinfection. The filtration only pre-treatment approaches, however, do not alter the colour and associated UV absorbing properties of the effluent.

140 Melbourne Water

Ozone treatment of both pre-filtered and unfiltered secondary effluent demonstrated a significant increase in UV transmissivity (UVT) through oxidation of the soluble colour and UV absorbing compounds in the secondary effluent. Subsequent BMF filtration provided an incremental increase in UVT through removal of the majority of the contribution of particulate matter to UV absorbance. Ozone-BMF treatment is capable of increasing the median UVT from around 40% to more than 60%. This means that UV disinfection becomes significantly more efficient downstream of Ozone-BMF. For example, a 99.9% reduction of Cryptosporidium would require around 2.5 times more UV lamps when treating non-ozonated effluent.

4.4.7 Chlorine Disinfection

All of the treatment trains which have been investigated include chlorine disinfection as the final treatment step. Chlorine can either be employed as combined chlorine or free chlorine depending on the treated water ammonia levels associated with the various treatment trains. Combined chlorine (i.e. monochloramine) is formed when chlorine is added to water containing ammonia up to a 5:1 mass ratio of chlorine to ammonia. Although the secondary treatment area at ETP has been upgraded to reduce effluent ammonia levels by more than 85%, the secondary effluent will continue to have some residual ammonia present, typically 2-5 mg/L ammonia-N. The tertiary filtration methods which do not remove further ammonia will hence rely on combined chlorine rather than free chlorine. Free chlorine is formed when chlorine is added to water that is either free of ammonia, or sufficient chlorine is added to react with any ammonia present (i.e. breakpoint chlorination). Ozone-BMF has the capability to produce treated water with very low ammonia levels, with a median of <0.5 mg/L and 90th percentile <2 mg/L. This additional reliable ammonia reduction means that free chlorine disinfection is a feature of those process trains which include Ozone-BMF. There is potential for the secondary effluent ammonia concentration to occasionally increase as a result of extreme plant flows associated with wet weather events. The fixed growth nature of the BMF means it offers good control of ammonia under peak conditions. Were the nitrification capacity of Ozone-BMF exceeded under the most extreme conditions, some small amounts of ammonia might remain in the treated water, but this is expected to be rare. Overall, chlorination in association with the Advanced Tertiary Treatment options is expected to be in the form of free chlorine for


more than 98% of the time. In the remainder of the time, it would be switched to combined chlorine mode, as currently practised at ETP. Nitrite from incomplete nitrification reacts rapidly with free chlorine and influences the immediate chlorine demand and therefore nitrite levels require consideration, however residual nitrite from the activated sludge plant is already very low and completion of the Ammonia Reduction Project is expected to improve treatment robustness even further in this respect. The additional nitrification capacity provided by the Ozone-BMF provides a further control of this aspect.

4.4.8 Supplementary Investigations

While not required to achieve the immediate project objectives, a likely component of any future high end reuse scheme is reverse osmosis (RO) treatment and therefore this technology has been trialled downstream of the candidate process trains as part of a ‘future-proofing’ investigation. The currently industry standard for reverse osmosis pre-treatment is membrane filtration, either in the form of microfiltration (MF) or ultrafiltration (UF), for the purpose of reducing particulate solids loads in RO feed water. This is usually done essentially as part of the RO ‘package’ with the RO representing the bulk of the cost. The only treatment process trialled which is capable of significantly altering soluble effluent quality parameters is Ozone-BMF. Therefore RO was trialled as part of the following process trains to ascertain if Ozone-BMF treatment had any impact on RO performance: • Secondary effluent – UF membrane filtration – RO w/cartridge pre-filtration • Secondary effluent – Ozone-BMF - UF membrane filtration – RO w/cartridge pre-

filtration RO performance has been assessed based on: normalised differential pressure (measure of fouling of the feed spacer), specific flux (measure of membrane permeability), salt passage and normalised permeate flow (temperature corrected flow). Evidence to-date suggests no measurable difference in RO performance in either process configuration, although the cartridge filters have a much lower fouling rate with Ozone-BMF treated water. Subsequent investigation will look at RO performance without cartridge pre-filtration.

142 Melbourne Water

It is expected that RO treatment would benefit from Ozone-BMF treatment to reduce dissolved organic fouling potential (from materials responsible for secondary effluent colour), and therefore the proposed advanced tertiary treatment upgrade is considered to be a good platform for future high-end recycling applications.

4.5 Treatment outcomes

4.5.1 Colour and solids reduction

Conventional tertiary filtration can reduce solids down to very low levels of around 1 NTU for media filtration and <0.1 NTU for membrane filtration based on median performance. Solids removal reduces apparent colour by removing the contribution of particulate matter, but conventional tertiary treatment does not provide any reduction in dissolved colour (known as True Colour). Advanced tertiary treatment using Ozone-BMF has demonstrated the ability to reduce solids down to around a median of 1 NTU, and True Colour down to 15 Pt-Co. In comparison, the Australian Drinking Water Guidelines5 state that, based on aesthetic considerations, true colour in drinking water should not exceed 15 HU (which are equivalent to Pt-Co units), and turbidity should not exceed 5 NTU. Therefore, based on typical performance the solids levels and True Colour of the treated water produced by Advanced Tertiary Treatment would meet the upper bound of acceptable drinking water in Australia. The impact of the advanced tertiary treatment on secondary effluent of varying quality is graphically demonstrated in Figure 4-3 below, including descriptions of the respective samples. In Figure 4-3, the first sample on the left is a secondary effluent quality with a turbidity of <5 NTU and a True (dissolved) Colour of 110 Pt-Co (equivalent to the 85th percentile true colour levels in the current secondary effluent). The second sample from the left is a secondary effluent sample with a turbidity approximating the 95-99th percentile.

5 National Water Quality Management Strategy, Australian Drinking Water Guidelines 6, 2004, Australian

Government, National Health and Medical Research Council & Natural Resource Management Ministerial

Council


The third sample from left is Ozone-BMF treated water quality with a turbidity of <2 NTU turbidity and a True Colour of 15 Pt-Co. This is representative of the expected typical treated water quality from Advanced Tertiary Treatment. The two samples on the right are secondary effluent samples that were spiked with additional solids for the purpose of stress tests at the Trials Plant and are not representative of typical secondary effluent quality, but are able to be treated by Ozone-BMF to the level shown in the middle sample.

Ozone-BMF<2 NTU15 PtCo

2o Effluent<5 NTU

110 PtCo

2o Effluent20 NTU

110 PtCo

Spiked 2o Effluent50 NTU

110 PtCo

Spiked 2o Effluent140 NTU110 PtCo

Figure 4-3: Relative secondary effluent and Advanced Tertiary Treated water qualities

144 Melbourne Water

Figure 4-4: Represents an alternative view of three of the five samples presented above.

The ability of the filtration process to limit peaks in effluent solids which might otherwise contribute to sporadic plume visibility problems is graphically demonstrated below, where solids “stress testing” was performed at the trials plants. The blue line indicates the feed solids concentration, which was maintained at around 40 mg/L for some 50 hours. The filters were also operated at their peak hydraulic loading rate throughout and the resulting solids loading rate represented >99th percentile loading conditions. Despite this extreme stress test the BMF produces effluent suspended solids of <5 mg/L. Continuous monitoring of turbidity through these tests also confirmed more than 90% removal.

2o Effluent

50 NTU 110 PtCo

Ozone-BMF

<2 NTU

15 PtCo

2o Effluent

<5 NTU 110 PtCo


Feed and BMF Filtrate TSS concentration (Stress test 14 to 16 Jan 2009)

0

5

10

15

20

25

30

35

40

45

50

0 10 20 30 40 50 60

TSS

(mg/

L)

FWHT TSS (mg/L)

BMF 2 Filtrate TSS (mg/L)

BMF 7 Filtrate TSS (mg/L)

Figure 4-5: Solids removal during stress test (Hours of test run along x-axis).

4.5.2 Foam reduction

Tertiary filtration will remove all foam forming organisms originating from the activated sludge process, which are the principal contributor to the risk of any discharge related foam at Boags Rocks. The residual risk of foam formation from other causes such as traces of surfactants (both synthetic and biological in origin) which may not be removed by tertiary filtration was investigated by testing samples from the Trials for foam formation potential. The basis of the foaming test involves agitating samples to a consistent extent and monitoring both the resulting foam formed and the time taken for the foam to collapse. The summary results from this testing is presented in the chart below.

146 Melbourne Water

0%

2%

4%

6%

8%

10%

12%

14%

16%

Max. Foam Volume Collapse Time

Foam

ing

pote

ntia

l inc

reas

e re

lativ

e to

tap

wat

er Secondary Effluent

Membrane Filtered Water

Ozone/BMF Treated

Figure 4-6: Foaming potential relative to tap water

The Ozone-BMF treated samples demonstrated the lowest foaming potential of the effluent samples tested with results directly comparable to tap water. Both the maximum foam volume and collapse times of the Ozone-BMF treated water samples were practically the same as that of tap water. The relative foam risk associated with the various effluent qualities can be represented as follows - Advanced tertiary << tertiary < typical secondary << secondary affected by GALO

4.5.3 Odour reduction

Odour reduction by a number of the treatment processes being considered was investigated, including direct secondary effluent, media and membrane filtration, and Ozone-BMF treated water. Only Ozone-BMF demonstrated significant odour reduction and/or odour character improvement. Ozone-BMF significantly reduced measured odour potential levels by 60-70% on average. In addition to this effect, the hedonic tone (degree of ‘pleasantness’) and the odour character descriptors were also significantly improved. Descriptors such as sewage, sulphide, rotten, refuse which were commonly applied to the current secondary effluent were absent from testing of ozone-BMF treated water. In addition, considering that foam at Boags Rocks has been linked to odour, the foam reduction provided Ozone-BMF as discussed above also reduces the potential incidence of odour further to what was indicated by the Trials Plant testing (performed on samples without significant biological foam influence).


When all four odour aspects of potential odour unit level, odour hedonic tone and character, and foam contribution are combined, Ozone-BMF treatment is expected to provide a major reduction in risk of offensive odour.

4.5.4 Oil and Grease Reduction

Conventional tertiary treatment removes particulate oil and grease that may give rise to fatballs on the beach near the discharge point. In addition to this filtration effect, Advanced Tertiary Treatment employs oxidation and biodegradation to address the potential precursors to fatball formation. The peak oil and grease levels in the treated water, which are most likely to give rise to observable fat balls, are able to be reduced by at least 90% to less than 2mg/L which is below the level of detection for oil and grease analysis.

4.5.5 Toxicity

Previous whole effluent toxicity testing work (discussed in Section 2) identified ammonia as the major toxicant in the ETP effluent, e.g. ammonia accounted for all of the toxicity to scallop larvae in eight of the ten ETP effluent samples collected in 2005-07. Studies with ETP effluent have confirmed a decrease in effluent toxicity with improved nitrification and denitrification treatment processes to reduce ammonia concentrations in the effluent. The test species are chosen to represent the most sensitive aspects of the marine receiving environment and includes key indicators such as germination of macroalga (H. Banksii.). Various treated water samples representing the range of process trains included in the Trials were tested and analysed by CSIRO for toxicity in accordance with Melbourne Water’s historical and ongoing studies. The testing indicated that Ozone-BMF treated water generally demonstrated lower toxicity for the test species as compared to the other treated waters. The first round of testing indicated that Ozone-BMF treated water was of comparable low toxicity to microalgae and scallops as the other samples, and was not toxic to macroalgae where the other effluents were found to be of low toxicity. The second round of testing indicated that Ozone-BMF treated water was not toxic to all test species, whereas the other samples were found to be toxic to at least two of the three test species.

148 Melbourne Water

Ozone-BMF treatment has the capability to address some of the other potential minor toxic components of the ETP effluent, as well as the residual secondary effluent ammonia, and consequently it can be said that the Advanced Treatment trains which include Ozone-BMF treatment are expected to produce treated water with lower toxicity to the marine environment than that from conventional tertiary treatment alone. The most sensitive test species to ammonia is H. Banksii. and where ammonia is kept below 5 mg/L a safe effluent dilution of 20:1 is derived based in the ANZECC guidelines. Advanced tertiary will consistently keep ammonia levels below this (median <1 and 90th percentile <2) and hence a significant safety margin applies. The whole effluent toxicity testing using water from the Ozone -BMF process has been undertaken and the results have been used with the ANZECC guidelines to derive a safe dilution of 20:1. The use of the ANZECC guidelines to derive a safe dilution is considered a conservative approach.

4.5.6 Trace Metals Reduction

Trace metals associated with particulate material will be removed in proportion to the solids removal in filtration. For the advanced tertiary options, as well as the micro-flocculation provided by ozone, the oxidation effect means that it may convert some trace metals in the effluent to less soluble forms, offering greater potential for removal in the subsequent filtration step. The typically very low levels of some trace metals in the ETP effluent (often below routine measurement detection limits) make this difficult to demonstrate empirically without extended testing at the lowest available detection limits. Initial testing has indicated average removals for Aluminium, Copper, Iron, and Manganese across Ozone-BMF of 41%, 18%, 26%, and 29% respectively. There was also some evidence of increased removals when influent concentrations were greater, but extended testing would be needed to demonstrate this effect conclusively.

4.5.7 Emerging contaminants

Ozone-BMF has been found to provide an effective barrier to contaminants of emerging concern. The removals achieved by Ozone-BMF for pharmaceuticals, pesticides and herbicides, and fragrances are presented in the tables below.


Note that the levels of the respective compounds in the ETP are very low (typically part per trillion range) and are expected to be associated with domestic sewage (derived from dietary and household sources), as opposed to any specific trade waste discharges, and reflect the very low background levels associated with our environment and the foodstuffs we consume. Table 4-1: Ozone-BMF pharmaceutical reduction performance

Compound Description Feedwater concentration

Removal across Ozone-BMF

Carbamazepine Antieplileptic 1 ug/L > 99%

DEET Insect repellent 0.3 – 3.0 ug/L ~ 78%

Atorvastatin Lipid regulator 0.04 ug/L ~ 53%

Diclofenac Analgesic 0.4 – 0.6 ug/L > 98%

Erythromycin Antibiotic 0.05 – 0.3 ug/L ~ 95%

Iopromide Contrast media 0.2 – 0.6 ug/L ~ 70%

Sulphamethoxazole Antibiotic 0.2 – 0.45 ug/L > 98%

Trimethoprim Antibiotic 0.2 – 0.5 ug/L > 98%

Citalopram Antidepressant 0.1 – 0.2 ug/L > 95%

Fluoxetine Antidepressant 0.02 – 0.05 ug/L ~ 80% Table 4-2: Ozone/BMF pesticide and herbicide reduction

Compound Description Feedwater Concentration

Removal by Ozone/BMF

Diazinon OP insecticide 0.04 ug/L >99%

Metalochlor Herbicide 1 - 3 ug/L 70 – 85%

Simazine Herbicide 0.2 – 0.8 ug/L > 90%

Table 4-3: Ozone-BMF fragrance reduction performance

Compound Description Feedwater

Concentration

Removal across

Ozone-BMF

Galaxolide Polycyclic synthetic musk ~ 1400 ng/L > 95%

Tonalid Polycyclic synthetic musk ~ 300 ng/L 95 -99%

Musk Ketone Artificial nitro-musk 30 – 80 ng/L 90 – 95%

International experiences with the use of Ozone-BMF in drinking water production, and for sensitive wastewater recycling and discharge applications, support this evidence of an excellent broad spectrum barrier to microcontaminants. Such work has

150 Melbourne Water

also indicated an even broader range of compounds are successfully removed by Ozone-BMF, however other removal rates were unable to be calculated at ETP due to ‘non-detect’ results (not present or below detection limits).

4.6 Treatment Option Assessment and Short-listing

The Trials have shown that while conventional Dual Media Filtration would meet the basic filtration-specific requirements for the project (physical removal of particulate matter, litter, and fat balls), the pathogen reduction requirements would be met primarily by downstream disinfection processes when operated without significant feed water coagulation or pre-ozonation. The high colour in ETP effluent and associated low UVT, in combination with changed regulatory guidelines for recycled water and pathogen reduction via UV disinfection, reduces the feasibility of UV as a primary disinfectant (due to technical, power consumption, and cost considerations) unless the colour is first reduced by ozonation. These factors have eliminated the earlier cost advantage of the conventional Dual Media Filtration + UV + Combined Chlorine process train, and it does not provide the additional environmental benefits associated with removal of dissolved components (such as ammonia or colour) that advanced tertiary offers. Membrane filtration is a technically feasible technology for use on ETP effluent, with standard cleaning regimes proving suitable for addressing solids driven fouling issues. Of the membrane types, UF proved more suitable than MF due to the greater pathogen reduction, thus reducing reliance on downstream UV disinfection. Chlorine disinfection for these options would still be in the form of combined chlorine as ammonia will be present. The degree of pathogen reduction offered by combined chlorine in association with the conventional tertiary treatment options (i.e. those without the Ozone-BMF process incorporated) is limited for certain pathogen types. The most feasible conventional Tertiary Treatment option was found to be – UF Membrane Filtration + UV and Combined Chlorine Disinfection. As for dual media however, this does not offer the additional environmental benefits associated with removal of dissolved components that advanced tertiary offers. A key finding from the Trials was that Ozone-BMF Treatment did not require a pre-filtration step in order to provide the required water quality, and this significantly improved the simplicity and feasibility of the Advanced Tertiary Treatment options.


Rather than being an add-on to conventional tertiary the advanced instead becomes the foundation of the preferred treatment process to address marine impacts and produce recycled water. Pre-ozonation significantly improved the conventional media filtration performance and provided a significant pathogen barrier, as well as addressing colour, odour, foaming potential and facilitating further biological ammonia reduction. The Advanced Tertiary Treatment process trains take advantage of synergies between individual process steps whereas the conventional tertiary process trains do not. For example, Ozone-BMF treatment increases UVT and removes ammonia thereby reducing the size of downstream UV disinfection and enabling highly effective free chlorine disinfection. Ozone-BMF also has a major impact on the efficiency of membrane filtration when used downstream. The additional benefits for the marine environment offered by the Advanced Tertiary process trains were found to be significant. The additional ammonia reduction, and barrier to potential toxicants, and improvement to the key aesthetic parameters are attractive features, both for receiving waters and facilitating customer acceptance and uptake in recycled water applications. Based on these factors the short-listed options were: 1. Ozone-BMF + UF Membrane Filtration + Chlorine Disinfection 2. Ozone-BMF + UV and Chlorine Disinfection 3. Ozone-BMF + Chlorine Disinfection A high level comparison of these three treatment options is provided in Table 4-4 below. Each of these Advanced Tertiary Treatment process trains offer largely the same degree of benefits for the marine environment in terms of: • the basic filtration requirements to address – litter, solids/turbidity, foam forming

organisms and fat balls • ammonia and toxicity reduction • colour, odour, and residual foam forming potential The last option offers small potential capital and whole of life cost savings of 6.6% and 8.3% respectively, but offers insufficient pathogen barriers (particularly Cryptosporidum) to ensure accreditation for “Class A” recycling applications. It is hence less likely to facilitate diversion of product water from the marine environment to recycling applications.

152 Melbourne Water

The first option produces consistently high quality treated water quality, however the cost penalty of providing and maintaining the UF membrane filtration step is considerable. The second option provides the same benefits for the marine environment, and also produces a high quality recycled water product. It is expected to meet requirements for supply to the most sensitive “Class A” applications for at least 98% of the time (investigations are ongoing to extend this further). As with most recycling schemes (which typically don’t take supply during peak wet weather affected periods, or maintenance outages, etc.), any possible short-term restrictions on recycled water supply would be readily managed by utilising distribution system and on-site storages. This option presents worthwhile greenhouse (19%) and whole of life cost savings (21%) relative to the first option, and would be designed to enable later retrofit of a UF membrane filtration process step (as discussed in Appendix 5) if future recycled water customer or regulatory needs require it.


Ozone/BMF/UF/Chlorine

Ozone /BMF/UV/Chlorine

Ozone /BMF/Chlorine

Net Present Cost $M 427 339 311 Meets Class A recycled water requirements

Unlikely

Turbidity Reduction best performer for this Colour Reduction Foam Reduction Odour Reduction Addresses peak ammonia toxicity

Recreational water quality risk reduction

Less effective than other options

Greenhouse gas impacts Highest power user Intermediate power user Lowest power user Future proofing Provides a very high quality

water meeting Class A and addressing receiving

environment.

Lowest cost option for producing Class A and addressing receiving

environment. Can be retrofitted later with UF membranes to replace UV.

Can readily be upgraded in the future as required.

Certainty of outcomes under all flow and load conditions

Multiple barriers capable of meeting Class A requirements

even if some processes perform below expectation.

Multiple barriers. Some inter-dependence between process unit

performance. Designed to enable UF retrofit to adapt if regulatory or

customer requirement changes.

Less pathogen barriers. Less certainty on peak flow

recreational risk outcomes for protozoa.

Table 4-4: Comparison of short-listed process trains

154 Melbourne Water Eastern Treatment Plant Upgrade: Information in Support of a Works Approval Application

4.7 Description of Preferred Treatment Option

The lowest cost treatment train which is expected to meet the project objectives is Ozone-BMF Treatment with UV and Chlorine Disinfection. Considering that Ozone-BMF Treatment and Chlorine Disinfection are common core process steps, this process train could be readily augmented in future to include UF membrane filtration should it be required. The preferred Advanced Tertiary treatment process is outlined in Figure 4-7 below.

Figure 4-7: Preferred process train

This option is described in detail in the Concept Design Report prepared by Black & Veatch and KBR, included in this submission as Appendix 6. The works required, and resulting process train, are outlined below: Plant location: The Advanced Tertiary Treatment Plant (ATTP) would be located in the vacant area to the north and east of the existing anaerobic digesters to facilitate the key tie-ins with the Effluent Holding Basins (EHBs) and Outfall Pump Station (OPS). Tertiary supply pump station (TSPS): The ATTP is essentially being inserted within the existing gravity flow path from the EHBs to the OPS and the hydraulic grade between these two assets is only sufficient to facilitate that direct transfer by gravity. Therefore, a low lift pump station is required to lift secondary effluent by approximately 12 m into the ATTP and subsequently deliver treated water to the OPS by gravity flow through the ATTP process and treated water storage. The pump station will draw secondary effluent from the channel to the west of the OPS and would generally operate at a flow rate matched to the OPS, plus an allowance for filter backwash flows.

Biological Media Filter

Ozonation Chlorine Injection

Contact & storage

2o

Effluent ?

Ultraviolet disinfection

Biological Media Filter

Ozonation Chlorine Injection

Contact & storage

2o

Effluent ?

Ultraviolet disinfection


ATTP feed water management: Means will be provided to allow the ATTP to receive flows either from the EHBs (normal operation) or directly from the Secondary Effluent Channel to provide flexibility in terms of ATTP feed water source selection. This ability allows performance to be optimised through solids and ammonia load balancing. Strict separation of the advanced tertiary treated water and secondary effluent will be maintained. Ozone dosing: Ozone is required to provide a number of treatment functions as follows: • reduction of the aesthetic parameters colour, odour and foam • increases the UVT to enable more efficient downstream UV disinfection • pathogen reduction (i.e. disinfection) for protozoa, viruses and bacteria • oxygenation of the flow ahead of the Biological Media Filters (BMF) to support

biological treatment in that process • microflocculation of particulate matter to improve downstream BMF filtration

performance Ozone will be generated on-site from oxygen feed gas. The oxygen feed gas will be supplied from two sources. The baseline oxygen load will be supplied by an on-site oxygen generation plant. Additional oxygen demand in excess of the baseline load will be supplied by a liquid oxygen storage system. The discharge from the TSPS drives the secondary effluent through two parallel ozone contactor pipes. The ozone gas will be contacted with the main process flow using a side-stream injection configuration whereby ozone gas is injected into a side-stream using a venturi before it is reintroduced to the main flow. Any ozone-off-gas will be collected at the end of the ozone contactors and destructed to oxygen prior to discharge to the atmosphere. Biological media filters (BMF): The ozone contactors will discharge at the BMF plant. These are deep bed downflow granular media filters primarily comprising either granular activated carbon or anthracite media with a sand bed layer underneath. The filtration process removes particulate matter from the water. In addition, due to the prevailing process conditions, a biological population develops on the surface of the media and degrades various compounds in the water. In particular, the filters support nitrification resulting in reduced ammonia levels in the treated water. The filter block will produce a net design outflow of approximately 700 MLD to match the current maximum capacity of the OPS, requiring a filter inflow of around 735 MLD to provide sufficient filtered water for filter backwashing.


A maximum specific filtration rate of 12 m/hr has been used to size the 36 filters in the block with 2 filters unavailable due to backwashing and/or maintenance. Under typical average conditions the actual filter loading rate will be significantly lower at around 6 to 7 m/h. Media is expected to be approximately 1.7m of anthracite (1.3mm) or activated carbon, and 300mm of sand (0.6mm), but fine tuning details of the media type, sizing and depth will be resolved in subsequent design phases. Backwash water will be drawn from a clear-water tank at the filter outlet. Air scour will be included in the backwash cycle. UltraViolet disinfection: Filtered water from the BMF process will gravitate to a UV disinfection process, based on either open channel or closed reactor configurations which will provide further pathogen reduction, particularly protozoa (Cryptosporidum) and bacteria. The plant will include self-cleaning and automatic level control to maintain constant submergence. Chlorine disinfection: chlorine disinfection provides additional pathogen reduction, particularly virus and bacteria reduction, and a residual as appropriate for recycled water. The chlorine will be provided as solution from the existing ETP chlorine plant and will not require any additional chlorine storage at the ETP. Following chlorination the treated water will pass through the Treated Water Storage to provide the required contact time. Treated water storage: The storage will be lined and covered to prevent contamination and provide a fixed volume contact basin for chlorine contact time requirements. The storage will also provide balancing of flows between the ATTP and the OPS for smooth ramping up and down of flows, and short-term emergency storage. Outfall pump station: This pump station is an existing asset and includes 3 duty and 2 standby pumps. The OPS peak capacity sets the peak flow requirements for the ATTP. The level of the OPS pumps also provides the fixed end level for the ATTP hydraulic profile. Residuals management: Since tertiary filtration is specifically designed to remove residual suspended solids from the secondary effluent, it will naturally retain these on the filter and they will be removed along with a small proportion of the BMF fixed film biomass by routine filter backwashing (typically each filter cell is backwashed once per day).


This backwash stream will be flow balanced and fed at a steady flow to a dissolved air flotation thickening (DAFT) process (similar to that already used at ETP for thickening waste activated sludge from the secondary process). Polymer and ACH coagulant will be used to improve DAFT performance. Clarified water from the DAFT will be returned to the Forebay area of the EHBs. Apart from any small amounts of coagulant and polymer which may be used as part of the DAF thickening process, these solids (equivalent to around 3% of the current plant total) will essentially be the same as the plant’s existing secondary waste activated sludge stream and will be treated accordingly. Following stabilisation in the digesters (producing additional biogas to power the process), the digested biolsolids will be discharged to the existing drying pans, where they are dried using the action of sun and wind and harvested for stockpiling prior to any beneficial use. As part of the current upgrade to the Winneke Water Treatment Plant at Sugarloaf Reservoir, a residuals management strategy has been developed, which will see the alum sludge produced from the water treatment process dried by centrifuge at site, rather than the current arrangement of transferring by sewer to ETP. Separating this Winneke residuals stream will allow pursuit of alternate beneficial use options for it, and decrease the solids load to ETP. This reduction in biosolids production at ETP will directly offset that associated with tertiary, resulting in no net change for ETP biosolids production. Provision for pH/Alkalinity correction: Hydrated lime dosing will be provided at the inlet to the ATTP to ensure correct pH and alkalinity at all times. Power supply and distribution: The ATTP will have a stand alone 22kV electrical network fed by an additional feeder to the ETP to be provided as part of a site power supply upgrade project. The additional power demand from the ATTP is approximately 4.5 MW. Control system: The ATTP control system will integrate with the existing ETP Siemens PCS7 system and be controlled from the existing Control Centre at ETP with provision for local control as required. Odour Management: It is not anticipated that the implementation of the proposed process train will result in any measurable increase in odour generation at the site as none of the treatment processes are inherently odorous by nature. Any odour in the ATTP area is expected to be very low level and non-offensive.


The treated water quality expected from the process train described above is set out in Table 4-5 below.

Table 4-5: Comparison of Secondary Effluent and Advanced Tertiary treated water quality

Median Performance 90th Percentile Performance Parameter Units

Secondary Effluent

Advanced Tertiary

Treated Water3 Secondary

Effluent Advanced Tertiary

Treated Water3 UVT cm-1, 254nm 42 62 48 68 True Colour Pt-Co units 90 <15 120 <25 TSS mg/L 15 <2 30 <5 Turbidity NTU 6-7 1 15 <2 COD mg/L 70 40 95 65 CBOD5 mg/L 6 <2 14 <5 Ammonia-N mg/L 3 2 <0.5 <10 2 <2 Nitrite-N mg/L 0.6 2 <0.1 0.8 2 <0.1 Nitrate-N mg/L 11 2 14 16 2 19 Total N mg/L 17 2 16 23 2 20 Anionic surfactants (MBAS) mg/L 0.2 <0.1 0.4 0.1 Oil & Grease mg/L <5 <11 16 <21 Note 1: Oil and grease levels are likely to be lowered significantly by the proposed plant upgrade, however analytical method limitations make it difficult to fully specify this Note 2: Post commencement of ammonia reduction process in 2007. Loads of ammonia, TKN and total nitrogen were significantly higher prior to the secondary process changes Note 3: Includes the effect of completion of the additional aeration tanks to complete the ammonia reduction project in 2009/10

4.7.1 Cost of Preferred Advanced Tertiary Treatment Process

Project cost estimates for the implementation of the ATTP have been developed using a bottom-up cost estimation approach based on the design information outlined in the Concept Design Report and using the Risk Adjusted Nominal Estimation (RANE) methodology. The RANE P50 costs (AUD) for the proposed ATTP, which represent the most likely expected project costs accounting for known risks at Concept design stage, including construction cost escalation and inflation, are: • Total Capital Cost = $380M

• Annual Operating Cost = $8.9M

• Annualised Capital Renewals = $2.3M


4.8 Environmental Outcomes of Advanced Tertiary Treatment

4.8.1 Plume Visibility

The colour and turbidity of seawater are significantly lower than the colour and turbidity of the current secondary effluent thereby contributing to plume visibility. The proposed Advanced Tertiary Treatment process train has demonstrated the ability to remove suspended solids, apparent colour and true colour, bringing the colour of the water down towards drinking water levels. This level of treatment will address the risk of plume visibility by significantly reducing the suspended solids and true colour of the water being discharged, without the need for an outfall extension. The current secondary effluent discharge at the existing nearshore outfall results in plume visibility at up to 50:1 dilution (seawater:effluent). Based on the hydrodynamic modelling this dilution is estimated to occur within 800m either side (east and west) of the nearshore outfall and 500m offshore. With the improvements to the colour and solids offered by advanced tertiary treatment, it is estimated that a dilution of only around 7:1 is required to match background seawater levels. The near-field plume model indicated an initial dilution of around 3:1 in the zone of initial dilution radius of 5-6 metres. The highest resolution hydrodynamic modelling has a minimum cell size of some 90m, and the median dilution within the cell at the outfall was 9:1. Interpolation within the cell indicates 7:1 would be achieved within around 60-70 metres radius. Other contributors to plume visibility such as biological foam and surfactants are also comprehensively addressed by the advanced tertiary treatment process, further reducing the risk.

4.8.2 Particulate matter

The major reduction in peak suspended solids and turbidity levels means that there will be significantly less organic material available for utilisation by biota, such as the exotic sand worm Boccardia proboscidea, which have opportunistically colonised the Boags Rocks area. This will reduce the coverage of opportunistic species and have a positive effect on the biological assemblages. In addition, the particulate material removed tends to concentrate any residual low solubility toxicants, and hence the upgrade will also provide an additional margin of safety over and above that already provided.


The solids contribution to current plume visibility and water clarity issues will be addressed.

4.8.3 Litter

Advanced Tertiary Treatment process train will remove all litter through deep bed media filtration.

4.8.4 Foam

Advanced Tertiary Treatment will remove all activated sludge plant related foam as well as reduce any residual foam forming potential to a level comparable to tap water. This will also address the contribution of foam to plume visibility and odour.

4.8.5 Oil and Grease – Fat Balls

Advanced Tertiary Treatment process train will reduce fat, oil and grease and address the formation and quantity of fat balls, because the larger particles thought to be the most likely contributor will be removed by the filtration process. The advanced tertiary process has an additional benefit in that the ozone is expected to oxidise organic material, with the smaller particles being removed by the biological media filtration. This will provide a further barrier against any dissolved material that may be contributing to fat ball formation. The results of the treated water sampling from the Trials have been below limits of detection for oils and grease.

4.8.6 Odour

Advanced Tertiary Treatment process train will significantly reduce odour through a combination of ozone oxidation and biological media filtration. Ozone-BMF Treatment has shown a 60-70% reduction in odour is achievable compared with the current effluent. The process also improves the odour character from unpleasant to more neutral tones. Additional odour reduction benefit is provided by reduction of foam which is currently a contributor to odour perceptions at Boags Rocks.

4.8.7 Mixing Zone Outcomes

The proposed process train will reduce the toxicity of the discharge at Boags Rocks through a combination of further reduced ammonia levels (typically <0.5 mg/L as ammonia-N) and a broad spectrum barrier to other minor toxic components of the ETP effluent other than ammonia. The most sensitive species for ammonia toxicity is consistently protected by the advanced tertiary process, leaving only residual freshwater effects which are addressed by a safe dilution of 20:1 for the most salinity


sensitive test (scallop larval development). Hydrodynamic modelling indicates the 20:1 safe dilution is achieved within a radius of 250m from the discharge point. The reduction in the already low levels of trace contaminants provides additional security against bioaccumulation potential.

4.8.8 Pathogen reduction

The proposed Advanced Tertiary Treatment process train will provide broader disinfection effectiveness and will further reinforce the "very good" microbiological water quality classification in the vicinity of the outfall, and lead to a year-round most favourable rating of local bathing water quality under the Draft WHO Recreational Water Guidelines. The results from the QMRA indicate that following the implementation of advanced tertiary treatment, all sites surrounding Boags Rocks will readily yield the highest recreational water quality classification. The production of high quality recycled water suitable for “Class A’ applications offers greater flexibility in terms of implementing recycling. It means that any potential user could draw a high quality recycled water supply from either the Eastern Treatment Plant or anywhere along the length of the South East Outfall or other distribution pipelines constructed. Increased diversions to recycling applications will continue the decline in freshwater and nutrient loads to the marine environment which have been achieved in recent years.

4.9 Key Conclusions

• A wide range of tertiary and advanced tertiary treatment alternatives at ETP have

been investigated and the leading candidates trialled to ensure a robust basis for design, costing, performance assessment and decision making.

• The tertiary technology trials conducted over the past 12 months have provided Melbourne Water with essential information necessary to make an informed decision as to the preferred process train to upgrade ETP.

• For the ETP application with its unique water quality characteristics, discharge point and scale, it was found that an advanced tertiary process offered greater benefits than a conventional tertiary filtration approach.

• The additional benefits for the marine environment offered by the Advanced Tertiary process trains were found to be significant. The additional ammonia reduction, and barrier to potential toxicants, and improvement to the key aesthetic parameters are


attractive features, both for receiving waters and facilitating customer acceptance and uptake in recycled water applications.

• The preferred advanced tertiary process for ETP consists of Ozonation and Biological Media Filtration (BMF), followed by Ultraviolet (UV) and Chlorine disinfection.

• The RANE P50 costs for the proposed ATTP, which represent the most likely expected project costs accounting for known risks at Concept design stage, are: - Total Capital Cost =$380M - Annual Operating Cost =$8.9M - Annualised Capital Renewals =$2.3M

• Advanced tertiary has the ability to reduce colour (which together with suspended solids and turbidity are key contributors to plume visibility), odour and residual foam formation potential. Water clarity and plume visibility issues are addressed.

• Advanced tertiary also offers all of the other benefits of a typical tertiary filtration process, including the elimination of litter, reducing turbidity and suspended solids, oil & grease, biological foam, and reducing the risk to recreational users of the marine environment via the enhanced disinfection processes.

• The biological media filters remove suspended solids and turbidity which contribute to plume visibility and the current proliferation of the spionid worm Boccardia at Boags Rocks.

• The multiple disinfection barriers facilitate recycled water use in sensitive ‘Class A’ applications.

• With completion of the ammonia reduction project (early 2010) and advanced treatment upgrade (late 2012) the following outcomes will be achieved: • Ammonia 0.5 mg/l (median), 90th percentile <2 • Total Nitrogen 16 mg/l (median) – a 60-70% reduction in nitrogen loads from mid

1990s levels – lower nutrient exposure for intertidal platforms • The most sensitive species for ammonia toxicity is consistently protected by the

advanced tertiary process, leaving only residual freshwater effects which are addressed by a safe dilution of 20:1 for the most salinity sensitive test (scallop larval development). Hydrodynamic modelling indicates the 20:1 safe dilution is achieved within a radius of 250m from the discharge point.

• Broad spectrum protection against bioaccumulation and risk of other toxicants • Continued H. Banksii recovery facilitated

• The advanced tertiary upgrade provides a ‘future-proof’ process train that allows for the later addition of ultrafiltration and reverse osmosis membranes, if future recycled water customer or regulatory needs require it.

• The standard of treatment and associated comprehensive environmental benefits, is a major change from that envisaged under the original Works Approval.


Extending the South Eastern Outfall to relocate the discharge from the current

near-shore location and increase dispersion through a higher degree of initial

dilution is one option for reducing the current marine impacts, either alone or

in combination with additional treatment measures. This section describes

what is involved in constructing such an extension, it’s impacts, costs, and

benefits to the marine environment.

5.1 The Current Outfall Arrangements

The South Eastern Outfall (SEO) is 57 km long and extends from ETP to discharge into Bass Strait at Boags Rocks on the Southern Mornington Peninsula. The existing outfall extends some 30-40 m into the surf below the low water level. The SEO begins with a 10.3 km section of 2.1 m diameter rising main where effluent is pumped to the first tunnel section at Frankston. From here the SEO flows under gravity (grade 1 in 870) to Boags Rocks. The Outfall Pump Station (OPS) is located at ETP and contains a series of pumps. Typically one or two pumps operate to discharge dry weather flows, and three pumps can operate to discharge wet weather flows. The SEO includes four tunnel sections that are connected by pipelines and an ocean discharge section. The two longest tunnels are the Frankston Tunnel (5.2 km) and the Dromana Tunnel (7 km). In the last 4km of the SEO at the beach end there are two shorter tunnels (less than 1 km each).

Pumps

10 km rising main, 50m lift(2.1m dia) to Frankston

Series of pipes & tunnels, varying in grade & diameter, linked by access points, some with drop shafts

Trueman’s Rd Access857m from end

6.5m drop

Last Access (in dunes) 167m from end

Low water mark

2.8m dia

3 outfall pumpsmax 8m3/s

Figure 5-1: Simplified conceptual model for the hydrology of the Outfall

5. Extending the Outfall


Some parts of the SEO were constructed to allow for a duplication of the original capacity, in particular the tunnels and Y-junctions. The current capacity is limited to that of the rising main and is 700 ML/day (8.1 kL/s) with three pumps operating. The maximum foreseeable capacity requirement for the SEO is 10kL/s, which would involve the operation of a fourth pump set in the OPS. This is equivalent to the theoretical capacity of the gravity pipeline sections and were it to be required would require the duplication of portions of the existing rising main with a smaller diameter main.

5.2 Extending the Outfall

An updated concept design and cost estimate for the South Eastern Outfall (SEO) Extension has been undertaken (GHD 2009). This is based on the 2003 EPA Victoria Works Approval requirement to relocate the discharge point offshore by a minimum of 2 km. The Outfall Extension concept is to discharge the effluent into Bass Strait via multiple diffuser heads at a seawater depth of 20 to 30 m, approximately 2km offshore, on a similar alignment to the current outfall. In order to achieve this, several key elements are required including a conduit (tunnel) starting at an on-shore shaft, a diversion structure to divert the flow from the existing SEO into the shaft, multiple diffuser heads anchored to the seabed with multiple ports and multiple risers to link the tunnel to each of the diffuser heads. The effluent will be released through the diffusers close to the seafloor. The SEO Extension involves constructing a 2.8 m diameter tunnel under the seabed. The tunnel would commence approximately 800 m back from the shoreline. The tunnel would begin at the base of a 25 m deep shaft and be approximately 3.2 km long in total. An aerial view of the site and tunnel orientation is shown in Figure 5-4. The tunnel is connected to a series of six diffusers located on the seabed, via cross passages and risers. Each diffuser has eight ports. The risers are evenly spaced over a length of approximately 360 m and are located in water approximately 20 to 30 m deep. This provides an initial dilution of 50 to 1. Limited geotechnical information is currently available for the site. Consequently, if the project was to proceed, a detailed geotechnical investigation will be required. This would include onshore, horizontal core drilling and offshore works. Environmental, planning and cultural heritage approvals will all be required under Commonwealth, State and local government legislation. These approvals will be


necessary for the geotechnical work as well as the construction activities. Purchase of Net Gain offsets for native vegetation removal may be required. Additional detail is provided below and in the attached Concept Report (Appendix 6)

5.3 Construction Aspects

5.3.1 Geotechnical Investigations Required

The scope of the required geotechnical investigation is divided into three stages: • Stage 1: Onshore Geotechnical Investigation, which will consist of borehole

investigations to extend knowledge of the subsurface profile to allow 3-dimensional geological and geotechnical modelling of the shaft site, onshore tunnel alignment and ancillary structure footprints.

• Stage 2: Horizontal Core Drilling (HCD) to obtain information on rock hardness and presence of faults along the tunnel, and

• Stage 3: Offshore Geotechnical Investigation to obtain sufficient reliable seabed information on the site conditions to permit the safe and economic design of installation and permanent works.

Unexpected or poorly defined site conditions are one of the most commonly re-occurring causes of construction delays and cost escalations. By undertaking a detailed site investigation as part of an integrated seabed risk management process, the risk of delays and increased costs would be reduced. Offshore projects can be particularly exposed to seabed risk due to the relatively wide spacing of individual structures and the increased influence of metocean conditions in shallow water. In addition, projects are often located in areas where there is little or no existing knowledge of the seabed or environment such as the area surrounding Boags Rocks. The staged investigation is designed to provide the following information: • Cores along the alignment of the tunnel. However, this will not be possible for the

entire length because the HCD technique will not be able to progress for the approximate 3200 m length of tunnel.

• Distribution of subsurface formations. • Strength and engineering characteristics of subsurface formations. • Presence of structures within subsurface formations that may present geological

hazards to tunnel construction • Permeability of rock mass in formations


• Onshore geological plan • 3-D geological model with offshore projection along the alignment of the outfall

extension • Hydrogeological model • Water depth and Bathymetry • Near surface soil conditions and their lateral variation • Debris or man-made hazards across the proposed site

5.3.2 Main Works Site

A cleared site area of approximately 150 m x 150 m is required for the shaft and tunnel works (see example photos below for shaft work sites on similar tunnelling works for the Northern Sewerage Project).

Figure 5-2: Example of smaller shaft construction site on the NSP


Figure 5-3: Acoustic enclosure & part of works area at Brearley Reserve shaft site on the NSP


Figure 5-4 Alignment of an extended outfall and works site location

5.3.3 Construction of a site access road and supply of high voltage power

Construction of a site access road suitable for heavy equipment, materials delivery and spoil removal will be required. Currently there is limited power available at the Boags Rocks site. To allow for construction and ongoing operation of the purging pumps there will be a need to provide power. Construction power could be in the form of a diesel generator, however there will be a need for ongoing power for the purge pumps. The nearest high voltage substation is located near the Rosebud shopping centre.

5.3.4 Shaft construction

The tunnel construction requires a minimum 10 m diameter shaft. The depth of the shaft is 25m. The shaft is required to be constructed before the tunnel can commence. Various construction techniques could be used depending on the geotechnical conditions. For the purposes of this design and cost estimate it has been assumed the


construction technique used will be “diaphragm wall”, which is better suited to generally poor ground conditions than, say, the secant pile technique. The assumed thickness of the diaphragm wall is 1 m. The upper part of the shaft will accommodate the purging pump station.

5.3.5 Tunnel construction using a tunnel boring machine

A segmentally lined concrete tunnel of 2.8 m internal diameter. This diameter is considered the smallest practical size for a tunnel of this type and can accommodate the maximum design flow rate. A “downward sloping” tunnel, starting in the area immediately outside the National Park and sand dunes area, reduces the impact of construction activities on the more sensitive environmental areas.

5.3.6 Jack-up Drilling Barge

Use of a jack-up barge is required for offshore borehole drilling for geotechnical investigations, pre-grouting at designated locations along the tunnel, drilling of risers and installation of diffusers. Examples are shown in the images below.

Figure 5-5: Example Jackup drilling barge


Figure 5-6: Example Jackup drilling barge

5.3.7 Diffusers, Risers and Cross Passages

Each riser and diffuser is considered as an item because they cannot function independently. The number and spacing of the diffusers arises from hydrodynamic modelling of the ocean and the initial dilution required to minimise environmental impacts. Modelling is undertaken to determine the preferred arrangement and number of risers and diffusers to achieve the desired initial dilution of 50:1. The modelling indicated the need for 6 diffusers, each comprising 8 number 400 mm diameter ports. The ports do not have valves. The risers are evenly spaced over the length of approximately 360m long with diffusers located in water approximately 23 m deep, or deeper. The risers comprise vertical “tubes” of 1.2 m in diameter. They are often fabricated from glass reinforced plastic (GRP) and are installed into a hole drilled from the offshore jack-up drilling barge. Each riser is linked to the tunnel by a cross passage which may be 10 to 20 m long depending on tolerances.

5.3.8 Seawater Purging Structure and Purging Pipeline

The existing SEO was not designed to be extended into deep water. Excess pressure head available at the coastline is suitable for the existing outfall, but it is not necessarily adequate for the Outfall Extension. In broad terms, the Outfall Extension will require more pressure head at the coast than the existing outfall.


At high tide the “excess” pressure head at the coastline is approximately 2.5 m. When the SEO is operating under a constant flow of 8.1 kL/s, this is sufficient head to drive the flow into Bass Strait through the Outfall Extension when the tide is high (1.51m AHD). The Outfall Extension involves discharging fresh (non-saline) water into the sea at depths of approximately 25 m. This arrangement requires additional pressure head relative to the existing outfall in order to: • Make up for additional hydraulic losses which are associated with an extended

outfall • Overcome the weight of the seawater, which is heavier than the fresh water being

discharged, in the water column above the deepest part of the tunnel. Approximately 1.2m of pressure head is required for this aspect alone

A purging structure and pipeline is needed to remove saline intrusion which will occur during periods of low flow or zero flow in the SEO, (e.g. during maintenance periods). Saline intrusion is undesirable as it creates an additional driving head and requires a significant flow rate above normal to purge the intrusions. In addition, saline intrusion can lead to marine and other growths in the tunnel and risers which can adversely affect performance. The purging structure is located above the shaft and contains a pump station with flow bypass facilities. The purging pipeline is, nominally, 900 mm in diameter. It starts in the purging structure, is aligned within the tunnel and ends at the start of each of the cross passages.

5.3.9 Diversion Structure

A diversion structure connecting the current outfall pipe to the new extension at the shaft site is required. This involves a large subsurface concrete junction pit with penstocks for flow control and isolation.

5.3.10 Odour Control Facilities

To address associated odour risks with the purging structure which would be located in the vicinity of the south east corner of the golf course, an odour control facility has been allowed for. Due to its location, this facility cannot generate a waste stream, limiting the normal range of odour treatment options. One possible approach is an activated carbon filtration system. The odour control facility would need to take into consideration visual amenity. There is still an inherent risk of odour from this structure caused by fugitive emissions from the purging structure, particularly if the


odour is not reduced in the effluent through some form of treatment. Advanced tertiary treatment is likely to address this.

5.3.11 Programme and Capital Cost

A six year project timeframe has been envisaged. The first two years involve environmental and project approvals, geotechnical investigations and detailed design. A four year construction and commissioning period has then been allowed for. The size of the project, sensitive location, uncertain geotechnical conditions, and difficult offshore construction conditions (exposed location, wave climate etc.) are significant influences on the construction period. A risk adjusted nominal estimate (RANE) was developed for the SEO Extension. This process involved determining a base estimate and then assessing inherent and contingent risks as part of a risk analysis process. The P50 Cost Estimate is $399 Million.

5.3.12 Operation and Maintenance

Operation and maintenance of the SEO Extension would involve the following activities: • Civil, mechanical and electrical maintenance activities related to the shaft, purging

pump station and odour control facility. Incorporated into these facilities will be a water level and flow monitoring system.

• Inspection and cleaning of the diffusers using divers or a remotely operated vehicle (ROV)

• Inspection of inlet shaft and outfall tunnel using ROV • The annual cost for the above activities is estimated at $500,000.

5.4 Environmental, Planning and Cultural Heritage Aspects of Construction

There are many environmental, planning and cultural heritage issues that will require addressing prior to the commencement of any construction on the outfall extension and these approvals will also be required to undertake geotechnical investigations. Geotechnical investigations are a fundamental part of the design process and must be undertaken.


The southern coastal area of the Mornington Peninsula is environmentally sensitive and contains many areas of high conservation significance. There are a number of levels of protection relating to this area. The coastal fringe and some of the hinterland comprise part of the Mornington Peninsula National Park. There are also a number of planning controls that protect specific areas of environmental, archaeological and landscape significance in the area. Other natural and cultural assets in the area are protected via a range of legislation and policy. The environmental impacts of providing the powerline to the site, have not been considered at this stage. These impacts will need to be considered at the next stage of design. A brief summary of the environmental, planning, and cultural heritage issues is included below. The key issues related to the terrestrial environment include: • The cliffs and dunes are of high conservation significance and also of very high

archaeological significance. The ecological vegetation community (EVC) that inhabit the cliff tops and the exposed dune areas is Spray Zone Coastal Scrubland, a vegetation community that is considered rare in Victoria.

• The area “behind” the dunes contains extensive aboriginal middens of high cultural significance and a detailed archaeological field survey would be required. Permission to disturb these highly sensitive areas would likely be extremely difficult if not impossible to obtain. Hence it is proposed to have no construction in the dune or foreshore areas. The large middens that are so conspicuous along the dunes extend some distance inland, the exact extent of which is unknown in the absence of a detailed survey. A detailed archaeological field survey would be required to establish the extent of the middens and indeed other archaeological sites that may be present in the area.

• The vegetation in the area between the shoreline and golf course is of high conservation significance and net gain offsets may be difficult to find. This has lead Melbourne Water to propose the construction zone for the outfall to be moved to the golf course area to prevent disturbance to native vegetation.

• If the construction zone is limited to the golf course area then, disturbance to the native vegetation is substantially less than if construction is immediately behind the sand dunes, however it will require a longer tunnel to be constructed.

The key points about the marine environment are: • Ecological surveys of the marine environment have been undertaken;


• Construction impacts on the marine ecology are expected to be relatively short-lived and small in geographic extent the effects on the marine ecology during construction are likely to include:

• Fish- There are commercial fisheries in Bass Strait for species such as Whiting, Flathead, Ling and Gummy Shark. The commercial rock lobster fishery operates in areas around Cape Schanck and Abalone is also taken from around inshore reefs. A number of these fishes are listed as rare or threatened such as the Great White Shark. There is potential for construction works to impact upon the ecology of a range of these fishes although this would be expected to be a limited impact that is relatively short-lived (ie for the duration of the construction period only)

• Marine Mammals- Of particular importance are the migrating Southern Right Whales, and Blue Whales, which have been raised in other areas subject to construction in the Bass Strait. At the Nobbies on Phillip Island to the east of the construction area, is where the largest colony of Australian Fur Seals exists. These animals are likely to forage for fish in the area of the proposed outfall construction. Noise from construction activities such as blasting and the use of sonar are the main concerns in terms of impacts on marine mammals.

• Seabirds- The impact of construction on seabirds is likely to be localised and may not impact many birds apart from the Little Penguin. This bird feeds on pelagic fishes, particularly pilchards, in Bass Strait. Construction activities may disturb the feeding of the penguin in a localised area and this disturbance may persist for the duration of the construction

• Any seismic surveys for geotechnical investigations will need to be undertaken using the Environment Protection and Biodiversity Conservation (EPBC) Act Policy No 2 to minimise the impacts of seismic surveys on cetaceans.

5.5 Approvals

Environmental, planning and cultural heritage approvals will all be required under Commonwealth, State and local government legislation. A summary of the likely approvals that will be required is discussed below:

5.5.1 Environmental

A referral will need to be made to the Commonwealth under the EPBC Act 1999 outlining the potential impacts of the project on matters of National Environmental Significance. Any additional approvals required under the EPBC Act may be undertaken in conjunction with any Victorian approvals. The proximity of an anextended outfall to Commonwealth marine waters would likely trigger the EPBC Act and additional complex hydrodynamic modelling would likely be required to describe the plume behaviour.


An Environmental Effects Statement (EES) has been assumed to be required under the Environmental Effects Act 1987 as this is a significant project. A referral will need to be made to the Minister for Planning to determine whether an EES is required or not. Such a referral needs to be sufficiently detailed to allow for a decision to be made. As such, considerable work is required to inform the referral. Under the Environment Protection Act 1970 a licence to discharge at the new location will be required. Consent will be required under the Coastal Management Act 1995 in order to carry out works in coastal Crown land (onshore and offshore).

5.5.2 Planning

Planning approval is likely to be required for the proposal, including the removal of native vegetation, pursuant to the Planning and Environment Act 1987. The proposed works are subject to the Mornington Peninsula Planning Scheme, which include the following zones and overlays in the area which may constrain the works and where appropriate requirements must be met: • Green Wedge Zone • Public Conservation and Resource Zone • Environmental Significance Overlay 15 The Cups • Environmental Significance Overlay 22 Active Dunes • Environmental Significance Overlay 23 Semi Stabilized Dunes • Environmental Significance Overlay 24 Site Of Scientific Significance • Significance Landscape Overlay 2 Coastal Landscape • Significance Landscape Overlay 3 Scenic Roads In addition to the Approvals required by the Mornington Peninsula Planning Scheme, there are likely to be a range of Statutory Environmental Approvals required prior to commencing works, which are triggered by the following Acts: • Environment Protection and Biodiversity Conservation Act 1999 • Victorian Planning and Environmental Act 1987 • Victorian Flora and Fauna Guarantee Act 1988 • Victorian Environment Effects Act 1978 • Catchment and Land Protection Act 1994 (CALP Act) • National Parks Act 1975 • Crown Land (Reserves Act) 1978 • Land Act 1958 • Environment Protection Act 1970 • Coastal Management Act 1995


In assessing the potential impacts and benefits of the project, a range of national and state level policies and strategies must be considered. A summary of the relevant documents that will contain the policies and strategies for consideration is provided below: • State Environment Protection Policy (Waters of Victoria) • State Environment Protection Policy (Groundwaters of Victoria) • State Environment Protection Policy (Air Quality Management) • State Environment Protection Policy (Control of Noise from Commerce, Industry

and Trade) • EM 021-2005: Coastal Engineering Guidelines for Working with the Australian Coast

in an Ecologically Sustainable Way • Victorian Native Vegetation Management Framework 2002

5.5.3 Cultural Heritage

It is likely that a Cultural Heritage Management Plan (CHMP) under the Aboriginal Heritage Act 2006, will be required for the proposed works. At present there is no Registered Aboriginal Party (RAP) for the locality, therefore a CHMP would be determined by Aboriginal Affairs Victoria (AAV). An assessment by a suitably qualified heritage consultant will need to be carried out, to determine the potential impact of the proposal on cultural heritage. The areas surrounding the proposed works, including the geotechnical investigations, are located within Cultural heritage sensitivity as identified on the Aboriginal Affairs Victoria (AAV) mapping. Any construction required would be subject to Section 43 division 5 of the Aboriginal Cultural Heritage Regulation 2007 as a ‘utility installation’ is defined as a ‘High Impact Activity’ (i.e. projects which cause significant ground disturbance). Projects which are considered to be ‘high impact activities’ within areas of Cultural heritage sensitivity will require the preparation of a Cultural Heritage Management Plan (CHMP) in accordance with the Aboriginal Cultural Heritage Act 2006 and the Aboriginal Heritage Regulations 2007. In addition to aboriginal cultural heritage, there was a search performed on post contact heritage items in the following databases • National Heritage places, Commonwealth Heritage places and places on the

Register of the National Estate (RNE) searched using the EPBC Act Protected Matters Search Tool;

• The Victorian Heritage Register; and


• Heritage Overlays for the Mornington Shire Planning Scheme. The search indicated that no World Heritage Places, Commonwealth Heritage Places or National Heritage Places have been recorded within the study area. However the site and surrounding area is on the Register of the National Estate. This area applies to the ‘Cup Country’ the ‘Cape Schanck Coastal Park and the Cape Schanck Landscape area’. The coast is also identified as a ‘protected area’, which applies to the Mornington Peninsula National Park. No heritage overlays are within the area that would be used for construction.

5.6 Outcomes for the Marine Environment

The outfall extension assists in the recovery of the marine environment by relocating the discharge point away from the rocky platforms at Boags Rocks to a point 2km offshore. The design of the outfall is to increase the initial dilution to provide a minimum dilution of 50:1. All of the benefits to the receiving environment are achieved through increased dilution and relocation of the discharge point away from the area used for recreational enjoyment by the community.

5.6.1 Ecological Impacts on Intertidal Rocky Platforms

The ecological impacts in the receiving environment have been discussed in Section 2 and can be attributed to suspended solids, ammonia, nitrogen, and freshwater from the current discharge. The outfall extension provides good opportunity for recovery of the rocky platforms, primarily through the relocation of the discharge away from the intertidal zone, with the greatest benefits being seen at Boags Rocks, which is also the site which has shown the greatest impact. Beyond the immediate vicinity of the outfall the effluent should already be sufficiently diluted by the extended outfall to eliminate toxic effects. With the relocation of the discharge from the intertidal area the benthic communities in area surrounding the existing outfall should revert to a composition and structure similar to those that inhabit neighbouring reefs. The process of re-establishing the community may take around five years with some external assistance potentially being required to establish macroalgae such as Hormosira and Durvillaea due to the low dispersal capabilities of these algae. The brown algae is expected to take the longest to return to Boags Rocks due to the current cover of turfing algae, however a greater diversity of algae would be expected to occur if the discharge is moved offshore.


It is expected that there would also be a gradual return of these species to other sites impacted by the current ETP discharge, including Fingals beach.

5.6.2 Suspended Solids

The outfall extension will address the impacts at Boags Rocks and the surrounding environment caused by suspended solids and particulate organic carbon through increasing the dilution of the effluent in the marine environment and relocating it away from the rocky platforms. Colonization by the worm Boccardia probosidea has resulted in a layer of muddy sand, 1 to 20 cm thick on the substrate, making it unsuitable for many reef-dwelling species. It seems likely that Boccardia itself thrives only near the Outfall because of the elevated levels of organic particulates in the current secondary effluent. Extending the outfall will remove the particulate organic carbon which is a food source for the Boccardia and it is expected that over time, these solids that are currently deposited on the rocky platforms will be reduced by natural marine processes. The increased dilution offered by the extended outfall would limit the risk of Boccardia recolonising offshore as the particulate organic carbon will be dispersed over a much wider area than currently occurs.

5.6.3 Nutrients

Removing the discharge from Boags Rocks is also expected to assist with the impacts caused by nutrients, on a range of species including Ulva. In the sublittoral fringe and shallow subtidal region it is hypothesised that increased nutrients increase the growth rate of turfing algae (especially Pterocladiella capillacea) making them more likely to out-compete limpets (especially Patella peroni) for space. Boags Rocks has a greater level of turfing algae than other non impacted sites. Reducing the nearshore nutrient levels through increased dilution via an extended outfall is expected to assist with reducing the proliferation of the turfing algae around Boags Rocks.

5.6.4 Freshwater/Salinity

During toxicity testing with ETP effluent it was found that scallop larval development was the most sensitive test to reduced salinity, with no inhibition seen at salinities of 34‰ and above. The initial dilution provided by the outfall extension of 50:1 is at


such a level to ensure that the salinities are greater than 34‰ and that freshwater does not inhibit scallop larval development outside the zone of initial dilution the area within a radius of 100m above the diffusers area of the outfall.

5.6.5 Contaminants

Comparison between the impacted sites and a reference site suggests that biota at Boags Rocks appear to be accumulating low levels of copper, however this is not an issue of concern at the present time. Should contaminant accumulation in the receiving environment become an issue in the future, the outfall extension will not be able to address this risk on it’s own. It will be necessary to include some form of treatment at ETP to remove the contaminants from the effluent prior to it entering the marine environment.

5.6.6 Aesthetic Impacts

The outfall extension will influence the aesthetic impacts associated with the current discharge at Boags Rocks through increased initial dilution and relocation of the discharge point 2km offshore. This distance from the shoreline will remove the visibility of the effluent discharge from the users of the environment immediately around Boags Rocks. The increased dilutions from the extended outfall will ensure that there is no visible plume at the shoreline caused by either effluent colour or the buoyant nature of the freshwater discharge entering the marine environment. The discharge point being 2km offshore and at a depth of 30m means the plume will not be visible from the beach or cliffs adjacent to Boags Rocks. Analysis of the expected colour and turbidity levels at the shoreline based on dilutions from the extended outfall shows levels unlikely to be detectable beyond background levels. Without additional treatment to reduce colour and solids, a plume may be detectable at a relocated discharge point 2km offshore. The current secondary effluent has an earthy musty odour. Extending the outfall by 2km offshore will lead to diluted effluent being released offshore, into a less energetic marine environment. The combination of increased distance from the shore, and the increased dilution of the effluent with seawater, is expected to reduce odour significantly, so that it would be unlikely that the odour would be detected around the beaches adjacent to Boags Rocks. If the outfall is extended there will be odour control provided at the purging structure located within the golf course, which will also eliminate a potential source of odour. There is a small residual risk of odour from the


purging structure caused by fugitive emissions (if the effluent receives no additional treatment to reduce odour). The extended outfall will disperse any litter that may not be captured by screens, and hence remain in the ETP effluent, over a wider area than currently occurs, and with the discharge point being 2km offshore, the risk of litter from ETP washing up on St Andrews and Gunnamatta beaches will be substantially reduced. Additional tertiary treatment would ensure no litter in the effluent. The outfall extension will dilute any foam that may be present in the effluent, reducing the risk of foam from the treatment plants being washed up or present on St Andrews or Gunnamatta beaches. The outfall extension does not remove the biological foam formers or surfactants from the effluent and hence there remains some risk with this aspect, unless additional treatment was provided. An extended outfall reduces the potential for air entrainment. Effluent is discharged at depth some 2 km from the shore and then through a series of diffusers that enable faster dilution into the surrounding water column as opposed to the present situation where the effluent is discharged closer to the surface and shore where there is vigorous wave action and features such as reefs. Any foam created upstream in the pipeline could be discharged at this location 2 km from the shore and rise to the surface (if any remains after pressurisation in the pipe). Although transport of any such surviving foam by wind to the shore might in theory occur, it is likely that due to the distance involved the foam would become dispersed over a wider area and not impact on the beaches as currently occurs. Due to the increased dispersion and dilution expected from such an outfall, the occurrence of fat balls on the beach is expected to reduce. Fat balls are transported by currents, tides and wind, and are buoyant. After discharge from the diffuser, these particles might rise to the surface, and be transported according to wind and tidal conditions. Similar to the case for litter, there potentially will be fewer fat balls washed ashore, but spread along a greater length of coastline. If fat balls require an energetic environment with collisions between particles to form then such an outfall would provide benefits due to the effluent being discharged at depth, well beyond the surf zone. Otherwise formation mechanisms may not be greatly inhibited. Owing to the composition of fat balls, it is expected that they will break down in the natural environment over time. Dispersion at a distance from the shore increases the


likelihood of fat balls breaking down before they can be washed ashore. As with litter, additional tertiary treatment would fully address the residual risk of fatballs.

5.6.7 Recreational Health

The current situation of secondary treated effluent coupled with a nearshore outfall provides an overall classification of Good to Very Good under NHMRC (2008) recreational water environment guidelines for beach and surf zones. To address the event based risk during peak wet weather operating conditions at ETP, a QMRA was undertaken which has been described in Section 2. An extended outfall would increase dilutions in the areas of recreational use such as Gunnamatta and St Andrews beaches, but they are insufficient to fully address the issues raised in the QMRA. Results from the QMRA suggests that the outfall extension option yields the highest quality classification for recreational water environments under dry weather, but a low quality classification under peak wet weather flow conditions. This can only be fully addressed by tertiary/advanced treatment. Even with increased dilution and die-off offered by the extended outfall and the discharge point being relocated 2km offshore, an extended outfall without any upgrade to the treatment process at ETP will not result in a Very Good classification under all conditions.

5.6.8 Mixing Zone Requirements for an Extended Outfall

The mixing zone requirements for an extended outfall are determined by the initial dilution offered by extended outfall and the ‘safe dilutions’ of effluent required to protect beneficial uses which have been determined through toxicity testing. An extended outfall will provide an initial dilution of 50:1 and with the outfall discharging 2km from the shoreline, this change in location will protect some beneficial uses by removing the discharge away from the nearshore and rocky platforms. The current ammonia reduction upgrade provides for achieving an annual median ammonia level of 5mg/L and a 90th percentile of 10mg/L. In combination with a dilution level of 50:1, this is expected to protect sensitive species from toxicity effects outside of the zone of initial dilution. With an extended outfall the zone of initial dilution of 50:1 will occur offshore immediately over the diffuser section of the outfall (approximately 360m long), and


would have a width of 100m either side of the diffusers to allow for plume movement as the buoyant freshwater rises to the surface. The total dimensions, allowing 100m from diffusers, is hence 560m by 200m. The rocky platforms around Boags Rocks have been impacted by the suspended solids, ammonia, and nutrients in the ETP discharge. As there are no intertidal rocky platforms in the vicinity of the discharge point from the extended outfall, there is no need for a further specific mixing zone to address the issue of nutrients.

5.7 Key Conclusions

• The existing outfall at Boags Rocks extends some 30-40m into the surf, below the

low water level. The concept of extending the outfall is to discharge the effluent around 2km offshore in 20-30m of water depth through a series of diffusers.

• To extend the outfall it will be necessary to construct a 2.8m diameter tunnel from an area near the golf course, extending under the sand dunes and national park area and under the seabed approximately 2km from the shore.

• The tunnel construction requires a minimum 10m diameter shaft to be constructed, and the depth of the shaft will be around 25m. A cleared work site for construction of the shaft will be required which will be around 150m x 150m. There will be a need for a site access road to be constructed suitable for heavy traffic and the provision of power to the site for both construction and ongoing operation of the outfall.

• The design, approvals and construction program is expected to take around 6 years. The first two years involve environmental and project approvals, geotechnical investigations and detailed design. A four year construction and commissioning period has been allowed for.

• There are extensive environmental approvals required relating to cultural heritage, terrestrial and the marine environment in the area surrounding the outfall. It is expected that an Environmental Effects Statement (EES) will be required.

• The benefits to the marine environment through the extension of the outfall are achieved through increased dilution of the effluent with seawater. This principal of increased dilution applies to all of the environmental impacts caused by suspended solids, nutrients, freshwater and aesthetics.

• The outfall extension without additional treatment is unable to reduce contaminant or pathogen loads.

• The outfall extension without additional treatment yields a low quality classification under peak wet weather flow conditions. This can only be fully addressed by tertiary/advanced treatment.

• The design of the outfall will achieve an initial dilution of 50:1 within a zone approximately 560m by 200m. Moving the discharge away from the rocky platform


at Boags Rocks will assist with the process of re-establishing benthic communities that inhabit the rocky platforms. This process may take up some years as it will be necessary for the turfing algae to reduce and then allow for the re-establishment of the brown algae such as Hormisira and Durvillea.


The range of challenges faced, and complex multi-faceted aspects of the

decision making environment for this project are evident from the discussion

in the preceding sections. It is apparent that assessing and integrating the

many factors at play requires a Triple Bottom Line approach to arrive at a

practicable solution which balances the at times potentially competing drivers

and environmental, social and economic values.

This section includes discussion of the TBL assessment including framing the

scenarios for assessment, the criteria against which they are assessed, the

basis for scoring, and outcomes and conclusions for the preferred scenario.

6.1 Triple Bottom Line Assessment

Melbourne Water has used a Triple Bottom Line (TBL) assessment of the options to assist in determining the preferred combination of treatment and outfall to meet all of the competing requirements. The scoring was approached taking into consideration the likely perspectives of the various stakeholders based on extensive consultation and interaction over the course of the last 10 years. The criteria that were used as part of the TBL assessment were developed from the Melbourne Water ‘Effects Significance Table’ which is part of the TBL guidance notes, and the key aspects relevant to the project from the Environment Protection Act 1970 and the State Environment Protection Policy (Waters of Victoria). The Environment Protection Act 1970 principle of Integration of Economic, Social and Environmental considerations is central to the TBL approach - the measures adopted should be proportional to the significance of the environmental issues being addressed. The Economic criteria that each scenario was assessed against are summarised as follows: 1. Net Present Cost – calculated from the capital and operating costs associated with

each scenario 2. Impacts on local/regional economy - What impact does this option have on new

business opportunities and local economy? Considers significance of expenditure and construction activity and degree of local content.

6. Assessing The Options


The Social criteria that each scenario was assessed against are summarised as follows: 1. Access - What impact does the option have on access to public or private space

and the need for land rezoning? Impacts are focussed on construction phase and need for exclusions zones, restricted access, need for construction compounds etc. where public may otherwise freely access.

2. Cultural Heritage - What impact does the option have on aboriginal sites of importance or historic buildings, sites and significant landscapes?

3. Community Expectations on Treatment, Safety & Amenity - How does the option address public perceptions and preferences with regard to an acceptable wastewater treatment standard and effluent quality to facilitate enjoyable use of the area as impacted by the discharge (recreational health, plume discolouration, odour, litter, oil & grease, foam)

4. Strategic Community Benefit to future recycling - Contribution to cost effective recycling development (removal/creation of barriers for future recycling development)

5. Consistency with Policy & Community Attitudes - Does the option fit with community attitudes to water resources management, Government Policy (Central Region Sustainable Water Strategy, Our Water Our Future ,etc) and Melbourne Water Policy (Statement of Obligations, Strategic Framework, Environment Policy, Public Health Policy)

The TBL Environmental criteria focus on the science behind the criteria for each scenario and the key relevant clauses from the SEPP (Waters of Victoria). The questions asked for this section are as follows: 1. Waste Hierarchy - How does the option fit with requirements of the waste

hierarchy 2. Beneficial Use – Aquatic Ecosystems. Does the option support the return to largely

unmodified environment for Open Coast segment? 3. Beneficial Use - Water based Recreation. Does the option make the water suitable

for primary and secondary contact? 4. Beneficial Use - Water based Recreation. Does the option address SEPP aesthetic

requirements? 5. Beneficial Use - Cultural and Spiritual Values. Does the option consider the values

held by communities (water based) 6. Beneficial Use- Water for Aquaculture. Does the option make the water suitable for

production of fish, crustacea and molluscs for human consumption


7. Management of discharges to Surface Waters - does the option consider the use of 'best practice' and appropriate combination of technology & process to reduce the impacts

8. Management of discharges to Surface Waters- Ensure effective wastewater management practices to minimise risks to aquatic ecology. Does the option produce a discharge that results in acute toxicity impacts? Are there chronic effects likely outside the mixing zone?

9. Existing Wastewater Discharges- Where a discharge cannot be avoided it must be below the low water mark and should be beyond the surf zone. Is the discharge beyond the surf zone?

10. Existing Wastewater Discharges - Does the option maximise wastewater avoidance and re-use opportunities?

11. Mixing Zones - minimise the impact by keeping the mixing zone as small as possible - show continuously improving environmental management - does the option reduce the size or eliminate a mixing zone?.

12. Greenhouse – What impact does the option have on greenhouse gases if not offset?

13. Adverse impacts during construction - Includes dust, diesel, sediment runoff, flora & fauna, traffic, noise

The TBL assessment ranks each of the scenarios relative to the base case with the base case being scored as 0 and then each scenario is scored relative to this on a scale of -4 to + 4. Where any potential existed for overlap in criteria (e.g. between some of the environmental and social criteria) the weighting has been split to avoid ‘double dipping’ and delineation and focus created in framing the questions, explanatory material and scoring. The ranking on the scale relative to the base case is as follows: +4 Very much better +3 Much better +2 Moderately better +1 Little better 0 No change or equivalent to the base case -1 Little worse -2 Moderately worse -3 Much worse -4 Very much worse


Overall results are expressed relative to the base case as being more or less acceptable. Positive results are favourable and negative are less favourable.

6.2 Basic Assumptions

All scenarios assume the ammonia reduction project is completed and in operation. The TBL was based on the Melbourne Water standard TBL spreadsheet and scored in accordance with the guidelines. Weighting preference was given to most directly relevant criteria, and a wide range of sensitivity cases were examined, with summed % weightings to each section as follows:

Economic 43 40 40 35 30 30 25

1 41 38 38 33 28 29 24

2 2 2 2 2 2 1 1

Social 15 15 20 15 20 15 20

1 2 2 3 2 3 2 3

2 2 2 3 2 3 2 3

3 3 3 4 3 4 3 4

4 4 4 5 4 5 4 5

5 4 4 5 4 5 4 5

Environmental 42 45 40 50 50 55 55

1 2 2.5 2 2 2 2 2

2 4 4 4 5 5 6 6

3 3.5 4 3.5 3.5 3.5 4 4

4 3.5 4 3 3 3 3 3

5 2 2 2 2 2 2 2

6 2 2 2 2 2 2 2

7 4 4.5 3.5 5 5 6 6

8 4 4.5 4 5 5 6 6

9 4 4 3.5 5 5 5.5 5.5

10 4 4 3.5 5 5 4.5 4.5

11 4 4.5 4 5 5 6 6

12 3 3 3 4.5 4.5 5 5

13 2 2 2 3 3 3 3


6.3 Description of the scenarios

6.3.1 Base Case

The base case was selected to be consistent with the current works approval that Melbourne Water received from EPA Victoria dated November 2003. In addition to the ammonia reduction, the Works Approval requires Melbourne Water to: • Upgrade the treatment plant to produce ‘Class A’ effluent as defined by the EPA

Victoria Recycling Guidelines through the provision of tertiary filtration and enhanced disinfection

• Extend the existing outfall by a minimum of 2km offshore. The previous works approval submission proposed the technology for the filtration and disinfection to be granular media filtration followed by UV and chloramination disinfection, based on the Class A regulations of the time, but noted the option for the filtration technology to be ultrafiltration following additional investigations during the design phase of the project. The relatively high UV absorbance of the current ETP effluent (essentially a function of the colour), in combination with the changed regulatory guidelines for Class A and pathogen reduction via UV disinfection, reduces the feasibility of UV as a primary disinfectant due to technical, power consumption, and cost considerations, unless the colour is first reduced (e.g. by Ozonation). These factors have eliminated the earlier cost advantage of the Granular Media-UV-Chloramination process train. To produce high quality recycled water in compliance with the current 2006 Australian Guidelines for Recycled Water without significant colour reduction it would be essential to provide some additional pathogen reduction in the filtration process, e.g. through the use of membrane ultrafiltration. Therefore if Melbourne Water were to comply with the directions in the 2003 Works approval for the production of ‘Class A’ water then the filtration technology would need to be ultrafiltration followed by appropriate UV & chloramination disinfection. Due to these changes it is assumed that the ‘base case’ process train would be ultrafiltration followed by UV disinfection and chloramination. An outfall extension 2km offshore is to be included in the works package. Following on from the base case are a range of alternative scenarios which vary in the degree to which they address the impacts in the receiving environment, and fit the broader strategic outlook. The current situation, or ‘do nothing’ scenario has also been


included. All of the options assume the ammonia reduction works have been completed (as these are due for completion in late 2009). The scenarios are as follows:

6.3.2 Scenario 2: No Treatment Upgrade + Fine Screens + Nearshore Outfall

This is the current discharge situation, or ‘Do Nothing’ scenario with only an incremental operational improvement to the current ETP effluent screens to eliminate manual cleaning, making it an automated facility, but capture of litter on the screens will remain similar to current levels. This scenario is obviously the lowest cost but effluent quality remains as per the current and the outfall remains at its current near-shore location. All of the issues explored in the previous sections remain unaltered, and no further opportunities to increase recycling diversions would result.

6.3.3 Scenario 3: No Treatment Upgrade + Fine Screens + Extended Outfall

Extending the outfall 2km offshore removes the visible discharge from near the area of high public use, and it offers the ecosystem on the rocky platforms at Boags Rocks reduced exposure to the effluent. The water quality being discharged will be as per the current, and so any risk reduction for recreational water quality impacts in the marine environment under peak wet weather flow conditions will be limited to that from additional dilution and die-off of pathogens. Amelioration of aesthetic impacts at the current discharge point such as odour and plume visibility caused by foam, dissolved colour and solids is facilitated by increased dilution and relocation offshore. The size of mixing zone for nutrients will be reduced through improved initial dilution offered by the extended outfall diffusers and depth of water where the effluent will be released. The freshwater and toxicity mixing zone will be confined to an area of approximately 560m by 200m immediately above the length of diffusers. The suspended solids load to the marine environment will not be reduced but the relocation of the discharge point will mean that the opportunistic species at the current discharge point will no longer be favoured by this food source.


Effluent quality remains as Class C. The market for recycling this product has been tested and developed for some 30 years and additional growth is not expected. Hence this option does not facilitate increased diversion to further higher value recycled water uses.

6.3.4 Scenario 4: Advanced Tertiary (Ozone/BMF/UV/Chlorine) + Extended Outfall

Based on the results from the Tertiary Technology Trials, this process train will produce very high water quality to address the impacts in the receiving environment and expand the opportunities to recycle. The Ozone-BMF process reduces the foaming potential, colour and odour of the effluent, provides a disinfection step and also a barrier against emerging contaminants. The process train is capable of producing a very high quality effluent that is very low in solids, pathogens, turbidity, colour, oil and grease, foam and odour, assisting with customer acceptance of the water for use in non potable applications such as toilet flushing and clothes washing. The inclusion of the UV disinfection and chlorine makes the water suitable for the most sensitive non-potable recycled water application of fire fighting. The ozone/BMF offers an additional barrier against emerging contaminants of concern. The Ozone-BMF stage of the treatment further improves marine toxicity issues through reduction of peak ammonia levels. The extended outfall provides the relocation and additional dilution to reduce nitrogen and freshwater exposure for the rocky platforms immediately adjacent to the current discharge point. This scenario includes the preferred process train for the upgrade to ETP and the outfall extension as required by the current EPA Victoria works approval. Due to the changes to the requirements for producing ‘Class A’ effluent explored earlier in this document this treatment train is of lower life-cycle cost than the base case treatment train which consists of ultrafiltration, UV disinfection and chloramination.

6.3.5 Scenario 5: Advanced tertiary (Ozone/BMF/UF/Chlorine) + Nearshore Outfall

Scenarios 5-7 are variations on the theme of advanced tertiary treatment and retention of the current outfall arrangements. These scenarios do not incur the costs and impacts associated with outfall construction and seek to deliver their principal benefits through improved treatment, which varies slightly in some aspects as discussed below.


The effluent quality for Scenario 5 is similar to that provided in Scenarios 4 and 6, but with the inclusion of ultrafiltration rather than UV, provides an additional barrier to residual very fine solids (sub 0.05 mm in size) and hence turbidity. This may have marginal benefits for water clarity on occasions and offers the greatest reduction in particulate organic carbon (food source for Boccardia). This process train produces the highest certainty of recycled water pathogen reductions under all flow conditions, of all the shortlisted tertiary process trains, but comes at a price premium of almost $90 million (in net present cost terms) over Scenario 6. The nearshore outfall remains as per the current location at Boags Rocks and mixing zones outcomes will be the same as for scenarios 6 and 7. In retaining the nearshore outfall there still remains a small risk of a discernible surface effect being visible under extreme calm/low mixing conditions, due to the freshwater being lighter than seawater and temporarily floating across the surface before mixing, but this is rare and very unlikely to be considered objectionable. The addition of an ultrafiltration membrane to this scenario increases the capital and operating costs, and energy consumption, over the other advanced tertiary process trains but arguably also offers the best ‘starting point’ for a high end reuse scheme.

6.3.6 Scenario 6: Advanced tertiary (Ozone/BMF/UV/Chlorine) + Nearshore Outfall

The treatment train and hence effluent quality outcomes are as per Scenario 4. This process train is lower cost than Scenario 5, but the water quality produced will still meet the highest non potable uses as specified by the Australian Guidelines for Recycled Water. The treatment process will address the aesthetic issues at the discharge point through reduction of solids, dissolved colour, odour, foam, oil & grease, and litter. The nearshore outfall remains as per the current location at Boags Rocks and mixing zones outcomes will be the same as for scenarios 5 and 7.

6.3.7 Scenario 7: Advanced tertiary (O3/BMF/Chlorine) + Nearshore outfall

This process train is marginally lower in cost than Scenario 6 and will produce a high quality effluent which addresses ammonia toxicity and aesthetic/amenity impacts, however it is unlikely to meet the ‘fit for purpose’ definition for the more stringent recycled water applications, due to the reduced pathogen barriers e.g. for the removal of protozoa. This means that significant flow diversions to recycling with the attendant


benefits for the marine environment are less likely than for scenarios 5 and 6. This process train is also less effective at improving recreational water quality risks. The nearshore outfall remains as per the current location at Boags Rocks and mixing zones outcomes will be the same as for scenarios 5 and 6.

6.4 Discussion and Assessment

6.4.1 Economic Criteria

Net Present Cost

Each scenario was scored based on its Net Present Cost. NPC is calculated based on Melbourne Water’s standard project evaluation model (25 years, post tax real regulated discount rate of 5.8%). Scenario 2 with very low costs is clearly very much better than the base case which incurs high treatment and outfall extension costs. The other scenarios fall between and the scoring is relative to the NPCs. Scenario Treatment Upgrade Outfall NPC ($M) Score

1 Tertiary (UF+UV+Chloramine) extended 692 0

2 screens only current 18 4

3 screens only extended 267 2.5

4 Advanced tertiary (O3+BMF+UV+Cl) extended 584 0.6

5 Advanced tertiary (O3+BMF+UF+Cl) current 427 1.6

6 Advanced tertiary (O3+BMF+UV+Cl) current 339 2.1

7 Advanced tertiary (O3+BMF+Cl) current 311 2.3

Local/Regional Economy - Weighting 2%

What impact does this option have on new business opportunities and local economy? This is considered as proportional to the net present worth of the expenditures over the next 25 years, with scoring adjustment to reflect the degree of imported equipment/value for each scenario. The Base Case involves the construction of a membrane filtration plant, UV disinfection plant and chlorine contact tank at ETP, in addition to the construction of an outfall extension. There is hence significant local construction activity, but there could be equipment purchased from overseas (membranes and particularly UV


disinfection) and specialist equipment used for the outfall construction such as tunnel boring machines and offshore work platforms. Scenario 2 (no treatment upgrade and nearshore outfall) has very little works associated with it (other than replacement of the current final effluent screens). Accordingly this was scored as being much worse than the base case. The other scenarios fall between these. Scenario 3 (no treatment upgrade & extended outfall) has an extended outfall, consistent with the base case however there is no treatment works at ETP. This was scored as being moderately worse than the base case due to the reduced construction requirements. Scenario 4 (Ozone/BMF/UV/Chlorine & extended outfall) has a slightly lower spend than the base case, yet still has some imports associated with the treatment works at ETP. This was scored as being a little worse than the base case. Scenario 5 (Ozone/BMF/UF/Chlorine & nearshore outfall) has complex work at the treatment plant and some imports (e.g. ozone generators and ultrafiltration membranes) but no construction activity at the discharge point. Due to the reduced scope of construction works it was scored slightly worse than scenario 4 and the base case. Scenarios 6 & 7 (advanced treatment and nearshore outfall) there is complex work at ETP, although slightly less for Scenario 7 and no work at the discharge point. For this reason these scenarios were scored as being moderately worse than the base case. Scenario Treatment Upgrade Outfall Score

2 screens only current -4

3 screens only extended -2

4 Advanced tertiary (O3+BMF+UV+Cl) extended -1

5 Advanced tertiary (O3+BMF+UF+Cl) current -1.5

6 Advanced tertiary (O3+BMF+UV+Cl) current -2

7 Advanced tertiary (O3+BMF+Cl) current -2


6.4.2 Social Criteria

Access

What impact does the option have on access to public or private space and the need for land rezoning? Impacts are focussed on construction phase and need for exclusion zones, restricted access, need for construction compounds etc. where public may otherwise freely access. Construction occurring at ETP would be within the existing site in an area the public does not normally expect or require access to. The land is currently zoned for utilities purposes and has been set aside for such activity. This is reflected in the minimal planning permit requirements for the construction at ETP. Access to the area around the outfall during construction was viewed as being important, and likely to be something requiring significant management due to the sensitivity of the location, safety concerns with heavy construction, and community views around the construction of an outfall. Significant aspects of the works from this perspective include: • A cleared and fenced site area for the geotechnical phase and subsequent shaft and

tunnel works. This would require utilisation of a portion of the current golf course as discussed in Appendix 6 for the duration of the project.

• Construction of a site access road suitable for heavy equipment, materials delivery and spoil removal

• Construction of a supply of high voltage power • Use of a jack-up barge for offshore works in both the initial geotechnical phase and

the subsequent marine construction period The base case includes an outfall extension and those scenarios not requiring an outfall extension were hence scored more favourably than those which do as there will be no impact on access to the area surrounding the outfall. All scenarios not requiring an outfall extension were scored as being much better than the base case. Scenario Treatment Upgrade Outfall Score

2 screens only current 3

3 screens only extended 0

4 Advanced tertiary (O3+BMF+UV+Cl) extended 0

5 Advanced tertiary (O3+BMF+UF+Cl) current 3

6 Advanced tertiary (O3+BMF+UV+Cl) current 3

7 Advanced tertiary (O3+BMF+Cl) current 3


Cultural Heritage

What impact does the option have on aboriginal sites of importance or historic buildings, sites and landscapes?. Focuses on land based heritage (water based aspects are covered under SEPP provisions in environmental criteria – weighting split) with relevance particularly around the Coastal Dunes and 'Cups' area and construction proximity to significant sites in National park area. Construction works at ETP for an advanced tertiary treatment facility would occur on a site largely occupied by a carpark, past construction site compound, access roads, sheds, and landscaping dating from the original construction of ETP. The main works area is at least partially disturbed by the original construction of ETP. Portions of the southern extent of the works area where the treated water storage would be located have typically been leased for agricultural purposes for many years. Desktop studies have indicated that no known Aboriginal or European heritage sites are located in the proposed activity area at ETP. Initial field inspections indicate the risk of an Aboriginal archeological site of high significance within the proposed activity area to be low. While the proposed development of the site does not trigger the need for mandatory Cultural Heritage Management Plan (CHMP), a voluntary CHMP would be prepared for the area in question to address any risks of low significance Aboriginal sites occurring in the area and potentially being impacted by the works. The area surrounding the outfall has aboriginal middens in the area and these sites are protected. The outfall alignment is located in an area identified as culturally sensitive. The works required to construct an extended outfall would be defined as high impact activity and hence would invoke a mandatory CHMP. This would apply to both the geotechnical investigations and main construction phases. The site and surrounding area is on the Register of the National Estate. This area applies to the ‘Cup Country’, the Cape Schanck Coastal Park, and the Cape Schanck Landscape area. The relevant planning scheme covering the area includes Public Conservation and Resource Zone (contained with the Mornington Peninsula National Park), Environmental Significance Overlays, and Significant Landscape Overlays. The scenarios not requiring an outfall extension were scored as being a little better than the base case because there will be no construction activity around Boags Rocks. Given the factors outlined in the Environmental, Planning and Cultural Heritage Investigations sections (Appendix A) of Appendix 6 it could be reasonably argued that these scenarios would be ‘moderately’ better than the base case. However the


construction method and site location were selected to reduce risks, and work in the area would have a range of controls to reduce the risk of disturbing aboriginal artefacts. Landscape impacts would be limited to during the geotechnical and construction phases of the project. Hence the scoring adopted is as follows: Scenario Treatment Upgrade Outfall Score







Community Expectations on Treatment, Safety & Amenity

How does the option address the affected community perceptions and preferences with regard to acceptable wastewater treatment standard and effluent quality & enjoyable use of the area as impacted by the discharge. Considers community perceptions & preferences (some of which may not be purely scientific) around the use of the environment. Also considers community uses such as fishing, horse riding, and general public use of the impacted area. Assessment against this social criteria is influenced and informed by community perceptions, values and preferences. Where there was potential for overlap with some aspects of particular environmental criteria, the weighting was split and the relevant environmental criteria were focussed more tightly on the specifics of measurable marine outcomes associated with each scenario. This criteria addresses the community perceptions of the aesthetic impacts, acceptability of the effluent quality and allowing for the safe and enjoyable use of the area surrounding the discharge at Boags Rocks. It takes into consideration the perceived health risks in addition to the aesthetic enjoyment of the environment. Swimmers and surfers at Gunnamatta beach have long complained of skin, ear, throat and other respiratory infections following swimming and surfing at Gunnamatta and often link the infection to the Boags Rocks outfall. As discussed in Section 2.4.7, the beach classification under the NH&MRC guidelines suggests health risk to recreational users under normal conditions is comparable with other clean beaches, yet there is still a strong and persistent view from recreational users of the area that the current discharge makes them sick, and the effluent quality is unsuitable for supporting their safe and enjoyable use of the water.


The aesthetics of the discharge strongly influence perceptions of the environmental quality in the area. The interlinking of some of the contributing factors e.g. odour being attributed to foam and plume visibility observations illustrates the significance of these factors. The general public are less likely to use a beach that is perceived to be ‘dirty’ or is obviously impacted upon by treated effluent, and with the current aesthetic issues associated with the outfall the general public may be less inclined to use the beach for recreational activities. The clear message from consultation programs has been the current effluent quality does not meet the expectations of the local stakeholder community. Base Case: (tertiary filtration and outfall extension). The base case should address the perceived pathogen risks through filtration and disinfection and extending the outfall. Removing the discharge from the area used for recreation and filtering it should address marine and beach aesthetic perceptions at the current discharge point, however it does not go as far as the advanced tertiary scenarios in meeting community perceptions of the inherent acceptability of the treatment standard and the quality of effluent due to it’s residual colour and odour. Scenario 2: (No treatment upgrade and nearshore outfall) was scored as being very much worse than the base case, and relative to the other scenarios was scored as the least preferred scenario. This does nothing to address the social concerns with public health and amenity for the receiving amenity or producing an acceptable effluent quality. Extensive community consultation has consistently indicated that the current treatment standards are not satisfactory to those affected. Scenario 3: (No treatment upgrade and extended outfall) Although this scenario removes the point of discharge 2km offshore and well away from recreational users, it will not address the perceived issues of the inherent quality shortcomings of the current effluent discharge and may increase concerns in certain quarters of an ‘out of sight out of mind’ approach to management of the discharge. Extensive community consultation has consistently indicated that the current treatment standards are not satisfactory to those affected. This scenario was scored as being moderately worse than the base case in addressing social concerns, as it only offers relocation of the discharge and is not combined with a commitment to improve quality. It can be considered moderately better than Scenario 2 as it does significantly reduce the risk of colour and odour impacts at the shoreline. Scenario 4: (Ozone/BMF/UV/Chlorine & extended outfall) By treating the water to a very high level, and by removing the discharge from the immediate area used for recreation this scenario scored highest and a little better than the base case, as it also


deals with community perceptions around of the inherent acceptability of the effluent quality due to it’s residual colour and odour. Relative to the other scenarios this offers the lowest residual risk of impacts at the shoreline. Scenario 5: (Ozone/BMF/UF/Chlorine & nearshore outfall). This was scored 0.5 higher than the base case as this scenario offers the highest level of treatment, which consultation has indicated is preferred to an outfall extension as a means of reducing concerns. It could be argued that this could be scored higher due to the quality of the water being produced and a lack of ‘out of sight out of mind’ concerns associated with relocating the discharge. Scenario 6: (Ozone/BMF/UV/Chlorine & nearshore outfall). This was scored as equivalent to the base case as it will address the perceptions of public health risks under all conditions and significantly improve the aesthetics in the area surrounding Boags Rocks through reduction of foam, odour, colour, litter, and fat balls. It also deals with community perceptions around of the inherent acceptability of the effluent quality due to residual colour and odour and does not lead to ‘out of sight out of mind’ concerns associated with relocating the discharge. Relative to the other advanced tertiary scenarios, it was scored slightly lower than scenario 5 as UF offers a higher degree of certainty in turbidity reduction to the lowest possible levels, and scored slightly higher than scenario 7 as it has an additional disinfection barrier and a lower pathogen risk based on QMRA. Scenario 7: (Ozone/BMF/Chlorine & nearshore outfall). Although this offers similar aesthetic outcomes as scenario 6, scenario 7 doesn’t offer the same level of disinfection barriers as scenarios 4, 5, and 6 and the lack of ‘Class A’ classification has potential to undermine community confidence in public health outcomes, particularly under peak wet weather flow conditions. Hence the scoring adopted is as follows: Scenario Treatment Upgrade Outfall Score




5 Advanced tertiary (O3+BMF+UF+Cl) current 0.5


7 Advanced tertiary (O3+BMF+Cl) current -0.5


Strategic Community Benefit to Future Recycling

Contribution to cost effective recycling development (removal or creation of barriers). Community appetite for cost effective recycling developments is clear, and if an option provides benefits for the establishment of recycling schemes in the future then it is seen as a positive outcome. The degree of treatment offered may assist in the development of future uses. The principal drivers for upgrading treatment at ETP in the short term are outcomes for the receiving environment, but the additional benefit to recycling development also accrues. The addition of tertiary or advanced tertiary treatment makes the water much more attractive for use in recycled water schemes and increases the range of potential applications. Without the inclusion of tertiary or advanced tertiary treatment, the market for recycling this product will remain largely as it has for some 30 years. The customer research results discussed earlier in Section 2.6.8 show a clear benefit to potential customer take-up of recycled water for more sensitive uses if the colour is reduced, as would be the case for the scenarios which include advanced tertiary. The advanced tertiary process also offers an additional barrier to emerging micro-contaminants that are frequently cited as potential ‘perception barriers’ to increasing recycling in more sensitive applications. Improving the quality of the water removes an economic barrier for the development of recycled water schemes. Any proponent of a recycled water scheme can invest more in recycled water infrastructure to reach a greater number of customers or additional value adding treatment (such as reverse osmosis) if necessary, rather than having to also expend capital to improve quality from the current ‘Class C’. The scenarios which include upgrading the plant for environmental benefits offer the potential for the most cost effective wholesale supply of ‘Class A’ water in Melbourne. Including an outfall in a scenario was not viewed as being a socially positive attribute to future recycling, in that some may perceive it as entrenching disposal or becoming a stranded asset over the longer term as larger recycled water schemes developed and diverted the flow from the outfall, or the funds employed in constructing an outfall extension reducing the community’s capacity for funding recycling schemes.


Base Case: (tertiary filtration & outfall extension). The treatment provides for Class A effluent, but does not remove colour or odour from the effluent and doesn’t provide an additional barrier to microcontaminants. The inclusion of an extended outfall potentially impacts on recycling as discussed above. Scenario 2: (no treatment upgrade and nearshore outfall). This was scored as being moderately worse than the base case. While it maximises ‘preservation’ of the community’s potential for funding recycling schemes by not expending funds on an outfall extension, it does not offer the ‘free kick’ to recycling that scenarios including a treatment upgrade provide. Scenario 3: (no treatment upgrade and extended outfall). This was scored as being much worse than the base case. There is no treatment upgrade to facilitate recycling, and the construction of the outfall reinforces disposal of the effluent rather than turning it into a resource. Scenario 4: (Ozone/BMF/UV/Chlorine & outfall extension). The level of treatment that this scenario offers is better than the base case in that colour and odour will also be reduced, making the product more acceptable by the community for recycled water applications. The inclusion of the outfall extension incurs the negative aspects and perceptions discussed above. Scenario 5: (Ozone/BMF/UF/Chlorine & nearshore outfall). This is the highest level of treatment offered and so does the best to facilitate future recycling. It removes the colour and odour from the effluent, attributes likely to assist with customer acceptability There is no outfall extension so the aspects discussed above are absent. Scenario 6: (Ozone/BMF/UV/Chlorine & nearshore outfall). Similar to scenario 5 this produces a very high quality of recycled water without the inclusion of an extended outfall. It was scored slightly lower than scenario 5 to differentiate the certainty of water quality outcomes and customer perceptions between the UF and UV processes.. Scenario 7: (Ozone/BMF/Chlorine & nearshore outfall). This was scored very slightly higher than the base case as it offers reduced sunk cost (no outfall extension) and addresses the product water colour and odour and includes the same micro-contaminant barrier as scenarios 4, 5, and 6. It scores lower than scenarios 4, 5 & 6 as while it offers a very good starting point for future recycling, there will need to be an additional pathogen barrier added to ensure it is ‘fit for purpose’ for the more sensitive uses (which can be added more cost effectively than colour/odour removal could be added to the base case to improve customer acceptance).


Scenario Treatment Upgrade Outfall Score 2 screens only current -2


4 Advanced tertiary (O3+BMF+UV+Cl) extended 1.0



7 Advanced tertiary (O3+BMF+Cl) current 0.5

Consistency with Policy & Community Attitudes

Does the option fit with community attitudes to water resources and water cycle management, Government Policy (CRSWS, OWOF, Statement of Obligations, etc.) and Melbourne Water Policy?. Extensive community consultation was undertaken during the preparation of the works approval in 2001 and was followed up with public hearings conducted by EPAV. Results from the community showed they were in favour of upgrading the treatment plant to produce high quality water that could be used in a range of non potable applications. They were generally not supportive of an extension to the outfall as they saw it as simply ‘moving the problem to another location’. The community views are discussed in greater detail in Section 3.8. Further consultation has been undertaken through the ETP Community Liaison Committee (ETP CLC) over the past few years. The general feedback can be paraphrased as ‘our views on the upgrade of the treatment plant have not changed, ETP should be upgraded and the water used as a resource’. The most recent feedback from the ETP CLC was received on 19th February 2009. The CLC noted the work that Melbourne Water has undertaken over the past 12 months on the tertiary technology trials and were supportive of an upgrade to ETP that included advanced tertiary treatment. In June 2007 - Our Water Our Future – The Next Stage of the Governments Water Plan, restated the commitment to the project. “The Government is committed to upgrading the ETP to tertiary standard, a level where a wide variety of reuse is possible. The upgrade of the ETP will be completed during 2012.” The September 2008 Victorian Government submission to the ENRC parliamentary enquiry reiterated the commitment.


Both Our Water Our Future, and it’s forerunner the Central Region Sustainable Water Strategy, include recycled water as an important part of a diversified portfolio of fit for purpose water resources for Melbourne and Victoria. The upgrade of the ETP to produce a high quality recycled water product is included in both these strategies consistent with the Victorian Government announcement in October 2006 that the ETP upgrade to include tertiary treatment would be completed in 2012. Requirements of statutory environmental policy as set out in the State Environment Protection Policy Waters of Victoria are addressed separately in detail in the Environmental criteria of the TBL assessment. The options that include higher levels of treatment are seen to be more favourable by the community. The options that provide a level of treatment that both protects the environment and enables greater recycling are more consistent with the policy aspects outlined above than those that include less treatment. The scoring of this criteria is as follows: Base Case: This provides a level of treatment which would be consistent with policy and community attitudes. The extension of the outfall is not consistent with community views. Scenario 2: (no treatment upgrade and nearshore outfall). This is not consistent with policy or community attitudes and was scored as being very much worse than the base case and all of the other scenarios. Scenario 3: (no treatment upgrade and extended outfall). This was also scored as being very much worse than the base case and as there is no treatment included in the scenario was the same as scenario 2. Scenario 4: (Ozone/BMF/UV/Chlorine & extended outfall). This scenario offers a higher level of treatment than the base case and hence scores slightly better. Upgrading the treatment to address marine impacts and produce a high quality recycled water product is consistent with community views and policy. Scenario 5: (Ozone/BMF/UF/Chlorine & nearshore outfall). This is consistent with community views on the upgrade for ETP and is also consistent with policy. This was scored as being much better than the base case due to the higher level of treatment and avoidance of outfall extension (which past consultation indicates was opposed). Scenario 6: (Ozone/BMF/UV/Chlorine & nearshore outfall). As per scenario 5.


Scenario 7: (Ozone/BMF/Chlorine & nearshore outfall). Similar to scenarios 5 and 6 however the lesser treatment level and lack of ‘Class A’ reduced the score accordingly. Scenario Treatment Upgrade Outfall Score







6.4.3 Environmental Criteria

Beneficial Use – Aquatic Ecosystems

Does the option address the protection of largely unmodified environments.(i.e. open coast segment). Area should be capable of supporting high levels of environmental quality after the implementation of practicable environment improvement measures. What is the opportunity to return to largely unmodified ecosystem. Consider both the current situation and future volume of discharge. Consider nutrients, DO, water clarity (TSS, colour, turbidity). The current level of treatment coupled with a nearshore outfall will continue to have a detrimental impact on the marine environment at Boags Rocks. The suspended solids concentration will be as per current levels which do not assist with reducing the food source for the Boccardia, which has colonised the rocky platforms due to the abundance of food available in the effluent. Doing nothing to improve the treatment, (beyond the current ammonia reduction changes in the secondary treatment area) will not reduce nutrients, suspended solids or water clarity or assist with reducing flows and loads discharged through diversion of the effluent to recycling applications. Continuation with the current situation, has seen ammonia concentrations in the effluent reduced and some evidence of a return of the Hormisira Banksii to Fingals Beach. Further surveys of the surrounding environment will be required to confirm this return but the early indications are positive. Given that the Hormosira is the most sensitive species to ammonia toxicity, the reduction of the ammonia in the effluent, and the return at Fingals Beach suggest that further ammonia reduction may enhance


the chances of Hormorsira recovery at the Boags Rocks area platforms, depending on the significance of residual nutrient influence from nitrogen. It is possible that further reducing the ammonia and suspended solids through an advanced tertiary treatment process will allow the Hormisira to recolonise the rocky platforms as it is less sensitive to freshwater and removing the particulate organic carbon removes the food for the Boccardia. Indications and results from other long outfalls around Australia and the world, combined with the observation of recovery at Fingals where effluent exposure is similar to what an outfall extension would achieve, suggest that relocation of the discharge point away from Boags Rocks will offer the best chance of allowing the ecosystem on this rocky platform area immediately at the discharge point to recover. The scoring of the scenarios is set out below: Base Case: (tertiary filtration & extended outfall) this removes the discharge from the rocky platform at Boags Rocks so would be expected to allow the ecosystem to recover over time. Scenario 2: (no treatment upgrade, nearshore outfall). This scored very much worse than the base case due to no improvements in water quality and the discharge continuing onto the rocky platforms. The quality of effluent would be unlikely to reduce the volume of discharge through major recycling schemes. Scenario 3: (no treatment upgrade, extended outfall). Scored as being a little worse than the base case. Its much better than scenario 2 as the discharge point is relocated away from the rocky platforms and also allows greater initial dilution via the extended outfall. The quality of effluent is not being upgraded so loads to the environment are unchanged and it would offer no ability to reduce the volume and loads discharged via recycled water schemes. Scenario 4: (Ozone/BMF/UV/Chlorine & extended outfall). Scored slightly better than the base case due to the higher level of treatment meaning there may be a greater opportunity to divert flow to recycled water schemes, and reduced ammonia and micro-contaminant loads. As with the base case, the extended outfall moves the discharge point and increases initial dilution allowing the Boags Rocks intertidal platform ecosystems to recover. Scenario 5: (Ozone/BMF/UF/Chlorine & nearshore outfall). This is the highest level of treatment, and with the inclusion of the UF membrane reduces the smallest


suspended solids to lower levels than scenarios 6 and 7. The ammonia will be consistently reduced to very low levels to protect the most ammonia sensitive species. There is a good chance of diversion of flow to recycled water schemes due to the quality of the effluent produced. This scored as a little worse than the base case due to the discharge location. Scenario 6: (Ozone/BMF/UV/Chlorine & nearshore outfall). Scored slightly lower than scenario 5 as although the water quality will be very good there is very slightly higher turbidity from this treatment train compared with scenario 5 which includes membrane filtration downstream of the biological media filters. This scored lower than the base case due to the discharge location, meaning lower dilution levels at the shoreline adjacent to the discharge point. Scenario 7: (Ozone/BMF/Chlorine & nearshore outfall). As per Scenario 6. Scenario Treatment Upgrade Outfall Score




5 Advanced tertiary (O3+BMF+UF+Cl) current -1

6 Advanced tertiary (O3+BMF+UV+Cl) current -1.5


Beneficial Use – Recreation

Does the option make the water suitable for use as both primary and secondary contact? Consider the pathogen levels in the treated effluent and QMRA results for Boags Rocks. This clause requires that the water be suitable for primary and secondary recreation. This includes activities such as swimming, surfing and boating. The receiving environment is currently ranked as ‘Good’ to ‘Very Good’ by the NHMRC guidelines all year round, however the NHMRC guidelines recommend a different approach be undertaken to understand the risks associated with unusual operational conditions such as peak wet weather events. To understand the risks associated with the operational changes under peak wet weather flow conditions, a Quantitative Microbial Risk (QMRA) Assessment was undertaken.


The QMRA showed that scenarios 2, 3 & 7 are less effective at protecting recreational users under peak wet weather flow conditions. The scenarios were scored as follows: Base Case: this includes treatment to produce ‘Class A’ effluent and an outfall extension which will increase the initial dilution, making the water suitable for recreational use under all conditions. Scenario 2: (no treatment upgrade & nearshore outfall) was scored as being much worse than the base case as there will be no change to current risk level under peak wet weather conditions, however under normal operating conditions water quality is rated as very good. Scenario 3: (no treatment upgrade & extended outfall) was scored as being slightly worse than the base case. The extended outfall increases the initial dilution in the receiving environment and takes the discharge away from the area used for recreation, however it does not offer the level of pathogen reduction as included in the base case and there is still an increased risk to recreational users under peak wet weather conditions. Scenario 4: (Ozone/BMF/UV/Chlorine & extended outfall) was scored as being equivalent to the base case as there is a very high level of treatment which will address any risk to recreational users. Scenario 5: (Ozone /BMF/UF/Chlorine & nearshore outfall) was also scored as equivalent to the base case due to the level of treatment being provided which will reduce the risk under all conditions to recreational users of the environment. Scenario 6: (Ozone /BMF/UF/Chlorine & nearshore outfall) as per Scenario 5 Scenario 7: (advanced treatment – without UF or UV & nearshore outfall) was scored as being a little worse than the base case. This treatment train does not have multiple barriers for protozoa and hence does not provide the same degree of risk reduction to recreational users as scenarios 4, 5 and 6. Scenario Treatment Upgrade Outfall Score








Beneficial Use – Water Based Recreation (Aesthetics)

Does the scenario address the aesthetic issues in the receiving environment? Consider solids, colour, odour, litter, foam, oil & grease etc. Aesthetic enjoyment is a beneficial use to be protected under the SEPP (WOV) and specific provisions apply which include areas within mixing zones. The aesthetic impacts that have been observed at the Boags Rocks outfall include plume visibility and water clarity, odour in the vicinity of the outfall, litter on Gunnamatta and St Andrews beaches in the form of cotton bud sticks, small plastics and sanitary gauze, foam which is persistent in the environment, and can be brown and odourous, and small oil & grease particles or ‘fatballs’ often found on the beaches. The Advanced Tertiary Treatment process that includes ozone and biological media filtration will address the plume visibility caused by solids, turbidity (by the inclusion of a filtration process) and dissolved colour (via oxidation with ozone). Any filtration process will also remove litter, biological foam and oil & grease, from the effluent. The Advanced Tertiary Treatment process also further reduces the residual foam formation potential through reduction of surfactant like effects to essentially that of tap water. The current treatment plant, (with upgraded screens) is likely to only remove marginally more litter than currently occurs. No screens are capable of capturing 100% of litter. The outfall extension will address the aesthetic issues of plume visibility and odour by the relocation of the discharge point where it can not be observed from the shoreline and increasing the initial dilution to. The outfall extension without additional treatment may be less successful at fully addressing the aesthetic impacts of litter, foam and oil & grease. Base case- (tertiary filtration and outfall extension). Treatment provides a barrier against litter, oil and grease and foam. Plume visibility and odour will be addressed by relocating the discharge point offshore. During periods of low dilution there may still be a risk of plume visibility at the point of discharge. This however would only be applicable for an observer close to that location (not at the shoreline).


Scenario 2: (No treatment upgrade and nearshore outfall) This does not address the aesthetic issues associated with the discharge and was scored as being much worse than the base case. Scenario 3: (No treatment upgrade and extended outfall). This will improve the aesthetics from the shoreline as the outfall will provide adequate initial dilution to address most issues. The aesthetics are being addressed through relocation and dilution to protect the beneficial use close to the shoreline. There is still a residual risk of litter and the potential for oil & grease (fatballs) and foam washing up on the shore around Gunnamatta and St Andrews beaches. This scored a little worse than the base case due to these factors. Scenario 4: (Ozone/BMF/UV/Chlorine & outfall extension). This option provides a very high level of treatment and will address all of the aesthetic issues via treatment. The outfall extension would further reinforce this outcome. As this scenario offers the greatest level of protection of the beneficial use through the inclusion of treatment and outfall extension it was scored as a little better than the base case. Scenario 5: (Ozone/BMF/UF/Chlorine & nearshore outfall). This option will address all of the aesthetic issues via treatment. The ultrafiltration process will remove all solids and turbidity and Ozone-BMF the dissolved colour and odour. The only residual risk of plume discernibility will be during rare periods of low initial dilution where the buoyant effect of the freshwater ‘floating’ could potentially be slightly apparent, but is very unlikely to be considered objectionable. This option was scored very slightly worse than the base case. Scenario 6: (Ozone/BMF/UV/Chlorine & nearshore outfall) will be essentially equivalent to Scenario 5 with regard to aesthetics. In theory there will be a marginal difference in the residual turbidity when compared with Scenario 5 (although this is unlikely to be detectable in the receiving environment). To recognise this difference this was scored slightly lower than scenario 5. Scenario 7: (Ozone/BMF/Chlorine & nearshore outfall) will be equivalent to Scenario 6 with regard to aesthetics to the aesthetics outcomes. Scenario Treatment Upgrade Outfall Score








Beneficial Use – Cultural and Spiritual Values

Does the scenario consider the cultural and spiritual values held by indigenous communities, rural & urban and local community groups - (e.g. surfers, water based festivals etc). Considers the marine environment more so than the surrounding coastal environment which was addressed in the social criteria. By not providing any additional treatment, the water based surfing festivals will continue to be impacted by the effluent discharge at its current quality. This is a beneficial use for protection in the SEPP, and has been treated separately to “Cultural Heritage” in the Social category which was focussed on the land based aspects such as the aboriginal middens in the area behind the dunes. Base Case: (tertiary filtration & outfall extension) The effluent discharge is moved away from the nearshore area that would be used for cultural and spiritual values. Scenario 2: (no treatment upgrade & nearshore outfall) this option will not change the current situation and was scored much worse than the base case. This scenario offers no change to the cultural and spiritual values of the marine environment. Scenario 3: (no treatment upgrade & extended outfall) this option will still have an impact on the coastal areas, particularly during construction, but will have a longer term benefit to the receiving environment. It was scored moderately worse than the base case (due to the lack of effluent quality improvement), yet slightly better than scenario 2. Scenario 4: (Ozone/BMF/UV/Chlorine & extended outfall) this option was seen to be equivalent to the base case- both options provide treatment and an extended outfall which will improve the local environment in the long term but will experience some disruption in the short term. Scenarios 5, 6 & 7: (advanced tertiary treatment and nearshore outfall) these were scored equivalent to the base case due to the level of treatment that will be provided which will address the cultural use issues however there is no impact from construction of the outfall in the short term. Scenario Treatment Upgrade Outfall Score








Beneficial Use – Water for Aquaculture

Does the scenario make the water suitable for production of fish, crustacea and molluscs for human consumption. Consider microcontaminants and how the option will deal with this in reducing bioaccumulation risks. Consider the pathogen levels in the treated effluent. The beneficial uses included in this section are a combination of 2 protected uses for the coastal segment, however the scoring in the MCA were very similar and they have been included together as 1 criteria. These uses are primarily protected by ensuring the water that they are growing in is not impacted by human pathogens. The SEPP refers to E.Coli. and Enterococci, but Melbourne Water has also considered the full suite of pathogens that are potentially in treated effluent. The options that include a treatment upgrade will offer a high level of protection to this beneficial use. Similar to the water being suitable for recreation, treatment will reduce pathogen numbers by an additional 4-5 log, whereas the outfall extension without treatment does not reduce the load and relies solely on increasing dilution and die-off during marine transport and hence is much less effective. An additional benefit of including the Ozone-BMF process within the treatment train is the provision of an additional barrier to micro-pollutants. Micro-pollutants of natural and anthropogenic origin are present in sewage and to a lesser extent in treated sewage effluents. The current effluent poses no significant impacts on fish, crustacea and molluscs for human consumption based on the parameters such as trace metals measured in testing of marine species from the area. It is not however possible to analyse for all the micropolluants potentially present in effluent and fully predict environmental impacts.


however it scored lowest relative to the base case and other scenarios as it does nothing to. Base Case: (tertiary filtration & outfall extension). The base case provides both treatment and an outfall extension, and although it will address the residual risk of pathogens, the form of tertiary treatment does not offer a barrier against dissolved micro contaminants like the advanced treatment process trains do. Scenario 2: (no treatment upgrade and nearshore outfall). This option ranked lowest in that it does nothing to further reduce the risk from emerging contaminants of concern or pathogens. Given that there is not currently believed to be a significant issue with the existing discharge, the scenario was scored as being only moderately worse than the base case. Scenario 3: (no treatment upgrade and extended outfall). This option relocates the discharge ~2km offshore, increasing the initial dilution. There is no additional treatment barrier and any risk is being addressed through dilution. This was scored as being a little worse than the base case because of the lack of treatment to remove even the solids associated contaminants through filtration. Scenario 4: (Ozone/BMF/UV/Chlorine & extended outfall) the advanced treatment offers a barrier against pathogens and also against micro contaminants and hence is an improvement on the base case. Scenarios 5, 6 & 7: (advanced tertiary treatment and nearshore outfall) the advanced treatment process offers an effective barrier against pathogens and micro contaminants, which is an advantage over the base case, however the outfall remains nearshore so the options were scored as being only slightly better than the base case. Scenario Treatment Upgrade Outfall Score





6 Advanced tertiary (O3+BMF+UV+Cl) current 0.5



SEPP Clause 27 – Management of discharges to surface waters

Ensure effective wastewater management practices are undertaken to minimise environmental risks to beneficial uses of water environments. Does the scenario consider the use of 'best practice' and appropriate combination of technology & process to reduce the impacts. Using best practice technologies and processes to achieve the best outcome for the environment. Although the use of secondary treatment and nearshore outfall could once have been seen as best practice compared to other treatment plants both within Australia and around the world, there is a general trend of increasing treatment levels prior to discharge to the receiving environment. Back in the 1970’s ETP was seen as a leader in the level of treatment that was provided (secondary treatment) prior to discharge to the environment, and then the effluent was discharged to Bass Strait rather than Port Phillip Bay (as was originally considered in the 1960s). In recent years examples have emerged where significant shoreline discharges near areas of high community value have moved to some form of tertiary treatment, such as Cronulla in NSW and Mangere in Auckland, NZ. Moving forward to 2009, community expectations around a more sustainable approach to water cycle management are heightened. Combined with extended drought and the reality of climate change, there is now a strong driver and preferred policy direction to develop over time a diversified portfolio of fit for purpose water resources. Although driven largely by improving the marine environment, an advanced tertiary upgrade to ETP offers a significant fillip to this direction by making a high quality product available at low cost, and removing a barrier to recycled water scheme developments that would have otherwise been held back by additional treatment costs. Class A recycled water from ETP offers a less climate dependant water resource suitable for a broad range of non potable uses. Removing the colour and odour from the product water also enhances customer acceptance and potential uptake. Outfalls have been used for many years to dispose of wastewater and can be of varying lengths depending on the level of treatment provided by the wastewater treatment plant and the sensitivity of the receiving environment. Many of the original extended outfalls around the world have been progressively moving to increased levels of treatment over the past 20 years (primary to secondary to inclusion of disinfection etc).


The very high level of treatment proposed in Scenarios 4, 5, and 6 would clearly represent best practice for large scale treatment for discharge to the open marine environment. Providing a very high level of treatment and an extended outfall would be well beyond best practice, whereas upgrading the treatment to address the current impacts with a nearshore discharge could be considered as best practice for the ETP and Boags Rocks situation as it provides protection to the beneficial uses as required by the SEPP in the receiving environment, and it also aligns with the strategic policy direction of increasing reliance on a diversified, less climate dependent water resource portfolio. An extensive program of environmental monitoring and investigation, and trialling of innovative treatment technology combinations has been used to enable selection of best practice measures. The scenarios were scored as follows: Base Case: (tertiary filtration & outfall extension). It could be argued that this is best practice as the water is treated to a very high standard microbiologically and it will be suitable for a wide range non potable uses, however there will still be colour and odour associated with the product water impacting on customer acceptance. The outfall extension addresses those aesthetics issues in the environment. The treatment technology trials have demonstrated that the tertiary process as included in this scenario is not the optimum approach for ETP effluent, and the advanced tertiary process offers a superior benefit/cost equation and hence is better practice. Scenario 2: (no treatment upgrade & nearshore outfall). This was scored as being very much worse than the base case as it is no longer considered best practice to have secondary treated effluent discharging via a nearshore outfall. Scenario 3: (no treatment upgrade & extended outfall). This was scored as being moderately worse than the base case. The extended outfall removes the discharge from the rocky platforms and this combined with the current secondary treatment could be considered as common historical practice. Without a treatment upgrade, based on the current strategic and water resources environment in Melbourne this could not be considered as best practice. Scenario 4: (Ozone/BMF/UV/Chlorine & outfall extension). This scenario is beyond best practice due to the combination of the advanced treatment and outfall extension. The advanced treatment will address current impacts in the receiving environment, with the exception of a very small mixing zone, which the extended outfall would then


relocate. This was scored as a little better than the base case due to the level of treatment provided, including a barrier to emerging contaminant concerns and the increased customer acceptance of low colour/odour product water. Scenario 5: (Ozone/BMF/UF/Chlorine & nearshore outfall). This scored slightly higher than the base case. The treatment related benefits are as per Scenario 4 plus the ultrafiltration offers an absolute barrier to residual turbidity. The level of treatment being provided would be considered to be slightly better than best practice (the form of tertiary treatment is significantly more advanced than that offered at Cronulla or Mangere for example, and offers a future proof platform for recycling development). Scenario 6: (Ozone/BMF/UV/Chlorine & nearshore outfall). This scenario was scored as being equivalent to the base case as the improved treatment and better alignment with future directions offsets the omission of the discharge point relocation. The level of treatment being provided would be considered at least best practice (the form of tertiary treatment is more advanced than that offered at Cronulla or Mangere for example, and offers a future proof platform for recycling development). Scenario 7: (Ozone/BMF/Chlorine & nearshore outfall). This scenario is very similar to scenario 6 but offers less pathogen barriers and is less effective at providing for the more sensitive Class A type applications. Scenario Treatment Upgrade Outfall Score







SEPP Clause 27 – Management of discharges to surface waters (part 2)

Ensure effective wastewater management practices are undertaken to minimise environmental risks to aquatic ecology. Does the option produce a discharge that results in lethal effects to the aquatic ecology? Are there chronic effects likely outside the mixing zone? Consider the discharge arrangements, the quality of the effluent, potential for further reduction over time. If discharge contains a non persistent


substance that degrades within a declared mixing zone (e.g. freshwater) then a mixing zone may be approved. Consider both peak and average toxicity. Effluent toxicity testing with a range of species representative of the most sensitive flora and fauna associated with Boags Rocks has been undertaken routinely since 1997 by CSIRO. The outcomes of the studies have been used to determine safe dilution factors. Discussion of these findings is included in earlier sections of this report and the Appendices. The principal role of ammonia in the effluent toxicity has been highlighted, particularly for H. Banksii. When ammonia is low, safe dilution for H. Banksii is 4:1 indicating it is relatively insensitive to freshwater. The most sensitive species for freshwater is scallop larvae with a safe dilution of 20:1 (when ammonia is reduced). Ammonia and freshwater effects are able to account for the observed toxicity response in most but not all tests. Where ammonia concentrations are low, safe effluent dilutions to protect marine species of 20:1 have been derived based on the testing. The scenarios were scored as follows: Base Case: (tertiary filtration & outfall extension) The combination of current ammonia reduction works (to annual median of 5 and 90th percentile of 10 mg/L) and the outfall extension will ensure ammonia toxicity impacts are addressed. The form of tertiary treatment in this scenario does not offer any further potential reduction of other toxicant loads, but the initial dilution protects ecology outside the zone of initial dilution. Scenario 2: (no treatment upgrade & nearshore outfall). The current ammonia reduction works have successfully reduced ammonia levels, with benefits for the marine environment, but this scenario offers no further improvement in ammonia levels and no further exposure reduction via increased dilution levels or relocation of the discharge and hence is scored moderately worse than the base case. Scenario 3: (no treatment upgrade & extended outfall). The increased dilution offered by the outfall extension will assist with the current impacts to the aquatic ecology. The lack of additional treatment steps means that there is no reduction in suspended solids or further barrier to other potential toxicants, and there is no attempt to facilitate increased diversions of flow and loads over time to increase benefits. Scenario 4: (Ozone/BMF/UV/Chlorine & extended outfall). Given the high level of treatment with very low ammonia levels and additional barrier to other toxicants, and improved customer acceptance of the water quality increasing potential flow


diversions, combined with the effects of the extended outfall, this was scored as being slightly better than the base case. Scenario 5, 6 & 7: (advanced tertiary treatment & nearshore outfall). These scenarios were all scored as being slightly worse than the base case. The advanced treatment reduces ammonia down to very low levels which subsequently lowers the requirements for initial dilution in the receiving environment that would otherwise be required. They also offer an additional contaminant/toxicant barrier. Effects outside the small mixing zone based on safe dilution levels will be absent. However as these scenarios don’t include an extended outfall to reduce freshwater and nutrient exposure at the Boags Rocks intertidal platforms, they were scored lower than scenarios 3, 4 and the base case. Scenario Treatment Upgrade Outfall Score





6 Advanced tertiary (O3+BMF+UV+Cl) current -0.5


SEPP Clause 29 – Existing wastewater discharges

Does the option maximise wastewater avoidance and re-use opportunities? Consider how the options will facilitate this to help to reduce the size of the mixing zone in the future. SEPP requires 'continuous improvement' to shrink mixing zone size. The scenarios which include an upgrade to the treatment process at ETP will all assist in maximising re-use opportunities and avoiding disposal. Those scenarios offering treatment and the opportunity to reduce the volume of effluent being discharged have been viewed more favourably. It could be argued that the sunk cost associated with inclusion of an outfall would be more likely to entrench disposal and lessen the likelihood of reuse. Reducing the volume of effluent being discharged to the marine environment via diversion to recycled water applications will contribute to reducing loads to the marine environment and the size of the mixing zones.


Base Case: (tertiary filtration and extended outfall). This scenario produces ‘Class A’ water suitable for a wide range of non potable applications, however there will still be colour and odour associated with the product. This may influence its acceptability for certain applications such as third pipe schemes. Scenario 2: (no treatment upgrade & nearshore outfall). This scored much worse than the base case as there is no means to further facilitate recycling or further reduce the size of the mixing zones, either through improved treatment, diversion to recycling or increased dilution via an extended outfall. Scenario 3: (no treatment upgrade & extended outfall). This scored much worse than the base case. There is no additional treatment being provided to facilitate recycling. This scenario is focused on ‘disposal’ which is inconsistent with the intent of the SEPP, and may entrench this approach to the dis-benefit of reuse opportunities. Scenario 4: (Ozone/BMF/UV/Chlorine & extended outfall). This scored as being a little better than the base case. The level of treatment being provided will assist in maximising opportunities to reuse and avoid disposal. It could be argued that the sunk cost associated with inclusion of an outfall would be more likely to entrench disposal and lessen the driver for reuse. Alternatively, if recycling opportunities are fully realised in the long term, the outfall extension may be underutilised. Scenario 5: (Ozone/BMF/UF/Chlorine & nearshore outfall). Given this treatment train has the highest level of treatment, and provides for the widest range of potential customer requirements, it offers the best opportunity to maximise reuse and avoid disposal. The addition of advanced treatment reduces ammonia further which also assists in the reduction of the mixing zone and the initial dilution required to minimise the impact on the marine environment. Compared to the other scenarios with advanced treatment this scenario scored highest. Retaining the nearshore outfall reduces the risk of a ‘stranded asset’ if major recycling schemes are implemented and maintains flexibility to invest in recycling development. The scenario is hence scored moderately better than the base case. Scenario 6: (Ozone/BMF/UV/Chlorine & nearshore outfall). Very similar to Scenario 5 but scored slightly lower based on the lack of additional membrane filtration step and hence some potential customer preferences. Scenario 7: (Ozone/BMF/Chlorine & nearshore outfall). Scored lower than scenario 6 based on inability to meet the water quality required by the more sensitive uses and hence not as effective at avoiding disposal.


Scenario Treatment Upgrade Outfall Score 2 screens only current -3






SEPP Clause 29- Existing wastewater discharges (part 2)

Where a discharge cannot be avoided it must be below the low water mark and should be beyond the surf zone. Consider if the discharge is beyond the surf zone and how the receiving environment is impacted depending on whether the discharge is beyond the surf zone or in its current nearshore location. This criteria was scored primarily depending on whether or not there was an outfall extension included in the scenario. The SEPP requires application of the waste hierarchy and through the use of Environment Improvement Plans there is considerable flexibility in how best to meet the goals of wastewater management practices. The community and stakeholders have the opportunity to choose actions which are both affordable and help to protect the beneficial uses. The scenarios that include advanced treatment are designed to treat the wastewater in such a way that beneficial uses in the receiving environment are protected without the need to extend the outfall beyond the surf zone. The base case includes an extended outfall in combination with tertiary treatment to protect the beneficial uses. These two approaches are quite different however they can each be successful in protecting beneficial uses in the receiving environment. To avoid double counting with other criteria this criteria has been scored primarily based on whether or not the outfall is beyond the surf zone or not. Base Case: (tertiary filtration and extended outfall). Includes an outfall beyond the surf zone. The treatment provided does not reduce ammonia further from the current levels and still has 90th percentile ammonia levels around 10mg/L. Hence to address the residual issues in the receiving environment there is the need for an extended outfall.


Scenario 2: (no treatment upgrade & nearshore outfall). This is the current situation and was scored much worse than the base case. The outfall is not beyond the surf zone and there is no treatment upgrade (beyond the current ammonia reduction works in the secondary treatment area) to compensate and improve protection of beneficial uses. Scenario 3: (no treatment upgrade & extended outfall). The extended outfall will be beyond the surf zone. This was scored as being equivalent to the base case. Scenario 4: (Ozone/BMF/UV/Chlorine & extended outfall). The extended outfall will be beyond the surf zone. This was scored as being equivalent to the base case. Scenario 5, 6 & 7: (advanced tertiary treatment & nearshore outfall). These do not have an outfall beyond the surf zone and are hence scored as being moderately worse than the base case, although the beneficial uses are being protected through the additional benefits of advanced treatment. Scenario Treatment Upgrade Outfall Score







SEPP Clause 30 – Mixing zones

In issuing a licence EPA may approve a mixing zone where it is not practicable to avoid, reuse, recycle and effectively manage wastewater. Responsibility lies with the discharger to minimise the impact by keeping the mixing zone as small as possible and to show that they are continuously improving environmental management. Does the option show practicable measures to reduce the size or eliminate a mixing zone? Mixing zones are areas within a defined area where beneficial uses of the segment are not fully protected. A mixing zone can only be declared for substances which degrade within the mixing zone (e.g. freshwater) and chronic effects on the aquatic ecology outside of the mixing zone are to be avoided.


For the ETP discharge the volume of water being treated (from ~1.5 million people and 40% of Melbourne’s sewage) it is not currently practicable to avoid the treated effluent discharge completely. The outlook for Class A recycling applications indicates significant flow and load diversions opportunities over time to show continuous improvement. A major recycling scheme in the longer term could remove essentially all dry weather flow. Under wet weather conditions there will still be a need to discharge any excess flow. To maximise the opportunities for recycling and the effective management of wastewater (as discussed above in clause 29) it is essential that the treatment at ETP be upgraded. Upgrading the treatment fits with the continuous improvement requirement of the SEPP. All of the scenarios are expected to require some form of mixing zone, however the size and significance varies depending on the level of treatment and whether an outfall extension has been included or not. The outfall extension offers the advantage of relocating the residual freshwater and nutrients away from the immediate Boags Rocks area. The scenarios were scored as follows: Base Case: (tertiary filtration and outfall extension). The mixing zone changes are directly attributed to the outfall extension, in combination with the current ammonia reduction upgrade to the secondary treatment area at ETP. Scenario 2: (no treatment upgrade and nearshore outfall). This scored as being very much worse than the base case as there will be no change to mixing zones outcomes. There is no commitment to additional practicable measures to improve environmental management. Not upgrading the treatment limits opportunities to reduce the size of the mixing zone by reducing the volume of flow being discharged. Scenario 3: (no treatment upgrade & extended outfall). This scored a little worse than the base case, as not upgrading the treatment limits opportunities to improve environmental management by reducing the volume and loads being discharged. Scenario 4: (Ozone/BMF/UV/Chlorine & outfall extension). This scored slightly better than the base case. The level of treatment offered with the advanced is higher than the base case, is more likely to offer opportunities for ongoing flow and load reduction helping to facilitate avoidance of the discharge through recycling. The outfall assists in minimising the mixing zone through additional dilution.


Scenarios 5 & 6: (advanced tertiary treatment & nearshore outfall). This scored moderately worse than the base case as a small mixing zone remains at the current location. The mixing zone size is minimised through the treatment, and the very high quality of water which will assist in the facilitation of recycling and avoidance of the discharge into the receiving environment. Scenario 7: (Ozone/BMF/Chlorine & nearshore outfall). This scored slightly lower than scenarios 5 & 6 as although the initial mixing zone outcomes are similar it offers less opportunity to shrink this zone over time. Scenario Treatment Upgrade Outfall Score







Principle of Waste Hierarchy

Avoidance, Reuse, Recycling, Recovery of Energy, Treatment, Containment, Disposal. How does the option fit with the requirements of the waste hierarchy. Consider avoidance of discharge, facilitation of recycling, resource/energy recovery, treatment standard, wastes generated by the treatment etc.. The principles of the waste hierarchy include the following actions to be considered when looking to manage wastes. The first action to be undertaken is Avoidance- looking to avoid generation of waste or the waste discharge, if generation of the waste cannot be avoided then the following actions should be undertaken: • Reuse- use the waste • Recycling- change the waste into a form where it can be beneficially used rather

than becoming a waste • Recovery of Energy- obtain energy from the waste, in the case of tertiary or

advanced tertiary treatment this includes the recovery of energy from the treatment residuals

• Treatment- treat the waste to a standard suitable prior to disposal • Containment- prevent the waste from entering the environment • Disposal- least preferred method of managing waste


When scoring this criteria the scenarios associated with no upgrade to the treatment plant were less preferred as this is a continuation of the lowest ranking on the waste hierarchy which is disposal. The outfall extension is an investment in an asset that doesn’t promote higher uses on the waste hierarchy; rather it goes direct to the least preferred action of disposal. The options that included advanced treatment without an outfall extension were seen to be more favourable in that they promoted recycling which is significantly higher on the waste hierarchy. The three advanced process trains under consideration all ranked differently depending on the level of treatment applied, the energy used, the quality of water produced and how the level of treatment provided facilitates recycling. All of the treatment options use significant energy but also assist in the recovery of energy- additional solids are removed from the water and subsequently sent to the digesters from which energy is produced from the biogas. The energy inputs required for the treatment are scored separately in the energy/greenhouse criteria that follows. The scenarios were scored as follows: Base Case: (tertiary filtration & outfall extension). The treatment component assists with the facilitation of recycling which is an action high up the waste hierarchy. Scenario 2: (no treatment upgrade and nearshore outfall). This was scored as much worse than the base case as it does nothing to promote uses higher up the waste hierarchy other than disposal. Scenario 3: (no treatment upgrade and extended outfall). This scored as very much worse than the base case as it does nothing to assist with reuse/recycling or recovery of energy, as there is no treatment upgrade included- it goes direct to the least preferred outcome of disposal and potentially entrenches this approach. Scenario 4: (Ozone/BMF/UV/Chlorine & outfall extension). This scored as being a little better than the base case. The treatment being provided will produce an effluent with low colour and odour making it very suitable for recycled water applications. The outfall extension is the same as the base case hence this has no bearing on the scoring. This treatment option will produce less waste than that in the base case (e.g. used membranes, cleaning chemicals, UV lamps and ballasts)


Scenario 5: (Ozone/BMF/UF/Chlorine & nearshore outfall). This scored as slightly better than the base case. This level of treatment produces a very high quality of water that effectively promotes recycling. This treatment option will produce less waste than that in the base case (e.g. less used membranes and cleaning chemicals, no UV lamps and ballasts), but some wastes that are not a feature of scenarios 6 and 7 (some membranes and cleaning chemicals). The use of membrane materials and cleaning chemicals is more efficient than in the base case due to the effects of the upstream Ozone-BMF. By not extending the outfall it does not promote the disposal aspect of the waste hierarchy. Scenario 6: (Ozone/BMF/UV/Chlorine & nearshore outfall). This level of treatment produces a very high quality of water that effectively promotes recycling. This treatment option will produce less waste than that in the base case (e.g. no membranes and cleaning chemicals, much less UV lamps and ballasts). By not extending the outfall it does not promote the disposal aspect of the waste hierarchy. This scenario was scored as moderately better than the base case and slightly better than scenario 5 to differentiate between the additional membrane waste stream in scenario 5. Scenario 7: (Ozone/BMF/Chlorine & nearshore outfall). Less effective at reducing disposal than scenarios 5 and 6, but offers no waste stream from membranes or UV. Scenario Treatment Upgrade Outfall Score







Greenhouse/Energy

Consider the greenhouse implications of each scenario and the energy required and the ongoing sustainability of the scenario. The NPC includes the cost of the energy and offsets, however there is a broader issue of the inherent sustainability of each scenario and how it impacts on avoidance of additional demand.


Energy use in the operational phase of the project is significantly larger than embodied energy, and this dominates the total greenhouse impacts over the lifecycle considered (25 years). The scoring is calculated in direct proportion to the CO2e for each scenario if not offset. Scenario Treatment Upgrade Outfall Score







Impacts during construction

Includes dust, diesel, sediment runoff, flora & fauna, traffic, noise, marine impacts including geotech and full construction phase, etc. This criteria considers the full range of likely adverse impacts during construction activities of both the outfall extension and the tertiary treatment upgrade at ETP. Impacts that were considered include dust, noise, sediment, runoff, traffic and flora & fauna. All of these aspects would be considered in an environmental construction management plan, which would be prepared for any construction activities. The impact of geotechnical investigations required for successful design and construction was also considered in this criteria. Those options without the outfall scored higher than the base case and those with an outfall extension as there are less adverse impacts during construction when all of the activity is kept within the treatment plant. Although construction management plans would be in place, doing work in a sensitive area increases the inherent risks. The construction of the outfall will be through a national park and environmentally sensitive areas and likely to generate noise (from the Tunnel Boring Machine and other drilling activities), dust may be an issue, truck movements for removal of spoil and there is flora and fauna requiring protection in the area around.


The construction activities at ETP would be contained within the treatment plant site, with the exception of truck movements, however these are likely to be on major roads and freeways and not impact on local residences. Base Case: (tertiary filtration and extended outfall). This requires work at both ETP and Boags Rocks. Scenario 2: (no treatment upgrade and nearshore outfall). This has very limited works at ETP and was scored as moderately better than the base case. Scenario 3: (no treatment upgrade and extended outfall). All of the works are at Boags Rocks which is a sensitive and complex work area. As there is no work at ETP it was scored as being slightly better than the base case. Scenario 4: (Ozone/BMF/UV/Chlorine & extended outfall). Works are very similar to those required in the base case and was scored as being equivalent. Scenario 5, 6 & 7: (advanced tertiary treatment & nearshore outfall). There is no works required at Boags Rocks, hence the likely impacts during construction are confined to ETP. This was seen as having a lower impact than the base case and was scored as being a little better. Scenario Treatment Upgrade Outfall Score


3 screens only extended 0.5





6.5 Assessment Outcomes

The Environment Protection Act includes the Principle of Integration of Economic, Social and Environmental Considerations. It indicates the improvement measures adopted should be proportional to the significance of the environmental issues being addressed, and this serves as a useful summary of the TBL process and outcomes.


Eastern Treatment Plant is an asset of state significance, in that it treats the sewage from ~1.5 million people or around 40% of Melbourne’s sewage. The treated effluent is discharged to an area where it has influenced the marine environment over the past 35 years, however that ecosystem is not unique on the Victorian coastline. The ammonia reduction project has reduced this impact, and advanced tertiary treatment offers the potential to reduce the ecological, aesthetic/amenity and recreational health risk impacts even further, to the point where the issues of concern are addressed, and only a small residual mixing zone is required. Recent results from climate change projections have shown that sea level rise may impact the rocky platforms at Boags Rocks such that they will no longer offer intertidal habitat zones. The cost to go beyond the advanced tertiary treatment and also construct an outfall extension to facilitate the final small of area intertidal platform recovery immediately at Boags Rocks is substantial in terms of cost, potential construction impacts and community concerns. This brings in to question it’s practicability for this situation. Base Case: (tertiary filtration and outfall extension). The base case will address the impacts in the marine environment, however it will be at a very substantial cost to the community of around $800 million. The treatment will improve the effluent quality making it suitable for a wide range of recycled water applications, however it will not address the colour or odour associated with the recycled water. Scenario 2: (no treatment upgrade and nearshore outfall). While clearly the lowest cost, this scenario offers no change to the current environmental impacts and does not meet community or regulatory expectations for improving wastewater management. Scenario 3: (no treatment upgrade and outfall extension). This scenario provides impact reduction in the receiving environment through the use of dilution and is of lower cost than the base case, but does not fully address the recreational health risk aspects and some residual aesthetic risks remain. It does nothing to facilitate the move from waste disposal to resource recovery and hence apply the waste hierarchy principles. Social concerns with this approach have been previously expressed. Scenario 4: (Ozone/BMF/UV/Chlorine & extended outfall). This offers additional benefits over the base case, and the cost benefit of the treatment process is slightly more advantageous than the base case. It offers the highest level of improvement of the scenarios but at still very significant overall cost to the community.


Scenarios 5 & 6: (advanced tertiary treatment & nearshore outfall). These scenarios offer sufficient treatment measures to ameliorate the environmental issues without incurring the substantial cost, potential construction impacts and community concerns associated with an outfall extension. Scenario 6 is more advantageous than 5 as it offers the necessary degree of marine benefits, and provides for Class A recycling applications, without the added lifecycle costs and energy use of the membranes in scenario 5. Scenario 7: (Ozone/BMF/Chlorine & nearshore outfall) is similar to, but not as effective as scenarios 5 & 6 at addressing recycled water requirements (resulting in less potential environmental benefit through flow diversions) and further reducing recreational health risk. Given its minimal cost savings over scenario 6, it hence scores lower from a TBL perspective. The outcomes from the TBL assessment are presented graphically below for each weighting sensitivity case.


Total TBL Scores (Higher = better outcome)

0.024 0.023

0.141

0.228

0.254

0.187

0.00

0.05

0.10

0.15

0.20

0.25

0.30

No treatment upgrade+ fine screens +nearshore outfall

No treatment upgrade+ fine screens &extended outfall

Advanced tertiary(O3+BMF+UV+Cl) &

extended outfall

Advanced tertiary(O3+BMF+UF+Cl) &

nearshore outfall


nearshore outfall

Advanced tertiary(O3+BMF+Cl) &nearshore outfall

Scenarios 2-7 left to right (scored relative to base case of Scenario 1)

Relat

ive S

core

for R

ankin

g Pu

rpos

es

Environment 40%Social 20%Economic 40%


0.051 0.055

0.142

0.216

0.246

0.187

0.00

0.05

0.10

0.15

0.20

0.25

0.30




extended outfall


nearshore outfall


nearshore outfall



Relat

ive S

core

for R

ankin

g Pu

rpos

es




-0.004

0.025

0.142

0.203

0.229

0.166

-0.05

0.00

0.05

0.10

0.15

0.20

0.25




extended outfall


nearshore outfall


nearshore outfall



Relat

ive S

core

for R

ankin

g Pu

rpos

es



-0.058

-0.002

0.137

0.180

0.200

0.131

-0.10

-0.05

0.00

0.05

0.10

0.15

0.20

0.25




extended outfall


nearshore outfall


nearshore outfall



Relat

ive S

core

for R

ankin

g Pu

rpos

es




-0.116

-0.057

0.135

0.1870.200

0.119

-0.15

-0.10

-0.05

0.00

0.05

0.10

0.15

0.20

0.25




extended outfall


nearshore outfall


nearshore outfall



Relat

ive S

core

for R

ankin

g Pu

rpos

es



-0.123

-0.024

0.138

0.1540.169

0.097

-0.15

-0.10

-0.05

0.00

0.05

0.10

0.15

0.20




extended outfall


nearshore outfall


nearshore outfall



Relat

ive S

core

for R

ankin

g Pu

rpos

es




-0.183

-0.076

0.136

0.159 0.165

0.082

-0.20

-0.15

-0.10

-0.05

0.00

0.05

0.10

0.15

0.20




extended outfall


nearshore outfall


nearshore outfall



Relat

ive S

core

for R

ankin

g Pu

rpos

es


Scenarios 5 and 6, involving variants of advanced tertiary treatment and no outfall extension, are strongly preferred - they are superior financially to Scenarios 1 & 4, and offer greater overall social, environmental/policy benefits than Scenarios 2 & 3 Of these two, Scenario 6 - Advanced tertiary (Ozone/BMF/UV/Chlorine) & current nearshore outfall is ranked highest, offering sufficient treatment to ameliorate the most significant environmental effects and support a broader range of recycled water applications. Sensitivity analysis varying the criteria weighting indicates Scenario 6 is consistently preferred.

6.6 Conclusions

Significant environmental improvements will be achieved at the discharge point from implementation of advanced tertiary treatment, plus the current ammonia reduction works, plus the progressive development of recycling diversions over time. Based on the full range of Triple Bottom Line factors, the improvements resulting from the proposed treatment upgrade are expected to improve the overall marine environment to the extent that the dis-benefits of any residual shorter term


freshwater or nutrient impacts within a defined small mixing zone are outweighed by the impacts and significant costs associated with construction of an extended outfall. Even within the residual mixing zone, significant environmental benefits accrue from the proposed changes associated with advanced tertiary treatment, including reduction of the suspended solids food source for Boccardia, major improvements to water clarity, and addressing the toxicity impacts on the key macroalga indicator H. Banksii.. The $400M cost of extending the outfall, and the impacts associated with construction, would be incurred to facilitate more extensive recovery of a small area of potential habitat for H. Banksii.(Neptunes Necklace) and Durvilleae (Bull Kelp). This area is located immediately adjacent to the discharge point. This habitat is not unique at Boags Rocks. These species and other such intertidal rocky platforms are widely found along the South East Australian coastline. It is hence proposed that an outfall extension not be included in the overall works package. The outcomes delivered by this proposal would be consistent with achieving overall value for money for the community, community views around improved treatment versus outfall extension, and underpinning the development of further recycled water initiatives as outlined in Section 3.6. The outcomes of the TBL assessment support this, taking into account: • Results of trials to verify process performance and achievable effluent quality • Updated costing for all options • Viability of treatment to address shoreline discharge issues • Assessment of options against policy and regulation • Strategic fit with long term integrated water resource utilisation The very high level of treatment proposed would clearly represent best practice for large scale treatment for marine discharges, and in many respects would be regarded as world leading. The benefits of this treatment are reflected in the very small size of residual mixing zones proposed for the purposes of managing 40% of Melbourne’s wastewater. In 2002 the Panel appointed by EPA Victoria to carry out an assessment of the then Works Approval proposal (under section 20B of the Environment Protection Act), indicated that an outfall extension should be incorporated in the overall works package. As discussed throughout this submission, there have been major changes to


the factors influencing this decision including the level of treatment offered, climate change and water resource issues, the outlook for flows and loads to the receiving environment, and our understanding of the marine impacts. The Panel’s issues (in italics) are discussed in turn below. The risk of foams/solids causing impacts at the point of discharge - The Ozone-BMF process will reduce any residual foam forming potential to a level comparable to tap water. Biological foam formers are removed by the proposed treatment. Oil and grease levels are further reduced. Solids and surfactant effects are comprehensively removed by the treatment. This will build upon the improvements that have been observed from treatment improvements in recent years. Allow for the ecosystem recovery and compliance with SEPP mixing zones requirements - The Ozone-BMF process will reduce the toxicity of the discharge at Boags Rocks through a combination of further reduced ammonia levels and a broad spectrum barrier to other potential minor toxicants. The most sensitive species for ammonia toxicity is consistently protected by the advanced tertiary process, leaving only residual freshwater effects which are addressed by a safe dilution of 20:1 for the most salinity sensitive test (scallop larval development). Hydrodynamic modelling indicates the 20:1 safe dilution is achieved within a radius of 250m from the discharge point. The small residual mixing zone is provided for in the SEPP (WoV), and even within the residual mixing zone, significant environmental benefits accrue from the proposed changes including reduction of the suspended solids food source for Boccardia, major improvements to water clarity, and addressing the toxicity impacts on the key macroalga indicator H. Banksii.. Effects within a defined mixing zone can be expected to further decline over time as the trend towards diversions of freshwater and nutrient loads to recycling continues. Necessary to ensure the recreational amenity of swimmers and surfers - The advanced tertiary treatment process ensures the recreational amenity of swimmers and surfers by comprehensively addressing the microbiological concerns and the aesthetic issues associated with the current discharge. In the medium term it is unlikely that complete reuse of the effluent stream can be achieved, therefore, an outfall will be required to manage freshwater toxicity - The science on freshwater impacts has been clarified by the extensive ecotox testing program. The residual freshwater effects are addressed by a safe dilution of 20:1 for


the most salinity sensitive test (scallop larval development), and this is achieved within a radius of 250m from the discharge point. The treated effluent flows outlook has changed significantly in the intervening years. The overall picture is now one of declining flows and loads to the environment. Successful adaptation to the uncertainties of climate change, and the drivers for increased utilisation of fit for purpose water resources where practicable, will continue this trend. Current plant inflows are around 20% lower than the outlook considered by the Panel in 2002 and this translates to lower flows to the outfall. The local recycling developments have the potential to significantly enhance this, taking up to one third of the total flow, until such time as the overall community benefit of larger scale recycling schemes becomes favourable and the diversion of the balance of dry weather flows becomes feasible. High end reuse schemes in the long term will generate a brine stream requiring disposal - If a brine outfall were to be required in the long term it would only be required to take flows in the order of one hundredth to a maximum of one tenth that under consideration for current peak flows. This massive reduction in scale means a very different form and impact of outfall construction, and of course cost. A nearshore outfall compared with international best practice - In consideration of international best practice, it is necessary to consider the combination of treatment and disposal methods together. Long outfalls were generally built prior to implementation of treatment to either primary or secondary treatment. The advanced tertiary treatment process proposed for ETP is at the forefront of international best practice for a wastewater plant, and clearly represents best practice for discharges to the open marine environment. The treatment outcomes achieved allow for retention of a near shore discharge. The panel based it’s considerations of an outfall extension at the time on indicative cost estimates developed in the 1990’s, which suggested costs an order of magnitude lower than the more rigorously developed designs and cost plans now available. This may have made it more attractive to include an outfall extension in the overall works package. The early cost estimate was a very early concept based on a bottom-tow construction method comprising two pipelines which would be buried across the shoreline and to at least the 5m depth contour. Beyond this a trench would be excavated in the seabed. Extensive work has been undertaken by outfall construction experts in the years since, and a thorough understanding of the required scope and costs is now in place.


This work has indicated the original construction method presents significant difficulties and risks associated with constructing large pipelines through the surf zone in this high energy coastline. It is not considered feasible. This method would also involve substantial disruption to the highly sensitive environmental foreshore and dunes area. Consequently, the construction method was changed to tunnelling. Following a detailed investigation into design, construction methodology and an updated costing taking into account a thorough assessment of current construction costs and risk, items a RANE P50 estimate of $399M was established by independent experts. As discussed in section 3.7.3 of this report, the SEPP requires the practicability of the proposed action to be taken into account to ensure that the environmental benefits justify the social and financial costs. This requires consideration of the following issues: • the severity of the environmental risk in question and the environmental benefits of

removing or mitigating that risk; • the state of knowledge of the environmental risk and options for removing or

mitigating that risk; • the availability, efficiency and suitability of options to remove or mitigate that risk;

and • the financial and social costs and benefits of removing or mitigating that risk. The Advanced Tertiary and ammonia reduction upgrades, in conjunction with ongoing recycling development, will have a significant environmental benefit. An outfall extension, in addition to the Advanced Tertiary upgrade, would also address the residual localised impacts caused by freshwater and nutrients by relocating the discharge and increasing the initial dilutions in the marine environment. However, Melbourne Water is of the view that this environmental benefit does not outweigh the financial and social costs of an outfall extension. The TBL assessment has considered the options available. The TBL assessment outcomes show that scenarios which include Advanced Tertiary but no outfall extension, have a significantly better outcome than scenario 3, which includes both Advanced Tertiary and an outfall extension. This supports Melbourne Water's conclusion that an outfall extension is not practicable in the circumstances.


7.1 Proposed Works

The proposed works to implement the Advanced Tertiary Treatment upgrade at ETP are described in the Concept Design Report, attached as Appendix 5. This upgrade will build on the environmental benefits of the current Ammonia Reduction project, and support the development of increased recycling.

7.2 Residual mixing zone requirements

The current ETP Licence mixing zones are illustrated in Appendix 1, and their origin goes back to very early versions of the licence. They predate all of the scientific understanding generated since the mid 1990s, and hence predate the new approach of looking at receiving environment ecology and biota and impacts on specific species through toxicity testing. Safe dilution is a concept now widely used in environmental toxicology and enshrined in the ANZECC 2000 Fresh and Marine Water guidelines. Ecotox tests are carried out on a range of species, and from the results it is possible to calculate a safe dilution to protect marine species. The species selected for the ETP testing are considered the most relevant to the Boags Rocks receiving environment. This approach is widely used and approved worldwide. The whole effluent toxicity testing yields the overall impact of the effluent and it’s properties and constituents. A safe dilution of 1:20 for the advanced tertiary effluent can be combined with the dilutions from the high resolution hydrodynamic modelling work carried out in recent years to yield mixing zone sizes as illustrated in Appendix 1. MW has proposed a toxicant mixing zone based on “safe dilution” which has a 50% confidence level. To estimate the mixing zone dimensions the average dilution contour determined by hydrodynamic modelling (as discussed in Section 2.6.1) has been used. An alternative more conservative approach to describing this zone would be to use a 5th percentile dilution contour line. This would not change the actual environmental effects or outcomes, rather it simply describes a larger area to be more conservative. The effect of this on the mixing zone dimensions can be seen in the table below (derived from Table 2-3, interpolated between specific modelled locations where required).

7. Proposed path forward


Table 7-1: Dimensions of 20:1 Dilution Contours

East West Offshore

Average 20:1 dilution contour 260 180 200

5th percentile 20:1 dilution contour 500 270 250

There is an approximate factor of 2 in mixing zone area, depending on use of average or 5th percentile dilution. This precision is consistent with the 50% confidence level on the safe dilution. The more subtle potential effects of nutrients such as particulate organic carbon (the suspended solids in the current secondary effluent) and nitrogen are more difficult to define in terms of their zone of influence. The proposed treatment upgrade will substantially reduce the suspended solids currently favouring the growth of Boccardia within 150m of the discharge point, and thus further shrink the area so affected. It is proposed to base an initial nutrient mixing zone around beneficial use protection, and in particular on the observable limitations to H. Banksii. recovery on otherwise viable habitat. Based on the recent recovery observed at Fingals Beach, such a definition would yield a nutrient mixing zone covering just the intertidal platform area in the immediate vicinity of the discharge (Boags and Boags East). The outlook for nitrogen loads indicates around 60-70% reduction from the mid 1990s, and development of recycling diversions would reinforce these gains. The very high level of treatment proposed would clearly represent best practice for large scale treatment for marine discharges, and in many respects would be regarded as world leading. The benefits of this treatment are reflected in the very small size of residual mixing zones proposed for the purposes of managing 40% of Melbourne’s wastewater. Even within the residual mixing zone, significant environmental benefits accrue from the proposed changes including reduction of suspended solids food source for Boccardia, major improvements to water clarity, and the toxicity impacts on the key macroalga indicator H. Banksii. are addressed. The broader policy and strategic direction to make greater use of this potential resource through recycling will build on these gains for the marine environment as freshwater volumes and nutrient loads decline further through diversion to recycling applications. This will facilitate continuous improvement and the opportunity to shrink the mixing zones even further.


The proposed arrangements are consistent with provisions of the State Environment Protection Policy (SEPP) Waters of Victoria. Appendix 1 also includes an illustration of the current aesthetic observations data area, and the expected major change post the implementation of advanced tertiary to address the current impacts.

7.3 Timelines

A high level outline of key activities is included below.

Activity Jul-0

9

Aug

-09

Oct

-09

Nov

-09

Dec

-09

Feb-

10

Mar

-10

May

-10

Jun-

10

Jul-1

0

Feb-

11

Mar

-11

Sep-

11

Oct

-11

Jun-

12

Jul-1

2

Sep-

12

Oct

-12

Dec

-12

Jan-

13

Approvals Process

Works Approval

Business Case

Ammonia Reduction Works

Stage 2 Construction Completion

Commissioning

Advanced Tertiary Implementation

Pilot Plant Work for Design & Commisioning Support

Concept/Functional Design

Detailed design

Procurement

Site Preparation

Construction

Commissioning

DHS Accreditation

Ongoing Monitoring Program Figure 7-1: Indicative Timeline

7.4 Environmental Monitoring Program

The proposed monitoring program is based on the rigorous approach developed in consultation with EPAV as the detailed scientific understanding has been accumulated. The key elements of the program are outlined in Section 2.5.10 and additional detail is provided in Sections 4 and 5 of Appendix 3. This program forms an important part of the adaptive management approach (described in Section 1.5) which has underpinned the work to date and will continue to ensure robust decision making in improving environmental performance for ETP.


The program includes the sampling and monitoring methods to detect change and assess the benefits of the proposed works.


1. Mixing Zones

2. Discharge Aesthetics & Amenity Summary 2009

3. 2004-2007 Monitoring Report (CSIRO et.al.)

4. Hydrodynamic Modelling Report 2009 (GHD)

5. Concept design of Advanced Tertiary Treatment Plant (Black & Veatch/KBR)

6. Outfall Concepts & Updated Costing 2009 (GHD)

Appendices

eastern treatment plant upgrade: information in · pdf fileeastern treatment plant upgrade:...

Documents