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Eastern Treatment Plant Tertiary Upgrade Project

CONCEPT DESIGN REPORT FOR WORKS APPROVAL SUBMISSION 2009

Prepared by: Black & Veatch Australia Pty Ltd Level 6, 492 St Kilda Road, Melbourne 3004 Telephone (03) 8673 4200.

and Kellogg Brown & Root Pty Ltd Level 3 441 St Kilda Road Melbourne Victoria 3004 Telephone (03) 9828 5333, Facsimile (03) 9820 0136 July 2009

TABLE OF CONTENTS Executive Summary ............................................................................................................ 1

1 Introduction............................................................................................................. 4 2 Eastern Treatment Plant overview.......................................................................... 5

2.1 General ............................................................................................................ 5 2.2 Plant flows ...................................................................................................... 6 2.3 Feed water quality........................................................................................... 9

2.3.1 Introduction............................................................................................. 9 2.3.2 Indicative feed water quality................................................................. 10 2.3.3 Forms of nitrogen, pH and alkalinity.................................................... 11

3 Advanced Tertiary Treatment Plant...................................................................... 12 3.1 Process overview .......................................................................................... 12 3.2 Treated water quality .................................................................................... 14 3.3 Design flows ................................................................................................. 16

3.3.1 Existing flows ....................................................................................... 16 3.3.2 Design capacity..................................................................................... 17

4 Site layout and constraints .................................................................................... 18 4.1 Plant location ................................................................................................ 18 4.2 Plant layout considerations ........................................................................... 18 4.3 Materials of construction .............................................................................. 20 4.4 Hydraulic considerations .............................................................................. 21 4.5 Geotechnical considerations ......................................................................... 22

5 Process units.......................................................................................................... 23 5.1 ATTP feed water management ..................................................................... 23 5.2 Tertiary Supply Pump Station....................................................................... 23 5.3 Ozone treatment ............................................................................................ 25

5.3.1 Description............................................................................................ 25 5.3.2 Ozone system design basis.................................................................... 25

5.4 Biological media filtration ............................................................................ 33 5.4.1 Description............................................................................................ 33 5.4.2 Biological media filtration design basis................................................ 34

5.5 UV disinfection system................................................................................. 38 5.5.1 Description............................................................................................ 38 5.5.2 UV system design basis ........................................................................ 39

5.6 Chlorine disinfection..................................................................................... 41 5.6.1 Description............................................................................................ 41 5.6.2 Chlorine disinfection system design basis ............................................ 41

5.7 Treated water storage.................................................................................... 43 5.8 Residuals management.................................................................................. 44

5.8.1 Description............................................................................................ 44 5.8.2 Backwash balancing tank...................................................................... 45 5.8.3 Residual solids separation and thickening – tertiary DAFT system ..... 45 5.8.4 Residuals stabilisation........................................................................... 47

ETP Tertiary Upgrade Project Page i Concept Design Report 2009

5.9 Alkalinity correction system......................................................................... 48 5.10 Electrical system ........................................................................................... 49 5.11 Instrumentation, control and automation ...................................................... 50

5.11.1 General .................................................................................................. 50 5.11.2 Integration considerations..................................................................... 51 5.11.3 ATTP control system architecture ........................................................ 51 5.11.4 Control philosophy................................................................................ 52 5.11.5 Interfaces with existing systems ........................................................... 52

5.12 Flexibility for future process enhancements – Membrane filtration............. 52 6 Operational reliability and redundancy................................................................. 54

6.1 Introduction................................................................................................... 54 6.2 General ATTP design considerations ........................................................... 55 6.3 Tertiary supply pump station ........................................................................ 56 6.4 Ozone system................................................................................................ 56 6.5 Biological media filtration system................................................................ 57 6.6 Residuals handling system............................................................................ 57 6.7 UV disinfection system................................................................................. 58 6.8 Chlorine disinfection system......................................................................... 59 6.9 Treated water storage.................................................................................... 59

7 Environmental and social considerations.............................................................. 60 7.1 Introduction................................................................................................... 60 7.2 Air ................................................................................................................. 60 7.3 Noise ............................................................................................................. 61 7.4 Surface water and ground water ................................................................... 61 7.5 Land .............................................................................................................. 62 7.6 Flora and Fauna............................................................................................. 63

7.6.1 Flora ...................................................................................................... 63 7.6.2 Birds...................................................................................................... 63 7.6.3 Bats ....................................................................................................... 65 7.6.4 Other ..................................................................................................... 66

7.7 Cultural heritage............................................................................................ 66 7.8 Community engagement ............................................................................... 66 7.9 Waste and materials use................................................................................ 67

7.9.1 Materials use ......................................................................................... 67 7.9.2 Residual solids ...................................................................................... 68 7.9.3 UV lamp cleaning ................................................................................. 68 7.9.4 Other consumables................................................................................ 69 7.9.5 Ozonation off-gas.................................................................................. 69

7.10 Power consumption and carbon footprint ..................................................... 70 7.10.1 Power consumption............................................................................... 70 7.10.2 Carbon footprint.................................................................................... 70

8 Cost estimates ....................................................................................................... 73 Appendix A: Historical effluent quality data at Eastern Treatment Plant ............. 75 Appendix B: Project Drawings.............................................................................. 78

ETP Tertiary Upgrade Project Page ii Concept Design Report 2009

Executive Summary In October 2006, the Victorian Government announced that the Eastern Treatment Plant (ETP) treated effluent discharge will be upgraded with the project due for completion in 2012. The upgrade is a key initiative in the Government's plan to secure our water future. The objectives of the ETP Tertiary Upgrade Project are to:

• Significantly improve treated water quality which will address the impact of the current discharge to the receiving marine environment at Boags Rocks on the southern Mornington Peninsula, and

• Create a high quality fit-for-purpose recycled water resource for use in a wide range of non-potable recycling applications.

Melbourne Water has undertaken the Tertiary Technology Trials, comprising extensive pilot-scale testing of the candidate treatment technologies, which has provided invaluable data to inform options development, engineering design, assessment and cost estimation activities and thereby result in selection of the most advantageous treatment option. The proposed scope of the upgrade includes implementation of a new treatment plant at ETP comprising both tertiary treatment and advanced treatment concepts to deliver a broad range of treated water quality benefits to meet the project objectives. This report provides concept design information for the proposed Advanced Tertiary Treatment Plant and is intended as a supporting attachment to the Works Approval Application which Melbourne Water will be submitting to EPA Victoria for the ETP Tertiary Upgrade Project.

The proposed Advanced Tertiary Treatment Plant will be incorporated into the ETP treatment process between the existing Holding Basins, which store secondary treated effluent, and the Outfall Pump Station, and consists of the following major elements:

The Tertiary Supply Pump Station will lift secondary effluent from the Holding Basin Return Channel into the Advanced Tertiary Treatment Plant. The pump station will have variable output across the full plant design flow range. Flow through the remainder of the Advanced Tertiary Treatment Plant will be by gravity. Ozone will be dosed to treat the aesthetic parameters of colour and odour, increase the UV transmittance, provide disinfection, and oxygenate the feed flow to the downstream biological media filters. Ozone will be generated on-site from oxygen feed gas supplied by a combination of onsite oxygen generation and liquid oxygen storage. Ozone will be dosed into twin pipeline contactors via side-stream injection.

ETP Tertiary Upgrade Project Page 1 of 87 Concept Design Report 2009

Biological media filters will remove particulate matter, biodegrade organic compounds and reduce ammonia by nitrification. The filters will be based on a gravity down-flow granular media configuration with automatic backwashing (cleaning) systems. Ultraviolet disinfection will provide further pathogen reduction and specifically target protozoa and bacteria. The ultraviolet disinfection system is expected to be based on low pressure high output lamp technology to maximise energy efficiency in either an open channel or closed reactor configuration. Chlorine disinfection will provide further pathogen reduction and a disinfection residual to specifically target viruses and bacteria. The chlorine system will utilise the existing ETP chlorine plant and be capable of operating in both free chlorine and combined chlorine (chloramine) disinfection modes. Treated water storage will be provided by twin 32 ML basins constructed with earthen embankments and both lined and covered to maintain treated water quality. The treated water storage will provide both contacting volume for disinfection with either free or combined chlorine and hydraulic buffering storage between the Advanced Tertiary Treatment Plant and the downstream Outfall Pump Station to facilitate the balancing of flows and minimise stop/start operation. Residuals handling systems will be provided to handle the backwash solids stream from the biological media filters. The solids from this stream will be removed and thickened by a dissolved air flotation process using polymer and coagulant to improve process performance. The thickened solids stream will be fed to the existing ETP sludge digesters for stabilisation and gas production, and the clarified effluent stream will be returned to the Effluent Holding Basins. The Advanced Tertiary Treatment Plant will provide the following treated water quality benefits:

• The risk of plume visibility at Boags Rocks will be significantly reduced even if the current nearshore discharge is retained. This will be achieved through a combination of significant solids, foam and colour reduction as described below.

• Suspended solids will be reduced by around 80% at median conditions and 90% at 95th percentile conditions, thereby reducing the risk of plume visibility and improving the visual clarity of the water in the marine environment, and reducing the food source for opportunistic species at Boags Rocks.

• Activated sludge plant foam will be completely removed, and the residual foam forming potential of the discharge will be reduced to a level comparable to drinking water.


• True Colour will be significantly reduced by around 80 to 85% at both median and 95th percentile conditions, and typically down to levels comparable to drinking water thereby improving recycled water aesthetic quality.

• Litter will be completely removed. • The precursors to fat balls, being oil and grease, will be eliminated. • The odour level of the discharge will be reduced and the odour character

improved which both will be of benefit both at Boags Rocks and in terms of improving recycled water aesthetic quality.

• Pathogens will be extensively reduced by the order of 4-6 log (99.99 to 99.9999% reduction) for each of bacteria, protozoa and viruses to further reduce the health risks associated with the recreational use of the marine environment and address the requirements for high quality fit-for-purpose recycling applications.

• Discharge toxicity in the marine environment will be further reduced in terms of both residual ammonia toxicity and other minor toxic components of the ETP effluent.


1 Introduction

In July 2008, Black & Veatch in association with KBR was appointed by Melbourne Water to undertake engineering services for Eastern Treatment Plant (ETP) Tertiary Upgrade Project, Phase 1 – Option Design, Costing and Assessment. This work included developing and assessing candidate process trains for the ETP Tertiary Upgrade Project to meet the following project objectives:

• To significantly improve treated water quality which will address the impact of the current discharge to the receiving marine environment at Boags Rocks on the southern Mornington Peninsula.

• To create a high quality fit-for-purpose recycled water resource for use in a wide range of non-potable recycling applications.

In addition to typical tertiary treatment processes comprising some combination of filtration and disinfection processes, the introduction of advanced treatment presents the opportunity to more fully address residual issues for the receiving marine environment and provide a more robust platform for possible future recycling applications. The Tertiary Trials Plant, which has been in operation since February 2008, has provided invaluable data to inform the development of preliminary process designs, for which engineering designs and cost estimates have been prepared, as described in this report. This report provides concept design information for the proposed Advanced Tertiary Treatment Plant (ATTP) and is intended as a supporting attachment to the Works Approval Application to EPA Victoria for the ETP Tertiary Upgrade Project.


2 Eastern Treatment Plant overview

2.1 General

The ETP, at Bangholme in Melbourne’s south east, provides an essential public health service, processing about 40% 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. Treated effluent is pumped by the Outfall Pump Station along a 56 km pipeline to the South East Outfall at Boags Rocks on the southern Mornington Peninsula, where it is discharged into Bass Strait under the licence conditions set by EPA Victoria (EM35642). 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). A technical summary of the existing ETP systems and processes is provided below:

1. Sewage gravitates into the influent pumping station and is pumped to either 19 mm bar screens or 5 mm fine screens, followed by pre-aeration and grit removal. The screenings and grit removed are dewatered prior to landfill disposal.

2. The de-gritted flow passes to the primary sedimentation tanks, where settled sludge is collected and pumped to anaerobic digesters. Floating scum is currently directed to the head of the tank by water jets and pumped to the digesters.

3. Settled sewage flows to the step-feed activated sludge aeration tanks. Oxygen is supplied by fine-bubble diffused aeration supplied by centrifugal blowers.

4. Mixed liquor from the aeration tanks is discharged to secondary sedimentation tanks where activated sludge is settled out and clarified effluent overflows to the secondary effluent channel and then on to effluent holding basins.

5. Most of the settled sludge from the secondary sedimentation tanks is returned to the aeration tank. Excess biomass is pumped to dissolved air flotation tanks and centrifuges for thickening, then stabilised by anaerobic digestion in conjunction with the primary sludge. Digested sludge is dried in sludge drying pans. The dried sludge is harvested during warm weather and stored for 3 years prior to reuse.

6. Clarified effluent flows by gravity to the Effluent Holding Basins (EHBs). These basins provide balancing storage for diurnal flow variations and wet weather events, and a degree of effluent polishing.


7. Immediately prior to the Outfall Pumping Station (OPS), effluent is filtered through 3 mm opening screens to remove any residual foreign matter that has survived the treatment process, and disinfected by dosing gaseous chlorine. The effluent is then pumped to the South East Outfall (SEO) via the OPS at a rate of 3.0 to 7.6 kL/s depending on plant service water diversions and the number of OPS pumps in operation.

8. Part of the effluent is recycled back to the plant for process water known as 2W and 3W water.

9. The SEO includes a ten kilometer rising main section and a gravity section. Discharge is to Bass Strait at Boags Rocks, 56 km from ETP.

10. Gas produced by the anaerobic digestion process is used primarily to generate electricity which is used within the plant. Heat recovery equipment fitted to each gas engine provides sludge and space heating.

11. Plant process control is by distributed redundant PLCs, and a central control room. The control room contains the operator interface.

12. Power is supplied to the site at 22 kV. This is stepped down to 6.6 kV and distributed at this voltage to switchboards at the Influent Pumping Station and Aeration Blower Building to supply the large motors.

2.2 Plant flows

Historical average annual inflows to ETP are presented in Figure 2.1 below. The trends in flows to ETP have been influenced by the following factors:

• The success of waste minimisation, infiltration/inflow reduction, and water demand management measures from the late 1980’s onwards, including a slowing in Melbourne’s population growth and until more recent years.

• 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 ETP. This approach optimises system operation, wet weather flow management, and augmentation over the next 20 years.

• Recent decline in flows into ETP as a result of drought and water saving being implemented across the catchment.

The average annual inflow to ETP over the three years of 2006/07/08 ending 30 June was 330 ML/d, and that over the last three years 2007/08/09 was 307 ML/d.


Previous projections of flow growth at ETP have now been downgraded and current flow projections indicate an essentially flat growth outlook with average flows likely to remain below 360 ML/d due the continued benefits of demand management initiatives offsetting any growth in connected population.

100

150

200

250

300

350

400

450

500

1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010

YEAR ENDING 30 JUNE...

AVE

RA

GE

AN

NU

AL

FLO

W

Note average annual inflow to ETP is at its lowest since 1988

Figure 2.1 ETP influent trend

The existing ETP primary and secondary treatment systems and EHBs have a nominal peak wet weather capacity of 1,700 ML/d. The peak capacity of the OPS, the only means for discharging treated effluent from the site, is around 700 ML/d. Wet weather flows in excess of the OPS capacity are temporarily stored in the EHBs. To empty these storages the OPS is required to operate at maximum output for durations dependent on the severity and duration of the wet weather event, the impact of successive events on accumulated effluent storage, and the weather outlook. Analysis of historical records of OPS outputs in association with wet weather flows indicates a similar declining trend to that presented in Figure 2.1 above. Based on the previous 20 years, the 90th percentile was 24 days’ operation at peak output per year, and the average was 12. The average over the 10 years from 1997 to 2008 was 9 days per year, and based on the current outlook the OPS could be expected to operate at peak output for 5 to 10 days a year on average.


While the average daily net production of the ATTP will match the normal dry weather flow of ETP, including internal recycle flows, the treatment and hydraulic capacity of the ATTP is directly related to the existing OPS capacity plus any additional flows required within ATTP such as process backwash flows. The relationship between peak wet weather flows, the EHB system and the OPS capacity lead to the proposed ATTP having to be capable of addressing the following flow scenarios:

Wet weather: Up to 700 ML/d (three duty OPS pumps in operation) treated water production for 5 to 10 days per year on average and up to 4+ weeks in a wet year, and meeting process water requirements.

Dry weather: From minimum flow, up to 570 ML/d (two duty OPS pumps in

operation) treated water production on a year round basis, and meeting process water requirements.

The ATTP will be capable of operation at variable output from minimum flow up to peak flow. The specific capacity requirements for the ATTP are discussed further in Section 3.3. A basic schematic of the hydraulic integration of the ATTP with existing ETP assets is provided in Figure 2.2 below.

ETP1o & 2o TREATED WATER

STORAGE

ADVANCED TERTIARY

TREATMENT PLANT (ATTP)

1700 ML/D PEAK CAPACITY UP TO 700 ML/D PEAK CAPACITY TO OPS

STATIONPUMP

OUTFALLEFFLUENTHOLDINGBASINS

Figure 2.2 Hydraulic integration of ATTP with existing ETP assets


2.3 Feed water quality

2.3.1 Introduction

This section discusses the quality of secondary treated effluent that will be feed water for the new ATTP. The data needs to be considered in the context of:

• monitoring locations and how water quality can change between locations, • monitoring techniques, • how water quality is analysed, • changes to sewage quality within the period covered by the data set, and • changes to the treatment plant over time.

The majority of the data used to develop the secondary effluent quality statistics was derived from sampling at the following locations:

1. Secondary effluent samples taken from the secondary effluent conduit immediately downstream of clarifiers.

2. Forebay effluent samples immediately upstream of chlorination and the OPS. The Forebay is the first of the EHBs and has a theoretical retention time of 12 hours at average dry weather flow downstream of the secondary effluent sample point described above.

3. Final effluent samples taken from the Outfall Rising Main after addition of chlorine (~ 2 to 3 mg/L as Cl2) and approximately 15 minutes retention time at average dry weather flow.

Water quality is subject to minor changes between the secondary effluent, Forebay and final effluent monitoring points. The principal changes are caused by settlement of residual secondary effluent particulate matter (and re-suspension by strong winds) and chlorination. For each parameter, data deemed to be most representative of the ATTP feed have been presented.


2.3.2 Indicative feed water quality

Secondary effluent quality has been monitored intensively in support of the Tertiary Technology Trials since January 2008 and this recent monitoring period captures changes in secondary effluent quality associated with the implementation of the Ammonia Reduction Project. The feed water quality design basis for the new ATTP, presented in Table 2.1 below, addresses the key water quality parameters relevant to the proposed ATTP process and represents a combination of the long term data set and more recent intensive monitoring program. A more extensive detailed historical set of ETP effluent quality parameters based on longer term data is provided in Appendix A.

Table 2.1 ATTP feed water quality design basis

Parameter 10th Percentile Median 90th Percentile UVT (cm-1, 254nm) 35 42 48 True Colour (Pt-Co units) 70 90 120 TSS (mg/L) 6 15 30 Turbidity (NTU) 3 6 15 COD (mg/L) 40 55 75 CBOD5 (mg/L) 3 6 14 Ammonia-N (mg/L) 1 3 7 Nitrite-N (mg/L) 0.1 0.6 0.8 Nitrate-N (mg/L) 6 11 16 Total-N (mg/L N/S(1) 17 N/S(1) pH 7.1 7.4 7.6 Alkalinity (mg/L as CaCO3) 60 85 105 Total Phosphorus (mg/L) 5 7 10 Anionic surfactants (MBAS, mg/L) 0.1 0.2 0.4 Oil & Grease (mg/L) - <5 16

Notes: (1) NS = None Stated. Total-N 10th and 90th percentile concentrations are not relevant to the ATTP design basis


2.3.3 Forms of nitrogen, pH and alkalinity

The activated sludge plant at ETP was upgraded and reconfigured between late 2005 and late 2007 to allow for nitrification and denitrification to reduce ammonia in the final effluent. As a result the secondary effluent NH3-N, NO2-N, NO3-N, TN, pH and alkalinity have all changed significantly relative to historical data. The data presented in Table 2.1 above is only taken from the period January 2008 through to March 2009 representing the operational period of the activated sludge plant in nitrification/ denitrification mode to date. Starting in early 2010, the Ammonia Reduction Project will be completed and four new aeration tanks commissioned to meet the EPA Victoria discharge licence condition of a 90th percentile ammonia nitrogen limit of 10 mg/L under the full range of annual flow and load conditions. It is possible that secondary effluent NH3-N, NO2-N, NO3-N, TN, pH and alkalinity might change slightly following commissioning of the four new aeration tanks. Since February 2008 the quality of Forebay effluent has been monitored comprehensively at the Tertiary Trials Plant.


3 Advanced Tertiary Treatment Plant

3.1 Process overview

A high level description of the general components of the proposed ATTP is provided below. A more detailed description of each of the process units is provided in subsequent sections of this report. The overall ATTP process is described by the process flow diagram and accompanying mass balance (drawing J46-01-204) included in Attachment B. ATTP feedwater management: The design will provide flexibility allowing the ATTP to receive feed flows either from the EHBs (normal operation) or directly from the Secondary Effluent Channel downstream of the secondary clarifiers. The opportunity to select the best feed water quality for the ATTP facilitates optimum plant operation, throughput and efficiencies. Tertiary supply pump station: The ATTP is being inserted between the existing EHBs and OPS and the hydraulic grade between these two assets is only sufficient to facilitate that transfer. Therefore, a pump station is required to lift secondary effluent from the Forebay into the ATTP and ultimately deliver treated water to the OPS. Ozone dosing; Ozone will be employed to provide a number of treatment functions as follows:

• reduce and improve the aesthetic parameters colour, odour and foam • increase the UVT to enable more efficient downstream UV disinfection • reduce pathogen concentrations (i.e. disinfect) of each of protozoa, viruses and

bacteria • oxygenate the flow ahead of the biological media filters (BMF) to support

biological treatment in that process • microflocculate particulate matter in the feed water to improve downstream BMF

filtration performance. Ozone off-gas will be collected and destructed to oxygen prior to discharge to the atmosphere. Biological media filters (BMF): These are deep bed downflow granular media filters primarily comprising either granular activated carbon or anthracite media with a sand layer underneath. The filtration process removes particulate matter from the water. In addition, due to the prevailing process conditions a biological population of


microorganisms (biomass) 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. UV disinfection: UV treatment will provide pathogen reduction, specifically targeting protozoa (Cryptosporidium) and bacteria. Chlorine disinfection: Chlorine treatment will also provide pathogen reduction, particularly virus and bacteria reduction, and a low disinfectant residual in the final treated 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. The chlorine system will be capable of operating in both free chlorine and combined chlorine (chloramine) disinfection modes. Treated water storage: The storage will provide a fixed volume contact basin for chlorine disinfection Ct requirements. The storage will also provide balancing of flows between the ATTP and the OPS for smooth ramping up and down of flows. Outfall pump station: This pump station is an existing asset and includes 3 duty and 2 standby pumps. The OPS capacity sets the flow requirements for the ATTP. The level of the OPS pumps also provides the fixed end level for the ATTP hydraulic profile. Residuals handling: Regular backwashing of the filters will produce a residuals stream which contains the solids removed from the secondary effluent feed water stream. The backwash stream will be flow-balanced and fed at a steady rate to a dissolved air flotation thickening (DAFT) process. Polymer and ACH coagulant will be used to improve DAFT performance. Clarified water from the DAFT will be returned to the Forebay upstream of the ATTP for re-treatment while the thickened residual solids will be fed to the existing anaerobic sludge digestion process. Alkalinity correction: It is expected that some form of alkalinity and/or pH correction will be required to address the reduction in alkalinity caused by nitrification in the BMF process. At this stage of design, it is proposed to provide hydrated lime dosing. Lime dosing is not expected to be a routine operation and its requirement is dependent on a number of factors as discussed in Section 5.9. 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. Control system: The ATTP control system will integrate with the existing ETP Siemens PCS7 system and be controlled from the existing Eastern Control Centre with provision for local control as required.


3.2 Treated water quality

The ETP currently includes primary settlement and the biological activated sludge process to produce secondary treated effluent. With the implementation of the ATTP, the treated water quality will be significantly improved in terms of physio-chemical and aesthetic parameters, and pathogen reduction. Both the current EPA Victoria licence requirements for ETP final effluent and the anticipated treated water quality from the ATTP are presented in Table 3.1 below, including parameters which are relevant to the Tertiary Upgrade Project but which are not currently licenced. Furthermore, the primary treated water quality benefits associated with the ATTP are outlined below. The ATTP will remove all litter from the effluent, and will reduce fat, oil and grease and reduce the formation and quantity of fat balls. It will also remove suspended solids, Apparent Colour and True Colour, bringing the colour of the treated water down towards drinking water levels. This level of treatment will address the risk of discharge plume visibility at Boags Rocks where the ETP final effluent is currently discharged. Other contributors to plume visibility such as biological foam and surfactants will also be comprehensively addressed. The ATTP will both reduce odour levels and improve the character of the odour in the treated water; the ‘earthy’ odour typical of the ETP secondary effluent will be improved to a more neutral odour that will be less likely to be offensive. The ATTP will also remove all activated sludge plant foam as well as reduce any residual foam forming potential to a level comparable to drinking water. The toxicity of the discharge at Boags Rocks will be further reduced through a combination of further reduced ammonia levels and reduction in any minor toxic components of the ETP effluent other than ammonia. The ATTP will treat all effluent flows to a high microbiological standard which will provide the following benefits:

• Further reinforcement of the "very good" microbiological water quality classification in the vicinity of the outfall and lead to year-round most favourable rating of local bathing water quality under the Draft WHO Recreational Water Guidelines

• Creation of a high quality fit-for-purpose recycled water resource in accordance with the Australian Guidelines for Water Recycling(AGWR)1.

1 National Guidelines for Water Recycling: Managing Health and Environmental Risks. Natural Resource Management Ministerial Council, Environment Protection and Heritage Council, Australian Health Minister’s Conference. November 2006


The projected performance of the ATTP with respect to metals, including the licenced metals chromium, lead, copper and cadmium, is expected to improve in comparison to current treated effluent quality but this is not readily quantifiable as the concentrations of metals are already very low.

Table 3.1 Existing licence conditions for discharge to water and projected ATTP performance

Existing Licence Conditions (1)

Projected ATTP Performance

Performance Indicator, Unit

Med

ian,

A

nnua

l

90th

%ile

A

nnua

l

Max

imum

Med

ian,

A

nnua

l

90th

%ile

A

nnua

l

Max

imum

Comments

Carbonaceous biochemical oxygen demand, CBOD5 milligrams per litre

20 40 NS NS 10 NS

Suspended solids, milligrams per litre 30 60 NS 2 5 NS

Ammonia as nitrogen, milligrams per litre

5 10(2) NS 0.5 2 NS

Anionic surfactants, milligrams per litre

0.4 0.7 NS NS 0.3 NS

E.coli bacteria, organisms/100 mL 200 1000 NS NS 10 NS Recycled water requirements may differ

Turbidity, NTU NS NS NS NS 2 NS Not currently licenced

True Colour, Pt-Co NS NS NS 15 25 NS Not currently licenced Notes: (1) As sampled at the Truemans Road sampling point (2) The 90th percentile ammonia limit comes into effect as of 1 July 2010 NS – Not Stated.


3.3 Design flows

3.3.1 Existing flows

ETP treats an annual average flow (AAF) of approximately 330 ML/d as delivered by the South-Eastern, Chelsea-Frankston and Dandenong Valley Trunk Sewers. This is based on the last three years’ data and is reduced from historical flows by the water saving measures currently in operation as discussed in Section 2.2. Flows within the plant are affected by internal recycle flows and waste flows. The peak wet weather flow (PWWF) to the ETP is 20.4 kL/s (1,750 ML/d), which is the capacity of the Inlet Pump Station (IPS). This entire flow is treated within the primary and secondary processes of the plant. All treated effluent is discharged from site by the OPS. The OPS pumps operate at fixed speeds and therefore OPS output is subject to step changes in flows as outlined in Table 3.2 below.

Table 3.2 Current OPS flow capacity

Operating Scenario Design Output Flow (kL/s) (ML/d) One Pump 3.6 311 Two Pumps 6.6 570 Three Pumps (maximum) 8.2 708

The treated effluent flow through the OPS is currently approximately 380 ML/d, based on an average annual flow of 330 ML/d into ETP plus up to 50 ML/d (0.60 kL/s) of recycled service water, referred to as ‘2W’ and ‘3W’ flow streams, which is currently taken from the rising main downstream of the OPS and used on the ETP site. Plant flows in excess of the OPS capacity are stored in the EHBs which perform a critical function to balance diurnal flow variations and wet weather flows described as follows:

• During average conditions plant flows are normally managed on a daily basis such that the daily discharge from the OPS matches the plant inflow.

• When a significant wet weather event occurs, the flow from the OPS is increased as required up to its maximum of 8.2 kL/s (708 ML/d) by operating all three pumps and secondary effluent flows in excess of the OPS output are stored in the


EHBs until the wet weather event subsides and the OPS catches up with the reduced plant flows and drains the EHBs.

MWC is committed to undertaking the construction of the Western Effluent Holding Basin (WEHB) which will significantly increase the wet weather management capacity of the ETP site and will be in place by the time the ATTP is commissioned. Between the WEHB project and the relatively flat flow growth forecast to the ETP, it is unlikely that there will be significant increase in the capacity of the OPS or the proposed ATTP. However, the concept design of the ATTP also considers how its future output could be increased to match the flow of four OPS pumps (864 ML/d or 10.0 kL/s). The proposed plant layout facilitates future upgrades to the ATTP to make allowance for possible future flow requirements.

3.3.2 Design capacity

The ATTP production capacity will be designed to meet the capacity of the OPS plus any internal recycle flows, and will generally match the capacity of the OPS from minimum (one OPS pump running = 3.6 kL/s) to maximum flow (three OPS pumps running = 8.2 kL/s). MWC has identified the future possibility of providing a new service water pump station which would draw flows from upstream of the OPS. This would potentially increase the peak throughput requirement for the ATTP. It is expected that a new service water pump station would only be implemented for reasons such as asset management and/or operational preferences within the next 20 years rather than to increase peak effluent discharge rates. It is proposed that the ATTP provide treatment capacity for the current OPS and service water configuration, and provide hydraulic capacity for the current OPS and possible future new service water pump station. The proposed design flow capacities for the ATTP are presented in Table 3.3.

Table 3.3 ATTP design flow capacity

Scenario Design Flow (kL/s) (ML/d) Minimum output (commissioning and maintenance) 1.5 130 Minimum output (normal operation) 2.9 250 Maximum output (dry wether flow) 6.6 570 Maximum output (process units) 8.2 708 Maximum output (civil structure hydraulics / piping) 8.8 758


4 Site layout and constraints

4.1 Plant location

ETP is located on a 1,000 hectare site in Bangholme. Access to the plant is from Thompsons Road. Future planning for the site allows augmentation, to deal with increasing loads or changed effluent quality requirements, of the primary and secondary areas to the eastern side of the plant and future expansion of the digesters north and south of the existing digesters towards the eastern end of the digester block. The area between the existing digesters and the Southern Effluent Holding Basin (SEHB) and north towards to the EHBs has been identified for the ATTP and is within close proximity to tie in points in the existing plant.

The location and plant layout is shown in the conceptual view and outline layout drawings in Appendix B. The 1:100 year flood encroaches onto the southern side of the site to a level of 3.2 m AHD. The ground level in the proposed location varies from 3.0m to 4.5m AHD. Consequently only minimal fill would be required to ensure that all structures are above the flood level.

4.2 Plant layout considerations

The ETP is a large and complex facility which is in continuous operation and the ATTP will be a significant augmentation to the site and will require high levels of system integration. While the majority of the ATTP will be located in essentially a vacant brownfield area of the site, implementation of the ATTP must be carefully planned, designed, constructed and commissioned while maintaining full ETP plant performance and licence compliance. In terms of layout and interface considerations, the key assets and services which the ATTP impacts on include the following:

• Forebay, EHB system and Tertiary Supply Pump Station (TSPS): Secondary effluent is to be supplied from the EHBs to the new TSPS. This interface has been designed to minimise interference with the EHBs during construction.

• Secondary effluent channel and TSPS: Provision to supply secondary effluent directly to the TSPS will be provided in addition to being able to supply from the Forebay. To feed secondary effluent directly to the TSPS the existing


mechanical effluent screens, as distinct from the 3mm aperture static screens, will be removed as they will be redundant after the construction of the ATTP. The new feed channel tie-ins will need to be managed to ensure that the OPS and Forebay remain operational. The Forebay can be isolated during construction of the channel.

• Outfall Rising Main: The 2.1m diameter pipeline (also referred to as the South Eastern Outfall or SEO) will have to be traversed twice – once to supply feed water to the ATTP and once to return final treated water to the OPS.

• Chlorination system: The existing chlorination system is to be retained and upgraded to ensure that required chlorine dose rate and disinfection requirements for the ATTP can be met. The connections will need to be performed to ensure that the existing chlorination is not compromised. The ATTP must also be implemented in accordance with ETPs Major Hazard Facility classification.

• Treated Water Storage (TWS) tie-in with the OPS: The outlet of the TWS is to be connected to the existing OPS for the off-site discharge of final treated water. This connection will comprise a large buried pipeline passing through areas with existing services including the Outfall Rising Main. The construction of the tie-ins will need to be managed to ensure that the OPS remains operational.

• Chelsea-Frankston Sewer: This delivers sewage to the head of ETP and may be used for emergency residual stream discharges from the ATTP.

• EHB system and Southern Effluent Holding Basin (SEHB): Tie-ins are required for ATTP recycle stream returns, clean stormwater runoff, and emergency overflow provisions.

• ATTP residuals and anaerobic digesters: The ATTP residual solids handling system will be tied-in with the existing heat recovery hot water and anaerobic sludge digestion systems. The connections will be performed to ensure that the existing sludge heating and digestion systems remain operational.

• Control system interfaces: The ATTP automated control system will be configured to be operated by the site’s main control system.

• High Voltage power supply: The ATTP drives the need for a site power supply upgrade as discussed in Section 5.10. It is proposed to investigate opportunities to integrate the new ATTP power supply network with certain areas of the existing ETP, such as the OPS, to provide enhancements to overall site power supply reliability and availability. The construction of the tie-ins will need to be managed to ensure that all relevant systems remain operational. In addition, there is an existing 6.6 kV duct bank feed power supply to a substation located at the Surge Vessels which impacts on plant layout.

• Site services: General site service connections such as potable water, service water, compressed air, roadways and surface water drainage, ventilation and lighting, fire alarm and suppression systems, tunnels/galleries, 415V emergency power, plant cathodic protection system, and security, PA and telephone systems.


In addition, the ATTP project must coordinate carefully with other major works occurring at ETP at same time. Where possible, new services and pipelines will cross above the Outfall Rising Main and the Chelsea-Frankston Sewer to minimise risks of damaging these critical services during construction. The exception to this is the TWS discharge pipeline to the OPS. For hydraulic gradient reasons this has to pass under the Outfall Rising Main. Emergency overflows from the BMF system and the TWS are routed above ground to pass over the Outfall Rising Main. These lines will pass under the existing SEHB bund/road prior to discharge into the east side of the SEHB. The following conditions have also been applied in deriving the preferred ATTP layout:

• Segregation of treated water and secondary effluent is essential to address potential recontamination risks. Air gap separation is provided where possible.

• Permanent roads and hardstanding areas for maintenance will be provided to the new ATTP plant area as an extension of the existing road system. These roads will be capable of carrying all vehicles requiring access to the ATTP. – Concrete walkways matching existing will be provided for access to new

facilities. – Hardstanding areas will be provided to allow the set up of mobile cranes for

lifting major equipment, meeting similar requirements as the roads. • Clean storm water drainage will flow into the SEHB. Any areas within the

ATTP which could experience contamination, such as loading bays, chemical storage areas, etc, will be bunded separately from the stormwater system and discharged in a controlled manner to the head of ETP via the existing sewers. The hard surface runoff from the ATTP (roads and roofs) will have no measurable impact on basin flows.

• Construction of structures over the Chelsea-Frankston Sewer or SEO or loading via the angle of repose above the pipe centre line is to be avoided.

4.3 Materials of construction

The materials of construction for the ATTP may be summarised as follows:

• TSPS: Concrete pump station • Ozone building: Concrete tilt panel walls with steel roof • Other buildings and switchrooms: Concrete tilt panel walls with steel roof, or

open sided structures with steel roof • Ozone contactors: 316 stainless steel pipe work


• BMF system: Concrete open tank construction with pump and blower building, consisting of steel roof and precast concrete panel walls

• UV disinfection system: Concrete channels (for open channel configuration) and building on upper story, consisting of steel roof and precast concrete panel walls

• TWS: Earthen embankment construction with membrane lining and covers • General plant tankage: Concrete construction.

Concrete will typically be used for main tankage due to their large size. Buildings will typically be designed and constructed with concrete tilt panel walls and steel roofs to suit existing ETP architecture. Large process pipes will typically be steel with epoxy lining except for the ozone contactors which will be stainless steel as they are in direct contact with ozone. Emergency overflow pipes will be concrete unless they contain numerous bends in which case epoxy-lined steel is more economical.

4.4 Hydraulic considerations

Hydraulics played a key role in determining the ATTP site layout as well as its structural requirements. Two major factors that influence the hydraulics are:

• Suction requirements for the OPS pumps: As the OPS will continue to be used to discharge treated water off-site, the hydraulic requirements of these pumps set the hydraulics through the ATTP.

• The site topography: The existing ground level for the ATTP is at a similar level to the required minimum water level at the inlet to the OPS (3.3m AHD) and is generally flat. Two options were evaluated in terms of general approach to hydraulic design for the ATTP:

– Option 1: Provide the necessary plant hydraulic grade by lifting once at TSPS to enable gravity flow through the remainder of the plant. This results in the structures of the BMF system and UV disinfection system being elevated above ground level.

– Option 2: Provide a moderate lift at the TSPS and subsequently providing a re-lift pump station between the UV disinfection system and the TWS. This results in the BMF and UV structures being either slightly sunken in the ground or at grade level.

Option 1 has been adopted as this stage as it is more robust hydraulically and less complicated than having to pump the water twice as required for Option 2. The preferred approach will be further reviewed, refined and confirmed as part of subsequent design activities.


A hydraulic profile of the proposed ATTP design is provided in Appendix B. The BMF backwash balancing tank is the deepest structure within the ATTP. This tank will be located to receive gravity discharge of backwash water from the BMF. At locations within the ATTP where flow can be isolated downstream of an open channel, overflow systems will be provided to prevent overtopping of channels and ensure controlled flow management.

4.5 Geotechnical considerations

The results of geotechnical investigations at the proposed site are summarised in Table 4.2 below. Based on this information heavy (water-retaining) structures founded at existing ground level or on additional fill will require any existing soft fill material and some of the unconsolidated peaty clay soils to be removed and replaced with compacted selected fill prior to construction to minimise settlement. Where necessary preloading of foundations may also be used to reduce settlement. However, it is not envisioned that any structure will require piling foundations.

Table 4.2 Geotechnical summary

Soil description

Fill deposits (1m - 2.7m thick) overlaying Quaternary age sediments, comprising peaty clay and clay formed from swamp deposits overlaying clayey sand from the Brighton Group Sands formations.

Bearing capacity

CBR for roads 2.5 Design bearing at typical formation 0m – 1m AHD (eg below fill material) = 100KPA

Ground water -0.63 to 1.93m AHD

Permeability Sump pumps in excavations should be sufficient for dewatering excavations to 0m AHD

Max excavation slope Up to 70deg from horizontal

Typical ground level 3.0 - 4.5m AHD


5 Process units

5.1 ATTP feed water management

Provision will be made to supply secondary effluent to the ATTP either from the Forebay or from the Secondary Effluent Channel prior to the Forebay to provide a feed water selection option for the ATTP. During normal operation the Forebay provides some effluent polishing prior to chlorination and off-site discharge by the OPS. However, under certain conditions such as high wind events, settled particulate matter can be re-suspended in the Forebay. It is proposed that at times when the effluent from the Secondary Effluent Channel is of better quality than that from the EHBs the feed to the ATTP should be taken directly from the Secondary Effluent Channel to optimise ATTP performance. The benefit of such a provision has been demonstrated through the Tertiary Technology Trials. This alternative supply provision will be achieved by the construction of a new concrete channel between the Secondary Effluent Channel and the EHB Return Channel west of the OPS. The channel will be hydraulically sized for the peak flow to the ATTP and the balance of any wet weather flow that exceeds this will pass through the Forebay to the other holding basins. The new channel structure will be controlled with gates to allow the source of the feed to the ATTP to be switched between either the Forebay outlet or the Secondary Effluent Channel prior to the Forebay.

5.2 Tertiary Supply Pump Station

The TSPS is required to supply secondary effluent feed water to the ATTP. This pump station will provide all the hydraulic head for flow through the ATTP to the OPS. The capacity of the pump station is based on the peak flow requirement as set out in Section 3.3.2 including filter washwater and process recycle allowances. Refer to the process flow diagram in Appendix B for further detail. Design parameters for the TSPS are presented in Table 5.1 below.


Table 5.1 Tertiary Supply Pump Station design basis

Design Parameter Units Size Maximum influent flow ML/d 810 No. of pumps operating at max design flow No. 5 No of standby pumps at max design flow No. 2 Design flow per pump m3/h 6,750 Max pumping head m 13m Motor size kW 450 Pump control - Variable speed

The maximum pump station flow for the proposed process design is 760 ML/d. However, it is proposed to provide an increased feed flow of 810 ML/d to provide the flexibility to facilitate future augmentation of the plant, as discussed further in Section 8, which would increase internal recycle flows. Provision of this additional capacity has no notable impact on pump station design and cost as the pump head drives the design basis rather than flow. Furthermore, incremental augmentation once the pump station is constructed would incur increased complexity without offering any quantifiable staging benefits. Variable speed drives are proposed to allow a smooth transition of flows to the ATTP and allow fine process control. It is expected that the pump station will generally be operated to match the operation of the OPS, although there is hydraulic buffer capacity in the TWS under average conditions to allow the TSPS to run at a constant flow while the OPS flow changes between one and two pump output. The flow will be transferred from the pump station in two equally sized pipelines which include flow meters. It is intended that either pipeline can be isolated for maintenance. Secondary effluent feed flow from the activated sludge plant to the TSPS will be balanced in the EHBs. There is sufficient storage volume in these basins to allow ATTP flows to be relatively independent of the ETP flows, including operation to facilitate treatment efficiency and use of off peak power tariffs under dry weather conditions.


5.3 Ozone treatment

5.3.1 Description

Ozone will be used in the ATTP to provide the following benefits:

• Reduce colour, odour, and foam formation potential • Increase effluent UVT • Provide pathogen reduction (disinfection) • Oxygenate feed to the downstream BMF process to support nitrification • Provide microflocculation of particulate matter

The design and sizing of the ozone system is primarily determined by the colour reduction and pathogen reduction requirements, with the other functions being met incidentally.

5.3.2 Ozone system design basis

Ozone will be generated from oxygen using on-site ozone generation equipment. The oxygen supply to the ozone generators will come from two sources. The primary oxygen supply will be a Vacuum Pressure Swing Adsorption (VPSA) system which will provide the base load to the generators (normal dry weather operating flows). The VPSA supply will be supplemented by liquid oxygen (LOx) supplied from a bulk onsite storage facility. The LOx system will provide additional oxygen to allow ozone production to be increased under peak conditions. The LOx system also provides standby capacity to the VPSA system allowing maintenance to be carried out on the VPSA system without interruption to plant operation. The VPSA system, ozone generators and LOx control systems will be housed within a building. The LOx tanks and vapourisers will be located in a fenced yard adjacent to the building. The design of the ozone system, comprising integrated oxygen supply and ozone generation, is complex and therefore there is scope for design optimisation to deliver the lowest whole-of-life costs. The concept design presented in this report is based on preliminary optimisation studies to date and it is possible that the approach will be refined as part of subsequent design activities. In particular, details around the ozone generation rate, oxygen supply rate and the distribution between on-site oxygen generation and LOx consumption may change as the design is further developed.


Ozone generation system

The design flow, ozone doses, and resultant production that were used to size the ozone system equipment are listed in Table 5.2. Note that the design flows for the ozone system are higher than the ATTP treated water output at each operating condition due to the additional feed flow required to account for the BMF backwash stream.

Table 5.2 Ozone generation design conditions

Flow (ML/d) Condition ATTP output

Ozone system

Transferred ozone dose

(mg/L)

Ozone demand (kg/hr)

One OPS pump 311 324 10 135 Annual average 380 400 10 165 Two OPS pumps 570 606 10 250 Three OPS pumps 708 744 8 250

The ozone doses in Table 5.2 have been derived from the Tertiary Technology Trials, and refer to effectively transferred ozone doses as compared to applied doses which are subject to transfer efficiency considerations. One and two OPS pump flow conditions are typically associated with dry weather flow conditions at ETP. A reduced dose for the three OPS pump flow condition is applicable as this flow condition is associated with wet weather flow to the ETP in which case the contaminants (such as colour) in the effluent are generally diluted by the increased flow. Consequently, the same total amount of ozone is required to treat the two and three OPS pump flow conditions. Furthermore, ozone production can be temporarily increased above the design production rate if required as discussed further below. The ozone system will be sized on the basis of producing ozone gas from oxygen at 10 percent ozone by weight (wt%). There is a balance between optimal capital and operating cost and design ozone gas concentration for oxygen-fed ozone systems. Operating at higher ozone gas concentrations reduces the oxygen feed gas system costs but generally increases the ozone generation plant costs because the specific energy (kWh/kg ozone) required to produce the ozone increases. In contrast, operating at lower ozone gas concentration substantially increases amount of oxygen gas used but lowers the ozone generation plant costs. Preliminary studies have suggested that the optimal ozone gas concentration for the ATTP is 10 wt% ozone. However further review will be undertaken during subsequent design development and refinement activities. A feature of designing on the basis of 10 wt% ozone is that the output of an ozone generator can be boosted by up to 30% by


increasing the oxygen feed gas rate and dropping the ozone gas concentration down to 6-7 wt%. This feature will be incorporated into the system and therefore provides both redundancy above and beyond the allowance of a standby ozone generator and increased ozone production in the event of high load conditions. Another consideration in the design of the ozone system is how effectively the ozone will be transferred to the process flow stream. The ozone quantities presented in Table 5.2 above are effectively applied quantities and the actual ozone production rate must be higher to account for transfer efficiency. The transfer efficiency of the proposed ozone injection system is very high at around 96% and therefore has only a minor impact on ozone production rate requirements. A summary of the ozone system design basis is provided in Table 5.3.

Table 5.3 Ozone system design basis

Description Units Value Required applied ozone mass rate kg/hr 250 (refer Table 5.2) Ozone transfer efficiency % 96% Required ozone production rate kg/hr 260 Design ozone gas concentration wt% 10 Adopted ozone generator capacity at design ozone gas concentration, (each)

kg/hr 66

No. of generators No. 5 (4-duty / 1-standby) Actual ozone production capacity at design concentration

kg/hr 264 at 10 wt% ozone

Individual ozone generator capacity at varying ozone gas concentrations

- 66 kg/hr at 10 wt% ozone 72 kg/hr at 9 wt% (range 69 – 75) 78 kg/hr at 8 wt% (range 73 – 83) 83 kg/hr at 7 wt% (range 75 – 91) 87 kg/hr at 6 wt% (range 77 – 96)

Design ozone gas flow condition: - ozone production rate (max.) - total gas flow rate (i.e. ozone/oxygen)

- -

330 kg/hr at 10 wt% ozone

3,300 kg/hr


Oxygen supply system - generation & LOx

The estimated range of oxygen feed gas consumption rates for ozone generation is presented in Table 5.4. The total oxygen feed gas requirement will be met through a combination of on-site generation and onsite LOx storage.

Table 5.4 Estimated oxygen consumption rates for ozone generation

Description Units Minimum Average Maximum Design case - 1 OPS pump flow

10wt% ozone average annual flow

10wt% ozone 3 OPS pump flow

10wt% ozone Oxygen consumption tonnes/d 34 42 78

Oxygen will be generated from air by a VPSA oxygen plant. VPSA plants generally perform most efficiently when operated within a specific range of their design capacity. Sizing one VPSA plant for the maximum oxygen consumption rate would present turndown problems to achieve the minimum rate and lead to the requirement for two VPSA plants at 50% of the maximum rate. Alternatively, the VPSA plant can be sized at less than the maximum consumption rate with the balance met by LOx. The relative contribution from each oxygen source impacts on a range of considerations including capital cost, operating cost, energy consumption, reliability and availability, and LOx truck deliveries. Based on consideration of feasible plant operating regimes and preliminary whole of life analyses, the expected capacity of the VPSA plant is from 34 to 50 tonnes/d. The specific sizing of the VPSA plant will be reviewed through the course of subsequent design development and optimisation activities and is dependent on the overall plant operational philosophy to achieve lowest whole of life costs and address environmental considerations. Given that oxygen generation plants produce oxygen-rich product gas from atmospheric air, the by-product of oxygen generation is predominantly nitrogen that has been removed from the air feed gas (air is 21% oxygen and 79% nitrogen with some trace gases). Additional oxygen supply required to meet ozone generation requirements beyond that met by the VPSA plant will be provided from an onsite LOx system. The LOx system also provides redundancy at times when the VPSA plant is unavailable, such as during routine maintenance tasks or unplanned outage.


The LOx system comprises bulk cryogenic storage, vapourisers and flow control systems. The key design features of the LOx system are the storage capacity and number of days between tanker deliveries, and the capacity of the vaporiser and gas flow control systems. During normal operation the LOx system will supply any oxygen required in excess of the VPSA output to meet the ozone generation rate. The LOx system, including the vaporiser and gas flow control systems with complete modulated turndown, will be sized to meet the maximum oxygen consumption rate of 78 tonnes/d in the event of the VPSA being unavailable. The proposed LOx storage capacity is presented in Table 5.5.

Table 5.5 LOx design basis

Description Units Value No. of LOx storage vessels No. 3 Capacity per vessel (each) L 64,000 Total storage provided L 192,000 Size of LOx truck delivery L 15,000

This design basis provides for the following scenarios:

• Based on the lower bound VPSA plant capacity of 34 tonnes/d: – Given that this VPSA plant capacity is less than the estimated average

oxygen consumption rate of 42 tonnes/d, LOx would be used on a routine basis to make up the difference. The annual average LOx consumption would be around 8 tonnes/d or 2,900 tonnes/yr, and would require around three 15,000 L LOx tanker deliveries per week, or 150 deliveries a year.

– At average loading conditions with the VPSA in operation there would be around 23 days LOx storage with no deliveries.

– There would be the ability to maintain operation at average flow conditions with the VPSA out of service and operating on LOx alone for 4 days with no LOx deliveries, and 7 days with one LOx delivery per day. The plant could maintain operation at peak conditions with the VPSA out of service and operating on LOx alone for around 3 days with one LOx delivery per day.

• Based on the upper bound VPSA plant capacity of 50 tonnes/d: – Given that this VPSA plant capacity is greater than the average oxygen

consumption rate of 42 tonnes/d, LOx would not be required on a routine basis depending on the operational philosophy of the ATTP and its flow rate relative to the OPS flow rate. Rather, LOx would only be used when the oxygen consumption rate exceeded 50 tonnes/d and this is estimated to be


<25% of the time. The annual average LOx consumption would be around 700 to 1,500 tonnes/yr, and would require around 40 to 90 deliveries a year.

– At average loading conditions with the VPSA in operation there would be no demand on LOx storage if the ATTP is operated at a constant flow rate.

– The ability to maintain operation with the VPSA out of service and operating on LOx alone would be the same as described in the case of the 34 tonnes/d VPSA plant.

From the above scenarios it is evident that a larger VPSA plant capacity provides the opportunity to reduce LOx consumption. Considering that using oxygen from LOx produced off-site is typically more expensive than that produced from an on-site VPSA plant, the increase in capital costs for a larger VPSA plant can be offset by cost savings of not using LOx. Further to costs, the whole of life analysis to be undertaken as part of subsequent design development activities to determine the preferred VPSA plant capacity will also consider environmental considerations including greenhouse impacts and truck movements.

Ozone plant cooling system

The ozone generation process results in the production of significant amounts of heat and the generators operate most efficiently at low temperatures. A cooling system is therefore required and it is currently proposed to provide a cooling water system comprising the following elements:

1. A closed loop cooling water circuit between the ozone generators and the heat exchangers including a circulation pump station.

2. An open loop cooling water circuit including a supply pump station to and from the heat exchangers.

The closed loop side will be potable or deionised water with appropriate treatments and the open loop side will be a once through system utilising product water from the ATTP. Double plate and frame heat exchangers will be used to keep the closed and open loop streams completely separate. The open loop cooling water will be drawn from the TWS discharge pipe via a submersible pump station and discharged to the same pipe downstream of the pump station and upstream of the OPS. The closed loop flow rate will vary depending on the number of ozone generators in operation, and the open loop flow rate will vary according to the open loop water temperature and system cooling duty. The temperature rise in the open loop cooling water and treated effluent flow will be less than 2˚C and 0.1˚C respectively.


The design basis for the cooling water system is presented in Table 5.6.

Table 5.6 Ozone plant cooling system design basis

Description Units Value Open loop flow (fixed) ML/d 53 Open loop pipe diameter mm 600 No. of open loop supply pumps No. 3 (2-duty, 1-standby) Closed loop flow (max.) ML/d 53 No. of closed loop circulation pumps No. 5 (4-duty, 1-standby) No. of heat exchangers No. 3 Max. cooling system duty (heat load) MW 2.4

The design of the ozone plant cooling system will be reviewed and refined as part of subsequent design activities, including consideration of other cooling system configurations including air-to-water heat exchangers and chillers. Ultimately the specific requirements of the cooling system are dependent on the specific ozone generator supplier selected.

Ozone injection and contactor

The ozone gas will be injected into twin grade 316L stainless steel pipeline contactors to ensure efficient transfer of ozone into the main process flow. The ozone will be consumed rapidly, however a large amount of oxygen gas will remain dissolved/entrained in the water (at 10wt% ozone feed gas concentration, around 90% of the feed gas is oxygen). A side-stream ozone injection system will be used. In this system the ozone is injected into a small portion of the flow to be treated (the “side-stream” flow). The side-stream flow is then re-injected into the main flow using a series of jet nozzles to ensure rapid mixing and dispersion of the ozone. This system allows very high ozone transfer efficiencies, in the order of 96%, to be achieved. The ozone side-stream equipment design basis is presented in the Table 5.7 below.


Table 5.7 Ozone side-stream injection design basis Description Units Value No. of side-stream trains No. 7 (6-duty, 1-standby) No. of injectors and motive water pumps per train No. 1 Injector water inlet pressure kPa(g) 35 Motive water pump flow (each train) m3/hr 232 Motive water pump head (each train) m 38 Side-stream flow as a percentage of main process flow % 4-6 Max. total power rating (motive water pumps) kW 275

The design basis for the ozone contactors is provided in Table 5.8.

Table 5.8 Ozone contactor design basis

Description Units Value Average Annual Flow Peak Flow (future)

Process flow at contactors ML/d 401 810 No. of contactor pipelines No. 2 Contactor diameter (each) m 2.0 Contactor pipe length (each) m 195 Total contactor volume m3 1,404(1) Retention time mins 5 2.5

Notes: (1) includes 224m3 at BMF inlet structure prior to degassing

The ozone contactor pipelines will discharge to an open water surface via stilling chambers at the BMF inlet. This is an enclosed chamber that will allow the release and collection of any entrained gas from the contactors. The chamber will also include water spays to suppress any scum formation caused by the release of the entrained gas. Ozone dosing involves applying large quantities of ozone gas (which is 90% oxygen) and while some of the applied gas will remain in solution in the main process flow most of it will leave the main process flow once it exits the contactor pipelines. It is expected that there will normally be no significant ozone residual at the end of the ozone contactors. However, some residual ozone gas may remain unreacted and therefore any off-gas will be collected and treated to ensure safe discharge to the atmosphere.


Ozone destruction system

The off-gas pressure in the BMF inlet chamber headspace will be controlled and off-gas conveyed to the ozone destruction units. The residual ozone in the off-gas is destructed by a thermal catalytic reaction which simply speeds up the natural decay of ozone to oxygen. The ozone destruction units will consist of a preheater, catalyst bed, and fan. The ozone destruction system will be sized to treat the maximum gas flow rate with up to 1 wt% ozone, and there will be one destruction unit for each ozone generator because turndown of fans or compressors is less than the turndown of generating equipment. The design basis for the ozone destruction system is listed in Table 5.9.

Table 5.9 Ozone destruction system design basis

Description Units Value Maximum inlet gas concentration wt% 1.0 No. of destruction units No. 5 (4-duty, 1-standby) Off-gas destruction capacity kg/hr 3,300 tonnes/d 79

5.4 Biological media filtration

5.4.1 Description

Downstream of ozonation, the water is filtered by means of gravity down-flow deep bed granular media filtration. Due to a combination of the composition of the effluent and the effects of ozonation, a biological population (or biomass) will develop on the filter media and therefore they are referred to as biological media filters (BMF). The BMF process provides the following treatment functions:

• Removal of particulate matter through media filtration to reduce effluent solids and turbidity, and facilitate more efficient downstream disinfection stages and more efficient operation of any future membrane installation

• Nitrification of ammonia • Biodegradation of dissolved organic material • Removal of foam formers and precursors to fat ball formation


5.4.2 Biological media filtration design basis

Feed water pre-treatment by ozone results in the formation of a fixed-film biomass on the filter media. Typically granular activated carbon (GAC) media is used in conjunction with ozone pre-treatment and the development of biomass means it is generally 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 GAC is anthracite filtration media, which does not have the same pore structure or surface adsorption properties but has been trialled alongside GAC and was found to offer comparable treatment performance while potentially offering some advantages at full-scale. At this stage the functionality of both media types appears similar and a final choice will be made based on further investigation and design work. In recognition of this, the generic term biological media filtration (BMF) which covers both GAC and anthracite media is subsequently used instead of BAC. The filters will treat design flows at a peak filtration rate of up to 12 m/h with three filters offline (either due to backwashing, maintenance or unplanned equipment failure). This peak filtration rate is consistent with best practice approaches to drinking water and recycled water media filtration applications. Provision will be made to enable BMF feed flows up to the full design flow to be sent either downstream to UV disinfection or returned upstream of the ATTP for re-treatment in the unlikely event that the whole filtration system is taken out of service. At this stage of design it is proposed to provide the required filter area using 36 filters. However, considering the very large size of this filtration system alternative configurations are being investigated to ensure the optimum configuration is adopted. In addition, a number of different media bed configurations have been investigated through the Tertiary Technology Trials with little to separate them in performance. At this stage it is proposed to adopt a media bed comprising 1.3mm anthracite and 0.6mm sand, although this configuration is subject to optimization through additional pilot testing and detailed design work. Minor variation of the backwash air scour rate and backwash water rise rate may also be adopted as these are dependent on the specific media characteristics. The design basis for the BMF process is presented in Table 5.10 below.


Table 5.10 BMF design basis (nominal(1))

Design Parameter Units Value Max. hydraulic design feed flow ML/d 810 Max. treatment design product flow ML/d 708 Max. headloss m 2.5 No. of filters No. 36 Filter dimensions m 13.2 by 6.0 filter floor area Filter area (per filter) m2 80 Filter area (total) m2 2,850 Media depth m 2.0 Media material and grade - 1.7 m anthracite (size 1.3 + 0.1mm)

0.3 m sand (size 0.6 + 0.1mm) Filtration rate with three filters offline m/h 3xOPS pump design flow (708 MLD): 12 Max. no. of backwashes per day No./d 2 Design backwash bed expansion % 30 Backwash air scour rate m/h 60 Backwash water rise rate m/h 54

Notes: (1) Final choice of media types, sizes and depths will be made based on further investigation and design work. Design finalisation may result in minor changes to other design parameters such as backwash air scour and water rise rate.

Filter arrangement and operation

The ozonated and oxygenated water will enter a common main filter channel that feeds 36 filters, subdivided into 4 banks of 9 filters. The filter block layout includes design elements such as common feed channels to banks of filters with product water following a similar network of channels located underneath the feed channel network.

Each filter will be individually controlled through air operated, automatic filter control valve and outlet flowmeter at their discharge. These will ensure a controlled filtration rate and ensures an even split of flows to each filter. Inlet weirs are not used for filter flow split in order to minimise head loss and to maximise the retention of dissolved oxygen in the ozonated water.

Water for the filter backwash operation will be drawn from a filtered water tank at the filter outlet. A backwash wastewater tank will provide balancing storage for dirty backwash water prior to return for processing. The backwash sequence will consist of air scour, combined air and water washing, and water washing only to maximise solids removal from the bed during cleaning.


A conservative filter maximum filtration rate of up to 12 m/h has been selected with three filters out of service (either two filters backwashing simultaneously and one filter out of service, or one filter in backwash and two filter out of service) at maximum design flow. Under typical average conditions the actual filter loading rate will be significantly lower at around 6 to 7 m/h.

The standard operating methodology will generally involve only a single backwash per day for each filter. Under average flow and load conditions it is anticipated that the filter run time will be approximately 24 hours. In the event of peak secondary effluent solids loads the filter run times may reduce down to 12 hours, equating to an increase in backwash frequency from once per day to a maximum of twice per day.

Each filter will function independently and therefore the non-availability of any given filter will not hinder the operation of other filters.

The filters will be equipped with filter-to-waste functionality to ensure filtered water quality immediately following backwash. This is inline with best practice management for filters in drinking water plants. Three options have been considered to managing the filter-to-waste discharge:

1. Return to the head of the ATTP or to the inlet of the BMF system for re-treatment. This could be achieved by providing a balancing tank and pump system to moderate the flows, and either providing a dedicated pipeline or creating a tie-in with another pipeline and increasing its capacity.

2. Discharge to the BMF spent wash water handling system and ultimately the head of the ATTP for re-treatment. This would require slightly increasing the hydraulic capacity of this system.

3. Discharge to the BMF back wash supply tank to reduce the quantity of in-spec filtered water used for backwashing.

At this stage of design it is proposed to adopt the second option as it maximises product water quality and does not require additional infrastructure.

Filter washing

The filter backwash process is fully automated, and will be initiated by any one of the events listed in Table 5.11 below. A priority queue arrangement will be provided for washing of filters.


Table 5.11 BMF washing events

Wash trigger Description Timer When any filter has been in service for a predetermined time, a filter wash

will be automatically initiated. The in-service time for each filter will be an adjustable timer

High headloss When the pressure drop across the media of any filter reaches a high setpoint, a filter wash will be automatically initiated.

High outlet turbidity When the filtered water turbidity of any filter reaches a pre-determined setpoint, a filter wash will be automatically initiated. The turbidity setpoint will be adjustable.

Manually initiated Manual initiation of filter back wash will also be possible

Filter backwash supply holding tank

The filter backwash holding tank is provided to store clean filtered water needed to backwash the filters. The tank will be reinforced concrete as part of the filter structure. The tank will be equipped with level monitoring instrumentation as part of the control system. The design basis for the BMF backwash supply holding tank is presented in Table 5.12.

Table 5.12 BMF backwash supply holding tank design basis

Design Parameter Units Size No. of tanks No. 1 Tank working volume (each) m3 1,500 No. of backwashes held at peak backwash frequency No. 3(1)

Notes: (1) 1 backwash volume = the water needed to backwash one filter cell

Filter backwash pumps

The filter backwash pumps will be horizontal-mounted dry well centrifugal units. The provision of variable speed motors will allow the backwash regime to be optimised to suit actual performance on site and adjusted to suit seasonal water temperature changes. The pumps will be of sufficient capacity to allow up to 30% expansion and restratification of the bed. The pumps will draw water from the filter backwash supply holding tank. The design basis for the filter backwash pumps is presented in Table 5.13 below.


Table 5.13 BMF backwash pumps design basis (1)

Design Parameter Units Size No. of pumps No. 5 (4 duty , 1 standby) Design head m 15 Design flow (each) m3/h 2,000 Power rating (each) kW 110

Notes: (1) Based on current media selection – minor variations are possible for alternate media choices The backwash pumps and associated air scour blower system will be housed within a building located adjacent to the filter block.

Filter instrumentation

Filter instrumentation required for normal operation and monitoring, including expected HACCP monitoring provisions, include the following:

• Level measurement for level control of each filter • Differential pressure measurement across the filter media beds of each cell for

headloss measurement • Filtered water flow measurement for each filter to control filtration rates • Ability to measure filtered water turbidity for each filter

5.5 UV disinfection system

5.5.1 Description

The UV system provides a disinfection barrier through the inactivation of pathogenic organisms. The UV system is designed to provide a minimum of 4-log inactivation of protozoa (Cryptosporidium) and bacteria (E. coli). The UV system has been based on low pressure, high output (LPHO) UV technology. Both medium pressure and low pressure high output options were investigated. LPHO was determined to be the most suited to this application based on a whole-of-life cost analysis.


The LPHO UV technology selected at this stage of design includes the following features:

• Variable output lamps capable of turndown to 55% of maximum output per bank • Automated Clean-In-Place lamp system to ensure optimum lamp performance • Systems to control UV dose relative to UV transmittance and flow

The UV system may be either open channel system or a closed reactor system. The open channel system requires a free water surface and therefore has to be located at the elevation of the hydraulic grade line. The closed reactor system operates under pressure within a pipe. This means that it can be located below the hydraulic grade line offering greater flexibility in design location. At this stage the concept design is based on an open channel configuration. However, a closed reactor configuration may offer benefits in terms of hydraulic profile and plant layout and therefore the final UV system configuration will be reviewed and confirmed as part of future design development activities. The disinfection performance of either configuration will be identical.

5.5.2 UV system design basis

The filtered water quality resulting from upstream ozone-BMF treatment is suitable for UV disinfection. The filtered water turbidity will typically be around 1 NTU as a median and < 2 NTU as a 90th percentile. Ozone-BMF treatment (predominantly ozone) significantly increases the UV transmittance thereby significantly reducing the specific power required to provide a nominal UV dose. UV disinfection system feedwater UV transmittance will be a key process control parameter. The BMF filtered water will enter a common channel on route to UV disinfection. The exact configuration of the UV system is dependent on the final supplier selection (each supplier has differences in design details) and therefore the design details presented in the following paragraphs are nominal only. The inlet channel to the UV disinfection facility will be designed to provide good flow distribution and consistent feed to the UV system. The flow from each UV channel will flow into a common channel, which continues to the TWS. The nominal design allows for five parallel channels, each channel containing three banks of lamps arranged in series. The final number of channels and UV banks will depend on the UV vendor selected. Each of the open channel bays includes two sets of penstocks. The influent penstock arrangement is for channel bay isolation. The downstream penstock is a modulating weir type which controls flow while providing a constant water


level in the channel bay and ensuring the correct submergence of the UV lamps at all times. The number of banks of lamps operating in each channel can be varied and the power output of each bank of lamps can also be varied. This provides a nominal 6 to 1 turndown per channel allowing optimisation of power consumption. The number of channels and banks of lamps in operation, and the lamp output in each bank will be controlled by an algorithm designed by the UV system supplier to ensure that the design UV dose is achieved. Each module will be able to be readily removed from the bank and replaced without moving or disconnecting the other modules in the bank, or without the need to empty the UV channel. A superstructure will be located directly above the open channel system. The first level of the structure is open, allowing maintenance access and removal of lamp modules. A monorail and hoist are provided for each row of module banks. The UV switch room will be located on the second level of the structure, where the UV ballast panels and UV system distribution board will be located. The nominal design basis for the UV disinfection system is provided in Table 5.14.

Table 5.14 UV disinfection system design basis (nominal(1))

Design Parameter Units Size Design peak flow ML/d 708 Design average flow ML/d 380 Design UV transmittance % 55 Average UV transmittance % 64 Turbidity NTU Typically 1, 90th percentile <2 Target log reduction value (LRV) - 4-LRV protozoa (Cryptosporidium)

4-LRV bacteria (E. Coli) Nominal validated UV dose mJ/cm2 22(2) Lamp type - Low pressure high output Number and dimensions of channels - 5 No. 1.6m deep x 2.9m wide x 15m long Number of banks per channel No. 3 Total no. of lamps No. 3,200 Maximum power kW 800 Flow control device - Modulating weir

Notes: (1) UV disinfection system design is ultimately dependent on the specific UV technology supplier engaged to deliver the system (2) As per USEPA Ultraviolet Disinfection Guidance Manual for the Final Long Term 2 Enhanced Surface Water Treatment Rule, November 2006


5.6 Chlorine disinfection

5.6.1 Description

Chlorine disinfection is the final treatment step of the ATTP and will provide an additional disinfection barrier, particularly with regard to virus and bacteria. The chlorine disinfection system will utilise the existing ETP chlorine plant and be capable of operating in both free chlorine and combined chlorine (chloramine) disinfection modes. Chlorination will be controlled to meet disinfection requirements and residual targets.

5.6.2 Chlorine disinfection system design basis

Chlorine dosing

The following chlorine dosing points will be provided:

• At the inlet to the TWS, which will be the primary chlorine dosing point for the ATTP.

• The existing dosing point at the suction of the OPS pumps will be retained as a back-up chlorine dosing point. In the unlikely event of the ATTP having to be bypassed, this dosing point will therefore remain available to chlorinate secondary effluent before it is discharged from site as per current practice.

The chlorine dose to the main process flow will be controlled by a flow-paced control algorithm that is trimmed based on on-line chlorine residual measurement. The flow input will be from a flow meter located immediately downstream of the chlorine injection point. The chlorine residual will be monitored by on-line analysers. Chlorine will be supplied from the existing gaseous chlorine facilities on the ETP site. No additional storage is proposed. Chlorine transfer to each of the dosing points will be as a supersaturated aqueous chlorine solution as per the current system. Chlorine will not be transferred to any dosing point as liquid or gaseous chlorine. Some chlorination equipment augmentation may be required to account for the longer transfer distance to the proposed dosing point at the inlet to the TWS as compared to current dosing point at the OPS. Upstream ozone-BMF treatment has the capability to produce treated water with very low ammonia levels through its ability to nitrify residual ammonia in the secondary effluent. Therefore, chlorination will generally be in the form of free chlorine for a majority of the time. There is potential for ammonia concentration to increase as a result of certain


events such as higher plant flows associated with peak wet weather events. Under such circumstances low levels of ammonia will be breakpoint chlorinated as determined by the chlorination system capacity, or alternatively the chlorination mode will be switched from free chlorination to combined chlorination (chloramination) as per current practice at ETP. The design of the ATTP will address both chlorine disinfection modes. Chlorine will be contacted with the main process flow in the TWS which will be designed and operated to provide the required chlorine contact time for final disinfection. When operating in combined chlorine mode, the TWS will operated at close to its maximum operating level in order to maximise contact time. The actual retention time will be continuously controlled and monitored using a combination of ATTP and OPS flow, TWS outlet gates, and TWS level transmitters thereby enabling the Ct value to be calculated for process monitoring, compliance and reporting purposes. The design operating conditions for the chlorine disinfection system is presented in Table 5.15 below.

Table 5.15 Chlorine disinfection system design basis

Design Parameter Units Chlorine Disinfection Mode Free Chlorine

(typical operation) Combined Chlorine

(chloramine)

Ct mg.min/L 40(1) 345 Design chlorine residual mg/L 1 5 Required contact time mins 40 69 Design min baffling factor - 0.6 Minimum gross contact tank volume (max. 758 ML/d future flow)

m3 35,100 60,500

Median chlorine use kg/d 1,580 N/A Peak chlorine use (max. output of duty chlorinators)

kg/d 7,200 N/A

Notes: (1) The design basis for free chlorine is a Ct of 10 to 40 mg.min/L representing the lower and upper bounds subject to confirmation through further investigations.

Chlorine handling and leakage monitoring will be in accordance with Dangerous Goods Regulations, and chlorine solution will be run in double contained pipes which will drain to safe collection points.


Dechlorination

When the chlorine disinfection system is operating in combined chlorine (chloramination) mode the chlorine residual at the outlet of the TWS will be up to 5 mg/L chlorine. Chloramines are a persistent form of chlorine and such a residual without adjustment would be expected to result in elevated residual chlorine at the Truemans Road sampling point. Therefore a dechlorination system will be provided to control and limit the final treated water chlorine concentration. The basis of the design is to lower the total chlorine concentration to approximately the current operating levels of 1.0 mg/L at the OPS. Dechlorination is expected to be rarely required. The dechlorination process involves dosing a reducing agent that reacts readily with chlorine and lowers the chlorine concentration in the treated water. Reducing agents are typically used to achieve dechlorination with sodium bisulphite, sodium metabisulphite, and sulphur dioxide being the most common chemicals used. Sodium bisulphite has been selected as it is readily available in liquid form thereby eliminating many OH&S issues compared to solid sodium metabisulphite. Sodium bisulphite will be dosed into the treated water storage basin discharge chamber based on flow and residual chlorine levels if needed. The design dosing regime is described in Table 5.16 below.

Table 5.16 Sodium bisulphite design basis

Design Parameter Units Value Design excess chlorine to be removed mg/L 5 Design dose ratio SO2:Cl 0.9:1 SO2 concentration - 20% Design sodium bisulphite solution dose mg/L 22.5

Sodium bisulphite will be stored in bunded tanks immediately adjacent to the dosing point. Filling of the chemical tanks would be via tanker from a bunded loading station and tanker standing area.

5.7 Treated water storage

The preferred location for the TWS is south of the ATTP and between the SEHB and the Chelsea-Frankston Sewer as set out in the conceptual view and outline layout drawings in Appendix B. This location simplifies construction, provides footprint flexibility,


maximises free storage in the existing EHBs, and locates the TWS away from the secondary effluent in the EHBs. A minimum combined TWS volume of 64 ML is proposed. The TWS will comprise two identical basins of 32 ML each. The basins will be internally baffled to achieve the design minimum baffling factor of 0.6 (e.g. actual minimum retention time will be 0.6 of total volume theoretical retention time). Proposed basin construction uses earthen construction with a 2:1 (horizontal: vertical) sloping wall with sand and crushed rock under a geotextile and polypropylene liner. The basins include concrete inlet and outlet structures, an access ramp, and an emergency high level overflow routed to the EHBs. The TWS is located above ground water level, and minimum operating level in the TWS is above local ground level. This prevents potential contamination via infiltration from groundwater. The basin includes a cover system complete with drainage arrangements to convey rainwater off the surface of the basins, again protecting the ATTP final treated water from contamination. The TWS includes an inlet structure with penstocks to isolate flow to either storage basin for maintenance. The inlet structure includes chlorine residual monitoring to provide feedback to control the chlorination dosing upstream of the storage basins. Chlorinated treated water is combined at the outlet structure and directed to the OPS for conveyance offsite. The outlet structure will also includes gates for basin isolation for maintenance. The provision of control gates for basin level/flow control in relation to chlorine disinfection control will be reviewed.

5.8 Residuals management

5.8.1 Description

The BMF process will capture and remove residual suspended solids from the secondary effluent and therefore produce an additional residual solids stream. The nature and quantities of this residual solids stream are discussed in further detail in Section 7.9.2. This new residual solids stream will essentially be the same as the plant’s existing secondary waste activated sludge (WAS) stream and will be treated accordingly, including thickening, stabilisation in the existing anaerobic digesters to produce biogas and discharge to the existing sludge drying pans.


5.8.2 Backwash balancing tank

Spent backwash from the BMF process will flow by gravity to the backwash balancing tank. The tank is required to balance the intermittent flows from the BMF backwash and allow a steady feed to the downstream solids separation and thickening process. The size of the backwash balancing tank is based on the peak flow received from the BMF system. Each filter requires backwashing once a day on average and a maximum of twice per day, with up to 2 filters being washed at one time. Additional storage capacity in the balancing tank is also provided to allow for short term mechanical failures in the residual solids handling system. The backwash balancing tank is split into two concrete tanks, each with a working volume of 1,000 m3, and will be located partially below ground level. The tanks will have a common inlet structure which receives the gravity flow via a pipeline from the BMF. This inlet includes an overflow weir to the Chelsea-Frankston Sewer, which leads to the head of the ETP process, to allow the residual solids separation and thickening process to be bypassed in the event of major mechanical failure. Under normal operation the homogeneity of the spent backwash water will be maintained by low energy submersible mixers located in the tanks. The mixers will retain solids in suspension while allowing small amounts of carried over filter media to settle. The filters can be expected to lose up to about 2% of their media per annum. This equates to about 100 m3 per annum of media that will need to be removed from the spent backwash prior to the solids separation and thickening process. The two tanks allow one tank to be taken offline for maintenance, including the removal of trapped media using a suction tanker from a sump in each tank. Other options for removal of trapped media will be considered during the detailed design. Spent backwash water will be transferred from the backwash balancing tank to the downstream solids separation and thickening process via a pump well fitted with submersible pumps.

5.8.3 Residual solids separation and thickening – tertiary DAFT system

The BMF backwash stream will have a low solids concentration and therefore the residual solids will be separated from the liquid stream and thickened to a target concentration of up to 3% dry solids so as to be suitable for addition to the existing anaerobic digesters. At this stage of design it is proposed to provide a dissolved air flotation thickening (DAFT) system for this purpose which is directly comparable to the DAF process


successfully employed at ETP for thickening the current WAS stream. Alternative treatment processes, including sedimentation, are also being reviewed and assessed as part of ongoing design development activities to determine the preferred approach based on whole of life cost and environmental considerations. The DAFT process involves dissolving air in water under pressure and then releasing the air at atmospheric pressure in a flotation tank or basin. The released air forms tiny bubbles which adhere to the suspended matter causing the suspended matter to float to the surface of the water where it may then be removed by a skimming device.

The flow of unthickened spent backwash water from the backwash balancing tank will be split evenly to four parallel DAFT Tanks by a flow split chamber with weirs. A polymer and coagulant dosing system will be provided to assist in achieving the target thickened solids content. The clarified effluent subnatant stream from the DAFT will be discharged to the EHBs for re-treatment by the ATTP. Each of the four DAFT tanks will be equipped with a dedicated saturation vessel to generate the dissolved air for flotation. The saturation vessels will be provided with compressed air from a central system, and with water from a common recycle system provided by the clarified subnatant. Combined saturation vessels have not been adopted as they reduce control and redundancy. The thickened solids float will flow to a holding tank that will have about thirty minutes of storage capacity (20 m3). The thickened solids will then be pumped with duty/standby positive displacement pumps to the existing sludge digesters via a heating system as per the other existing sludge streams sent to digestion. The design basis for the DAFT system is provided in the Table 5.17 below.


http://en.wikipedia.org/wiki/Atmospheric_pressure

Table 5.17 Tertiary DAFT system design basis

Equipment Units Size Peak/Average design flow to DAFT ML/d 52/21 Peak solids loading (N) (kg/m2/d) 80 Peak hydraulic loading (4 duty) (m3/m2/hr) 7.2 No. of DAFT tanks (incl. flocculation tanks) No. 4 Size of DAFT tanks (incl. flocculation tanks) (each) m2 75 No of flocculation tanks No. 8 Flocculation tank retention time (each) min 10 Peak/Average recycle rate ML/d 7.9/3.2 Coagulant type - ACH Thickened solids float concentration % dry solids Up to 3 Solids removal efficiency % 90 Air compressor system No. 2 (1-duty, 1-standby)

5.8.4 Residuals stabilisation

Thickened solids from the DAFT tanks will flow to a holding tank prior to being pumped to the existing anaerobic digesters. This new solids stream from the ATTP will account for about 3% of the total sludge feed to the digesters and will be blended with the sludge from the main plant before being introduced to the digesters. The capacity of the existing digesters to deal with the extra solids load has been investigated and found to be acceptable. The DAFT solids management system will include a sludge storage hopper, macerator and transfer system, a means for heating the sludge via heat exchangers and connection to the digester feed system. The residual solids heat exchangers have been based on existing equipment at the ETP. A total of two heat exchangers are required for the additional sludge being sent to the digesters. Hot water for heating the tertiary residual solids may be drawn from the existing plant hot water heat recovery system, which uses waste heat from onsite power generation. The proposed location of the heat exchangers is in one of the spare rooms within the tunnel system adjacent to the digester piping gallery.


The thickened and heated tertiary residual solids stream will be introduced into the feed lines to the digesters at a point to ensure adequate mixing with other streams being fed to the digesters, such as thickened primary sludge and thickened WAS.

5.9 Alkalinity correction system

The ETP secondary effluent is relatively low in alkalinity and the additional alkalinity consumption from nitrification by the BMF treatment step could at times lower the alkalinity even further resulting in low treated water pH. In order to ensure appropriate control measures are in place to maintain the pH it is proposed to provide a hydrated lime dosing at the ATTP. A range of supplements have been considered to provide alkalinity and pH correction. At this stage it is proposed to use hydrated lime as the design basis, although final selection will be reviewed and confirmed as part of detailed design activities. Hydrated lime will be dosed at the head of the ATTP immediately downstream of the TSPS. Lime dosing is expected to be intermittent and will be dependent on the following considerations:

• Secondary effluent alkalinity is dependent on the degree of nitrification/denitrification in the activated sludge process. Maximising denitrification here will minimise the need for lime dosing. This is currently not a treatment requirement for ETP

• The full denitification capacity of the activated sludge process will be fully characterised once the four new aeration tanks are commissioned at the end of 2009 (i.e. this year).

• The planned introduction of desalinated drinking water into Melbourne’s drinking water supply will result in an increase in ETP alkalinity levels due to the desalinated water having a higher alkalinity than current surface water drinking sources. The actual impact on ETP will be dependent on the proportional contribution of desalinated drinking water to the ETP catchment and this will be variable.

The hydrated lime plant will comprise storage silos, slurry metering, batching tanks and dosing pumps based on similar installations used for drinking water pH correction. Two silos will be provided with a maximum height of 20m above ground level. Appropriate dust control filters will be provided on the silos and associated slurry tanks. The proposed installed capacity will be in the range of 3,000 to 8,000 kg/day. Based on the lower bound of the projected increase in ETP alkalinity associated with the introduction


of desalinated drinking water, the estimated annual lime consumption is around 200 tonnes/yr. The design basis for the hydrated lime plant is provided in the Table 5.18.

Table 5.18 Hydrated lime system design basis Item Units Size

Total silo capacity (t) tonnes 80

No. of silos No. 2

Silo dimensions (each) - 3m dia x 15m tall

No. of slurry tanks No. 2

Slurry tank capacity (each) m3 7.5

Overall plant footprint (LxWxH) m 15 x 15 x 20 The hydrated lime will be wetted to form slurry of between 2.5% and 5% solids for ease of use. The addition of hydrated lime (Ca2+)will result in a decrease in the sodium adsorption ratio (SAR) through the relationship SAR = [Na+] / (([Ca2+] + [Mg2+])/2)0.5. The SAR of the current ETP effluent is already suitable for irrigation and any periods of lime dosing for pH correction would of course further improve the SAR.

5.10 Electrical system

The electrical system will designed as a stand alone 22 kV electrical network with power being made available from augmentation of the existing Eastern Treatment Plant 22 kV supply network. The ATTP will be supplied with two independent metered 100% capacity feeders. The ATTP electrical system will be configured with a two bus main 22 kV switchboard with bus tie circuit breaker and radial transformer feeders to the various process areas around the plant. Each process area will be supplied by two 100% capacity feeders and 22 kV / 415 V step down oil filled hermetically sealed transformers. The 415 V unit switchboard will be configured with two buses and a bus tie circuit breaker. The unit switchboard will directly


supply all large drives and packaged motor load centres, light and power for the area and instrumentation and control power. Essential power for the ATTP will be sourced from the existing site 415 V emergency power system. The electrical system will be monitored in the ATTP control system indicating circuit breaker status, fault status and power demand in each feeder. Consideration will be given to remote control of the electrical system circuit breakers from the ATTP control system to allow the operator to re-instate the ATTP to full operation on loss of power supply to one feeder. The electrical system will include protection schemes as follows:

• Feeder differential (pilot wire) on the incomer 22 kV feeders • Bus zone protection on the 22 kV switchboard • Overcurrent and earth fault protection on the transformer and capacitor bank

feeders • Overcurrent and earth fault on the 415 V unit switchboards • Trip circuit supervision and circuit breaker fail protection on all circuit breakers.

The protection relays will communicate with the ATTP control system to provide information of trip status, warning status, time to trip, time to reset, phase current, phase voltage and power demand.

5.11 Instrumentation, control and automation

5.11.1 General

The ATTP control system will automatically perform the day to day control of the plant and will monitor and report on process performance. Under normal operations, operators will monitor the ATTP from the existing ETP control room (Eastern Control Centre or ECC) which is manned continuously (24 hrs/365 days). The ATTP will have operator workstations in an operations room attached to one of the switchrooms at the ATTP, and the same functionality will also be available to the ECC.


5.11.2 Integration considerations

The ATTP control system will integrate with the existing Siemens PCS7 control system at the ETP. The degree, and possible staging (if any), of this integration will be fully defined by an integration strategy which will be developed during detailed design. It is expected that the degree of integration will ultimately be quite extensive and seamless from an operator’s perspective. Though specific vendors have not yet been selected, it is certain that some of the process equipment packages being considered will be supplied complete with internal control systems. These process equipment packages will be integrated with the ATTP plant control system in accordance with the integration strategy described above.

5.11.3 ATTP control system architecture

The architecture of the ATTP control system will be similar to the existing ETP plant control system. The ATTP control system architecture will include the following key features:

• A control local access network (LAN) network having a self-healing, optical fibre ring topology

• A plant control system (PCS) data LAN network having a self-healing, optical fibre ring topology

• Human machine interface (HMI) servers (redundant) separate from existing ETP HMI servers

• Shares the existing historian server • Two HMI workstations located in the ATTP operation room plus access to ATTP

graphics pages from existing ETP HMI’s • Both a dedicated engineering workstation for commissioning and a permanent

engineering workstation • Programmable logic controller (PLC) processors distributed to process areas,

with typically one PLC processor per unit process area • An operator interface terminal (OIT) located at each PLC (each major process

area) providing limited local control facilities independent of the PCS7 HMI system

• Racks of PLC I/O (input/output) modules connected by a dedicated remote I/O network, and distributed into field mounted marshalling cabinets (referred to by MWC as distributed marshalling kiosk’s or DMK’s) located wherever clusters of field devices exist


5.11.4 Control philosophy

A control philosophy will be developed to address the functional standards of the control system, and define such things as:

• Automatic, remote, OIT and local control of field equipment and the extent of such modes of control

• Alarm generation and annunciation/transmission, alarm categories, filtering and masking and alarm acknowledgment

• Device level control of valves and motors including definition of the depth of diagnostic information being monitored by the control system

• Levels of user access control/restrictions The control philosophy for the ATTP shall be generally consistent with that of the wider ETP.

5.11.5 Interfaces with existing systems

Apart from controlling the ATTP, the control system must also interface to a number of existing systems and these interfaces shall be defined in greater detail during detailed design.

5.12 Flexibility for future process enhancements – Membrane filtration

The primary project objectives of addressing the impact of environmental discharge to the marine environment at Boags Rocks and producing a high quality fit-for-purpose recycled water resource will be met by the proposed ATTP concept design as presented in this report. The design also provides for future augmentation with ultrafiltration membrane filtration downstream of ozone-BMF treatment should it be required as part of the specific needs of future large-scale recycling projects (e.g. those requiring reverse osmosis treatment). The ability to augment the ATTP with membrane filtration has been considered as part of the plant’s design as discussed below. Membrane filtration has been investigated as part of the Tertiary Technology Trials both upstream and downstream of ozone-BMF treatment. While both applications were found to be technically feasible, membrane filtration was found to be much more efficient


downstream of ozone-BMF treatment, as compared to direct secondary effluent feed, due to the improved water quality. Hence the preferred location of a future membrane filtration plant is downstream of ozone-BMF treatment. Augmentation of the ATTP would essentially comprise insertion of a membrane filtration system between the BMF system and downstream disinfection systems. Given that UF membrane filtration would provide equivalent or greater removal of protozoa and bacteria than the UV disinfection system is designed for, it would not be necessary to send the membrane filtered water through UV treatment and therefore it is expected that it would be discharged directly to the chlorine disinfection system and TWS. An outline layout drawing for the augmented ATTP with future membrane filtration is provided in Appendix B. Addition of a membrane filtration step would include the following new plant elements depending on use of either a pressure-based or immersed membrane configuration:

• Membrane feed water pump station (pressure-based configuration) • Membrane filtration plant, comprising the membrane filtration modules

(pressure-based configuration) or tanks (immersed configuration) • Membrane permeate pump system (immersed configuration) • Membrane permeate storage tank for backwashing and cleaning solutions • Membrane backwash pump and air scour blower systems • Membrane cleaning systems, including chemical unloading, storage and dosing

systems (such as sodium hypochlorite, sulphuric or citric acid, and caustic) • Spent membrane backwash water handling system, including a balancing tank

and DAF thickening process consistent with that proposed for the ATTP.


6 Operational reliability and redundancy

6.1 Introduction

The ATTP design incorporates a range of measures to provide the requisite level of operational reliability and redundancy in a cost effective manner as driven by the following general requirements:

• The ATTP must not inhibit the ability to discharge treated effluent off-site via the OPS.

• The primary objective of the ETP Tertiary Upgrade Project is to address impacts of the existing treated effluent discharged on the receiving environment at Boags Rocks. The ATTP must therefore be capable of treating all ETP flows.

• The secondary project objective is to produce high quality fit-for-purpose recycled water. The required availability of recycled water production ultimately depends on the recycled water end uses and associated recycled water scheme management plans. The availability of recycled water production may be less than the requirement to treat all ETP flows.

In addition, the following general operational reliability and redundancy requirements are relevant:

• For each group of operational units, one standby unit, with a minimum of 25% standby units, will be provided.

• There will be no single common point of failure. There is also provision to consider non-installed standby equipment, such as spare pumps which may be stored on-site for quick replacement in lieu of complete installed redundant equipment. The capability of the key elements of the plant design to address these requirements is addressed below.


6.2 General ATTP design considerations

There are three key aspects of the ATTP concept that inherently contribute to operational reliability of the proposed effluent design:

• The ability to store secondary effluent in the EHB system: The existing 2,000 ML EHB system provides buffering storage between the secondary treatment process and the OPS in the event of high flow wet weather events. Under such conditions the system stores the secondary effluent flows (max. 1,750 ML/d) in excess of the OPS capacity (max. 708 ML/d). During normal dry weather operation only a small portion of the EHB system is used to balance the diurnal secondary effluent flow and fixed speed OPS pump set operation on a daily basis. MWC is proposing to augment the EHB system by undertaking the Western Effluent Holding Basin Project to address peak flow events, and which would provide an additional 1,000 ML of storage thereby providing a total system capacity of 3,000 ML.

• The ability to operate the ATTP at variable capacity: The ATTP design basis provides for fully variable flow capacity between 130 and 708 ML/d treated water production. Therefore, when considered in conjunction with the EHB system, it will be possible to optimise ATTP throughput in the event of any degree of plant unavailability.

• Adoption of a robust feed water design basis: The capacity of the ATTP is determined by a combination of flow and secondary effluent quality. Given that the ATTP must pass all flows at ETP, it has generally been designed based on peak flows and loadings as supported by long-term historical data records for the site. However, considering that peak flow events are wet weather event related and generally limited to <3 weeks a year, the ATTP will be operating substantially below its peak design loadings during normal weather conditions thereby providing a degree of inherent plant redundancy.

• Provision of overflows and returns to the head of treatment: A number of emergency overflow systems have been incorporated into the plant design whereby flows can be safely returned to upstream processes for re-treatment in a controlled manner. These provisions enable the plant to continue operating at optimised throughput in the event of any short-term capacity constraints.


6.3 Tertiary supply pump station

The pump station will comprise 5–duty and 2-standby pumps providing 40% redundancy compared to 25% minimum redundancy requirement.

6.4 Ozone system

The ozone contactor system will comprise two parallel pipelines. While hydraulic plant elements are not subject to redundancy requirements due to their inherent high reliability and availability, considering that the ozone contactor has a critical treatment function the provision of dual process contactors provides operational flexibility in terms of being able to continue treating the average annual plant flow with one contactor out of service for maintenance, and also eliminates a potential single point of process failure. The reliability and availability of oxygen feed gas supply and ozone production is addressed by the following:

• The LOx system is sized to meet the oxygen supply requirements in the event of the VPSA plant being unavailable. The vapourisers and gas flow controls are sized for the full oxygen demand.

• The ozone plant is designed with 4-duty and 1-standby ozone generator thereby meeting the minimum of 25% redundant capacity. In the event that one generator is unavailable, the ozone demand can still be met with 3-duty and 1-standby generator by temporarily operating at a lower ozone gas concentration. While this mode results in higher oxygen feed gas consumption and therefore reduced efficiency, it provides a means of maintaining both oxygen supply and redundancy in the event of an unplanned generator outage.

• The ozone injection system comprises 6-duty and 1-standby side-stream injection system. Each ozone contactor will have three dedicated injection systems with the standby unit configured so as to be able to be used for either contactor. This configuration provides 33% redundancy for any one of the two contactors, as required to treat the average annual flow. The redundancy is reduced to 17% across both contactors at peak wet weather flow. Additional redundancy can be provided using a feed from the service water system and maintaining spare pumps onsite.

• The ozone off-gas destruction system comprises 4-duty and 1-standby ozone destruction unit on the basis of one destruction unit for each ozone generator thereby satisfying the 25% minimum redundancy requirement.


6.5 Biological media filtration system

Under peak solids loading conditions (high flow and high TSS concentration), a peak design filtration rate of up to 12 m/h will be maintained with 3 of the 36 filters being unavailable (either 2 filters backwashing simultaneously and 1 out of service, or 1 filter backwashing and 2 filters out of service). Therefore the impact of a single filter failing for any reason would be minimal, with no change in filtered water quality.

In addition, should another 2 filters be unavailable, leaving 5 of the 36 filters being unavailable, the peak filtration rate would only increase from 12 to 12.8 m/h. This is also expected to have minimal impact on filtered water quality.

The BMF backwash pump system comprises 4-duty and 1-standby pump and the BMF air scour system comprises 4-duty and 1-standby blower and therefore both systems meet the 25% minimum redundancy requirement.

6.6 Residuals handling system

The spent BMF backwash balancing tank comprises two compartments such that operation can be maintained during annual average conditions while one of the tanks is out of service for maintenance or cleaning. There is no specific redundancy in the tertiary residuals handling system at peak loading conditions but the provision to enable discharge of any excess unthickened backwash water to the head of ETP via the sewer ensures system operation remains unconstrained. During normal operation spent BMF backwash water will be treated by a DAFT to separate residual solids from the wastewater stream, and the thickened residual stream will be sent to the digesters while the clarified effluent stream will be sent to the Forebay inlet. In the event that the tertiary residuals handling system is unavailable, it will normally be possible to discharge unthickened spent backwash water directly to the Chelsea-Frankston Sewer for return to the head of ETP to enable continued operation of the ATTP. Under average annual conditions the unthickened spent backwash stream will be around 21 ML/d and, given this represents only a minor impact on ETP treatment systems, discharge to sewer could be undertaken for up to several weeks in the event of tertiary residuals handling system unavailability. Under peak flow and load conditions, the unthickened backwash water increases to around 52 ML/d. Discharge to sewer under these conditions could be undertaken for up to several days depending on the loading and conditions of the ETP treatment systems. These measures ensure a very high reliability of the residuals handling system as a whole.


6.7 UV disinfection system

The design of the UV disinfection system will ultimately be dependent on the selection of the preferred UV technology supplier and a nominal design has been adopted for the purpose of Concept Design. This discussion of operational reliability and availability is therefore applicable to the nominal design comprising 5 channels with each channel having 3 banks of UV lamp modules. The UV disinfection system has been designed based on the combination of a peak flow condition of 708 ML/d and 5th percentile UVT of 55%. This represents an extreme loading scenario and ensures system operational reliability and availability is provided through a combination of the following considerations:

• The 5th percentile UVT is associated with dry weather flow conditions and the UVT is in fact higher during peak flow conditions due to wet weather flow dilution. The calculated UVT at peak (wet weather) flow could reach 64%. Considering that the UV system capacity (power) to achieve a nominal UV dose is (non-linearly) inversely proportional to UVT, the full capacity of the system will not be required at peak wet weather flow.

• Under normal conditions the 5th percentile UVT of 55% should only occur under dry weather flows up to 570 ML/d (two OPS pump operation) as compared to the design peak flow of 708 ML/d. At this flow and UVT one of the five channels could be out of service without affecting treatment.

• In practice, ozone dosing can be controlled to constrain the minimum UVT further by modulating the ozone dose in response to varying secondary effluent quality.

• At average annual flow conditions of 380 ML/d and 5th percentile UVT the system redundancy would be higher again meaning that two of the five UV channels could be out of service.

• In the event of unavailability of parts of the UV disinfection system, flow through the system can be modulated and optimised to maintain maximum throughput taking into account the actual UVT at that time, and the target UV dose required.

• Spare critical equipment components, such as electrical, instrumentation and control components, can be maintained on-site to mitigate the impact of unplanned outages.

• The system will be designed based on performance at end of lamp life when minimum lamp output occurs. As a result system capacity will always be greater than the minimum design basis.


The operational reliability and redundancy of the UV disinfection system will ultimately be specified on the basis of the preferred UV technology supplier as determined through subsequent project delivery activities.

6.8 Chlorine disinfection system

It is proposed to augment the existing ETP chlorine dosing system to provide chlorine to the ATTP. Existing primary chlorination plant comprises three 150 kg/h chlorinators dedicated to post-chlorination (i.e. at the OPS). Two chlorinators are required to provide the peak proposed chlorine supply rate to the ATTP and therefore it is currently proposed that the existing chlorinators will operate as 2-duty and 1-standby thereby providing 50% redundancy.

6.9 Treated water storage

The TWS comprises two separate basins such that average annual flow can continue to be treated while one basin is out of service for maintenance.


7 Environmental and social considerations

7.1 Introduction

Through significantly improving the final effluent quality discharged from ETP, addressing environmental impacts at Boags Rocks and producing a high quality recycled water resource, the Tertiary Upgrade Project inherently benefits both the environment and the community. The following sections focus on the environmental and social considerations associated specifically with the implementation of the ATTP at the ETP site. The proposed location of the ATTP is a brownfield site within existing wastewater treatment infrastructure. The site has been significantly altered from its natural state and therefore environmental impacts associated with implementation of the proposed ATTP are limited. 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. All construction activities will be undertaken in accordance with the Environmental Protection Act 1970 and regulations. EPA Victoria Publication 480 – Environmental Guidelines for Major Construction Sites will be used as a framework for creating sound working practices that minimise the environmental impacts of construction.

7.2 Air

The only notable impact on air quality associated with construction of the ATTP is the potential of dust resulting from construction activities. However, these construction activities will be directly comparable to those routinely undertaken at the ETP site, including earthworks activities associated with sludge drying pan refurbishment, or major projects such as the new odour control facilities or current aeration tank construction. The potential for dust to impact on air quality will be addressed through employing standard dust suppression measures and is expected to have minimal impact on the surrounding environment. Standard approaches to dust management include minimising


areas of open excavation, grass seeding spoil heaps, restricting speeds on haul roads, and using water trucks to wet down haul roads and excavated areas. The ATTP is not expected to alter the overall odour performance at the ETP site primarily due to:

• Treating secondary effluent which has low odour emission rates - there are already large exposed surface areas of secondary effluent which do not contribute significantly to the overall odour performance of the site

• Ozone-BMF treatment further reduces effluent odour • The backwash thickening process is similar to existing dissolved air flotation

tanks onsite and it will receive residual solids from an ozonated aerobic source of low odour potential

7.3 Noise

Given that the ATTP will be located in the centre of the ETP site and that extensive construction activities at site are undertaken without problems, the impact of construction noise on local residents is expected to be minimal. The nearest residential properties are more than 1.2 km from the construction site. The majority of construction noise should occur during normal working hours. Where after-hours construction is unavoidable and could potentially be audible from local residences, a community consultation program will be implemented. Noise from the operational ATTP is not expected to have any impact at the ETP site boundary through the adoption of appropriate noise management measures in plant design. These are typically driven by OH&S requirements for site operations.

7.4 Surface water and ground water

Surface water run off from the construction site will be controlled with interceptor drains and bunds to prevent it entering the local water courses. Captured runoff will be passed through silt traps before being discharged to existing drainage systems. Temporary sanitation facilities will be provided for the construction site and plumbed into the local sewer to the head of the works. The water table is typically at 0 to 1m AHD which is between 2m and 6m below the surface at the ETP site and therefore construction activities are not expected to encounter


significant quantities of ground water in excavations due to the shallow depth of the excavations and the low level of the water table at the works area. While no significant dewatering of excavations are anticipated in the ATTP construction is expected, where ground water is encountered it will be extracted from the excavation using sump pumps and managed in the same manner as run off above. The groundwater is classified as Segment B (suitable for irrigation and potable mineral water) and is brackish (TDS: 1,200-1,400 mg/L). No significant effect on groundwater discharge to the Patterson River or Carrum-Edithvale swamp is expected.

7.5 Land

The land occupied by the ETP is zoned Public Use Zone 1 (Service and Utility). The construction of the ATTP will require significant numbers of vehicle movements during earthwork and concreting activities. The construction site will be accessed from Thompson Road using the existing site access. Thompsons Road is a major through road and links to the Mornington Peninsula freeway and the East Link freeway roads without passing through residential areas. However, as part of the construction program the number of vehicle movements outside normal working hours will be minimised where possible. To assist in managing construction traffic turning on Thompsons Road appropriate signage will be deployed. Where necessary wheel washing facilities will be provided at the construction site entrance/exit to ensure that mud is not carried on wheels and vehicle under-bodies onto public roads. As required diesel fuel will either be brought on to the site daily in specially modified fuel trucks to fill plant or it may be stored on the construction site in a temporary fuel store facility. Any fuel store will comply with all regulations applicable to the use and storage of diesel oils, petrol, paraffin and other inflammable fuels and will ensure that adequate precautions are taken against fire. The fuel will be stored in a well ventilated area, away from ignition sources in purpose made metal storage containers. All fuel stores will be contained in purpose built bunds and secured in a lockable fenced area.


7.6 Flora and Fauna

7.6.1 Flora

Construction works at ETP for the ATTP would occur on a site largely occupied by a carpark, a 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. The proposed location for the ATTP consists of exotic pastures and paddocks of non-native pasture grazed by cattle surrounding the treatment facilities, with some screening plantings of native trees. The majority of the proposed construction area is dominated by degraded treeless vegetation and a disused site hard stand compound. MWC recognises the importance of the ETP site from a biodiversity context and will endeavour to maintain as much of the existing vegetation as possible. The layout of the ATTP has been undertaken in consideration of the vegetation management hierarchy of options: avoid, minimise and mitigate any impacts. Complete avoidance was found not to be practicable. It is possible to minimise impacts through design and management, with new plantings to provide habitat and offsets for the portion of current plantings which would have to be removed in the area in question. Construction of the ATTP will necessitate removal of a number of trees. The only indigenous remnant vegetation observed within the study area is in poor condition and consists of one mature swamp paperbark (Melaleuca ericifolia) and one tea-tree (Leptospermum sp.) with no indigenous understorey. A number of native trees, planted as a possible screening or windbreak around 30 years ago, will require removal. MWC is committed to undertaking offset plantings to address the necessary removal of native vegetation in a manner consistent with requirements of the Planning and Environment Act 1987 and the Victorian Government’s Native Vegetation Management – A Framework for Action 2002 which form the guiding principles under which native vegetation is managed in Victoria.

7.6.2 Birds

Migratory and wading birds are recorded in and around the ETP and are significant species that must be protected. Some species are also listed by the Japan-Australia and


China-Australia Migratory Bird Agreements (JAMBA and CAMBA respectively). Migratory species are vulnerable to disturbance to their feeding and resting behavior that can prevent them gaining sufficient fat reserves to successfully complete their return migration. Wading birds can experience disturbance to their breeding, nesting and feeding routines from factors such as movement and noise and fail to breed successfully. The proposed ATTP construction will have minimal interfaces with the EHBs, where the majority of the migratory and wading bird species are located, and hence direct interference with the birds should be minimised. Works related to hydraulic structures around the Forebay and OPS will require the draining of the Forebay for several months. This is a routine maintenance activity at the site (generally undertaken every five years) to remove settled solids from the basin floor. When the Forebay is drained, an additional EHB will be brought into service to conserve hydraulic buffering volume and thereby maintain the same water surface area. During plant operation, the new TSPS interface with the EHBs will simply substitute for the current OPS interface with the EHBs and therefore there will be no net change in this respect. MWC works closely with Birds Australia to maintain and improve bird habitat at the site, and Birds Australia undertake monthly bird surveys and have a representative on the ETP Community Liaison Committee. Measures undertaken by MWC to provide bird habitat include:

• Maintaining water in the ‘Golden Triangle’ area using recycled water. This is a collection of decommissioned sludge drying pans located to the north west of EHB system.

• Construction and planting of the ‘Doughnut’ pond and keeping it topped up with recycled water. This area has also been furnished with nesting boxes.

• The western-most EHB 6 has been planted with wetland plants and a residual amount of water is usually maintained in this basin.

• The SEHB usually has a residual water level to provide habitat. In addition, MWC has wetlands at Edithvale and have just constructed a wetland in the south east corner of the ETP site on Boggy Creek. Most of the above bird habitat areas are removed from the proposed location of the ATTP and therefore any impacts of plant construction on birds is expected to be minimal. A review of all mitigation measures currently in place at the ETP will be undertaken to protect the threatened fauna species that occur at the ETP site and incorporate any project


specific additional measures to protect species during the construction and operation phases of the plant as required.

7.6.3 Bats

While bats have not historically been listed in Melbourne Water’s Biological Database of the ETP site, a recent preliminary bat survey commissioned by MWC identified a number of microbat species within a study area comprising ETP, Edithvale-Seaford Wetlands, Wannarkladdin Wetlands, Boundary Road Wetland and PARCS Wetland. Of the seven species of microbats and three species complexes (similar morphology) identified within the study area, five species and two species complexes were identified within the ETP site. The study also potentially identified the state significant and the Flora and Fauna Guarantee Act 1988 (FFG) listed Eastern Bent-wing bat within the study area. While the Eastern Bent-wing bat was potentially identified at ETP at a survey location around 1 km west of the proposed ATTP location, it was not identified at a survey site around 100 m west of the proposed ATTP location. A key recommendation of the preliminary study, which is proposed to be implemented to further improve MWC’s understanding of the importance of the ETP study area, is to undertake a Level 2 assessment during October/November 2009 comprising harp trap surveys to further assess species diversity and abundance to establish if the species recorded as potentially occurring within the study area are in fact present. The ATTP is to be constructed within close proximity to one of the preliminary study survey locations at ETP. Irrespective of whether microbats use the area as roosting or foraging sites, which will be better understood through the Level 2 assessment, MWC recognises the importance of the site from a biodiversity context and will endeavour to maintain as much of the existing vegetation as possible, and compensate any necessary vegetation removal. Where existing vegetation, which may potentially provide microbat habitat, is required to be removed/pruned, then the following mitigation strategies will be implemented as proposed by the preliminary study findings:

• Felling/pruning works is to be undertaken in October or March. • Prior to pruning/felling, inspection of decorticating bark and/or hollows is to be

undertaken by a suitably qualified zoologist. The zoologist will also inspect the branch or trunk when it is lowered to the ground. The branch will be left on the ground for at least 48 hours to allow any bats that may still be present to escape. Once this period has elapsed, any roosting cavities should be opened carefully and examined for remaining bats.


• Where possible, trees and branches are to be left where they fall and pruned material is to be maintained on-site in a semi-shaded area to support woodland insects and provide foraging habitat for microbats.

• Bat boxes are to be installed prior to removal/pruning of any large trees or works on buildings where bats are known to be present.

7.6.4 Other

The drainage line in the vicinity of the proposed ATTP location, and containing some indigenous aquatic vegetation and habitats for common frog species, will be largely unaffected. Consideration of minimising any impact during construction will need to be given.

7.7 Cultural heritage

A desktop study has determined that no known Aboriginal or European heritage sites are located in the ATTP activity area at ETP. While the entirety of the activity area is considered an area of Aboriginal cultural heritage sensitivity on the basis of the local geomorphology, significant ground disturbance from prior works associated with the ETP have demonstrably eliminated the cultural heritage sensitivity in the areas so affected. Furthermore, an associated field inspection found no obvious indications of preserved historical landscape elements and the risk of an Aboriginal archaeological site of high significance occurring within the activity area is considered to be low. The Aboriginal Heritage Regulations 2007 do not specify the need for a mandatory Cultural Heritage Management Plan (CHMP) for the proposed development, as required in Section 46 of the Aboriginal Heritage Act 2006. However, a voluntary CHMP will 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.

7.8 Community engagement

Stakeholder and community involvement and engagement are important objectives for Melbourne Water in undertaking the ETP Tertiary Upgrade. The ETP Community Liaison Committee (CLC) will be the principle point of engagement to inform and to gather feedback on how to avoid and minimise any impact of construction of the ATTP. The current scheduled bi-monthly meetings with the CLC will continue throughout the construction and commissioning phases of the project and will include project updates, site inspections where appropriate, and calls for feedback from the committee.


The project delivery team (which will include MWC) for the ETP Tertiary Upgrade Project will develop and implement plans for stakeholder engagement and communications about implementation of the project. The plans will include a program of activities to inform and consult where appropriate on design and construction of the ATTP. The plans will be required to integrate with Melbourne Water’s overall communications about its responsibilities for sewerage management and the communications plan for the ETP. Engagement with respect to the design and construction of the ATTP will include the following:

• groups with an interest in the marine environment and land environment in the south east and Mornington Peninsula, including those represented on the CLC

• schools and interest groups that visit the ETP • people who visit and use the national park and beaches near the SEO discharge at

Boags Rocks • the State Government owned metropolitan retail water companies serviced by the

ETP and the SEO and which the ETP supplies with recycled water • representatives of federal, state and local government, including State

government agencies where some form of approval is required • the broader community to highlight progress with design and construction of the

ATTP. Overall, implementation and operation of the proposed ATTP is expected to have negligible negative impacts on the community on the basis that it will be located within an existing operational site.

7.9 Waste and materials use

7.9.1 Materials use

Ozone production consumes power and this is taken into account in the estimation of the plant power consumption, associated greenhouse gas emissions, and plant cost estimates taking into account MWC’s carbon offset power pricing. Thickening aids, such as coagulant and polymer, will be used in association with separating and thickening the tertiary residual solids stream. The estimated average consumption rates of coagulant and polymer are 55 tonnes/yr and 5 tonnes/yr respectively (both in terms of active ingredient).


Hydrated lime consumption, for the purpose of pH and alkalinity correction, is estimated at up to 200 tonnes/yr. The lime inert solids will be removed in conjunction with the BMF backwash and associated tertiary residual solids stream. Chlorine consumption for the purpose of final treated water disinfection is expected to be directly comparable to current chlorine consumption at the site (i.e. no net change). Some sodium bisulphate may occasionally be used for dechlorination when operating in combined chlorine mode. This is however expected to be rarely required and its annual consumption can not be readily estimated, but is expected to be very low. Plant design and materials of construction will be selected on a TBL basis taking into account life cycle cost analysis principles.

7.9.2 Residual solids

The tertiary residual solids stream will comprise:

• the majority of the residual particulate matter (suspended solids) in the secondary effluent which currently goes to the marine environment, and

• any biomass which develops on the BMF media and is sloughed off during backwashing of the filters,

• any inerts contained within the lime used for alkalinity supplementation and pH correction which are captured in the filter process, and

• solids associated with coagulation pre-treatment for the DAFT process. The thickened residual solids stream is estimated to be 2,000 tonnes/yr dry solids, or around 3% of current sludge quantities, and will be directed to the existing anaerobic digesters where it will contribute to biogas production for production of green power.

7.9.3 UV lamp cleaning

Intermittent chemical cleaning of the UV lamp sleeves is required. The volume of cleaning agent used for this process is minimal with the total cleaning solution volume washed of the cleaned sleeves into the treated water in the order of 100 L/yr. The type of cleaning gel used is specific to the UV vendors and certified suitable for use in drinking water applications (NSF61).


7.9.4 Other consumables

The principal process consumable will be UV lamps, ballasts and quartz sleeves from the UV disinfection system, and media top-up for the filters. The expected quantities are presented in Table 7.1 below.

Table 7.1 Estimated waste from UV lamp and BMF media replacement

Item Replacement Interval Total Annual Replacements UV lamps 12,000 hours 1,000 units UV ballasts 15,000 hours 750 units Quartz sleeves 2 years 1,500 units BMF media Top up as required 100- 300m3

Used UV lamps and sleeves will be returned to the UV system supplier for safe and efficient recycling and disposal. Any small amounts of BMF media that are backwashed out of the filters typically comprise fragmented media from the washing action and so would no longer be of the appropriate particle size for return to the filters. It would be combined with the ETP biosolids for reuse as appropriate.

7.9.5 Ozonation off-gas

Off-gas from the ozone system comprises approximately 99% oxygen and 1% ozone. Ozone contained in the off-gas is destructed prior to venting to atmosphere resulting in the discharge essentially comprising oxygen only. The average and maximum destructed off-gas (i.e. essentially oxygen) discharge rates are 1,650 kg/hr and 3,300 kg/hr respectively. Investigations into the beneficial use of the waste oxygen stream within the plant are ongoing.


7.10 Power consumption and carbon footprint

7.10.1 Power consumption

The estimated annual power consumption and peak connected load for the proposed ATTP design has been calculated for each process area of the ATTP based on anticipated flow and feed water quality profiles and is presented in Table 7.2 below.

Table 7.2 Estimated annual power consumption

Plant Area Average Annual Power Consumption (kWh/yr)

Tertiary supply pumps 9,120,000

Ozone 20,000,000

BMF 530,000

UV 2,630,000

Miscellaneous 3,750,000

Residuals handling 2,390,000

Chemical dosing 900,000

Total 39,320,000

The current power consumption of the OPS will not be affected significantly by the ATTP.

7.10.2 Carbon footprint

The expected upfront and ongoing emissions associated with the proposed ATTP have been calculated inline with the Federal Government’s National Greenhouse Accounts, which splits emissions into three categories.

1. Scope 1 emissions – Direct emissions generated within the boundary of the organisation’s operations.

2. Scope 2 emissions – Indirect emissions from electricity purchased and consumed by an organisation.

3. Scope 3 emissions – Indirect emissions embedded in non-electricity products used or consumed by the organisation.


Emissions are calculated by multiplying known quantities involved in the construction and operation of the plant by carbon dioxide emission factors. Where possible, the Department of Climate Change’s National Greenhouse Accounts (NGA) Factors, or emission factors from the University of Bath’s Inventory of Carbon & Energy have been used. For those emissions factors not addressed by these two sources either emission factors from other greenhouse reports, or emissions factors based on similar products have been adopted. The expected upfront and ongoing emissions associated with the proposed ATTP are presented in Table 7.3 and Figure 7.1 below.

Table 7.3 Upfront and ongoing emissions between Scopes (tonnes of CO2-e/year)

Emission Scope 1 Scope 2 Scope 3 Total Upfront 1,300 0 18,600 19,900 Ongoing 1 53,200 9,200 62,401

Scope 393%

Scope 17%

Scope 20%

Scope 1

Scope 2

Scope 3

Scope 315%

Scope 10.7%

Scope 285%

Scope 1

Scope 2

Scope 3

Figure 7.1 Estimates for Upfront (left) and Ongoing (right) emissions by scope category

Over the plant life ongoing emissions will be the major contributor to total emissions. Scope 2 (indirect electricity) emissions make up the majority of ongoing emissions. Scope 3 (indirect non-electricity) emissions form the other major contributor, and include embedded emissions in UV lamps, and sleeves, LOx, DAFT thickening aid chemicals, and lime. Chlorine usage is anticipated to be similar to existing operations and so is not included in Scope 3. The embedded energy in building materials, or Scope 3 emissions, make up the majority of upfront emissions. There are some Scope 1 emissions, generated by fuel consumption


of construction equipment and vehicles, and electricity use during the construction phase has been assumed to be negligible relative to the other emission contributors. In recognition of the critical impact of climate change on Melbourne’s waterways, water supply and sewage assets, Melbourne Water has committed to actively manage its own contribution to greenhouse gas emissions and has set targets that it will:

• reduce net greenhouse gas emissions to zero by 2018, and • increase use or export of renewable energy to 100% of total energy used, also by

2018. Melbourne Water’s key initiatives to mitigate its impact on the climate and achieve the 2018 targets include the following:

• Avoidance: Initiatives that will avoid the use of energy or the emissions of greenhouse gas in the first instance.

• Energy efficiency: Delivery of improvements in energy consumption of the systems, facilities and equipment that are already in place.

• Waste utilisation: Pursuit of opportunities to increase the use of by-products produced at Melbourne Water’s facilities or by third parties to generate energy (e.g. energy recovery from sewage treatment sludge or biogas).

• Renewable energy substitution: Identification of opportunities to substitute energy from fossil fuel with renewable energy, which does not give rise to greenhouse gas emissions. This includes on-site renewable energy projects (e.g. mini-hydro and wind generation) as well as a renewable electricity procurement strategy, which would see the balance of Melbourne Water’s electricity requirements provided by an off-site renewable electricity generator.

• Carbon Sequestration: Investigation to determine the feasibility of carbon sequestration projects on Melbourne Water managed land. These projects, including tree planting and revegetation works amongst others, might have potential to offset unavoidable emissions by removing an equivalent amount of greenhouse gas from the atmosphere.

• Purchase of offsets: The purchase of offsets supporting third party sequestration or mitigation activities.


8 Cost estimates

Project cost estimates have been developed using a bottom-up cost estimation approach based on the design information outlined in this Concept Design Report. Key aspects of the development of the cost estimates include the following:

• Adoption of local quantity surveying expertise to provide current local rates for construction labour, equipment and materials and to develop quantities and prices for civil construction and installation

• Review of estimates and construction processes by suitable experienced construction professionals

• Extensive engagement (as far as practicable) with appropriate technology and equipment vendors to obtain both costing and technical information.

• Experience from other comparable operating plants • Adoption of Risk Adjusted Nominal Estimation (RANE) methodology methods

to build in the likely cost of identified project risks. At Concept Design stage Process Flow Diagrams, preliminary Piping & Instrumentation Diagrams, basic civil and mechanical arrangement drawings, hydraulic profiles, electrical single line drawings, control system architecture drawings as well as preliminary equipment lists/sizing have been developed to support cost estimation activities. The capital cost refers to the cost of implementing the project, including all planning, design, procurement, construction and commissioning activities to deliver the fully operation ATTP. The costs that have been applied to the major cost components have been derived from a combination of the following sources:

• Factored from previous projects based on capacity or ratio • Estimated from historical data of similar project types • Preliminary take off of quantities • Current local unit rates • Project specific budget quotations.

The costs and rates used in compiling the capital cost estimate are based on current rates and prices and have been escalated to reflect the fact that the project will be implemented over a period of 36 months for completion by end 2012.


The operating cost refers to the ongoing typically annualised cost of operating the ATTP, including the following cost elements:

• Consumables including power • Routine plant maintenance and equipment replacement costs • Plant staffing and labour • Site management costs.

Certain plant components, such as instrumentation and control equipment and rotating mechanical equipment, will have to be periodically replaced at intervals ranging from 10 to 25 years. The cost for replacing this equipment is represented as an annualised capital renewal estimate. The capital and annualised operating cost estimates are presented in Table 8.1. These costs represent the RANE P50 cost, which is the most likely expected project cost accounting for known risks at Concept Design stage.

Table 8.1 Capital and Operating Cost Estimates

Cost Element Cost ($M AUD) Total Capital Cost (including escalation) 380 Annual Operating Cost 8.9 Annualised Capital Renewals 2.3



Appendix A: Historical effluent quality data at Eastern

Treatment Plant

Results Percentile NOTE 1 Sample Collection Details Method/Analysis Details Comments Parameter (generally mg/L, unless otherwise stated)

10th 50th (Median)

90th Approx. number

Data period Sample Type NOTE 8 Approx. Frequency

AWWA/APHA/WEF Std. Meth. No., unless otherwise stated

NATA

ETP Final Effluent sample point (on the Outfall Rising Main, approx. 350m downstream of the Outfall Pump Station) True Colour (Pt/Co units) NOTE 9 70 90 120 1320 Aug 02 – Jan 08 Composite Each weekday 2120 C N Total Suspended Solids 9 16 32 2660 Jan 97 - Jan 08 Composite Each weekday 2540 D N For operational process monitoring Total Suspended Solids 6 13 29 790 Jan 93 - Jan 08 Composite Weekly NOTE 2 2540 D Y Compliance sampling results UV transmittance - % at 254 nm - filtered

35 42 48 575 Apr 03 - Mar 05 Composite Each weekday 5910 B N

Carbonaceous BOD5 3 6 14 780 Jan 93 - Jan 08 Composite Weekly NOTE 2 5210 B Y Compliance sampling results Filtered Carbonaceous BOD5 2 5 12 215 Jan 93 - Feb 97 Composite Occasional 5210 B Y Non – routine process monitoring for planning purposes Chemical Oxygen Demand NOTE 4 50 70 95 2400 Jul 98 - Jan 08 Composite Each weekday Hach Method 8000 N For operational process monitoring Total Dissolved Solids 422 490 560 320 Sep 95 - Jan 08 Composite fortnightly 2540 C Y Recycled water monitoring pH NOTE 4 7.2 7.5 7.8 780 Jan 93 - Jan 08 Composite Weekly NOTE 2 4500 H+ Y Compliance sampling – results post chlorination. Alkalinity (as CaCO3) NOTE 4 95 140 190 70 Jul 02 - Jan 08 Composite Monthly 2320 B Y Recycled water monitoring Bicarbonate (as HCO3-) NOTE 4 120 170 226 240 Apr 99 - Jan 08 Composite fortnightly 2320 B Y Recycled water monitoring Electrical Conductivity (μS cm) 870 950 1000 150 Jul 98 - Jan 08 Composite Monthly 2510 B Y Recycled water monitoring Anionic Surfactants (mg/L MBAS) 0.1 0.2 0.4 310 Mar 97 - Jan 08 Composite fortnightly 5540 C Y Compliance sampling results Non-ionic surfactants (CTAS) - <1 <3 24 Apr 03 - May 03 Composite Occasional 5540 C Y Non – routine process monitoring for planning purposes Oil & Grease - <5 16 390 Feb 93 - Jan 08 Grab fortnightly 5520 B & D Y Compliance sampling results Ammonia Nitrogen NOTE 4 10 21 31 480 Jan 93 - Jan 08 Composite fortnightly NOTE 2 4500-NH3 G Y Compliance sampling – most data prior to N/deN upgrade Ammonia Nitrogen NOTE 4 9 18 28 2630 Jan 97 - Jan 08 Composite Each weekday 4500-NH3 B &C N For operational process monitoring – most data prior to N/deN upgrade Total Kjeldahl Nitrogen NOTE 4 12 22 33 2390 Jul 98 - Jan 08 Composite Each weekday 4500-Norg B N For operational process monitoring Total Kjeldahl Nitrogen NOTE 4 13 22 34 250 Jul 98 - Jan 08 Composite fortnightly 4500-Norg B Y Compliance sampling results Total Nitrogen NOTE 4 21 30 40 460 Jan 93 - Jan 08 Composite fortnightly 4500-NorgC & NO3 F Y Compliance sampling results Total Phosphorus 5.1 7.0 8.8 460 Jan 93 - Jan 08 Composite fortnightly 4500-P F Y Compliance sampling results Boron 0.1 0.21 0.37 68 Jul 02 - Jan 08 Composite Monthly 4500 B Y Recycled water monitoring Chloride 130 140 160 134 Jul 98 - Jan 08 Composite Monthly 4500 Cl Y Recycled water monitoring Fluoride 0.76 0.87 1.0 61 Jan 03 - Jan 08 Composite Monthly 4500 F Y Recycled water monitoring Sulphur as SO42- 46 51 61 85 May 02 - Jan 08 Composite Monthly 4500 SO4 Y Recycled water monitoring Selenium NOTE 5 - <0.001 0.001 61 Dec 02 - Jan 08 Composite Monthly 3500 Se Y Recycled water monitoring Sodium 96 110 120 133 Jul 98 - Jan 08 Composite Monthly 3500 Na Y Recycled water monitoring Calcium 14 17 22 133 Jul 98 - Jan 08 Composite Monthly 3500 Ca Y Recycled water monitoring Magnesium 8.2 9.3 10 133 Jul 98 - Jan 08 Composite Monthly 3500 Mg Y Recycled water monitoring Sodium Absorption Ratio 4.7 5.5 6.2 84 Jun 02 - Jan 08 Composite Monthly Calculated Y Recycled water monitoring Potassium 17 21 26 133 Jul 98 - Jan 08 Composite Monthly 3500 K Y Recycled water monitoring Lithium - <0.02 <0.02 61 Jan 03 - Jan 08 Composite Monthly 3500 Li Y Recycled water monitoring Beryllium - <0.001 <0.001 61 Jan 03 - Jan 08 Composite Monthly 3500 Be Y Recycled water monitoring Aluminium 0.12 0.23 0.47 68 Jul 02 - Jan 08 Composite Monthly 3500 Al Y Recycled water monitoring



Results Percentile NOTE 1 Sample Collection Details Method/Analysis Details Comments Parameter (generally mg/L, unless otherwise stated)

10th 50th (Median)

90th Approx. number

Data period Sample Type NOTE 8 Approx. Frequency

AWWA/APHA/WEF Std. Meth. No., unless otherwise stated

NATA

Iron 0.14 0.22 0.35 121 93 - 94 & Jul 02 -Jan 08

Composite Monthly 3500 Fe Y Recycled water monitoring

Cobalt <0.001 0.001 0.002 61 Jan 03 to Jan 08 Composite Monthly 3500 Co Y Recycled water monitoring Manganese 0.03 0.04 0.05 61 Jan 03 - Jan 08 Composite Monthly 3500 Mn Y Recycled water monitoring Arsenic <0.001 0.002 0.003 61 Jan 03 - Jan 08 Composite Monthly 3500 As Y Recycled water monitoring Zinc 0.04 0.06 0.10 140 93-95 & Sep 01 -

Jan 08 Composite Monthly 3500 Zn Y Recycled water monitoring

Molybdenum 0.002 0.004 0.007 61 Jan 03 - Jan 08 Composite Monthly 3500 Mo Y Recycled water monitoring Mercury (µg/L) <0.05 <0. 1 0.15 470 Jan 93 - Jan 08 Composite fortnightly 3500 Hg Y Compliance results – definitive percentiles difficult as LOD varies over period Chromium - <0.02 <0.05 406 Jan 93 - Jan 08 Composite fortnightly 3500 Cr Y Compliance results – definitive percentiles difficult as LOD varies over period Lead <0.005 <0.01 <0.05 467 Jan 93 - Jan 08 Composite fortnightly 3500 Pb Y Compliance results – definitive percentiles difficult as LOD varies over period Copper 0.01 0.016 0.03 397 Jan 93 - Jan 08 Composite fortnightly 3500 Cu Y Compliance sampling results Cadmium (µg/L) - <1 <10 479 Jan 96 - Jan 08 Composite fortnightly 3500 Cd Y Compliance results – definitive percentiles difficult as LOD varies over period Phenol (μg/L) - <1 <5 127 Jul 97 - Jan 08 Grab Monthly USEPA 8041 Y Compliance results – definitive percentiles difficult as LOD varies over period

Toluene (μg/L) - <1 <10 127 Jul 97 - Jan 08 Grab Monthly USEPA 8260 Y Compliance results – definitive percentiles difficult as LOD varies over period

Benzene (μg/L) - <1 <5 127 Jul 97 - Jan 08 Grab Monthly USEPA 8260 Y Compliance sampling results

PAH (μg/L)NOTE 6 - <8 <8 17 Dec 98 – Dec 07 Grab 6 monthly USEPA 8100 Y Compliance sampling results PCCD/F (pg/L ITEQ) NOTE 7 - <3 - 4 Dec 00 - Jun 03 Grab occasional Y Compliance sampling results E. coli (org/100 mL) 20 5000 150000 830 1992 - Jan 08 Grab Weekly NOTE 2 Report 71NOTE 3 Y Operational process monitoring – sampled after minimal chlorine contact time

ETP Reuse sample point (on the Outfall Rising Main near Thompsons Road, approx. 1.3km downstream of the Outfall Pump Station) E. coli (org/100 mL) 2 22 650 589 Jul 00 - Jun 03 Grab Weekly NOTE 2 Report 71NOTE 3 Y Reuse compliance monitoring – more chlorine contact time than final effluent

Notes:

1. Percentiles are given where appropriate. 2. Sampling day changes week to week to provide representative data. 3. Report 71, 1994, The Bacteriological Examination of Water Supplies, 4th Edition, HMSO, London. 4. Parameter changing due to secondary treatment area upgrade for nitrification and denitrification. 5. Most metals analysed using Inductively Coupled Plasma Method. 6. PAH is poly aromatic hydrocarbon. Results are the sum of individual compound concentrations with < results taken as half limit of detection 7. PCCD/F means poly chlorinated dibenzo dioxins and furans as toxic equivalents of 2,3,7,8 tetrachloro-dibenzo-p-dioxin. I-TEQ is an abbreviation of International Toxic Equivalent. 8. Current Sample Type: Composite = 24 hour flow paced composite by autosampler, Grab = single grab sample 9. Note that colour is only recorded in increments of ten


Appendix B: Project Drawings

• ATTP PROCESS FLOW DIAGRAM – SHEET 1 OF 2, J46-01-204 RevC • ATTP PROCESS FLOW DIAGRAM – SHEET 2 OF 2, J46-01-205 RevD • ATTP HYDRAULIC PROFILE - MAIN PROCESS, J46-01-206 RevC • ATTP HYDRAULIC PROFILE – FILTER BACKWASH, J46-01-207 RevB • ATTP CONCEPTUAL VIEW, G46-01-201 RevE • ATTP CONCEPTUAL PLAN VIEW, G46-01-202 RevE • ATTP CONCEPTUAL ELEVATION, G46-01-203 RevC • ATTP OUTLINE LAYOUT, G46-02-202 RevE • ATTP OUTLINE LAYOUT SHOWING FUTURE UF, G46-02-300 RevC

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