figure 26 pressure cement job equipment and setup (api, 2009)

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APLNG Project Hydraulic Fracturing Risk Assessment

P:\605X\60507973\8. Issued Docs\8.1 Reports\1. HF Risk Assessment\170306_APLNG Project Hydraulic Fracturing Risk Assessment_Rev1.docx Revision 1 – 06-Mar-2017 Prepared for – Origin Energy Resources Limited – ABN: 66007845338

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Figure 26 Pressure cement job equipment and setup (API, 2009)

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2.3.7 Well Integrity Testing

Following the drilling, casing and cementing of the well, isolation between each aquifer intersected by the well must be achieved to prevent both the leakage of groundwater between geological formations via the annulus of the well casing and the connection of the target coal seam from any overlying aquifers. This zonal isolation is achieved by ensuring sufficient cement is present throughout the annulus of the well casing, particularly in the depth intervals where natural aquitards are present. Evaluation is performed in accordance with Origin’s Well Integrity Standard (INT-1000-35-TS-013).

To verify the effectiveness of the casing cement job, a down-hole survey of the well is performed on all APLNG wells to be stimulated using a cement bond and variable density logging tool (CBL-VDL). Typically a gamma ray (GR) and Casing Collar Locator (CCL) tool is run concurrently with the CBL-VDL survey, so that the results can be correlated with any open-hole geophysical surveys performed (see Section 2.3.5). If following the CBL-VDL log the cement job is deemed to be inadequate the stimulation will not be conducted. A secondary (remedial) cement job may then be performed on the well, prior to any further works (including hydraulic fracturing) being conducted on the well.

The CBL tool is an acoustic device, the output of which can be used to infer quality of the bond between the casing and the surrounding cement; the cement bond quality can vary from a ‘good’ to ‘non-existent’ (free pipe). The tool transmits a continuous sound or vibration signal inside the casing and records the amplitude of the reflected signal. Casing that has a poor bond with the surrounding cement sheath produces a high amplitude returned acoustic signal, as most of the acoustic energy is reflects off the wall of the casing and surrounding fluid. Casing that has a good bond with the surrounding cement sheath will have a much smaller amplitude signal reflect to the tool, as a higher proportion of the acoustic energy is absorbed by the surrounding geological formation after it is transmitted via the better cement bond.

The VDL tool also provides a graphical representation of a reflected sonic waveform; however the transmitter and receiver are located at an increased spacing on the logging tool compared to the CBL transmitter/receiver. This allows the VDL to interpret the quality of the bond between the cement sheath and the surrounding geological formation.

The CBL and VDL tools are complementary and always performed concurrently. An example of a CBL-VDL output is presented as Figure 27. In this figure, the green line is a natural gamma plot (relevant to indicate permeability of the geology with respect to depth), the blue line is the CBL and the plot on the right is the VDL log, intervals of poor cement bond are represented by high peaks amplitude the blue plot and the thick black lines. Figure 27 Example of a Cement Bond Log, an integrity assessment technique

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2.4 Hydraulic Fracturing 2.4.1 Background

2.4.1.1 The CSG Extraction Process

The gas found in coal seams exists predominantly as methane and is generated as a by-product of coalification of lignite. Under natural conditions the methane is held to the coal surface by confining pore water pressure (adsorption). This confining pressure is reduced which enables gas molecules to be detached from the surface of the coal and migrate through to the natural fracture (cleat) system within the coal seam. Once in the cleat system the gas can flow through to the extraction well.

Depressurisation of coal seams is a process by which groundwater is extracted from the coal seam to reduce the pore water pressure within the coal seam. For the purposes of CSG extraction, the pore water pressure must be reduced to a level which permits desorption of gas from the coal, at which point the rate of water production declines. Depressurisation of coal for the purpose of CSG extraction does not typically result in the coal seam becoming unsaturated with respect to water.

This CSG dewatering and gas extraction process is illustrated in Figure 28. Figure 28 Typical production of water and gas over time in a coal seam gas well (IESC, 2014)

2.4.1.2 Function of Hydraulic Fracturing

Due to the high organic matter content of coal and the process of coal formation, the primary (or natural) permeability of coal is very low, typically ranging from 0.1 to 30 milli-Darcys (mD) (USEPA, 2004), this equates to a hydraulic conductivity of approximately 10-4 – 10-2 m/day for the flow of water.

At some locations within the project area, the permeability of the Walloon, Bandanna and Baralaba coal measures is too low for the coal seams to be economically dewatered; too many CSG production wells would be required to be installed for the extraction of the gas to be profitable. These ‘tight’ coal seams, typically with a permeability less than 20 mD, are candidates for hydraulic fracturing, a process utilised to increase the permeability, hence improve the efficiency of gas production from the coal seam.

The hydraulic fracturing techniques employed by the CSG industry aim to connect and/or extend the naturally occurring fractures within coal seam, thus increasing its permeability and connection of the wellbore to the coal. Under these more conductive conditions, water, free gas and gases adsorbed on the surface matrix of the coal can be more freely extracted.

2.4.1.3 Basis of Coal Permeability

Joints are fractures in a rock mass across which no displacement has occurred. They are commonly planar, occur in groups of sub parallel to parallel fractures called sets, and may extend both vertically

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and laterally for distances from as little as a few millimetres up to many tens of metres or more. Fractures in the coal which open a sufficient diameter to permit the transmission of free gas or liquid are referred to as ‘cleats’. These joints and cleats are typically more developed in areas that have undergone more intense structural deformation as a result of tectonic stress; they provide a significant proportion of the overall permeability of coal.

Joints and cleats are formed due to the effects of intrinsic tensile forces, fluid pressure, and tectonic stress. The intrinsic tensile force arises from the shrinkage of the coal matrix and the pressure which arises from hydrocarbons and other fluids within the coal. Conversely, tectonic stress is extrinsic and is the major factor that controls the geometric pattern of cleats. Face cleats extend in the direction of maximum in situ stress, and butt cleats extend in the direction of minimum in situ stress that is exerted at the time of their formation (see Section 2.2.2.3).

Larger in propagation distance, joints are found to extend over the whole or sections of the coal seam and are much less frequent than cleats. Joints are related to the tectonic movement. The frequency of joints increases rapidly when approaching shear structures and faults. Joints can cut across the lithological boundaries in the seam, but are in general limited to the seam thickness.

The water and gas found in the coals seams exists as stored free gas in the fracture system or adsorbed on the surface matrix of the coal. A typical coal seam fracture system is presented in Figure 29 and Figure 30. Figure 29 A typical coal seam fracture system

Source: University of Wyoming, http://www.gg.uwyo.edu/media/energy/fossilFuels/coal/formation/diagrams/coal-cleats.jpg

Figure 30 Example of naturally formed cleats within a piece of coal

Source: USGS, http://wy-mt.water.usgs.gov/pub/cbm3.jpg

http://www.gg.uwyo.edu/media/energy/fossilFuels/coal/formation/diagrams/coal-cleats.jpg

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2.4.1.4 Permeability of Coal Seams in Surat and Bowen Basins

APLNG has undertaken studies of the naturally occurring fracture patterns and permeability of the coal seams in the Walloon, Bandana and Baralaba coal seams, to develop an understanding of the prevalence of ‘tight’ coal seams (Section 2.2.3.3). These studies include:

• Analysing the existing fractures in well bores by using image logs.

• Commissioning seismic studies.

• Measuring permeability by undertaking drill stem tests.

• Developing conceptual tectonic models.

Using the outcomes of these studies APLNG plan and design their hydraulic fracturing programs.

2.4.2 Process

The hydraulic fracturing process is a series of operations performed on gas production well, to increase the permeability of the target coals seams in the immediate surrounds of the well.

The process consists of pumping fluid at a high pressure down the well then out into the target coal seam; the pressure of the fluid opens fractures within the coal seam. As the pressure is sustained the fractures propagate radially from the well, through the coal seam. Once optimal fracture propagation has been achieved, uniform fine grained sand or other propping material, referred to as “proppant” is pumped down the well and into the open fractures. The hydraulic fracturing fluid carries the proppant in suspension. Once the pumping of fluid ceases, the proppant is deposited in the coal seam fractures. As pressure on the coal seam is removed, the fractures are held open by the proppant, thus the permeability within the coal seam is increased. This allows both liquid and gas to flow more readily, improving the efficiency of gas recovery from the well.

2.4.2.1 In-Situ Differential Stresses

In-situ stress and the relative stress difference between geologic strata are important influences on fracture development. A formation underground has the weight of overlying strata and the constriction of lateral movement to create stress in the formation. These stresses occur in three dimensions, defining a maximum stress direction, intermediate stress direction, and minimum stress direction. These stresses are normally compressive and vary in magnitude throughout the Walloon and Bandanna coal measures, particularly in the vertical direction (from layer to layer).

The magnitude and direction of the stresses are important because they control the pressure required to create and propagate a fracture, the shape and vertical extent of the fracture, and the direction of the fracture. To initiate and propagate a fracture, the minimum stress must be overcome by the pressure of the fracturing fluid. In a uniform medium, the plane of a fracture is perpendicular to the direction of the minimum stress; i.e. fractures propagate parallel to maximum and intermediate stress, opening against minimum stress.

At depths of less than approximately 350 to 450m in the Surat Basin, the weight of the overburden is less than the horizontal stresses (i.e. the least stress is in the vertical direction) and so a horizontal fractures are likely to be created. At greater depths than these the direction of minimum stress is in a horizontal direction and so a vertical fracture is likely to be created.

2.4.3 Containment of Hydraulic Fracturing

Containment of hydraulic fracturing within the target strata is provided by lithologic stress barriers. Low stress rock (coals seams in Eastern Australia) provides a preferential fluid ‘sink’ during fluid injection, whereas high stress rock (interburden siltstone and shale) are barriers to fluid flow, i.e. the fluid/pressure wave is arrested at high stress barriers.

High and low stress rocks can be readily identified from dipole-sonic wireline logs, which are run prior to hydraulic fracturing. The dipole-sonic logs are calibrated using rock strength and/or closure pressure data from DFITS (diagnostic fracture infectivity tests), leak off tests or ISIP (instantaneous shut-in pressure). The calibrated dipole sonic logs are used to build a mechanical earth model is generated to identify stress barriers. The process of generating a mechanical earth model and equations specific to the Walloon Coal Measures are described in Brooke-Barnett et al. (2015) and Flottmann et al. (2013).

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The identification of stress barriers in combination with the controlled hydraulic fracture initiation depth (casing perforation interval) in pressure sink (coal) lithologies are used in hydraulic fracture design modelling software packages (e.g. StimPlan). Using stress barriers and initiation points as inputs the hydraulic fracture stimulation is then designed to limit pressures and the injected fluid volume for each hydraulic fracturing stage, to contain height growth into the target formations, thereby avoiding the potential for inadvertent injection into overlying or underlying aquifers.

A secondary safeguard is in place during the actual pumping, at the stage when pressure diagnostics indicate excessive height growth (e.g. related to small faults), that stage of hydraulic fracturing is stopped.

2.4.4 Design and Safe Operating Limits

The design principles used by APLNG aim to maximise the zone of influence of each hydraulic fracturing operation. The hydraulic fracturing radius of influence around a well is typically around 150 m, with a vertical influence of around 60m.

As part of the hydraulic fracturing design process for a production well, Origin engineers conduct hydraulic fracture modelling on each coal seam intersected by the well. From this modelling, the target coal seams to be hydraulically fractured are selected. Given the nature of the coal seam occurrence within the Walloon, Bandana and Baralaba coal measures (multiple beds of coal generally less than 20 m thick, with many being less than a metre, see Section 2.2.3.1), wells are typically hydraulically fractured in 3 to 12 discrete intervals, with each interval targeting a different layer of coal (see Figure 31).

For each hydraulic fracturing event, Origin engineers determine a safe operating envelope for injection pressure. The safe operating envelope is selected based on the following considerations:

• CBL results

• Mechanical earth model (see Section 2.4.3)

• Stimulation models (see Section 2.4.3)

• Historical tracer results

• Relevant legislation

• Internal and external standards

If at any stage during the process there is potential for deviation from the established pressure envelope, operations are ceased.

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Figure 31 Multi-zone CSG production well (APLNG, 2011)

2.4.5 Control

The hydraulic fracturing approach used to stimulate the coal seam gas wells differs across the project area due to local characteristics of geology and depth, effectiveness, production characteristics, or other factors. The fracturing approach affects the development (height, length, and width) of hydraulically induced fractures.

The choice of fracturing fluid (e.g. water or gel based) also affects fracture dimensions. APLNG has undertaken comparative tests of water and gel based fracturing fluid on fracture propagation and geometry. An example of this is where monitoring of fracturing (micro-seismic events) of the coal measures was undertaken on three wells within 500m of each other. The propagation of the fractures are tracked by using multiple geophones (essentially high sensitivity microphones) to detect the sound of the coal cracking and triangulating the location of the fracture.

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The results of a micro-seismic program performed by Origin are presented in Figure 32. Each point on the figure represents the location of a fracture that opened up during the fracturing that was large enough to be detected by the instrumentation. The gel-based hydraulic fracturing fluid (well Dalwogan 16) produced a more linear fracture pattern (almost north-south); while the water based fracturing programs (wells Dalwogan 13 and 14) produced a more uniform distribution fracture pattern (although still with a slight alignment parallel to the minimum stress direction). Figure 32 Data from micro-seismic assessment s of Hydraulic Fracturing Operations

The effects of these fluid-controlled actions interact with and are influenced by the physical properties, depths, and in-situ stress of the geologic formations being fractured (as discussed above). For example, if a hydraulically induced fracture has a relatively constant height due to a geologic layer acting as a barrier to fracture propagation, and the fracture is forced to grow and increase in volume (through an increased volume of fracturing fluid), the fracture will mainly grow in length.

The horizontal fracture geology is dependent on the range of factors discussed above, but current fracture analysis by APLNG indicates horizontal fracture geometry of 50 – 375 m from the well is typical.

Dalwogan 16

Gel-based fluid

Dalwogan 14

Water-based fluid

Dalwogan 13

Water-based fluid

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2.4.6 Operation

APLNG have completed hydraulic fracturing pilot programs in the Surat and Bowen Basins to refine their hydraulic fracturing designs and to improve productivity gains. These programs have allowed APLNG to improve their processes at each stage of the HFS. In conjunction with their selected service providers APLNG has implemented the use of market leading technologies that have; reduced the time required to complete the stimulation, improved safety standards, improved monitoring and mapping of the hydraulic fractures and have increased production rates.

The process of a hydraulic fracturing is conducted in the following sequential stages:

i. Site mobilisation and setup

ii. Casing pressure test to confirm integrity

iii. Well casing perforation

iv. Acid injection

v. Pad volume injection

vi. Slurry Volume injection

vii. Well flowback

viii. Zone isolation

ix. Repeat steps iii-viii for all zones

x. Suspend well ready for completion

Origin hydraulic fracturing specialists continuously monitor the progress of each hydraulic fracturing operation, to ensure that work is being conducted in line with APLNG policies and procedures. Monitoring is in real-time from a dedicated hydraulic fracturing room in Origin’s Brisbane office, in addition site visits will be conducted throughout the campaign.

2.4.6.1 Site Setup

The hydraulic fracturing operation requires various pieces of equipment, these may include:

• Data Unit – The control room from where the hydraulic fracturing contractor and APLNG supervisor manage and monitor all aspects of the hydraulic fracturing operation including: surface and downhole pressures, injection flow rates and volumes, injected fluid parameters and proppant concentrations.

• Temporary Above Ground Tank - A large open-topped tank with up to 7 ML storage capacity used to store water and supply it to the hydraulic fracturing operation as required. Panel tanks may also be used to temporarily store hydraulic fracturing flowback fluid from pilot hydraulic fracturing projects, prior to its treatment in water treatment plants.

• Proppant Trailer: a large sand storage and delivery trailer that holds the proppant prior to mixing in the Blender Unit.

• Hydration Units: pumps and tanks used to hydrate guar gum power with water to form a gel, this forms the basis of fluid viscosity in gel based hydraulic fracturing fluid.

• Blender Unit: pumps which mix the water, proppant and hydraulic fracturing chemicals on surface to achieve the required fluid consistency, prior to its injection into the well. Fluid is mixed “on-the-fly” as required throughout pumping procedures.

• High Pressure Pumps: pumps which inject the hydraulic fracturing fluid mixtures from the Blender Unit down the well, via the surface lines and hydraulic fracturing wellhead or coiled tubing unit.

• Hydraulic Fracturing Wellhead and Surface Lines: a network of pipes and pressure control valves that connect to the high pressure pumps and coiled tubing unit to the well.

• Coiled Tubing Unit (if required): a large length of coiled steel pipe that can be temporarily installed in the well to convey hydraulic fracturing fluid from surface to the target depth interval to be fractured. The coil can use a number of bottom hole assemblies (BHAs) to deploy the stimulation.

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• Flowback tanks: tanks with approximately 20,000 to 80,000 Litre storage capacity which are used to temporarily hold all fluid and proppant that flows back from the well following the hydraulic fracturing procedure. These tanks may be open-topped or sealed, depending on the requirements of the hydraulic fracturing operation.

A typical hydraulic fracturing operation site setup is presented in Figure 33.

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Figure 33 Example of a Hydraulic Fracturing Operations Site Setup (API, 2009)

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2.4.6.2 Well Casing Perforation

The perforation of well casing is the process by which perforations (holes) are created in the casing of the well at the specific depth intervals, which correspond with the target coal seam. This process hydraulically connects the well to the target coal seam.

The total vertical length of the perforation interval is dependent on the thickness of the target coal seams. The perforations are generally positioned to be slightly below the midpoint of the coal seam being fractured to allow for some upward propagation of the fracture.

APLNG currently use two methods for the perforation of well casing for their hydraulic fracturing operations. The first method uses a perforating gun tool that is loaded with specialised explosive charges. The tool is lowered into the well to the desired perforation interval on a wireline and detonated remotely from surface (this method is illustrated in Figure 34). Alternatively, APLNG also use the method of hydraulic jetting, whereby a high pressure jet of water and fine grained sand is used to cut holes in the casing. Figure 34 Perforation gun charge (API, 2009)

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2.4.6.3 Fluid Injection Stages

Once the well has been perforated in the depth interval that is to be hydraulically fractured, a series of fluid injection stages are performed.

2.4.6.3.1 Injection and Isolation Techniques

Following perforation of the target zone, injection of fluid commences. The injection pressure, injection rates, slurry volumes, fluid viscosity, and proppant concentration are monitored in real-time during each injection, to confirm the success of the procedure and if necessary make adjustments to one of the monitored parameters.

In addition to monitoring data from the surface equipment, downhole pressure information is also recorded and reviewed during the hydraulic fracture stimulation operation. Down-hole pressures are calculated based on wellhead pressure, fluid density, casing diameter and the depth to the target formation. When a coiled tubing unit is used as part of the operation pressure is monitored: inside the casing above the top packer of the tool, inside the coiled tubing delivering the fluid and inside the wellhead at surface.

Once the predetermined volume of fluid has been injected into the well the operation advances to the next stage of injection.

The perforation zones are isolated by either a coiled tubing unit with packers, a bridge plug set by a wireline operator, or by a baffle and ball-drop system. In the case of bridge plugs and baffles, once the entire hydraulic fracturing operation is complete for a well a completion rig drills-out the bridge plugs or baffles that were installed for the hydraulic fracturing operation, to clear them from the well.

2.4.6.3.2 Acid Injection

Following casing perforation and prior to stimulation, an acid solution can be spotted across the perforated intervals. Acid spotting improves the injection rates during the hydraulic fracture stimulation operation. Acid spotting serves to dissolve any calcite (calcium carbonate) naturally present in cleats of the target coal seams and clean any skin damage in and around the casing perforation, which may have been remnant from the casing perforation procedure.

The acid spotting process comprises the pumping of a pH-stabilised 15% hydrochloric acid solution down the well, through the well perforations and out into the into the target coal seam.

The acid pumping stage is concluded when the injection pressure is noted to decrease whilst the injection pumping rate remains constant, i.e.: as the flowpath for the fluid through the perforations is widened by the clearing of the remnant cement in and around the perforations the injection pressure required to maintain the selected pumping rate decreases.

Following spotting, the acid solution is diluted and pushed further into the coal seam by the water injected during the next stage of the hydraulic fracturing process, the Pad Volume Injection.

Based on the relatively short duration of acid spotting and the dilution of the acid by the fluids injected subsequently, the potential for the integrity of the annular cement seal to be impacted by the acid spotting is considered low and localised to the immediate vicinity of the perforations.

2.4.6.3.3 Pad Volume Injection

The pad volume injection is the first hydraulic fracturing fluid to be pumped into the target coal seam. The pad volume is mixed on surface on the fly as the injection is continuing. The injection initiates the opening and propagation of fractures within the perforated target interval depths.

Depending on the viscosity of the fluid required to hydraulically fracture the target coal seams, water, linear gel or cross-linked gel is used as the base for the hydraulic fracturing fluid. Gel-based fluid is used to improve the proppant carrying capabilities as well as improve the fracture width growth over water.

The addition of guar gum (the crushed endosperm of guar beans) or cellulose to the water forms the basis of a linear gel. If further viscosity is required a cross-linking compound, such as borate, is added to the linear gel to form a cross-linked gel. The cross-linking of the guar gum or cellulose molecules increases the viscosity of the fluid by linking lower molecular weight polymers, to effectively create a larger, more rigid polymer chain.

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To prepare the gel solution, guar gum or cellulose powder is hydrated for several minutes in a baffled tank on site. After allowing the guar gum or cellulose powder to hydrate for several minutes the viscosity of the linear gel fluid is ~3 centipoise (cP), marginally higher than that of water (1 cP). If the gel is cross-linked by the addition of a compound such a borate, the viscosity of the fluid increases to 300 cP.

Once prepared the pad volume fluid is prepared it is injected into the coal seam at a rate of approximately 4 - 25 barrels per minute at a differential pressure at surface of up to 5000 psi. The injection pressure is increased until a sudden pressure drop is registered on the pressure gauge; this represents the initial opening of the fracture in the coal seam. The injection of the pad volume is then continued, propagating the fracture network up to 375 metres from the well. At this point the injection fluid is switched from the pad volume fluid to the slurry volume fluid.

2.4.6.3.4 Slurry Volume Injection

At the conclusion of the pad volume proppant is added to the stimulation fluid to form an injection slurry fluid. This switch is performed whilst pumping is continuing, such that pressure is not released from the coal seam (which would allow the fractures to close).

The fluid injected during the slurry volume stage is typically comprised of water, proppant (typically graded quartzose or silica sand), and chemical additives (additives to prevent the swelling of clay interbedded between coal seams, guar gum and acid buffers). Several different sized proppant particles may added to the slurry in different phases depending on the reservoir being stimulated. Typical proppant mesh sizes used by APLNG may include:

- 100 mesh sand (< 150 μm diameter grainsize)

- 40/70 sand (212 – 420 μm diameter grainsize)

- 20/40 sand (420 – 840 μm diameter grainsize)

- 16/30 sand (590 – 1190 μm diameter grainsize).

Once the designed volume of proppant has been injected into the target coal seam, the addition of proppant to the slurry is ceased and the well is flushed with fluid to displace all proppant into the reservoir.

If a gel based fluid has been used, a gel ‘breaker’ compound is then added to the slurry that is being injected into the coal seams. The breaker is comprised of an oxidant or enzyme which breaks the long chains of the gel molecules. This significantly reduces the viscosity of the gel fluid in the coal seam fractures (reduced from 300 cP to <10 cP), reducing so the fluid can be produced back easily. The complete list of chemicals used by APLNG during hydraulic fracturing and the concentrations at which they are used is detailed in Section 2.4.7.

2.4.6.4 Initial Well Flowback

At the cessation of pumping the required volumes of fluid, the target coal seams, which have become pressurised during the hydraulic fracturing operation, may be allowed to depressurise. This is achieved by closing the injection valve and opening the discharge valve on the wellhead, allowing the well to ‘flowback’, i.e.: flow back fluid to surface.

The initial flowback fluid may contain fluid from the pad and slurry volumes as wells as groundwater native to the coal seam. Fluid flowed back from the well is temporarily stored in on-site flowback tanks, when these tanks become full the fluid may transferred directly to an APLNG water treatment plant or into larger ring tanks before finally being processed through an APLNG water treatment plant. The well is allowed to flowback until the majority of solid particles (mostly proppant) have cleared from the fluid flowing back, up to several hours. The discharge valve on the wellhead is then closed, once again, shutting in pressure in the well.

2.4.6.5 Hydraulic Fracturing Fluid Management

Source Water

Source water (used to mix the hydraulic fracturing fluid on site), is comprised of either post-RO permeate water from an APLNG water treatment plant or groundwater from a nearby bore. The source water is stored on site in ‘Grizzly Flexiponds’. These are double lined, with potentially the addition on

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KCl for pH control. The time frame on site for these ponds for development areas is limited as they are decommissioned after completions activities.

Flowed-back Fluid

Control of the fluids used for hydraulic fracturing is carefully managed by APLNG throughout the hydraulic fracturing and well commissioning process.

The process for managing fluid differs between hydraulic fracturing campaigns in pilot and operational fields.

• For pilot campaigns, the flow path of hydraulic fracturing fluid during initial flowback of the well is illustrated in Figure 35. The flow path of hydraulic fracturing fluid following its commissioning is illustrated in Figure 36.

• For campaigns in operational areas the flow path of the flow back fluid is the same as for the pilot area wells, except instead of storing the flowed back fluid in open top ring tanks it is transferred from the well to an APLNG water treatment plant via a buried pipeline.

2.4.6.6 Commissioning Well Flowback and Well Development

Following the hydraulic fracturing of the final target interval all fracturing equipment is removed from the site and the well is shut in. Surface infrastructure is connected to the well, this can include:

• a gas/fluid separator;

• buried pipes to convey the gas and water which flows from the well; and

• a down-hole artificial lift pump (e.g. progressive cavity or electric submersible) and an associated generator, if the well has insufficient pressure to flow at surface without artificial lift.

Once the surface infrastructure is connected to the well, the well is again flowed back. Fluid passes from the well, through the gas separator , then on to an APLNG water treatment plant or open top ring tank, depending on whether the campaign is in a pilot or operational area (see Section 2.4.6.5).

As the well is flowed back hydraulic fracturing fluid is flowed back to surface, however an indeterminable volume of hydraulic fracturing fluid may never return to surface, held in fractures far from the pumping well. A discussion on the cumulative impacts of hydraulic fracturing chemicals which remain in the coal seam is included in Section 3.5.

2.4.6.7 Addition of Tracers to Slurry Volume

Radionuclide Tracers

In some historical hydraulic fracturing campaigns Origin added small concentrations of chemicals or insoluble radionuclides to the slurry volume as a tracer material. The addition of tracers is a hydraulic fracturing assessment technique used to measure numerous parameters including; the vertical extent of the hydraulic fracturing in the well after the conclusion of the operation (see Section 2.4.8.2) and contribution from producing zones. The chemical tracers which are used are inert. The radionuclide tracers consist of insoluble ceramic beads that have been embedded with radionuclides. The environmental hazard of using radioactive tracers as part of hydraulic fracturing operations is discussed in Section 6.2 .

Chemical Tracers

APLNG intend to use chemical tracers for the upcoming WAP and Varidel campaigns, detailed in Section 10.5.2.

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SEPERATOR

Fluid to ring tank

NOTE: Particulate materials remain in separator

for the duration of Ramyard pilot trial

OPEN TOP RING TANK ~ 6 ML Capacity

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2.4.7 Fluid Systems

Hydraulic fracturing fluid is typically around 97% (v/v) water and proppant and approximately 3% (v/v) chemical additives introduced to improve the process of hydraulic fracturing. The composition of fracturing fluids varies in order to meet the specific needs of each hydraulic fracturing operation based on local geology. Chemical additives may consist of acids, surfactants, biocides, bactericides, pH stabilisers, gel breakers, clay, corrosion and scale inhibitors, however not all additives types are used in every fracturing job.

An inventory of the chemicals used by these contractors for historical hydraulic fracturing campaigns in Spring Gully and pilot areas is presented in Table 8. Hydraulic fluid systems for all fracturing new hydraulic fracturing campaigns will be presented in the Appendix, in a campaign-dedicated risk assessment. All fluid systems historically and for any current campaigns are also summarised in Appendix C.

2.4.7.1 Mass Balance

A mass balance of all fluid systems historically and currently used for hydraulic fracturing operations is included in Appendix C.

The mass balance describes the concentration of the chemical components of each fluid system, in terms of weight and volume. The concentration of each chemical injected into the coal seams is calculated, in terms of:

• Weight for weight (w/w), i.e. kg/kg

• Volume for volume (v/v), i.e. L/L

• Weight per volume (w/v), i.e. mg/L

For the (w/w) and (v/v) calculation the weight/volume of the proppant material is included in the total weight/volume of the fluid system. In the (w/v) calculation, the volume of the proppant is not included in the total volume, so as to not under-represent the concentration of each chemical relative to the overall fluid system; instead the total volume used to calculate chemical concentration (w/v) includes only liquids.

The mass balance also estimates the concentration of each chemical that will be returned to surface during the flowback of the hydraulically fractured well, based on a upper and lower estimate of 20% and 60% mass recovery.

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Table 8 Inventory of chemicals used in APLNG hydraulic fracturing campaign (Spring Gully and Pilot areas)

Additive Type Product CAS Number Hydraulic Fracturing Fluid Systems Stimulation Provider Hydraulic Fracturing Fluid Systems

Water-Based Cross Linked Gel Cross Linked Gel Linear Gel Water-Based Cross Linked Gel

Base

Fl

uid

and

Prop

pant

Water 7732-18-5 x x x x x x Nitrogen 7727-37-9 x Silicon dioxide (quartz / sand) 14808-60-7 x x x x x x

Wat

er c

ondi

tioni

ng: M

icro

bial

and

pH

Cont

rol

Diatomaceous earth, calcined 91053-39-3 x Magnesium nitrate 10377-60-3 x Citric Acid 77-92-9 x x 5-chloro-2-methyl-2h-isothiazolol-3-one(Methylchloroisothiazolinone) 26172-55-4 x Coffee extract 68916-18-7 x x 2-methyl-2h-isothiazol- 3-one(Methylisothiazolinone) 2682-20-4 x Cristobalite 14464-46-1 x Sodium hypochlorite 7681-52-9 x Sodium hydroxide (caustic soda) 1310-73-2 x x x Sodium carbonate 497-19-8

Hydrochloric acid 7647-01-0 x x Gelatins 9000-70-8 x Glutaraldehyde 111-30-8 x Glycerine/Glycerol 56-81-5 x x Acetic acid 64-19-7 x x x x Tributyl tetradecylphosphonium chloride 81741-28-8 x x

Clay

Co

ntro

l

Potassium chloride 7447-40-7 x x

Flui

d Vi

scos

ity C

ontr

ol

Guar gum 9000-30-0 x x x Hemicellulase Enzyme 9025-56-3 x x x x MEA borate 26038-87-9 x x Sodium chloride 7647-14-5 x Potassium Hydroxide 1310-58-3 x Aluminium Sulfate 10043-01-3 x Maltodextrin 9050-36-6 x Sodium Carboxymethyl Cellulose 9004-32-4 x Sodium Lauryl Sulfate 9004-82-4 x Sorbitan, monododecanoate, poly(oxy-1,2-diethanediyl) 9005-64-5 x Sulphuric Acid 7664-93-9 x Lactose 63-42-3 x x Shellac, ammonium salt 68308-35-8 x x Talc, Magnesium Silicate 14807-96-6 x x Sodium bisulfite 7631-90-5 x x Sodium polyacrylate 7/04/9003 x x Diammonium peroxidisulphate 7727-54-0 x Non-crystalline silica (impurity) 7631-86-9 x Potassium borate 1332-77-0 x 1-Propanaminium, 3-amino-n-(carboxymethyl)-n,n-dimethyl-n-coco alkyl 61789-40-0 x

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2.4.8 Monitoring and Assessment

Part of the stimulation design includes the delineation of an acceptable safe operating pressure envelope. The key information provided in this envelope is the minimum pressures and maximum rates acceptable. If operations exceed these parameters it is possible that a loss of fracture integrity has occurred.

During the hydraulic fracturing operation the injection pressure and fluid volume is continuously monitored to immediately identify a condition that would indicate the loss of integrity of the well casing or coal seam overburden layer (see Section 2.4.5). In the event a potential loss of integrity is observed the operation will be ceased immediately.

In addition to this monitoring, APLNG monitor the pressure, flowrate and the chemistry of water flowed back from gas wells throughout their production phase for operational reasons; this data also can be used to confirm the hydraulic fracturing has not created a hydraulic connection between the coal seams with adjacent aquifers (see Section 2.2.4.3.3).

APLNG sometimes conduct field-based studies which measure the vertical and lateral extent of the fractures that created during an APLNG hydraulic fracturing operation, these are discussed below.

2.4.8.1 Tiltmeters

A tiltmeter is a device that measures the change in the inclination in the earth’s surface. A typical surface monitoring array consists of 15 to 50 or more surface tiltmeters, plus two or more GPS stations. Vertical displacement contours are determined by integrating the slope measurement from several tiltmeters and calibrated with an accurate GPS or level survey reading. Advances in the computer software and sensitivities of tiltmeter instruments since their inception in the 1980s allows the devices to measure changes of inclination as small as a nanoradian and in real-time. APLNG use the device to map and assess the horizontal propagation of the hydraulic fracturing in their project area. The results are used to improve the efficiency of future hydraulic fracturing programs.

2.4.8.2 Tracers

The addition of small concentrations of either radioactive or chemical tracers to the hydraulic fracturing proppant material is an industry-standard technique used by APLNG measure the vertical extent of fracturing that occurred during a hydraulic fracturing operation.

In the case of radioactive tracers, insoluble ceramic beads which have been embedded with radionuclides are added to the slurry volume which is injected into the well. The tracer beads have the same density as the proppant material; hence they are held in suspension in the fluid, and travel with the proppant. Different radionuclides are used for each fracture interval in order to distinguish the extent of fracturing around each hydraulically fractured interval. Following the completion of hydraulic fracturing a wireline log (geophysical survey) of the well is conducted to assess the extent of proppant and tracer placement, which corresponds with intervals with fractures propped open. Queensland Heath approves the use of radioactive tracers on a case by case basis, in accordance with the Radiation Work Program provided by APLNG .

2.4.8.3 Production Well Pressure and Water Quality Monitoring

During the hydraulic fracturing operation the injection pressure is continuously monitored to immediately identify a condition that would indicate the loss of integrity of the well casing or overburden formation. The injection pressure is the principal indicator of a loss of the integrity of either the well casing or coal seam overburden layer.

An unexpected drop in injection pressure could be indicative of a hydraulic connection forming between the target coal seam and an adjacent aquifer (i.e. the failure of the overburden formation), a failure of the well casing, or a new fracture being propagated inside the coal seam.

The determination of whether a pressure drop is indicative of a loss of containment is based on the safe operating pressure envelope, determined by APLNG for each well. If the fracturing pressure drops below the safe operating pressure envelope, hydraulic fracturing is immediately ceased.

Following the completion of the hydraulic fracturing operation and the commissioning of the production well, formation pressure, flowrates and the quality (chemistry) of water flowed back from gas wells is continually monitored. A change in pressure or flow rate is used as a primary indicator of potential loss


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of containment warranting further investigation. A change in water chemistry may take some time to become apparent in the groundwater flowing back from the well, hence changes in water chemistry is used as a secondary indicator warranting further investigation (see Section 2.2.4.3.3)

2.4.8.4 Landowner Bore Assessments

In accordance with the Queensland Water Act (2000), APLNG conducts baseline assessments of all landholder water bores (when landholder permission is granted) in areas where petroleum and gas production testing or production has commenced or will soon commence.

The assessments represent a point-in-time census of individual bore water level, quality, usage and condition. The APLNG landholder bore baseline assessment program was completed in early 2013. Over 900 bores were visited as part of the three year program.

In accordance with EA conditions, landholder bores within required offset distances will be reassessed prior to hydraulic fracturing.

2.4.9 Comparison to International Best Practice

Over the last 60 years the hydraulic fracturing process has been continually refined within the oil and gas industry. Modern hydraulic fracturing techniques improve the effectiveness of the fracture stimulation, whilst limiting environmental harm. The American Petroleum Institute (API) documents developed over this period provide the industry best practice guidance for the hydraulic fracturing operations and the management of hydraulic fracturing fluids.

The API is the primary distributor of industry standards and guidance, primarily through their recommended practises, technical reports and standards publications.

The API specifications relevant to hydraulic fracturing are presented in Figure 37.

The API has also published three guidance documents that outline best practices to minimise environmental impacts associated with hydraulic fracturing. These are:

1. Hydraulic Fracturing Operations – Well Construction and Integrity Guidelines

This document focuses on groundwater protection related to drilling and hydraulic fracturing operations.

2. Water Management Associated with Hydraulic Fracturing

This document focuses on the management of water used for hydraulic fracturing.

3. Practices for Mitigating Surface Impacts Associated with Hydraulic Fracturing

This document outlines potential impacts to surface waters, soils, and other ecosystems and describes best practises to mitigate these environmental impacts. APLNG and APLNG contractors adhere to the API guidance and ‘Best Practice’ specifications for the design and implementation of all hydraulic fracturing operations that are conducted for the APLNG Project. In addition, APLNG complies with all regulatory directives regarding hydraulic fracturing process.

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Figure 37 API Guidance/Best Practices supporting Hydraulic Fracture (2013, API)

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3.0 Risk Identification

3.1 Overall Approach The following Risk Assessment Approach diagram illustrates the key activities associated with the environmental risk assessment and how each of these tasks fits into the overall assessment of risks. Key site-specific summary information is provided in the inserts within the flow chart, to provide an overview of the HHRA works presented herein. Figure 38 Risk Assessment Approach

Risk Assessment Approach

Issue Identification This section involves the identification of key issues amenable to the risk assessment and includes a description of the current environmental setting, detailed geological and hydrogeological information, gas well integrity and a description of the hydraulic fracturing process including an identification of the

constituents of the hydraulic fracturing fluid.

Exposure Assessment This section identifies the human populations and environmental receptors (where relevant) that may be exposed to the COPC/ COPEC and outlines the mechanisms (exposure pathways) by which these receptors may be exposed. Human Health is assessed via a quantitative estimate of exposure and intake of the chemicals of potential concern. Environmental receptors are also assessed, based on a review of the mechanisms and pathways by which the COPEC may migrate and have an adverse effect on the environment.

Hazard and Toxicity Assessment This section involves the collection and analysis

of relevant toxicological data. • Hazard Identification – An evaluation of

the environmental hazard of the constituents of the hydraulic fracturing fluid based on a persistent, bioaccumulative and toxic (PBT) substances assessment based on the Australian and EU Reach Criteria Methodology. Chemicals of Potential Concern (COPC) are identified

• Toxicological Assessment – Identifies the most appropriate toxicity values for the COPCs which can be used to provide quantitative estimates of risk to human health.

Risk Characterisation Human Health - This section uses the toxicity values and quantitative estimates of chemical intake to

provide a quantitative estimate of the potential health risks associated with exposure to the COPC. Environmental - This section provides a quantitative assessment of risks to the environment from the

COPEC. The outcome of the risk characterisation is site-specific and is based on the available data,

limitations and uncertainties outlined in the above tasks.

Human Health Receptors: Workers and Trespassers on and off-site.

Potential Pathways: Inhalation and direct contact Environmental

Receptors: Flora and fauna on- and off-site (where present); nearby surface water receptors (creeks, streams

and rivers). Pathway: Direct contact and off-site migration in

groundwater

Toxicity data sourced from: ADWG, ANZECC, WHO, USEPA, TPHCWG,

RIVM, ATSDR, NICNAS, OECD ECHA and ECJRC,

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3.2 Problem Formulation 3.2.1 General

As described in NEPC (2013), the problem formulation establishes the goals and focus of the assessment. Additional products of the problem formulation stage are a conceptual model that identifies the stressors, sources, receptors, exposure pathways and potential adverse human health effects that the risk assessment will evaluate, and a work plan that outlines the approaches that will be used in the risk assessment.

3.2.2 Issue Identification

In the framework of this assessment, receiving environments are those which have the potential to be affected by hydraulic fracturing within the project area. Based on the information provided in the Receiving Environment Section (Section 2.2), APLNG Well Integrity Section (Section 2.3) and the Hydraulic Fracturing Section (Sections 2.4), the potential hazards to the project area receiving environments associated hydraulic fracturing (as identified in the EA conditions) that require further assessment are the following:

• The exposure of workers, trespassers or the environment to potentially hazardous concentrations of hydraulic fracturing chemicals as a result of the loss of containment, operational spills and leaks;

• The potential for release of hazardous gases from the CSG well following hydraulic fracturing;

• The potential release of dust from hydraulic fracturing activities;

• Contamination of groundwater in aquifers overlying or underlying the target coal seams;

• Contamination of groundwater in the target coal seams that is accessed by landholder bores;

• Migration of remnant hydraulic fracturing fluid or chemicals to springs, adversely affecting water quality; and

• Hydraulic fracturing triggering earthquakes and/or reactivation of geological faults.

3.2.3 Objective

Based on the information presented in the sections above, the objective of this assessment consists of the following:

• A qualitative assessment of the environmental risks to the receiving environment associated with the injection of hydraulic fracturing fluids into the coal seams of the Walloon, Bandanna Formation and Baralaba Coal Measures in the Bowen and Surat Basins. A qualitative assessment of the potential risks to terrestrial and human health toxicity associated with the process of hydraulic fracturing and the management and storage of flow back fluids above grade; and

• A quantitative assessment of the potential risks to human, aquatic, terrestrial receptors associated with the management and storage of flow back fluids.

The potential complete exposure pathways will be identified through the qualitative evaluation process, and quantitative assessments will then be completed only on those potentially complete exposure scenarios. Through the process of both qualitative and quantitative risk assessment, appropriate management controls will be identified for the management of potential risks.

3.3 Qualitative Risk Assessment 3.3.1 Receptors and Exposure Pathways

This section identifies the receptors who may be exposed to the COPC identified for the hydraulic fracturing activities, and outlines the mechanisms (exposure pathways) by which these populations may be exposed.

For an exposure pathway to be considered to be complete there must be all of the following:

• Source of COPC - how the chemical got into the environment;

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• A transport media - how the chemical moves or migrates through the environment (soil, water or air);

• An exposure point - how human and environmental receptors can come into contact with the chemicals; and

• An exposure route - how the chemical could enter the body of the receptor (e.g. inhalation, ingestion or dermal contact).

If any one of these steps (source, transport media, exposure point or route) is not present, then the exposure pathway is incomplete and, hence, further assessment of risks is not required.

In the cases where the exposure pathways are complete, or have the potential to be complete, then the pathways can be considered significant or less significant. The significance of the exposure pathway depends on the nature of the impact present and the evaluation of the likely exposure concentrations that may be associated with the pathway.

3.3.2 Risks and Mitigation Measures

Table 9, below discusses the potential risks identified in Section 3.2.2 and the mechanisms by which adverse impacts are proposed to be controlled/managed.

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Table 9 Qualitative human health and environmental risk assessment and consideration of the need for Quantitative risk assessment

Identified Potential Hazard

Hazard Causes and Consequences Risk Mitigation Measures Warrants further consideration in this Risk Assessment

Reason for carrying forward the potential hazard into the subsequent Quantitative Risk Assessment

Surf

ace

Env

ironm

ent The loss of

containment of chemicals used for hydraulic fracturing

Exposure of workers, residents or the environment to potentially hazardous hydraulic fracturing chemicals, resulting from loss of containment occurring: • Whilst in transit to site;

• During the mixing of hydraulic fracturing fluid on

site; or • (In diluted form) during the storage and transport

of well flowback fluid.

Origin implement a range of engineering and operational control measures to ensure the risk of hydraulic fracturing fluid spills are minimised during hydraulic fracturing operations, including during transport to and from the wellsite and during the flowback of hydraulic fracturing chemicals from the well. These control measures include:

• Adherence to the material storage and transport requirements as stipulated on the chemical Safety Data Sheets (SDS).

• Adherence to the Transport of Dangerous Goods by Road Regulations (for chemicals classified as a ‘Dangerous Goods’).

• Ensuring chemicals remain in their original containers and are not decanted into smaller containers which may not be fit for purpose.

• During hydraulic fracturing operations, the use of secondary containment beneath all pipework connections and equipment holding or pumping chemicals.

• Using fit for purpose flowback fluid storage tanks. Conducting regular integrity checks of fluid storage tanks, during commissioning and use. Ensure adequate freeboard is maintained at all times.

Yes

The evaluation of the risk to workers involved in the operation of well stimulation activities (including transportation of the COPC to the site) is not considered warranted in the subsequent sections of this risk assessment, as it is addressed via the implementation of appropriate occupational health and safety procedures and management plans.

Further consideration is warranted regarding the risk of above ground exposure relating to the handling and storage of hydraulic fracturing chemicals and flowback water. This is addressed in Section 4.5.

Further assessment is warranted regarding the risk associated with the potential and actual concentrations of COPC in flow back water; and the presence of other COPC that may have been liberated during the hydraulic fracturing operations. This is addressed in Section 4.5.

Further assessment is warranted regarding the chemical and physical properties of the constituents used in hydraulic fracturing fluids that result in the potential for these chemicals to be present in flow back water and to be of concern in relation to potential acute or chronic risks. This is addressed in Section 4.5.

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Loss of containment of radioactive materials sometimes used during hydraulic fracturing operations

Radioactive substances are occasionally used in low concentrations as a tracer material for the assessment of the vertical extent hydraulic fracturing activities. Exposure of workers, residents or the environment to potentially hazardous radioactive material, resulting from loss of containment occurring:

• Whilst in transit to site;

• During the mixing of hydraulic fracturing fluid on site;

• (In diluted form) during the storage and transport of well flowback fluid; or

• During disposal from site.

When radioactive materials is used as part of the hydraulic fracturing operation, additional risk mitigation measures are implemented, these include:

• Implementation of safety procedures specific to the containment, use and disposal of radioactive material.

• Preparation of a Radiation Safety and Protection Plan (RSPP), approved by Queensland Health.

Yes Despite the control measures put in place to minimise the risk of radioactive material spills, the potential pathway for exposure persists, hence the risk is not eliminated. Further assessment is warranted regarding the risks of using radioactive material during hydraulic fracturing operations. This is addressed in Section 6.2

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Harm to the environment due to the release of fugitive emissions from hydraulically fractured wells.

Release of hazardous gases from the CSG well at surface following the hydraulic fracturing of a well; e.g. if the hydraulic fracturing injection pressure were to open a micro annulus in the production casing annular cement seal, from the coal seams to surface.

Origin’s Well Design protocols mandate the use of both surface and production casing sections. In the unlikely event that a micro annulus was opened in the production casing annular cement seal from a coal seam to ground surface, any gas that migrated through that pathway would be contained by the wellhead which is fastened to the top of the surface casing, encapsulating the top of the production casing and production casing annular seal (see Section 2.3.3). Prior to hydraulic fracturing, Origin evaluates the quality of the cement seal around the production casing of every well by reviewing CBLs performed on the wells. If Origin considers the cement seal of a well to be inadequate for hydraulic fracturing, that well is not hydraulically fractured. If there is uncertainty within Origin as to the suitability of the cement seal of a well, the CBL is reviewed by an independent third party, if they consider the cement seal of a well to be inadequate for hydraulic fracturing, that well is not hydraulically fractured.

No Origin has in place procedures which: • Reduce the likelihood that wells leak

gas through cement seals (the CBL review process)

• Eliminate the pathway for gas to leak from a coal seam to surface via the production casing cement seal (Origins Well Design protocols).

These measures mitigate the risk associated with gas leaking from coal seams to surface as a result of hydraulic fracturing.

Harm to residents or fauna/flora due release of dust from hydraulic fracturing activities

During the hydraulic fracturing process, certain fluid additives may be present which pose a human health risk due to inhalation due to dust generation. Crystalline silica (sand) is an example of a potential risk additive.

Chemical blending operations are carried out in closed system tanks, minimising exposure to workers onsite and the potential for creating windblown dust, which could impact residents or flora/fauna. With this control in place, the risk for dust created by hydraulic fracturing to harm residents or fauna/flora is considered as low.

No Origin’s work procedures (notably the blending of chemicals in closed-system tanks) removes the exposure pathway to workers, residents, flora and fauna, hence no further hazard assessment is warranted.

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Harm to residents or fauna due to noise or vibrations from hydraulic fracturing operations

Significant noise and vibrations can be created during hydraulic fracturing operations by the pumps, blenders, generators used to conduct the operation. This noise has the potential to harm residents or fauna in the short or long term.

During the hydraulic fracturing planning phase, Origin models the noise that will be produced during hydraulic fracturing operations. If residents’ houses/buildings are considered to be located in an area in which they may be disrupted by the noise of the hydraulic fracturing operation, Origin temporarily relocate residents for the course of the works on the well (typically several days).

Yes The potential pathway for noise to harm residents is removed by the protocols Origin has in place (noise modelling and relocation).

Further assessment is warranted regarding the risk of noise or vibrations harming fauna. This is addressed in Section 6.1.

Subs

urfa

ce E

nviro

nmen

t Hydraulic fracturing resulting in seismic activity due to the reactivation of geological faults or alteration of tectonic stresses

Opening of fractures within geological material in the surrounds of dormant geological faults, potentially resulting in fault reactivation.

Origin has a detailed understanding of the geological faults and stress fields (Section 2.2.2.3) within the project area, established using the following the techniques:

• Development of a mechanical earth model (see Section 2.4.3), incorporating Origin’s understanding of the local geological stress regime at each location to be hydraulically fractured. This understanding allows Origin to design hydraulic fracturing considerate of the local geological stress regime.

• Seismic surveys (to inform understanding of subsurface geometric relationships) .

• Widespread geological drilling programs (to inform subsurface stratigraphic understanding).

No No further assessment of risk is considered warranted, based on the risk mitigation measures in place.

• The project area is one of the least seismically active areas on the Australian continent (see Section 2.2.2.4).

• Geological faults within the area are considered to be dormant (see Section 2.2.2.2)

• Each hydraulic fracturing operation is designed, considerate of the local geological stress regime.

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Alteration of groundwater quality in aquifers overlying or underlying the target coal seams

Contamination of groundwater in aquifers overlying or underlying the target coal seam with either coal seam groundwater or hydraulic fracturing chemicals due to: • Hydraulic fracturing creating a hydraulic

connection between the target coal seam and overlying or underlying aquifers;

• Failure of the integrity of the CSG well, resulting in a connection forming between fluid inside the well and the aquifers overlying the target coal seam.

• Loss of hydraulic fracturing fluids into the over- or under-lying aquifers.

The coal seams targeted by Origin hydraulic fracturing operations are separated by low permeability aquitards, made of high strength, ductile (relative to coal) rock (see Section 2.2.3 and 2.4.3).

Hydraulic fracturing operations are designed so as not to propagate outside of the target coal seam, through part of this design is the establishment of a safe injection pressure operating envelope (see Section 2.4.4). This operating envelope is developed based on consideration of:

• CBL results

• Mechanical earth model (see Section 2.4.3)

• Stimulation models (see Section 2.4.3)

• Historical tracer results

• Relevant legislation

• Internal and external standards

No On the basis of the hydrogeological setting within the project area (Sections 2.2.3,2.2.4), and that APLNG adhere to the protocols which they have put in place regarding well integrity (Section 2.3) and hydraulic fracturing process control (Section 2.4.4), there is no complete exposure pathway between groundwater in the aquifers adjacent to the coal seam and hydraulic fracturing fluid or coal seam groundwater. Hence, no further assessment of this risk is warranted.

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Contamination of groundwater in the target coal seams, which is then accessed by landholder bores

Previous hydraulic fracturing pilot campaigns have demonstrated that not all hydraulic fracturing chemicals are recovered from the well (hence coal seam) during the flow-back period.

In locations where groundwater resources are limited, some landholders in the project area have installed water bores which source groundwater from the target coal seams (see Figure 24). Typically groundwater sourced from coal seams within the project area is suitable only for stock watering purposes, due to its high salinity (Section 2.2.5).

Based on the hydrogeological setting within the project area (Section 2.2.3), in order for the pathway to be valid in the context of exposure to hydraulic fracturing fluids, a groundwater supply bore would need to source groundwater from either:

1. Directly within the hydraulically fractured zone ofthe coal seam; or

2. Down hydraulic gradient of the hydraulicallyfractured zone, within the target coal seam.For example, if a landholder were in install a newbore, sufficiently close and down hydraulicgradient of a hydraulically fractured gas well andscreened in the target coal seam, then there is apotential exposure pathway for residual chemicalsto flow in groundwater and over time reach thelandholder bore and be brought to surface.

The second scenario assumes that following the hydraulic fracturing procedure, the coal seam is not depressurised by the CSG well.

APLNG have protocols in place which preclude hydraulic fracturing operations impacting landholder bores.

Scenario 1

Prior to commencing a hydraulic fracturing campaign, Origin performs Baseline Assessments of all groundwater bores within 1km of horizontal separation from a target well. Part of this assessment is to understand the precise location of bores and their likely source aquifer. If a landholder bore is potentially screened within the radius of influence of a hydraulic fracturing operation (both horizontally and vertically), that gas well is not hydraulically fractured. Hence Scenario 1 becomes invalid.

Scenario 2

Typically Origin commences depressurising the coal seam within weeks of the conclusion of the hydraulic fracturing operation. On the basis that depressurisation commences, Scenario 2 becomes invalid as any hydraulic fracturing chemicals remnant within the coal seam will flow towards the CSG well.

Yes Scenario 1 The protocols that Origin has in place to prevent hydraulic fracturing occurring near landholder bores screened in target coal seams, negate the requirement for further consideration of the risks of Scenario 1.

Scenario 2 Despite Origin typically commencing depressurisation of the coal seam within weeks of the hydraulic fracturing operation, the potential that this does not occur cannot be eliminated entirely. For example, Origin elects not to commence depressurisation of a pilot gas field following hydraulic fracturing, for operational reasons.

Hence an understanding of the potential for chemicals remaining in the coal seam to migrate in groundwater is achieved with a fate and transport assessment (see Section 3.5). The risk associated with leaving radiological tracers in hydraulically fractured zoned is performed in considered in Section 6.2 .

The understanding garnered from these assessments also informs whether the cumulative impact of residual chemicals sourced from multiple hydraulically fractured gas wells has the potential to increase the risk of Scenario 2.

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On the basis of the assessment presented above, the following presents a summary of the key issues that will be considered further:

1. Loss of containment of chemicals used for hydraulic fracturing, causing harm to workers, residents or the environment (to be assessed in Sections 3.4 to 5.0);

2. Harm to workers, residents or fauna due to noise or vibrations from hydraulic fracturing operations (to be assessed in Section 6.1)

3. Contamination of groundwater in the target coal seams that is accessed by landholder bores (to be assessed in Sections 3.5 and 6.2)

3.4 Identification of Contaminants of Potential Concern 3.4.1 Introduction

This section identifies the nature of chemicals used and recovered via operations at the site and considers their potential to represent contaminants of potential concern via:

• Their Persistence, Bioaccumulation and Toxicity (PBT assessment);

• Comparison of chemical concentrations with screening criteria for human health; and

• Comparison of chemical concentrations with screening criteria for environmental impacts.

3.4.2 Identification of Human Health COPC in Flowback Water

COPC have been identified as those which are known or suspected to be present at concentrations high enough to warrant inclusion in an assessment of human health risks. The identification of COPC is based on the assessment of the nature and extent of these chemicals in the environment on-site. Two datasets were evaluated in this HHRA: a theoretical and an empirical dataset.

3.4.2.1 Empirical Dataset

The empirical dataset was obtained from the laboratory analysis of flowback water from previous pilot operations collected in 2014. The determination of COPC from the empirical dataset was based on a comparison of the analytical results with human health-based screening level guidelines. It should be noted that the presence of chemicals at concentrations higher than the screening level guidelines does not indicate an unacceptable risk; rather, it indicates that potential exposures to these chemicals should be evaluated in greater detail, taking into account site-specific pathways of exposure. The screening criteria considered in this assessment include:

• Australian Drinking Water Guidelines (ADWG), 2016; The National Health and Medical Research Council (NHMRC) and the Agriculture and Resource Management Council of Australia and New Zealand have developed the Australian Drinking Water Guidelines, updated in 2016. The guidelines provide health-based and aesthetic values for a range of micro-organisms, physical quality, inorganic chemicals, organic chemicals, radiological quality and pesticides. The health-based guideline values, which were used to identify COPC in the groundwater, are concentrations, which, based on present knowledge, do not result in any significant risk to the health of a consumer of the water over a lifetime. These guidelines are recognised within the Amended ASC NEPM (Schedule B(1) Guideline on Investigation Levels for Soil and Groundwater, 2013) as relevant Groundwater Investigation Levels (GILs) for the assessment of human health issues at the point of extraction (for use as drinking water – protection of human health issues associated with use of water as domestic supply within households). These guidelines are more current and extensive than the ANZECC 2000 Guidelines for Recreational Water Quality and Aesthetics (relevant to lower levels of exposure than drinking water), and, hence, were used in preference to the recreational guidelines.

• World Health Organisation Drinking Water Guidelines (WHO DWG), 2008 and rolling revisions. The WHO has also developed drinking water guidelines using the same approach as in the

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ADWG. The health-based guideline values, which were used to identify COPCs in the groundwater, are concentrations, which, based on present knowledge, do not result in any significant risk to the health of a consumer of the water over a lifetime.

• USEPA Regional Screening Levels 2016. Where no guideline value was available from the above sources, the USEPA Regional Screening Levels (RSLs) were used. The RSLs are conservative, risk-based values for soil, tap water and air. It should be noted that the RSLs are currently not recognised in Australia. However, they were used in this assessment to provide a screening level for the purpose of identifying the COPC within soil (based on industrial soil SLs) and groundwater (based on tap water SLs) for further assessment.

Table 10 presents a summary of the flowback water data reviewed with a comparison against the relevant screening levels for determination of COPC requiring further assessment in this HHRA. Only chemicals above the LOR are assessed for screening purposes. Table 10 Identification of empirical COPC in flowback water on-site during operations

Analyte Detected in Flowback Water

Max Concentration Reported in 2014 (mg/L)*

Adopted Screening Level Guideline (mg/L) Selected as COPC?

Value Source

benzene 0.006 0.001 ADWG Yes

toluene 0.013 0.8 ADWG No

ethylbenzene 0.002 0.3 ADWG No

xylenes 0.0081 0.6 ADWG No

TRH C6-C10 0.5 15 WHO No

TRH C10-C16 0.05 0.1 WHO No

TRH C16+ 0.62 0.09 WHO Yes

aluminium 0.089 0.2 ADWG No

antimony 0.0013 0.003 ADWG No

arsenic 0.0022 0.01 ADWG No

barium 7.1 2 ADWG Yes

boron 2 4 ADWG No

cobalt 0.0014 4 ADWG No

copper 0.0044 2 USEPA No

iron 4.9 -- -- No

lead 0.00052 0.01 ADWG No

magnesium 14 -- -- No

manganese 0.093 0.5 ADWG No

mercury 0.0003 0.001 ADWG No

molybdenum 0.0025 0.05 ADWG No

nickel 0.0044 0.02 ADWG No

selenium 0.0036 0.01 ADWG No

vanadium 0.0005 0.086 USEPA No

zinc 0.0057 3 ADWG No

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Notes: *2014 data from previous pilot operations, sourced from Origin.-- No human health guideline availableADWG Australian Drinking Water Guidelines (NHMRC 2011) updated in 2016)WHO Guidelines for Drinking Water Quality (2011)USEPA Regional Screening Levels (2016)Shaded cells indicate COPEC assessed as part of this HHRA

Review of the data presented in Table 10 indicates that in relation to the assessment of risks to human health a number of the compounds detected are well below the adopted screening level criteria. These compounds will not significantly contribute to any risk issues evaluated at the site and will not be further evaluated in this assessment. Only those compounds detected in flowback water that exceed the available guidelines are considered further in this assessment.

3.4.2.2 Theoretical Dataset

The theoretical dataset calculated exposure point concentrations (EPCs) based on theoretical calculations of exposure using the mass balance data for each hydraulic fracturing fluid system (six fluid systems in total, 2 water and 4 gel). For the purpose of this assessment, it was assumed that between 20% and 60% of the mass of chemicals injected into the well will be present in the flowback water. The theoretical concentrations of the frac chemicals in flowback water are presented in Table 11 to Table 16 below. The determination of COPC from the theoretical dataset was based on a comparison of the estimated concentrations with human health-based screening level guidelines. Where available, the Australian Drinking Water Guidelines (ADWG 2016) (i.e. concentrations in water that are safe for all members of the population to consume every day for a lifetime) have been identified and considered in this assessment. Where these guidelines are not available and the available published reviews have identified a suitable Tolerable Daily Intake (TDI) or No Observed Adverse Effects Level (NOAEL) this value has been presented and used to derive a preliminary drinking water guideline following guidance provided by the National Health and Medical Research Council (refer to Section 4.4.2 for further discussion). Table 11 Theoretical concentrations of COPC in flowback water - fluid system

COPC Mass injection in stimulation fluid (mg/L)

Flowback Concentration Adopted Screening Level Guideline (mg/L)

Selected as COPC?

20% mass recovery (mg/L)


Water-based stimulation fluid system

Acetic acid 312 62 187 NA* (Based on pH: 6.5 to 8.5

No

Sodium hydroxide (caustic soda)

20 4 12 NA* (Based on pH: 6.5 to 8.5)

No

Sodium hypochlorite

163 33 98 NA* (Based on pH) No

Notes: D – Derived; A – ADWG 2016; NA – Not applicable, *refer to Table 24 for more detail; mg/L – milligram per litre

Table 12 Theoretical concentrations of COPC in flowback water - fluid system

COPC Mass Injected in Stimulation Fluid (mg/L)


Selected as COPC?

20% mass recovery

(mg/L)

60% mass recovery

(mg/L)

Water-based stimulation fluid system

2-methyl-2h-isothiazol- 3-one 1.1 0.2 0.7 0.078 (D) Yes

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COPC Mass Injected in Flowback Concentration Adopted Selected

(Methylisothiazolinone)

5-chloro-2-methyl-2h-isothiazolol-3-one (Methylchloroisothiazolinone)

3.5 0.7 2.1 0.078 (D) Yes

Acetic acid 291 58 175 NA* (Based on

pH: 6.5 to 8.5) No

Cristobalite 0.6 0.1 0.3 NA* No

Diatomaceous earth, calcined 33.4 6.7 20.0 NA* No

Magnesium nitrate 17.4 3.5 10.4 50 (A) No

Magnesium chloride 3.3 0.7 2.0 250 (as chloride,

A) No


Table 13 Theoretical concentrations of COPC in flowback water - fluid system



Selected as COPC?



Gel-based stimulation fluid

Acetic acid 518 104 311 NA* (Based on pH: 6.5 to 8.5)

No

Cellulase Enzyme/hemicelluase 22 4 13 2.3 (D) Yes

Citric Acid 345 69 207 4.7 (D) Yes

Coffee Extract 46 9 28 100 (D) No

Guar gum 1211 242 726 49 (D) Yes

Hydrochloric Acid 7831 1566 4699 NA* (Based on pH)

No

Lactose 482 96 289 4.0 (D) Yes

MEA borate 612 122 367 4.0 (D) Yes

Potassium chloride 19934 3987 11960 71 (D) Yes

Shellac, ammonium salt 101 20 61 2.0 (D) Yes

Sodium bisulfite 11 2 7 500 as sulfate (A)

No

Sodium hydroxide (caustic soda) 2 0.5 1 NA* (Based on pH: 6.5 to 8.5)

No

Sodium polyacrylate 47 9 28 12 (D) Yes

Talc, Magnesium Silicate 4 0.7 2 NA* No

Tributyl tetradecyl phosphonium chloride 66 13 39 NA* No

Notes: D – Derived; A – ADWG 2016; NA – Not applicable,* refer to Table 24 for more detail; mg/L – milligram per litre

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Table 14 Theoretical concentrations of COPC in flowback water – fluid system



Selected as COPC?




1-Propanaminium, 3-amino-n-(carboxymethyl)-n,n-dimethyl-n-coco alkyl

2851 570 1711 0.21 (D) Yes

Acetic acid 834 167 500 NA* (Based on pH:6.5 to 8.5)

No

Cellulase Enzyme 46 9 28 2.3 (D) Yes

Citric Acid 378 76 227 4.7 (D) Yes

Coffee Extract 78 16 47 100 (D) No

Glycerol 393 79 236 39 (D) Yes

Guar gum 3395 679 2037 49 (D) Yes


No

Lactose 602 120 361 4 (D) Yes

MEA borate 1050 210 630 4 (D) Yes

Potassium chloride 19856 3971 11914 71 (D) Yes

Shellac, ammonium salt 159 32 95 2.0 (D) Yes

Sodium bisulfite 13 3 8 500 as sulfate (A)

No

Sodium chloride 1375 275 825 NA* No

Sodium polyacrylate 65 13 39 12 (D) Yes

Talc, Magnesium Silicate 3 1 2 NA* No

Tributyl tetradecyl phosphonium chloride

121 24 73 NA* No

Sodium hydroxide (caustic soda) 2 0.4 1 NA* (Based on pH: 6.5 to 8.5)

No

Notes: D – Derived; A – ADWG 2016; NA – Not applicable,* refer to Table 24 for more detail; mg/L – milligram per litre

Table 15 Theoretical concentrations of COPC in flowback water – fluid system



Selected as COPC?




Aluminium Sulfate 660 132 396.2 0.18 (A) Yes

Maltodextrin 124 25 74.3 NA* No

Sodium Carboxymethyl Cellulose 5005 1001 3003.3 NA* No

Sodium Lauryl Sulfate 104 21 62.3 4.4 (D) Yes

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COPC Mass Injected Flowback Concentration Adopted Selected

Sorbitan, monododecanoate, poly(oxy-1,2-diethanediyl)

189 38 113.3 98 (D) Yes

Sulphuric Acid 165 33 98.9 NA* (Based on pH)

No

Hemicellulase Enzyme 1.0 0.2 0.6 2.3 (D) No

Notes: D – Derived; A – ADWG 2016; NA – Not applicable, refer to Table 24 for more detail; mg/L – milligram per litre

Table 16 Theoretical Concentrations of COPC in Flowback Water – System



Selected as COPC?




Gelatins 84 17 51 NA* No

Non-crystalline silica (impurity) 6 1 4 NA* No

Glutaraldehyde 156 31 94 0.016 (D) Yes

Glycerol 296 59 178 39 (D) Yes

Guar gum 2367 473 1420 49 (D) Yes

Potassium Hydroxide 336 67 202 NA* (Based on pH)

No

Cellulase Enzyme 118 24 71 2.3 (D) Yes

Diammonium peroxidisulphate 356 71 214 500 (A) No

Potassium borate 909 182 545 3.5 (A, as boron) Yes


No


3.4.3 Persistence, Bioaccumulation and Environmental Toxicity – Identification of Environmental COPCs

A requirement of the EA conditions is to undertake an environmental hazard assessment of the current and proposed fracturing chemicals. This semi qualitative assessment is an evaluation of the environmental hazard of the constituents of the hydraulic fracturing fluid based on their persistence (P), bioaccumulation (B) and toxicity (T). The PBT assessment has been conducted according to guidance developed by the Australian Government Department of Health National Industrial Chemicals Notification and Assessment Scheme (NICNAS). The criteria considered are presented in Table 17. Table 17 PBT criteria adopted by NICNAS

Criterion PBT criteria

P For PBT purposes a chemical is considered persistent in a particular media if its half-life in the media exceeds the following: Half-life (T1/2) >2 months in water Half-life (T1/2) >6 months in soil Half-life (T1/2) >6 months in sediment Half-life (T1/2) >2 days in air

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Criterion PBT criteria

B For PBT purposes a chemical is considered to be bioaccumulative if it has a BCF/BAF of >2000, or in its absence of any BCF/BAF measurement a log Kow >4.2.

T For PBT purposes, in respect of aquatic toxicity, a chemical may be considered toxic under the following circumstances (corresponding to criteria for GHS chronic category 1: Non-rapidly degradable substances for which there are adequate chronic toxicity data available

Chronic NOEC or ECx (for fish) <0.1 mg/L and/or

Chronic NOEC or ECx (for crustacea) <0.1 mg/L and/or

Chronic NOEC or ECx (for algae or other aquatic plants)

<0.1 mg/L

Rapidly degradable substances for which adequate chronic toxicity data are available

Chronic NOEC or ECx (for fish) <0.01 mg/L and/or

Chronic NOEC or ECx (for crustacea) <0.01 mg/L and/or

Chronic NOEC or ECx (for algae or other aquatic plants)

<0.01 mg/L

Substances for which adequate chronic toxicity data are not available (providing criteria for P and B are met)

96 h LC50 (for fish) <1 mg/L and/or

48 h EC50 (for crustacea) <1 mg/L and/or

72 or 96 ErC50 (for algae or other aquatic plants) <1 mg/L

And the substance is not rapidly degradable and/or the experimentally determined BCF is >500 (or, if absent, the log Kow is >4.2

Toxicity to other (terrestrial) organisms

Should be considered on a case by cases basis, compared with the highly toxic classifications DotE has developed for ag/vet chemicals

Long term toxicity or evidence such as endocrine disruption effects

Should be considered on a case-by-case basis.

The screening criteria developed by the EU for REACH (ECHA, 2008) can also be used as surrogate information to decide whether a substance may potentially fulfil the PBT criteria. A summary of these screening criteria is provided in Table 18. Table 18 EU REACH screening criteria for persistent (P), very persistent (vP), bio-accumulative (B), very bio-

accumulative (vB) and toxicity (T)

Type of Data Criterion Screening Assignment

Persistence Ready biodegradability test Readily biodegradable Not P and not vP

Enhanced ready biodegradability test Readily biodegradable Not P and not vP

Specified tests on inherent biodegradability

Zahn-Wellens (OECD 302B) >70% mineralization (DOC removal) within 7 days; log phase no longer than 3 days; removal before degradation occurs below 15%; no pre-adapted inoculum

Not P

MITI II test (OECD 302C) >70% mineralization (O2 uptake) within 14 days; log phase no longer than 3 days; no pre-adapted inoculum

Not P

Biowin 2 (non-linear model prediction) and Biowin 3 (ultimate biodegradation time)

Does not biodegrade fast (probability) and ultimate biodegradation timeframe prediction: >months (value <2.2)

P

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Type of Data Criterion Screening Assignment

or

Or

Biowin 6 (MITI non-linear model prediction) and Biowin 3 (Ultimate biodegradation time)

Does not biodegrade fast (probability <0.5) and ultimate biodegradation timeframe prediction: >months (value <2.2)

P

Bioaccumulation Convincing evidence that a substance can biomagnify in the food chain (e.g., field data).

e.g., BMF >1 B or vB, definitive assignment possible

Octanol-water partition coefficient (experimentally derived or estimated by valid QSAR)

Log Kow < 4.5 Not B and not vB

Toxicity

Short-term toxicity aquatic toxicity (algae, daphnia, fish)

EC50 or LC50 <0.01 mg/L T, criterion considered to be definitely fulfilled

Short-term toxicity aquatic toxicity (algae, daphnia, fish)

EC50 or LC50 <0.1 mg/L T

Avian toxicity (subchronic or chronic toxicity or toxic for reproduction)

NOEC <30 mg/kilogram(kg) food T

On the basis of this approach, the chemicals proposed to be used in hydraulic fracturing fluids have been evaluated, with the outcomes of the assessment conducted summarised in Table 19 and in individual toxicity profiles in Appendix C.

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Table 19 PBT Assessment of the Hydraulic Fracturing Chemicals Used in the Project Area

Substance P/vP Criteria Fulfilled B/vB Criteria Fulfilled T Criteria Fulfilled? Overall Conclusion

Acetic acid No. The acetate ion of acetic acid is readily biodegradable and thus it does not meet the screening criteria for persistence.

No. The log Kow for acetic acid is -0.17. Acetate is also found in the body and is metabolized as part of the body’s biochemical pathways. Thus, acetic acid (specifically, the acetate ion) does not meet the screening criteria for bioaccumulation.

No. The NOECs from the chronic aquatic toxicity data on acetic acid are >0.01 mg/L, hence does not meet the screening criteria for toxicity. Not PBT

Aluminium sulfate No. Not applicable, inorganic salt. Biodegradation is not applicable to aluminium sulfate.

No. Aluminium sulfate is not expected to bioaccumulate.

No. The chronic NOEC value in fish for aluminium is <0.1 mg/L; thus, the dissolved aluminium from aluminium sulfate meets the screening criteria for toxicity

Not PBT

Calcium chloride No. Not applicable, inorganic salt, ionic species ubiquitous in environment.

No. Not applicable, inorganic salt, ionic species ubiquitous in environment.

No chronic toxicity data exist on calcium chloride; however, the acute EC (L) 50s are >0.1 mg/L in fish, invertebrates and algae. Thus, calcium chloride does not meet the screening criteria for toxicity.

Not PBT

Cellulase and hemicelluase enzyme

No. Celluase is readily biodegradable and thus does not meet the screening criteria for persistence.

No. Cellulase has a high molecular weight (20 to 80 kD), has hydrophilic properties (high water solubility, log Kow <0), and is readily metabolized in organisms. Thus, it does not meet the screening criteria for bioaccumulation.

No chronic toxicity data exist; The acute EC(L)50 of cellulase is >0.1 mg/L in fish, invertebrates and algae. Thus, it does not meet the screening criteria for toxicity.

Not PBT

Cocamidopropyl betaine (CAPB)

No. CAPB is readily biodegradable and does not meet the screening criteria for persistence.

No. Estimated Kow values do not meet the screening criteria for bioaccumulation.

No. The lowest chronic NOEC for CAPB is >0.01 mg/L and hence does not meet the screening criteria for toxicity.

Not PBT

Cristobite, silica and diatomaceous earth

No. Not applicable, inorganic substance, ubiquitous in environment.


No. Long term data not available (acute data >0.1 mg/L).

Not PBT

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Diammonium peroxidisulphate



No chronic toxicity data exist; however, the acute EC(L)50s are >0.1 mg/L in fish, invertebrates and algae. Thus does not meet the screening criteria for toxicity.

Not PBT

Guar gum No biodegradation information was found on guar gum. However, guar gum is a naturally occurring polysaccharide which would be expected to readily biodegrade. Thus, it is not expected to meet the screening criteria for persistence

The molecular weight of guar gum is high ranging from 200,000 to 300,000 daltons, and it is also water soluble. Thus, guar gum is not expected to meet the criteria for bioaccumulation

The acute aquatic toxicity of guar gum is >0.1 mg/L. Thus, guar gum is not expected to meet the screening criteria for toxicity

Not PBT

Hydrochloric acid No. Hydrochloric acid is an organic salt that dissociates completely to hydrogen and chloride ions in aqueous solutions. Biodegradation is not applicable to these inorganic ions; both hydrogen and chloride ions are also ubiquitous and are present in most water, soil and sediment. Thus, the persistent criteria is not considered applicable to this inorganic salt.

Hydrogen and chloride ions are essential to all living organisms and their intracellular and extracellular concentrations are actively regulated. Thus, hydrochloric acid is not expected to bioaccumulate.

No chronic toxicity data exist on hydrochloric acid; however, the acute EC(L)50s are >0.1 mg/L in fish, invertebrates and algae. Thus, hydrochloric acid does not meet the screening criteria for toxicity.

Not PBT

Lactose No. No experimental biodegradation data are available on lactose. QSAR model predict lactose to be readily biodegradable and thus, lactose does not meet the screening criteria for persistence.

No. The estimated log Kow and BCF does not meet the screening criteria for bioaccumulation.

The estimated acute EC(L)50 values of lactose indicate that it is non-toxic to fish, invertebrates and algae. Thus, it does not meet the screening criteria for toxicity.

Not PBT

Magnesium chloride Magnesium chloride is an organic salt that dissociates completely to magnesium and chloride ions in aqueous solutions. Biodegradation is not applicable to these inorganic ions; both magnesium and chloride ions are also ubiquitous and are present in most water, soil and sediment. Thus, the persistent criterion is not considered applicable to this inorganic salt.

Magnesium and chloride ions are essential to all living organisms and their intracellular and extracellular concentrations are actively regulated. Thus, magnesium chloride is not expected to bioaccumulate.

No chronic toxicity data exist on magnesium chloride; however, the acute EC(L)50s are >0.1 mg/L in fish, invertebrates and algae. Thus, magnesium chloride does not meet the adopted screening criteria for toxicity.

Not PBT

Magnesium nitrate Magnesium nitrate is an organic salt that dissociates completely to magnesium and nitrate ions in aqueous

Magnesium ions are essential to all living organisms and its intracellular and

No chronic toxicity data exist on magnesium nitrate; however, the acute

Not PBT

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solutions. Biodegradation is not applicable to these inorganic ions; both magnesium and nitrate ions are also ubiquitous and are present in most water, soil and sediment. Thus, the persistent criterion is not considered applicable to this inorganic salt

extracellular concentrations are actively regulated. Nitrates are ions that are very soluble in aqueous solutions. Thus, magnesium nitrate is not expected to bioaccumulate.

EC(L)50s are >0.1 mg/L in fish, invertebrates and algae. Thus, magnesium nitrate does not meet the screening criteria for toxicity.

Maltodextrin Maltodextrin is expected to be readily biodegradable and thus would not be expected to meet the screening criteria for persistence.

The molecular weights of maltodextrin can be <1,000 and bioavailable to aquatic organisms. Maltodextrin is water-soluble and composed of D-glucose monomeric units; which are naturally occurring in aquatic organisms Thus, maltodextrin is not likely to meet the screening criteria for bioaccumulation.

No aquatic toxicity data could be found on maltodextrin. However, D-glucose, the monomeric units of maltodextrin, is found naturally in aquatic organisms. Thus, maltodextrin is not expected to meet the screening criteria for toxicity.

Not PBT

Methylisothiazolinone (MIT) and Methylchloroisothiazolinone (CMIT)

No. The half-lives of CMIT and MIT in a river water-sediment system were 17.3 hours and 9.1 hours, respectively. Thus, CMIT/MIT do not meet the criteria for persistence

No. The experimental BCF for CMIT is 67-114 in bluefish sunfish, and the BCF for MIT was determined to be 2.3. Thus, CMIT/MIT do not meet the criteria for bioaccumulation.

No chronic toxicity data are available for CMIT/MIT; however, the acute E(L)C50 values for algae are <0.1 mg/L. Thus, CMIT/MIT meet the screening criteria for toxicity.

Not P or B. Potentially T.

Monoethanolamine borate Monoethanolamine borate is readily biodegradable and thus it does not meet the screening criteria for persistence.

Inadequate data for determination of bioaccumulation for Monoethanolamine borate. However, the borate salt of monoethanolamine would not be expected to meet the screening criteria for bioaccumulation.

No chronic aquatic toxicity studies are available for monoethanolamine borate. The acute toxicity studies in fish, invertebrates and algae are >0.01 mg/L. Thus, monoethanolamine borate does not meet the criteria for toxicity.

Not PBT

Non crystalline silica No. Not applicable, inorganic substance, ubiquitous in environment.


No. Chronic toxicity data not available. Acute data >0.1 mg/L in fish, invertebrates and algae, hence does not meet the screening criteria for toxicity.

Not PBT

Potassium chloride Potassium chloride is an organic salt that dissociates Potassium and chloride ions are essential No chronic toxicity data exist on potassium Not PBT

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completely to potassium and chloride ions in aqueous solutions. Biodegradation is not applicable to these inorganic ions; both potassium and chloride ions are also ubiquitous and are present in most water, soil and sediment. For the purposes of this PBT assessment, the persistent criteria is not considered applicable to this inorganic salt.

to all living organisms. Thus, potassium chloride is not expected to bioaccumulate.

chloride; however, the acute EC(L)50s are >0.1 mg/L in fish, invertebrates and algae. Thus, potassium chloride does not meet the screening criteria for toxicity

Shellac Shellac, ammonium salt is a natural resin and is not expected to readily biodegradable. Thus, it meets the screening criteria for persistence

Shellac, ammonium salt has a high molecular weight (~2,000) and is insoluble in water at environmentally relevant pHs. It is not expected to be bioavailable and thus, it does not meet the screening criteria for bioaccumulation.

There are no aquatic toxicity in which to evaluate the aquatic toxicity of shellac, ammonium salt. It has, however, a high molecular weight (~2,000) and is also insoluble in water at environmentally relevant pHs; it is not expected to be bioavailable. Thus, shellac, ammonium salt is not expected to meet the screening criteria for toxicity.

Not PBT

Sodium carbonate No. Inorganic salt, biodegradation not applicable. No. Inorganic salt, bioaccumulation not applicable.

No chronic toxicity data exist; however, the acute EC(L)50s are >0.1 mg/L. Thus, does not meet the screening criteria for toxicity

Not PBT

Sodium carboxymethyl cellulose

Sodium carboxymethyl cellulose is a water-soluble semisynthetic polymer and is not readily biodegradable. Thus, it meets the screening criteria for persistence.

Sodium carboxymethyl cellulose is a water-soluble semisynthetic polymer and is expected to have a molecular weight of >1,000 which limits its bioavailability to aquatic organisms. Thus, it is not expected to bioaccumulate.

The acute EC(L)50 of sodium carboxymethylcellulose is >0.1 mg/L in fish, invertebrates and algae. Thus, it does not meet the screening criteria for toxicity

Not PBT

Sodium chloride Sodium chloride is an organic salt that dissociates completely to sodium and chloride ions in aqueous solutions. Biodegradation is not applicable to these inorganic ions; both sodium and chloride ions are also ubiquitous and are present in most water, soil and

Sodium and chloride ions are essential to all living organisms and their intracellular and extracellular concentrations are actively regulated. Thus, sodium chloride is not expected to bioaccumulate.

No chronic toxicity data exist on sodium chloride; the acute EC(L)50s are expected to be >0.1 mg/L in fish, invertebrates and algae based on aquatic toxicity studies involving sodium and chloride ions. Thus,

Not PBT

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sediment. The persistent criteria is not considered applicable to this inorganic salt.

sodium chloride does not meet the screening criteria for toxicity.

Sodium hydroxide Not applicable (inorganic salt, ionic species ubiquitous in environment)

Not applicable. Biodegradation is not applicable to these inorganic ions; sodium and hydroxide ions are ubiquitous and are present in most water, soil and sediment.

Not applicable. Chronic toxicity data not available (acute data >0.1 mg/L in fish, invertebrates and algae), thus sodium hydroxide does not meet the screening criteria for toxicity.

Not PBT

Sodium hypochlorite Not applicable (inorganic salt, ionic species ubiquitous in environment)

Not applicable (inorganic salt, ionic species ubiquitous in environment)

Not applicable. Chronic toxicity data not available (acute data <0.1 mg/L), thus sodium hydroxide is potentially toxic.

Not P or B. Potentially T.

Sodium lauryl sulfate Sodium lauryl sulfate is readily biodegradable and thus does not meet the screening criteria for persistence

The experimental BCFs in freshwater fish are in the range of 1.5 to 5.3. Thus, sodium lauryl sulfate does not meet the criteria for bioaccumulation.

The lowest NOEC from a chronic invertebrate toxicity study is 0.88 mg/L. This value is >0.01 mg/L; thus, sodium lauryl sulfate does not meet the screening criteria for toxicity.

Not PBT

Sodium thiosulfate Not applicable (inorganic salt, ionic species ubiquitous in environment)

Not applicable. Biodegradation is not applicable to these inorganic ions; sodium and sulfate ions are ubiquitous and are present in most water, soil and sediment.

Not applicable. Chronic toxicity data not available (acute data >0.1 mg/L in fish, invertebrates and algae).

Not PBT

Sorbitan QSAR model predicts sorbitan to biodegrade and to be recalcitrant. Thus, sorbitan meets the screening criteria for persistence

Using QSAR modelling, the estimated log Kow and BCF is not expected to meet the screening criteria for bioaccumulation.

There are no toxicity data on sorbitan; nor are there any chronic toxicity data. The acute algal EC50 value for Polysorbate 80 (surrogate) is >0.1 mg/L. Thus, sorbitan is not expected to meet the screening criteria for toxicity.

Not PBT

Sulphuric acid Sulphuric acid is an organic salt that dissociates completely to hydrogen and sulfate ions in aqueous solutions. Biodegradation is not applicable to these inorganic ions; both hydrogen and sulfate ions are also

Hydrogen and sulfate ions are essential to all living organisms. Thus, Sulphuric acid is not expected to bioaccumulate.

Chronic toxicity studies have been conducted on Sulphuric acid. The lowest NOEC was reported to be 0.13 mg/L in fish; thus sulphuric acid does not meet the

Not PBT

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ubiquitous and are present in most water, soil and sediment. For the purposes of this PBT assessment, the persistent criteria is not considered applicable to this inorganic salt.

screening criteria for toxicity.

Talc Talc does not biodegrade in the environment. It is a naturally-occurring mineral and is persistent in the environment. However, for the purposes of this PBT assessment, it does not meet the criteria for persistence

Talc is not expected to be bioavailable to aquatic organisms; thus, it is does not meet the criteria for bioaccumulation

Talc is not expected to be bioavailable to aquatic organisms; thus, it is does not meet the criteria for toxicity. Not PBT

Tributyl tetradecyl phosphonium chloride (TTPC)

No information is available on persistence. No information is available on bioaccumulation.

No chronic toxicity data are available for TTPC. The lowest acute EC(L)50 of TTPC is 0.025 mg/L in invertebrates. Since this value is <0.1 mg/L, TTPC does meet the screening criteria for toxicity.

Inconclusive. Potentially T.

Coffee Caffeine is expected to be readily biodegradable and thus would not be expected to meet the screening criteria for persistence.

Caffeine is water-soluble and bioaccumulation is not expected according to the log Kow (0.091). Thus, caffeine is not likely to meet the screening criteria for bioaccumulation.

Long term data not available (acute data >0.1 mg/L); Thus, does not meet the screening criteria for toxicity. Not PBT

Citric acid

Citric acid is expected to be readily biodegradable and does not persist in the environment

Based on the low Log Kow and widespread natural occurrence, citric acid is not expected to have potential for bioaccumulation.

Long term data not available (acute data >0.1 mg/L); Thus, does not meet the screening criteria for toxicity.

Not PBT

Gelatins

No biodegradation information was found on gelatin. However, gelatin is a protein which would be expected to readily biodegrade. Thus, it is not expected to meet the screening criteria for persistence

The molecular weight of gelatin is variable, ranging from 10,000 to several hundred thousand daltons, and it is also water soluble. Thus, gelatin is not expected to meet the criteria for bioaccumulation

No toxicity information was found on gelatin. However as gelatin is derived from collagen, which is the principal constituent of connective tissues and bones of animals. Thus gelatin is not expected to meet the screening criteria for

Not PBT

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toxicity.

Glutaraldehyde

Glutaraldehyde is considered to be readily biodegradable and as such not persistent in the environment.

Based on the measured log Kow of 4.5, Glutaraldehyde is not bioaccumulative.

The acute aquatic toxicity of glutaraldehyde is > 0.01 mg/L. Hence the substance does not fulfill the screening criteria for toxicity.

Not PBT

Potassium hydroxide

Not applicable (ionic species ubiquitous in environment)

Not applicable (ionic species ubiquitous in environment)

No chronic toxicity data exist on potassium hydroxide; however, the acute EC(L)50s are >0.1 mg/L in fish, invertebrates and algae. Thus, potassium hydroxide does not meet the screening criteria for toxicity.

Not PBT

Sodium bicarbonate

Sodium bicarbonate is an inorganic salt that is present in the environment as sodium and bicarbonate ions. Biodegradation is not applicable to these inorganic ions. Thus, the persistent criterion is not considered applicable to this inorganic salt.

Sodium and bicarbonate ions are essential to all living organisms and its extracellular concentrations are actively regulated. Thus, sodium bicarbonate is not expected to bioaccumulate.

No chronic toxicity data exist on sodium bicarbonate; however, the acute EC(L)50s are >0.1 mg/L in fish, invertebrates and algae. Thus, sodium bicarbonate does not meet the screening criteria for toxicity.

Not PBT

Glycerol

The substance is demonstrated to be readily biodegradable. Thus, it is not expected to meet the screening criteria for persistence

Based on the measured log Kow of -1.75, Glycerol is not expected to bioaccumulate.

The acute EC(L)50s are >0.1 mg/L in fish, invertebrates and algae. Thus, potassium hydroxide does not meet the screening criteria for toxicity.

Not PBT

Sodium bisulfite

Sodium bisulfite is an organic salt that dissociates completely to sodium and sulfite ions in aqueous solutions. Sulfite is also naturally present in the environment, formed from the release of sulfur dioxide by natural and anthropogenic sources. Sulfite is rapidly oxidized to sulfate in water. Biodegradation is not applicable to these inorganic ions; sodium and sulfate ions are also ubiquitous and are present in most water, soil and sediment. For the purposes of this PBT assessment, the persistent criteria is not considered

The sulfite ion is rapidly oxidized to sulfate in water. Both sodium and sulfate ions are essential to all living organisms and their intracellular and extracellular concentrations are actively regulated. Thus, sodium sulfite is not expected to bioaccumulate.

No chronic toxicity data exist on sodium bisulfite; however, the acute EC(L)50s are >0.1 mg/L in fish, invertebrates and algae. Thus, sodium bisulfite does not meet the screening criteria for toxicity. Not PBT

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applicable to this inorganic salt.

Sodium polyacrylate

Sodium polyacrylate has limited biodegradation potential and thus meets the screening criteria for persistence.

Bioaccumulation of sodium polyacrylate is unlikely due to the high molecular weight of the polymer

The acute EC(L)50s are >0.1 mg/L in fish, invertebrates and algae. Thus, sodium polyacrylate does not meet the screening criteria for toxicity.

Potentially persistent

Potassium borate

For the purposes of this PBT assessment, the persistent criteria is not considered applicable to this inorganic substance.

For the purposes of this PBT assessment, the bioaccumulation criteria is not considered applicable to this inorganic substance.

For the purposes of this PBT assessment, the toxicity criteria is not considered applicable to this inorganic substance.

Not PBT

For chemical and physical properties not readily available from MSDS or the Hazardous Substances Databank (HSDB), modelled data was obtained from USEPA (2009) EPISUITETM.

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As the Table 19 above indicates, all of the compounds (with the exception of sodium polyacrylate, CMIT, MIT sodium hypochlorite and TTPC) utilised in hydraulic fracturing fluids are not considered to be persistent, bioaccumulative and toxic in the environment. As such, the compounds are expected to degrade in the sub-surface and would not be expected to remain in flow back water extracted from the well. Where these compounds are present in flow back water, they will readily degrade or dissociate in the environment and will not bioaccumulate in terrestrial or aquatic species. Sodium polyacrylate has limited biodegradation potential; however it is not bioaccumulative and is essentially non-toxic to aquatic species. While sodium hypochlorite, MIT and CMIT meets the screening criteria for toxicity, qualified by their acute toxicity capacity, adverse chronic outcomes are not evident based on their reactivity and lack of persistence and bioaccumulation in the environment. Limited information is available for TTPC (i.e no persistence or biodegradation information), however the acute toxicological data available suggests that TTPC does meet the screening criteria for toxicity. Primary adverse health effects associated with the use of TTPC (as a pure substance) are related to irritant and corrosive properties for the skin, eyes, nose and lungs. It is to be noted that Worker exposures of TTPC are addressed through the implementation of appropriate occupational health and safety procedures and management plans. Considering the significant dilution, sorption and biodegradation processes that occur in the coal seam, it is not expected that such properties of TTPC would be realised in the flowback water. A quantitative evaluation of the environmental risk posed by the COPCs above is presented in Section 5.0.

It is to be noted that some constituents used in hydraulic fracturing fluid, such as sand, are solids that once injected into the well are used to prop open fractures in the coal seam. These constituents are not sufficiently mobile such that they are extracted in flow back water. Hence the presence of these constituents in hydraulic fracturing fluid does not warrant any further evaluation in this risk assessment.

3.5 Residual Chemical Fate and Transport Modelling As part of the risk identification process (see Section 3.4.2), the Chemicals of Potential Concern (COPC) were identified amongst the chemicals used by APLNG for hydraulic fracturing. Chemicals which were deemed to be of potential concern are those known or suspected to be present at concentrations and quantities high enough to warrant inclusion in an assessment of risks to human health. The identification of COPC is based on the assessment of the nature, magnitude and extent of these chemicals in the environment on-site.

The potential of the COPC to migrate has been considered below, based on a conservative scenario informed by the site conceptual model.

3.5.1 Environmental Fate of Inorganic COPC

When hydrated, inorganic COPC either rapidly dissociate into salts or have restricted mobility based on their physical properties hydrated (i.e.: they are the consistency of a gel). On this basis, the migration of inorganic hydraulic fracturing chemicals is likely to result in a change in the alkalinity and/or salinity of groundwater within the immediate vicinity of the hydraulically fractured zone. As the quality of the groundwater within the receiving coal seam is already high salinity (see Section 2.2.4.3), a localised change in the alkalinity and salinity from dissociated inorganic COPC is considered a low risk in an aquifer environment and thus did not warrant further assessment using modelling.

3.5.2 Fate and Transport Modelling of Organic COPC

3.5.2.1 Methodology

A one-dimensional fate and transport model, BIOSCREEN-AT version 1.45 (S.S. Papadopulous & Associates Inc., 2014), was used to assess the potential extent of migration of the organic COPC in groundwater. This model uses the Domenico analytical solute transport model for solute transport in three-dimensional porous media. The Domenico model has the ability to simulate advection, dispersion and adsorption. For a given input concentration, the model calculates the maximum concentration at a given distance down the centreline of the contaminant plume.

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3.5.2.2 Modelled Scenario

The model considered the scenario in which a single CSG well is hydraulically fractured then ‘shut-in’ and never used for gas (or groundwater) extraction; in this instance, dewatering of the coal seam in the surrounds of the well is not performed following the hydraulic fracturing procedure.

The potential exposure pathway is for residual chemicals to migrate through the coal seam, beyond the fractured zone around the well, then into either water bores or artesian (discharge) springs which source groundwater from the target coal seam.

Should a regime of groundwater abstraction from the CSG well be implemented following the hydraulic fracturing procedure (as is typically the case), this scenario becomes invalid as any hydraulic fracturing chemicals residual within the coal seam will, over time, flow towards the CSG well, not away from the well towards the potential exposure pathways in the scenario.

3.5.2.3 Modelling Assumptions and Conservatism

The contaminant source in the modelled scenario was hydraulic fracturing chemicals residual in the coal seam following the hydraulic fracturing of a single CSG well, it was assumed that:

• Fractures formed by the hydraulic fracturing procedure propagate 200 metres from the well in the same direction as the regional hydraulic gradient (the most conservative direction of fracture propagation for the model).

• The contaminant source was infinite (conservative assumption), at a concentration of 100% of the concentration that is injected during the hydraulic fracturing process. This assumes the well is not flowed back at all following the hydraulic fracturing procedure.

• The well is not tied-in to a network of water pipelines or a ring tank after the hydraulic fracturing operation is concluded. This is conservative as depressurisation of CSG wells typically commences within weeks of completion of hydraulic fracturing.

• As the well is not flowed back, depressurisation of the coal seam from the CSG well is not initiated following the hydraulic fracturing operation, and the local groundwater flow regime is re-established immediately following the injection of the hydraulic fracturing fluids.

• Dispersion and sorption were the only processes simulated by the model (i.e.: biodegradation of the contaminants was not considered), a conservative approach for the model.

3.5.2.4 Adsorption Input Parameters

Fraction of Organic Carbon

The principal factor contributing to the sorption (hence migration retardation) of dissolved organic compounds is the organic carbon content of the aquifer (in this case, the coal seam). The greater the concentration of organic carbon in the aquifer, the greater sorption potential for organic chemicals, hence reduced potential for migration.

A study by Scott et al. (2007) reported that the carbon content of coal within the Walloon Coal Measures was in the range of 50-70%, with the balance comprised of ash. In the mudstone and siltstone layers which are typically interbedded with the coal seams, the organic carbon content is likely to be significantly less. Both the Australian CRC CARE Guidelines (CRC CARE 2011) and the New Zealand Ministry for the Environment Guidelines (NZ MfE, 2011) recommend the use of a value of 0.3% organic carbon in silt material, when field data is not available.

The organic carbon content of the coal rather than silt was used, given the formation permeability value used for modelling fluid movement was that of coal, not silt.

Organic Carbon-Water Partitioning Coefficient (Koc)

The organic carbon-water partitioning coefficient is a measure of the affinity of a chemical to adsorb to organic matter within the aquifer. Higher values of Koc represent less soluble chemicals, which adsorb the organic matter within the aquifer more readily.

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Modelled COPC

The organic COPCs were modelled were selected to incorporate chemicals from hydraulic fracturing fluid systems which will or have been used. Further, an effort was made to select COPCs with a range of solubilities, prioritising those that failed the PBT assessment.

The following COPCs were modelled:

• Cocamidopropyl betaine (1-Propanaminium, 3-amino-n-(carboxy methyl)-n,n-dimethyl-n-coco alkyl), 2281 mg/L left in coal seam, assuming only 20% chemical flowback from fluid system: (used at well Ramyard 23)

• Methylisothiazolinone (2-methyl-2h-isothiazol-3-one methylisothiazolinone or MIT), 1 mg/L left in coal seam, assuming only 20% chemical flowback from fluid system:

(to be used for Varidel and WAP campaigns)

• Methylchloroisothiazolinone (5-chloro-2-methyl-2h-isothiazolol-3-one), 4 mg/L left in coal seam, assuming only 20% chemical flowback from fluid system: (to be used for Varidel and WAP campaigns)

The input parameter selection process is summarised in Table 20. Table 20 Input Parameters for Fate and Transport Model

Parameters Input Value

Comment

Hydraulic Parameters Hydraulic Conductivity (m/day) 0.005 Based on the median hydraulic conductivity for the Walloon Coal

Measures (see Section 2.2.3.3), significantly higher (i.e. more conservative) than the interburden material.

Hydraulic Gradient(units) 0.004 Estimated from the Walloon Coal Measures potentiometric surface

Effective Porosity (%) 3 Estimated for natural fractures and cleats in the non-hydraulically fractured coal seam

Contaminant Plume Estimated Plume Length (m) 200 Estimated propagation of hydraulic fracture is 200 m from CSG well

Initial Longitudinal Dispersivity (m) 20 1/10 of the plume length; model default value

Initial Transverse Dispersivity (m) 2 1/10 of longitudinal dispersivity; model default value

Initial Vertical Dispersivity (m) 1 1/20 of longitudinal dispersivity; model default value

Modelled Contaminant Migration Area

Length (m) 100 -

Width (m) 100 -

Simulation time (years) 1000 -

Coal seam bulk density (rho) (kg/L) 1.5 Mean value for bituminous coal (Scott et al, 2007).

Fraction Organic Carbon 0.5 Scott et al. (2007) reported that the carbon content of coal within the Walloon Coal Measures was in the range of 50-70%, select the more conservative, 50%.

Modelled chemical

Thickness in Saturated Zone (m) 30 Coal thickness in the project area is typically 10% of total thickness of the surrounding formation (i.e. total thickness of coal ~ 30 m in 300 m thick Walloon Coal Measures)

Width (m) 10 -

http://en.wikipedia.org/wiki/5-chloro-2-methyl-4-isothiazolin-3-one

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Parameters Input Value

Comment

Concentration (mg/L)

Methylisothiazolinone 2-methyl isothiazolone (CAS: 2682-20-4)

1

(used at well Ramyard 23)

Concentration of chemical left in coal seam assuming only 20% of hydraulic fracturing fluid is recovered during well flowback (conservative). Concentration calculated from mass fraction information provided by contractor.

Methylchloroisothiazolinone 5-chloro-2-methyl-2h-isothiazolol-3-one(CAS: 26172-55-4)

5


Cocamidopropyl betaine 1-Propanaminium, 3-amino-n-(carboxymethyl)-n,n-dimethyl-n-coco alkyl (CAS: 61789-40-0)

2281


Soil Partition Coefficient (kg/L) Koc Solubility

Cocamidopropyl betaine 1-Propanaminium, 3-amino-n-(carboxymethyl)-n,n-dimethyl-n-coco alkyl (CAS: 61789-40-0)

647.5 Least

Koc values estimated using Episuite v.4.0 USEPA


19.38 Median


12.08 Most

3.5.2.5 Results

The modelling provided the migration distance of the contaminant plume for 5, 20, 100 and 1000 years after the hydraulic stimulation of the well, summarised in Table 21.

After 1000 years, the model simulated both the most and median solubility COPCs migrated 9 m from the leading edge of the fractured zone. Table 21 Results of fate and transport modelled simulations

Migration distance of contaminant (Attenuation distance for concentration to return to <LOR)

Modelled Contaminant 5 years 20 years 100 years 1000 years

Cocamidopropyl betaine 1-Propanaminium, 3-amino-n-(carboxy methyl)-n,n-dimethyl-n-coco alkyl (CAS: 61789-40-0)

1 m 1 m 1.5 m 6 m


1.5 m 2 m 3 m 7 m


1 m 2 m 4 m 9 m

LOR: Limit of Reporting; LOR = 0.001 mg/L in the model used to perform the simulation.




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4.0 Quantitative Human Health Risk Assessment

4.1 Exposure Assessment This section identifies the human populations (receptors) who may be exposed to the COPC identified for the site, and outlines the mechanisms (exposure pathways) by which these populations may be exposed. The exposure assessment also provides a quantitative estimate of exposure and intake of the COPC.

The assessment of exposure involves the evaluation of the data collected from the site, details associated with the site use and surrounding land uses, the nature of the impact identified and the potential for the impact to migrate off-site. An exposure pathway is a mechanism by which an individual or group of individuals (receptors) may be exposed to the COPC through mechanisms such as direct contact (which includes ingestion and dermal contact) and inhalation.

For an exposure pathway to be considered to be complete there must be all of the following:

• Source of COPC - how the chemical got into the environment;

• A transport media - how the chemical moves or migrates through the environment (soil, water or air);

• An exposure point - how people can come into contact with the chemicals (e.g. swimming, gardening, inhalation, direct contact or via the food web); and

• An exposure route - how the chemical could enter the body (e.g. inhalation, ingestion or dermal contact).

If any one of these steps (source, transport media, exposure point or route) is not present, then the exposure pathway is incomplete and, hence, further assessment of risks is not required.

In the cases where the exposure pathways are complete, or have the potential to be complete, then the pathways can be considered significant or less significant. The significance of the exposure pathway depends on the nature of the impact present, and the evaluation of the likely exposure concentrations that may be associated with the pathway.

4.2 Potential Exposure Pathways and Receptors Taking into account of the surrounding areas of the site, the scope of the risk assessment, the current nature and extent of impacts identified in groundwater, the potential receptors and pathways (significant and less significant) have been identified. In reviewing and considering the potential significance of exposure pathways, the following points have been considered:

• No further assessment is considered warranted for groundwater as there are no potentially complete exposure pathways. Detailed operational procedures have been provided that are designed to contain the hydraulic fracturing fluids within the coal sequences, and no connection exists between groundwater in the coal seams and surface-water, aquifers utilised for the purpose of extraction (for any beneficial use), or springs;

• Potential risks to workers involved with the hydraulic fracturing process, where the COPC are handled on and off-site (i.e. during transportation of the COPC to the site), have not been considered as detailed Health and Safety (H&S) procedures are employed to manage these exposures;

• It is noted that none of the COPC (with the exception of sodium polyacrylate, CMIT, MIT sodium hypochlorite and TTPC) identified for consideration in this HHRA are persistent, bioaccumulative and toxic, hence there are no secondary pathways of concern (such as accumulation in crops and produce, and subsequent human consumption) that require quantification. Sodium polyacrylate is limited in biodegradability potential, however it is not bioaccumulative and essentially non-toxic to receptors and hence secondary pathways of concern are not complete. While sodium hypochlorite, MIT and CMIT meets the screening criteria for toxicity, qualified by its acute toxicity capacity, adverse chronic outcomes are not evident based on its reactivity and lack of persistence and bioaccumulation in the environment. Limited information is available for TTPC however

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acute toxicological data available suggests that TTPC does meet the screening criteria for toxicity. Primary adverse health effects associated with the use of TTPC (as a pure substance) are related to irritant and corrosive properties for the skin, eyes, nose and lungs. It is to be noted that Worker exposures of TTPC are addressed through the implementation of appropriate occupational health and safety procedures and management plans. Considering the significant dilution, sorption and biodegradation processes that occur in the coal seam, it is not expected that such properties of TTPC would be realised in the flowback water.

• During the pilot operations, flow back water, removed from the well, are pumped and temporarily stored in open topped 75,000L rectangular storage tanks to allow particulate/solid removal (i.e. sand), after which the fluid would be transferred into the 6 ML circular holding tanks, located approximately 600 m from the well site. These holding tanks include fluid level monitoring devices which automatically shut down pumps upon reaching high level; the designated tank high fluid level includes a freeboard buffer for rain. These holding tanks are double-lined with galvanised steel frame. Holding tanks are inspected monthly for leaks. Holding tanks are secured with perimeter fencing, with locked and signage. While it is expected that the holding tanks are not accessible to the public, exposure may occur if trespassers enter the tanks, or if there is a leak in the pipelines or tank and water from these infrastructure is released to the local environment. The fluid recovered during development completion operations will be produced to a tank on site and trucked to an effluent pond at a water treatment facility (WTF). After completions operations, the wells will be tied into the gathering network and the fluid will flow to the feed pond at a WTF along with the water produced at all other wells in the area.

Based on the available information, the key receptors (and exposures that are considered significant) who may be exposed to the COPC identified on and off the site include the following:

Trespassers

• Direct contact (ingestion and dermal contact) with COPC identified in flowback water contained within the flowback open top storage tanks.

A summary of AECOM’s decision tree evaluating the receptors and pathways is present in Table 22.

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Table 22 Identification of Potential Human Receptors and Pathways

Source Exposure Scenario Receptors

(On and Off-site) Pathway

Pathway Potentially Complete?

Comment

Hydraulic Fracturing Chemicals

Handling of chemicals either on or off-site (i.e. during transportation of chemicals to the site), spills and leaks.

On and off-site workers Ingestion, dermal

No OH&S procedures and spill containment adequately address this exposure.

Hydraulic Fracturing Fluids

Fracturing fluid escapes into aquifer (well casing failure, fault, and fracture, unconformity in seam or strata) and enters a water bore used for beneficial use.

Off-site residents Ingestion, dermal

No

Origin has detailed operational procedures that are designed to contain hydraulic fracturing fluids within the coal seam. No direct connection is understood to exist between groundwater in the coal seams and surface-water, aquifers utilised for the purpose of extraction (refer Section 2.2.4).

Furthermore fate and transport modelling indicates COPC migration is minimal within the coal sequence (refer Section 3.5).

Disposal Pit Sediments

(i.e. sand, tracer beads)

Entry into pit Workers, trespassers Ingestion, dermal

No OH&S procedures limit workers exposure to sediment. Pit will be capped with clay overburden to prevent workers and trespassers exposure to sediments.

Pit sediments dry and become windblown dust

Workers, trespassers Inhalation of dust

No Pit will be capped with clay immediately after sediment disposal.

Flowback Water

Deliberate entry into holding tanks

Trespassers Ingestion,

dermal Yes

Trespassers entry is limited via fencing and signage around the drill pad areas. In addition, the walls of the holding tanks are at least 2 m high. Access ladders on the side of the holding tanks exist. As such, this pathway has been evaluated as part of this assessment.

Working with the holding tanks (i.e. drainage of holding tanks)

Workers Ingestion,

dermal No OH&S procedures limit workers exposure to flow back water.

Spills and leaks, holding tank overflow system failure

Workers Ingestion,

dermal No OH&S procedures limit workers exposure to flow back water.

Shaded cells indicate potentially complete exposure pathway, assessed as part of this HHRA.

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4.3 Quantification of Exposure When calculating chemical intake or exposure, the risk assessment process focuses on exposure occurring over a prolonged period; that is, chronic exposure that occurs over years and possibly a lifetime. The following steps have been followed to estimate chemical intake:

• Calculation of intake factors for each of the identified exposure pathways and receptors. An intake factor is a site-specific and receptor-specific value which, when multiplied by the concentration of each COPC, provides an estimate of the daily chemical intake of the COPC for each receptor and pathway. Some examples include inhalation rate, exposure frequency (i.e. hours per day or days per year) and exposure duration (e.g. number of years as a resident) and body weight; and

• Estimation of the chemical concentration in each medium relevant to the receptor groups and exposure pathways. This involves the use of relevant data collected from the site and surrounds.

The assessment presented has addressed potential worst-case exposure to COPC, and exposure has been calculated for a Reasonable Maximum Exposure (RME) scenario estimated by using the intake factors and chemical concentrations that define the highest exposure that is reasonably likely to occur in the area assessed. The RME is likely to provide a conservative estimate of total exposure and therefore health risk.

4.3.1 Exposure Parameters

Exposure parameters which are considered representative of RME have been selected for the receptor groups evaluated; namely trespassers. Where available, exposure parameters have been obtained from Australian sources (CRC care 2011; enHealth 2012; NEPC 2013). As required, this has been supplemented with data from the US EPA (2008 and 2009).

The exposure assumptions adopted are consistent with the typical exposure assumptions utilised by enHealth (2012) for recreational exposure. The exposure parameters adopted also partially reflect that storage of flow back water at individual well pad sites will be only a temporary activity and only during pilot operations, with operational controls and activities at the well sites likely limiting the occurrence of trespasser entry and exposures.

The following Table 23 presents an overview of the parameters selected. These parameters, as well as relevant references, are utilised in the exposure models presented in Appendix E. Table 23 Exposure Parameters – Trespassers

Exposure Factor Units Trespasser Reference

Exposure Frequency

Days/year 5 days during any one year, for a period of 10 separate years

Professional judgement

Exposure Duration Year 10 years for adults and children


Exposure Time Outdoors

Hours/day 1 hour


Surface Area cm2 20,000 cm2 for adults, 15,900 cm2 for children. Exposure is assumed to be equal to that of swimming, where the whole body gets wet

enHealth 2012

Body Weight kg 78 kg for adults, 39 kg for children enHealth 2012

4.3.2 Exposure Point Concentrations

Exposure Point Concentrations (EPC) of COPC requiring further assessment, as identified on the basis of theoretical or empirical data are presented in Table 10 to Table 16.

4.3.3 Exposure Equations

The following equations were used for calculating the intake of COPC:

Ingestion of water:

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𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷 𝐶𝐶ℎ𝑒𝑒𝑒𝑒𝐷𝐷𝑒𝑒𝐷𝐷𝐷𝐷 𝐼𝐼𝐼𝐼𝐼𝐼𝐷𝐷𝐼𝐼𝑒𝑒 (𝐷𝐷𝑖𝑖) = 𝐶𝐶𝑖𝑖 𝑥𝑥 𝐼𝐼𝐼𝐼𝑖𝑖 𝑥𝑥 𝐸𝐸𝐸𝐸 𝑥𝑥 𝐸𝐸𝐷𝐷

𝐵𝐵𝐵𝐵 𝑥𝑥 𝐴𝐴𝐴𝐴

Dermal contact with water:

𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷 𝐶𝐶ℎ𝑒𝑒𝑒𝑒𝐷𝐷𝑒𝑒𝐷𝐷𝐷𝐷 𝐼𝐼𝐼𝐼𝐼𝐼𝐷𝐷𝐼𝐼𝑒𝑒 (𝑑𝑑𝑖𝑖) = 𝐶𝐶𝑖𝑖 𝑥𝑥 𝑆𝑆𝐴𝐴𝑖𝑖 𝑥𝑥 𝐸𝐸𝐴𝐴 𝑥𝑥 𝐷𝐷𝐷𝐷 𝑥𝑥 𝐶𝐶𝐸𝐸 𝑥𝑥 𝐸𝐸𝐸𝐸 𝑥𝑥 𝐸𝐸𝐷𝐷

𝐵𝐵𝐵𝐵 𝑥𝑥 𝐴𝐴𝐴𝐴

Where:

CW = concentration in water (mg/l) ET = exposure time (hr/day) EF = exposure frequency (day/yr) ED = exposure duration (years) CF = correction factor (0.001 L/cm3) AT = Averaging time (days) IR = Ingestion rate (L/hr)

BW = body weight (kg) SA = skin surface area (cm2/d) DP = dermal permeability factor (cm/hr)

The calculations undertaken to estimate intake via ingestion and dermal absorption are presented in Appendix E.

4.4 Human Health Risk Assessment For those COPC (refer to Tables 10 to 16) for which potentially complete exposure pathways have been identified (refer to Table 22), there is a need to quantitatively assess the magnitude of potential exposure with regard to tolerable intakes.

The human health risk assessment (HHRA) was undertaken in general accordance with the following protocols and guidance:

• Amended National Environment Protection (Assessment of Site Contamination) Measure 1999 (Amended ASC NEPM); Schedule B4, Site-specific health risk assessment methodology (NEPC 2013);

• Environmental Health Risk Assessment: Guidelines for Assessing Human Health Risks from Environmental Hazards (enHealth 2012a). These guidelines draw on and are supplemented by those provided by a number of other Australian and international agencies, with some of the key supporting documents listed below:

- Methodology for setting air quality standards in Australia (NEPC 2011); and

- Science and decisions: Advancing risk assessment (NRC 2008).

Human health risk assessment can be divided into the following four tasks:

• Issue Identification

• Hazard/Toxicity Assessment

• Exposure assessment.

• Risk characterisation

Guidance provided by enHealth (and detailed by NEPC) is utilised as the primary source. However, where only general guidance for the completion of risk assessment tasks (above) is provided, more detailed protocols and guidelines developed by the National Research Council (NRC 2008) and United States Environment Protection Agency (US EPA) (1989, 1991, 2002, 2005 and 2009) have been used as supplementary guidance.

It is noted that the HHRA approach presented in this report provides a methodology for assessment of the risks posed by mixtures that meet the requirement in the EA consent conditions. This approach evaluates the toxicity of the individual substances and characterises the cumulative risks of the total

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effluent toxicity and ecotoxicity, which is consistent with the National Water Quality Management Strategy (NWQMS) and the principles outlined in the ANZECC & ARMCANZ (2000) guidelines.

4.4.1 Toxicity Assessment – Human Health

The objective of the toxicity assessment is to identify toxicity values for the COPC that can be used to quantify risks to human health associated with the calculated intake. The quantification of risk requires identification of toxicity values for the COPC identified as well as quantification of potential exposure.

Toxicity can be defined as “the quality or degree of being poisonous or harmful to plant, animal or human life” (NEPC 2013).

The steps involved in this process include the following:

• Obtain relevant qualitative and quantitative toxicity information on the COPC relevant to the significant exposure pathways being assessed.

• Identify the appropriate toxicity values for assessing both threshold1 effects and non-threshold carcinogenic2 effects.

4.4.1.1 Selection of Toxicity Values

The identification of toxicity values undertaken in this risk assessment has followed ANZECC (1992) guidance, which is in accordance with the NEPC (1999) policy. enHealth (2004) provides a list of toxicological data sources. These are classified as Level 1 or 2 data, with Level 1 sources recommended. In order of preference, the Level 1 sources are:

1. National Health and Medical Research Council documents and documents from other joint Commonwealth, State and Territory organisations.

2. ADI List from the Therapeutic Goods Administration.

3. World Health Organisation (WHO) documents.

4. enHealth Council documents.

5. National Environmental Health Forum documents.

6. International Agency for Research on Cancer (IARC) monographs.

7. WHO/FAO Joint Meeting on Pesticides (JMPR) monographs.

8. NICNAS Priority Existing Chemical (PEC) reports.

9. US Agency for Toxic Substances and Disease Registry (ATSDR) documents.

10. National Toxicology Program (NTP) carcinogenicity appraisals.

11. OECD Standard Information Data Sets (SIDS) and SID Initial Assessment Reports (SIAR).

12. USEPA Reference Doses.

Level 2 sources include peer-reviewed journals and industry publications and reference to Level 2 sources is considered warranted where Level 1 sources do not provide applicable criteria.

The following types of toxicity values may therefore be applicable:

• Acceptable or Tolerable Daily Intakes (ADIs or TDIs), for assessment of non-cancer effects (ANZECC, NHMRC and WHO);

• Benchmark doses, for assessment of cancer effects (ANZECC); Threshold toxicity effects are assessed on the basis that there is a dose of the chemical below which toxic effects will not occur (i.e., the threshold). 2 Non-threshold carcinogenic effects assume that, for some chemicals classified as carcinogenic, there is no threshold below which there will be no increased risk of a toxic effect. Hence, assessment of these chemicals is based on the use of a slope factor, which assumes that any exposure to the chemicals will result in an increased incremental risk or probability of developing cancer over a lifetime.

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• Reference Concentrations (RfC), for inhalation assessment of non-cancer effects (USEPA);

• Reference Doses (RfD), for oral assessment of non-cancer effects (USEPA); and

• Cancer slope factors, for assessment of cancer effects (WHO and USEPA).

Potential threshold effects are characterised by comparing the estimated chemical intakes with the ADIs, TDIs or RfDs, that represent the threshold intake for adverse health effects. Threshold toxicity effects are assessed on the basis that there is a dose of the chemical below which toxic effects will not occur (i.e., the threshold).

Potential non-threshold carcinogenic effects are the estimated incremental probabilities that an individual will develop cancer over a lifetime as a result of the estimated exposure to the COPC. When a carcinogenic slope factor is used to evaluate health risk, it is assumed that any exposure to the chemical will, in theory, result in an increased risk or probability of developing cancer. The higher the carcinogenic slope factor, the more potent the chemical, and the greater the calculated cancer risk for a given exposure.

In reviewing relevant toxicity information for the COPC identified in this HHRA, the following has also been considered in the approach adopted:

• Assessment of Dermal Exposures: No dermal toxicity values are available for the COPC identified. While it is not considered appropriate to undertake route-route extrapolation, the adoption of oral toxicity values (with relevant consideration of bioavailabilities) has been identified and considered appropriate by USEPA (2004) in the absence of dermal data. Hence, dermal exposures have been assessed on the basis of oral data, where available

• Assessment of Oral Exposures: In relation to potential exposure and risk issues identified and evaluated in this assessment, the key route of exposure is via ingestion and direct contact with COPC in water (Section 3.3.1). Hence, the oral TRV is utilised for the purpose of establishing drinking water (or recreational water) guidelines. Existing oral TRVs and drinking water guideline values were used when applicable. Otherwise, information on mammalian toxicity was acquired primarily from reported data that had already been through a screening process such as the OECD SIDS program, the U.S. Cosmetics Ingredient Review or the EU Scientific Committee on Consumer Safety (SCCS). The data from these programs were considered sufficiently reviewed as to not require further evaluation. Data reported as part of other equivalent peer reviewed risk assessment programs (e.g., HHRA (www.HHRAproject.com/); USEPA HPV Chemical Challenge Program) were also considered in a similar fashion, although a certain level of expert judgment was required to evaluate the quality of these programs. Toxicity information was also obtained via the ECHA CHEM database. This database provides electronic public access to information on chemical substances manufactured or imported in Europe. The information originates from the registration dossiers submitted by companies to ECHA in the framework of REACH Regulation. If no data were available from the above sources or the available data were considered insufficient for the determination of oral RfDs and drinking water guideline values, then toxicity information on MSDSs were used, as well as read-across from available experimental data on a structurally related substances, and predicted values from QSAR models. With exception to the USEPA integrated risk information system (IRIS) values, the most appropriate or reliable NOAEL or LOAEL, if a NOAEL was unavailable, and the critical effect were identified.

4.4.2 Derivation of oral reference dose and drinking water guideline values

4.4.2.1 Oral Toxicity Reference Value derivation

Where required, the oral reference dose was calculated using the following equation:

𝑂𝑂𝑂𝑂𝐷𝐷𝐷𝐷 𝐴𝐴𝐼𝐼𝑇𝑇 = 𝑁𝑁𝑂𝑂𝐴𝐴𝐸𝐸𝑁𝑁 (𝑜𝑜𝑂𝑂 𝑁𝑁𝑂𝑂𝐴𝐴𝐸𝐸𝑁𝑁)

𝑈𝑈𝐸𝐸𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇

Where:

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NOAEL = No Observed Adverse Effect Level LOAEL = Lowest Observed Adverse Effect Level UFTotal = Total uncertainty factors

When dosing regimens were 5 days/week, the NOAEL was adjusted to 7 days/week by multiplying the NOAEL by 5/7.

Uncertainty factors of 10 were used to account for the following (USEPA, 2002):

• Variation in sensitivity among members of the human population, i.e., inter-individual variability:

• Uncertainty in extrapolating animal data to humans, i.e., interspecies uncertainty;

• Uncertainty in extrapolating data obtained in a study with less-than-lifetime exposures, i.e., extrapolating from subchronic to chronic exposure; and.

• Uncertainty in extrapolating from a LOAEL rather than from a NOAEL.

4.4.2.2 Determination of drinking water guideline values

The ADWG (2016) values were used when applicable. The WHO, and then USEPA, were also consulted for any additional drinking water standards when there were no ADWGs.

For those chemicals where there are no regulatory drinking water guidelines, and for which a threshold exists, the guideline value was derived from animal toxicity data using the following equation (ADWG, 2016):

𝐷𝐷𝑂𝑂𝐷𝐷𝐼𝐼𝐼𝐼𝐷𝐷𝐼𝐼𝐷𝐷 𝐵𝐵𝐷𝐷𝐼𝐼𝑒𝑒𝑂𝑂 𝐶𝐶𝑂𝑂𝐷𝐷𝐼𝐼𝑒𝑒𝑂𝑂𝐷𝐷𝐷𝐷

= 𝑁𝑁𝑂𝑂𝐴𝐴𝐸𝐸𝑁𝑁 (𝑜𝑜𝑂𝑂 𝑁𝑁𝑂𝑂𝐴𝐴𝐸𝐸𝑁𝑁)𝑥𝑥 𝐵𝐵𝑜𝑜𝑑𝑑𝐷𝐷 𝐵𝐵𝑒𝑒𝐷𝐷𝐷𝐷ℎ𝐼𝐼 𝑥𝑥 𝐷𝐷𝑂𝑂𝑜𝑜𝑃𝑃𝑜𝑜𝑂𝑂𝐼𝐼𝐷𝐷𝑜𝑜𝐼𝐼 𝐷𝐷𝐼𝐼𝐼𝐼𝐷𝐷𝐼𝐼𝑒𝑒 𝑓𝑓𝑂𝑂𝑜𝑜𝑒𝑒 𝑖𝑖𝐷𝐷𝐼𝐼𝑒𝑒𝑂𝑂

𝑣𝑣𝑜𝑜𝐷𝐷𝑣𝑣𝑒𝑒𝑒𝑒 𝑜𝑜𝑓𝑓 𝑖𝑖𝐷𝐷𝐼𝐼𝑒𝑒𝑂𝑂 𝑒𝑒𝑜𝑜𝐼𝐼𝑐𝑐𝑣𝑣𝑒𝑒𝑒𝑒𝑑𝑑 𝑥𝑥 𝑈𝑈𝐸𝐸𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇

Where:

NOAEL = No Observed Adverse Effect Level LOAEL = Lowest Observed Adverse Effect Level Body weight = 78 kg Proportion of intake from water = 10% Volume of water consumed = 2 L/day UFTotal = Total Uncertainty Factors

4.4.3 Summary of Toxicity Reviews

Quantitative toxicity values identified/derived and the drinking water guidelines identified/derived for site related COPC were adopted in accordance with guidance available from enHealth (2012), ADWG (2016) and NEPM (2013). Appendix C provides further toxicity information on each of the COPC. Table 24 provides a summary of the quantitative toxicity values for oral and dermal exposures and the drinking water criteria for the COPC identified.

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Table 24 Toxicity Data for Chronic Oral/Dermal Exposures and Drinking Water Screening Criteria for COPC

CAS Chemical Non-Threshold Slope Factor (mg/kg/day)-1

Threshold Chronic TDI (mg/kg/day)

Dermal Permeability (cm/hr)

Drinking Water Guideline (mg/L)

COPC in Hydraulic Fracturing Fluid Injected into Well

26172-55-4 5-chloro-2-methyl-2h-isothiazolol-3-one (Methylchloroisothiazolinone)

-- 0.020 D 1.40E-04 0.078 D

2682-20-4 2-methyl-2h-isothiazol- 3-one (Methylisothiazolinone)

-- 0.020 D 1.00E-04 0.078 D

9000-30-0 Guar gum -- 12.5 D -- 49 D

9025-56-3 Hemicellulase enzyme -- 0.600 D -- 2.3 D

26038-87-9 MEA borate -- 1.000 D 1.80E-05 3.9 D

10043-01-3 Aluminium sulfate -- 0.050 D -- 0.18 A (Al)

9012-54-8 Cellulase enzyme -- 0.600 D -- 2.3 D

151-21-3 Sodium lauryl sulfate -- 1.100 D 4.40E-04 4.4 D

9005-64-5 Sorbitan, monododecanoate, poly(oxy-1,2-diethanediyl)

-- 25.000 D -- 98 D

63-42-3 Lactose -- 1.000 D 9.20E-09 3.9 D

h68308-35-8 Shellac, ammonium salt -- 0.500 D 2.70E-15 2.0 D

61789-40-0 1-Propanaminium, 3-amino-n-(carboxy methyl)-n,n-dimethyl-n-coco alkyl

-- 0.054 D 5.40E-05 0.19 D

111-30-8 Glutaraldehyde -- 0.040 D 3.25E-04 0.016 D

56-81-5 Glycerol -- 100 D 3.22E-05 39 D

9003047 Sodium polyacrylate -- 3.000 D 11.7 D

1332-77-0 Potassium borate -- 0.054 D 1.00E-03 3.5 (as boron) A

77-92-9 Citric acid -- 12.000 D 4.7 D

7447-40-7 Potassium Chloride 18.20 D 71 D

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CAS Chemical Non-Threshold Slope Factor (mg/kg/day)-1

Threshold Chronic TDI (mg/kg/day)

Dermal Permeability (cm/hr)

Drinking Water Guideline (mg/L)

COPC identified in Flowback Water Analysis from Current Operations

71-43-2 Benzene 3.50E-02 WHO 0.004 USEPA 0.015 0.001 A

7440-39-3 Barium -- 0.067 A 1.00E-03 2 A

-- TPH >C16-C34 -- 1.015 T 1.80E-01 0.09 W Notes: D – Derived; A – ADWG 2016; W – WHO 2011; J-JECFA; -- Not available

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4.5 Risk Characterisation 4.5.1 Risks to Human Health

Risk characterisation is the final step in a quantitative risk assessment. It involves the incorporation of the exposure assessment and toxicity assessment to provide a quantitative assessment of non-threshold carcinogenic risk and threshold risk. In the assessment presented, evaluation of exposures to the COPC involves an assessment of threshold and non-threshold risks.

The calculation of risks has been undertaken using an in-house spreadsheet model, RiskE (version 2011). The equations utilised within RiskE follow risk assessment methodology as outlined in Section 6.1 following protocols established by ANZECC, NHMRC, NEPM and CRC CARE. The output from this model has been incorporated into the tables presented, and calculation sheets are presented in Appendix E.

4.5.1.1 Hazard Index for Threshold Effects

The potential for adverse threshold effects, resulting from exposure to an individual COPC, has been evaluated by comparing an exposure level, expressed as a daily chemical intake, with the ADI/TDI or RfD. The resulting ratio is referred to as the hazard quotient, and is derived in the following manner for oral/dermal and inhalation exposures:

𝐻𝐻𝐷𝐷𝐻𝐻𝐷𝐷𝑂𝑂𝑑𝑑 𝑄𝑄𝑣𝑣𝑜𝑜𝐼𝐼𝐷𝐷𝑒𝑒𝐼𝐼𝐼𝐼 (𝑜𝑜𝑂𝑂𝐷𝐷𝐷𝐷 𝑜𝑜𝑂𝑂 𝑑𝑑𝑒𝑒𝑂𝑂𝑒𝑒𝐷𝐷𝐷𝐷) = 𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷 𝐶𝐶ℎ𝑒𝑒𝑒𝑒𝐷𝐷𝑒𝑒𝐷𝐷𝐷𝐷 𝐼𝐼𝐼𝐼𝐼𝐼𝐷𝐷𝐼𝐼𝑒𝑒

(𝐴𝐴𝐷𝐷𝐼𝐼,𝐴𝐴𝐷𝐷𝐼𝐼,𝐼𝐼𝑓𝑓𝐷𝐷 − 𝐵𝐵𝐷𝐷𝑒𝑒𝐼𝐼𝐷𝐷𝑂𝑂𝑜𝑜𝑣𝑣𝐼𝐼𝑑𝑑)

Where

ADI = acceptable daily intake (mg/kg/day) TDI = tolerable daily intake (mg/kg/day) RfD = Reference dose (mg/kg/day)

If the daily chemical intake for the individual COPC exceeds the ADI, TDI or RfD (i.e. if the hazard quotient exceeds one), then this would indicate potentially unacceptable chemical intakes. The hazard quotient does not represent a statistical probability of an effect occurring.

To assess the overall potential for adverse health effects posed by simultaneous exposure to multiple chemicals, the hazard quotients for each chemical and exposure pathway have been summed. The resulting sum is referred to as the hazard index (HI). The HI approach assumes that multiple sub-threshold exposures to several chemicals could result in a cumulative adverse health effect, and exposures are summed over all intake routes.

Acceptable Risk

An “acceptable” risk in this assessment has been defined as a Hazard Index of 1 (as per risk assessment industry practice, supported by protocols outlined in NEPM (2013) and USEPA guidance.

If the Hazard Index is less than one, cumulative exposure to the site chemicals is judged unlikely to result in an adverse effect. If the index is greater than one, a more detailed and critical evaluation of the risks (including consideration of specific target organs affected and mechanisms of toxic action of the chemicals of concern) would be required to ascertain if the cumulative exposure would, in fact, be likely to harm exposed individuals. All hazard quotient and hazard index calculations are presented in Appendix E.

4.5.1.2 Non-Threshold Carcinogenic Risk

The potential for unacceptable non-threshold carcinogenic risks associated with exposure to COPC have been evaluated using US EPA (1989 and 2009) methodology.

Non-threshold carcinogenic risks are estimated as the incremental probability of an individual developing cancer over a lifetime as a result of exposure to a potential non-threshold carcinogen. The numerical estimate of excess lifetime cancer risk is calculated as follows for oral/dermal and inhalation exposures:

𝐶𝐶𝐷𝐷𝑂𝑂𝑒𝑒𝐷𝐷𝐼𝐼𝑜𝑜𝐷𝐷𝑒𝑒𝐼𝐼𝐷𝐷𝑒𝑒 𝐼𝐼𝐷𝐷𝑐𝑐𝐼𝐼 (𝑜𝑜𝑂𝑂𝐷𝐷𝐷𝐷 𝑜𝑜𝑂𝑂 𝑑𝑑𝑒𝑒𝑂𝑂𝑒𝑒𝐷𝐷𝐷𝐷) = 𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷 𝐶𝐶ℎ𝑒𝑒𝑒𝑒𝐷𝐷𝑒𝑒𝐷𝐷𝐷𝐷 𝐼𝐼𝐼𝐼𝐼𝐼𝐷𝐷𝐼𝐼𝑒𝑒 𝑥𝑥 𝐶𝐶𝐷𝐷𝐼𝐼𝑒𝑒𝑒𝑒𝑂𝑂 𝑆𝑆𝐷𝐷𝑜𝑜𝑃𝑃𝑒𝑒 𝐸𝐸𝐷𝐷𝑒𝑒𝐼𝐼𝑜𝑜𝑂𝑂

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The total non-threshold carcinogenic risk is the sum of the risk for each chemical for each pathway.

Australian guidance related to the significance of non-threshold cancer risk estimates currently specifies that risks of less than 10-5 per lifetime is generally accepted as indicating conditions that do not warrant specific management or remedial action.

Acceptable Risk

The adopted acceptable risk is defined as a risk of less than 1 x 10-5 incremental lifetime risk of cancer.

4.5.2 Summary of Risk

A summary of the calculated risks for the identified receptor group (trespassers) that are relevant to the detailed assessment of potential exposure to COPCs on-site, based on the available data is presented Table 25 to Table 29. Table 25 Risk associated with potential exposure to trespassers – hydraulic fracturing fluid

system (theoretical and empirical data)

Receptor and Pathway

Non-Threshold Carcinogenic Risk

Threshold Hazard Index



20% Mass Return 60% Mass Return water-based hydraulic fracturing fluid system - COPC associated with

theoretical data

Adult Trespassers Ingestion of chemicals via incidental contact with flowback water NA 0.00040 NA 0.0012

Dermal exposure to chemicals via incidental contact with flowback water NA 0.000021 NA 0.000064

Total Risk NA 0.0004 NA 0.001

Child Trespassers Ingestion of chemicals via incidental contact with flowback water NA 0.00079 NA 0.0025


Total Risk NA 0.001 NA 0.003 water-based hydraulic fracturing fluid system - COPC associated with empirical

data

Adult Trespassers Ingestion of chemicals via incidental contact with flowback water 2.6E-10 0.00095 2.6E-10 0.00095

Dermal exposure to chemicals via incidental contact with flowback water 1.6E-09 0.00084 1.6E-09 0.00084

Total Risk 2E-09 0.002 2E-09 0.002

Child Trespassers Ingestion of chemicals via incidental contact with flowback water 5.3E-10 0.0019 5.3E-10 0.0019

Dermal exposure to chemicals via incidental contact with flowback water 2.5E-09 0.0013 2.5E-09 0.0013

Total Risk 3E-09 0.003 3E-09 0.003

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Notes: Risk values have been rounded to two significant figures with totals rounded to one significant figure; hence, the sum of individual risks may not add up exactly to the total presented. NA = Not Assessed as there are no non-threshold COPC in the media of concern The following can be noted from the table above:

• The calculated risks associated with potential exposure to COPC identified in flowback water,where water stimulation fluid is used and assuming 20% or 60% mass recovery, are below thetargets of 1 x 10-5 and 1, respectively. Hence, risks are considered to be low and acceptable.

• The calculated risk to trespassers associated with exposure to COPC that may be present in flowback water, as determined from empirical data obtained from existing operations, is below thetargets of 1 x 10-5 and 1, respectively. Hence, risks are considered to be low and acceptable.

Table 26 Risk associated with potential exposure to trespassers – hydraulic fracturing fluid system (theoretical and empirical data)






20% Mass Return 60% Mass Return gel-based hydraulic fracturing fluid system - COPC associated with theoretical data

Adult Trespassers

Ingestion of chemicals via incidental contact with flowback water NA 0.0045 NA 0.014



Child Trespassers




gel-based hydraulic fracturing fluid system - COPC associated with empirical data

Adult Trespassers

Ingestion of chemicals via incidental contact with flowback water

2.6E-10 0.00095 2.6E-10 0.00095

Dermal exposure to chemicals via incidental contact with flowback water

1.6E-09 0.00084 1.6E-09 0.00084

Total Risk 2E-09 0.002 2E-09 0.002

Child Trespassers


5.3E-10 0.0019 5.3E-10 0.0019


2.5E-09 0.0013 2.5E-09 0.0013

Total Risk 3E-09 0.003 3E-09 0.003

Notes:

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Risk values have been rounded to two significant figures with totals rounded to one significant figure; hence, the sum of individual risks may not add up exactly to the total presented. NA = Not Assessed as there are no non-threshold COPC in the media of concern

The following can be noted from the table above:

• The calculated risks associated with potential exposure to COPC identified in flowback water,where gel stimulation fluid is used and assuming 20% or 60% mass recovery, are below thetargets of 1 x 10-5 and 1, respectively. Hence, risks are considered to be low and acceptable.









Adult Trespassers




Child Trespassers





Adult Trespassers


2.6E-10 0.00095 2.6E-10 0.00095


1.6E-09 0.00084 1.6E-09 0.00084

Total Risk 2E-09 0.002 2E-09 0.002

Child Trespassers


5.3E-10 0.0019 5.3E-10 0.0019


2.5E-09 0.0013 2.5E-09 0.0013

Total Risk 3E-09 0.003 3E-09 0.003

Notes:

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Adult Trespassers




Child Trespassers





Adult Trespassers


2.6E-10 0.00095 2.6E-10 0.00095


1.6E-09 0.00084 1.6E-09 0.00084

Total Risk 2E-09 0.002 2E-09 0.002

Child Trespassers


5.3E-10 0.0019 5.3E-10 0.0019


2.5E-09 0.0013 2.5E-09 0.0013

Total Risk 3E-09 0.003 3E-09 0.003

Notes:

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20% Mass Return 60% Mass Return gel-based hydraulic fracturing fluid system - COPC associated with theoretical

Adult Trespassers




Child Trespassers




hydraulic fracturing fluid system - COPC associated with empirical data

Adult Trespassers


2.6E-10 0.00095 2.6E-10 0.00095


1.6E-09 0.00084 1.6E-09 0.00084

Total Risk 2E-09 0.002 2E-09 0.002

Child Trespassers


5.3E-10 0.0019 5.3E-10 0.0019


2.5E-09 0.0013 2.5E-09 0.0013

Total Risk 3E-09 0.003 3E-09 0.003

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Notes: Risk values have been rounded to two significant figures with totals rounded to one significant figure; hence, the sum of individual risks may not add up exactly to the total presented. NA = Not Assessed as there are no non-threshold COPC in the media of concern


• The calculated risks associated with potential exposure to COPC identified in flowback water, where gel stimulation fluid is used and assuming 20% or 60% mass recovery, are below the targets of 1 x 10-5 and 1, respectively. Hence, risks are considered to be low and acceptable.

• The calculated risk to trespassers associated with exposure to COPC that may be present in flow back water, as determined from empirical data obtained from existing operations, is below the targets of 1 x 10-5 and 1, respectively. Hence, risks are considered to be low and acceptable.

4.6 Conclusions The quantification of potential risks to human health associated with the use of chemicals in well simulation activities conducted by Origin within the project area has involved the assessment of potential exposures to compounds used or formed in the simulation activities. Based on the conceptual site model, operational controls, security and management practices implemented by Origin, the potentially complete exposure pathway identified and assessed in the risk assessment was the incidental ingestion and dermal contact by trespassers at the flowback fluid holding tanks.

On the basis of the conservative assessment undertaken with consideration of the uncertainties identified in Section 7.0, it can be concluded that there are no unacceptable potential health risks to trespassers were identified in relation to potential exposures to flowback water from well simulation activities.

Effective operational controls and management implemented by Origin further minimises potential exposures to trespassers. These operational controls include:

• Fencing and signage around the flowback storage tanks

• Routine operational and security patrols to prevent trespassing

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5.0 Quantitative Environmental Risk Assessment The objective of undertaking an Environmental Risk Assessment (ERA) is to investigate the potential risks to the environment associated with the concentrations of chemicals of potential environmental concern (COPEC) that may be present in the flowback water (in the event there is a leak or spill from aboveground infrastructure).

With regards to the assessment of potential environmental risks, the requirements of the Amended ASC NEPM Schedule B5a, Guideline on Ecological Risk Assessment (NEPC 2013) were considered.

Similar to the HHRA, the ERA consists of the four basic components:

• Issue Identification/Problem Formulation:

- Identification of COPECs;

- Identification of receptors of concern; and

- Identification of operable exposure pathways warranting quantification of risk.

• Toxicity Assessment:

- Present the doses or concentrations of COPECs below which risks are assumed to be negligible or low (toxicological reference values, TRVs);

• Exposure Assessment:

- Determination of exposure concentrations for the site’s various receptors (i.e. concentrations used to quantify risks); and

- Estimation of contaminant intake (dose entering body, mg/kg-day) for operable exposure pathways.

• Risk Characterisation:

- Quantify risks as magnitude of exceedance of the TRVs (i.e. hazard quotients, dose divided by TRV) and derivation of species sensitivity distributions.

It is noted that the ERA approach presented in this report provides a methodology for assessment of the risks posed by mixtures that meet the requirement in the EA consent conditions. This approach evaluates the toxicity of the individual substances and characterises the cumulative risks of the total effluent toxicity and ecotoxicity, which is consistent with the National Water Quality Management Strategy (NWQMS) and the principles outlined in the ANZECC & ARMCANZ (2000) guidelines. The NEPC (2013) also addresses the mixture of constituents and has adopted the hazard quotient approach for the Guideline for ERA.

As presented in Section 3.2.2, flowback water from the hydraulic fracturing process potentially contains hydraulic fracturing chemicals and chemical constituents naturally present within groundwater from the coal seams. Similar to the human health risk assessment approach, the estimated exposure to the flow back water was based on a theoretical and empirical EPC that was developed either from knowledge of the chemicals and quantities used in the hydraulic fracturing process, or the results of laboratory analysis of return water from existing operations.

5.1 Exposure Assessment The exposure setting provides important information regarding the current site use and physical attributes of the site. The information herein will form the basis for determining applicable exposure pathways between sources of contamination and receptors of concern (assessment endpoints). The objective of the environmental risk assessment is to assess the typical potential exposures that may occur in any of the operational areas in the CSG fields. As such, the exposure assumptions for the environmental receptors were based on a typical operational layout and adjacent land use that includes agricultural land and a flowing surface water body.

For the purpose of this ERA, the study area is divided into the operational area and the offsite agricultural area.

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The operational area is considered a highly modified system (i.e. the site has been extensively cleared, with gravel and compacted soil covering the well pad and around infrastructure) that has minimal wildlife habitat to support a functioning aquatic or terrestrial ecosystem including foraging and breeding habitat. In addition, the operational controls, security and management practices implemented by Origin, such as the installation and maintenance of fences around the operational site, would limit the exposure of environmental receptors to the hydraulic fracturing fluids considered in this assessment. It is noted that there may be occasional incursions of wildlife into the operational area. However, as the flow back water will be contained inside a holding tank (with at least 2 m high walls), there would be minimal opportunity for environmental receptors to come into contact with the with the flowback water.

The adjacent areas comprise of unimproved pastures and remnant native vegetation, both of which are used for cattle grazing purposes. A range of surface water systems that include streams, creeks dams and rivers also exist nearby. Despite that fact that the clearing and farming practices has diminished the overall habitat quality, the adjacent areas are still suitable to support indigenous flora and fauna.

5.2 Potential Exposure Pathways and Receptors Environmental surveys were conducted for Origin that identified flora and fauna that may inhabit the local and regional environments associated with the gas fields. As presented in the conceptual site model, the potential environmental receptors include domesticated livestock, agricultural and native plants, local and regional wildlife, and aquatic fish and invertebrates. However, as previously noted, the objective of this ERA is to evaluate the potential risks from a typical gas well field; therefore, the selection of environmental receptors for this ERA is based on understanding that the selected environmental receptors all have an equal opportunity to be exposed to residual hydraulic fracturing flowback water at any of the CSG fields within the project area.

Taking into account the environment at and within the vicinity of the CSG operations evaluated in this assessment, the scope of the risk assessment, the potential receptors and pathways (significant and less significant) have been identified. In reviewing and considering the potential significance of exposure pathways, the following points have been considered:

• No further assessment is considered warranted for groundwater as there are no potentially complete exposure pathways. Detailed operational procedures have been provided that are designed to contain the hydraulic fracturing fluids within the coal sequences, and no connection exists between groundwater in the coal seams and surface-water, aquifers utilised for the purpose of extraction (for any beneficial use), or springs;

• Due to the engineered controls and barriers that Origin has implemented to contain the flowback water (Section 3.2.2), no exposure pathway exists for terrestrial environmental receptors. The flowback water is contained in aboveground metal holding tanks, with walls of up to 2 metres in height. Terrestrial receptors identified to exist near the site and surrounds include domesticated livestock (cattle), large mammalian wildlife (kangaroos) and small mammalian wildlife (dingos). Notwithstanding the fences in place to deter terrestrial wildlife from entering the CSG operational area, the height of the above ground holding tanks will effectively limit their access to the flowback water. As such, the risk to terrestrial receptors has not been further assessed.

• It is noted that none of the COPC (with the exception of sodium polyacrylate, CMIT, MIT sodium hypochlorite and TTPC) identified for consideration in this HHRA are persistent, bioaccumulative and toxic, hence there are no secondary pathways of concern (such as accumulation in crops and produce, and subsequent human consumption) that require quantification. Sodium polyacrylate is limited in biodegradability potential, however it is not bioaccumulative and essentially non-toxic to receptors and hence secondary pathways of concern are not complete. While sodium hypochlorite, MIT and CMIT meets the screening criteria for toxicity, qualified by their acute toxicity capacity, adverse chronic outcomes are not evident based on their reactivity and lack of persistence and bioaccumulation in the environment. Limited information is available for TTPC, however acute toxicological data available suggests that TTPC does meet the screening criteria for toxicity. Primary adverse health effects associated with the use of TTPC (as a pure substance) are related to irritant and corrosive properties for the skin, eyes, nose and lungs. It is to be noted that Worker exposures of TTPC are addressed through the implementation of

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appropriate occupational health and safety procedures and management plans. Considering the significant dilution, sorption and biodegradation processes that occur in the coal seam, it is not expected that such properties of TTPC would be realised in the flowback water.

• Whilst considered minimal, there is the potential for a release of stored hydraulic fracturing flow back water to surface water systems located near the gas well pads in the situation of an accidental release, such as from piping, leaks or failure of overflow system in the event of heavy rainfall.

Based on the available information, the key receptors (and exposures that are considered significant) who may be exposed to the COPEC identified on and off the site includes the following:

Aquatic invertebrates and fish

• Direct contact (ingestion and dermal contact) with residual hydraulic fracturing chemicals identified in surface water in the event of a release of stored flowback fluid.

The assessment endpoints, or environmental values selected was the survival and reproduction of aquatic invertebrates. The assessment endpoints are sensitive to the residual hydraulic fracturing flow back water COPEC identified, and have the toxicological and life history databases to support their use as representatives of the study area ecosystem.

Invertebrates live on or in the sediments and surface waters depending on the substrate and trophic level. The exposure of invertebrates would result from direct contact with surface waters. Fish live in the surface waters (benthic and pelagic) and may move up and down stream with seasonal flow and to forage. Fish are exposed in the surface water through uptake via the gills, and through ingestion of invertebrates and other food items. It is noted that the assessment of potential impacts to the aquatic environment has also considered impacts to algae, a major food source for other aquatic species. A summary of AECOM’s decision tree evaluating the environmental receptors and pathways is presented in Table 30.

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Table 30 Identification of Potential Environmental Receptors and Pathways


(on and off-site)

Pathway Pathway Potentially Complete?

Comment

Hydraulic Fracturing Chemicals

Spills and leaks occur while handling of chemicals either on or off-site (i.e. during transportation of chemicals to the site)

Indigenous fauna and flora

Ingestion, dermal No OH&S procedures and spill containment adequately address this exposure.

Disposal Pit Entry into pit Indigenous fauna and flora

Ingestion, dermal, uptake

No Pit will be capped with clay to prevent exposure to sediments.

Pit sediments (i.e. sand, tracer beads) dry and become windblown dust


Inhalation of dust, ingestion, dermal, uptake

No Pit will be capped with clay immediately after sediment disposal, preventing dust accumulation.

Flowback Water

Leaks, above ground holding tank overflow system failure

Aquatic invertebrates, fish

Ingestion, dermal Yes There is the potential for a release of stored hydraulic fracturing flow back water to surface water systems located near the CSG areas in the situation of an accidental release, such as from piping, leaks or failure of overflow system in the event of heavy rainfall. However, this exposure scenario unlikely due to robust holding tank design and overflow controls implemented by Origin. Nevertheless, this pathway has been evaluated as part of this assessment.


Ingestion, dermal, uptake

No The potential for an accidental release of flow back fluid from leaking holding tanks or piping does exist (although is considered unlikely due to the operational controls and robust designs implemented by Origin), however as the operational area is considered a highly modified environment (normal operational activities, infrastructure, gravel and compacted soil cover on the well pad sites and around infrastructure would significantly inhibit the establishment/function of wildlife habitat in the immediate vicinity), the exposure pathway to indigenous flora is deemed incomplete for minor leaks and spills.

The probability of such an accidental release is further reduced due to the

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(on and off-site)

Pathway Pathway Potentially Complete?

Comment

temporary duration that the flow back fluids are stored in the holding tanks. In considering this, the likelihood that exposure to spilled or leaked flowback fluid to domestic livestock and mammalian wildlife is considered insignificant, as their exposure is not habitat driven (i.e. they would not normally forage and breed in the operational areas) and operational controls (i.e. fences) and activities at the site limiting the occurrence of livestock and wildlife entry and exposures. The potential for terrestrial receptors obtaining drinking water from leaked flow back fluid only on occasions were they to inadvertently enter onto the operational area is considered highly unlikely (i.e. the exposure frequency and duration is deemed insignificant) and hence this exposure pathway is considered effectively incomplete.

Entry into holding tanks Indigenous fauna Ingestion, dermal No Entry is limited via fencing around the operational areas. In addition, the walls of the holding tanks are at least 2 m high, which prevents access into the holding tanks.

Hydraulic Fracturing Fluids

Fracturing fluid escapes into aquifer (well casing failure, fault, fracture, unconformity in seam or strata) used for stock water supply and discharges to surface water.

Stock animals, Aquatic invertebrates, fish

Ingestion, dermal No Origin has detailed operational procedures that are designed to contain hydraulic fracturing fluids within the coal seam. No direct connection is understood to exist between groundwater in the coal seams and surface-water, aquifers utilised for the purpose of extraction (refer Section 2.2.4).

Furthermore fate and transport modelling indicates COPEC migration is minimal within the coal sequence (refer Section 3.5).

Shaded cells indicate potentially complete exposure pathway, assessed as part of this ERA.

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5.3 Toxicity Assessment 5.3.1 General

The purpose of toxicity assessment is to identify concentrations or doses of COPECs at which adverse effects may occur to receptors.

The risk characterisation performed in this ERA relies on toxicity data and screening level guidelines as toxicity reference values (TRVs). The TRVs are derived based on COPC levels that imply no adverse effects or levels that represent the lowest concentrations at which adverse effects may occur. To evaluate the concentration of the COPEC in the surface water and direct exposure by the aquatic environmental receptor, a concentration based TRV was derived.

5.3.2 Concentration Based TRV

The existing water quality guidelines for protection of aquatic life were researched and compiled using the following sources of ecotoxicological information:

• Australian and New Zealand Environment and Conservation Council (ANZEEC) guidelines for fresh and marine water quality.

• Western Australia (WA) Department of Environment and Conservation. Assessment Levels for Soil, Sediment and Water. February 2010. Contaminated Site Management Series.

• Department of Environmental and Resource Management. Approval of Coal Seam Gas Water for Beneficial Use. Environmental Protection (Waste Management) Regulation 2000. Queensland Government. March 2010.

• International Guidance (USEPA, American Petroleum Institute, Oak Ridge National Laboratory/Risk Assessment Information System (ORNL/RAIS).

If water quality guidelines were not available, information on aquatic toxicity was acquired from reported values that had already been through a screening process such as the following:

• OECD-SIDS program

• EU existing substances risk assessment

• HHRA (www.HHRAproject.com)

• USEPA HPVC Challenge Program

• ECHA CHEM database

The data from these programs were considered sufficiently reviewed as to not require further evaluation. If no data were available from the above sources or the available data were considered insufficient for TRV determinations, then toxicity information on MSDSs were used, as well as read-across from available experimental data on a structurally related substances, and predicted values from QSAR models.

5.3.3 Calculation of PNEC for freshwater

The determination of TRVs for freshwater was conducted according to the predicted no-effects concentration (PNEC) guidance in the Environmental Risk Assessment Guidance Manual for Industrial Chemicals prepared by the Australian Environmental Agency (AEA, 2009).

A PNEC is calculated using toxicity test data such as LC50, EC50, other L(E)Cx values, NOEC (no observed effect concentration) and LOEC (lowest observed effect concentration). Derivation of a PNEC commonly relies on using assessment or safety factors. Assessment factors reflect the following uncertainties inherent in most datasets, and the extrapolations that can be required:

1. Intra-species and inter-species variations

2. The extrapolation of short-term toxicity towards long-term toxicity

3. The extrapolation of laboratory results towards the field.

Table 31 lists the assessment factors used to adjust the effect concentration and to estimate a PNEC.

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Table 31 Summary of assessment factors for estimating a PNEC (AEA 2009)

Data Data Available Range of assessment factors

Comments

When only acute toxicity data are available, an assessment factor of between 100 and 1000 is applied to the lowest L(E)C50

Acute • EC50 algae (72h) • EC50 Daphnia

(24-48 h acute test) • LC50 fish (96h)

100-1000 A factor of 1000 is a conservative and protective factor and applied when only limited data are available.

A factor of 100 can be applied if the following evidence is available:

• Availability of data from a wide variety of species including those which are considered to represent sensitive species

• Information from structurally similar compounds or QSAR, to suggest that the acute to chronic ratio is likely to be low

• Information to suggest that the chemical acts in a non-specific or narcotic manner, with little inter-species variation in toxicity

• Information to suggest that the release of the chemical is short-term or intermittent, and that the chemical would not be persistent in the environment.

When chronic toxicity data are available in addition to acute data, often an assessment factor of between 10 and 100 is applied to the lowest NOEC Chronic

• NOEC Daphnia (14-21d

chronic toxicity test)

• NOEC algae (72h) NOEC

fish (chronic toxicity test)

10-100 • If a chronic NOEC is available from one or two species representing one or two trophic levels (i.e. fish, Daphnia or algae), a factor of 100 or 50 is applied to the lowest NOEC. In this case, a PNEC value derived from chronic data should be compared to that derived from the lowest acute data. It is then the lowest value that is used in the assessment.

• If chronic NOECs are available from three species representing three trophic levels (i.e. fish, Daphnia and algae), a factor of 10 is applied to the lowest NOEC. If there is convincing evidence that the most sensitive species for which acute toxicity data are available have been tested chronically, a factor of 10 may also be applied to the lowest NOEC from two species representing two trophic levels (i.e. fish and/or Daphnia and/or algae).

It should be noted that in the case of algae studies, which are actually multigenerational studies, it is generally accepted that a 72-hour (or longer) EC50 value may be considered as equivalent to a short-term result and that a 72-hour (or longer) EC10 or NOEC value can be considered as a long-term results.

Table 32 below presents the summary of derived TRVs for the Protection of Aquatic Species (PNECs). Appendix C presents the environmental reviews of the COPEC identified in the hydraulic fracturing fluids and includes further details on the endpoints selected and PNEC values calculated for each COPC.

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Table 32 Summary of derived TRVs for protection of aquatic species (PNECs)

CAS # Chemical Endpoint* E(L)C50 or NOEC (mg/L)

Assessment Factor

PNEC Aquatic (mg/L)**

Water-based stimulation fluid systems

7681-52-9 Sodium hypochlorite 48-hr EC50 (Daphnia)

0.04 1000 0.00004

64-19-7 Acetic acid Chronic Daphnia 23 50 0.46

10377-60-3 Magnesium nitrate ANZECC 2000 FRESHWATER QUALITY GUIDELINES 0.7

26172-55-4 5-chloro-2-methyl-2h-isothiazolol-3-one (Methylchloroisothiazolinone)

72-hr EC50 (algae) 0.027 1,000 0.000027

2682-20-4 2-methyl-2h-isothiazol- 3-one (Methylisothiazolinone)

72-hr EC50 (algae) 0.027 1,000 0.000027

14808-60-7 Silicon Dioxide (crystalline silica quartz)

NA. Not a PBT substance.

1310-73-2 Sodium hydroxide (caustic soda)

NA. Not a PBT substance.

91053-39-3 Diatomaceous earth, calcined NA. Not a PBT substance.

14464-46-1 Cristobalite NA. Not a PBT substance.

Gel-based stimulation fluid systems

9000-30-0 Guar gum 48-hr EC50 (Daphnia)

42 1,000 0.042

9025-56-3 Hemicellulase Enzyme 96-hr LC50 (fish) 330 1,000 0.33

26038-87-9 MEA borate 72-hr EC50 (algae) 13 1000 0.0130

7772-98-7 Sodium thiosulfate 96-hr EC50 (algae) 100 1000 0.100

10043-01-3 Aluminium Sulfate Chronic fish 0.06 1 0.060

9012-54-8 Cellulase Enzyme 96-hr LC50 (fish) 330 1,000 0.330

151-21-3 Sodium Lauryl Sulfate Chronic Daphnia 0.88 10 0.088

9005-64-5 Sorbitan, monododecanoate, poly(oxy-1,2-diethanediyl)

Acute Algae 100 1000 0.100

63-42-3 Lactose 96-hr LC50 (fish) (ECOSAR)

81,045 1000 81

7727-54-0 Diammonium peroxidisulphate 96-hr LC50 (fish) 76 1000 0.076

61789-40-0 1-Propanaminium, 3-amino-n-(carboxy methyl)-n,n-dimethyl-n-coco alkyl

Chronic Daphnia 0.932 50 0.019

111-30-8 Glutaraldehyde 21 day NOEC (Daphnia) 2.1 100 0.021

56-81-5 Glycerol 96-h EC50 (algae) 77,712 1000 78

7631-90-5 Sodium bisulfite 21 day NOEC (Daphnia)

13 50 0.26

9003047 Sodium polyacrylate 21 day NOEC (Daphnia) 5.6 100 0.06

7447-40-7 Potassium chloride 72-hr EC50 (algae) 100 1000 0.100

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CAS # Chemical Endpoint* E(L)C50 or NOEC (mg/L)

Assessment Factor

PNEC Aquatic (mg/L)**

1332-77-0 Potassium borate Canadian Water Quality Guidelines for the Protection of Aquatic Life Long–term Exposure to Boron 1.5

77-92-9 Citric Acid 24-h EC50 (Daphnia) 85 1000 0.085

68916-18-7 Coffee Extract 96-hour LC50 (Fish) 87 1000 0.087

81741-28-8 Tributyl tetradecyl phosphonium chloride

48-hr EC50 (Daphnia)

0.025 1000 0.000025

497-19-8 Sodium Carbonate

48-hr EC50 (Daphnia)

200 1000 0.2

9004-32-4 Sodium Carboxymethyl Cellulose

96-hour EC50 (algae)

500 1000 0.5

7664-93-9 Sulphuric Acid Chronic Fish 0.13 50 0.0026

7786-30-3 Magnesium chloride 72-hr EC50 (algae) 100 1000 0.1

10043-52-4 Calcium chloride Chronic Daphnia 160 50 3.2

9000-70-8 Gelatins NA. Not a PBT substance.

1310-58-3 Potassium Hydroxide* NA. Not a PBT substance.

144-55-8 Sodium Bicarbonate* NA. Not a PBT substance.

68308-35-8 Shellac, ammonium salt NA. Not a PBT substance.

7647-01-0 Hydrochloric Acid* NA. Not a PBT substance.

9050-36-6 Maltodextrin NA. Not a PBT substance.

14808-60-7 Silica NA. Not a PBT substance.

7647-14-5 Sodium chloride NA. Not a PBT substance.

14807-96-6 Talc, Magnesium Silicate NA. Not a PBT substance.

7631-86-9 Non-crystalline silica NA. Not a PBT substance.

NA – data not available or not applicable *PNEC not calculated due to the pH properties of the COPC and the buffer capacity of the aquatic ecosystem. ** refer to Appendix C for further information on the endpoints selected and PNEC values for each COPC.

5.4 Quantification of Exposure 5.4.1 Exposure Pathways

As discussed in Section 5.2, the key environmental receptors (and exposures that are considered significant) that may be exposed to the COPEC identified on and off the site were aquatic invertebrates and fish.

5.4.2 Exposure Point Concentrations

Similar to the human health risk assessment, the exposure point concentrations for the environmental risk assessment was based on a theoretical data set (assuming 20% and 60% mass recovery in flowback water) and an empirical dataset (based on the results of laboratory analysis of flowback water from existing operations). The theoretical COPECs are presented in Table 11 to Table 16. The empirical COPEC identified within the flow back water is presented in Table 33 below.

Table 33 Identification of empirical COPEC in flowback water on-site

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Analyte Detected in Flowback Water

Max Concentration Reported in 2014 (mg/L)

Adopted Screening Level Guideline (mg/L) Selected as COPC?

benzene 0.006 0.95 ANZECC No

toluene 0.013 0.18 ANZECC No

ethylbenzene 0.002 0.08 ANZECC No

xylenes 0.0081 0.2 ANZECC No

TPH C6-C10 0.5 0.18* ANZECC Yes

TPH C10-C34 0.67 0.7 ANZECC No

aluminium 0.089 0.055 ANZECC Yes

antimony 0.0013 0.009 ANZECC No

arsenic 0.0022 0.013 ANZECC No

barium 7.1 0.004 USEPA Yes

boron 2 0.37 ANZECC Yes

cobalt 0.0014 0.0014 ANZECC No

copper 0.0044 0.0014 ANZECC Yes

iron 4.9 0.3 ANZECC Yes

lead 0.00052 0.0034 ANZECC No

magnesium 14 82 USEPA No

manganese 0.093 1.9 ANZECC No

mercury 0.0003 0.0006 ANZECC Yes

molybdenum 0.0025 0.034 ANZECC No

nickel 0.0044 0.011 ANZECC No

selenium 0.0036 0.005 ANZECC No

vanadium 0.0005 0.006 ANZECC No

zinc 0.0057 0.008 ANZECC No *No specific guideline available for TPH C6-C10, used toluene as surrogate Shaded cells indicate COPEC assessed as part of this ERA. -- No guideline available ANZECC 2000 Freshwater Quality Guidelines ; USEPA Region 3 Biological Technical Assistance Group Freshwater Screening Benchmarks.

5.5 Screening Level Environmental Risk Characterisation Risk characterisation is the process of quantifying and characterising risk using the selected measurement endpoints or lines of evidence. The NEPC (2013) and USEPA (1997) have recommended protection goals for interpreting the risks associated with individual hazard quotients (HQ) and toxicity test results.

The use of HQs has been common practice in human health risk assessments and has been carried over and used in most screening level ERAs. In this screening level ERA for aquatic receptors, calculation for HQs was used in assessing the risk of COPECs where limited species specific toxicity data exists.

5.5.1 Estimation of Risk

The results of the exposure assessment (EPCs) are compared to TRVs (or PNEC aquatic) to estimate the potential for adverse environmental effects. When exposure is greater than TRVs there is a

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potential for adverse impacts. To assess potential adverse environmental effects HQs were calculated. Hazard quotient calculations were calculated using the derived TRVs. HQs were calculated as follows:

HQ aquatic = EPC

TRV (or PNEC aquatic)

Where:

HQaquatic = Hazard Quotient EPC = COPEC exposure point concentration in surface water (mg/L) TRV = Concentration based TRV (or PNEC aquatic) (mg/L)

To assess the overall potential for adverse environmental effects posed by simultaneous exposure to multiple chemicals, the hazard quotients for each chemical and exposure pathway have been summed. The resulting sum is referred to as the hazard index (HI).

The risk classification system used to qualify the potential for environmental risk based on HI results was as follows:

• HI less or equal to 1 indicates acceptable low or extremely low risk;

• HI greater than 1 indicates potential risk or adverse effects and further evaluation is required to refine the calculation of potential risk to environmental receptors.

This HI system was considered appropriate given the conservative approach to estimating environmental exposure levels using the maximum measured COPEC concentrations and provide a tool by which the potential for impacts in surface water can be assessed. All hazard quotient and hazard index calculations are presented in Appendix E.

5.5.2 Summary of Risk

A summary of the cumulative hazard indexes for both the theoretical and empirical scenarios for the identified receptor group (aquatic invertebrates and fish) are presented in Table 34 to Table 39. It is noted that a conservative approach has been adopted to estimate potential “worst case scenario” environmental risk. This worst case scenario is based on a significant spill or release event directly to an adjacent surface water body, with no operational or spill management controls. The calculations presented below also do not take into account the significant dilution that is expected to occur where flow back water is discharged to a surface water body in the event of a significant spill or leak. In addition, processes such as sorption and biodegradation have not been considered.

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Table 34 Summary of calculated HQ for aquatic risk – 20% and 60% mass return (theoretical) and empirical data for hydraulic fracturing fluid

CAS Chemical Endpoint E(L)C50 or NOEC

Assessment Factor

PNEC Aquatic

EPC Calculated HQ

20% Mass Return

60% Mass return

20% Mass Return

60% Mass return

water-based stimulation fluid 64-19-7 Acetic acid Chronic Daphnia 23 50 0.46 58 175 127 380

10377-60-3 Magnesium nitrate ANZECC 2000 FRESHWATER QUALITY GUIDELINES 0.7 3.48 10 5 15

26172-55-4 5-chloro-2-methyl-2h-isothiazolol-3-one(Methylchloroisothiazolinone)

72-hr EC50 (algae) 0.027 1,000 0.000027 0.70 2.1 25926 77778

2682-20-4 2-methyl-2h-isothiazol- 3-one(Methylisothiazolinone) 72-hr EC50 (algae) 0.027 1,000 0.000027 0.20 0.7 7407 25926

Total HI 33465 104098 COPC identified in flowback water analysis from current operations

-- TPH C6-C10 ANZECC 2000 FRESHWATER QUALITY GUIDELINES* 0.18* 0.5 0.5 2.8 2.8

7429-90-5 aluminium ANZECC 2000 FRESHWATER QUALITY GUIDELINES 0.055 0.089 0.089 1.6 1.6

7440-39-3 barium USEPA Region 3 Biological Technical Assistance Group Freshwater Screening Benchmarks 2006 0.004 7.1 7.1 1775 1775

7440-42-8 boron ANZECC 2000 FRESHWATER QUALITY GUIDELINES 0.37 2 2 5.4 5.4

7440-50-8 copper ANZECC 2000 FRESHWATER QUALITY GUIDELINES 0.0014 0.0044 0.0044 3.1 3.1

7439-89-6 iron ANZECC 2000 FRESHWATER QUALITY GUIDELINES 0.3 4.9 4.9 16.3 16.3

7439-97-6 mercury ANZECC 2000 FRESHWATER QUALITY GUIDELINES 0.0006 0.0003 0.0003 0.5 0.5

Total HI 1805 1805 Notes: *Used Toluene as surrogate The following can be noted from the table above:

• The calculated hazard index results for the theoretical and empirical worst case exposure scenarios show all COPECs exceeding the acceptable riskthreshold of 1.0, indicating potentially unacceptable risks to the receiving aquatic environment.

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Table 35 Summary of calculated HI for aquatic risk – 20% and 60% mass return (theoretical) and empirical data for hydraulic fracturing fluid


Assessment Factor

PNEC Aquatic

EPC Calculated HQ

20% Mass Return

60% Mass return

20% Mass Return

60% Mass return

gel-based stimulation fluid9000-30-0 Guar gum 48-hr EC50 (Daphnia) 42 1,000 0.042 242 726 5762 17296

26038-87-9 MEA borate 72-hr EC50 (algae) 13 1000 0.0130 122 367 9385 28259

9012-54-8 Cellulase Enzyme 96-hr LC50 (fish) 330 1,000 0.330 4 13 12 41

63-42-3 Lactose 96-hr LC50 (fish) (ECOSAR) 81,045 1000 81 96 289 1 4

7631-90-5 Sodium bisulfite 21 day NOEC (Daphnia) 13 50 0.26 2 7 8 27

9003047 Sodium polyacrylate 21 day NOEC (Daphnia) 5.6 100 0.06 9 28 161 507

7447-40-7 Potassium chloride 72-hr EC50 (algae) 100 1000 0.100 3987 11960 39867 119602

77-92-9 Citric Acid 24-h EC50 (Daphnia) 85 1000 0.085 69 207 812 2434

68916-18-7 Coffee Extract 96-hour LC50 (Fish) 87 1000 0.087 9 28 106 319

64-19-7 Acetic acid Chronic Daphnia 23 50 0.46 104 311 225 676

Total HI 581192 1743724

COPC identified in flowback water analysis from current operations








Total HI 1805 1805 Notes: *Used Toluene as surrogate

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• The calculated hazard index results for the theoretical and empirical worst case exposure scenarios show all COPECs exceeding the acceptable risk threshold of 1.0,indicating potentially unacceptable risks to the receiving aquatic environment.

Table 36 Summary of calculated HI for aquatic risk – 20% and 60% mass return (theoretical) and empirical data for hydraulic fracturing fluid


Assessment Factor

PNEC Aquatic

EPC Calculated HQ 20% Mass Return

60% Mass return

20% Mass Return

60% Mass return

gel-based stimulation fluid

9000-30-0 Guar gum 48-hr EC50 (Daphnia) 42 1,000 0.042 679 2037 16167 48506

9025-56-3 Hemicellulase Enzyme 96-hr LC50 (fish) 330 1,000 0.33 9 28 28 83

26038-87-9 MEA borate 72-hr EC50 (algae) 13 1000 0.0130 210 630 16154 48479

63-42-3 Lactose 96-hr LC50 (fish) (ECOSAR) 81,045 1000 81 120 361 1 4

61789-40-0

1-Propanaminium, 3-amino-n-(carboxymethyl)-n,n-dimethyl-n-coco alkyl Chronic Daphnia 0.932 50 0.019 570 1711 30579 91782

56-81-5 Glycerol 96-h EC50 (algae) 77,712 1000 77.712 79 236 1 3

64-19-7 Acetic acid Chronic Daphnia 23 50 0.46 167 500 362 1087

7631-90-5 Sodium bisulfite 21 day NOEC (Daphnia) 13 50 0.26 3 8 12 31

9003047 Sodium polyacrylate 21 day NOEC (Daphnia) 5.6 100 0.06 13 39 232 702

77-92-9 Citric Acid 24-h EC50 (Daphnia) 85 1000 0.085 76 227 894 2667

7447-40-7 Potassium chloride 72-hr EC50 (algae) 100 1000 0.100 3971 11914 39710 119138

68916-18-7 Coffee Extract 96-hour LC50 (Fish) 87 1000 0.087 16 47 180 539

81741-28-8 Tributyl tetradecyl phosphonium chloride 48-hr EC50 (Daphnia) 0.025 1000 0.000025 24 73 967249 2901748

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CAS Chemical Endpoint E(L)C50

Assessme

PNEC

EPC Calculated HQ

Total HI 1071569 3214770










The following can be noted from the table above: • The calculated hazard index results for the theoretical and empirical worst case exposure scenarios show COPECs exceeding the acceptable risk

threshold of 1.0, indicating potentially unacceptable risks to the receiving aquatic environment.

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Table 37 Summary of Calculated HI for Aquatic Risk – 20% and 60% Mass Return (Theoretical) and Empirical Data for Hydraulic Fracturing Fluid


Assessment Factor

PNEC Aquatic

EPC Calculated HQ

20% Mass Return

60% Mass return

20% Mass Return

60% Mass return


9025-56-3 Hemicellulase Enzyme 96-hr LC50 (fish) 330 1,000 0.33 0.200 0.599 1 2

10043-01-3 Aluminium Sulfate Chronic fish 0.06 1 0.060 132 396 2200 6603

151-21-3 Sodium Lauryl Sulfate Chronic Daphnia 0.88 10 0.088 21 62 239 708

9005-64-5

Sorbitan, monododecanoate, poly(oxy-1,2-diethanediyl) Acute Algae 100 1000 0.100 38 113 380 1133

9004-32-4

Sodium Carboxymethyl Cellulose 96-hour EC50 (algae) 500 1000 0.5 1001 3003 2002 6007

7664-93-9 Sulfuric Acid Chronic Fish 0.13 50 0.0026 33 99 12678 38035

Total HI 17500 52487




7440-39-3 barium USEPA Region 3 Biological Technical Assistance Group Freshwater Screening Benchmarks 2006

0.004 7.1 7.1 1775 1775





Total HI 1805 1805

Notes: *Used Toluene as surrogate

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• The calculated hazard index results for the theoretical and empirical worst case exposure scenarios show all COPECs exceeding the acceptable riskthreshold of 1.0, indicating potentially unacceptable risks to the receiving aquatic environment.



Assessment Factor

PNEC Aquatic

EPC Calculated HQ

20% Mass Return

60% Mass return

20% Mass Return

60% Mass return


9000-30-0 Guar gum 48-hr EC50 (Daphnia) 42 1,000 0.042 473 1420 11262 33821

9025-56-3 Hemicellulase Enzyme 96-hr LC50 (fish) 330 1,000 0.33 23.6994218 71 72 215

7727-54-0 Diammonium peroxidisulphate 96-hr LC50 (fish) 76 1000 0.076 71 214 934 2816

111-30-8 Glutaraldehyde 21 day NOEC (Daphnia) 2.1 100 0.021 31 94 1476 4469

56-81-5 Glycerol 96-h EC50 (algae) 77,712 1000 77.712 59 178 1 2

1332-77-0 Potassium borate Canadian Water Quality Guidelines for the Protection of Aquatic Life 1.5 182 545

Total HI 13866 41687




7440-39-3 barium USEPA Region 3 Biological Technical Assistance Group Freshwater Screening Benchmarks 2006

0.004 7.1 7.1 1775 1775






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Assessment Factor

PNEC Aquatic

EPC Calculated HQ

20% Mass Return

60% Mass return

20% Mass Return

60% Mass return


7681-52-9 Sodium hypochlorite 48-hr EC50 (Daphnia) 0.04 1,000 0.00004 33 98 815858 2447575

64-19-7 Acetic acid Chronic Daphnia 23 50 0.460 62 187 136 407 Total HI 815994 2447982












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5.6 Direct Toxicity Assessments In accordance with approval requirements to assess the toxicity of the mixture, APLNG engaged consultant Hydrobiology to develop an ecotoxicity testing program to assess the incremental toxicity of representative hydraulic fracturing fluids, in the context of the natural ecotoxicity of CSG groundwater to surface freshwater organisms. The Hydrobiology report “Freshwater Ecotoxicity of Coal Seam Gas Hydraulic Stimulation Fluids” June 2016 is presented in Appendix B. A brief summary of the report is provided below.

Direct toxicity assessments were conducted to assess the ecotoxicity of the hydraulic stimulation fluids in the context of CSG waters (coal seam water pre-stimulation) and flow back waters (coal seam water post stimulation) from within the Surat Basin, as such, ecotoxicity testing of the hydraulic stimulation fluids was performed using whole mixtures rather than the individual components. The program of works consisted of three phases:

Phase 1 – Background ecotoxicity of CSG water. The aim was to determine the background ecotoxicity of representative CSG water, collected from a non-stimulated well (RC-PW06J) within the Reedy Creek tenement.

Phase 2 – Ecotoxicity of representative hydraulic stimulation fluids. The aim was to assess the response of freshwater species to two hydraulic stimulation fluid types (cross-linked fluid RAM24 and nitrogen foam cross-linked fluid RAM23) mixed with source water from the Talinga water treatment facility.

Phase 3 – Ecotoxicity of flowback waters. The aim was to determine the hazard potential of flowback waters in comparison with pre-stimulated CSG waters (Phase 1) and a representative hydraulic stimulation fluid (Phase 2). Flowback waters from the Ramyard tenement were selected (RAM23 and RAM24), and stimulated with fluids tested in Phase 2, and a late stage flowback from the Horsecreek tenement (HCK16) was also tested, stimulated using similar cross-linked mixture compared with the RAM24 stimulation fluid.

The direct toxicity testing was conducted in accordance with standard methods based on OECD and USEPA protocols and consistent with ANZECC/ARMCANZ (2000) guidelines for direct toxicity assessment. The summary of the test species used are presented in Table 39 below: Table 40 Test Organisms Used for Direct Toxicity Assessment

Test Organism Test Duration Test Type Testing Facility

Raphidocelis subcapitata (Freshwater alga)

72-hr (chronic) Algal growth inhibition/ Cell division test

ESA

Landoltia punctata (Duckweed) 96-hr (chronic) Plant growth Inhibition CQU

Caridina nilotica (Freshwater shrimp) 96-hr (acute) Juvenile Survival CQU

Ceriodaphnia cf. dubia (Freshwater daphnid)

48-hr (acute) Survival ESA


168-hr (chronic)

Reproductive impairment (3-brood)

ESA

Hydra viridissima (Freshwater hydra) 96-hr (chronic) Population growth test ESA

Chironomus tepperi (Freshwater midge)


Melanotaenia splendida (Rainbowfish) 96-hr (acute) Imbalance ESA Source: Hydrobiology (2016); ESA – Ecotox Services Australia; CQU – Central Queensland University The summary of the results from the three phases is presented in Table 40. Trigger values (TVs) were calculated using the species sensitivity distribution method, following the ANZECC (2000) methodology.

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Table 41 Summary of Hydrobiology Ecotoxicity Results Including IC10 (expressed in %) for Each Species and Trigger Value for 95% Species Protection

Test

Sol

utio

n

Alg

al G

row

th:

R. s

ubca

pita

ta

Duc

kwee

d G

row

th:

L. p

unct

ata

Juve

nile

Shr

imp

Surv

ival

: C

. nilo

tica

Dap

hnia

Sur

viva

l:

C. d

ubia

Dap

hnia

Rep

rodu

ctiv

e Im

pairm

ent :

C

. dub

ia

Hyd

ra P

opul

atio

n G

row

th:

H. v

iridi

ssim

a

Mid

ge S

urvi

val :

C

. tep

peri

Fish

Lar

vae

Imba

lanc

e:

M. s

plen

dida

Ecot

oxic

ity T

V (%

) Fo

r 95%

Spe

cies

Pr

otec

tion

CSG Water RC-PW006J 0.9* 32 29 8 10 4 100 27 1.3 CL:0.20-15.30

Stimulation Fluid

RAM24 0.04 1.2 0.6 0.1 0.1 0.1 0.2 0.6 0.034 CL:0.015-0.220

RAM23 0.005 0.8 0.2 0.01 0.04 0.06 0.02 0.05 0.005 CL:0.001-0.026

Flowback Water

RAM24 (27%)

2.9 26 15 14 14 0.8 100 32 1.1 CL:0.19-11.49

RAM23

(160%)

0.8 36 29 8 8 8 100 51 1.4 CL:0.18-15.27

HCK16

(1,605%)

2.9 26 52 16 15 6 100 70 2.7 CL:0.86-20.14

Source: Hydrobiology (2016) Shaded cells indicate species most sensitive to the test fluid. * Indicate tests for which IC10 values were not provided in the ecotoxicology laboratory reports due to low confidence limits The trigger value (TV) is the percent of test solution based on calculated SSDs using IC10 data converted to chronic ecotoxicity (Refer to Hydrobiology (2016) for more detail). CL = Confidence Limits.

As indicated in Table 40, the results indicate similar toxicity between the two Ramyard flowback waters (RAM23 and RAM24). Flowback from HCK16, collected at a later stage flowback return volume of 1605%, had a slightly lower ecotoxicity than the Ramyard flowback waters (that were collected at earlier stages of flowback return volumes). The flowback water samples were comparable with TVs observed for the background CSG water, despite the much higher toxicity for the stimulation fluid. This indicates that the hazard from flowback waters is not increased above the non-stimulated CSG waters.

Based upon the available data, it can be concluded that significant dilution, sorption and biodegradation processes do occur in the coal seam, as the direct toxicity assessment results clearly demonstrate that the flowback water is of similar toxicity to the background CSG water to the species tested. Direct contact of stimulation fluids to the species tested are highly unlikely due to operational controls and management measures routinely implemented by Origin which effectively minimises the risk of accidental spills and releases of stimulation fluids.

5.7 Interpretation of Environmental Significance The estimated environmental risks have been qualitatively evaluated via a hazard index approach to determine their environmental significance for the CSG operations evaluated in this assessment. The HQ results show all COPECs from the theoretical data set exceed the acceptable risk threshold of 1.0 for aquatic receptors.

It is noted that this estimated potential risk is based on a significant spill or release event directly to an adjacent surface water body. The closest surface water body to a CSG pad is 46.8 m (“Durham Ranch well 101”) in Spring Gully. The calculations presented above do not take into account the significant dilution that is expected to occur where flow back water is discharged to a surface water body in the

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event of a significant spill or leak. In addition, processes such as sorption and biodegradation have not been considered.

Direct toxicity assessment results further confirm that significant dilution, sorption and biodegradation processes do occur in the coal seam, as the assessment results clearly demonstrate that the flowback water is of similar toxicity to the background CSG water to the species tested.

During normal operation procedures there are no discharges to adjacent surface water bodies. Furthermore, the lack of a robust aquatic toxicological database resulted in aquatic screening values for the theoretical exposure scenario COPEC to be highly conservative, which is expected to significantly overestimate the actual risk.

Notwithstanding this conservative approach to estimating environmental exposure levels, risk management measures are routinely implemented by Origin which effectively minimise the risk of accidental spills and releases of flowback fluid. These include:

• EA conditions that preclude the construction of well pads within 100 m of a watercourse of water body (except for the Spring Gully tenement);

• Implementation of spill containment procedures during operations to prevent migration of and exposure to chemicals;

• Routine holding tank inspections to check for leakage of flow back fluid;

• Freeboard buffer included above high fluid level automatic pump shut-off system, in the event of heavy rainfall;

• Locked perimeter fencing with warning signage.

Based on the implementation of a range of risk management measures by Origin, accidental releases of flowback fluid are considered to be low. No such events have occurred during operations conducted to date, supporting the unlikely nature of these events.

5.8 Conclusions The evaluation of potential risks to the environment associated with the use of chemicals in well simulation activities conducted by Origin within the project area has involved the assessment of potential exposures to compounds used or formed in the simulation activities. Based on the operational controls, security and management practices implemented by Origin, the design of the holding tanks and groundwater fate and transport modelling, the only potentially complete exposure pathway was from the accidental release of flowback water from the holding tank to adjacent aquatic environments.

On the basis of the assessment undertaken with consideration of the uncertainties identified in Section 7, the following can be concluded in relation to potential exposures to flowback water from well simulation activities:

• Risks to the environment are considered to be negligible or low. While potential impacts to aquatic receptors could occur if releases of flowback water reach adjacent surface water bodies (closest water body is approximately 46.8 m from CSG well “Durham Ranch well 101”), the likelihood that any of these chemicals may be discharged to an environment where any level of exposure may occur is considered low, due to the implementation of existing operational management measures. The identified level of risk is supported by review of historic and existing operations where no accidental releases of flowback water from the holding tanks have occurred.

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6.0 Non-Chemical Risks Assessment

6.1 Noise and Vibration Noise from the APLNG petroleum activities are regulated by Schedule E – Environmental Nuisance, common to the APLNG Environmental Authorities issued by the Department of Environment and Heritage Protection.

Schedule E stipulates that noise modelling must be undertaken prior to conducting petroleum activities that will result in short-term1, medium-term2 or long-term3 noise events that are likely to impact on a noise sensitive receptor. The predicted noise emissions at the sensitive receptor are to be assessed against the noise levels provided in Schedule E, Table 1. The Schedule E, Table 1 noise levels are provided in Table 42 below. Table 42 Schedule E, Table 1 noise levels as per the APLNG Environmental Authorities

Time Periods Relevant Fields Metric

Noise Event

Short Term Medium Term Long Term

6 am – 7 am RAM LAeq, adj, 15 min 40 dBA 38 dBA 35 dBA

7 am - 6 pm All LAeq, adj, 15 min 45 dBA 43 dBA 40 dBA

6 pm - 10 pm All LAeq, adj, 15 min 40 dBA 38 dBA 35 dBA

10 pm – 6 am RAM LAeq, adj, 15 min 28 dBA 28 dBA 28 dBA

RAM, SG Max LpA, 15 min 55 dBA 55 dBA 55 dBA

Noise from drilling activities undertaken from 10pm – 7am

COM, CON, SG, WAL

LAeq, adj, 15 min 30 dBA (measured indoors at any sensitive receiver)

Noise from fixed plant in gas fields undertaken from 10pm – 7am

COM, CON, SG, WAL

LAeq, adj, 15 min 28 dBA (measured indoors at any sensitive receiver)

Noise levels are taken to be measured noise levels outside a sensitive receptor unless stated otherwise. Note 1: Combabula (COM), Condabri (CON), Ramyard and Woleebee (RAM), Spring Gully (SG), and Walloons (WAL). Note 2: Noise limit does not differ between short, medium and long term noise events.

Where the Schedule E, Table 1 noise levels cannot be met, the Environmental Authority allows for alternative arrangements to be negotiated. The arrangement allows the petroleum activity to be exempt from the noise levels in Schedule E, Table 1 for the duration of the arrangement. Short term event is a noise exposure, when perceived at a sensitive receptor, persists for an aggregated period not greater than eight (8) hours and does not re-occur for a period of at least seven (7) days. Re-occurrence is deemed to apply where a noise of comparable level is observed at the same receptor location for a period of one (1) hour or more, even if it originates from a different source or source location. 2 Medium-term noise event is a noise exposure, when perceived at a sensitive receptor, persists for an aggregated period not greater than five (5) days and does not reoccur for a period of at least four (4) weeks. Re-occurrence is deemed to apply where a noise of comparable level is observed at the same receptor location for a period of one (1) hour or more, even if it originates from a different source or source location. 3 Long-term noise is a noise exposure, when perceived at a sensitive receptor, persists for an aggregated period of greater than five (5) days, even when there are respite periods when the noise is inaudible within those five (5) days. In accordance with Schedule E conditions, APLNG engaged acoustic consultant SLR Consulting Pty Ltd (SLR) to assess noise emissions from hydraulic fracturing activities. The assessment consisted of on-site measurements during hydraulic fracturing trials to determine source sound power levels (SWL) as well as noise modelling using a flat ground model to determine offset distances to meet the Schedule E, Table 1 noise levels.

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The main sources of noise identified during the hydraulic fracturing trials are show in Table 43 below. Table 43 Primary noise sources associated with gel, water and nitrogen gas hydraulic fracturing

Noise Source Gel Fluid Systems Water Fluid Systems Nitrogen Gas Fluid Systems

Blender X X X

High Pressure Pump X X X

Acid Pump X

Engine X

Hydration unit X

Nitrogen unit X

Nitrogen unit with vapouriser X

The results of the SLR hydraulic fracturing noise survey are summarised below (SLR, 2015).

• The total SWL for hydraulic fracturing activities ranged from 121 - 124 dBA.

• The noise assessment showed that noise emissions varied depending on the type of fracture conducted (water > gel > nitrogen gas) and increased at higher fracturing rates (measured as barrels (bbl) per minute). The modelling predicted that under neutral weather conditions, noise emissions achieve 35 dBA LAeq, adj, 15 min at an offset distance of 1.7 to 2.5 km from the hydraulic fracturing well site.

Depending on the location and nature of the activities, there is potential for hydraulic fracturing to have noise impacts on sensitive receptors within the APLNG operational area. However, noise emissions from hydraulic fracturing are of a relatively short duration, occurring at a given well site on a continuous basis for only a number of weeks at a time. While it is noted that some receptors may experience extended exposure due to noise emissions from hydraulic fracturing at multiple well sites, the noise emissions are not likely to contribute to long-term background noise creep and therefore are unlikely to have a significant impact on acoustic amenity.

Noise impacts to sensitive receptors from hydraulic fracturing are assessed on a case-by-case basis and managed in accordance with the Environmental Authority requirements.

6.2 Radiological Exposure In some hydraulic fracturing operations, low concentrations of radioactive tracers are injected into the coal seam during the slurry volume injection stage. These tracers comprise manufactured insoluble ceramic beads which have been imbued with a low concentration of radionuclides (with short half-lives, less than 84 days); the tracers are manufactured to be the same grainsize and density as the proppant that is being used for the hydraulic fracturing operation. Hence the tracers travel with proppant material into the target coal seam.

The tracer beads are used to measure the vertical extent of the hydraulic fracturing which occurred in the well, a measurement recorded at the conclusion of the operation (see Section 2.4.8.2).

In order to assess the potential risk to human health from the use of radioactive tracer beads as part of the hydraulic fracturing activities, a Persistence, Bioaccumulative and Toxicity (PBT) environmental health assessment (EHA) was conducted As a part of the EHA, potential migration pathways and receptors were identified and exposure point concentrations were considered to conduct the risk characterisation, calculation, and uncertainty analyses.

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Based on the EHA, it is considered that the use (and potential containment of residues in mix and cover pits) of radioactive tracer beads as part of the hydraulic fracturing activities, and management of flow back material in accordance with the manufacturer specifications, are considered sufficient for the management of low and acceptable human health impacts.

In addition, based on published half-life data of at most 83.8 days (range 60.2 to 83.8), the radioactive tracer will not be persistent in the environment and will below analysis detection limit in a short time period.

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7.0 Uncertainty Assessment In general, the uncertainties and limitations of the human health and environmental risk assessment can be classified into the following categories:

• Sampling and analysis;

• Receptor exposure assessment; and

• Toxicological assessment.

The risk assessment process, following both Australian and international guidance, provides a systematic means for organising, analysing, and presenting information on the nature and magnitude of risks to public health posed by chemical exposures. Despite the advanced state of the current risk assessment methodology, uncertainties and limitations are inherent in the risk assessment process. The uncertainties associated with each of these categories are discussed in the sections above.

7.1 Sampling and Analysis Uncertainties Variability in environmental chemistry sampling and analysis error can stem from the sampling and analysis procedures, and from the heterogeneity of the matrix being sampled. In relation to the assessment presented in this report, a number of uncertainties exist in the assessment of potential exposures to COPC based on empirical data. Limited empirical data is available for flow back water from existing operations, and from the use of the range of stimulation fluids proposed. In addition the concentrations of COPC in regional groundwater (within the target coal seam) are not known. Hence assuming that all of the detected compounds (inorganic and organic) are associated with the well stimulation activities is highly conservative and may not be representative of impacts that may be only associated with these activities. It is expected that once additional data is available on flow back water quality (and regional water quality) that these potential risk issues are further reviewed.

7.2 Exposure Uncertainties Risk assessments require the adoption of several assumptions in order to assess potential human exposure. This risk assessment includes assumptions about general characteristics and patterns of human exposure relevant to the receptor groups. These assumptions are conservative and developed to provide an estimate of maximum possible exposures rather than the actual exposures. This approach is expected to overestimate the risks.

More specifically, the presence and concentrations of COPC assumed in the calculations are based on a worst-case assumption that the COPC present in stimulation fluids do not degrade or sorb significantly in the sub-surface, and that these chemicals may all be present in the water to which trespassers, aquatic receptors and terrestrial species are exposed. In addition it is assumed that a range of stimulation fluids are used in the same area of operation at the same time.

7.3 Toxicity Uncertainties In general, the available scientific information is insufficient to provide a thorough understanding of all of the potential toxic properties of chemicals to which humans may be exposed. It is necessary, therefore, to extrapolate these properties from data obtained under other conditions of exposure which generally involve experimental laboratory animals.

Although there may be interspecies differences in chemical absorption, metabolism, excretion and toxic response, there may also be uncertainties concerning the relevance of animal studies using exposure routes that differ from human exposure routes. In addition, the frequent necessity to extrapolate results of short term or subchronic animal studies to humans exposed over a lifetime has inherent uncertainty. In order to adjust for these uncertainties, published toxicity values generally incorporate safety factors that may vary from 10 to 1000. The uncertainties inherent in the toxicological values adopted are considered likely to result in an overestimation of actual risk.

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8.0 Conclusions The potential risks to human health and the environment associated with hydraulic fracturing in the project area was undertaken in accordance with enHealth, NEPM and ANZECC guidance, with reference to peer-reviewed international guidance where relevant.

Detailed operational procedures have been developed that are designed to contain the hydraulic fracturing fluids within the coal sequences, such that groundwater utilised for the purpose of extraction (for any beneficial use), or springs is not impacted by hydraulic fracturing chemicals.

Contaminant fate and transport modelling indicated that there will be less than 10m migration of residual hydraulic fracturing chemicals in the coal seams away from the induced fractures in 1000 years.

The risk of chemical exposure to workers involved in the operation of hydraulic fracturing activities (including the transportation of chemicals) was not quantitatively evaluated as this risk is addressed through the implementation of appropriate occupational health and safety procedures and management plans.

Potential exposures to hydraulic fracturing chemicals were therefore assessed to be limited to the above ground storage and handling of flow back water. Management of CSG water involves temporary storage of flow back water in above ground fluid holding tanks, after which the fluid will be transported to a water treatment facility. Exposure point concentrations were developed for each of the hydraulic fracturing fluid systems using a combination of theoretical calculations (where it was assumed that between 20% and 60% of the mass of the chemicals injected into the well will be present in the flow back water) and empirical data obtained from laboratory analysis of flowback water from existing operations.

The toxicity of the chemicals used in the hydraulic fracturing process has been assessed for persistence, bioaccumulation and aquatic toxicity (PBT), and human health toxicity. The chemicals used in the hydraulic fracturing process do not contain BTEX or polycyclic aromatic hydrocarbons as additives. It is noted that none of the COPC identified for consideration in this HHRA (with the exception of sodium polyacrylate, CMIT, MIT sodium hypochlorite and TTPC) are persistent, bioaccumulative and toxic, hence there are no secondary pathways of concern (such as accumulation in crops and produce, and subsequent human consumption) that require quantification. Sodium polyacrylate is limited in biodegradability potential, however it is not bioaccumulative and essentially non-toxic to receptors and hence secondary pathways of concern are not complete. While sodium hypochlorite, MIT and CMIT meets the screening criteria for toxicity, qualified by their acute toxicity capacity, adverse chronic outcomes are not evident based on their reactivity and lack of persistence and bioaccumulation in the environment. Limited information is available for TTPC (i.e no persistence or biodegradation information), however the acute toxicological data available suggests that TTPC does meet the screening criteria for toxicity. Primary adverse health effects associated with the use of TTPC (as a pure substance) are related to irritant and corrosive properties for the skin, eyes, nose and lungs. It is to be noted that Worker exposures of TTPC are addressed through the implementation of appropriate occupational health and safety procedures and management plans. Considering the significant dilution, sorption and biodegradation processes that occur in the coal seam, it is not expected that such properties of TTPC would be realised in the flow back water.

Based on the operational controls, security and management practices implemented by Origin, the design of the holding tanks and groundwater fate and transport modelling, the potentially complete exposure pathways identified and assessed in the risk assessment comprised the following:

• Incidental ingestion and dermal contact by trespassers at the flowback fluid holding tanks; and

• Potential releases of water to aquatic environments.

On the basis of the risk calculations taken, with consideration of the uncertainties identified, the following can be concluded in relation to potential exposures to flow back water from well stimulation activities:

• No unacceptable risks to trespassers were identified. Conservative risk scenarios assessed included regular access to the uncovered holding tanks, where swimming type activities were undertaken, with exposures to high theoretical concentrations of COPC in the flowback water.

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• Risks to the environment are considered to be negligible or low. This is further supported by Hydrobiology’s direct toxicity assessment results, which demonstrates that the flowback water is of similar toxicity to the background CSG water.

• The likelihood that any of these chemicals may be discharged to an environment where any level of exposure may occur is managed via the implementation of existing operational management measures consistent with API guidance and ‘Best Practice’ specifications for the design and implementation of all hydraulic fracturing operations that are conducted for the APLNG Project. The identified level of risk is supported by review of historic and existing operations where no accidental releases of flowback water from the holding tanks have occurred.

Effective operational controls and management implemented by Origin further minimises the potential for exposures. These operational controls include:

• EA conditions that preclude the construction of well pads within 100 m of a watercourse of water body (except Spring Gully);

• Implementation of spill containment procedures during operations to prevent migration of and exposure to chemicals, and if a spill was to occur, rectification measures would be taken immediately and notification to DEHP of any unauthorised releases will be made;

• Routine gathering network inspections and evaluation of production rate data;

• Routine holding tank inspections to check for leakage of flow back fluid;

• Freeboard buffer included above high fluid level automatic pump shut-off system, in the event of heavy rainfall;

• Fencing and signage around the flowback storage tanks

• Routine operational and security patrols to prevent trespassing

The summary of the results from the human health and environmental risk assessment and associated risk mitigation measures is presented in Table 44, below.

The operational controls will be routinely evaluated by Origin and modifications and revisions made, where necessary. These operational and management controls can be further supported by the following recommendations:

• Maintain compliance with Origin’s Stimulation Impact Monitoring Plan (Q-LNG01-15-MP-1124), which has been addressed to monitor the impact of hydraulic fracturing in the project area.

• Where possible, temporarily install pressure monitoring transducers in landholder bores installed with 1.5 km (1 order of magnitude greater than the estimated hydraulic fracturing radius of influence) of gas wells to be hydraulically fractured. These transducers could be used to monitor groundwater pressure the aquifers targeted by landholder bores throughout the hydraulic fracturing operation.

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Table 44 Results from Quantitative human health and environmental risk assessment


Hazard Causes and Consequences Risk Mitigation Measures Reason for carrying forward the potential hazard into the subsequent Quantitative Risk Assessment

Results of Quantitative Risk Assessment Recommended Mitigation to Address Residual Risk

Surf

ace

Env

ironm

ent The loss of

containment of chemicals used for hydraulic fracturing

Exposure of workers, residents or the environment to potentially hazardous hydraulic fracturing chemicals, resulting from loss of containment occurring: • Whilst in transit to site;

• During the mixing of hydraulic fracturing fluid on

site; or • (In diluted form) during the storage and transport

of well flowback fluid.

Origin implement a range of engineering and operational control measures to ensure the risk of hydraulic fracturing fluid spills are minimised during hydraulic fracturing operations, including during transport to and from the wellsite and during the flowback of hydraulic fracturing chemicals from the well. These control measures include:

• Adherence to the material storage and transport requirements as stipulated on the chemical Safety Data Sheets (SDS).

• Adherence to the Transport of Dangerous Goods by Road Regulations (for chemicals classified as a ‘Dangerous Goods’).

• Ensuring chemicals remain in their original containers and are not decanted into smaller containers which may not be fit for purpose.

• During hydraulic fracturing operations, the use of secondary containment beneath all pipework connections and equipment holding or pumping chemicals.

Using fit for purpose flowback fluid storage tanks. Conducting regular integrity checks of fluid storage tanks, during commissioning and use. Ensure adequate freeboard is maintained at all times.

The evaluation of the risk to workers involved in the operation of well stimulation activities (including transportation of the COPC to the site) is not considered warranted in the subsequent sections of this risk assessment, as it is addressed via the implementation of appropriate occupational health and safety procedures and management plans.

Further consideration is warranted regarding the risk of above ground exposure relating to the handling and storage of hydraulic fracturing chemicals and flowback water. This is addressed in Section 4.5.

Further assessment is warranted regarding the risk associated with the potential and actual concentrations of COPC in flow back water; and the presence of other COPC that may have been liberated during the hydraulic fracturing operations. This is addressed in Section 4.5.

Further assessment is warranted regarding the chemical and physical properties of the constituents used in hydraulic fracturing fluids that result in the potential for these chemicals to be present in flow back water and to be of concern in relation to potential acute or chronic risks. This is addressed in Section 4.5.

Exposures by workers involved in the operation of well stimulation activities have not been evaluated as their exposures are addressed through the implementation of appropriate occupational health and safety procedures and management plans.

The PBT assessment of the chemicals indicated that all of the COPCs (with the exception of sodium polyacrylate, CMIT, MIT sodium hypochlorite and TTPC) were not persistent, bioaccumulative and toxic in the environment. Sodium polyacrylate is limited in biodegradability potential, but not bioaccumulative and essentially non-toxic to receptors. While sodium hypochlorite, MIT and CMIT meets the screening criteria for toxicity, qualified by their acute toxicity capacity, adverse chronic outcomes are not evident based on their reactivity and lack of persistence and bioaccumulation in the environment. Limited information is available for TTPC (i.e no persistence or biodegradation information), however the acute toxicological data available suggests that TTPC does meet the screening criteria for toxicity. Primary adverse health effects associated with the use of TTPC (as a pure substance) are related to irritant and corrosive properties for the skin, eyes, nose and lungs. . Considering the significant dilution, sorption and biodegradation processes that occur in the coal seam, it is not expected that such properties of TTPC would be realised in the flowback water. Nevertheless these COPCs were included in the quantitative evaluation of environmental risks (refer to Section 5.0). The risk assessment was conducted using a combination of theoretical calculations and the results of flowback water sampling. Based on the conceptual site model, the potentially complete exposure pathways identified and assessed in the risk assessment comprised the following:

• Incidental ingestion and dermal contact by trespassers at the flowback fluid holding tanks; and

• Potential releases of water to aquatic environments. The results of the risk assessment indicated the following • No unacceptable risks to trespassers were identified.

• Risks to the environment are considered to be negligible or

low. This is further supported by direct toxicity assessment results, which demonstrates that the flowback water is of similar toxicity to the background CSG water. The likelihood that any of these chemicals may be discharged to an environment where any level of exposure may occur is considered highly unlikely, due to the implementation of existing operational management measures. The identified level of risk is supported by review of historic and existing operations where no accidental releases of flowback water from the holding tanks have occurred.

Operational controls which can further minimise the potential for exposures include the installation of fencing and signage around the flowback storage tanks; routine operational and security patrols to prevent trespassing; Implementation of spill containment procedures; Routine gathering network inspections and evaluation of production rate data; Routine holding tank inspections to check for leakage of flow back fluid; freeboard buffer included above high fluid level automatic pump shut-off system, in the event of heavy rainfall.

These operational and management controls can be further supported by the following recommendations:

• Maintain compliance with Origin’s Stimulation Impact Monitoring Plan (Q-LNG01-15-MP-1124), which has been addressed to monitor the impact of hydraulic fracturing in the project area.

• Where possible, temporarily install pressure monitoring transducers in landholder bores installed with 1.5 km (1 order of magnitude greater than the estimated hydraulic fracturing radius of influence) of gas wells to be hydraulically fractured. These transducers could be used to monitor groundwater pressure the aquifers targeted by landholder bores throughout the hydraulic fracturing operation.

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Loss of containment of radioactive materials sometimes used during hydraulic fracturing operations

Radioactive substances are occasionally used in low concentrations as a tracer material for the assessment of the vertical extent hydraulic fracturing activities.

Exposure of workers, residents or the environment to potentially hazardous radioactive material, resulting from loss of containment occurring:

• Whilst in transit to site;

• During the mixing of hydraulic fracturing fluid onsite;

• (In diluted form) during the storage and transportof well flowback fluid; or

• During disposal from site..

When radioactive materials is used as part of the hydraulic fracturing operation, additional risk mitigation measures are implemented, these include:

• Implementation of safety proceduresspecific to the containment, use anddisposal of radioactive material.

• Preparation of a Radiation Safety andProtection Plan (RSPP), approved byQueensland Health.

Despite the control measures put in place to minimise the risk of radioactive material spills, the potential pathway for exposure persists, hence the risk is not eliminated. Further assessment is warranted regarding the risks of using radioactive material during hydraulic fracturing operations. This is addressed in Section 6.2 .

The quantitative risk assessment for the use of Protechnics ZeroWash bead tracers (containing the radionuclides Ir-192, Sb-124, and Sc-46) at the Origin Ramyard Pilot site demonstrated that there are no adverse human health impacts from the use of radiological tracers on-site and off-site (during transport). On this basis, the existing exposure controls implemented by Origin and Protechnics for hydraulic fracturing activities and management of flow back material, in accordance with the manufacturer specifications are considered sufficient for the management of low and acceptable human health impacts.

In addition, based on published half-life data of 83.8 days, the radioactive tracer will not persistent in the environment and will below analysis detection limit in a short time period.

Risk mitigation achieved via existing Origin protocols (e.g. Radiation Safety Protection Plan development, material handling procedures).

Harm to residents or fauna due to noise or vibrations from hydraulic fracturing operations

Significant noise and vibrations can be created during hydraulic fracturing operations by the pumps, blenders, generators used to conduct the operation.

This noise has the potential to harm residents or fauna in the short or long term.

During the hydraulic fracturing planning phase, Origin model the noise that will be produced during hydraulic fracturing operations. If residents’ houses/buildings are considered to be located in an area in which they may be disrupted by the noise of the hydraulic fracturing operation, Origin temporarily relocate residents for the course of the works on the well (typically several days).

The potential pathway for noise to harm residents is removed by the protocols Origin has in place (noise modelling and relocation).

Further assessment is warranted regarding the risk of noise or vibrations harming fauna. This is addressed in Section 6.1.

Noise assessment and modelling found that, depending on the location and nature of the activities, there is potential for hydraulic fracturing to have noise impacts on sensitive receptors within the APLNG operational area, albeit for short periods of time (see Section 6.1).

Origin have conducted detailed noise modelling pre stimulation to assess those receptors that may be subject noise emissions above the EA criteria. Where an exceedance occurs the mitigating measure is for Origin to obtain an alternative arrangement with the resident which essentially allows them to seek alternative accommodation for the duration of the activity (at Origin’s cost). Alternative arrangements for noise is a provision of the EA.

Occupational noise is addressed through Health and safety risk assessments. The Environmental Authority addresses environmental (ambient) noise only. Due to the short term nature of the activity, Origin consider the impact to fauna low (therefore accepting the risk with no mitigation).

Risk mitigation achieved via existing Origin protocols (e.g. resident relocation)

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Sub-

surf

ace

Envi

ronm

ent Contamination

of groundwater in the target coal seams, which is then accessed by landholder bores

Previous hydraulic fracturing pilot campaigns have demonstrated that not all hydraulic fracturing chemicals are recovered from the well (hence coal seam) during the flow-back period.

In locations where groundwater resources are limited, some landholders in the project area have installed water bores which source groundwater from the target coal seams (see Figure 24). Typically groundwater sourced from coal seams within the project area is suitable only for stock watering purposes, due to its high salinity (Section 2.2.5).

Based on the hydrogeological setting within the project area (Section 2.2.3), in order for the pathway to be valid in the context of exposure to hydraulic fracturing fluids, a groundwater supply bore would need to source groundwater from either:

thin the hydraulically fractured zone of the coal seam; or

2. Down hydraulic gradient of the hydraulicallyfractured zone, within the target coal seam.For example, if a landholder were in install anew bore, sufficiently close and down hydraulicgradient of a hydraulically fractured gas well andscreened in the target coal seam, then there is apotential exposure pathway for residualchemicals to flow in groundwater and over timereach the landholder bore and be brought tosurface.

The second scenario assumes that following the hydraulic fracturing procedure, the coal seam is not depressurised by the CSG well.

APLNG have protocols in place which preclude hydraulic fracturing operations impacting landholder bores.

Scenario 1

Prior to commencing a hydraulic fracturing campaign, Origin perform Baseline Assessments of all groundwater bores within 1km of horizontal separation from a target well. Part of this assessment is to understand the precise location of bores and their likely source aquifer. If a landholder bore is potentially screened within the radius of influence of a hydraulic fracturing operation (both horizontally and vertically), that gas well is not hydraulically fractured. Hence Scenario 1 becomes invalid.

Scenario 2

Typically Origin commence depressurising the coal seam within weeks of the conclusion of the hydraulic fracturing operation. On the basis that depressurisation commences, Scenario 2 becomes invalid as any hydraulic fracturing chemicals remnant within the coal seam will flow towards the CSG well.

Scenario 1 The protocols that Origin has in place to prevent hydraulic fracturing occurring near landholder bores screened in target coal seams, negate the requirement for further consideration of the risks of Scenario 1.

Scenario 2 Despite Origin typically commencing depressurisation of the coal seam within weeks of the hydraulic fracturing operation, the potential that this does not occur cannot be eliminated entirely. For example, Origin elect not to commence depressurisation of a pilot gas field following hydraulic fracturing, for operational reasons.

Hence an understanding of the potential for chemicals remaining in the coal seam to migrate in groundwater is achieved with a fate and transport assessment (see Section 3.5). The risk associated with leaving radiological tracers in hydraulically fractured zoned is performed in considered in Section 6.2 .

The understanding garnered from these assessments also informs whether the cumulative impact of residual chemicals sourced from multiple hydraulically fractured gas wells has the potential to increase the risk of Scenario 2.

Modelling of the fate and transport of COPCs residual in the coal seam after hydraulic fracturing (see Section 3.5) determined minimal potential for COPC migration beyond the leading edge of the hydraulically fractured zone. The most soluble of the COPCs was simulated to migrate 9 m beyond the hydraulically fractured zone over 1000 years.

Risk mitigation achieved via Origin’s existing Stimulation Impact Monitoring Plan (Q-LNG01-15-MP-1124),

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Appendix A Hydraulic Fracturing Fluid Mass Balance

APLNG Hydraulic Fracturing Risk AssessmentAppendix A ‐ Hydraulic Fluid Systems Mass Balance

Chemical Name CAS Number Density (kg/L) Volume of Chemical (L) Volume Fraction (%v/v) Chemical Mass in Fluid (kg) Mass Fraction (% w/w) Concentration in

Injected Fluid (mg/L)

Flowback Concentration Assuming 20% Mass Recovery

(mg/L)


(mg/L)Potassium chloride 7447‐40‐7 1.99Hydrochloric Acid 7647‐01‐0 1.152Guar gum 9000‐30‐0 0.7Monoethanolamine borate 26038‐87‐9 1.16Acetic acid (60%) 64‐19‐7 1.05 285 0.03% 299 0.02985% 312 62.3974378 187.1923134Lactose 63‐42‐3 1.525Citric Acid 77‐92‐9 1.542Shellac, ammonium salt 68308‐35‐8 1.28Tributyl tetradecyl phosphonium chloride 81741‐28‐8 1Coffee Extract 68916‐18‐7 1Sodium polyacrylate 9003‐04‐7 1.22Hemicellulase Enzyme 9012‐54‐8 0.88Sodium bisulfite 7631‐90‐5 1.48Talc, Magnesium Silicate 14807‐96‐6 2.75Sodium hydroxide (caustic soda) 1310‐73‐2 2.13 9 0.0009% 19 0.00191% 20 3.997189248 11.991567741‐Propanaminium, 3‐amino‐n‐(carboxy methyl)‐n,n‐dimethyl‐n‐coco alkyl 61789‐40‐0 0.98

Sodium chloride 7647‐14‐5 2.165Glycerine/Glycerol 56‐81‐5 1.261Sorbitan, monododecanoate, poly(oxy‐1,2‐diethanediyl) 9005‐64‐5 1.8Sulfuric Acid 7664‐93‐9 1.1Sodium Lauryl Sulfate 9004‐82‐4 1.1Sodium Carboxymethyl Cellulose 9004‐32‐4 1.6Maltodextrin 9050‐36‐6 1.6Aluminium Sulfate 10043‐01‐3 2.7Potassium borate 1332‐77‐0 1.9Diammonium peroxidisulphate 7727‐54‐0 2.0Potassium hydroxide 1310‐58‐3 2.1Glutataldehyde 111‐30‐8 1.1Gelatins 9000‐70‐8 0.7Non‐crystalline silica (impurity) 7631‐86‐9 2.0Diatomaceous earth, calcined 91053‐39‐3 0.5Magnesium nitrate 10377‐60‐3 2.345‐chloro‐2‐methyl‐2h‐isothiazol‐3‐one 26172‐55‐4 1.25Magnesium chloride 7786‐30‐3 2.322‐methyl‐2h‐isothiazol‐3‐onemethylisothiazolinone or MIT

2682‐20‐4 1.35

Cristobalite 14464‐46‐1 2.30Sodium Hypochloride 7681‐52‐9 1.11 141 0.01% 156.51 0.01561% 163 32.63432912 97.902987362,2`,2"‐nitrilotriethanol (triethanolamine) 102‐71‐6 1.12Ethylene glycol 107‐21‐1 1.11Fumaric acid 110‐17‐8 1.64Boronatrocalcite 1319‐33‐1 1.97Sodium tetraborate 1330‐43‐4 1.73Monosodium fumarate 7704‐73‐6 2.09Boric acid 10043‐35‐3 1.44Vinylidene chloride/methylacrylate copolymer 25038‐72‐6 1.78Diutan 595585‐15‐2 2.50

ProppantsSilicon Dioxide (quartz / sand) 100 Mesh 14808‐60‐7 2.65Silicon Dioxide (quartz / sand) 40/70 14808‐60‐8 2.65 1705 0.17% 4518.25 0.45064%Silicon Dioxide (quartz / sand) 20/40 14808‐60‐9 2.65 16490 1.69% 43698.50 4.35836%Carbolite 20/40Silicon Dioxide (quartz / sand) 16/30 2.65

WaterWater in additives 7732‐18‐5 0.995 511 0.05% 508 0.05071%Water 7732‐18‐5 0.995 958228 98.04% 953437 95.09293%

NitrogenNitrogen 7727‐37‐9 0.001251

Total Chemical Additivies 435 475 0.04737%Total Proppant 18195 48217 4.80899%Total Water (in additives) 511 508 0.05071%Total Make Up Water 958228 953437 95.09293%Total Nitrogen

% Chemical Additivies% Proppant% Water (in additives)% Make Up Water% Nitrogen

Page 1 of 8


Chemical Name CAS Number Density (kg/L) Volume of Chemical (L) Volume Fraction (%v/v) Chemical Mass in Fluid (kg) Mass Fraction (% w/w) Concentration in

Injected Fluid (mg/L)Flowback Concentration Assuming

20% Mass Recovery (mg/L)


(mg/L)Potassium chloride 7447‐40‐7 1.99Hydrochloric Acid 7647‐01‐0 1.152Guar gum 9000‐30‐0 0.7Monoethanolamine borate 26038‐87‐9 1.16Acetic acid (60%) 64‐19‐7 1.05 186 0.0273% 196 0.0280% 291.19 58 175Lactose 63‐42‐3 1.525Citric Acid 77‐92‐9 1.542Shellac, ammonium salt 68308‐35‐8 1.28Tributyl tetradecyl phosphonium chloride 81741‐28‐8 1Coffee Extract 68916‐18‐7 1Sodium polyacrylate 9003‐04‐7 1.22Hemicellulase Enzyme 9012‐54‐8 0.88Sodium bisulfite 7631‐90‐5 1.48Talc, Magnesium Silicate 14807‐96‐6 2.75Sodium hydroxide (caustic soda) 1310‐73‐2 2.131‐Propanaminium, 3‐amino‐n‐(carboxy methyl)‐n,n‐dimethyl‐n‐coco alkyl 61789‐40‐0 0.98

Sodium chloride 7647‐14‐5 2.165Glycerine/Glycerol 56‐81‐5 1.261Sorbitan, monododecanoate, poly(oxy‐1,2‐diethanediyl) 9005‐64‐5 1.8Sulfuric Acid 7664‐93‐9 1.1Sodium Lauryl Sulfate 9004‐82‐4 1.1Sodium Carboxymethyl Cellulose 9004‐32‐4 1.6Maltodextrin 9050‐36‐6 1.6Aluminium Sulfate 10043‐01‐3 2.7Potassium borate 1332‐77‐0 1.9Diammonium peroxidisulphate 7727‐54‐0 2.0Potassium hydroxide 1310‐58‐3 2.1Glutataldehyde 111‐30‐8 1.1Gelatins 9000‐70‐8 0.7Non‐crystalline silica (impurity) 7631‐86‐9 2.0Diatomaceous earth, calcined 91053‐39‐3 0.5 47.7 0.0070% 22.4 0.0032% 33.35 6.7 20.0Magnesium nitrate 10377‐60‐3 2.34 5.0 0.0007% 11.7 0.0017% 17.41 3.5 10.45‐chloro‐2‐methyl‐2h‐isothiazol‐3‐one 26172‐55‐4 1.25 1.9 0.0003% 2.4 0.0003% 3.53 0.7 2.1Magnesium chloride 7786‐30‐3 2.32 1.0 0.0001% 2.2 0.0003% 3.34 0.7 2.02‐methyl‐2h‐isothiazol‐3‐onemethylisothiazolinone or MIT

2682‐20‐4 1.35 0.6 0.0001% 0.8 0.0001% 1.12 0.2 0.7

Cristobalite 14464‐46‐1 2.30 0.2 0.0000% 0.4 0.0001% 0.55 0.1 0.3Sodium Hypochloride 7681‐52‐9 1.112,2`,2"‐nitrilotriethanol (triethanolamine) 102‐71‐6 1.12Ethylene glycol 107‐21‐1 1.11Fumaric acid 110‐17‐8 1.64Boronatrocalcite 1319‐33‐1 1.97Sodium tetraborate 1330‐43‐4 1.73Monosodium fumarate 7704‐73‐6 2.09Boric acid 10043‐35‐3 1.44Vinylidene chloride/methylacrylate copolymer 25038‐72‐6 1.78Diutan 595585‐15‐2 2.50

ProppantsSilicon Dioxide (quartz / sand) 100 Mesh 14808‐60‐7 2.65Silicon Dioxide (quartz / sand) 40/70 14808‐60‐8 2.65 1134 0.17% 3006 0.43%Silicon Dioxide (quartz / sand) 20/40 14808‐60‐9 2.65 9912 1.45% 26267 3.76%Carbolite 20/40Silicon Dioxide (quartz / sand) 16/30 2.65

WaterWater in additives 7732‐18‐5 0.995Water 7732‐18‐5 0.995 671899 98.35% 668540 96%

0NitrogenNitrogen 7727‐37‐9 0.001251

Total Chemical Additivies 243 236Total Proppant 11046 29273Total Water (in additives)Total Make Up Water 671899 668540Total Nitrogen

% Chemical Additivies 0.03% 0.03%% Proppant 1.37% 3.64%% Water (in additives) 0.00% 0.00%% Make Up Water 83.44% 83.02%% Nitrogen

Page 2 of 8


Chemical Name CAS Number Density (kg/L) Volume of Chemical Constituent (L)Volume Fraction of

Chemicalin Total Fluid (%v/v)

Chemical Mass in Fluid (kg)Mass Fraction of

Chemical in Total Fluid (%w/w)

Concentration in Injected Fluid (mg/L)


(mg/L)


(mg/L)Potassium chloride 7447‐40‐7 1.99 6718 0.83428% 13,369 1.29656% 19934 3987 11960Hydrochloric Acid 7647‐01‐0 1.152 4559 0.56617% 5,252 0.50935% 7831 1566 4699Guar gum 9000‐30‐0 0.7 1160 0.14406% 812 0.07875% 1211 242 726Monoethanolamine borate 26038‐87‐9 1.16 354 0.04396% 411 0.03983% 612 122 367Acetic acid (60%) 64‐19‐7 1.05 331 0.04111% 348 0.03371% 518 104 311Lactose 63‐42‐3 1.525 212 0.02633% 323 0.03135% 482 96 289Citric Acid 77‐92‐9 1.542 150 0.01863% 231 0.02243% 345 69 207Shellac, ammonium salt 68308‐35‐8 1.28 53 0.00658% 68 0.00658% 101 20 61Tributyl tetradecyl phosphonium chloride 81741‐28‐8 1 44 0.00546% 44 0.00427% 66 13 39Coffee Extract 68916‐18‐7 1 31 0.00385% 31 0.00301% 46 9 28Sodium polyacrylate 9003‐04‐7 1.22 26 0.00323% 32 0.00308% 47 9 28Hemicellulase Enzyme 9012‐54‐8 0.88 17.1 0.00212% 15 0.00146% 22 4 13Sodium bisulfite 7631‐90‐5 1.48 5.2 0.00065% 8 0.00075% 11 2 7Talc, Magnesium Silicate 14807‐96‐6 2.75 0.87 0.00011% 2 0.00023% 4 0.7 2Sodium hydroxide (caustic soda) 1310‐73‐2 2.13 0.76 0.00009% 2 0.00016% 2 0.5 11‐Propanaminium, 3‐amino‐n‐(carboxy methyl)‐n,n‐dimethyl‐n‐coco alkyl 61789‐40‐0 0.98

Sodium chloride 7647‐14‐5 2.165Glycerine/Glycerol 56‐81‐5 1.261Sorbitan, monododecanoate, poly(oxy‐1,2‐diethanediyl) 9005‐64‐5 1.8Sulfuric Acid 7664‐93‐9 1.1Sodium Lauryl Sulfate 9004‐82‐4 1.1Sodium Carboxymethyl Cellulose 9004‐32‐4 1.6Maltodextrin 9050‐36‐6 1.6Aluminium Sulfate 10043‐01‐3 2.7Potassium borate 1332‐77‐0 1.9Diammonium peroxidisulphate 7727‐54‐0 2.0Potassium hydroxide 1310‐58‐3 2.1Glutataldehyde 111‐30‐8 1.1Gelatins 9000‐70‐8 0.7Non‐crystalline silica (impurity) 7631‐86‐9 2.0Diatomaceous earth, calcined 91053‐39‐3 0.5Magnesium nitrate 10377‐60‐3 2.345‐chloro‐2‐methyl‐2h‐isothiazol‐3‐one 26172‐55‐4 1.25Magnesium chloride 7786‐30‐3 2.322‐methyl‐2h‐isothiazol‐3‐onemethylisothiazolinone or MIT

2682‐20‐4 1.35

Cristobalite 14464‐46‐1 2.30Sodium Hypochloride 7681‐52‐9 1.112,2`,2"‐nitrilotriethanol (triethanolamine) 102‐71‐6 1.12Ethylene glycol 107‐21‐1 1.11Fumaric acid 110‐17‐8 1.64Boronatrocalcite 1319‐33‐1 1.97Sodium tetraborate 1330‐43‐4 1.73Monosodium fumarate 7704‐73‐6 2.09Boric acid 10043‐35‐3 1.44Vinylidene chloride/methylacrylate copolymer 25038‐72‐6 1.78Diutan 595585‐15‐2 2.50

ProppantsSilicon Dioxide (quartz / sand) 100 Mesh 14808‐60‐7 2.65 4316 0.53599% 11431 1.10862%Silicon Dioxide (quartz / sand) 40/70 14808‐60‐8 2.65 1133 0.14070% 3000 0.29095%Silicon Dioxide (quartz / sand) 20/40 14808‐60‐9 2.65 129129 16.03605% 342007 33.16908%Carbolite 20/40Silicon Dioxide (quartz / sand) 16/30 2.65

WaterWater in additives 7732‐18‐5 0.995 13552 1.68297% 13484 1.30775%Water 7732‐18‐5 0.995 643450 79.90766% 640233 62.09209%


Total Chemical Additivies 13662 20,947Total Proppant 134578 356438Total Water (in additives) 13552 13484Total Make Up Water 643450 640233Total Nitrogen

% Chemical Additivies 1.70% 2.60%% Proppant 16.71% 44.26%% Water (in additives) 1.68% 1.67%% Make Up Water 79.91% 79.51%% Nitrogen

Page 3 of 8


Chemical Name CAS Number Density (kg/L)Volume of Chemical Constituent (L) for

773080L FRACVolume Fraction (%v/v) Chemical Mass in Fluid (kg) Mass Fraction (% w/w)



(mg/L)


(mg/L)Potassium chloride 7447‐40‐7 1.99 7883 0.69372% 15,687 1.39826% 19856 3971 11914Hydrochloric Acid 7647‐01‐0 1.152 4559 0.40120% 9,072 0.80866% 11484 2297 6890Guar gum 9000‐30‐0 0.7 1348 0.11863% 2,683 0.23910% 3395 679 2037Monoethanolamine borate 26038‐87‐9 1.16 417 0.03670% 830 0.07397% 1050 210 630Acetic acid (60%) 64‐19‐7 1.05 331 0.02913% 659 0.05871% 834 167 500Lactose 63‐42‐3 1.525 239 0.02103% 476 0.04239% 602 120 361Citric Acid 77‐92‐9 1.542 150 0.01320% 299 0.02661% 378 76 227Shellac, ammonium salt 68308‐35‐8 1.28 63 0.00554% 125 0.01117% 159 32 95Tributyl tetradecyl phosphonium chloride 81741‐28‐8 1 48 0.00422% 96 0.00851% 121 24 73Coffee Extract 68916‐18‐7 1 31 0.00273% 62 0.00550% 78 16 47Sodium polyacrylate 9003‐04‐7 1.22 26 0.00229% 52 0.00461% 65 13 39Hemicellulase Enzyme 9012‐54‐8 0.88 18.2 0.00160% 36 0.00323% 46 9 28Sodium bisulfite 7631‐90‐5 1.48 5.2 0.00046% 10 0.00092% 13 3 8Talc, Magnesium Silicate 14807‐96‐6 2.75 1.0 0.00009% 2 0.00018% 3 1 2Sodium hydroxide (caustic soda) 1310‐73‐2 2.13 0.76 0.00007% 2 0.00013% 2 0 11‐Propanaminium, 3‐amino‐n‐(carboxy methyl)‐n,n‐dimethyl‐n‐coco alkyl 61789‐40‐0 0.98 1132 0.09962% 2,253 0.20079% 2851 570 1711Sodium chloride 7647‐14‐5 2.165 546 0.04805% 1,087 0.09685% 1375 275 825Glycerine/Glycerol 56‐81‐5 1.261 156 0.01373% 310 0.02767% 393 79 236Sorbitan, monododecanoate, poly(oxy‐1,2‐diethanediyl) 9005‐64‐5 1.8Sulfuric Acid 7664‐93‐9 1.1Sodium Lauryl Sulfate 9004‐82‐4 1.1Sodium Carboxymethyl Cellulose 9004‐32‐4 1.6Maltodextrin 9050‐36‐6 1.6Aluminium Sulfate 10043‐01‐3 2.7Potassium borate 1332‐77‐0 1.9Diammonium peroxidisulphate 7727‐54‐0 2.0Potassium hydroxide 1310‐58‐3 2.1Glutataldehyde 111‐30‐8 1.1Gelatins 9000‐70‐8 0.7Non‐crystalline silica (impurity) 7631‐86‐9 2.0Diatomaceous earth, calcined 91053‐39‐3 0.5Magnesium nitrate 10377‐60‐3 2.345‐chloro‐2‐methyl‐2h‐isothiazol‐3‐one 26172‐55‐4 1.25Magnesium chloride 7786‐30‐3 2.322‐methyl‐2h‐isothiazol‐3‐onemethylisothiazolinone or MIT

2682‐20‐4 1.35


ProppantsSilicon Dioxide (quartz / sand) 100 Mesh 14808‐60‐7 2.65 4281 0.37673% 11340 1.01078%Silicon Dioxide (quartz / sand) 40/70 14808‐60‐8 2.65 1133 0.09971% 3000 0.26740%Silicon Dioxide (quartz / sand) 20/40 14808‐60‐9 2.65Carbolite 20/40 113442 9.98306% 300460 26.78127%Silicon Dioxide (quartz / sand) 16/30 2.65

WaterWater in additives 7732‐18‐5 0.995 16080 1.41506% 16080 1.43328% NAWater 7732‐18‐5 0.995 757000 66.61708% 757000 67.47462% NA

NitrogenNitrogen 7727‐37‐9 0.001251 227455 20.01637% 285 0.02536% 360 72 216

Total Chemical Additivies 16954 33,739Total Proppant 118856 314800Total Water (in additives) 16080 16080Total Make Up Water 757000 757000Total Nitrogen 227455 285

% Chemical Additivies 1.49% 3.01%% Proppant 10.46% 28.06%% Water (in additives) 1.42% 1.43%% Make Up Water 66.62% 67.47%% Nitrogen 20.02% 0.03%

Page 4 of 8


Chemical Name CAS Number Density (kg/L)Equivalent Volume of

Mass Fraction (per kg of mixture)

Volume Fraction (%v/v)

Chemical Mass in Fluid (kg)

Mass Fraction (% w/w)



(mg/L)


(mg/L)Potassium chloride 7447‐40‐7 1.99Hydrochloric Acid 7647‐01‐0 1.152Guar gum 9000‐30‐0 0.7Monoethanolamine borate 26038‐87‐9 1.16Acetic acid (60%) 64‐19‐7 1.05Lactose 63‐42‐3 1.525Citric Acid 77‐92‐9 1.542Shellac, ammonium salt 68308‐35‐8 1.28Tributyl tetradecyl phosphonium chloride 81741‐28‐8 1Coffee Extract 68916‐18‐7 1Sodium polyacrylate 9003‐04‐7 1.22Hemicellulase Enzyme 9012‐54‐8 0.88 1.13636E‐06 0.0001% 0.0001% 1.0 0.2 0.6Sodium bisulfite 7631‐90‐5 1.48Talc, Magnesium Silicate 14807‐96‐6 2.75Sodium hydroxide (caustic soda) 1310‐73‐2 2.131‐Propanaminium, 3‐amino‐n‐(carboxy methyl)‐n,n‐dimethyl‐n‐coco alkyl 61789‐40‐0 0.98

Sodium chloride 7647‐14‐5 2.165Glycerine/Glycerol 56‐81‐5 1.261Sorbitan, monododecanoate, poly(oxy‐1,2‐diethanediyl) 9005‐64‐5 1.8 0.000102717 0.0103% 0.0189% 188.8 37.8 113.3Sulfuric Acid 7664‐93‐9 1.1 0.000149321 0.0149% 0.0165% 164.8 33.0 98.9Sodium Lauryl Sulfate 9004‐82‐4 1.1 9.90476E‐05 0.0099% 0.0104% 103.9 20.8 62.3Sodium Carboxymethyl Cellulose 9004‐32‐4 1.6 0.003131875 0.3128% 0.5011% 5005.5 1001.1 3003.3Maltodextrin 9050‐36‐6 1.6 7.8481E‐05 0.0078% 0.0124% 123.9 24.8 74.3Aluminium Sulfate 10043‐01‐3 2.7 0.000247566 0.0247% 0.0661% 660.3 132.1 396.2Potassium borate 1332‐77‐0 1.9Diammonium peroxidisulphate 7727‐54‐0 2.0Potassium hydroxide 1310‐58‐3 2.1Glutataldehyde 111‐30‐8 1.1Gelatins 9000‐70‐8 0.7Non‐crystalline silica (impurity) 7631‐86‐9 2.0Diatomaceous earth, calcined 91053‐39‐3 0.5Magnesium nitrate 10377‐60‐3 2.345‐chloro‐2‐methyl‐2h‐isothiazol‐3‐one 26172‐55‐4 1.25Magnesium chloride 7786‐30‐3 2.322‐methyl‐2h‐isothiazol‐3‐onemethylisothiazolinone or MIT

2682‐20‐4 1.35


ProppantsSilicon Dioxide (quartz / sand) 100 Mesh 14808‐60‐7 2.65Silicon Dioxide (quartz / sand) 40/70 14808‐60‐8 2.65Silicon Dioxide (quartz / sand) 20/40 14808‐60‐9 2.65Carbolite 20/40Silicon Dioxide (quartz / sand) 16/30 2.65

WaterWater in additives 7732‐18‐5 0.995 0.008375879 0.8367% 0.8334% NAWater 7732‐18‐5 0.995 0.988915578 98.7827% 98.3971% NA


Total Chemical AdditiviesTotal ProppantTotal Water (in additives)Total Make Up WaterTotal Nitrogen

% Chemical Additivies 0.003810144 0.3805% 0.6254%% Proppant% Water (in additives) 0.008375879 0.8367% 0.8334%% Make Up Water 0.988915578 98.7827% 98.3971%% Nitrogen

Page 5 of 8


Chemical Name CAS Number Density (kg/L)Volume of Chemical Constituent (L) FOR

800,000L FRACVolume Fraction

(%v/v)Equivalent Volume of Mass Fraction (% v/w)

Chemical Mass in Fluid (kg)Mass Fraction

(% w/w) Concentration in

Injected Fluid (mg/L)


(mg/L)


(mg/L)Potassium chloride 7447‐40‐7 1.99Hydrochloric Acid 7647‐01‐0 1.152 4648 0.58104% 0.4804% 5355 0.5534% 7688 1538 4613Guar gum 9000‐30‐0 0.7 2356 0.29446% 0.2435% 1649 0.1704% 2367 473 1420Monoethanolamine borate 26038‐87‐9 1.16Acetic acid (60%) 64‐19‐7 1.05Lactose 63‐42‐3 1.525Citric Acid 77‐92‐9 1.542Shellac, ammonium salt 68308‐35‐8 1.28Tributyl tetradecyl phosphonium chloride 81741‐28‐8 1Coffee Extract 68916‐18‐7 1Sodium polyacrylate 9003‐04‐7 1.22Hemicellulase Enzyme 9012‐54‐8 0.88 94 0.01172% 0.0097% 83 0.0085% 118 24 71Sodium bisulfite 7631‐90‐5 1.48Talc, Magnesium Silicate 14807‐96‐6 2.75Sodium hydroxide (caustic soda) 1310‐73‐2 2.131‐Propanaminium, 3‐amino‐n‐(carboxy methyl)‐n,n‐dimethyl‐n‐coco alkyl 61789‐40‐0 0.98

Sodium chloride 7647‐14‐5 2.165Glycerine/Glycerol 56‐81‐5 1.261 164 0.02046% 0.0169% 206 0.0213% 296 59 178Sorbitan, monododecanoate, poly(oxy‐1,2‐diethanediyl) 9005‐64‐5 1.8Sulfuric Acid 7664‐93‐9 1.1Sodium Lauryl Sulfate 9004‐82‐4 1.1Sodium Carboxymethyl Cellulose 9004‐32‐4 1.6Maltodextrin 9050‐36‐6 1.6Aluminium Sulfate 10043‐01‐3 2.7Potassium borate 1332‐77‐0 1.9 325 0.04058% 0.0335% 633 0.0654% 909 182 545Diammonium peroxidisulphate 7727‐54‐0 2.0 124 0.01549% 0.0128% 248 0.0256% 356 71 214Potassium hydroxide 1310‐58‐3 2.1 111 0.01393% 0.0115% 234 0.0242% 336 67 202Glutataldehyde 111‐30‐8 1.1 103 0.01285% 0.0106% 109 0.0113% 156 31 94Gelatins 9000‐70‐8 0.7 84 0.01047% 0.0087% 59 0.0061% 84 17 51Non‐crystalline silica (impurity) 7631‐86‐9 2.0 2 0.00026% 0.0002% 4 0.0004% 6 1 4Diatomaceous earth, calcined 91053‐39‐3 0.5Magnesium nitrate 10377‐60‐3 2.345‐chloro‐2‐methyl‐2h‐isothiazol‐3‐one 26172‐55‐4 1.25Magnesium chloride 7786‐30‐3 2.322‐methyl‐2h‐isothiazol‐3‐onemethylisothiazolinone or MIT

2682‐20‐4 1.35


ProppantsSilicon Dioxide (quartz / sand) 100 Mesh 14808‐60‐7 2.65 103480 12.93494% 10.6945% 274221 28.3405%Silicon Dioxide (quartz / sand) 40/70 14808‐60‐8 2.65Silicon Dioxide (quartz / sand) 20/40 14808‐60‐9 2.65Carbolite 20/40Silicon Dioxide (quartz / sand) 16/30 2.65

WaterWater in additives 7732‐18‐5 0.995Water 7732‐18‐5 0.995 688510 86.06380% 71.1570% 685068 70.8013% NA


Total Chemical Additivies 8010 0 8579Total Proppant 103480 0 274221Total Water (in additives)Total Make Up Water 688510 1 685068Total Nitrogen

% Chemical Additivies 1.0013% 0.0000% 0.8864%% Proppant 12.9349% 0.0000% 28.3325%% Water (in additives)% Make Up Water 86.0638% 0.0001% 70.7811%% Nitrogen

Page 6 of 8


Chemical Name CAS Number Density (kg/L) Volume of Chemical (L) Volume Fraction (%v/v) Chemical Mass in Fluid (kg) Mass Fraction (% w/w) Concentration in Injected Fluid

(mg/L)


(mg/L)


(mg/L)Potassium chloride 7447‐40‐7 1.99 1167 0.852% 2322 1.39% 19438 3888 11663Hydrochloric Acid 7647‐01‐0 1.152 301 0.220% 347 0.2085% 2906 581 1744Guar gum 9000‐30‐0 0.7 511 0.373% 358 0.2149% 2995 599 1797Monoethanolamine borate 26038‐87‐9 1.16Acetic acid (60%) 64‐19‐7 1.05Lactose 63‐42‐3 1.525Citric Acid 77‐92‐9 1.542Shellac, ammonium salt 68308‐35‐8 1.28Tributyl tetradecyl phosphonium chloride 81741‐28‐8 1Coffee Extract 68916‐18‐7 1Sodium polyacrylate 9003‐04‐7 1.22Hemicellulase Enzyme 9012‐54‐8 0.88Sodium bisulfite 7631‐90‐5 1.48Talc, Magnesium Silicate 14807‐96‐6 2.75 0.02 0.000% 0.06 0.0000% 0.5 0.09 0.28Sodium hydroxide (caustic soda) 1310‐73‐2 2.13 15.26 0.011% 32.50 0.0195% 272 54 1631‐Propanaminium, 3‐amino‐n‐(carboxy methyl)‐n,n‐dimethyl‐n‐coco alkyl 61789‐40‐0 0.98

Sodium chloride 7647‐14‐5 2.165 33.01 0.024% 71.47 0.0429% 598 120 359Glycerine/Glycerol 56‐81‐5 1.261 38.56 0.028% 48.62 0.0292% 407 81 244Sorbitan, monododecanoate, poly(oxy‐1,2‐diethanediyl) 9005‐64‐5 1.8Sulfuric Acid 7664‐93‐9 1.1Sodium Lauryl Sulfate 9004‐82‐4 1.1Sodium Carboxymethyl Cellulose 9004‐32‐4 1.6Maltodextrin 9050‐36‐6 1.6Aluminium Sulfate 10043‐01‐3 2.7Potassium borate 1332‐77‐0 1.9Diammonium peroxidisulphate 7727‐54‐0 2.0 34.99 0.026% 69.98 0.0420% 586 117 351Potassium hydroxide 1310‐58‐3 2.1Glutataldehyde 111‐30‐8 1.1Gelatins 9000‐70‐8 0.7Non‐crystalline silica (impurity) 7631‐86‐9 2.0 0.3 0.000% 0.60 0.0004% 5 1 3Diatomaceous earth, calcined 91053‐39‐3 0.5 9.12 0.007% 4.29 0.0026% 36 7 22Magnesium nitrate 10377‐60‐3 2.34 0.97 0.001% 2.27 0.0014% 19 4 115‐chloro‐2‐methyl‐2h‐isothiazol‐3‐one 26172‐55‐4 1.25 0.37 0.000% 0.46 0.0003% 4 1 2Magnesium chloride 7786‐30‐3 2.32 0.19 0.000% 0.44 0.0003% 4 1 22‐methyl‐2h‐isothiazol‐3‐onemethylisothiazolinone or MIT

2682‐20‐4 1.35 0.11 0.000% 0.15 0.0001% 1 0 1

Cristobalite 14464‐46‐1 2.30 0.03 0.000% 0.07 0.0000% 1 0.12 0.35Sodium Hypochloride 7681‐52‐9 1.112,2`,2"‐nitrilotriethanol (triethanolamine) 102‐71‐6 1.12 50.08 0.037% 56.09 0.0337% 469 94 282Ethylene glycol 107‐21‐1 1.11 77.77 0.057% 86.32 0.0518% 723 145 434Fumaric acid 110‐17‐8 1.64 1.92 0.001% 3.14 0.0019% 26 5 16Boronatrocalcite 1319‐33‐1 1.97 56.07 0.041% 110.46 0.0663% 924 185 555Sodium tetraborate 1330‐43‐4 1.73 4.25 0.003% 7.35 0.0044% 62 12 37Monosodium fumarate 7704‐73‐6 2.09 1.5 0.001% 3.14 0.0019% 26 5 16Boric acid 10043‐35‐3 1.44 2.2 0.002% 3.17 0.0019% 27 5 16Vinylidene chloride/methylacrylate copolymer 25038‐72‐6 1.78 1.12 0.001% 1.99 0.00120% 17 3 10Diutan 595585‐15‐2 2.50 0.06 0.000% 0.15 0.00009% 1 0 1

ProppantsSilicon Dioxide (quartz / sand) 100 Mesh 14808‐60‐7 2.65 17515 12.78% 46414 27.87%Silicon Dioxide (quartz / sand) 40/70 14808‐60‐8 2.65Silicon Dioxide (quartz / sand) 20/40 14808‐60‐9 2.65Carbolite 20/40Silicon Dioxide (quartz / sand) 16/30 2.65

WaterWater in additives 7732‐18‐5 0.995Water 7732‐18‐5 0.995 117172 85.53% 116587 70.01%


Total Chemical Additivies 2308 3,530 0.35209%Total Proppant 17515 46414 4.62920%Total Water (in additives)Total Make Up Water 117172 116587 11.62799%Total Nitrogen


Page 7 of 8


Chemical Name CAS Number Density (kg/L) Volume of Chemical (L) Volume Fraction (%v/v) Chemical Mass in Fluid (kg) Mass Fraction (% w/w) Concentration in Injected Fluid

(mg/L)


(mg/L)


(mg/L)Potassium chloride 7447‐40‐7 1.99 1167 0.852% 2322 1.39% 19457 3891 11674Hydrochloric Acid 7647‐01‐0 1.152 301 0.220% 599 0.3600% 5024 1005 3015Guar gum 9000‐30‐0 0.7 406 0.297% 809 0.4856% 6778 1356 4067Monoethanolamine borate 26038‐87‐9 1.16Acetic acid (60%) 64‐19‐7 1.05Lactose 63‐42‐3 1.525Citric Acid 77‐92‐9 1.542Shellac, ammonium salt 68308‐35‐8 1.28Tributyl tetradecyl phosphonium chloride 81741‐28‐8 1Coffee Extract 68916‐18‐7 1Sodium polyacrylate 9003‐04‐7 1.22Hemicellulase Enzyme 9012‐54‐8 0.88Sodium bisulfite 7631‐90‐5 1.48Talc, Magnesium Silicate 14807‐96‐6 2.75 0.02 0.000% 0 0.0000% 0 0.07 0.20Sodium hydroxide (caustic soda) 1310‐73‐2 2.131‐Propanaminium, 3‐amino‐n‐(carboxy methyl)‐n,n‐dimethyl‐n‐coco alkyl 61789‐40‐0 0.98

Sodium chloride 7647‐14‐5 2.165 33 0.024% 66 0.0394% 550 110 330Glycerine/Glycerol 56‐81‐5 1.261 38.56 0.028% 77 0.0461% 643 129 386Sorbitan, monododecanoate, poly(oxy‐1,2‐diethanediyl) 9005‐64‐5 1.8Sulfuric Acid 7664‐93‐9 1.1Sodium Lauryl Sulfate 9004‐82‐4 1.1Sodium Carboxymethyl Cellulose 9004‐32‐4 1.6Maltodextrin 9050‐36‐6 1.6Aluminium Sulfate 10043‐01‐3 2.7Potassium borate 1332‐77‐0 1.9 75.79 0.055% 151 0.0906% 1264 253 758Diammonium peroxidisulphate 7727‐54‐0 2.0 34.97 0.026% 70 0.0418% 583 117 350Potassium hydroxide 1310‐58‐3 2.1 26.73 0.020% 53 0.0319% 446 89 267Glutataldehyde 111‐30‐8 1.1Gelatins 9000‐70‐8 0.7Non‐crystalline silica (impurity) 7631‐86‐9 2.0 0.3 0.000% 1 0.0004% 5 1 3Diatomaceous earth, calcined 91053‐39‐3 0.5 9.11 0.007% 18 0.0109% 152 30 91Magnesium nitrate 10377‐60‐3 2.34 0.97 0.001% 2 0.0012% 16 3 105‐chloro‐2‐methyl‐2h‐isothiazol‐3‐one 26172‐55‐4 1.25 0.37 0.000% 1 0.0004% 6 1 4Magnesium chloride 7786‐30‐3 2.32 0.19 0.000% 0 0.0002% 3 1 22‐methyl‐2h‐isothiazol‐3‐onemethylisothiazolinone or MIT

2682‐20‐4 1.35 0.11 0.000% 0 0.0001% 2 0 1

Cristobalite 14464‐46‐1 2.30 0.03 0.000% 0 0.0000% 1 0.10 0.30Sodium Hypochloride 7681‐52‐9 1.112,2`,2"‐nitrilotriethanol (triethanolamine) 102‐71‐6 1.12 50.06 0.037% 100 0.0598% 835 167 501Ethylene glycol 107‐21‐1 1.11Fumaric acid 110‐17‐8 1.64Boronatrocalcite 1319‐33‐1 1.97Sodium tetraborate 1330‐43‐4 1.73Monosodium fumarate 7704‐73‐6 2.09Boric acid 10043‐35‐3 1.44Vinylidene chloride/methylacrylate copolymer 25038‐72‐6 1.78 1.12 0.001% 2 0.00134% 19 4 11Diutan 595585‐15‐2 2.50

ProppantsSilicon Dioxide (quartz / sand) 100 Mesh 14808‐60‐7 2.65 17508 12.78% 34841 20.92%Silicon Dioxide (quartz / sand) 40/70 14808‐60‐8 2.65Silicon Dioxide (quartz / sand) 20/40 14808‐60‐9 2.65Carbolite 20/40Silicon Dioxide (quartz / sand) 16/30 2.65

WaterWater in additives 7732‐18‐5 0.995Water 7732‐18‐5 0.995 117172 85.53% 233173


Total Chemical Additivies 2146 4,270 0.43%Total Proppant 17508 34841 3.47%Total Water (in additives)Total Make Up Water 117172.4 233173 23.26%Total Nitrogen


Page 8 of 8

AECOM



Appendix B Hydraulic Fracturing

Fluid Eco Toxicological Data

Hydrobiology

Freshwater Ecotoxicity of Coal Seam Gas Hydraulic Stimulation Fluids

Report for Origin June 2016

Freshwater Ecotoxicity of Coal Seam Gas Hydraulic Stimulation Fluids June 2016 ii

Hydrobiology

Title page photographs

from:

ABN

Cooper Creek, South West Qld. Hydrobiology

Duckweed from http://biorefinerycentre.ifr.ac.uk/duckweed-and-biofuel-production/ [Accessed 16/05/2016]

Rainbowfish from http://rainbowfish.angfaqld.org.au/splendida.htm [Accessed 16/05/2016] photo© Gunther

Schmida

26 096 574 659

GST The company is registered for GST

Head Office 27 / 43 Lang Parade

Auchenflower QLD 4066

Registered Office c/- de Blonk Smith and Young Accountants

GPO 119

Brisbane, QLD 4001

Postal Address PO Box 2151

Toowong QLD 4066

Phone 61 (07) 3721 0100

Fax 61 (07) 3721 0151

Email Contact [email protected]

Website http://www.hydrobiology.biz

© Hydrobiology Pty Ltd 2016

Disclaimer: This document contains confidential information that is intended only for the use by Hydrobiology’s Client. It is

not for public circulation or publication or to be used by any third party without the express permission of either the Client or

Hydrobiology Pty. Ltd. The concepts and information contained in this document are the property of Hydrobiology Pty Ltd.

Use or copying of this document in whole or in part without the written permission of Hydrobiology Pty Ltd constitutes an

infringement of copyright.

While the findings presented in this report are based on information that Hydrobiology considers reliable unless stated

otherwise, the accuracy and completeness of source information cannot be guaranteed. Furthermore, the information compiled

in this report addresses the specific needs of the client, so may not address the needs of third parties using this report for their

own purposes. Thus, Hydrobiology and its employees accept no liability for any losses or damage for any action taken or not

taken on the basis of any part of the contents of this report. Those acting on information provided in this report do so entirely at

their own risk.

http://biorefinerycentre.ifr.ac.uk/duckweed-and-biofuel-production/

http://rainbowfish.angfaqld.org.au/splendida.htm

mailto:[email protected]

http://www.hydrobiology.biz/

Freshwater Ecotoxicity of Coal Seam Gas Hydraulic Stimulation Fluids June 2016 iii

Hydrobiology



Document Control Information

Date Printed 17/06/2016

Project Title Origin Stimulation Fluid Ecotox Program

Project Manager Janina Beyer-Robson

Job Number ORI1501 Report Number 1

Document Title Freshwater Ecotoxicity of Coal Seam Gas Hydraulic Stimulation Fluids

Document File Name Document Status Originator(s) Reviewed

By Authorised

By Date

Origin_Ecotox_Draft_Report_RV0-1_JBR

Draft JBR 27/05/2016


Draft JBR DH JBR / DH 07/06/2016


Draft with comments from CG and JC

JBR DH JBR 17/06/2016

Distribution

Document File Name Description Issued To Issued By Issue Date Origin_Ecotox_Draft_Methods_&_Ecotox_Result_Tables

Draft Methods and Result tables with

attached ecotox lab appendices

Chathu Gamage

Janina Beyer-Robson

27/05/2016

Origin_Ecotox_Draft_Report_RV1-0

Draft Report Chathu Gamage

Janina Beyer-Robson

07/06/2016

Origin_Ecotox_Draft_Report_RV2-0

Final Report Mack Dreyer Janina Beyer-Robson

17/06/2016

Freshwater Ecotoxicity of Coal Seam Gas Hydraulic Stimulation Fluids June 2016 iv

Hydrobiology

GLOSSARY OF TERMS AND ACRONYMS

Acute toxicity – Rapid adverse effect caused by a substance in a living organism. The term

can be used to define either the exposure or the response to an exposure (effect). The

Australian and New Zealand water quality guidelines (ANZECC/ARMCANZ 2000) define

acute exposure as being between 24 and 96 hours duration for multi-celled organisms and

being between 24 and 72 hours duration for single-celled organisms.

Acute to chronic ratio (ACR) – The ratio of the acute toxicity to the chronic toxicity of a

species to a toxicant (Warne 2001).

Chronic toxicity – A biological response to exposure to a toxicant that takes a prolonged

period to appear and persists for a prolonged period. The term can be used to define either

the exposure of an aquatic species or its response to an exposure (effect). The Australian and

New Zealand water quality guidelines (ANZECC/ARMCANZ 2000) define chronic exposure

as being greater than 96 hours duration for multi-celled organisms and being equal to or

greater than 72 hours duration for single-celled organisms.

Coal Seam Gas (CSG) Water – groundwater/seam water brought to the surface of the earth,

or moved underground in connection with exploring for, or producing coal seam gas.

Control (control treatment) – In ecotoxicity tests the control is that treatment in which the

test organisms are not subjected to the test substance. The control is used as a standard

comparison, to check that the outcome of the experiment is a reflection of the tested

substance concentrations and not some unknown factor.

Cross-Linked fluid or gel - in this report cross-linked fluid or gel refers to the stimulation

fluid named ‘cross-linked’ by the service providers. Cross-linked gels are generally used to

increase the viscosity of the stimulation fluid where it is necessary to transport the proppant

to the stimulation zone to keep fractures open. This is one out of several types of fluid

systems used for stimulating wells. Please see definition of hydraulic stimulation fluid.

Direct toxicity assessment (DTA) – The use of toxicity tests to determine the acute and/or

chronic toxicity of effluents and other mixtures of potential toxicants.

EC – Electrical Conductivity, which is a measure of the ability of a fluid to transport an

electrical current, usually via dissolved ions and so is related to the amount of total dissolved

salts (TDS).

Ecotoxicity – The inherent potential or capacity of a chemical/mixture/substance to cause

adverse effects in a living organism.

Ecotoxicity test – A test that exposes living organisms to a range of concentrations of a

substance and/or mixture that is under investigation, and evaluates the organism’s

responses.

Freshwater Ecotoxicity of Coal Seam Gas Hydraulic Stimulation Fluids June 2016 v

Hydrobiology

Endpoint – The biological response of test organisms in toxicity tests that is measured (e.g.

lethality, immobilisation).

Hydraulic stimulation - a technique used to increase the permeability of a natural

underground reservoir that is undertaken above the formation pressure and involves the

addition of chemicals. It includes hydraulic stimulation / hydrofraccing, fracture acidizing

and the use of proppant treatments.

Hydraulic stimulation fluid - the fluid injected underground to increase permeability. For

clarity, the term stimulation fluid only applies to fluid injected down well post-perforation.

The two types of fluids discussed in this report include ‘treated water fluid’ and ‘ cross-

linked fluid.’ The two fluid systems described are selected representative fluids as there are

several types of fluid systems used for stimulating wells.

IC10 or ICp – The concentration that inhibits an endpoint by ’p’ percent (e.g. the IC10 (reprod) is

the concentration that inhibits reproduction by 10%). It represents a point estimate of a

concentration of test material that causes a designated percent inhibition (p) compared with

the control. The ICp is usually expressed as a time-dependent value, e.g. 24-hour IC10 is the

concentration estimated to cause an effect on 10% of the test organisms after 24 hours of

exposure.

NATA – National Association of Testing Authorities. NATA is the authority that provides

independent assurance of technical competence through a proven network of best practice

industry experts for customers who require confidence in the delivery of their products and

services. NATA provides assessment, accreditation and training services to laboratories and

technical facilities throughout Australia and internationally

Protective concentration (PC) – The concentration predicted by species sensitivity

distribution methods that will potentially protect a chosen percentage of species from

experiencing toxic effects. For example, the PC99 should protect 99% of species in the

ecosystem being considered if the tested species adequately reflect the sensitivities of all

ecosystem constituents. The toxic effects that are being prevented will depend on the type of

toxicity data used to derive the PC values. Thus, if sub-lethal IC10 data are used to generate

a PC95 – it will protect 95% of species from experiencing long term chronic and sub-lethal

effects.

Proppant – Hydraulic stimulation is a process using high pressure pumps to inject water,

stimulation chemicals and sand into wells to open and connect cracks present in the coal

seam gas (CSG) reservoirs. Sand or similar particulates are used in order to keep the

fractures open. The mix of particulates used is referred to as the ‘proppant’.

Species Sensitivity Distribution (SSD) - An assessment approach in which the endpoints

for several species are statistically combined to illustrate the spread of sensitivities and to

potentially estimate the likelihood of a certain proportion of species (e.g. 95%) is affected at a

certain exposure level.

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Sub-lethal – A biological response that is less severe than death. Examples of sub-lethal

effects include inhibition of reproduction, reduction in growth, reduction in population

growth, inhibition of fertilisation and inhibition of development.

Toxicity – The inherent potential or capacity of a chemical/mixture/substance to cause

adverse effects in a living organism.

Treated water fluid – in this report ‘treated water’ fluid refers to the hydraulic stimulation

fluid named ‘treated water’ by the service providers. This does not refer to treatment of a

water source by a treatment plant. Treated water fluid is generally applied where less

viscous fluids are required for stimulation. This is one out of several types of fluid systems

used for stimulating wells. Please see definition of hydraulic stimulation fluid.

Trigger value (TV)– The concentration (or load) of the key performance indicators measured

for the ecosystem, below which there exists a low (defined) risk that adverse biological

(ecological) effects will occur. It indicates a threshold which, if exceeded should ‘trigger’

some action, either further ecosystem-specific investigations or implementation of

management/remedial actions.

Freshwater Ecotoxicity of Coal Seam Gas Hydraulic Stimulation Fluids June 2016 vii

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TABLE OF CONTENTS

Glossary of Terms and Acronyms ..................................................................................................... iv

1 Introduction .................................................................................................................................. 1

1.1 Aim and objectives ............................................................................................................... 1

Phase 1: Background ecotoxicity of CSG water ....................................................................... 2

Phase 2: Ecotoxicity of representative hydraulic stimulation fluids .................................... 2

Phase 3: Ecotoxicity of flowback waters ................................................................................... 2

1.2 Report structure .................................................................................................................... 3

2 Background ................................................................................................................................... 4

2.1 CSG water and salinity ........................................................................................................ 4

2.2 Hydraulic stimulation fluids .............................................................................................. 5

2.3 Flowback waters ................................................................................................................... 6

3 Ecotoxicology methods ............................................................................................................... 7

3.1 Ecotoxicity testing for each species .................................................................................... 8

3.1.1 Algal growth test: Raphidocelis subcapitata (Green alga) .......................................... 8

3.1.2 Plant growth test: Landoltia punctata (Duckweed) ................................................... 8

3.1.3 Juvenile survival test: Caridina nilotica (Freshwater shrimp) ................................. 9

3.1.4 Survival test: Ceriodaphnia cf. dubia (Daphnia) ......................................................... 9

3.1.5 Reproductive impairment test (3-brood): Ceriodaphnia cf dubia (Daphnia) ........ 10

3.1.6 Survival test: Chironomus tepperi (Midge) ................................................................ 10

3.1.7 Larval imbalance test: Melanotaenia splendida (Rainbowfish) ............................... 10

3.1.8 Population growth: Hydra viridissima (Green hydra) ............................................ 11

3.2 Data analysis ....................................................................................................................... 11

3.2.1 Calculating the IC10 ................................................................................................... 11

3.2.2 Converting acute data to chronic equivalent .......................................................... 12

3.2.3 Derivation of trigger values ...................................................................................... 12

4 Phase 1: CSG water .................................................................................................................... 13

4.1 Objectives ............................................................................................................................. 13

4.2 CSG water quality characteristics .................................................................................... 13

4.3 Sampling and methods ...................................................................................................... 14

4.3.1 Sampling ...................................................................................................................... 14

4.3.2 Chemical testing ......................................................................................................... 15

4.4 Results .................................................................................................................................. 15

4.5 Conclusions ......................................................................................................................... 16

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5 Phase 2: Hydraulic stimulation fluids .................................................................................... 17

5.1 Objectives ............................................................................................................................. 17

5.2 Composition of the hydraulic stimulation fluids ........................................................... 17

5.3 Methods ............................................................................................................................... 18

5.4 Results .................................................................................................................................. 21

5.4.1 Stimulation fluid toxicity ........................................................................................... 21

5.4.2 Difference between stimulation fluids from RAM24 and RAM23 ...................... 22

5.5 Conclusions ......................................................................................................................... 22

6 Phase 3: Flowback waters ......................................................................................................... 24

6.1 Objectives ............................................................................................................................. 24

6.2 Selection of flowback waters ............................................................................................. 24

6.3 Sampling and Methods ...................................................................................................... 24

6.4 Results .................................................................................................................................. 25

6.4.1 Ecotoxicity ................................................................................................................... 25

6.4.2 Hydrochemistry .......................................................................................................... 26

6.5 Conclusions ......................................................................................................................... 30

7 Overall Discussion ..................................................................................................................... 31

8 References ................................................................................................................................... 34

Appendix 1 Ecotox Sample Summary

Appendix 2 Ecotox laboratory Report from ESA

Appendix 3 Ecotox laboratory Report from CQU

Appendix 4 IC10 Calculation

Appendix 5 Notice of Completion of hydrauliic fracturing activities

Appendix 6 Hydraulic Stimulation fluid mixing procedure

Appendix 7 SSD plots

Appendix 8 Ecotox IC 10 and ACR data summary

Appendix 9 Water Quality Data

Appendix 10 Independent Peer review and response

TABLES

Table 2-1: Additives commonly used in the cross-linked hydraulic stimulation fluids in the

Surat Basin ............................................................................................................................................. 6

Table 3-1: Test organisms used for direct toxicity assessment ....................................................... 7

Table 4-1: IC10 (expressed in %) for each species and Trigger Value (TV in % solution) for the

CSG water ............................................................................................................................................ 15

Table 5-1: Additives in the two cross-linked hydraulic stimulation fluids tested .................... 18

Table 5-2: Chemical additives used for mixing the hydraulic stimulation fluids with source

water ..................................................................................................................................................... 20

Table 5-3: IC10 (expressed in %) for each species and Trigger Value (TV in % solution) for

the hydraulic stimulation fluids ....................................................................................................... 21

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Table 5-4: Water quality for the source water and hydraulic stimulation fluid RAM24 and

RAM23 ................................................................................................................................................. 23

Table 6-1: IC10 (expressed in %) for each species and Trigger Value (TV in % solution) for

the flowback waters ........................................................................................................................... 25

Table 6-2: Water Quality parameters from the tested CSG water (Phase 1) and flowback

waters (Phase 3) .................................................................................................................................. 29

Table 7-1: Summary of all ecotoxicity results including IC10 (expressed in %) for each

species and trigger value for 95% species protection. ................................................................... 33

FIGURES

Figure 1-1: Outline of ecotoxicity program ....................................................................................... 3

Figure 4-1: PCA of CSG groundwater by well names (light blue symbols) and the tested CSG

water from Reedy Creek (dark blue symbol) ................................................................................. 14

Figure 6-1: PCA of CSG groundwater (light blue symbols), flowback waters the tested CSG

water RC-PW006 (dark blue symbol). ............................................................................................. 27

PLATES

Plate 5-1: Photographs of cross-linked hydraulic stimulation fluid A) Unbroken cross-linked

gel; and B) Broken cross-linked fluid .............................................................................................. 19

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1 INTRODUCTION This project is being undertaken to satisfy Condition 50f from the EPBC approval for the

Australian Government. The Condition states that Origin must include as part of their

Coal Seam Gas Water Monitoring and Management Plan (WMMP):

“Details of constituent components of any hydraulic fracturing agents and any other reinjected fluids and

their toxicity as total effluent toxicity and ecotoxicity, based on methods outlined in the National Water

Quality Management Strategy”

Origin contracted Hydrobiology to develop and undertake an ecotoxicity testing program

to assess the incremental ecotoxicity of representative hydraulic stimulation fluids. This

was placed in the context of the natural ecotoxicity of Coal Seam Gas (CSG) groundwater

to surface freshwater organisms. In line with the Condition, the ecotoxicity testing of

representative hydraulic stimulation fluids as whole mixtures was undertaken. Origin has

undertaken a desktop based assessment on individual chemical components and provides

the identity of these components on its website1.

This general scope of the ecotoxicity testing program was developed based on discussions

with the regulator through their scientific advisors ERISS (Environmental Research

Institute of the Supervising Scientist) and Queensland Gas Company (QGC) in 2013. The

Origin CSG ecotoxicity testing framework and components are consistent with the work

plan which was developed from these discussions (see CSG Fraccing Fluid Toxicology Work

Plan2 (Hydrobiology, 2013)).

1.1 Aim and objectives

The aim of this program was to understand the potential hazard of hydraulic stimulation

fluids associated with CSG waters on surface freshwater organisms. The project has three

main phases as outlined in Figure 1-1. The objectives within each of the three phases are

further described below.

1 http://www.aplng.com.au/newsroom/fraccing-fact-sheets [Accessed 12/05/2015]

2http://www.qgc.com.au/ebooks/qgc_Stage_3_WMMP_Dec_13_Appendices/Appendix_M1_CSG_Fraccing_Flui

d_Ecotoxicology/index.html#/1/ [Accessed 10/12/2015]

http://www.aplng.com.au/newsroom/fraccing-fact-sheets

http://www.qgc.com.au/ebooks/qgc_Stage_3_WMMP_Dec_13_Appendices/Appendix_M1_CSG_Fraccing_Fluid_Ecotoxicology/index.html#/1/

http://www.qgc.com.au/ebooks/qgc_Stage_3_WMMP_Dec_13_Appendices/Appendix_M1_CSG_Fraccing_Fluid_Ecotoxicology/index.html#/1/


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Phase 1: Background ecotoxicity of CSG water

As CSG water has higher salinity than regional surface water, it was expected that there

would be some adverse response from the freshwater organisms to CSG water. Therefore,

the objective within this phase was:

1. To determine the background ecotoxicity of a representative CSG water.

Phase 2: Ecotoxicity of representative hydraulic stimulation fluids

To assess the ecotoxicity of hydraulic stimulation fluids, two representative fluids were

selected based on typical chemical additive mixtures used by Origin for stimulating wells

during 2015. The objective within this phase was:

1. To determine the combined ecotoxicity of representative hydraulic stimulation

fluids constituted in source water used to stimulate the wells.

This assessed the response of freshwater species to hydraulic stimulation fluids

representative of how the fluids were constituted in the field. The source water used for

the Origin wells was treated water from the Talinga water treatment facility.

Phase 3: Ecotoxicity of flowback waters

In Phase 3 the hazard potential of flowback waters in comparison with pre-stimulated CSG

waters (Phase 1) and a representative hydraulic stimulation fluid (Phase 2) were examined.

The objectives within this phase were:

1. To determine the sensitivity of freshwater species to flowback waters in comparison

with pre-stimulation CSG waters and the hydraulic stimulation fluids; and

2. To assess the ecotoxicity of flowback water at two stages – early stage flowback and

a second flowback at a later stage (when water quality conditions were expected to

have returned to near background conditions).

The physico-chemical and chemical properties of the flowback waters were representative

of the hydraulic stimulation fluid tested in Phase 2 and representative of the types of well

stimulation in the Surat Basin in 2015.


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Figure 1-1: Outline of ecotoxicity program

By assessing the ecotoxicity of the described components in the section above, the results

were used to identify the relative background ecotoxicity of CSG water compared with the

ecotoxicity of hydraulic stimulation fluids and flowback waters on surface freshwater

organisms.

1.2 Report structure The report follows the general structure of the three phases as indicated in Figure 1-1:

Section 2 provides background information and rationale for the project;

Section 3 describes the ecotoxicology methods and test species used in the program;

Section 4 to 6 follow the format of the three phases, where background data, the

selection of representative test solutions, specific methods used and results for each

phase are discussed separately; and

Section 7 brings all the results together and discusses the implications of the

findings.

Species protective concentrations Relative toxicity of stimulation fluid to CSG

water and flowback waters

Algae Duckweed Daphnia Shrimp Midge Rainbowfish

Ecotoxicity TestsTest Species

CSG Water

CSG WaterReedy Creek

Phase 1

Stimulation Fluid & Source Water

Stimulation Fluid

RAM 24

Stimulation Fluid

RAM 23

Phase 2

CSG Flowback Waters

Early stage Flowback RAM 24

Late stageFlowback

HCK16

Phase 3

Early stageFlowback RAM 23


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2 BACKGROUND The following sections provide further background data on each of the phases:

Phase 1: CSG waters;

Phase 2: Representative hydraulic stimulation fluids; and

Phase 3: Flowback waters.

2.1 CSG water and salinity

Salinity is a measure of the total concentration of ions in the water. Electrical conductivity

(EC) is a measure of the ability of the water to transmit an electrical current, which is

proportional to the concentrations of electrically charged ions in solution. In groundwater,

EC and ion composition vary in response to catchment characteristics such as geology and

associated water/rock interactions. The mean EC measured in the current Origin Surat

Basin well water data set is approximately 9,044 µS/cm, with a range of 3,700 –

16,000 µS/cm (based on Origin data provided from well water monitoring between 2006

and 2013). In comparison, fresh waters are generally considered to have an EC of

< 1000 µS/cm (ANZECC/ARMCANZ 2000). Therefore, it was foreseeable that the

freshwater test organisms would likely be sensitive when exposed to CSG water compared

with the surface fresh waters of the region.

Sensitivity of freshwater organisms to changes in EC is dependent on a variety of factors

including previous exposure to higher EC environments, duration of the exposure,

adaptation of the organisms and variation in internal osmoregulatory mechanisms. Thus,

EC sensitivity can vary widely between different taxa as well as within taxa from different

regions (Kefford et al 2003; Dunlop et al 2008). The ecotoxicity of saline solutions to

freshwater organisms has also been shown to be dependent on the ion composition of

waters (Mount et al 1997; Soucek and Kennedy, 2011). Mount et al (1997) tested

combinations of salts of major ions (e.g. NaCl/NaSO4) and defined a relationship between

the concentration of individual ions and ecotoxicity. This work showed that relative ion

toxicity was K+ > HCO3- ≈ Mg2+ > Cl- > SO42-. Dunlop et al (2008) reported sensitivity values

for marine salts on macroinvertebrates and in a further study Dunlop et al (2011) used

laboratory prepared solutions with ionic compositions similar to stream waters in the

Fitzroy Catchment, to test the ecotoxicity of sulfate. This allowed salinity tolerance to be

directly tested for combinations of ions. Dunlop et al (2008, 2011) showed that on the basis

of EC, the stream water solutions with high salinity were more toxic than marine salts for

the majority of the organisms. Further, Prasad et al (2012) assessed the ecotoxicity of saline

mine waters on macroinvertebrates in the Bowen Basin. Prasad et al (2012) estimated the

protective concentration (PC) for 95% of species derived from a species sensitivity

distribution (SSD) to be 2000 µS/cm, though differences in ecotoxicity were observed

between different mine waters.


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Based on the results from Dunlop et al (2008, 2011) and Prasad et al (2012), the higher

salinities in the CSG water were expected to result in salinity sensitivity from freshwater

organisms in the region. Response to higher salinities in CSG waters has also been

confirmed by Takahashi et al (2012) in a study carried out as part of the Healthy

Headwaters Program by the former Department of Environment and Resource

Management (currently Department of Environment and Heritage Protection). Takahashi

et al (2012) undertook a direct toxicity assessment (DTA) of CSG-related waters in relation

to Reverse Osmosis (RO) permeate waters, and reported that overall CSG water had higher

toxicity than RO permeate. Further, it was reported that the ecotoxicity levels of the CSG

water was site specific, suggesting a response by freshwater organisms as a result of

salinity and differences in the chemical composition of the CSG waters. Therefore,

differences in species sensitivity may occur not only from the increased salinity of CSG

water compared with the surface waters, but also may depend on the ionic composition of

the representative CSG test waters.

2.2 Hydraulic stimulation fluids

Origin employs fracture stimulation on wells where gas is tightly held in low permeable

reservoirs, to enhance the permeability of the formation and hydrocarbon flow. Origin

engages service providers to carry out the stimulation activity, for their expertise in

the chemical blends and stimulation process. There are multiple additives which can be

used in hydraulic stimulation fluids, based on the geology and proppant transport

mechanisms required for stimulating a well. A list of all chemical constituents

individually assessed and approved for use by Origin is provided on the Origin website3.

Both treated waters and cross-linked fluids were used for well stimulation in the region;

cross-linked fluids were selected for testing as this would capture the worst-case-scenario

as it includes the stimulation fluid with the largest number of chemical additives used.

Cross-linked fluid is used to increase the viscosity of the hydraulic stimulation fluid where

this is necessary to transport the proppant to the stimulation zone to keep fractures open.

Cross-linked fluids were commonly used in the Ramyard tenements in 2015 and thus two

fluid systems were selected to be tested in this program (a cross-linked and a nitrogen

foam cross-linked stimulation fluid). Table 5-1 summarises the chemical additives used in

the cross-linked stimulation fluids along with a brief summary of the purpose of each

chemical additive (for further details on the stimulation fluids see Section 5).

3 http://www.aplng.com.au/newsroom/fraccing-fact-sheets [Accessed 12/05/2015]

http://www.aplng.com.au/newsroom/fraccing-fact-sheets


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Table 2-1: Additives commonly used in the cross-linked hydraulic stimulation fluids in the Surat Basin

Chemical Component

Purpose of the Additive

Biocide** To reduce gel degradation and sulfate reducing bacteria to prevent generation of H2S.

Guar** Used to thicken the fluid and provide viscosity.

pH Adjuster** Used to buffer the water to a target pH range of 6 - 8. This is generally used when the pH of the water is high due to bicarbonates.

Clay Stabilizer** Used to stabilise mobile clays in the sub-surface that may block the flow of water and hydrocarbons.

Cross-linker** Used when higher viscosities are required for stimulation. The cross-linker causes the polymer chains to bind together creating a high viscosity fluid/gel (Unbroken gel viscosity 400 – 1000 cP)

Breaker** Used to break the viscosity of the fluid back to the consistency of water.

Surfactant* Promotes adequate foam viscosity for gas-liquid dispersion.

Nitrogen gas* Delivery mechanism during stimulation. ** Chemicals used in both cross linked and the nitrogen cross-linked fluid system

* Chemicals only used in the nitrogen foam cross-linked fluid system

2.3 Flowback waters

For the purpose of this report, the definition of flowback water is water that flows from a

well following well stimulation. The flowback stage is the measured percentage of the

total volume of flowback in relation to the total injected hydraulic stimulation fluid volume

(not including proppant).

As mentioned above, stimulation methods and the hydraulic stimulation fluid used are

dependent on local geology and well characteristics. The resulting flowback waters are

variable as a result of the regional hydrogeological characteristics of CSG waters, different

hydraulic stimulation fluids, well completions and workover processes, and the source

waters used to mix the hydraulic stimulation fluids prior to well stimulation. Further,

water quality may change with increasing volumes of flowback. With an initial increase in

water rate (as the well is brought online), the majority of the stimulation fluids will

flowback in the early stages of a well production.

To understand the hazards associated with hydraulic stimulation fluids, assessing the

response of freshwater organisms to flowback waters at various stages of flowback

provides an important basis for comparisons between background conditions of CSG water

and the hydraulic stimulation fluid.


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3 ECOTOXICOLOGY METHODS An independent review of this report was undertaken by Dr John C. Chapman, who has

over 29 years of experience in ecotoxicology and is a founding member of the Society for

Environmental Toxicology and Chemistry (the review response details are provided in

Appendix 0).

Given the need to screen a large number of test solutions with a number of species, the

ecotoxicity testing was carried out by two testing facilities: Ecotox Services Australasia

(ESA) and Central Queensland University (CQU). Seven species across multiple trophic

levels were selected based on available commercial tests and their relevance in the region.

The direct toxicity assessments (DTA) are described in Section 3.1, with a summary of the

test species and tests used provided in Table 3-1.

Table 3-1: Test organisms used for direct toxicity assessment

Test Organism Test Duration Test Type Testing Facility

Raphidocelis subcapitata (Freshwater alga)

72-hr (chronic) Algal growth inhibition/ Cell division test

ESA

Landoltia punctata (Duckweed) 96-hr (acute) Plant growth Inhibition CQU

Caridina nilotica (Freshwater shrimp) 96-hr (acute) Juvenile Survival CQU




168-hr (chronic) Reproductive impairment (3-brood)

ESA

Hydra viridissima (Freshwater hydra) 96-hr (acute) Population growth test ESA

Chironomus tepperi (Freshwater midge) 48-hr (acute) Survival ESA

Melanotaenia splendida (Rainbowfish) 96-hr (acute) Imbalance ESA

The test facilities for each test species are indicated; ESA – Ecotox Services Australia and CQU – Central Queensland

University.

ESA is a NATA-accredited laboratory and conducts ecotoxicity tests according to standard

methods based on the Organisation for Economic Co-operation and Development (OECD)

or United States Environmental Protection Agency (US EPA) protocols and consistent with

the ANZECC/ARMCANZ (2000) guidelines for direct toxicity assessment (DTA). For

ecotoxicity testing, standard synthetic water and/or a pure natural water source were used

as the test diluents as recommended by US EPA (2000) and described in the ESA test

reports and/or test facts sheets4. Methodologies and data for each test from ESA have been

provided in Appendix 2.

CQU is not NATA accredited, but CQU ran standard QA/QC protocols that were

consistent with standard ecotoxicology protocols including the ANZECC/ARMCANZ

4 http://www.ecotox.com.au/Test-Fact-Sheets [Accessed 23/10/2015]

http://www.ecotox.com.au/Test-Fact-Sheets


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(2000) guidelines. This included the requirements to meet criteria such as control

growth/survival and consistency in water quality parameters (pH, conductivity, dissolved

oxygen and temperature). For ecotoxicity testing, standard synthetic water and/or a pure

natural water source were used as the test diluents as recommended by US EPA (2000).

Methodologies and data for each test from CQU have been provided in Appendix 3.

3.1 Ecotoxicity testing for each species

3.1.1 Algal growth test: Raphidocelis subcapitata (Green alga)

Raphidocelis subcapitata (formerly known as Selenastrum capricornutum) is a ubiquitous green

algae commonly found in freshwaters. This unicellular microalga is commonly used as a

bioindicator due to its sensitivity to the presence of a wide range of toxicants in water.

Microalgae are important primary producers in aquatic ecosystems, are direct food sources

for zooplankton and fish larvae and are indirect food sources for higher trophic level

organisms.

The growth inhibition test is based on a US EPA protocol (2002). The algal growth test

involves exposing a fixed density of algae to the test material for a 72 h period, after which

the growth rate (cell division rate) or final cell biomass (in this case measured using the

light absorbance method rather than cell counts) is determined. The growth of the algae

exposed to the test substance is compared with the growth of algae in an appropriate

control to derive point estimates (in this case IC10) of ecotoxicity. A significant decrease

(statistical difference P ≤ 0.05) in growth rate or cell biomass relative to the controls is an

indication of ecotoxicity.

Test type: Chronic

Test end-point: Cell yield

Test duration: 72 hours

Testing facility: Ecotox Services Australia

3.1.2 Plant growth test: Landoltia punctata (Duckweed)

Landoltia punctata is a small aquatic, flowering macrophyte commonly known as

duckweed. L. punctata occurs in fresh waters in both tropical and temperate regions. The

duckweeds are ecologically relevant test organisms in that they are primary producers and

a source of food for waterfowl, fish and small invertebrates. By floating in mats on the

surface of still waters they also provide habitats for many small organisms. Unlike other

aquatic flowering plants, their small size and fast growth rates make them ideal for testing

in the laboratory.

This test is based on the OECD (2006) and US EPA (2002) protocols. A standard number of

vegetatively reproducing plants are exposed to a dilution series of the test substance for 4

days under controlled conditions. Frond numbers are counted at the end of the test. From

this the increase in frond numbers is calculated and compared with that of an appropriate


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control to determine the percentage inhibition of growth for each treatment. The data are

used to derive point estimates (in this case IC10) of ecotoxicity.

Test type: Acute

Test end-point: Specific growth rate and dry weight

Test duration: 96 hours (4 days)

Testing facility: CQ University

3.1.3 Juvenile survival test: Caridina nilotica (Freshwater shrimp)

Caridina nilotica is a widespread common Australian species of freshwater prawn native to

north-eastern Australia (and the Indo-east African region). The juvenile survival test is

based on the US EPA (2002) mysid shrimp. Juvenile shrimp are exposed to a range of

concentrations of the test solutions for 96 h. The test containers are checked every 24 h for

shrimp mortality and the results are statistically compared with the controls to determine

significant differences. The data are used to derive point estimates (in this case IC10) of

ecotoxicity.

Test type: Acute

Test end-point: Mortality


Testing facility: CQ University

3.1.4 Survival test: Ceriodaphnia cf. dubia (Daphnia)

Ceriodaphnia cf. dubia is a freshwater cladoceran and a widely used species for ecotoxicity

assessment programs in Australia and widely distributed in Australian inland waters. The

acute toxicity test is one of the most commonly used tests to assess the potential harm a

toxicant poses to freshwater aquatic ecosystems. The test is based on, and modified from

the US EPA protocol (2002). This test involves exposing laboratory reared Ceriodaphnia to

the test material for 48 h. The test is undertaken on a range of test material concentrations

and at the end of the exposure the number of surviving Ceriodaphnia in each concentration

is counted. Statistical analyses are then applied to determine the concentration that caused

a percentage of mortality to the test population (in this case IC10).

Test type: Acute





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3.1.5 Reproductive impairment test (3-brood): Ceriodaphnia cf dubia (Daphnia)

This test, also known as the 7-day partial life cycle test, is one of the most commonly used

chronic tests and is commonly performed alongside the 48 h acute testing of the same

species in order to obtain an acute-to-chronic ratio from the two tests.

The test begins with asexually reproducing female Ceriodaphnia that are less than six hours

old (i.e. neonates). These neonate females are exposed to a dilution series of the test

substance and transferred daily to fresh solutions of the same concentration. Each day,

observations are made on the survival of each female, the number of neonates produced

and neonate survival. Each female must be accounted for as alive, dead or missing, rather

than assuming missing animals are dead. The test is terminated when three broods have

been produced by each surviving control female (normally over a 5 - 6 day period). The

method is based on the Ceriodaphnia Survival and Reproduction Test developed by the US

EPA (2002). The data are used to derive a chronic point estimates (in this case IC10) of

ecotoxicity. A further difference in tests procedures between the reproductive impairment

and the acute test is the required feeding of the cladocerans during the longer chronic

exposures.

Test type: Chronic

Test end-point: Mortality and number of young produced

Test duration: 7 – 8 days


3.1.6 Survival test: Chironomus tepperi (Midge)

Chironomus tepperi is widely distributed throughout Australia and can rapidly colonise

freshly flooded environments (Stevens, 1994). In the test, ten larvae at the second-instar

stage are exposed to a dilution series of the test substance for 48 h. Observations of any

mortalities to the midge population are recorded at 24 h intervals. The method is based on

OECD Test method 219: Sediment-Water Chironomid Toxicity Testing (2004). The data are

used to derive point estimates (in this case IC10) of ecotoxicity.

Test type: Acute




3.1.7 Larval imbalance test: Melanotaenia splendida (Rainbowfish)

This freshwater fish has a widespread distribution in North-Eastern Australia extending

down to the Fitzroy River catchment (Allen et al 2003). M. splendida was used as a

representative rainbowfish for ecotoxicity testing, although it is not native to the

Condamine-Balonne catchment.


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This test involves exposing fish larvae to the test material for 96 h. A larval fish is recorded

as affected when imbalance is displayed. Imbalance refers to the loss of swimming ability

of the fish such that the fish can no longer remain upright. When a fish is observed to be

imbalanced, it is immediately removed from the test vessels and euthanized with an

anaesthetic. The data are used to derive point estimates (in this case IC10) of ecotoxicity.

Test type: Acute

Test end-point: Imbalance



3.1.8 Population growth: Hydra viridissima (Green hydra)

Hydra viridissima is referred to as ‘green’ hydra because of its green colouration resulting

from the presence of a symbiotic green alga in the gastrodermal cells of the hydra.

Asexually reproducing (budding) hydra are exposed to a dilution series of the test toxicant

for 96 hours. Observations of any changes to the hydra population (i.e. changes in the

number of intact hydroids, where one hydroid equals one animal plus any attached buds)

are recorded at 24 h intervals. The method is based on the hydra population growth test

described by Hyne et al (1996) and Riethmuller et al (2003). The data are used to derive

chronic point estimates (in this case IC10) of ecotoxicity.

Test type: Acute

Test end-point: population growth (number of hydra)



3.2 Data analysis

3.2.1 Calculating the IC10

ESA analysed the raw data using ToxCalc™ (V 5.0.23) and CQU analysed the raw data

using CETIS. Several toxicity statistics were generated using these packages including the

LOEC, NOEC, IC50 and IC10 (see glossary). In this report, the IC10 values were used for

all analysis (Inhibition Concentration (IC))5. The IC10 is the dilution of the test solution (in

% test solution) that is estimated to cause a response in 10% of species. The IC10 was

calculated using Trimmed Spearman-Karber analysis (Hamilton et al 1977, 1978),

Maximum Likelihood Probit analysis (Finney 1971) or Log-Logit Interpolations (US EPA

2002), depending on the test type and statistically appropriate method.

5 For tests where IC10 were not available these were calculated by Hydrobiology using R and

outputs provided in Appendix 4.


Hydrobiology

3.2.2 Converting acute data to chronic equivalent

As per ANZECC/ARMCANZ (2000) guidelines, to calculate the species sensitivity

distribution (SSD), acute data need to be converted to a chronic equivalent. To do this, an

acute to chronic ratio (ACR) is required. For the current testing program, a Ceriodaphnia

acute and chronic test was conducted for each test solution to derive an ACR. This ACR

specific to each test solution was then applied to each acute test (list of acute/chronic tests

provided in Table 3-1 and the ACR applied are listed in Appendix 8). As per

ANZECC/ARMCANZ (2000) guidelines the ACR can be applied to 50% effect data. In this

report the ACR was calculated and applied to the IC10 data which provide an additional

level of protection when deriving SSDs. Further, if the calculated chronic toxicity was

higher than the acute toxicity, an ACR of 1 was applied to ensure a more conservative

approach was used.

3.2.3 Derivation of trigger values

ANZECC/ARMCANZ (2000) provides a regime for allocating trigger values (TVs) for

contaminants. TVs were derived using the SSD method on IC10 data using the BurrliOZ

software package (Campbell et al 2000), provided as part of ANZECC/ARMCANZ (2000)

and subsequently updated by CSIRO6. SSDs are models of the variation in sensitivity of

species to a particular solution. SSD fitting by the software package BurrliOZ, uses a

flexible group of distributions (Burr Type III ) to estimate the proportion of species affected

as a function of stressor concentration or dose (Campbell et al 2000). From this a TV is

calculated; below which there exists a low likelihood that adverse biological (ecological)

effects will occur. For this project the calculated TV is the percent of the test solution that

will protect an inferred 95% of the species in the ecosystem. Since the IC10 data were used

to derive the TV, this means that the TV is inferred to protect 95% of species from

experiencing long-term chronic and sub-lethal effects. Hence, the lower the TV value, the

more toxic the solution.

6 https://research.csiro.au/software/burrlioz/ [Accessed 29/04/2016]

https://research.csiro.au/software/burrlioz/


Hydrobiology

4 PHASE 1: CSG WATER

4.1 Objectives

The objective of Phase 1 was to determine the ecotoxicity of a representative CSG water.

The rationale behind establishing baseline ecotoxicity was that the CSG water was

expected to have some level of ecotoxicity to surface-dwelling freshwater organisms as a

result of higher salinities in CSG waters compared with most surface waters in the region

(see background information in Section 2.1).

4.2 CSG water quality characteristics

The representative CSG water was collected from a non-stimulated well (RC-PW06J)

within the Reedy Creek tenement. This provides background / baseline conditions from

CSG waters (formation water pre-stimulation) from a similar location to that of the

flowback water

CSG waters were characterised based on ionic water quality data of other Origin CSG wells

in the Surat Basin. For this, routine CSG well monitoring data (from 2006 and 2013) from

eight Origin wells were analysed. Water quality parameters used in the analyses were pH,

electrical conductivity (EC as µS/cm), dissolved and suspended solids and concentrations

of major cations (K+, Na+, Ca2+, Mg2+) and anions (Cl-, SO42-, HCO3-, F-). Variables such as

trace metals were not included in the analysis as concentrations were generally low and

not consistently available across all samples.

Multivariate analysis using principal component analysis (PCA) was undertaken for which

two main CSG water types were identified based on the chemical properties of waters:

including bicarbonate dominated CSG water type and a chloride dominated CSG water

type. The analysis indicates that the CSG water collected from Reedy Creek for ecotoxicity

testing was representative of the bicarbonate CSG water type (see Figure 4-1). This

suggests the sample collected is towards a worst case scenario, given the higher toxicity of

bicarbonate noted in Section 2.1.


Hydrobiology

Figure 4-1: PCA of CSG groundwater by well names (light blue symbols) and the tested CSG water from Reedy Creek (dark blue symbol)

4.3 Sampling and methods

4.3.1 Sampling

To assess the background toxicity a CSG well from the Reedy Creek tenement was

sampled.

Water samples were collected by Bureau Veratis Minerals staff in 5 litre plastic

containers, provided by ESA via Hydrobiology. These containers are commonly

used for standard collection of test waters by ESA;

Standard procedure for sampling waters was to triple rinse each bottle with the

sample liquid prior to filling each bottle; and


Hydrobiology

All samples were shipped on ice overnight and stored at 4°C until ecotoxicity

testing was undertaken. Chain of custody forms were supplied with all shipments

and are attached in the ecotoxicology reports for each laboratory in Appendix 2 and

Appendix 3.

4.3.2 Chemical testing

Chemical analyses of water samples were undertaken at Origin’s contracted analysis

laboratory for the stimulation program, Symbio Alliance.

4.4 Results

The trigger values (TVs) for the CSG water was calculated using the species sensitivity

distribution method (SSD) (see Appendix 7). The TV for CSG water was 1.3% for 95%

species protection, where the observed ecotoxicity was likely to have been primarily due to

osmotic stress as a result of higher salinity of the CSG waters compared with surface

freshwater environments in the region. Freshwater organisms have been shown to be

sensitive to elevated EC levels as discussed in Section 2.1, particularly at levels observed in

the CSG waters tested (6,300 µS/cm). The ecotoxicity of the CSG water for each species is

presented in Table 4-1, for which the algal test showed the lowest IC10. The Hydra also

showed high sensitivity; which has been reported to be one of the most salt sensitive

invertebrates (Kefford et al 2007; Hart et al 1991). In contrast, the midge was not affected by

the CSG water.

Table 4-1: IC10 (expressed in %) for each species and Trigger Value (TV in % solution) for the CSG water

CSG

Wat

er

Du

ckw

ee

d G

row

th:

L. p

un

cta

ta

Juve

nile

Sh

rim

p S

urv

ival

:

C. n

iloti

ca

Dap

hn

ia S

urv

ival

:

C. d

ub

ia

Dap

hn

ia R

ep

rod

uct

ive

Imp

airm

en

t :

C. d

ub

ia

Alg

al G

row

th:

R. s

ub

cap

ita

ta

Hyd

ra P

op

ula

tio

n G

row

th:

H. v

irid

issi

ma

Mid

ge S

urv

ival

:

C. t

epp

eri

Fish

Lar

vae

Imb

alan

ce:

M. s

ple

nd

ida

Eco

toxi

city

TV

(%

)

RC Well 32 29 8 10 0.9* 4 100 27 1.3 CL: 0.20 – 15.30

Shading indicates the most sensitive species of the test suite. CL = Confidence limits. Trigger value as percent of CSG well

water was based on calculated SSDs using IC10 data converted to chronic ecotoxicity. * Indicate tests for which IC10 values

were not provided in the ecotoxicology laboratory reports due to low confidence limits. For these instances IC10s were

derived using a Log-Logit interpolation as described in Section 3.2.1. The model data and calculation for the tests are

provided in Appendix 4.


Hydrobiology

4.5 Conclusions

The main conclusions from Phase 1 of the program were:

The trigger values (TV) for protecting 95% of the species in the ecosystem was 1.3 %

for the CSG water;

The observed species sensitivity in the test organisms was likely due to osmotic

stress as a result of higher salinity of the CSG waters compared with surface

freshwater environments in the region; and

The most sensitive organism to the CSG water was the alga, and the least sensitive

was the midge.


Hydrobiology

5 PHASE 2: HYDRAULIC STIMULATION FLUIDS

5.1 Objectives

The main aim of this program was to understand the hazard potential of hydraulic

stimulation fluids associated with CSG waters to surface freshwater organisms in the region.

Therefore, the next step was the ecotoxicity testing of hydraulic stimulation fluids as whole

mixtures rather than individual chemical additives was undertaken.

The objective within this phase was to determine the ecotoxicity of the representative

hydraulic stimulation fluids constituted in source water, and thus representative of how

hydraulic stimulation fluids were constituted in the field.

Concentrations for chemical additives for two cross-linked fluids were selected based on

typical chemical additive mixtures used by Origin for stimulating wells in the Surat Basin in

2015. Both fluid systems were cross-linked with slightly different additive and delivery

mechanisms, which are further detailed below.

5.2 Composition of the hydraulic stimulation fluids

Based on the common hydraulic stimulation fluid chemistry used in the Surat Basin in 2015

and discussions with the stimulation service provider , the representative

concentrations for chemical additives for two cross-linked fluids were selected. The fluids

were consistent with the additives used for the operational well stimulation for Ramyard 24

and 23 for which flowback waters were tested in Phase 3 (Section 6).

Stimulation fluid RAM24: Cross-linked fluid - used to stimulate Ramyard 24; and

Stimulation fluid RAM23: Nitrogen foam cross-linked fluid– used to stimulate

Ramyard 23.

The two fluid systems have similar additives and the same chemical loading rates, with the

main difference being the additional use of a surfactant and the application of nitrogen gas

as a carrier to transport proppant into fractures in the nitrogen foam cross-linked fluid

system (RAM 23). Table 5-1 summarises the chemical additives used for each stimulation

fluid tested. The source water used for stimulating the wells was also considered in this

program, where Origin used water from Talinga water treatment facility for constituting the

fluids for well stimulation.


Hydrobiology

Table 5-1: Additives in the two cross-linked hydraulic stimulation fluids tested

Additive Additive Name Stimulation

Fluid RAM24

Stimulation Fluid

RAM23

Biocide BE-9

Guar WG-36

pH adjustment Acetic Acid 60%

Clay Control KCl

Cross-Linker BC140

Breaker GBW

Surfactant* HC2A x

Nitrogen gas* N2 x

* Additive only used in the nitrogen cross-linked fluid system (RAM23)

5.3 Methods

Hydraulic stimulation fluids were prepared under laboratory conditions for consistency in

fluid preparation. The selected hydraulic stimulation fluids were mixed using water from

Talinga water treatment facility (RO water with no addition of ions), which was used for

well stimulation.

The stimulation of CSG wells is implemented in a series of stepwise tasks. As a result, the

mixing procedure did not include the following components:

Proppants, which mainly consist of sand and ceramic, were considered a physical

component as they are primarily composed of silica and other inert materials, and

are therefore not likely to leach chemicals;

Ecotoxicity testing was carried out on broken cross-linked fluid rather than in gel

form. Breaking down the polymers prior to testing was necessary as unbroken cross-

linked fluids are designed to be viscous. The test organisms would not be able to

physically swim in the cross-linked mixtures in gel form, therefore the mixtures

required breakers to bring them back into a less viscous liquid form. Note that

breakers are added in such a way as to break the gel shortly after the stimulation has

occurred and the proppant has been transported into the seam, and before flowback

waters are extracted from the seam. Therefore, testing of broken gel is representative

of all potential pathways of exposure of surface freshwater organisms to hydraulic

stimulation fluids.

figure 26 pressure cement job equipment and setup (api, 2009)

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