Application of the Australian Guidelines for water ... · The Australian Guidelines for Water Recycling: Phase 2, Managed Aquifer Recharge were published on the website of the Environmental

June 2011

Application of the Australian Guidelines for Water Recycling Phase 2

Managed Aquifer Recharge to Perry Lakes Example Elise Bekele, Bradley Patterson, Anthony J. Smith

Water for a Healthy Country Flagship Report series ISSN: 1835-095X

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Citation: Bekele, E., Patterson, B., Anthony J. Smith (2011). Application of the Australian Guidelines for Water Recycling Phase 2 Managed Aquifer Recharge to Perry Lakes Example: Water for a Healthy Country National Research Flagship Report to the Department of Water of Western Australia.

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CSIRO advises that the information contained in this publication comprises general statements based on scientific research. The reader is advised and needs to be aware that such information may be incomplete or unable to be used in any specific situation. No reliance or actions must therefore be made on that information without seeking prior expert professional, scientific and technical advice. To the extent permitted by law, CSIRO (including its employees and consultants) excludes all liability to any person for any consequences, including but not limited to all losses, damages, costs, expenses and any other compensation, arising directly or indirectly from using this publication (in part or in whole) and any information or material contained in it.

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Cover Photograph:

Photograph of West Lake in Perry Lakes Reserve. Photograph courtesy of Dirk Slawinski, CSIRO. © 2010 CSIRO

Application of AGWR Phase 2 MAR to Perry Lakes Example Page i

CONTENTS Acknowledgments ................................... .................................................................. iii

Executive Summary ................................. .................................................................. iv

1. Introduction ...................................... .................................................................. 5

2. Step 1 – Decide whether the MAR guideline is approp riate ............................ 6

3. Step 2 – Provide project description .............. .................................................. 6

3.1. Location .................................................................................................................... 6

3.2. Project rationale and objectives ................................................................................ 8

3.3. State policies relating to the maintenance of water levels for wetland conservation 9

3.4. Project outline ........................................................................................................... 9

3.5. Soil and aquifer description .................................................................................... 11

3.6. Source water description ........................................................................................ 14

4. Step 3 – Decide whether the project meets the crite ria for a simplified assessment ........................................ .............................................................. 15

5. Step 4 – Conduct Stage 1 entry level assessment of viability ...................... 16

6. Step 5 – Identify environmental values of the aquif er and any intended uses of recovered water ................................... ............................................................ 17

6.1. Drinking water ......................................................................................................... 18

6.2. Industrial water and primary industries ................................................................... 18

6.3. Recreation and aesthetics ...................................................................................... 19

6.3.1. Perry Lakes ......................................................................................................... 19

6.3.2. Bold Park Reserve ............................................................................................... 19

6.3.3. Irrigation of public recreational open spaces and domestic irrigation .................. 20

6.4. Aquatic ecosystems ................................................................................................ 20

6.5. Cultural and spiritual issues .................................................................................... 21

7. Step 6 – Conduct Stage 1 entry level assessment of degree of difficulty ... 23

8. Step 7 – Identify investigations required ......... .............................................. 36

9. Step 8 – Conduct Stage 2 maximal risk assessment .. .................................. 36

10. Step 9 – Further requirements to address the guidel ines ............................. 44

Appendix A. Completed investigations to inform risk assessment ...................... 46

Appendix A1. Groundwater modelling .............................................................................. 46

Appendix A2. Source water quality assessment ............................................................... 52

i. Assessing water quality parameters ....................................................................... 52

ii. Assessing organic toxicants ................................................................................... 57

iii. Comparison of ambient groundwater, lake water and source water qualities ........ 60

iv. Salinity and sodicity evaluation ............................................................................... 65

Appendix B. Additional investigations ............. ....................................................... 67

i. Additional studies required ..................................................................................... 67

ii. Further modelling work required ............................................................................. 67

References ........................................ ........................................................................ 69

Application of AGWR Phase 2 MAR to Perry Lakes Example Page ii

LIST OF FIGURES Figure 1 Location of the proposed infiltration galleries for the Perry Lakes MAR scheme (modified after McFarlane et al. 2007). .................................................................................. 7

Figure 2 Location of the proposed infiltration galleries (red) superimposed on topographic contours at 1 m intervals for the Perry Lakes area. Topographic data supplied by the Department of Land Information and attributed by the Department of Environment for the Perth Groundwater Atlas (2004). ........................................................................................... 7

Figure 3 Map of Perry Lakes modified after Rich (2004) to show the location of the proposed infiltration galleries, bores used for irrigation and maintenance of water levels as of 2009/2010 (Ross Farlekas, Town of Cambridge, personal communication), and stormwater drains (Townley et al. 1995). .................................................................................................. 8

Figure 4 Perry Lakes aquifer recharge schematic, depicting (a) the water table gradient without MAR and drying of a lake, and (b) raising of the water table and regional groundwater flowing beneath and into a lake in response to a water table mound produced by recharge via infiltration galleries. This assumes that there is no flow of recycled water from the subsurface storage toward either of the lakes in Perry Lakes Reserve. ............................... 10

Figure 5 Aquifer section through Perry Lakes West, showing the stratigraphy and the maximum elevation of the water table in winter September 1997 (Rich, 2004). Refer to Figure 3 for the location of the transect line. ................................................................................... 12

Figure 6 Aquifer section through Perry Lakes East, showing the stratigraphy and the maximum elevation of the water table in winter September 1997 (Rich, 2004). Refer to Figure 3 for the location of the transect line. ................................................................................... 13

LIST OF TABLES Table 1 Perry Lakes MAR scheme proposed components ................................................... 11

Table 2 Subiaco WWTP secondary treated wastewater water quality data from Lugg & Western Australia Dept. of Health (2009) and Bekele et al. (2009). The data reported from the FIG study were for wastewater that passed through an Amiad-designed multi-media filter system. The wastewater for the PCRP study did not receive this treatment. N.D. = no data collected for the parameter indicated. N.A. indicates not applicable where only one sample was collected. .......................................................................................................... 15

Table 3 Perry Lakes entry level assessment part 1 - viability ............................................... 16

Table 4 Perry Lakes entry level assessment part 2 – degree of difficulty. The first two columns contain excerpts from Table 4.4 of the Phase 2 MAR guidelines in NRMMC-EPHC-NHMRC (2009). ................................................................................................................... 23

Table 5 Summary of Stage 2 investigations required at Perry Lakes ................................... 36

Table 6 Data summary to inform maximal risk assessment for Perry Lakes managed aquifer recharge proposal. The entries highlighted in green are those which have sufficient information for risk estimation at this time. ........................................................................... 38

Table 7 Qualitative measures of likelihood (NRMMC–EPHC–AHMC, 2006). ....................... 43

Table 8 Qualitative measures of consequences or impact (NRMMC–EPHC–AHMC, 2006). 43

Table 9 Qualitative risk estimation (NRMMC–EPHC–AHMC, 2006). .................................... 43

Table 10 Maximal risk assessment for several hazards only for the Perry Lakes managed aquifer recharge proposal. ................................................................................................... 44

Application of AGWR Phase 2 MAR to Perry Lakes Example Page iii

ACKNOWLEDGMENTS This environmental risk assessment based on the original Perry Lakes managed aquifer recharge proposal was supported by the Department of Water, Western Australia and the CSIRO Water for a Healthy Country Flagship. The authors express their gratitude to Dr Peter Dillon for his supportive advice and review comments on this report, Dr Don McFarlane for his review comments on an earlier draft of this report and Dr Declan Page for discussions on conducting risk assessments for water recycling projects.

This report was prepared for the Department of Water. The constructive feedback from the Water Science and the Water Recycling and Efficiency branches of the Department of Water and from Dr Don McFarlane from the CSIRO are gratefully acknowledged.

Application of AGWR Phase 2 MAR to Perry Lakes Example Page iv

EXECUTIVE SUMMARY This is a case study of an environmental risk assessment for a managed aquifer recharge (MAR) project that considers the environmental values of aquatic ecosystems in the context of infiltrating an aquifer with secondary treated wastewater. This report was commissioned by the Department of Water to assist future MAR proponents in undertaking environmental risk assessments in line with the Australian Guidelines for Water Recycling (AGWR) Phase 2 – Managed Aquifer Recharge (2009), particularly those that involve similar issues. It is intended to demonstrate the process and to explain how to interpret sections of the guidelines pertaining to environmental risks and to provide a step by step guide to regulators and future proponents on the environmental risk assessment requirements of the AGWR.

This report identifies data requirements, knowledge gaps and future work required to address these deficiencies.

The Australian Guidelines for Water Recycling: Phase 2, Managed Aquifer Recharge were published on the website of the Environmental Protection and Heritage Council (NRMMC-EPHC-NHMRC, 2009) in August 2009 as part of Phase 2 of the Australian Guidelines for Water Recycling (http://www.ephc.gov.au/taxonomy/term/39). The guidelines pertain to different sources of water, including treated sewage, stormwater, treated drinking water, and natural waters.

An environmental risk assessment was conducted based on a preliminary design proposal for managed aquifer recharge (MAR) via infiltration at the Perry Lakes. The Perry Lakes Reserve is in the Town of Cambridge in the suburb of Floreat, Western Australia. The site consists of a series of shallow wetlands above an unconfined aquifer composed of sand overlying limestone. The MAR proposal is to produce a water table mound by recharging the aquifer with secondary treated wastewater using a series of shallow infiltration galleries. The water table mound would serve as a partial hydraulic dam that would raise the water table beneath East and West Lakes in Perry Lakes Reserve. The intent is for recharged water to not enter the lakes. The proposal also involves irrigating the parkland around the lakes, using existing groundwater abstraction bores which are slotted towards the base of the aquifer.

The Perry Lakes project was selected as sufficient work had been completed to date to apply stages 1 (Entry level risk assessment) and 2 (Investigations and maximal risk assessment) of the AGWR. Further stages, such as identifying preventative measures are not part of this report. A public health risk assessment is also needed and would be assessed by the Department of Health, but was not commissioned as part of this report.

Perry Lakes Environmental Risk Assessment Page 5

1. INTRODUCTION In Western Australia, managed aquifer recharge (MAR) projects are primarily regulated by the state departments of Water and Health. As part of its approval process, the Department of Water requires application of the Australian Guidelines for Water Recycling (AGWR) through its Draft Managed Aquifer Recharge policy (Department of Water, 2009). It has also developed a draft approval framework for the use of non-drinking water in Western Australia (Department of Water, 2010).

This report was commissioned by the Department of Water to assist future MAR proponents in undertaking environmental risk assessments in line with the Australian Guidelines for Water Recycling (AGWR) Phase 2 – Managed Aquifer Recharge (NRMMC-EPHC-NHMRC, 2009), particularly those that involve ecosystem protection issues similar to those encountered at Perry Lakes.

This report is intended to demonstrate the process of applying the guidelines pertaining to environmental risks using Perry Lakes as a case study. It applies a step-by-step approach to the environmental risk assessment requirements of the AGWR.

The report demonstrates the Stage 1 entry level assessment and Stage 2 pre-commissioning investigations and maximal risk assessment. A public health risk assessment was not commissioned as part of this report.

The environmental risk assessment is based on a preliminary design proposal (McFarlane et al., 2007). The preliminary design forms the basis for this report and not the revised concept plan which was still in preparation at the time of this report.

Nine steps are used in this report in order to address the requirements of the MAR guidelines:

1. Confirm that the MAR guideline is appropriate. 2. Provide a project description. 3. Confirm that the project does or does not meet the criteria for a simplified

assessment. 4. Conduct part 1 of the entry level of assessment regarding the viability of the project. 5. Identify the environmental values of the aquifer and any intended uses of recovered

water. 6. Conduct part 2 of the entry level of assessment regarding the degree of difficulty of

the project. 7. Identify investigations that are required to address the criteria for the entry level

assessment. 8. Conduct the maximal risk assessment. 9. Further requirements to address the guidelines

Application of AGWR Phase 2 MAR to Perry Lakes Example Page 6

2. STEP 1 – DECIDE WHETHER THE MAR GUIDELINE IS APPROPRIATE

The following is an excerpt from Section 1.2.2 of the AGWR-MAR (NRMMC-EPHC-NHMRC, 2009):

These guidelines, used in conjunction with other NWQMS guidelines, cover all types of source water for managed aquifer recharge in urban and rural areas. Sources include:

• stormwater

• water recycled from wastewater treatment plants

• water from streams and lakes

• groundwater drawn from other aquifers or drawn remotely from the same aquifer

• water from drinking water distribution systems, including desalinated sea water.

These guidelines refer to managed systems with planned recharge and recovery. In all cases, human health and the environmental values of the aquifer, its connected ecosystems, and the water-quality requirements of the end uses are to be protected. These values are summarised in ARMCANZ–ANZECC (1994).

Based on this description, the MAR guideline is appropriate as the source water is recycled from a wastewater treatment plant.

3. STEP 2 – PROVIDE PROJECT DESCRIPTION The definition and purposes of MAR should be provided along with the components of the MAR system as discussed in Section 2.1.1 (Table 2.1) of the AGWR-MAR (NRMMC-EPHC-NHMRC, 2009).

The Perry Lakes MAR scheme is intended to recharge an unconfined aquifer with secondary treated sewage from the Subiaco Wastewater Treatment Plant.

3.1. Location The Perry Lakes Reserve is in the suburb of Floreat, 7 km west of Perth (Figure 1). Perry Lakes consists of a series of shallow wetlands above an unconfined aquifer. Groundwater enters these lakes from the northeast and discharges to the southwest. These are referred to as West Lake and East Lake, which cover areas of approximately 5.2 ha and 6.9 ha, respectively (Rich, 2004). The elevation of the land surface rises steeply west of the lakes. The natural land elevation is between 6 and 12 m AHD below the location of the proposed MAR project (Figure 2).


Perth

Camel Lake (dry)

(dry)

(mostly dry)

Figure 1 Location of the proposed infiltration galleries for the Perry Lakes MAR scheme (modified after McFarlane et al. 2007).

West Lake

East Lake

North

Scale Figure 2 Location of the proposed infiltration galleries (red) superimposed on topographic contours at 1 m intervals for the Perry Lakes area. Topographic data supplied by the Department of Land Information and attributed by the Department of Environment for the Perth Groundwater Atlas (2004).


3.2. Project rationale and objectives Groundwater levels have gradually fallen over large parts of the coastal plain under Perth (Smith et al., 2005) as a result of drier winters and extraction of groundwater for irrigation. Shallow through-flow wetlands such as Perry Lakes have dried and the availability of water for irrigation has been reduced (McFarlane et al., 2009).

The lakes receive storm water inputs and East Lake levels are maintained throughout the year by the Town of Cambridge, using groundwater to offset evaporation losses and lower groundwater levels (Rich, 2004).

Figure 3 depicts the locations of stormwater drains as identified in Townley et al. (1995), and bores that have been used in recent years to irrigate Perry Lakes Reserve and Alderbury Sport Ground and to artificially maintain water in East Lake. The groundwater abstraction bores used for irrigating parkland around the lakes are slotted towards the base of the aquifer. Down gradient of the MAR site there is Bold Park which consists of non-irrigated bushland on elevated limestone dunes. There are no production bores in Bold Park.

#43

#44

#176

LegendProposed location of infiltration galleriesStormwater drains (Townley et al. 1995)

As of 2009/2010Bores for irrigating Perry Lakes Reserveand Alderbury Sport GroundBores for artificial maintenance of East Lake

#2

#7

#8N

Bold Park

Figure 3 Map of Perry Lakes modified after Rich (2004) to show the location of the proposed infiltration galleries, bores used for irrigation and maintenance of water levels as of 2009/2010 (Ross Farlekas, Town of Cambridge, personal communication), and stormwater drains (Townley et al. 1995).

Adding groundwater to maintain Perry Lakes is getting increasingly expensive. West Lake can no longer be maintained and for this reason augmentation by the Town of Cambridge ceased in 2008. East Lake would be dry for most of the year without groundwater additions (Drummond, 2010; McFarlane et al., 2009)

The proposed MAR project aims to produce a water table mound by recharging the aquifer with secondary treated wastewater using a series of shallow infiltration galleries. The water table mound would serve as a partial hydraulic dam that would raise the water table beneath East and West Lakes in Perry Lakes Reserve. The intent is for recharged water to not enter the lakes.


The wetlands in Perry Lakes have not been identified as having high conservation value, such as those which are representative, rare, unique or important for conserving biological diversity. However, the wetlands in Perry Lakes have been ranked highly in terms of social values. In a study of 30+ groundwater-dependent features on the Gnangara Mound commissioned by the Department of Water, the social values of Perry Lakes wetlands were given the highest ranking by a range of stakeholders (Beckwith Environmental Planning, 2006). The rationale for this ranking was due to the wetland being an area that is heavily used by walkers and joggers that adjoins many active recreation facilities, popular with birders in the Perth area and adjacent to Bold Park – the largest remnant bushland in the Perth area (Beckwith Environmental Planning, 2006). In a survey of community attitudes and values toward different types of land use on the Gnangara Mound, Perth metropolitan residents ranked the importance of Perry Lakes as 6th (the highest rank was 1; the lowest rank was 12) (Tapsuwan et al., 2009a).

An analysis of proximity to urban wetlands on land values revealed the economic significance of having open water in Perry Lakes (Tapsuwan et al., 2007; Tapsuwan et al., 2009b). The capitalised amenity value of Perry Lakes to nearby properties was estimated at $54 million for existing homes nearby and an additional $25 million for proposed residential land redevelopment of Perry Lakes stadium adjacent to the wetlands (McFarlane et al., 2007).

3.3. State policies relating to the maintenance of water levels for wetland conservation

The practice of artificially supplementing the water levels in selected wetlands on the Gnangara Mound has been conducted to maintain their values and meet regulatory conditions (Beckwith Environmental Planning, 2006).

In setting environmental water provisions (EWPs), ecological values rather than social values are usually the primary consideration (Water and Rivers Commission, 2000). According to Western Australia’s water allocation planning framework described in Statewide Policy No. 5 (Environmental Water Provisions Policy for WA), the provision of water to sustain social values, “may be established as part of the EWP depending on their impact on natural ecosystems and the significance of the social value maintained by the water regime” (Water and Rivers Commission, 2000).

More recently, in the State Planning Policy No. 2.9 (Water Resources), where water resources have been identified as having significant economic, social, cultural and/or environmental values, these water resources should be protected, conserved and enhanced (Government of Western Australia, 2006). This policy applies to the Western Australian Planning Commission, the Department of Planning and Infrastructure and local government in undertaking plans that influence the use and development of land as it relates to water resources (Government of Western Australia, 2006). Another objective of this policy is to, “assist in ensuring the availability of suitable water resources to maintain essential requirements for human and all other biological life with attention to maintaining or improving the quality and quantity of water resources” (Government of Western Australia, 2006). With regard to implementation of this policy, for proposals involving local urban land use changes, the Western Australian Planning Commission on advice of the Department of Water is responsible for approving water management plans (Government of Western Australia, 2008).

3.4. Project outline The proposed source water is wastewater from the Subiaco Wastewater Treatment Plant, which receives secondary treatment via a biological activated sludge process.

Following secondary treatment, the wastewater could receive additional polishing via passage through Amiad multi-media filters if the risk assessment determines this is


necessary. This is considered a preventive measure that should be addressed in further stages that are not covered in this report.

For the proposed MAR scheme, reclaimed water would be pumped to a series of infiltration galleries. The dimensions of the infiltration galleries would be 1 m wide, 1 m deep and 1,300 m in total length. The galleries would be located hydraulically down-gradient from the lakes at a minimum distance of 75 m from the southern end of East Lake and a minimum distance of 100 m from the west side of West. The MAR scheme is intended to produce a water table mound or hydraulic barrier that would raise the water table beneath the lakes. The scheme relies on regional groundwater flowing continuously beneath and into the lakes to prevent back flow of treated effluent into the lakes. The volume of wastewater required to create the partial barrier that would allow regional groundwater levels to rise and fill the lakes is 5.3 ML/day or 1.9 GL/yr based on model predictions from a steady-state groundwater flow model as described in Appendix A1.

A schematic of the Perry Lakes MAR project is given in Figure 4. Only one lake is depicted for simplicity. A description of the components is provided in Table 1.

a) Without MAR

b) With MAR

Lake

Figure 4 Perry Lakes aquifer recharge schematic, depicting (a) the water table gradient without MAR and drying of a lake, and (b) raising of the water table and regional groundwater flowing beneath and into a lake in response to a water table mound produced by recharge via infiltration galleries. This assumes that there is no flow of recycled water from the subsurface storage toward either of the lakes in Perry Lakes Reserve.


Table 1 Perry Lakes MAR scheme proposed components

Component Perry Lakes MAR scheme

1. Capture zone Secondary treated sewage effluent from the Subiaco WWTP

2. Pre-treatment Pre-treatments are considered preventive measures that should follow the maximal risk assessment

3. Recharge Infiltration galleries ~ 1 m wide x 1 m deep x 1,300 m long

4. Subsurface storage Spearwood Sand and the unconfined Tamala Limestone which together constitute the Superficial Aquifer

5. Recovery None. Infiltration to create a hydraulic barrier to raise lake water level

6. Post-treatment Nil

7. End use Increase and maintain lake levels in Perry Lakes for social and environmental benefit; may have an impact on irrigation of Perry Lakes Reserve parkland and oval by the Town of Cambridge.

The galleries would be divided into 50 m long sections, each connected to a 200 mm delivery main. This will enable each section to receive different amounts of water as required and will enable sections to be individually maintained, for example, in case oxidizing and de-clogging measures are needed.

The proposal is based on the assumption that recharged water will not enter the lakes. If investigations demonstrate that wastewater enters the lakes, either directly or indirectly, the assessment would change substantially.

3.5. Soil and aquifer description The yellow Spearwood Sands consist of quartz grains coated with kaolin clays impregnated by goethite, an iron oxy-hydroxide. In measurements of septic tank performance around Perth, the goethite was found to have very high adsorption rates for phosphorus (Whelan and Barrow, 1984).

The Perry Lakes site is underlain by an unconfined aquifer consisting of the superficial Spearwood sands which extend to the surface and the underlying Tamala Limestone Formation. Minor clay lenses interspersed with sand exists beneath the lakes as shown in aquifer sections through East and West Lakes (Rich, 2004). The thickness of the top layer of sand ranges from 5 to 25 m, whereas the underlying Tamala Limestone ranges from 10 to 40 m (Drummond, 2010). Both the Spearwood sands and the Tamala Limestone are of Pleistocene age (Tapsell et al., 2003).


Figure 5 Aquifer section through Perry Lakes West, showing the stratigraphy and the maximum elevation of the water table in winter September 1997 (Rich, 2004). Refer to Figure 3 for the location of the transect line.


Figure 6 Aquifer section through Perry Lakes East, showing the stratigraphy and the maximum elevation of the water table in winter September 1997 (Rich, 2004). Refer to Figure 3 for the location of the transect line.


Tracer tests reveal that the horizontal hydraulic conductivity of the sands is 10 to 30 m/d, and up to 100 m/day for the limestone. Low conductivity clays are present in the sand and have produced perched remanent ponds (Rich, 2004). The transmissivity values of the entire aquifer vary from 700 to 2,200 m2/day.

The aquifer is unconfined and the hydraulic gradient is around 0.0014. In the vicinity of the proposed infiltration gallery, the maximum depth to the water table ranges from 3 to 9 m below the ground surface based on the difference between the natural surface topography (Figure 2) and estimates of the water table level at the end of summer (Department of Environment, 2004). A similar range in the depth to water was measured in bores located near the proposed infiltration galleries between May and October 2010 according to data from Drummond (2010).

Groundwater in the aquifer is aerobic with salinity in the range of 800 to 870 mg/L total dissolved solids (TDS). The mineralogy of the Tamala Limestone consists quartz sand and shell fragments that are weakly cemented by calcium carbonate (Davidson, 1995).

3.6. Source water description The reclaimed water source is wastewater from the Subiaco Wastewater Treatment Plant (WWTP) operated by the Water Corporation of Western Australia. The Subiaco WWTP treats domestic wastewater collected mainly from the Perth central metropolitan area (Water Corporation, 2009a).

The wastewater receives preliminary treatment involving screens to remove large material which is removed for disposal at a landfill site. Following the screening process, the wastewater flows through grit removal tanks to allow inorganic material to settle (Water Corporation, 2009a). Organic material remains in suspension. The next step is primary treatment whereby the flow enters sedimentation tanks and a raw sludge pumping system (Water Corporation, 2009a). The wastewater remains in the sedimentation tank until 90% of the settable solids settle out on the floor of the tanks as raw sludge (Water Corporation, 2009a). This material is then removed by mechanical scrapers and the primary treated wastewater flow to the secondary treatment process (Water Corporation, 2009a).

The secondary treatment process includes a conventional activated sludge process with biological nutrient removal (Water Corporation, 2009a). The primary treated wastewater is mixed with microbiological biomass in aeration tanks. Organic compounds in the primary treated wastewater are broken down by microbial activity (Water Corporation, 2009a).The mixture from the aeration tanks flows into sedimentation tanks and the sludge that settles from these tanks is continuously removed and returned to the aeration tanks to sustain the microbiological population (Water Corporation, 2009a). The overflow from the sedimentation tanks is the final wastewater that is suitable for ocean discharge (Water Corporation, 2009a). The majority of secondary treated wastewater is currently discharged to the Indian Ocean at an outlet located 1 km offshore and 10 m below the surface of the ocean (Water Corporation, 2009a).

In 2009, the Department of Health published a comprehensive report for the Premier’s Collaborative Research Program (PCRP) on the chemical and microbial characteristics of treated wastewater from three metropolitan wastewater treatment plants, including Subiaco (Lugg & Western Australia Dept. of Health, 2009). The Floreat Infiltration Galleries (FIG) study provides additional data on the source water quality. The FIG study used secondary treated wastewater from the Subiaco WWTP with additional treatment via passage through an Amiad-designed multi-media filter system (Bekele et al., 2009). As filtration is a preventive measure to reduce suspended solids and turbidity, one should be wary of considering these data and electrical conductivity because filtration probably have lowered these measurements as compared to unfiltered source water. The FIG study provided more source water data for a larger range of metals and metalloids which aided in filling gaps in the data collected for the PCRP study (Table 2). Data from the PCRP report and the FIG study are referred to in the entry level assessment (Table 4) and are used for the source


water quality assessment in Appendix A2. Nutrients and standard parameter data are given in Table 2.

Table 2 Subiaco WWTP secondary treated wastewater water quality data from Lugg & Western Australia Dept. of Health (2009) and Bekele et al. (2009). The data reported from the FIG study were for wastewater that passed through an Amiad-designed multi-media filter system. The wastewater for the PCRP study did not receive this treatment. N.D. = no data collected for the parameter indicated. N.A. indicates not applicable where only one sample was collected.

Parameter Data from PCRP study (Lugg & WA Dept of Health, 2009)

Data from FIG study (Bekele et al., 2009)

Number of Samples

Mean Standard Deviation

Number of

Samples

Mean Standard Deviation

Temperature (ºC) N.D. N.D. N.D. 53 24.0 3.7 pH N.D. N.D. N.D. 40 7.3 1.1

Suspended solids (mg/L) 1626 19 14.8 8 7.5 7.05

Total dissolved solids (mg/L) 203 813 316 20 755 179

Alkalinity (mg/L) 181 140 20 36 145 20 Biological oxygen demand (mg/L) 202 6.4 3.3 6 <5 0

Nitrate as N (mg/L) 220 6.23 1.95 42 2.16 1.41

Nitrite as N (mg/L) 219 0.33 0.27 N.D. N.D. N.D.

Ammonia (mg/L) 250 2.44 2.13 20 0.64 0.85 Organic nitrogen

(mg/L) 44 3.3 5.3 N.D. N.D. N.D. Total Kjeldahl

nitrogen (mg/L) 250 5.1 3.2 20 1.86 0.98 Total nitrogen

(mg/L) N.D. N.D. N.D. 22 4.28 2.16 Phosphate (mg/L) 1 0.11 N.A. N.D. N.D. N.D. Soluble Reactive

Phosphorus N.D. N.D. N.D. 42 6.3 3.3 Total phosphorus

(mg/L) 250 8.7 3.0 N.D. N.D. N.D. Total organic

carbon 1 9.0 N.A. 41 10.0 3.8 Dissolved organic

carbon 1 8.0 N.A. 14 10.9 2.4 Oil & grease 14 13.2 21.3 N.D. N.D. N.D.

4. STEP 3 – DECIDE WHETHER THE PROJECT MEETS THE CRITERIA FOR A SIMPLIFIED ASSESSMENT

The following is an excerpt from Section 4.2 of the AGWR-MAR (NRMMC-EPHC-NHMRC, 2009).

To be eligible for a simplified assessment, a managed aquifer recharge project would need to meet the following criteria:

• source water is roof runoff from a single dwelling

• recovered water is for irrigation or other non-drinking uses specified by the local authority


• an aquifer capable of storing additional water exists

• the aquifer

– has not been identified as being affected by industrial or agricultural contamination to an extent that precludes use

– is not used for drinking water supplies in the area, and is not capable of use as a drinking water supply based on ambient groundwater quality

– is confined and not artesian, or is unconfined and has a watertable deeper than 4 m in rural areas or 8 m in urban areas, or as otherwise specified by the local authority

The project is therefore not eligible for a simplified assessment as it does not use roof runoff as the source.

5. STEP 4 – CONDUCT STAGE 1 ENTRY LEVEL ASSESSMENT OF VIABILITY

This step involves completing a template for the viability assessment given in Table 4.3 in the AGWR-MAR (NRMMC-EPHC-NHMRC, 2009). If the answer to all of the questions given in Table 4.3 of Section 4.3.1 of the AGWR is ‘Yes’, then proponents may proceed to determine the degree of difficulty.

Table 3 Perry Lakes entry level assessment part 1 - viability

Attribute Answer

1. Intended water use

Is there an ongoing local demand or clearly defined environmental benefit for recovered water that is compatible with local water management plans?

Yes. Lake water level management is needed to prevent loss of existing wetland habitat and associated flora and fauna.

The current maintenance of artificial lake level by pumping groundwater into lakes is unsustainable due to a falling regional water table. An Environmental Management Plan commissioned by the Town of Cambridge recommended an investigation into the use of treated wastewater as a solution (PPK, 2000). The intent is to continue abstracting groundwater from existing bores in the unconfined aquifer at Perry Lakes Reserve for irrigation.

2. Source water availability and right of access

Is adequate source water available, and is harvesting this volume compatible with catchment water management plans?

Yes. Source water is available from the Subiaco WWTP and the plant produces approximately 60 ML/day. Recharging 5.3 ML/day would slightly reduce the volume of secondary treated wastewater discharged at ocean outfalls.

3. Hydrogeological assessment

Is there at least one aquifer at the proposed managed aquifer recharge site capable of storing additional water?

Yes. The Tamala Limestone is regionally known for its high transmissivity. The overlying Spearwood Sand is generally less transmissive but it contains goethite which is known to remove phosphorus.


Is the project compatible with groundwater management plans?

Yes. The Perry Lakes proposal had a conceptual review by the Department of Water (Water Corporation 2007). The project was cited as a case study in the State Water Recycling Strategy (Government of Western Australia, 2007). As part of the regional groundwater plan, the Town of Cambridge aims to reduce its reliance on pumping from the aquifer (Town of Cambridge, 2008). According to the Town of Cambridge, groundwater abstraction for irrigating Perry Lakes Reserve and Alderbury sportsground as well as water level management of East Lake totalled 347 ML/yr in 2009/2010 (Ross Farlekas, Town of Cambridge, personal communication). The proposed amount of recharge to the aquifer is approximately 5.6 times greater. Gnangara Sustainability Strategy identified the potential for recharge of Subiaco WWTP water (Gnangara Coordinating Committee, 2009). The proposal has also been cited in Water Forever as a possible pilot for wider scale adoption to address falling water levels if successful (Water Corporation, 2009b).

4. Space for water capture and treatment

Is there sufficient land available for capture and treatment of the water?

Yes. The proposed scheme uses an existing treatment plant and the preliminary design plan indicates sufficient land is available.

5. Capability to design, construct and operate

Is there a capability to design, construct and operate a managed aquifer recharge project?

Yes. The Town of Cambridge has engaged the services of consultants with expertise in hydrogeology, geotechnical design, and water-quality management. The project would be overseen by a Steering Committee involving people from the Water Corporation, the CSIRO and the Department of Water. There are sufficient resources for ongoing operation, maintenance and monitoring.

As part of the Western Australian Water Foundation project “Determining the Requirements for MAR in Western Australia”, prototype MAR infiltration galleries were established and monitored at the CSIRO within 1 km of the proposed Perry Lakes MAR site using secondary treated wastewater from the Subiaco WWTP followed by rapid sand filtration (Bekele et al., 2009). The Floreat Infiltration Galleries facility operated from October 2005 to December 2008. This allowed assessment of geochemical changes and fate of recycled water and its constituents in the aquifer.

As the answer to all questions in Table 3 is ‘yes’, assessment can proceed.

6. STEP 5 – IDENTIFY ENVIRONMENTAL VALUES OF THE AQ UIFER AND ANY INTENDED USES OF RECOVERED WATER


The National Water Quality Management Strategy (NWQMS) provides a framework to manage water quality protection of fresh and marine water bodies and defines environmental values as “particular values or uses of the environment that are important for a healthy ecosystem or for public benefit, welfare, safety or health and which require protection from the effects of pollution, waste discharges and deposits” (ANZECC–ARMCANZ, 2000). The strategy involves identifying the environmental values (EVs) that are to be protected in a particular water body and the spatial designation of the environmental values to identify where the values will apply (ANZECC–ARMCANZ, 2000). As stated in these guidelines, if there are multiple EVs, the more conservative of the associated guidelines should become the water quality objective.

The ANZECC-ARMCANZ (2000) guidelines recognise six environmental values:

• drinking water

• industrial water

• primary industries

• recreation and aesthetics,

• aquatic ecosystems,

• cultural and spiritual issues,

The three EVs highlighted above are relevant to the unconfined aquifer in the vicinity of the Perry Lakes MAR scheme.

6.1. Drinking water The area in the vicinity of Perry Lakes extending west-southwest to the Indian Ocean in the direction of groundwater flow is not designated as a Public Drinking Water Source Area (PDWSA). The nearest proclaimed areas for public drinking water are two small catchment areas surrounding Bold Park Bore No.1 Water Reserve and Bold Park Bore No. 2 Water Reserve. Both catchment areas are not in the vicinity of groundwater flow down-gradient from the proposed scheme. Bold Park Bore No.1 & 2 are artesian bores located less than 1 km from Mt Kenneth Reservoir, City Beach that were drilled to supplement surface water sources during times of peak demand. These are artesian bores that penetrate a confined aquifer such that the hydraulic head exceeds that in the superficial aquifer and would prevent contaminated water from entering; hence there is no possibility of contamination by the recharge plume. As drinking water source areas or proclaimed catchments are not present in the vicinity of groundwater flow down-gradient from the MAR scheme, the Drinking Water EV does not apply to the Perry Lakes scheme.

Given the information presented above, it appears that the drinking water EVs do not apply; however, this must be confirmed by modelling the groundwater flow directions (see Appendix A1).

6.2. Industrial water and primary industries To the best of our knowledge, there are no commercial or primary industries that rely on groundwater from the unconfined aquifer or underlying aquifers in the vicinity of the proposed MAR and the area extending hydraulically down-gradient from the site to the coast; therefore the Industrial Water EV and Primary Industries EV do not need protection. The primary industries category includes irrigation and general water uses in the context of agriculture and general farm use. Landscape irrigation will be covered under the recreation and aesthetics EVs.

Given the information presented above, it appears that the primary industries and industrial water EVs do not apply; however, this must be confirmed by modelling the groundwater flow directions (see Appendix A1).


6.3. Recreation and aesthetics The NWQMS guidelines intend that the Recreation and Aesthetics EV maintain water bodies to accommodate recreational activities such as swimming, boating, fishing, and the aesthetic appeal of the water bodies (ANZECC–ARMCANZ, 2000). Landscape irrigation of public recreational open spaces and from domestic wells is also included in this category (NRMMC–EPHC–AHMC, 2006).

6.3.1. Perry Lakes

According to an Environmental Management Plan for Perry Lakes Reserve, the lakes serve three main roles as:

• the focal point of a public recreation space;

• a habitat for water birds and aquatic animals such as turtles; and

• sumps for urban stormwater (PPK, 2000).

The recreational use does not include swimming, boating or fishing. The lakes are not fenced and human contact with the water is possible. The main concern for the Perry Lakes MAR scheme with regard to this environmental risk assessment is to protect the aesthetic quality of the water body for visual recreational use (no-contact activity) (ANZECC–ARMCANZ, 2000). This includes not altering the surface water bodies in any way that reduces their ability to support aesthetically valuable flora and fauna. According to the guidelines, the visual clarity and colour of water in the lakes must be protected such that

• the natural visual clarity should not be reduced by more than 20%;

• the natural hue of the water should not be changed by more than 10 points on the Munsell Scale;

• the natural reflectance of the water should not be changed by more than 50% (ANZECC–ARMCANZ, 2000).

Moreover, the NWQMS guidelines (2000) indicate that the visual impact of water bodies should be free from substances that produce undesirable colour or odour, and free of undesirable aquatic life, such as algal blooms, or dense growth of attached plants or insects (ANZECC–ARMCANZ, 2000). Nuisance organisms described in the guidelines include macrophytes, phytoplankton scums, filamentous algal mats, blue-green algae, sewage fungus, midge, aquatic worms and leeches, which should not be present in excessive amounts as these may influence the visual recreational value and/or endanger the health or physical comfort of people and animals (ANZECC–ARMCANZ, 2000). This includes people picnicking or walking near the shoreline.

As discussed in the modelling section (Appendix A1), migration of the recycled water up-gradient through the aquifer into either East or West Lake is not intended. If this assumption is correct, it is relatively unlikely that there will be any reduction in the visual clarity and colour of the water as the scheme involves regional groundwater backing up into the lakes to increase water levels and regional groundwater would flow naturally through the lakes under wetter climate conditions.

6.3.2. Bold Park Reserve

The proposed MAR would allow groundwater mixed with treated wastewater to flow under Bold Park. This reserve is on Crown land designated as an A-class reserve under the Land Administration Act 1997 and is managed by the State’s Botanic Gardens and Parks Authority. The Authority must comply with all relevant State and Commonwealth legislation and strategic policies based on the Botanic Gardens and Parks Authority Act 1998, which covers its functions relating to promoting recreation and tourism, and conserving biological diversity, landscape features and Aboriginal heritage. The relevant legislation also includes, but is not limited to, the Soil and Land Conservation Act (1945), Wildlife Conservation Act (1950) and the Environmental Protection and Biodiversity Conservation Act (1999). An A-


class reserve such as Bold Park is protected to prevent activities that adversely affect its ecosystems or landscape.

Camel Lake in Bold Park is designated as a seasonally waterlogged basin that has been dry since the 1980’s (Rich, 2004). The shortest distance between Camel Lake and the proposed infiltration galleries is approximately 500 m, northeast of Camel Lake (Figure 1).

Further modelling of groundwater flow and transport under transient conditions is needed to clarify water levels and migration of the wastewater plume in the down-gradient (west-southwest) direction relative to Perry Lakes. Constraints on water levels and rates of water level rise and fall at Camel Lake should be referred to the Botanic Gardens and Parks Authority for clarification as to whether the proposed MAR activities would contravene the management plan for Bold Park.

The intersection of groundwater flow paths with Camel Lake in Bold Park has not been investigated. The risk of breakthrough of high concentrations of nutrients in this dampland and the implications for excessive amounts of nuisance organisms on the visual recreational use and aesthetics also requires further consideration.

6.3.3. Irrigation of public recreational open space s and domestic irrigation

There are eight production bores surrounding Perry Lakes that are connected to a ring main and used by the Town of Cambridge to service the reserve and surrounding park grounds (PPK, 2000). At Alderbury sports ground, the turf being irrigated is kikuyu grass, whereas at Perry Lakes Reserve, the turf is kikuyu and common couch grass (Ross Farlekas, Town of Cambridge, personal communication). According to groundwater consumption records for 2009/2010, six of these bores are in use to irrigate the reserve, Alderbury sports ground and for water level management of East Lake and consumed a total of 347 ML/yr (Ross Farlekas, Town of Cambridge, personal communication). As shown in Figure 3, the bores located closest to the proposed location of the infiltration galleries are bores #43, #44 and #176, which are located less than 60 metres from the proposed galleries. Bore #44 intersects the southern end of the proposed galleries and would need to be decommissioned.

Groundwater flows from northeast to southwest relative to the proposed MAR scheme (Figure 1). There are private and Town of Cambridge abstraction bores in the unconfined aquifer located approximately 2 km to the west-southwest of the Perry Lakes site used for reticulation in the residential neighbourhood of south City Beach.

6.4. Aquatic ecosystems The objective of the aquatic ecosystem EV is to, “maintain and enhance the ‘ecological integrity’ of freshwater and marine ecosystems, including biological diversity, relative abundance and ecological processes” (ANZECC–ARMCANZ, 2000). Aquatic ecosystems consist of the animals, plants, and micro-organisms that live in water, and the physical and chemical environment and climate with which they interact (ANZECC–ARMCANZ, 2000). The aquatic ecosystem EVs for the Perry Lakes MAR scheme should consider:

• Groundwater movement to fresh water;

• Groundwater movement to the marine environment; and

• Groundwater dependent vegetation

Groundwater fauna or stygofauna have not been surveyed at the site. Stygofauna occur within the unconfined aquifer on the Gnangara Mound, but based on sparse sampling, the indications are that species richness is low (Bennelongia, 2008). The threats to stygofauna species and communities include loss of habitat due to lowering of water tables, increases in nutrients and pollutants (Bennelongia, 2008). While it is likely that stygofauna will be low in species richness and abundance based on studies on the Gnangara Mound, this information is lacking for the unconfined aquifer at this site and represents a knowledge gap.


Before stygofauna are dismissed as groundwater dependant ecosystem at risk from this MAR proposal for Perry Lakes, further advice should be sought from experts (Dillon et al., 2009; NRMMC-EPHC-NHMRC, 2009).

Perry Lakes should be considered a disturbed aquatic ecosystem. Historical records indicate that Perry Lakes was originally part of a natural wetland system, but the identity of the original aquatic flora of the lakes is unknown (PPK, 2000). The water table has decreased significantly and remained low over such an extended period that weeds have invaded certain parts. The lakes are used as sumps for urban stormwater (PPK, 2000). Despite the use of the lakes as a stormwater sump, the MAR scheme does not intend for secondary treated wastewater to flow either directly or indirectly into the lakes. The density of algal growth in the lakes surveyed by (PPK, 2000) indicated moderate levels of nutrient enrichment. Aerial photographs taken before 1962 suggest that the lakes supported fringing vegetation including paperbarks, sedges and reeds as well as terrestrial species within the lakes, but land clearing since before the 1930’s changed the natural wetland system (Dames and Moore, 1992).

Comprehensive baseline surveys of aquatic fauna and flora are needed for Perry Lakes Reserve near the proposed site to determine whether there are particular species of high conservation value. Declining water levels are an immediate threat to habitat for water birds and turtles (PPK, 2000). According to a survey conducted by Dames and Moore (1992), very little aquatic flora was found in the lakes. Some of the existing flora surveyed by Dames and Moore (1992) when the lake was temporarily inundated by high water, were semi-aquatic species or terrestrial species. Until more recent baseline survey information is available, it remains unclear whether permanent inundation of the lakes will be detrimental to species that rely on the lakes. In these areas where the MAR scheme intends to produce rising water levels, the dominant flora include Eucalyptus (PPK, 2000) as well as other trees that should be surveyed. An assessment of ecosystems potentially impacted by MAR operations is required. If the vegetation or ecology is dependent on groundwater, then ecosystem support is an environmental value of the aquifer.

There is sparse information on fauna in Perry Lakes Reserve. PPK (2000) indicate that there had been no recorded fauna surveys conducted at the time of their environmental management report, although they did provide results from an earlier report by Dames and Moore (1992), which showed a number of frog species, the abundance of long-necked Swamp Turtles and differences in aquatic invertebrate species between the two lakes. As indicated by PPK (2000), there were earlier studies of water birds found in Perry Lakes, but none of the species that were surveyed were protected under the Wildlife Conservation Act (PPK, 2000).

The Botanic Gardens and Parks Authority, which manages Camel Lake in Bold Park should be consulted regarding restoration of this wetland. The proposed MAR scheme could potentially inundate this area located approximately 500 m west of East Lake which is designated as a seasonally waterlogged basin.

Groundwater movement to the marine environment is another aquatic ecosystem EV to consider. Although the Subiaco WWTP discharges secondary treated wastewater at an ocean outfall near the predicted pathway for submarine discharge of groundwater down-gradient from the proposed galleries, the proximity to coastal habitats requires further consideration because of the potential for increased concentrations of nutrients and organic chemicals in the near-shore waters.

6.5. Cultural and spiritual issues The NWQMS guidelines recognise the significance of cultural and spiritual values, particularly for indigenous peoples. No specific guidance for protection of these values is provided, but the NWQMS indicates that planning and management of water resources must consider cultural issues (ANZECC–ARMCANZ, 2000).

According to a study into Aboriginal cultural values associated with groundwater-related environmental features on the Gnangara Mound, the Nyungar people have close historical


associations with lakes, rivers, wetlands, swamps and springs on the Mound, including Perry Lakes and the whole of Bold Park which are registered sites with the Department of Indigenous Affairs (Estill & Associates, 2005). There are historical accounts of turtle hunting and uses of other foods at Perry Lakes. Bold Park is a registered site due to mythological significance as well as historical camping and hunting (Estill & Associates, 2005).

The cultural value of Perry Lakes and possibly Camel Lake in Bold Park are directly related to groundwater in the unconfined aquifer. As discussed in the groundwater modelling section, the infiltration of secondary treated effluent will produce a partial hydraulic dam that will increase groundwater levels and impact lake levels in Perry Lakes. Although effluent is not intended to flow into Perry Lakes, effluent diluted with regional groundwater will flow down-gradient below Bold Park and potentially into Camel Lake. Aboriginal stakeholders will need to be consulted in relation to the management of cultural heritage and groundwater replenishment with secondary treated effluent. Actions that preserve and restore wetlands and water flow to their natural state are likely to receive Aboriginal support (Estill & Associates, 2005); however there is an incomplete understanding of the impact of replenishing the aquifer with secondary treated effluent on the cultural heritage of Aboriginal people. The Cultural and Spiritual EV requires further consideration for the Perry Lakes MAR scheme.


7. STEP 6 – CONDUCT STAGE 1 ENTRY LEVEL ASSESSMENT OF DEGREE OF DIFFICULTY This step involves completing a template for the degree of difficulty assessment given in Table 4.4 of the AGWR-MAR (NRMMC-EPHC-NHMRC, 2009) by answering 14 questions on technical and operational constraints. According to the AGWR, this will, “identify, using only rudimentary information, the likely degree of difficulty of the managed aquifer recharge project; this will inform the extent of investigations and level of operational expertise likely to be required at stage 2” (NRMMC-EPHC-NHMRC, 2009).

Table 4 Perry Lakes entry level assessment part 2 – degree of difficulty. The first two columns contain excerpts from Table 4.4 of the Phase 2 MAR guidelines in NRMMC-EPHC-NHMRC (2009).

Information required for assessment Questions and i ndicators of degree of difficulty

Perry Lakes answer and discussion, further investig ations

1 Source water quality with respect to environmental values “Where multiple samples are available, the highest concentration of each analyte should be used in the evaluation, unless there is justification that events resulting in those values will be prevented when the MAR project is established. • In the absence of water-quality data from actual source water, data may be used from existing, similar MAR projects that use the same type of source water and recharge the same aquifer. • In the absence of either of the above data sources, generic data from Australian water recycling guidelines may be used, as follows: – for stormwater; Appendix 2 of NRMMC– EPHC–NHMRC (2009) gives generic data on concentrations of selected hazards in stormwater from roof catchments and urban catchments; in the absence of other information, use 95 percentile data

“Q1. Does source water quality meet the water-quality requirements for the environmental values of ambient groundwater? (Note: environmental values of water are listed in Table A1.1 along with a reference to water-quality criteria for each.) If the answer is ‘Yes’, a low risk of pollution is expected. This is a necessary, but not sufficient, condition for low risk. If the answer is ‘No’, a high maximal risk is likely. Stage 2 investigations are likely to be necessary to assess preventive measures to reduce the risk of groundwater contamination beyond the attenuation zone (and the size of the attenuation zone). ”

No. The environmental values of ambient groundwater to be protected are:

- Aquatic ecosystems o Perry Lakes and Camel Lake o Marine ecosystems

- Recreation & aesthetics o Perry Lakes and Bold Park Reserves o Public open space irrigation o Irrigation from domestic wells

- Cultural and spiritual issues

Appendix A describes investigations that have been completed (i.e. groundwater modelling and source water quality assessment), but these highlight that further work is needed as described in Appendix B.


Information required for assessment Questions and i ndicators of degree of difficulty

Perry Lakes answer and discussion, further investig ations

– for treated wastewater; maximum concentrations detected in secondary treated wastewater may be used as a starting point and the Phase 1 guidelines give generic data (Table 4.10); these data range from wastewater that has been treated in water reclamation plants (minimum value) to raw secondary treated effluent (maximum value). • Assessment of quality variability and factors affecting quality are deferred to the maximal risk assessment.” 2 Source water quality with respect to recovered water end-use environmental values “If the source water does not meet the water quality requirements for the environmental values of intended end uses of recovered water, then there is a reliance on attenuation of hazards within the subsurface.”

“Q2. Does source water meet the water quality requirements for the environmental values of intended end uses of water on recovery?

If the answer is ‘Yes’, a low risk of pollution of recovered water is expected. However, this is not a sufficient condition for low risk due to aquifer reactions.

If the answer is ‘No’, a high maximal risk is likely. Expect Stage 2 investigations to assess this risk.”

No.

A source water quality assessment is described in Appendix A2. As there are multiple EVs, the more conservative of the associated guidelines is the water quality objective. In this case study, the guidelines for protecting aquatic ecosystems are generally more conservative than for irrigation. The answer is unknown because there is insufficient information on the plant species. A comprehensive survey of existing flora is needed along with their toxicity levels for different water quality parameters.


Information required for assessment Questions and i ndicators of degree of

difficulty Perry Lakes answer and discussion, further investig ations

3 Source water quality with respect to clogging

• “Where source water quality is poor and soil or aquifer are fine-grained, clogging of the infiltration basin and gallery or recharge well is likely to occur, unless the water is pretreated before recharge.

• Clogging is most prevalent when water contains moderate or high levels of suspended solids or nutrients, such as nitrogen or labile organic carbon.

• Clogging can also occur when oxygenated water is introduced into an aquifer that contains iron. If the soil or aquifer are coarse grained or contain macropores, clogging with such waters is less likely, but the risk of pollution of groundwater is high (as covered in Q1 and Q2).

Lack of evidence of clogging is insufficient to indicate that risk of pollution is low, even in fine-grained media.”

“Q3. Does source water have low quality, for example:

• total suspended solids >10 mg/L

• total organic carbon >10 mg/L

• total nitrogen >10 mg/L?

Also, is the soil or aquifer free of macropores?

If the answer is ‘Yes’, there is a high risk of clogging of infiltration facilities or recharge wells. Pretreatment will need consideration regardless of answers to Q1 and Q2.

If the answer is ‘No’, a lower risk of clogging is expected. However, this is not a sufficient condition for low risk, due to dependence of clogging on aquifer characteristics that would be revealed by stage 2 investigations.”

Yes. Based on the available source water data, the average concentration of suspended solids is 19 mg/L (PCRP study by Lugg & Western Australia Dept. of Health, 2009) and the 95th percentile value for total organic carbon is 15 mg/L (FIG study by Bekele et al. 2009). Total nitrogen concentrations in source water are <10 mg/L. The potential for macropores has not been assessed, but short-circuiting of flow through solution features or weakly cemented sections of the carbonate aquifer is likely. Clogging of the infiltration gallery is possible unless the water is pre-treated before recharge. Based on this, further studies would be required. Adaptive management of the scheme will be required to deal with clogging, if and when it arises.




4 Groundwater quality with respect to recovered water end-use environmental values

• “Where samples are available, the highest parameters detected in each sample should be used in the analysis; unless there is justification that events resulting in those values will be prevented when the MAR project is established.

• In the absence of data on groundwater quality from the proposed site, data from nearby wells in the same aquifer may be used.”

“Q4. Does ambient groundwater meet the water quality requirements for the environmental values of intended end uses of water on recovery?

If the answer is ‘Yes’, a low risk of inadequate recovery efficiency is expected.

If the answer is ‘No’, some risk of inadequate recovery efficiency is expected.

See Table A1.2 for degree of difficulty expected.”

Yes. The Town of Cambridge artificially maintains lake levels in the summer by pumping groundwater into the lakes. Groundwater also supports irrigation.

No further investigation is required because Perry Lakes is recharged naturally by regional groundwater and stormwater and has in the past been replenished by ambient groundwater to maintain lake levels.




5 Groundwater and drinking water quality

• “The environmental values of the aquifer need to be defined by the relevant authority. These will depend on the ambient groundwater quality and any groundwater-affected ecosystems, and as identified in the NWQMS Groundwater Protection Guidelines (ANZECC–ARMCANZ 1995)

• Setting these values involves a stakeholder consultation process, and in practice will possibly be related to groundwater allocation planning processes

• In the event of an absence of defined environmental values (for entry-level assessment purposes), all environmental values that are met by the native groundwater quality need to be protected. Such environmental values may include:

raw water for drinking supplies

irrigation

aquaculture, recreation or livestock water

support of aquatic ecosystems with various conservation values

The water quality requirements for these environmental values are referenced in Table A1.1.”

“Q5. Is either drinking water supply, or protection of aquatic ecosystems with high conservation or ecological values, an environmental value of the target aquifer?

If the answer is ‘Yes’, there is a high risk of groundwater pollution if recharged by water.”

“If the answer is ‘No’, a low risk of groundwater pollution is expected. However, this is not a sufficient condition for low risk.

For a broader view on this topic for the spectrum of environmental values, see Table A1.2.”

Yes. Protection of aquatic ecosystem with high conservation or ecologic values is an environmental value of the target aquifer with regard to Bold Park.

In the case of Perry Lakes Reserve, disturbed ecosystem conditions exist and the level of disturbance (slightly-to-moderately disturbed versus highly disturbed) will dictate the magnitude of guideline trigger values as per the percentage of species expected to be protected. See Appendix A2 and Table A5 for a comparison of ambient groundwater from the aquifer and lake water quality data.




6 Groundwater salinity and recovery efficiency

• “If native groundwater has high salinity, its proportion that can be present as a mixture with source water in recovered water is limited

• At such sites, density affected flow may also occur. Fresh recharge water can form a lens above the native saline groundwater, making recovery difficult and reducing recovery efficiency (ie the volume of recovered water meeting the environmental values for its intended uses as a proportion of the volume of recharged water)”

“Q6. Does the salinity of native groundwater exceed (a) 10 000 mg/L or (b) the salinity criterion for uses of recovered water?

If the answer to both parts of the question is ‘Yes’, there is a high risk of achieving only low recovery efficiency. Aquifer hydraulic characteristics, especially layering within the aquifer will need careful examination in Stage 2.

If the answer is ‘Yes’ only to Part (b), then a moderate risk of low recovery efficiency is expected. However, this is not a sufficient condition for low risk (eg in brackish aquifers with high rates of ambient lateral flow).

If the answer is ‘No’ to both parts of the question, there is a low risk of low recovery efficiency.”

No. No further investigation is needed.




7 Reactions between source water and aquifer

• “Reactions between source water and aquifer minerals may result in deterioration of water quality for recovered water, and possibly for water in the aquifer beyond the attenuation zone; or cause excessive clogging or dissolution of the aquifer.

• A full evaluation may be undertaken in Stage 2, but a simple indicator of the likelihood of potential problems at entry-level stage is to note the extent of contrasts between quality of source water and native groundwater.”

“Q7. Is redox status, pH, temperature, nutrient status and ionic strength of groundwater similar to that of source water?

If the answer is ‘Yes’, a low risk of adverse reactions between source water and aquifer is expected. However, this is not a sufficient condition for low risk.

If the answer is ‘No’, a high risk of adverse reactions between source water and the aquifer is possible, and will warrant geochemical modelling in Stage 2 (refer to sections 5.2, 5.4 and 6.1).”

No. Ambient groundwater and the source water have differing nutrient conditions. Table A5 in Appendix A2 provides a comparison of ambient groundwater and source water qualities.

The intent is to evaluate the potential reactions between the source water and aquifer that could lead to excessive clogging, dissolution of the aquifer, deterioration of water quality for recovered water or groundwater further beyond the attenuation zone. The likelihood of potential problems from adverse reactions cannot be fully assessed without a better understanding of ambient groundwater. The issues that should be further investigated are the potential for clogging by iron, discoloration of lake water quality by iron, dissolution of the carbonate aquifer, and mobilisation of trace ions. A study by PPK (2000) noted that further investigations into heavy metals contamination may be required as there were moderate to high concentrations of lead and moderately high zinc concentrations recorded in samples of lake sediments (PPK, 2000). Geochemical modelling should be conducted using ambient groundwater data collected from the site.

Based on this, further studies are required. This will include geochemical modelling.




8 Proximity of nearest existing groundwater users, connected ecosystems and property boundaries

• “Proximity of nearest existing groundwater users and groundwater-connected ecosystems is likely to influence the extent of investigations required in Stage 2.

• Typically, attenuation zones will have aquifer residence times of up to a year.

• If property boundaries are close to the MAR site, then the attenuation zone may extend beneath a neighbouring property.

Groundwater pressure effects in confined aquifers due to MAR may propagate over considerably longer distances than water quality effects.”

“Q8. Are there other groundwater users, groundwater–connected ecosytems or a property boundary near (within 100–1000 m) the MAR site?

If the answer is ‘Yes’, a high risk of impacts on users or ecosystems is possible, and this will warrant attention in Stage 2.

If the answer is ‘No’, a low risk of impacts on users or ecosystems is likely. However, this is not a sufficient condition for low risk.”

Yes. A high risk of impacts on users and ecosystems is possible given the proximity of the site to these boundaries.




9 Aquifer capacity and groundwater levels

• “Groundwater mound height induced by MAR depends on aquifer hydraulic properties, size of recharge area and recharge rate.

• Mounding is normally calculated in Stage 2 when aquifer properties are measured. However, excessive mounding can cause:

waterlogging

soil heave

flooding of below-ground infrastructure

salt damp

soil salinisation

• Hence, unconfined aquifers with shallow watertable sites are generally unsuitable as storage targets for large-scale recharge projects.

For confined artesian aquifers, care needs to be taken against overpressurisation, and to seal existing wells that might otherwise start to flow.”

“Q9. Is the aquifer confined and not artesian? or is it unconfined, with a watertable deeper than 4 m in rural areas or 8 m in urban areas?

If the answer to either part of the question is ‘Yes’, a low risk of water logging or excessive groundwater mound height is expected. However, this is neither a necessary nor a sufficient condition for low risk.

If the answer to both parts of the question is ‘No’, a high risk of water logging or excessive groundwater mound height is expected. However, Stage 2 investigations may reveal that risk is acceptable. “

No – The aquifer is unconfined and the water table is shallower than 8m (urban area). Further studies will therefore be required. Transient groundwater flow modelling is required to investigate issues related to aquifer capacity. See Appendix B.




10 Protection of water quality in unconfined aquifers

• “If the aquifer is unconfined and the intended recovery is for drinking water supplies, then overlying land and waste disposal (including intensive horticulture and septic tanks) should be managed carefully or precluded from the groundwater capture zone.”

“Q10. Is the aquifer unconfined, with an intended use of recovered water that includes drinking water supplies?

If the answer is ‘Yes’, a high risk of groundwater contamination from land and waste management.

If the answer is ‘No’, there is a lower risk of groundwater contamination from land and waste management.”

No. Drinking is not an intended use. There are two bores (Bold Park Bore No. 1 and No.2) that serve to supplement surface water sources for Mt Kenneth Reservoir, City Beach during times of peak demand, but the potable source is well confined in the Yarragadee aquifer.

11 Fractured rock, karstic or reactive aquifers

• “If the aquifer is fractured rock or karstic, the ability to recover stored water will require evaluation, especially if the ambient groundwater is saline, or hydraulic gradient is steep.

Provision will also need to be made for a larger attenuation zone, due to more rapid migration of recharge water from the recharge area.”

“Q11. Is the aquifer composed of fractured rock or karstic media, or known to contain reactive minerals?

If the answer is ‘Yes’, a high risk of migration of recharge water is expected. There is a need for an enlarged attenuation zone, beyond which pre-existing environmental values of the aquifer are to be met. Dissolution of aquifer matrix and potential for mobilisation of metals warrant investigation in Stage 2.

If the answer is ‘No’, a low risk of the above is expected. However, this is not a sufficient condition for low risk.”

Yes. This will require further investigation. The intent of this question is to determine if karst features or fractures in the aquifer are present which would adversely impact on the ability to recover stored water and/or impact on the size of the attenuation zone due to preferential flow paths. Although the proposed scheme does not intend to recover water, the presence of karst or fractures is potentially problematic because a highly transmissive aquifer will not form a water table mound or subsurface hydraulic dam to raise regional groundwater levels to intersect Perry Lakes and the travel time of water to the nearest users and to the ocean could be shorter than otherwise expected. Numerous caves have been documented within the Tamala Limestone in the Perth metropolitan area. A “buried pinnacle landscape” (solution pipes filled and re-cemented) was revealed from drilling the south side of Perry Lakes (Rich, 2004), but no fractures or karst have been identified at Perry Lakes. Pumping tests should be conducted to determine aquifer characteristics near the proposed site of the infiltration galleries.




12 Similarity to successful projects

• “A founding principle of MAR is that all validation and verification monitoring data should be in the public domain, and include sufficient operational data to enable accurate interpretation.

• This information is of value for future MAR projects, for improving design and operation and reducing costs and further refinement of these guidelines.

A national or state repository for these data should be accessible for proponents.”

“Q12. Has another project in the same aquifer with similar source water been operating successfully for at least 12 months?

If the answer is ‘Yes’, validation and verification data from the existing projects needs to be taken into account when designing the current project, in the Stage 2 investigations, and in subsequent risk assessments.

If the answer is ‘No’, all uncertainties are likely to need to be addressed in the Stage 2 investigations.”

Yes, the Floreat Infiltration Galleries (FIG) was operated from October 2005 to December 2008 for the Water Foundation project, “Determining Requirements for MAR in Western Australia”. Clogging with plant roots for one of the gallery designs became problematic and the proposed MAR at the Perry Lakes site would need to consider recommendations of improved gallery design to avoid clogging with plant roots. The source water for the FIG was secondary treated wastewater from the Subiaco WWTP with additional treatment by passage through rapid sand filters.




13 Management capability

• “A proponent new to MAR operation needs to gain appropriate expertise in parallel with Stage 2 investigations, to demonstrate a low level of residual risk for the precommissioning risk assessment.”

“Q13. Does the proponent have experience with operating MAR sites with the same or higher degree of difficulty (see Table A1.2), or with water treatment or water supply operations involving a structured approach to water quality risk management?

If the answer is ‘Yes’, there is a low risk of water quality failure due to operator experience.

If the answer is ‘No, there is a high risk of water quality failure due to operator inexperience. The proponent is recommended to gain instruction in operating such systems (eg a MAR operator’s course or aquifer storage and recovery course) or engage a suitable manager committed to effective risk management in parallel with Stage 2, to reduce precommissioning residual risks to low.”

No. An operator/manager of the scheme was not formally decided at the time of writing this report. However, the Water Corporation along with researchers at the CSIRO are heavily involved and has extensive experience with MAR operations. This would be resolved before the scheme could be made operational.




14 Planning and related requirements

• “Proximity of nearest neighbour

• Provision for safe public access or exclusion

• Dimensions and slopes of water holding structures

• Location and dimensions and design of any buildings or engineering structures,

• Method by which power will be brought to site and water connections

• Nuisance insect abundance before and after construction and proposed control measures

• Noise emissions of any mechanical plant and abatement measures

• Earthmoving and construction plans and measures for dust and noise control

• Provision of information to neighbours concerning the development

• Information to address other provisions of planning and development regulations within the relevant jurisdiction”

“Q14: Does the proposed project require development approval; is it in a built up area; built on public, flood-prone or steep land; close to a property boundary; contain open water storages or engineering structures; likely to cause public health or safety issues (e.g. falling or drowning), nuisance from noise, dust, odour or insects (during construction or operation), or adverse environmental impacts (e.g. from waste products of treatment processes)?

If the answer is ‘Yes’ to any of these, a development approval process will require that each potential issue is assessed and managed. This may require additional information and steps in design.

If the answer is ‘No’, the process for development approval, if required, is likely to be considerably simpler.”

Yes – the project will need approvals. It is located in a park/reserve area on public land, adjacent to an area to be extensively redeveloped for residential properties. Public health, safety and nuisance issues will need to be considered, but resident surveys demonstrate a strong desire for open water (McFarlane et al. 2007 – Risk Register). The project will need to be assessed under the Draft Approval Framework for the Use of Non-drinking Water in Western Australia (Department of Water, 2010).


8. STEP 7 – IDENTIFY INVESTIGATIONS REQUIRED The Stage 1 degree of difficulty assessment reveals the requirement for additional investigations for eleven of the fourteen criteria, indicating a relatively high level of difficulty for the proposed project. A summary of the Stage 2 investigations required are provided in Table 5.

Table 5 Summary of Stage 2 investigations required at Perry Lakes

Issue Investigations required at Stage 2 1 Source water quality with respect to

groundwater environmental values Water quality evaluation, particularly to assess seasonal variations in nutrients and ascertain water quality targets for ecosystem support.

2 Source water quality with respect to recovered water end use environmental values

Source water quality evaluation

3 Source water quality with respect to clogging

Clogging evaluation

5 Groundwater and drinking water quality Groundwater quality evaluation to assess risk to connected high-value ecosystems

7 Reactions between source water and aquifer

Geochemical evaluation; fate of recycled water trace organics

8 Proximity of nearest existing groundwater users, connected ecosystems and property boundaries

Groundwater flow and mass transport modelling

9 Aquifer capacity and groundwater levels

Evaluate potential for waterlogging and excessive groundwater mound height

11 Fractured rock, karstic or reactive aquifers

Geochemical evaluation

12 Similarity to successful projects Conduct trial to determine how to operate effectively.

13 Management capability Identify manager with competencies or train them at other MAR sites and on water quality risk management.

14 Planning and related requirements As required by legal approval processes

The studies that have been completed are described in Appendices A1 and A2. At this stage proponents should discuss the scope of studies required with the regulators. As described in the aquatic ecosystem EVs section, Perry Lakes should be considered a disturbed aquatic ecosystem, but the level of disturbance (i.e. slightly-to-moderately disturbed versus highly disturbed) should be decided in consultation with the Department of Water and the Department of Environment and Conservation (wetlands of high conservation value or RAMSAR). For the purposes of this case study, Perry Lakes is considered to have slight-to-moderately disturbed ecosystem conditions according to the criteria described in Chapter 3 (Aquatic Ecosystems) of ANZECC-ARMCANZ (2000). Trigger values for this level of ecosystem conditions were used accordingly to conduct the source water quality assessment in Appendix A.

9. STEP 8 – CONDUCT STAGE 2 MAXIMAL RISK ASSESSMENT The process of conducting the maximal risk assessment for the Perry Lakes scheme involved considering each of the key hazards outlined in Table 5.1 in the AGWR-MAR (NRMMC-EPHC-NHMRC, 2009). This list includes hazards that are known to occur or may be potentially found at the MAR site and include the following:

1. Pathogens 2. Inorganic chemicals


3. Salinity and sodicity 4. Nutrients: N, P, organic carbon 5. Organic chemicals 6. Turbidity and particulates 7. Radionuclides 8. Pressure, flow rates, volumes and groundwater levels 9. Contaminant migration in karstic aquifers 10. Aquifer dissolution 11. Aquifer and groundwater-dependent ecosystems 12. Energy and greenhouse gas considerations

No additional hazards were identified for this project.

This report was commissioned to examine hazards to the environment and does not include hazards to human health. Risk assessments should be undertaken with respect to microbial hazards to human health for projects involving human exposure to treated wastewater. As discussed in the Phase 1 guidelines (NRMMC–EPHC–AHMC, 2006), chemical hazards pose a greater risk to the environmental than microbial hazards, but there are emerging areas of concerns regarding microbial hazards (e.g. transfer of antibiotic resistant bacteria through waste to the environment). Environmental impacts of microorganisms from treated wastewater have not been identified in the guidelines at the time of writing this report, thus the focus is on chemical hazards to the environment. It should be noted that microbial pathogens exceed trigger values for irrigation as indicated in Appendix A2 (Table A3).

As there is a considerable amount of information to consider in conducting the risk assessment, the first step was to tabulate the hazards with respect to the environmental endpoints and conduct a data summary (Table 6). This involved determining whether each hazard was relevant for each particular endpoint, whether information was lacking, and whether trigger values were exceeded where there was sufficient information. The environmental endpoints and intended uses in Table 6 are those that were identified in Section 6. The marine ecosystem endpoint requires consultation with the Department of Water due to insufficient information about the marine species and level of protection required.

For hazards #1 to #7, chemical and biological data were used from Appendix A2 (Tables A2 to A4). The trigger values for different environmental endpoints may differ according to the hazard (e.g. trigger values for nutrients for public open space irrigation versus freshwater aquatic ecosystems). Table 6 identifies which trigger value is more conservative and thus relevant to assessing the maximal risk for the particular hazard.


Table 6 Data summary to inform maximal risk assessment for Perry Lakes managed aquifer recharge proposal. The entries highlighted in green are those which have sufficient information for risk estimation at this time.

MAR Hazards

Environmental Endpoints and Intended Uses

Aquatic Ecosystems Recreation & Aesthetics

Perry Lakes and Bold Park

Marine/Coastal Habitats

Perry Lakes and Bold Park Reserves

Public open space irrigation

Irrigation from domestic wells

1. Pathogens

Environmental hazards of microbial pathogens have not been identified in the guidelines and are excluded from the risk

assessment at this time.

Not directly relevant to recreation & aesthetic uses of the wetlands

Microbial hazards to human health are not included in this environmental risk report. Risk assessments should be

undertaken with respect to microbial hazards to human health.

2. Inorganic chemicals (see nutrients covered separately under Hazard #4)

Trigger values for copper, tin and zinc are exceeded in the

source water. No data for chlorine,

hydrogen sulphide, beryllium, selenium (Se V) and thallium. Insufficient data for chromium (Cr VI) cyanide, mercury and silver due to

high detection limits

Requires consultation with

the regulators

Fluoride, chloride, sodium, and iron trigger values for irrigation are exceeded in

the source water. Insufficient data for molybdenum due to

detection limits

Information is needed on vegetation being irrigated by

domestic wells

3. Salinity and sodicity

Based on electrical conductivity, source

water exceeds trigger value. See

Table A3.

More information about plant species is needed;

See Appendix A2 (iv) salinity & sodicity

evaluation

4. Nutrients: nitrogen, phosphorous and organic carbon

Nutrients are elevated above

trigger values for freshwater aquatic ecosystems. See

Table A3.

May affect growth of nuisance organisms and visual use of the wetlands. Chlorophyll A data are needed.

The evaluation should be based on the aquatic

ecosystem trigger value because it is more

conservative than the trigger value for irrigation.


MAR Hazards








5. Organic chemicals Preliminary

assessment reveals more data needed.

Preliminary assessment reveals more data needed.

Preliminary assessment reveals more data needed.

6. Turbidity Lake water turbidity data are needed.

The evaluation should be based on the aquatic ecosystem trigger value because it is more conservative than the trigger value for irrigation. Turbidity may affect visual clarity

(i.e. recreation & aesthetic EV) of Perry Lakes and Bold Park.

7. Radionuclides

The evaluation should be based on the irrigation trigger value as these are

relevant.

Not directly relevant to recreation &

aesthetic uses of the wetlands

Not exceeded. See Table A3.

Not exceeded. See Table A3.

8.

Pressure, flow rates, volumes and groundwater levels; if water table rises too high, can cause: o waterlogging o flooding o effects of anoxia on vegetation o mobilisation of pollutants from a nearby contaminated site

Additional studies required: a baseline

study of flora and fauna to determine effects of anoxia;

transient groundwater flow

and transport modelling. See description in Appendix B.

Additional studies required: a baseline study of flora and fauna to determine effects of anoxia; transient

groundwater flow and transport modelling. See description in Appendix B.


domestic wells

9.

Contaminant migration in fractured rock and karstic aquifers; if cracks and/or dissolution features strongly influence groundwater flow directions, they make it difficult to predict transport direction of recharge water. Preferential flow paths may

The hazards of eutrophication,

nutrient imbalance and toxicity to flora and fauna need to be addressed by additional studies required: pumping

tests, recent

The hazards of eutrophication, nutrient imbalance and toxicity to flora and fauna need to be

addressed by additional studies required: pumping tests, recent sampling of ambient groundwater and

lake water quality; geochemical modelling with ambient groundwater and transient groundwater

modelling. See description in Appendix B.


domestic wells


MAR Hazards








exist which can reduce opportunities for natural attenuation of toxicants.

sampling of ambient groundwater and lake water quality;

geochemical modelling with

ambient groundwater and

transient groundwater

modelling. See description in Appendix B.

10.

Aquifer dissolution. If dissolution of minerals or reduction in the aquifer strength occurs, could cause production of turbid water (see Hazard #6); contribute to metal mobilisation problems; preferential flow paths from aquifer dissolution which can reduce opportunities for natural attenuation processes to occur (See Hazard #9).

See Hazard 9 for the list of environmental

hazards and additional studies

needed.

See Hazard 9 for the list of environmental hazards and additional studies needed.


domestic wells

11. Aquifer and groundwater-dependent ecosystems

Additional studies are needed to

survey potential ecosystem receptors (e.g. stygofauna and

Not directly relevant to recreation & aesthetic or irrigation endpoints


MAR Hazards








indigenous microorganisms in the aquifer; fauna

and flora of wetlands and other water

bodies that receive or depend on groundwater; riparian and

terrestrial phreatophytic vegetation)

12. Energy and greenhouse gas considerations

Unknown at present compared to other options to avoid excessive energy use and to minimise greenhouse gas emissions


The data summary reveals that a significant amount of information is lacking. Additional studies are needed as described in Appendix B and consultation with the relevant regulators is needed to clarify the marine ecosystem protection levels.

If we consider the environmental endpoints in Table 6 other than the marine environment, the hazards that can be assessed at this time with available data are salinity, sodicity and nutrients for the Perry Lakes and Bold Park environmental endpoint, and radionuclides for public and domestic irrigation endpoints.

As a demonstration of the risk assessment process, these selected hazards were qualitatively evaluated. The level of risk for each of these hazards was estimated by identifying the likelihood of occurrence and the severity of the consequences if it does happen (NRMMC–EPHC–AHMC, 2006). This approach is different from a quantitative risk estimation, which would require a numerical estimate of risks (e.g. the impact of illness caused by a specific pathogen under a particular exposure scenario).

The descriptive information in Tables 7 and 8 was used to guide decision-making on the qualitative measures of likelihood and consequences or impact. The likelihood and consequences were then combined to provide a qualitative estimation of risk as shown in Table 9.

The following tables are reproduced from the Phase 1 AGWR (NRMMC–EPHC–AHMC, 2006), Tables 2.5 to 2.7:


Table 7 Qualitative measures of likelihood (NRMMC–EPHC–AHMC, 2006).

Descriptor Example description Rare May occur only in exceptional circumstances. May occur once in 100 years Unlikely Could occur within 20 years or in unusual circumstances Possible Might occur or should be expected to occur within a 5- to 10- year period Likely Will probably occur within a 1- to 5- year period Almost certain Is expected to occur with a probability of multiple occurrences within a year

Table 8 Qualitative measures of consequences or impact (NRMMC–EPHC–AHMC, 2006).

Descriptor Example description Insignificant Insignificant impact or not detectable Minor Health – Minor impact for small population

Environment - Potentially harmful to local ecosystem with local impacts contained to site

Moderate Health – Minor impact for large population Environment – Potentially harmful to regional ecosystem with local impacts primarily contained to on-site

Major Health – Major impact for small population Environment – Potentially lethal to local ecosystem; predominantly local, but potential for off-site impacts

Catastrophic Health – Major impact for large population Environmental – Potentially lethal to regional ecosystem or threatened species; widespread on-site and off-site impacts

Table 9 Qualitative risk estimation (NRMMC–EPHC–AHMC, 2006).

Consequences Likelihood Insignificant Minor Moderate Major Catastrophic Rare Low Low Low High High Unlikely Low Low Moderate High Very high Possible Low Moderate High Very high Very high Likely Low Moderate High Very high Very high Almost certain Low Moderate High Very high Very high

Note: Level of environmental risk is specific to definitions of likelihood and consequences defined in the tables above.

Table 10 applies this process to the hazards that could be assessed at this time for the Perry Lakes proposal. Note that human health hazards were not considered here, as they were not part of this study.


Table 10 Maximal risk assessment for several hazards only for the Perry Lakes managed aquifer recharge proposal.

MAR Hazard Environmental Endpoint or Intended Uses

Likelihood Impact/consequence Risk

Salinity and sodicity

Perry Lakes and Bold Park aquatic ecosystems

Almost certain based on electrical conductivity exceeding the trigger value

Minor as it may be potentially harmful to the local ecosystem with local impacts contained to the site

Moderate

Nutrients Perry Lakes and Bold Park aquatic ecosystems

Almost certain based on nitrogen, phosphorus and organic carbon concentrations exceeding their respective trigger values

Minor as it may be potentially harmful to the local ecosystem with local impacts contained to the site

Moderate

Radionuclides Public open space and domestic irrigation

Rare based on gross alpha and beta data

Insignificant Low

10. STEP 9 – FURTHER REQUIREMENTS TO ADDRESS THE GUIDELINES

The data summary reveals that a significant amount of information is lacking. Additional studies are needed as described in Appendix B and consultation with the relevant regulators is needed to clarify the marine ecosystem protection levels.

The cursory water quality assessment conducted in Appendix A2 demonstrates the level of knowledge at this stage of project development. The results reveal that greater sampling of source water concentrations of organic compounds is needed with a targeted approach to protecting key species. An eco-toxicity assessment is recommended. The selection of organic compounds to include in the monitoring program requires careful consideration in light of the fact that there are 85 organic compounds listed in Appendix Table A4 and potentially other organic compounds such as pharmaceutical and disinfection by-products.

A survey to identify necessary aquatic species to protect at Perry Lakes is needed to ensure that the range of organic compounds being sampled for is directly relevant. It should be noted that as part of the PCRP study, a large number of pharmaceuticals and disinfection by-products were sampled, but the relevance of these classes of organic compounds to aquatic species would require an in-depth eco-toxicity assessment.

There are additional stages of project development and assessment that were not covered in this report, which are further requirements to address the guidelines. As outlined in Figure 1.3 of the AGWR for MAR, the steps following the maximal risk assessment as part of Stage 2 are to (i) identify preventative measures needed for validation, such as operational procedures, critical control points, contingency plans; and (ii) conduct a residual risk assessment of the validation stage which will forecast residual risk of validation (NRMMC-EPHC-NHMRC, 2009). In Stage 3 the project is constructed and trials are performed. Commissioning is required to validate preventative measures and a list of methods of validation monitoring is provided in Appendix 3 of the AGWR. At this stage, an assessment is required to evaluate the residual risk and uncertainty with the preventative measures in place. Stage 4 is project operation and verification. As described in Chapters 5-7 of the


AGWR, a risk management plan and operational monitoring are required for the AGWR for MAR.


APPENDIX A. COMPLETED INVESTIGATIONS TO INFORM RISK ASSESSMENT This section of the report provides a description of the investigations that were identified as required in the Stage 1 assessment of the degree of difficulty of the proposed MAR project. Initial steady-state groundwater flow modelling and an initial water quality assessment are presented in this section as support for the maximal risk assessment.

Appendix A1. Groundwater modelling A steady-state, two-dimensional groundwater flow model of the aquifer around Perry Lakes was constructed using Visual AEM 1 (version 1.04). The purpose of the modelling was to assess the impact of a 1.3 km long infiltration gallery located along Perry Lakes Drive (as shown in Figures 1, 2 and 3). The model predicted the amount of water table rise in response to infiltration via the gallery. The resultant increase in lake level for East and West Lakes was calculated based on the predicted increases in water table elevation at the locations of the lakes. The predicted extent and depth of surface water in the lakes was determined from detailed lakebed bathymetry prepared by Rich (2004).

A single model layer was used to represent the saturated section of the unconfined superficial aquifer. Figure A1 depicts the model domain, which was separated into two zones: (1) a coastal zone with aquifer transmissivity 2,200 m2/d based on pumping test data analysed by Rich (2004); and (2) a less conductive inland zone with transmissivity 700 m2/d. The model did not simulate flow processes in the unsaturated zone. Instead, recharge was applied directly to the water table. Infiltration from the gallery was simulated using a horizontal well with the injection rate set equal to I x L x W, where I is the assumed infiltration rate (m/d), L is the gallery length (1,300 m), and W is the gallery width (1 m). Constant head boundary conditions representing mean sea level were assigned along the ocean and estuary shore lines. A simple calibration was carried out manually by adjusting the groundwater recharge rate, and visual matching of the simulated water table contours with those produced by Rich (2004) for May 1997 (Figure A2). The hydrographs and location map in Figure A3 indicate seasonal water table changes of less than a meter within a few hundred meters of the lakes between 1996 and 1997. The calibration result depicted in Figure A1 was achieved using a uniformly distributed recharge rate of 0.128 m/yr over the entire domain, which is equivalent to 16 percent of average annual rainfall of 0.8 m/yr. The model did not simulate groundwater extraction from wells and therefore the simulated recharge rate represents an estimate of the net excess of average groundwater recharge over average groundwater extraction and evapotranspiration losses within the modelled area.

Scenarios were modelled to predict the relationship between infiltration volumes and water table response. Each scenario involved a different rate of gallery infiltration at 1, 2, 3, 4 or 5 m/day (Table A1). Infiltration at 1 m/day was equivalent to 1.3 ML/day for the dimensions of the gallery. Modelling revealed that simulating larger infiltration volumes produced higher groundwater levels. The application of higher recharge rates revealed the potential for some treated wastewater to flow toward Perry Lakes; however, a limitation of the steady-state model was that it could not be used to predict how far the wastewater plume would extend toward the lakes or if and how long it would take wastewater to reach the lakes. The risk assessment shows that such modelling is required to assess how to operate the infiltration gallery to achieve its objectives.

Table A1 and Figure A4 indicate the results from five infiltration scenarios. A water table rise of approximately 1 m compared to current levels was predicted from applying an infiltration volume of 5.3 ML/d and was recommended for enhancing the lakes. At a higher infiltration volume of 6.7 ML/day groundwater levels were impacted farther from the reserve and further testing and model calibration is required to confirm this extent of impact on the aquifer. The modelling indicated that greater water table rise would occur to the east of the gallery due to

1http://www.civil.uwaterloo.ca/jrcraig/VisualAEM/Main.html


‘back up’ of regional groundwater flow on the up-gradient side of the gallery. Under equilibrium (steady state) conditions the treated wastewater from the gallery would flow in a westerly direction toward the coast. The increase in aquifer storage to the east of the gallery would occur due to build up of local recharge and regional groundwater flow behind the partial hydraulic barrier formed by water table rise beneath the gallery.

Predicted water level rise in West Lake was greater than in East Lake due to its proximity to the infiltration gallery. It was estimated from the modelling results that East Lake would be less than half full and West Lake would be greater than half full if an infiltration volume of 5.3 ML/d could be achieved. It was estimated that to completely fill West Lake would require an infiltration volume of at least 6 to 7 ML/day.

Table A1 Simulated rise in groundwater level from different rates of infiltration

Infiltration (m/day) Total Infiltration (ML/day)

Increase in the Water Table in the Vicinity of the Gallery (m)

1 1.3 0.2-0.3

2 2.7 0.4-0.6

3 4.0 0.6-0.9

4 5.3 0.8-1.1

5 6.7 1.1-1.5


Figure A1 Model domain and calibrated water table contours in metres above mean sea level.


Figure A2 Contours of minimum water table elevation for May 1997 from Rich (2004).


1.50

2.00

2.50

3.00

3.50

4.00

Wat

er L

evel

(m

AH

D)

Date

WL18WL21WL5WL1WL25 - Camel Lake bore

Legend

Proposed location of infiltration galleries

Location of bores with hydrographs shown in the accompanying figure. Water level change between early October 1996 (maximum) and late March 1997 (minimum) is noted in parentheses.

N

Bold Park

WestLake

WL25 (0.55 m)

WL21 (0.67 m)

East Lake

WL1 (0.93 m)

WL18 (0.88 m)

WL5 (0.61 m)

Figure A3 Close-up location map of Perry Lakes showing a subset of the many bores with water level data (Rich, 2004). Hydrographs were prepared using water level data measured manually by John Rich (personal communication).


Figure A4 Results from steady-state simulations of groundwater level rise in response to different rates of infiltration applied to a 1.3 km-long by 1 m- wide gallery along Perry Lakes Drive. The contours indicate water table rise compared to the calibrated levels in Figure A1.


Appendix A2. Source water quality assessment This section of the report involves a source water quality assessment in view of protecting the environmental values of the aquifer and intended uses of recovered water as identified in Step 5: (1) aquatic ecosystem protection, (2) irrigation, and (3) recreation and aesthetics. It describes the process, highlights gaps in knowledge related to conducting the water quality assessment and provides a starting point for designing a monitoring program.

With regard to aquatic ecosystems, the focus is on freshwater species. While it is acknowledged that water quality protection of marine ecosystem in coastal habitats is relevant to the proposed MAR at Perry Lakes as discussed in Section 6.4, further consideration in consultation with the relevant regulators is required to identify marine species and the level of protection required. The procedure for conducting the source water and receiving water body quality assessment described below should be followed, using trigger values relevant to marine waters, which are available in ANZECC-ARMCANZ (2000) for different levels of species protection (see Table 3.4.1; Tables 3.3.5 to 3.3.7), and in the WA EPA guidelines (see Tables 2.2; 2.5-2.6 in EPA1993).

i. Assessing water quality parameters A comprehensive list of physical characteristics, biological parameters and inorganic toxicants was assembled from the guidelines. A list of organic toxicants was also assembled from the guidelines, but these relate only to the protection of aquatic ecosystems and not irrigation. Trigger values were available for a range of aromatic hydrocarbons, phenols, phthalates, pesticides and herbicides. The assessment of organic toxicants is incomplete as there was limited sampling of source water for these compounds.

Trigger values for ecosystem protection were collected from several sources, including several that are specific to Western Australia and south-west WA, in particular. Default trigger values for physical and some chemical stressors for south-west Australia for slightly disturbed ecosystems (wetlands) are from Table 3.3.6 in ANZECC-ARMCANZ (2000). Trigger values for electrical conductivity and turbidity indicative of slightly disturbed ecosystems in south-west Australia (category lakes, reservoirs & wetlands) are from Table 3.3 in ANZECC-ARMCANZ (2000), and trigger values for toxicants applying to typical slightly to moderately disturbed conditions are from Table 3.4.1 in ANZECC-ARMCANZ (2000). The default trigger value for defining unnatural change in water temperature is from Table 3.3.1 in ANZECC-ARMCANZ (2000). For some water quality parameters, guidelines from the WA Environmental Protection Authority (1993) for the protection of aquatic ecosystems (fresh waters) were used because there were no trigger values given in the ANZECC-ARMCANZ (2000) guidelines.

In assessing source water quality, freshwater ecosystem protection and irrigation were both considered to identify the more conservative of the associated guidelines for each parameter. Thus, for each water quality parameter listed in Table A2 where trigger values for both EVs exist, the lesser of either the ecosystem trigger value or the long-term trigger value for irrigation (LTV) was selected for comparison with source water quality values in Table A3. PCRP data are from Lugg & Western Australia Dept. of Health (2009) and Rodriguez et al. (2009). FIG study data are source water with additional treatment via passage through an Amiad-designed multi-media filter system from Bekele et al. (2009). For some water quality parameters, trigger values are irrelevant for ecosystem protection (e.g. fluoride) and the source water quality comparison was conducted on the basis of LTVs for irrigation. LTVs for irrigation are from the ANZECC-ARMCANZ (2000) chapter on primary industries. However, for the majority of the water quality parameters in Table A2, the trigger value either existed only for ecosystem protection or the ecosystem trigger value was lower than the LTV and hence used for assessing the source water quality in Table A3.


Table A2 Comparison of trigger values for ecosystem protection and irrigation, including physical characteristics, inorganic toxicants and radiological characteristics. N.R.E. indicates that the parameter is ‘not relevant for ecosystem’ protection for freshwater species; N.R.I. indicates that it is ‘not relevant for irrigation’ as there is no LTV identified for the parameter.

Trigger value for freshwater

ecosystem protection

Reference for

ecosystem trigger value *

LTV for irrigation; (√√√√) marked if LTV was

used instead of the ecosystem trigger value

for the assessment

Physical characteristics

Water temperature >80 %ile <20 %ile r1 N.R.I.

pH, lower limit 7 r2 6 √√√√

pH, upper limit 8.5 r2 8.5 Electrical conductivity (mS/m) 30-150 r3 65

Turbidity (NTU) 10-100 r3 N.R.I. Suspended particulate matter

10% change in seasonal mean concentration r5 N.R.I.

Colour & clarity 10% change in euphotic depth† r5 N.R.I.

Dissolved oxygen >6 mg/L (>80-90% saturation)‡ r5 N.R.I.

Biological parameters

Human and animal pathogens

Premature to recommend specific values for these indicators. Biological

evaluation is recommended. r5

1,000 faecal coliforms per 100

mL§ √√√√

Nutrients (mg/L)

Chlorophyll A 0.03 r2 N.R.I.

NOx as N 0.1 r2 N.R.I.

Ammonium 0.04 r2 N.R.I.

Ammonia as N 0.9 r2 N.R.I.

Total nitrogen 1.5 r2 5.0 Filterable reactive phosphorus 0.03 r2 N.R.I.

Total phosphorus** 0.06 r2 0.05 √√√√ Non-metallic inorganics (mg/L)

Chlorine 0.003 r4 N.R.I.

Cyanide 0.007 r4 N.R.I.

Hydrogen sulfide 0.001 r4 N.R.I.

Fluoride N.R.E. --- 1.0 √√√√

Chloride N.R.E. --- 175 √√√√

Sodium N.R.E. --- 115 √√√√

Metals and metalloids

* References for ecosystem trigger values are: Table 3.3.1 (r1), Table 3.3.6 (r2), Table 3.3.7 (r3), and Table 3.4.1 (r4) in ANZECC-ARMCANZ (2000), and Table 2.2 (r5) in the WA EPA guidelines in EPA (1993). † For systems where depth is greater than half of the euphotic depth. For waters shallower than half of the euphotic depth, the maximum reduction in light at the sediment bed should not exceed 20% (EPA 1993). ‡ Dissolved oxygen measured over at least one, preferably several, diurnal cycles (EPA 1993). § Tentative value. Geometric (log) mean of not less than 5 water samples taken per month; no more than 20% should exceed 4,000 organisms per 100 mL (EPA, 1993). ** The LTV for phosphorus has been set to minimise the risk of algal blooms developing in storage facilities, and to reduce the likelihood of bio-fouling in irrigation equipment (ANZECC-ARMCANZ, 2000).


Trigger value for freshwater

ecosystem protection

Reference for

ecosystem trigger value *

LTV for irrigation; (√√√√) marked if LTV was

used instead of the ecosystem trigger value

for the assessment (mg/L)

Aluminium - Total (pH>6.5) 0.055 r4 5

Aluminium - Total (pH<6.5) <0.05 r5 5

Antimony - Total 0.03 r5 0.1

Arsenic (As III) 0.024 r4 0.1

Arsenic (As V) 0.013 r4 0.1

Beryllium 0.004 r5 0.1

Boron - Soluble 0.37 r4 0.5

Cadmium - Total 0.0002 r4 0.01

Chromium 0.01 r5 0.1

Chromium (Cr VI) 0.001 r4 0.1

Cobalt - Total N.R.E. --- 0.05 √√√√

Copper 0.0014 r4 0.2

Iron†† 1.0 r5 0.2 √√√√

Lead 0.001 – 0.005 r5 2.0

Lithium N.R.E. --- 2.5 √√√√

Manganese - Total 1.9 r4 0.2 √√√√

Mercury (inorganic) 0.00006 r4 0.002

Mercury (methyl) 0.0001 r4 0.002

Molybdenum - Total N.R.E. --- 0.01 √√√√

Nickel - Total 0.011 r4 0.2

Selenium (Total) 0.005 r4 0.02

Selenium (Sel V) 0.005 r5 0.02

Silver - Total 0.00005 r4 N.R.I.

Thallium 0.004 r5 N.R.I.

Tin (tributyltin) 8.0E-06 r5 N.R.I.

Uranium - Total N.R.E. --- 0.01 √√√√

Vanadium - Total N.R.E. --- 0.1 √√√√

Zinc - Total 0.005 – 0.05 r5 2.0

Radionuclides (Bq/L)

Gross alpha‡‡ N.R.E. --- 0.5 √√√√

Gross beta§§ N.R.E. --- 0.5 √√√√

†† With regard to the ecosystem trigger value for iron from EPA (1993), this is provided iron is not present as Fe (II). ‡‡ Gross alpha and beta recommendations are given to simplify the screening measurements and monitoring. Specific radionuclide analysis would be appropriate if these values were exceeded (ANZECC-ARMCANZ, 2000). §§ Gross beta trigger value does not include the contribution due to potassium-40.


Table A3 Comparison of trigger values and Subiaco WWTP source water quality. Identifiers are used to indicate whether the trigger value is for ecosystem protection (E) or irrigation (LTV) as the lesser of these was used for the assessment. Source water values in bold text are equal to or exceed the trigger value. I.D. indicates ‘insufficient data’ either because the parameter was not measured or not available despite data requests. Data from the PCRP were reported as mean values as no raw data were available to determine the 95th percentile values. Red shading in the left margin adjacent to parameter column indicates additional data is needed or the trigger value was exceeded.

Trigger value

Source water quality data

PCRP study

(mean)

# of PCRP

samples

FIG study (95th

percentile)

# of FIG

samples


Water temperature

>80 %ile <20 %ile E

*Requires lake water data to complete the assessment

pH, lower limit 6 LTV

See assessment based on upper pH limit and 95%ile value for source water; minimum pH = 6.8 from FIG study (count =19 samples)

pH, upper limit 8.5

LTV and E I.D. -- 8.5 40

Electrical conductivity (mS/m) 30-150 E I.D. -- 225 53 Turbidity (NTU) 10-100 E I.D. -- 6.5*** 19

Suspended particulate matter

10% change in seasonal mean concentration E

*Requires lake water data to complete the assessment.

Colour & clarity

10% change in euphotic depth E

*Requires lake water data to complete the assessment

Dissolved oxygen 6 mg/L E I.D. -- 5.7 49 Biological parameters

Human and animal pathogens

1,000 faecal coliforms per 100

mL LTV I.D. -- TNC 46 Nutrients (mg/L) Chlorophyll A 0.03 E I.D. -- I.D. -- NOx as N 0.1 E I.D. -- I.D. -- Ammonium 0.04 E I.D. -- I.D. -- Nitrate as N Not defined† -- 6.23 220 4.77 42 Nitrite as N Not defined† -- 0.33 219 I.D. -- Total Kjeldahl nitrogen Not defined† -- 5.1 250 3.03 20 Organic nitrogen Not defined† -- 3.3 44 I.D. -- Ammonia as N 0.9 E 1.9 250 1.9 20 Total nitrogen 1.5 E I.D. -- 8.9 22 Filterable reactive phosphorus 0.03 E I.D. -- 12.0 42 Total phosphorus 0.05 LTV 8.7 250 I.D. -- Non-metallic inorganics (mg/L) Chlorine 0.003 E I.D. -- I.D. --

*** Caution is warranted in considering the source water turbidity data from the FIG study which involved additional treatment by rapid sand filtration. Electrical conductivity may also be affected, but the FIG data reveals the EC trigger value was exceeded despite filtration. † Although there is no trigger value given explicitly for these individual nitrogen species, the source water values can be compared with the trigger value for NOx as N or total nitrogen.


Trigger value

Source water quality data

PCRP study

(mean)

# of PCRP

samples

FIG study (95th

percentile)

# of FIG

samples

Cyanide 0.007 E <0.01 4 I.D. -- Hydrogen sulfide 0.001 E I.D. -- I.D. -- Fluoride 1.0 LTV 0.95 1 1.0 15 Chloride 175 LTV 206 1 304 63 Sodium 115 LTV 170 1 249 42 Metals and metalloids (mg/L) Aluminium - Total (pH>6.5) 0.055 E 0.03 4 0.04 42

Aluminium - Total (pH<6.5) <0.05 E See assessment based on pH >6.5 since

minimum pH = 6.8 from FIG study Antimony - Total 0.03 E 0.0002 4 0.0003 10

Arsenic (As III) 0.024 E I.D. -- 0.001 (total

Arsenic) 20

Arsenic (As V) 0.013 E I.D. -- 0.001 (total

Arsenic) 20 Beryllium 0.004 E I.D. -- I.D. -- Boron - Soluble 0.37 E 0.29 4 0.35 60 Cadmium - Total 0.0002 E I.D. -- <0.0001 25

Chromium 0.01 E I.D. -- <0.002

(total Cr) 14

Chromium (Cr VI) 0.001 E I.D. -- <0.002

(total Cr) 14 Cobalt - Total 0.05 LTV 0.004 4 <0.005 18 Copper 0.0014 E 0.007 4 0.01 20 Iron 0.2 LTV 0.1 4 0.64 42 Lead 0.001 E 0.0003 4 0.0008 25 Lithium 2.5 LTV 0.007 4 I.D. -- Manganese - Total 0.2 E 0.02 4 0.06 25

Mercury (inorganic) 0.00006 E I.D. -- <0.0005

(total Hg) 24

Mercury (methyl) 0.0001 E I.D. -- <0.0005

(total Hg) 24 Molybdenum - Total 0.01 LTV 0.004 4 <0.02 14 Nickel - Total 0.011 E 0.002 4 0.002 25 Selenium (Total) 0.005 E I.D. -- <0.001 14 Selenium (Sel V) 0.005 E I.D. -- I.D. -- Silver - Total 0.00005 E I.D. -- <0.005 14 Thallium 0.004 E I.D. -- I.D. -- Tin (tributyltin) 8.0E-06 E 0.0003 4 I.D. -- Uranium - Total 0.01 LTV I.D. -- <0.0001 14 Vanadium - Total 0.1 LTV I.D. -- <0.005 14 Zinc - Total 0.005 E 0.053 4 0.08 25 Radionuclides (Bq/L) Gross alpha 0.5 LTV 0.025 2 I.D. -- Gross beta 0.5 LTV 0.026 1 I.D. --

Water quality parameters for recreation and aesthetics are specified in the ANZECC-ARMCANZ (2000) and WA EPA guidelines as outlined in Step 5 (Recreation & Aesthetic EVs section of this report). With regard to the level of use, which is visual use and not


primary or secondary contact, the parameters to consider are visual clarity and colour (Table A3) with additional specifications on the change in natural hue of the water and the natural reflectance, surface films from oil and debris, and nuisance organisms (EPA, 1993).

ii. Assessing organic toxicants The water quality assessment should consider organic compounds; however, there are limited data for this case study and therefore this section of the report cannot be completed at this stage. Trigger values for freshwater ecosystem protection are available from ANZECC-ARMCANZ (2000) and the WA EPA (1993) for 85 organic compounds, which include aromatic hydrocarbons, phenols, phthalates, pesticides or herbicides (Table A4). Trigger values from ANZECC-ARMCANZ (2000) and the WA EPA were compared to determine any differences and to preferentially use data from WA if it existed. Trigger values for organic toxicants are available from the WA EPA for approximately half of those listed in Table A4. Approximately a quarter of the organic toxicants listed have trigger values from both ANZECC-ARMCANZ (2000) and the WA EPA; trigger values from the latter were generally lower. The next step after organising the trigger value data was to compare with source water quality data which was available from the PCRP study in Rodriguez et al. (2009). Concentrations of o-xylene and 1,2-dichlorobenzene were the only organic compounds that were determined in the source water and have trigger values for comparison. Measured concentrations of both compounds were below the corresponding trigger values. Table A4 Trigger values for organic toxicants for freshwater ecosystem protection and comparison with source water data. Concentrations in µg/L. N.D. means ‘no data’ for trigger value given from the reference indicated. From this list, only two of these compounds were analysed for in the source water as noted in the rightmost column.

Trigger value for freshwater ecosystem protection for

slightly to moderately disturbed systems

(ANZECC-ARMCANZ, 2000)

Guidelines for protection of fresh water aquatic ecosystems from WA

EPA (EPA 1993)

Mean measured concentration and

(n =# of water samples) from the PCRP study

ORGANIC ALCOHOLS

Ethanol 1400 N.D.

CHLORINATED ALKANES

Hexachloroethane 290 N.D.

ANILINES

Aniline 8 N.D.

2,4-dichloroaniline 7 N.D.

3,4-dichloroaniline 3 N.D.

AROMATIC HYDROCARBONS

Benzene 950 300

o-xylene 350 N.D. 0.06 (n =4)

p-xylene 200 N.D.

Toluene N.D. 300

Polycyclic Aromatic Hydrocarbons Polycyclic aromatic hydrocarbons - total N.D. 3

Naphthalene 16 N.D.

Nitrobenzenes

Nitrobenzene 550 N.D.

Nitrotoluenes

2,4-dinitrotoluene 16 N.D.

2,4,6-trinitrotoluene 140 N.D.






EPA (EPA 1993)



Chlorobenzenes and Chloronaphthalenes

Monochlorobenzene N.D. 15

1,2-dichlorobenzene 160 2.5 1.83 (n =4)

1,3-dichlorobenzene 260 2.5

1,4-dichlorobenzene 60 4

1,2,3-trichlorobenzene 3 0.9

1,2,4-trichlorobenzene 85 0.5

1,3,5-trichlorobenzene N.D. 0.7 1,2,3,4-tetrachlorobenzene N.D. 0.1 1,2,3,5-tetrachlorobenzene N.D. 0.1 1,2,4,5-tetrachlorobenzene N.D. 0.2

Pentachlorobenzene N.D. 0.03

Hexachlorobenzene N.D. 0.007

Polychlorinated Biphenyls (PCBs) & Dioxins

Aroclor 1242 0.3 N.D.

Aroclor 1254 0.01 N.D. Polychlorinated biphenyls N.D. 0.001

PHENOLS and XYLENOLS

Phenol 320 50

2-chlorophenol 340 N.D.

4-chlorophenol 220 N.D.

2,4-dichlorophenol 120 0.2

2,4,6-trichlorophenol 3 N.D. 2,3,4,6- tetrachlorophenol 10 N.D.

Monochlorophenol N.D. 7

Tetrachlorophenol N.D. 1

Pentachlorophenol 3.6 0.05

Trichlorophenol (total) N.D. 18

Nitrophenols

2,4-dinitrophenol 45 N.D.

PHTHALATES

Dimethylphthalate 3700 N.D.

Diethylphthalate 1000 N.D.

Dibutylphthalate 9.9 4

Di(2-ethylhexyl)phthalate N.D. 0.6

other phthalate esters N.D. 0.2

MISCELLANEOUS INDUSTRIAL CHEMICALS Poly(acrylonitrile-co-butadiene-costyrene) 530 N.D.

Hexachlorobutadiene N.D. 0.1

ORGANOCHLORINE PESTICIDES

Aldrin N.D. 0.002

Chlordane 0.03 0.004

DDE N.D. 0.014






EPA (EPA 1993)



DDT 0.0006 0.0005

Dieldrin N.D. 0.002

Endosulfan 0.03 0.0007

Endrin 0.01 0.003

Heptachlor 0.01 0.0003

Lindane 0.2 0.003

Methoxychlor N.D. 0.04

Mirex N.D. 0.001

Toxaphene 0.1 0.008

ORGANOPHOSPHORUS PESTICIDES

Azinphos methyl 0.01 0.01

Chlorpyrifos 0.01 0.001

Demeton N.D. 0.1

Diazinon 0.01 N.D.

Dimethoate 0.15 N.D.

Fenitrothion 0.2 N.D.

Malathion 0.05 0.07

Parathion 0.004 0.004

CARBAMATE & OTHER PESTICIDES

Carbofuran 0.06 N.D.

Methomyl 3.5 N.D.

PYRETHROIDS

Esfenvalerate 0.001 N.D.

HERBICIDES & FUNGICIDES

Diquat 1.4 N.D.

Phenoxyacetic acid herbicides

2,4-D 280 N.D.

2,4,5-T 36 N.D.

Thiocarbamate herbicides

Molinate 3.4 N.D.

Thiobencarb 2.8 N.D.

Thiram 0.01 N.D.

Triazine herbicides

Atrazine 13 N.D.

Simazine 3.2 N.D.

Urea herbicides

Tebuthiuron 2.2 N.D.

Miscellaneous herbicides

Acrolein N.D. 0.2

Glyphosate 370 N.D.

Trifluralin 2.6 N.D.

SURFACTANTS Linear alkylbenzene sulfonates (LAS) 280 N.D. Alcohol ethoxyolated sulfate (AES) 650 N.D. Alcohol ethoxylated surfactants (AE) 140 N.D.


iii. Comparison of ambient groundwater, lake water and source water qualities

Ambient groundwater data from Perry Lakes Reserve are from sampling 13 piezometers, including 4 piezometer nests on a single occasion on 14-May 2007 (Tony Smith, personal communication). The wells that were sampled include four piezometer nests (N1a,b,c; N2a,b,c; N3a,b,c; N4a,b,c) and WL6 (Figure A5). The same unconfined aquifer was sampled for ambient groundwater as part of the FIG study and these data are included in Table A5 as more samples were collected to determine a wider range of constituents in groundwater than the samples collected from the piezometers at Perry Lakes Reserve. Ambient groundwater data in Table A5 are from both Tony Smith (personal communication) and Bekele et al. (2009); where there were ambient groundwater parameter data available from both sources, preference was given to the water quality data from Tony Smith as these were collected from near the lakes.

Lake water quality data for East and West Perry Lakes are from several data sets as shown in Table A5. Dames and Moore (1992) reported on the water quality of the lakes from water samples collected on 6-August 1991 that were to determine for pH, TDS, total phosphorous, orthophosphate, ammonia, total Kjeldahl nitrogen, lead, zinc and hydrocarbons (oil and grease). PPK (2000) in their Environmental Management Plan for Perry Lakes referred to the earlier study by Dames and Moore (1992) and did not undertake additional sampling for the Town of Cambridge. Rich (2004) provides lake chloride chemistry data that were collected to analyse lake-aquifer interactions and the effects of artificial maintenance of lake levels. The most recent sampling was conducted on 1-March 2007 by the Water Corporation to aid development of the MAR proposal. The water samples were collected to analyse nutrient levels in Perry Lakes and the groundwater used to fill the lakes. On this sampling occasion, groundwater from Bore #44 used to fill East Lake, groundwater from Bore #43 used to fill West Lake and lake water from East Lake were collected. These samples were analysed for nitrate, total Kjeldahl nitrogen, ammonia and total dissolved solids (Table A5).


N

Figure A5 Map of Perry Lakes monitoring wells and irrigation bores modified after Rich (2004) to show the location of thirteen wells that were sampled for ambient groundwater quality (highlighted in red on the map). Wells labelled a,b,c are separate piezometers. Sampling occurred on 14-May 2007 (Tony Smith, personal communication).


Table A5 Comparison of selected parameters in ambient groundwater, Perry Lakes lake water and Subiaco WWTP source water. N.D. indicates ‘no data’ for that particular parameter.

Source water from

the Subiaco WWTP mean values

Reference for source

water quality *

Ambient groundwater; mean values (n=# of water

samples)

Reference for ambient

groundwater quality †

Perry Lakes -East and West Lake water quality (as indicated) n= # of water samples

per lake


Water temperature 24.0 (n=53) S2 21.9 (n=52) R2 N.D.

pH 7.3 (n=40) S2 7.3 (n=13) R1

Recorded pH values from 5.5 to 10.5.

During field survey (1991), West Lake had a higher pH than East Lake and the range

was 7.81 to 8.82 (n=2) from Dames and

Moore (1992) Electrical conductivity (mS/m) 147† (n=53) S2 157 (n=13) R1 N.D.

Total dissolved solids (mg/L) 813 (n=203) S2 644 (n=11) R2

106-108 mg/L in West Lake (n=2); 168-192 mg/L (n=2) in East Lake (Dames and

Moore, 1992)‡; 770 to 873 mg/L (n=3) from

Water Corp. sampling in 2007

Turbidity (NTU) 2.77† (n=19) S2 109 (n=9) R2 N.D.

Suspended solids 19 (n=1626) S1 2.0 (n=3) R2 N.D. Dissolved oxygen (mg/L) 2.15 (n=49) S2 4.0 (n=45) R2 N.D.

Nutrients (mg/L)

Nitrate as N 6.23 (n=220) S1 0.10 (n=13) R1

<1.0 mg/L (n=3) from Water Corp. sampling

in 2007

Total Kjeldahl nitrogen 5.1 (n=250) S1 0.07 (n=11) R2

<5 mg/L detection limit (n=2) from Dames and Moore (1992); 1.4 to 4.5 mg/L (n=3) from


* References for source water quality are from the PCRP study (S1) as reported in Lugg & Western Australia Dept. of Health (2009) and Rodriguez et al. (2009); source water data from the FIG study (S2) are from Bekele et al. (2009). Where both studies provided source water quality data for a particular parameter, preference was given to showing the PCRP data, except where there were too few water samples (i.e. ≤ 4 samples) in which case FIG data are shown as they provided a larger dataset and revealed higher means than the PCRP data. (†)Caution is recommended in interpreting the FIG source water data for turbidity and EC as these parameters were likely affected by filtration. † References for ambient groundwater are from 13 piezometers sampled by Tony Smith (personal communication) labelled as R1 and the same aquifer monitored for the FIG study from Bekele et al. (2009), labelled as R2. ‡ According to Dames and Moore (1992), the difference in TDS between the lakes reflects the greater contribution of stormwater runoff during winter, typically with lower concentrations of dissolved solids to West Lake.


Source water from

the Subiaco WWTP mean values

Reference for source

water quality *

Ambient groundwater; mean values (n=# of water

samples)

Reference for ambient

groundwater quality †

Perry Lakes -East and West Lake water quality (as indicated) n= # of water samples

per lake

Ammonia as N 1.9 (b=250) S1 <0.01 (n=11) R2

<5 mg/L detection limit (n=2) from Dames and Moore (1992); 0.73 to 5.4 mg/L (n=3) from


Total nitrogen 4.28 (n=22) S2 4.1 (n=13) R1

<5 mg/L detection limit (n=2) from Dames and

Moore (1992)

Total phosphorus 8.7 (n=250) S1 N.D. --

Ranged from 0.01 to 0.03 mg/L (n=2) with

the highest value being obtained from East Lake (Dames and

Moore, 1992)§ Soluble reactive phosphorus 6.3 (n=42) S2 0.01 (n=24) R2 N.D.

Total organic carbon 10.0 (n=41) S1 2.5 (n=35) R2 N.D.

Non-metallic inorganics (mg/L)

Sulphate 76 (n=42) S2 68 (n=13) R1 N.D.

Chloride 304 (n=63) S2 277 (n=13) R1 N.D.

Sodium 194 (n=42) S2 176 (n=13) R1 N.D.

Metals and metalloids (mg/L)

Iron 0.64 (n=42) S2 1.57 (n=13) R1 N.D.

Lead 0.0008 (n=25) S2 0.0002 (n=17) R2

<0.1 mg/L detection limit (n=2) from Dames

and Moore (1992)

Zinc - Total 0.08 (n=25) S2 0.009 (n=17) R2

<0.01 mg/L detection limit (n=2) from Dames

and Moore (1992)

Other toxicants

Oil & Grease 0.025 (n=2) S1 N.D. --

3 to 4 mg/L (n=4) from Dames and Moore

(1992)

The comparison of water qualities in Table A5 reveals that ambient groundwater and source water have comparable mean values for water temperature, pH, and total nitrogen. Caution is warranted in considering the source water electrical conductivity and turbidity data as these were from the FIG study which involved additional treatment by rapid sand filtration. Although the mean turbidity of source water was less than that of ambient groundwater, the additional treatment is likely to have influenced this result. The source water had higher mean concentrations of total dissolved solids, suspended solids, nitrate, TKN, ammonia, phosphorus, total organic carbon, sulphate, chloride, sodium, lead and zinc than mean concentrations of these parameters measured in ambient groundwater. The mean TDS for the source water, however, was comparable to lake water TDS measurements collected in 2007 by the Water Corporation. The mean concentration of phosphorus was highest in the

§ According to Dames and Moore (1992), the measured phosphorus concentrations in Perry Lakes indicated the lakes were in a mesotropic state when sampled in August 1991, but historical measurements of orthophosphate reveal evidence of hyper-eutrophic conditions with concentrations > 0.1 mg/L.


source water compared to ambient groundwater and lake water. Mean concentrations of dissolved oxygen as well as iron were higher in ambient groundwater relative to the source water, but there are no lake water data for these analtyes for comparison. Measured concentrations of oil & grease were higher in lake water compared with that of the source water.

Lake water quality data for Perry Lakes is very limited as shown by the few samples tabulated above. The lake water data in Table A5 highlights the lack of data for several parameters (i.e. water temperature, electrical conductivity, turbidity, suspended solids, dissolved oxygen, total organic carbon, sulphate, chloride, sodium and iron) and the limited numbers of samples that have been collected for the other parameters to date.


iv. Salinity and sodicity evaluation Salinity refers to the presence of soluble salts in soil or water and is measured from total dissolved solids or sodium content. Sodicity refers to the abundance of sodium relative to calcium and magnesium that can lead to poor soil structure.

For the maximal risk assessment of irrigation water, the irrigation water is considered to be undiluted source water that has been pumped from the aquifer at the MAR site or further down-gradient. The likelihood of increased salinity affecting plant growth is almost certain given that the sodium trigger value for irrigation was exceeded in the source water (Table A3). The risks are minor because the grasses used for irrigation of public open spaces are salt tolerant; however there is insufficient data regarding other plants being irrigated in the Reserves. Overall the level of risk is moderate for salinity, but additional work is needed to identify the plant species and salt tolerance levels in Perry Lakes Reserve and near Camel Lake.

To evaluate whether irrigation would lead to a soil sodicity problem, the electrical conductivity and sodium adsorption ratio (SAR) of the source water were superimposed on Figure A6 from ANZECC-ARMCANZ (2000) that predicts whether irrigating with this quality of water will affect the soil structure.

Figure A6 Relationship between sodium adsorption ration (SAR) and electrical conductivity (EC) of irrigation water for prediction of soil structural stability (ANZECC-ARMCANZ, 2000).

As the electrical conductivity of the source water is not provided in the PCRP study, an EC of 1.5 dS/m was estimated based on source water data from the FIG study. A sodium adsorption ratio of 7 was calculated from the mean concentrations of sodium, calcium and magnesium in source water, according to Eq. 1 given in the Phase 1 guidelines (NRMMC–EPHC–AHMC, 2006):

Eq.1,

where the concentrations of cations are expressed in mg/L.


These results suggest that soil structural properties as affected by sodicity will depend on the soil properties and rainfall. These variables in relation to sodicity have not been investigated at the Perry Lakes site; however a comparison can be made with the ambient groundwater which is currently used for irrigation. Ambient groundwater at Perry Lakes has a SAR of 4 and an electrical conductivity of 1.6 dS/m (Table A5). These data superimposed on Figure A6 indicate the same results as for the source water quality. Since irrigating with ambient groundwater has not led to sodicity, it is unlikely that irrigating with the source water will produce a sodicity problem. The environmental consequences would be minor with local impacts contained to the site. Hence, the level of risk of sodicity from irrigating with the source water quality could be moderate; however additional work is needed to identify plant species and to determine their sodicity tolerance levels.

For aquatic ecosystems, the maximal risk assessment of salinity indicated a moderate risk (Table 10). The likelihood of the occurrence of salinity is almost certain because the source water exceeds the trigger value for electrical conductivity. The severity of the consequence is minor as it may be potentially harmful to the local ecosystem with local impacts contained to the site, leading to an overall moderate risk.


APPENDIX B. ADDITIONAL INVESTIGATIONS

i. Additional studies required At this time, the following Stage 2 investigations identified above have not been conducted:

1. a baseline survey of flora and fauna

2. pumping tests to determine aquifer transmissivity at the site;

3. recent water sampling of ambient groundwater and lake water quality;

4. geochemical modelling with ambient groundwater from the site to determine the likelihood of potential reactions between the source water and aquifer; and

5. transient groundwater flow and transport modelling.

The recommendations are to conduct a survey of flora and fauna to determine not only baseline conditions, but also to identify whether there are species of high conservation value to protect. To supplement the pumping test analysis conducted by Rich (2004), additional aquifer testing should be conducted in the vicinity of the proposed MAR site to assess the likelihood of fracture permeability and short-circuiting of wastewater flow toward the lakes.

ii. Further modelling work required The model described above was a first attempt to understand the relationship between infiltration volumes and water table response to assess broad design criteria. It is essential that predicted contours of the water table under the MAR scenario are analysed to identify the extent of the zone influenced by MAR where water quality impacts could occur and to consider existing bores in the area and their purpose. A transient, three-dimensional model to simulate the time-dependence of water levels in the aquifer and particle tracking to simulate conservative solute transport are needed based on the risk assessment. This modelling work is required to address more specific questions. These include:

1. How long would it take for water levels in the lakes to rise?

2. How sensitive are predicted water levels to changes in rainfall (i.e. seasonal and climate-related changes in rainfall)?

3. How sensitive are predicted water levels to pumping from irrigation bores at the Perry Lakes reserve?

4. How long would it take for the mound to dissipate if wastewater infiltration was temporarily halted (e.g. for maintenance, an electrical power disruption, or a leak in the distribution system)?

5. How far will the wastewater plume extend from the infiltration galleries toward East and West Lakes?

6. How sensitive are the rate and direction of migration of the wastewater plume toward the lakes to changes in recharge rates applied in the infiltration galleries?

7. (see below) What are the spatial distributions of chemicals and microbial pathogens in the aquifer as MAR continues over time?

8. Will an increase in the water table impact on Camel Lake and other wetlands?

9. How long will it take before the recharge plume discharges to the Indian Ocean, where along the coast, and at what dilution?

10. Under what conditions will the treated wastewater (source water) reach the lakes?


A further refinement is to construct a three-dimensional, transient transport model to predict movement of different constituents in the wastewater plume as they migrate at different rates through the aquifer. Non-reactive or conservative chemical species will migrate at a maximum rate of transport by advection and dispersion within the aquifer. This type of model will provide an estimate of the fastest transport times or minimum aquifer residence, which may be particularly useful for evaluating worse case scenarios of breakthrough of chemicals or microbial pathogens in the wastewater at particular points in the aquifer. If there are sufficient data, a further refinement is to add degradation and adsorption coefficients for individual chemical species in the wastewater to the solute transport model.

Obtaining suitable data sets for calibrating the transient solute transport model is not a trivial exercise. Tracer experiments are recommended to aid in calibrating the model of conservative solute transport. To calibrate transient groundwater flow would require modelling temporal changes in water table and matching to historical data. To fully calibrate a model of reactive solute transport would require considerable effort involving identifying suitable surrogates for certain reactive species or pathogens to realistically simulate adsorption and degradation.


REFERENCES ANZECC–ARMCANZ, 2000, Australian and New Zealand Guidelines for Fresh and Marine Water Quality. National Water Quality Management Strategy Paper no 4, Canberra, Australian and New Zealand Environmental and Conservation Council and Agriculture and Resource Management Council of Australia and New Zealand.

Beckwith Environmental Planning, 2006, In situ social values of groundwater-dependent features on the Gnangara Mound.

Bekele, E., S. Toze, B. Patterson, B. Devine, S. Higginson, W. Fegg, and J. Vanderzalm, 2009, Design and operation of infiltration galleries and water quality guidelines - Chapter 1, in S. Toze, and Bekele, E., ed., Determining the requirements for managed aquifer recharge in Western Australia. A Report to the Water Foundation. http://www.clw.csiro.au/publications/waterforahealthycountry/2009/wfhc-MAR-requirements-WA-Ch1.pdf

Bennelongia, 2008, Literature review and monitoring program for stygofauna in the Gnangara groundwater system. Report for the Department of Environment and Conservation, Report 2008/24.

Dames and Moore, 1992, Perry Lakes Environmental Management Study. Report prepared for the City of Perth, Report Number 15345-006-071, April 1992.

Davidson, W. A., 1995, Hydrogeology and groundwater resources of the Perth region, Western Australia: Bulletin 142, Western Australia Geological Survey.

Department of Environment, 2004, Perth Groundwater Atlas (Second Edition).

Department of Water, 2009, Strategic policy 1.01 - Managed aquifer recharge in Western Australia. Allocation and water quality management. Draft for public comment.

Department of Water, 2010, Draft approval framework for the use of non-drinking water in Western Australia: urban developments, Perth, Government of Western Australia.

Dillon, P., A. Kumar, R. Kookana, R. Leijs, D. Reed, S. Parsons, and G. Ingleton, 2009, Managed aquifer recharge - Risks to groundwater dependent ecosystems - A review. CSIRO Water for a Healhy Country Report to Land and Water Australia.

Drummond, A., 2010, Design and cost-effectiveness of infiltration galleries at Perry Lakes; Floreat: Honours thesis, University of Western Australia.

Environmental Protection Authority, 1993, Western Australian Water Quality Guidelines for Fresh and Marine Waters. EPA Bulletin No. 711. Environmental Protection Authority, Perth, Western Australia.

Estill & Associates, 2005, Study of groundwater-related aboriginal cultural values on the Gnangara Mound, Western Australia. Unpublished report prepared for the Department of Environment.

Gnangara Coordinating Committee, 2009, Gnangara sustainability strategy: draft for public comment, Government of Western Australia.

Government of Western Australia, 2006, State Planning Policy 2.9 Water Resources, Western Australian Planning Commission, Perth, Western Australia, in W. A. P. Commission, ed.

Government of Western Australia, 2007, State Water Plan.

Government of Western Australia, 2008, Better Urban Water Management.

Lugg, R., and W. A. Department of Health, 2009, Premier’s Collaborative Research Program (2005-2008): characterising treated wastewater for drinking purposes following reverse osmosis treatment. Technical Report, Department of Health [Perth, W.A.].


McFarlane, D., J. Simpson, E. Bekele, T. Smith, and S. Tapsuwan, 2007, Perry Lakes Aquifer Replenishment Proposal for the Town of Cambridge and WA Government Regulators. CSIRO Water for a Healthy Country National Research Flagship Proposal.

McFarlane, D., A. Smith, E. Bekele, J. Simpson, and S. Tapsuwan, 2009, Using treated wastewater to save wetlands impacted by climate change and pumping: Water Science and Technology, p. 213-221.

NRMMC-EPHC-NHMRC, 2009, Australian Guidelines for Water Recycling: Managing Health and Environmental Risks (Phase 2) Managed Aquifer Recharge, Canberra, Natural Resources Management Ministerial Council, Environmental Protection and Heritage Council and National Health and Medical Research Council.

NRMMC–EPHC–AHMC, 2006, Australian Guidelines for Water Recycling (Phase 1): Managing Health and Environmental Risks, Canberra, Natural Resources Management Ministerial Council, Environmental Protection and Heritage Council and National Health and Australian Health Ministers Conference.

PPK, 2000, Perry Lakes Reserve Environmental Management Plan. Consultancy Report by PPK Environment and Infrastructure for the Town of Cambridge.

Rich, J., 2004, Integrated Mass, Solute, Isotopic and Thermal Balances of a Coastal Wetland. PhD thesis Murdoch University, Western Australia. Thesis available for download at: http://perrylakes.info/.

Rodriquez C, Page D, McGuinness N, Weinstein P, Cook A and Devine B. 2009, Health risk assessment – Chapter 4, in S. Toze, and Bekele, E., ed., Determining the requirements for managed aquifer recharge in Western Australia. A Report to the Water Foundation. http://www.clw.csiro.au/publications/waterforahealthycountry/2009/wfhc-MAR-requirements-WA-Ch4.pdf

Smith, A. J., D. Pollock, and D. McFarlane, 2005, Opportunity for Additional Self Supply of Groundwater from the Superficial Aquifer, CSIRO Water for a Healthy Country Flagship [http://www.csiro.au/files/files/p7rt.pdf].

Tapsell, P., D. Newsome, and L. Bastian, 2003, Origin of yellow sand from Tamala Limestone on the Swan Coastal Plain, Western Australia: Australian Journal of Earth Sciences, p. 331-342.

Tapsuwan, S., G. Ingram, and D. Brennan, 2007, Valuing urban wetlands of the Gnangara Mound. Technical report, CSIRO: Water for a Healthy Country National Research Flagship.

Tapsuwan, S., Z. Leviston, and D. Tucker, 2009a, Sense of Place: Perth community attitude towards places of significance on the Gnangara Groundwater System. CSIRO: Water for a Healthy Country National Research Flagship, CSIRO: Western Australia.

Tapsuwan, S., R. Ranjan, D. McFarlane, and A. Elmahdi, 2009b, Economic and Social Values of Land and Water Uses on the Gnangara Groundwater System. Report Prepared for the Gnangara Taskforce, Department of Water, Western Australia. Gnangara Sustainability Strategy and CSIRO Water for a Healthy Country National Research Flagship Report.

Town of Cambridge, 2008, Water conservation plan submitted to the Department of Water, Western Australia.

Townley, L. R., J. V. Turner, J. F. Rich, and K. D. Wright, 1995, Preliminary report on the groundwater hydrology of Perry Lakes, prepared for the Town of Cambridge, CSIRO Division of Water Resources Consultancy Report No. 95/27, p. 61.

Water and Rivers Commission, 2000, Environmental Water Provisions Policy for Western Australia, Statewide Policy No. 5.

Water Corporation, 2009a, Subiaco Wastewater Treatment Plant.

Water Corporation, 2009b, Water Forever: Towards Climate Resilience.


Whelan, B. R., and N. J. Barrow, 1984, The movement of septic-tank effluent through sandy soils near Perth .2. Movement of phosphorus: Australian Journal of Soil Research, p. 293-302.

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Application of the Australian Guidelines for water ... · The Australian Guidelines for Water Recycling: Phase 2, Managed Aquifer Recharge were published on the website of the Environmental