Status of Groundwater Quality in the Cockburn Sound Catchment
Final Report to Cockburn Sound Management Council
M. G. Trefry, G. B. Davis, C. D. Johnston, A. G. Gardiner, D. W. Pollock and A. J. Smith
February 2006
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Status of Groundwater Quality in the Cockburn Sound Catchment
Status of Groundwater Quality in the Cockburn Sound Catchment
Final Report to Cockburn Sound Management Council
M. G. Trefry, G. B. Davis, C. D. Johnston, A. G. Gardiner, D. W. Pollock and A. J. Smith
CSIRO Land and Water February 2006
i Preface
The coastal resources of the Perth metropolitan area essentially define the lifestyle and culture of the majority of the population of Western Australia. Cockburn Sound is an iconic feature of this lifestyle, supporting a rich variety of commercial, industrial, defence, tourism and recreational uses for the broader community. However, the pressures on Cockburn Sound associated with urbanization and industrialization are increasing, and the local ecosystem is under stress. Recognizing this, the WA Government has established a regulatory and policy framework for managing the environmental values of Cockburn Sound. The Cockburn Sound Management Council (CSMC), established under the aegis of the WA Department of Environment, is charged with coordinating environmental management and planning to protect Cockburn Sound and its catchment.
The coordination role is essential in managing such a complex system. Already CSMC has developed an Environmental Management Plan and brokered agreements between Local Government Authorities, planners and environmental regulators. The present groundwater contamination study is commissioned by CSMC to report on the environmental state of the Cockburn Sound system. This and other studies will inform CSMC on the current environmental performance of the Cockburn Sound system. With respect to the present groundwater study, key tasks are to identify important groundwater contamination threats to the amenity and environmental quality of the Sound, to identify gaps in management performance and to recommend potential improvements in future management practice. To this end, the study has concentrated on a summary review of literature and data pertaining to groundwater quality in the Cockburn Sound catchment and related literature on land-use impacts on groundwater. The literature and data was freely contributed to the study by a range of industry, government and community groups and associations, allowing a reasonably complete assessment of the important groundwater quality issues in the catchment. That some management gaps are identified in this study is no particular criticism of the environmental regulators, planners or industry – the catchment itself is developing rapidly in terms of urbanization, land use change and major planning initiatives. In such a dynamic context it is normal to review and update management practices regularly.
However, it is important to understand that the capacity of any ecosystem to absorb stress is finite. Cockburn Sound itself is already under significant stress, so future planning for the Sound and its catchment must seek to balance the goals of economic and social development against environmental imperatives. This requires a greater level of consultation and cooperation between catchment stakeholders, and also requires advances in the scientific understanding of ecosystem processes in Cockburn Sound. Already a spirit of positive cooperation between major industry and CSMC is apparent, especially those companies sited along the Kwinana industrial strip, and relationships between CSMC and Local Government Authorities are strong. Regular community forums are also held by CSMC. Hopefully this study highlights areas where other important relationships could be strengthened, where management practices could be improved and where gaps in scientific knowledge are hindering the management of potential groundwater contamination threats to Cockburn Sound.
ii Status of Groundwater Quality in the Cockburn Sound Catchment
Executive Summary
Cockburn Sound Context Cockburn Sound is a marine ecosystem under stress from the pressures of both aquatic and terrestrial human activities. The Western Australian Government has acted to preserve Cockburn Sound for multiple uses, i.e. the Sound will support a balance of urban, industrial and environmental uses. As a societal response to the pressures facing Cockburn Sound, a system of environmental values has been developed for the Cockburn Sound ecosystem under the State Environmental (Cockburn Sound) Policy (SECSP). These values are protected by SECSP and are assessed against quantitative Environmental Quality Criteria (EQC) regularly.
Link to Groundwater Quality Seagrass growth and chlorophyll levels are important environmental indicators for Cockburn Sound. Previous scientific studies have drawn a link between these indicators in the seawater of the Sound, and nutrient (mainly nitrogen) levels discharged to the Sound from terrestrial sources. Thus groundwater quality (along with stormwater and industrial effluent quality) is an important factor for the health and sustainability of the Cockburn Sound ecosystem. In turn, this means that groundwater quality must be managed throughout the whole of the Cockburn Sound catchment.
Regulatory, Policy and Planning Framework SECSP establishes the basis on which Cockburn Sound is protected. Cockburn Sound Management Council (CSMC) has prepared an Environmental Management Plan for Cockburn Sound and its Catchment (EMP), which implements SECSP. There are no explicit terrestrial environmental values listed in SECSP; all management of terrestrial environmental issues is done under the EMP with the ultimate goal of protecting environmental values within the body of the Sound. The Environmental Protection Act and Regulations are applied across the catchment to license and regulate harmful emissions and discharges. The Contaminated Sites Act is expected to strengthen environmental management when it becomes operative. A Local Planning Policy has been adopted by the three Local Government Authorities (LGAs) and CSMC to ensure a mutual and coordinated approach to the management of Cockburn Sound. At the State level, major new planning initiatives, land use changes and redevelopments must gain environmental approvals from the Environmental Protection Authority. Garden Island is a Commonwealth property managed under the Environmental Protection and Biodiversity Conservation Act. The Australian Defence Force’s Good Neighbour Policy is also applied to environmental management of the island.
Major Planning Initiatives A range of significant initiatives are proposed for the catchment, including extensive port facilities and associated land reclamations along the coast, a major new heavy industrial precinct, a proposed large scale marina development and a projected doubling of population in the next few decades. These initiatives will be accompanied by a continuation of the sewage infill program, improved wastewater treatment and recycling, and a decline of intensive horticulture and semi-rural activities in the catchment as large areas of land are rezoned to urban land uses.
Managing Groundwater Contamination Industrial, commercial and governmental activities that pose a significant potential risk of contamination can be licensed as prescribed premises under Part V of the Environmental
iii Protection Act. There are presently 83 licensed premises within the Cockburn Sound catchment, including companies and organizations across the manufacturing, industrial and service sectors. Many of these premises are located close to the Cockburn Sound shore. Department of Environment monitors these premises for environmental performance and compliance with licence conditions.
The Superficial Aquifer The water table across the catchment is located within the Superficial Aquifer, a geologic zone extending typically to approximately 40 m below ground surface (although as much as 100 m deep in places) and containing unconsolidated sands and limestones. Groundwater flows readily through the Superficial Aquifer from east to west, tending north-west or even north near the Rockingham coast. Groundwater discharges to Cockburn Sound along the shoreline and along the floor of the Sound. Persistent contaminants entering the groundwater near the eastern margins of the catchment are likely to find their way, eventually, to Cockburn Sound. Travel times over this distance may potentially be 60 years or longer. The vast majority of groundwater contaminations in the catchment occur within the Superficial Aquifer, both on the mainland and on Garden Island. Deeper aquifer systems also have some contamination issues but these are considered to pose lesser risks to Cockburn Sound.
Survey of Potential Point Source Contaminations A total of 79 stakeholders were contacted as part of this study, including 32 operators of licensed premises. There were 14 stakeholders who did not respond, and a total of 50 operators of industrial/commercial premises took part voluntarily in the study. Contaminants of concern include nutrients, petroleum hydrocarbons, metals, pesticides and herbicides, phenols and solvents. Assessments of the licence conditions imposed by DoE on these premises (where appropriate) indicated that groundwater monitoring conditions did not always reflect the full suite of potential contaminants handled or stored at each premises. It was felt that too much reliance was placed on known instances of contamination for deciding the specific analytes to be monitored as part of license conditions, rather than a more precautionary approach based on potential risk of contamination. It was also found that discovery of significant groundwater contamination at a site was not always accompanied by groundwater management or remediation actions, especially for landfill sites.
Survey of Diffuse Contamination Groundwater quality (i.e. nutrient levels) monitoring at the catchment scale ceased within Cockburn Sound in 1999. There are no data sets of nutrient concentrations in the groundwaters available other than those contributed by industry under their licence conditions or as part of further investigations at their premises. Since the licensed premises are clustered near the coast, this data set is unsuitable for managing catchment-scale groundwater quality issues. Based on earlier studies on nutrient dynamics under urban developments elsewhere on the Swan Coastal Plain, it is prudent to anticipate that the planned initiatives for the catchment may lead to increased nutrient levels across the catchment. There is some evidence that this may already be happening. There is clear need for the establishment of a comprehensive and permanent catchment- scale water quality monitoring program.
Groundwater Contaminant Inputs to Cockburn Sound Recent assessments of net inputs to the Sound from groundwater, stormwater and industrial effluents have shown that direct industrial discharges have dropped dramatically over the past 20 years, and that groundwater inputs now dominate for a number of chemicals of concern. Despite these trends, the precision of estimates of groundwater contaminant inputs has not improved significantly over the last decade. This iv Status of Groundwater Quality in the Cockburn Sound Catchment
is largely due to the difficulty of characterizing the spatial and hydraulic properties of the Superficial Aquifer, especially the limestone formation. There is limited information on stormwater drainage inputs, although there is potential for contamination from this pathway.
Management Gaps and Recommendations Whilst there is significant evidence of integrated management and planning practice for the Sound, efficiency gains could be made by further promoting routine collaboration between DoE, planners and developers at all stages in the proposal development process. By exposing the proposal development process to environmental considerations at the earliest stage, there is less chance for conflicting views at the final environmental approvals stage. Recommendation R.1 It is recommended that CSMC request that the EPA consider including groundwater quality impact statements in all major planning environmental assessments for areas within Cockburn Sound and its catchment. Furthermore, it is recommended that the DPI and relevant local governments ensure that due consideration for groundwater impacts of development proposals is given at all stages of the planning approval process and that collaborative linkages with the DoE in this area are strengthened.
In our opinion, the special combination of demands and stresses facing Cockburn Sound warrants a higher level of environmental protection than is presently provided for under the SECSP. In particular, we consider that all prescribed premises close to the shoreline should be subject to a greater level of scrutiny than is currently the case. Recommendation R.2 It is recommended that CSMC consider the establishment of a Proximate Vulnerability Zone along the Cockburn Sound shoreline. All prescribed premises within the Zone should be required to institute at least the default groundwater monitoring program (see Section 6.2.2).
Along with this we recommend that DoE ensure that licence conditions are updated regularly to reflect changing environmental conditions in the catchment and site contamination. Recommendation R.3 It is recommended that CSMC request that the DoE re-examine the current practice of licence renewal and comprehensive review to ensure that updating of licence conditions relevant to environmental parameters reflects environmental trends in Cockburn Sound and its catchment.
In support of this recommendation, we propose a default suite of groundwater analytes be monitored at all prescribed premises in the Proximate Vulnerability Zone and at all licensed premises elsewhere in the catchment, and a minimum configuration of monitoring bores suitable for screening the Superficial Aquifer. Recommendation R.4 It is recommended that CSMC request that the DoE consider adopting the default suite of analytes as a minimum standard of groundwater monitoring at prescribed premises in the catchment. Recommendation R.5 It is recommended that CSMC request that the DoE consider developing a minimum groundwater monitoring configuration for prescribed premises in the Proximate Vulnerability Zone, requiring at least two bores (upgradient and downgradient of major waste handling and storage areas on site), with separate screens at the base of the Superficial Aquifer and at the water table in each bore. Samples from each screen should be
v tested for the default suite of analytes and reported to DoE on a 6 monthly basis, with all exceedances of licence conditions and/or marine trigger values noted.
In terms of assessing compliance, we recommend that annual inspections be made of premises, including physical visits by DoE inspectors. Recommendation R.6 It is recommended that CSMC request that the DoE consider that each licensed premises in the catchment and each prescribed premises in the Proximate Vulnerability Zone is inspected annually for compliance with environmental standards and licence conditions; each inspection should include a physical visit and appropriate reporting to file.
Activities falling outside the prescribed premises regulations still have potential to pose significant threats to groundwater quality. We recommend that a simple screening process be instituted at LGA level to inform small to medium sized enterprises (SMEs) of environmental issues and to feed into catchment-scale environmental management and planning. Recommendation R.7 It is recommended that CSMC and LGAs work together to develop a brief hazardous wastes survey for all new business registrations in the catchment. The resulting information should be compiled by LGAs into a spatial database for ready input to planning and environmental management activities at LGA and State Government levels.
There is potential for catchment-scale water quality issues to become dominant drivers of the Cockburn Sound ecosystem in the short to medium term. In order to anticipate this threat and to generate appropriate management interventions on a timely basis, we recommend the re-establishment of catchment scale groundwater monitoring. Recommendation R.8 It is recommended that CSMC request that the DoE/DoW consider re-establishing a regular groundwater quality sampling program across the catchment consisting of at least thirty (30) bores. Each bore should be screened separately at the water table and at the base of the Superficial Aquifer. This program should be given high priority so that adequate baseline information can be gathered before major redevelopments commence.
There are several groundwater plumes that contribute the bulk of the nitrogen (and potentially other chemicals of concern) to Cockburn Sound, yet monitoring is sparse. We recommend that focused monitoring programs be established for these with a view to better estimation of net discharge to the Sound, and for tracking the performance of plume management. Recommendation R.9 It is recommended that further investigation of the depth and width of the high priority nutrient plumes in the catchment be undertaken to better define plume dimensions, peak concentrations and mass fluxes discharging towards Cockburn Sound. Periodic monitoring would provide performance measures for management initiatives.
There is also no comprehensive plan for managing the highest priority plumes in the catchment. In concert with Recommendation R.8, we recommend that management plans be established for all high priority plumes. Recommendation R.10 It is recommended that management plans be developed for the most prominent plumes in the Cockburn Sound Catchment and performance criteria be established for reduction of chemical mass flux to Cockburn Sound.
vi Status of Groundwater Quality in the Cockburn Sound Catchment
DoE is presently working towards a rationalization and consolidation of its data holdings. This effort is crucial for efficient environmental management of Cockburn Sound and should be boosted. Recommendation R.11 It is recommended that CSMC request that DoE continue its efforts in spatial referencing of premises and licensing data with the goal to construct a single comprehensive database of groundwater monitoring data in the catchment.
The CSMC Report Card system has been well received in the community. We recommend that this system be extended to include explicit reporting on groundwater quality. Recommendation R.12 It is recommended that CSMC consider the development of a new Report Card for groundwater contamination in the catchment. Groundwater nutrient levels should be a key indicator of contamination state, but consideration should also be given to flux estimates. This data would largely flow from Recommendation R.8.
Science Coordination To address the challenges facing Cockburn Sound, there are complex management and science issues that need attention. Some of the science issues are described below. However, to underpin effective management decisions, it is clear that substantial resources are needed for research and investigation. To meet the required strategic research effort, it is recommended that a separate research centre be formed called the Cockburn Sound Environmental Systems Research Centre with a remit to commission, coordinate and direct strategic research activities that will underpin management decisions affecting Cockburn Sound. The Centre should seek to unite terrestrial, atmospheric and marine research to provide the best possible integrated research outcomes for Cockburn Sound, and potentially for other (national and international) urban/marine systems. The Centre would be a collaborative effort between research providers, CSMC and other interested parties. To be successful, core State Government funds would need to be provided to stimulate and advance strategic science for the Cockburn Sound catchment. Some funding would also be required to support Centre administration. Additional funding would be sourced through Federal Government funding mechanisms, and continue to be provided by industry and other avenues where specific issues need to be addressed. The Centre would have a catchment wide brief, in keeping with the wider Cockburn Sound ecosystem, and would receive formal strategic direction from Cockburn Sound stakeholders. One potential stakeholder may be a new technical advisory subcommittee of CSMC. Recommendation R.13 It is recommended that CSMC consider requesting State Government support for the establishment of a Cockburn Sound Environmental Systems Research Centre, with a remit to pursue strategic research and to provide research support for management decisions affecting the wider Cockburn Sound ecosystem, especially with respect to terrestrial influences and impacts on the Sound. It is also recommended that the terms of reference and structure of the new Centre are to be decided by CSMC in consultation with stakeholders.
Science Gaps In terms of groundwater quality, there are four significant gaps in the current scientific understanding of the Cockburn Sound ecosystem. These gaps are impeding the development of precise contamination assessment and remediation strategies for the Sound.
vii Spatial and Hydraulic Properties of the Superficial Aquifer The lack of detailed information on the spatial properties of the Tamala Limestone unit within the Superficial Aquifer is an impediment to accurate estimations of groundwater travel times and of movement of chemicals towards Cockburn Sound. This is fundamental to assessing risks and designing remediation strategies; no significant progress has been made in understanding the hydraulics of groundwater flow in this aquifer in decades. In addition, an adequate understanding of geochemical and other controls on the persistence and discharge of plumes to Cockburn Sound is lacking.
Relationships between Groundwater Contamination and Marine Ecosystem Response There is a gap in the present scientific understanding of the relationships between the various classes of groundwater contamination and the resulting impacts to receiving marine ecosystems. This science gap means that rigorous EQC trigger values for contaminants in groundwater are lacking, and that EQC values pertinent to the receiving waters themselves are used instead. This may potentially be an unreasonable constraint on minimum quality standards for groundwater discharging to marine environments, especially for contaminants that may degrade rapidly in marine sediments or environments.
Stormwater Contamination Pathways to Cockburn Sound There is insufficient understanding of the potential risks to Cockburn Sound presented by stormwaters arising from the catchment. It is known that stormwaters can contain high levels of chemicals of concern, however the actual loads discharging to the Sound each year through this pathway are not well understood. The impacts of contaminated stormwaters on the lakes and wetlands that are part of the stormwater drainage network are also not well understood.
Nutrient Cycling in the Sediments Currently, there is uncertainty as to the relationship between nutrient inputs to the Sound and chlorophyll readings, which are used as a surrogate index of the health of the Sound. This may be due to a lack of understanding of nutrient cycling in the basal sediments of the Sound. This situation needs to be clarified.
viii Status of Groundwater Quality in the Cockburn Sound Catchment
Contents
Preface ...... ii
Executive Summary ...... iii
Contents...... ix
List of Figures...... xii
List of Tables ...... xiii
Glossary and Abbreviations...... xiv
Acknowledgments...... xvii
1 The Cockburn Sound Groundwater Quality Study ...... 1 1.1 Terms of Reference and Study Area...... 3 1.1.1 Terms of Reference ...... 3 1.1.2 Study Area ...... 4 1.2 Structure of this Report ...... 9 2 State of Groundwater in Cockburn Sound Catchment...... 9 2.1 Hydrogeology of Cockburn Sound ...... 9 2.1.1 Regional Setting...... 9 2.1.2 Superficial Formations ...... 14 2.1.2.1 Tamala Limestone...... 14 2.1.2.2 Ascot Formation ...... 15 2.1.2.3 Gnangara Sand...... 15 2.1.2.4 Bassendean Sand...... 15 2.1.2.5 Cooloongup Sand ...... 15 2.1.2.6 Becher Sand ...... 15 2.1.2.7 Safety Bay Sand ...... 15 2.1.3 Underlying (Subcrop) Formations...... 15 2.1.3.1 Kardinya Shale Member...... 18 2.1.3.2 Pinjar and Wanneroo Members...... 18 2.1.3.3 Rockingham Sand...... 18 2.1.4 Superficial Aquifer...... 18 2.1.4.1 Influence of Sea Level Variation on Groundwater Levels...... 19 2.1.4.2 Seawater Intrusion within the Superficial Aquifer ...... 22 2.1.5 Rockingham Aquifer...... 23 2.1.6 Confined Aquifer System ...... 23 2.1.7 Groundwater Travel Times ...... 24 2.2 Fundamentals of Groundwater Contamination ...... 25 2.2.1 Land Use Impacts on Groundwater Quality...... 25 2.2.1.1 Potential Urban Impacts ...... 26 2.2.1.2 Potential Chronic Urban Impacts...... 27 2.2.1.3 Potential Horticultural Impacts...... 27 2.2.1.4 Potential Industry Impacts ...... 28 2.2.1.5 Potential Landfill Impacts ...... 28 2.2.1.6 Potential acid sulphate soil Impacts ...... 28 2.2.1.7 Potential Stormwater Impacts ...... 29 2.2.2 Classes of Contaminants and their Properties ...... 29 2.2.2.1 Nutrients...... 30 2.2.2.2 Metals and Acids...... 30 2.2.2.3 Petroleum Hydrocarbons...... 30
ix 2.2.2.4 Chlorinated Hydrocarbons ...... 32 2.2.2.5 Pesticides and Herbicides...... 32 2.2.2.6 Endocrine Dispruptors ...... 32 2.2.2.7 Pathogens...... 32 2.2.3 Groundwater Contaminant Processes...... 33 2.2.3.1 Groundwater Flow...... 33 2.2.3.2 Hydrodynamic Dispersion ...... 34 2.2.3.3 Dissolution ...... 34 2.2.3.4 Volatilisation...... 34 2.2.3.5 Sorption ...... 34 2.2.3.6 Biodegradation...... 35 3 Pressures on Cockburn Sound Groundwater ...... 35 3.1 Development In Cockburn Sound...... 35 3.1.1 First Inhabitants...... 35 3.1.2 European Settlement ...... 36 3.1.3 Environmental Impacts...... 36 3.1.4 Urban Development ...... 39 3.1.5 Industrial Development ...... 39 3.1.6 Groundwater – the Hidden Input...... 40 3.2 Groundwater Quality in the Catchment...... 41 3.2.1 Nutrient Fluxes to Cockburn Sound ...... 41 3.2.2 Background Nutrient Levels...... 42 3.2.2.1 Background Water Quality Scenarios ...... 50 3.2.3 Assessing Human Impacts...... 51 3.3 Instances of Site Contamination...... 51 3.3.1 Use and Monitoring of Groundwater ...... 52 3.3.2 Analytes Monitored ...... 54 3.3.3 Screening and Location of Monitoring Wells...... 57 3.3.4 Identified Incidences of Groundwater Contamination ...... 58 3.3.5 Groundwater Management ...... 59 3.3.6 Threats to Cockburn Sound ...... 61 3.3.6.1 Nitrogen Species...... 62 3.3.6.2 Petroleum Hydrocarbons ...... 62 3.3.6.3 Trace Metals ...... 62 3.3.6.4 Biocides ...... 62 3.3.6.5 Caustic Solutions ...... 63 3.3.6.6 Saline Species ...... 63 3.3.7 Limitations of the Survey...... 63 4 Management Responses to Groundwater Quality ...... 65 4.1 Regulatory Environment...... 65 4.1.1 United Nations Convention on Biological Diversity 1993...... 65 4.1.2 Australian Guidelines for Establishing the National Reserves System 1999...... 66 4.1.3 National Environment Protection Council Act 1994 ...... 66 4.1.4 Environmental Protection and Biodiversity Conservation Act 1999...... 67 4.1.5 WA Environmental Protection Act 1986...... 67 4.1.6 WA Water Acts...... 68 4.1.7 WA Contaminated Sites Act 2003...... 69 4.1.8 WA Environmental Protection (Unauthorised Discharges) Regulations 2004...... 69 4.1.9 WA Environmental Protection (Controlled Waste) Regulations 2004...... 70 4.2 Land Planning Policy and Jurisdictions ...... 70 4.2.1 Jurisdictions ...... 71 4.3 Environmental Conditions of Cockburn Sound ...... 73 4.3.1 Environmental Values and Quality Objectives...... 73 4.3.2 Environmental Quality Guidelines and Standards (EPA, 2005)...... 73 4.3.3 Trigger Values (ANZECC/ARMCANZ, 2000)...... 74 4.3.4 Assessing Groundwater Impacts ...... 76 4.4 Environmental Management of Cockburn Sound ...... 77 4.4.1 Policy, Planning and Management Documents ...... 77 4.4.2 Memorandum of Understanding between LGAs and CSMC ...... 78 x Status of Groundwater Quality in the Cockburn Sound Catchment
5 Monitoring Groundwater Quality...... 78 5.1 Whole-Of-Community Interests...... 78 5.1.1 Catchment Scales...... 79 5.1.2 Point Scales ...... 80 5.2 Major Point Source Risks to Cockburn Sound ...... 81 5.2.1 BHP Billiton/WMC KNR ...... 82 5.2.2 CSBP ...... 84 5.2.3 Alcoa ...... 85 5.2.4 Water Corporation – Northern Harbour/Woodman Point...... 86 5.2.5 Nagata (former Love Starches site)...... 86 5.2.6 FPA/HIsmelt/LandCorp...... 87 5.2.7 Summit Fertilizers ...... 87 5.2.8 BP Refinery Kwinana ...... 88 5.2.9 DoD - HMAS Stirling ...... 88 5.2.10 Doral Specialty Chemicals ...... 89 5.2.11 Coogee Chemicals...... 89 5.2.12 FPA - United Farmers Cooperative Lease...... 90 5.2.13 CIK/Nufarm ...... 90 6 Management Gaps and Research Opportunities ...... 90 6.1 Integrated Planning Practices ...... 91 6.2 Proximate Vulnerability Zone ...... 91 6.3 Licence Conditions...... 93 6.3.1 Regular Reviews...... 93 6.3.2 Default Suite of Analytes...... 94 6.3.3 Minimum Monitoring Requirements For Sites...... 95 6.4 Inspections of Prescribed Premises...... 96 6.5 Unregulated Sites ...... 96 6.6 Groundwater Quality Monitoring...... 97 6.6.1 Catchment Scale Monitoring...... 97 6.6.2 plume Monitoring ...... 98 6.7 Information Management ...... 99 6.7.1 Prescribed and Non-Prescribed Premises Listings ...... 99 6.7.2 Community Involvement Practices...... 100 6.8 Cockburn Sound Research...... 100 6.8.1 Science Gaps...... 101 6.8.1.1 Hydrogeological Characterization and Discharge Mapping...... 102 6.8.1.2 Biogeochemical Transformations in the Hypoaktic Zone...... 103 6.8.1.3 Stormwater Contamination Pathway ...... 103 6.8.1.4 Nutrient Cycling in the Sediments ...... 104 References...... 105
Agreements, Conventions, Acts and Regulations ...... 111
Appendix 1: Risk Methodology ...... 113
Appendix 2: Licensed Prescribed Premises ...... 115
Appendix 3: Stakeholder Contacts ...... 117
xi List of Figures Figure 1.1: The setting of Cockburn Sound between the mainland and the partly submerged Pleistocene dune system offshore. Five Fathom Bank is the major submerged ridge line to the west of Garden Island. Dredged channels across Parmelia Bank are visible at the northern entrance to the Sound. LandSat7 satellite image taken on 5 February 2003, enhanced by WA Department of Land Information Satellite Remote Sensing Service...... 2 Figure 1.2: Cockburn Sound Management Council boundary (black line). For the purposes of this Study, the boundary is enlarged to encompass the eastward draining catchments of Garden Island. Green lines indicate local government boundaries; red lines indicate major roads. Image supplied by Cockburn Sound Management Council...... 5 Figure 1.3: Locality map and strategic developments planned for the South-West Metropolitan Sector. Data supplied by WA Department of Planning and Infrastructure, see WAPC [2005]. See facing page for information on map symbols...... 6 Figure 1.4: Coastal developments planned for Cockburn Sound, together with the new extension of the CSMC boundary in Owen Anchorage. Data supplied by WA Department of Environment...... 8 Figure 2.1: Surface expression of the superficial geological formations. Data supplied by WA Department of Industry and Resources...... 10 Figure 2.2: Superficial groundwater flow areas. Isopotentials are contoured at 1 m intervals. Cross sections A, B and C are relevant to Figure 2.4. Data supplied by WA Department of Environment...... 11 Figure 2.3: Subcrop geological formations underlying the superficial formations. Data supplied by WA Department of Environment...... 12 Figure 2.4: Hydrogeological cross sections through Cockburn Sound and Garden Island; section lines are indicated on Figure 2.2...... 13 Figure 2.5: Stratigraphic sequence of superficial formations; numbers in parentheses indicate maximum thickness of units...... 16 Figure 2.6: Tamala Limestone exposed (above the water table) in a limestone quarry...... 16 Figure 2.7: Groundwater from Tamala Limestone discharging at high rate from solution channels into a dewatered excavation...... 17 Figure 2.8: Safety Bay Sand at the shoreline of Cockburn Sound near Northern Harbour...... 17 Figure 2.9: Estimated saline wedge thickness distribution. Groundwater isopotentials are contoured at 1 m intervals. Isopotential and conservation category data supplied by WA Department of Environment...... 21 Figure 2.10: The Lake Richmond Drain. CSIRO photo taken November 2005...... 31 Figure 3.1: Aerial photograph of the Woodman Point munitions store. Image scanned from a WA Department of Environment photo taken in 1984...... 37 Figure 3.2: Aerial photograph of an intense algal bloom in Cockburn Sound during the summer of 1973-74. Image reproduced from a scan of Plate 11 of DoCE [1979]...... 38 Figure 3.3: Most recent sampling for nutrients by DoE referenced by location in the Cockburn Sound catchment. Data supplied by DoE from the WIN database. Monitoring bores operated by industry and other stakeholders in the catchment are not shown...... 43 Figure 3.4: Measurements of oxides of nitrogen levels for the Cockburn Sound catchment. Data supplied by DoE and Water Corporation. The ANZECC/ARMCANZ marine trigger value is 5 μg/L...... 48 Figure 3.5: Measurements of ammonia levels for the Cockburn Sound catchment. Data supplied by DoE and Water Corporation. The ANZECC/ARMCANZ marine trigger value is 5 μg/L...... 49 Figure 3.6: Locations of premises surveyed or relevant to this study. Location data supplied by WA Department of Environment and Water Corporation...... 53 xii Status of Groundwater Quality in the Cockburn Sound Catchment
Figure 5.1. Highest priority plumes from point source contaminations, identified from data supplied by participating industries and agencies...... 83
List of Tables Table 2.1: Estimated hydraulic properties of the Superficial Aquifer. Symbols and dimensions: n, porosity [-]; K, saturated hydraulic conductivity [m.d-1]; B, aquifer saturated thickness [m]; T = kB, aquifer transmissivity [m2.d-1]; S, aquifer storage coefficient [-]...... 20 Table 3.1: Estimated nutrient discharges to Cockburn Sound from groundwater...... 41 Table 3.2: Historical nutrient data for untreated groundwater extracted from Water Corporation production bores at Jandakot Mount. Concentrations are specified in units of μg (N)/L for combined NO2 and NO3 species. Underlined terms indicate instances where the six-year value is greater than or equal to the corresponding lifetime value. Data supplied by Water Corporation...... 44 Table 3.3: Historical nutrient data for untreated groundwater extracted from Water Corporation production bores at Jandakot Mount. Concentrations are specified in units of μg (N)/L for NH3 (ammonia). Underlined terms indicate instances where the six-year value is greater than or equal to the corresponding lifetime value. Data supplied by Water Corporation...... 45 Table 3.4: Historical nutrient data for groundwater extracted from DoE/WIN monitoring bores within the Cockburn Sound catchment. Concentrations are specified in units of μg (N)/L for total nitrogen oxides (NO2+NO3) and for NH3,4 (ammonia/ammonium species) over the period February 1994 – April 1998. a bores for which nitrogen oxides outlier readings of 1000 μg/L were removed; b single reading; c ignoring Cockburn Salt location. Data supplied by Department of Environment...... 46 Table 3.5: Hypothetical nutrient discharges to Cockburn Sound from background concentrations in groundwater. Scenarios assume that groundwater of the indicated quality is discharging to Cockburn Sound along the full 13.7 km length of shore. Nitrogen Species is defined as the sum of NO2, NO3 and NH3 concentrations. ANZECC/ARMCANZ trigger values; NHMRC drinking water guidelines...... 50 Table 3.6: Groundwater use, monitoring and management...... 55 Table 3.7: Summary of groundwater monitoring undertaken...... 56 Table 3.8: Identified contaminants in groundwater...... 60 Table 3.9: Premises with a high priority of future assessment...... 64 Table 4.1: Environmental Values and Environmental Quality Objectives for Cockburn Sound...... 73 Table 4.2: Default trigger values for some physical and chemical stressors for slightly disturbed inshore marine ecosystems in south-west Australia [ANZECC/ARMCANZ, 2000]...... 74 Table 4.3: Default trigger values for some physical and chemical stressors for slightly disturbed freshwater lake and reservoir ecosystems in south-west Australia [ANZECC/ARMCANZ, 2000]. .75 Table 4.4: Drinking water guideline values for some water quality indicators [NHMRC, 2004]...... 75 Table 5.1: Priority plumes identified from data supplied by participating industries and agencies..82 Table A1.1: Priority chemicals...... 114 Table A1.2: Priority sites and instances, based on contributed information...... 114
xiii Glossary and Abbreviations
Abstraction Removal of water from the aquifer. Ameliorate Reduce harmful conditions. Ammonia/Ammonium A chemical compound consisting of nitrogen and hydrogen. Ammonium is the predominant species dissolved in water. Ammonia is the gaseous form. Analytes Substances to be measured or detected. Anions Negatively charged atoms or molecules. Aquifer An underground zone of soil, sediments or rock that yields water. This water is then termed groundwater. If all the pore spaces in the aquifer are filled with groundwater, the aquifer is said to be saturated. Aquitard An underground zone of soil, sediments or rock that retards the flow of water. Shallow and deep aquifers are typically separated by aquitards. Attenuated Reduced, often by chemical or biological reactions. Biodegradation When microbes consume or transform contaminants. Biota The local population of living organisms. Bivalve A type of mollusc. Carcinogenic Able to induce cancer. Cations Positively charged atoms or molecules. Chlorophyll a A member of the chlorophyll class of green pigments that assist organisms to photosynthesize. Used as an indicator of eutrophication in Cockburn Sound. Conductivity [Hydraulic] A measure of how easily groundwater flows through an aquifer. Conductivity [Electrical] A measure of how easily electric current flows through a medium. Confined Aquifer System Any saturated aquifer that is capped by a layer impervious to groundwater flow. Cretaceous The period between 140 million years and 65 million years ago. CSMC Cockburn Sound Management Council Denitrification A process whereby nitrates and nitrites are converted to nitrogen gas and water. Depositional To do with the way geological sediments are deposited to form layers. Diffusion A natural process whereby heat or chemical concentrations slowly spread out and equalise. Dispersion The process whereby plumes gradually spread out and mix with uncontaminated groundwaters, includes effects of diffusion. Dispersivity An aquifer property governing the spatial range over which plumes mix with uncontaminated groundwater. Important in assessing dispersion. Dissolution When a chemical species dissolves into a fluid. DoD Department of Defence (Federal Government). DoE Department of Environment (WA Government). DoH Department of Health (WA Government). DoW Department of Water (WA Government). Effluent A fluid release, e.g. from an industrial process. Electron A negatively charged particle, the basis of electric current. Endocrine [disruptors] A chemical species that mimics endocrine (hormonal) features. These can lead to hormonal dysfunction in animals, including gender abnormalities. Epiphyte A plant which naturally grows on another plant without deriving any nourishment from the supporting plant. EQC Environmental Quality Criteria. EQG Environmental Quality Guideline. EQO Environmental Quality Objective. EQS Environmental Quality Standard. EMP Environmental Management Plan. Episodic To do with events that happen occasionally and in short bursts. EPUDR The WA Environmental Protection (Unauthorised Discharges) Regulations (2004). Eutrophication An oversupply of nutrients in a water body, causing abnormal rise in algae populations. Eutrophiers Those nutrients primarily responsible for eutrophication. Facies A classification of minerals or rock types based on appearance, origin and condition. Friable Readily crumbled, brittle. xiv Status of Groundwater Quality in the Cockburn Sound Catchment
Flux The amount of a substance passing through a unit area per unit time, e.g. a water flux of 10 litres of water per square metre per day. Geomorphology Study of types of geological formations. Groundwater Water that exists and moves in the soil and rock beneath the ground surface. Groundwater is replenished by precipitation and can interact with oceans, lakes and rivers. Groundwater presently supplies almost 60% of Perth’s total water use each year. Groundwater Receptor Something that receives or uses groundwater, e.g. lakes, trees, humans. Hydraulic Gradients Slopes in the groundwater elevation or pressure, such as the slope of the water table. Hydrodynamic To do with groundwater (or other water) movement. Hydrogeology The branch of geology that studies groundwater distribution and role. Hydrostatic To do with groundwater states in equilibrium with gravity. Hypoaktic [zone] The part of the aquifer immediately adjacent to (within a few metres) a beach or shore line with a salty sea or ocean. Hyporheic The part of an aquifer immediately adjacent to (within a few metres) of a freshwater stream, river or lake. Inorganic Chemical species not predominantly consisting of carbon, e.g. chemicals of mineral origin. Interdunal Between dunes. Isopotential A line connecting locations of equal groundwater pressure or elevation. Isotopic [technology] To do with isotopes, atomic elements with different numbers of neutrons. Used to track movement of chemicals in groundwaters. Jandakot Mound A prime source of potable water supplies for Perth, located to the north-east of the catchment boundary. Jurassic The period between 210 million years and 140 million years ago. KIC Kwinana Industries Council. LGA Local Government Authority. Leachate Fluids that move downwards through soils to groundwater taking contaminants with them, (often produced by landfills and tailings facilities). Limonite A type of common, yellowish-brown to black iron oxide minerals. Lithological To do with the classification of rocks according to colour, grain size, hardness and mineral composition. Lysimeter A device buried in the ground to measure downward movement of water in the soil. Macropore A large void inside an aquifer through which groundwater can flow rapidly. Metabolites Chemical species that are produced by microbes as by-products of consumption or metabolism. NEPC National Environment Protection Council. NEPM National Environment Protection Measure. Nutrient Discharge Flux The amount of nutrients released per unit area per unit time, e.g. kilograms of nitrogen per square metre per day. Oxidation The process where a chemical species combines with oxygen, or more generally where a molecule loses electrons. Pathogens Organisms that cause disease. Permeable Conductive or transmissive to water. pH A measure of the acidity or alkalinity of a solution. pH values range from 0 (highly acidic) to 14 (highly alkaline). A pH value of 7.0 indicates neutrality. Physico-chemical Describing combinations of physical and chemical effects and phenomena. Pleistocene The period between 1.6 million and 10 thousand years ago. Plume A contaminated zone in groundwater originating from a source of pollutants. Plumes may be very small, or up to several kilometres long or more. Porewater Fluids extracted from aquifer pore spaces. Porosity A measure of the amount of space between grains of rock and sand in the aquifer. Potable [quality] Water of a standard for human consumption. Precipitation The falling to earth of any form of water (rain or snow or hail or sleet or mist). Preferential Pathways Highly conductive zones and channels in aquifers. Quaternary The period between 1.8 million years ago and the present. Recharge Flow of water to an aquifer from above, often from precipitation.
xv Remediation Activities that reduce or eliminate harmful impacts of contamination. Salt Wedge The zone of salt water extending inland from the beach, usually at the bottom of the Superficial Aquifer. SECSP State Environmental (Cockburn Sound) Policy. SME Small to medium sized enterprise. Sorption The process whereby a chemical species sticks to a surface or material. Stratigraphic To do with the layering of rocks and sediments on top of each other. Stormwater Precipitation runoff that collects in drains and basins. Subcrop The upper surface of a lower layer, e.g. the Tamala Limestone subcrops the Safety Bay Sand in some areas. Superficial aquifer The aquifer that contains the water table, the aquifer bounded above by the ground surface. Surfactants Chemical species that alter the wetting properties of other substances. TBT See Tributyltin. Tertiary The period between 65 million years and 1.8 million years ago. Tidal Efficiency The ratio of ocean tide amplitude to groundwater head amplitude in a neighbouring aquifer. Toxicant A substance that causes harm to living organisms. Transmissivity A measure of an aquifer’s ability to transmit groundwater flow. Transmissivity is the product of the aquifer thickness with the aquifer hydraulic conductivity. Tributyltin An active organic-tin (organotin) compound used in marine antifouling paints; commonly abbreviated to TBT. Trigger Value An environmental quality criterion which, if exceeded, triggers investigation of potential environmental threat. Unconfined Aquifer An aquifer with a free water table. Unconformably Adjacent geological strata that do not conform to the geological time sequence are said to represent an uncomformity. Vertical Stratification The separation of contaminants in the vertical direction, e.g. a zone of contamination at the water table, and a second zone at the bottom of the aquifer. Volatilisation When a chemical species vaporises, or moves into a gas phase.
xvi Status of Groundwater Quality in the Cockburn Sound Catchment
Acknowledgments
This report reflects the contributions of many people committed to the future of Cockburn Sound. The CSIRO Study Team wishes to thank all those who helped, recognizing the long list of companies, organisations, associations, corporations and Federal, State and Local government agencies and authorities. Details of the entities that contributed to or took part in this Study are provided in Appendix 3. The Study itself was funded jointly by Cockburn Sound Management Council (CSMC), WA Department of Environment (DoE) and Kwinana Industries Council (KIC). The Cockburn Sound Groundwater Contamination Project Team, comprising Heidi Bucktin (Project Leader, CSMC/DoE), Megan McGuire (CSMC/DoE), Bart Houwen (CSMC/Community Networking Inc), Joanne Wann (DoD), Cameron Schuster (CSMC/KIC/CSBP) and Hamid Mohsenzadeh (DoE), is thanked for its guidance and direction.
Particular thanks are due to staff of DoE who gave great professional assistance in locating documents and data sets. DoE staff located at the Kwinana office, at Westralia Square and at the Hyatt Centre have all contributed significantly to the progress of the Study. WA Department of Planning and Infrastructure (DPI) also made data available to the Study, as did Water Corporation (WC), WA Department of Health (DoH), WA Department of Industry and Resources (DoIR) and Australian Department of Defence (DoD). KIC was a reliable source of liaison and assistance to the Study Team in the complex task of sourcing industry data. CSMC itself provided able support to the conduct of the Study; special thanks are due to Heidi Bucktin and staff at the Rockingham office for helping us past many obstacles.
The Study Team gratefully acknowledges extensive and informative conversations with the following individuals: Paul Whincup (ERM); Neville Blesing, Mike Lambert (Parsons Brinckerhoff, acting on behalf of industry clients); Peter McKenzie, Doug Smith and Kumar Vadivale (Town of Kwinana); Paul Nielsen, Owen Gunn and Rod Fielding (City of Rockingham); Chris Parlane and Paddy Strano (City of Cockburn); Paul Rosair, Declan Morgan, Hamid Mohsenzadeh, Rob Holmes, Steve Appleyard, Philip Hine, Carly Chor, Paul Byrnes, Caitlin McLennan (DoE); Joanne Wann (DoD); Jim Turley (WA Vegetable Growers Association); Jim Dodds, Neil McGuinness, Nathan Major and Walter Arrow (DoH); John Keesing (CSIRO/CSMC); Mark Pagano (Recfishwest); George Trefry (Kwinana Industries Forum), Phil Jennings (Conservation Council of WA); Rai Kookana, Don MacFarlane, Trevor Bastow, Elise Bekele (CSIRO). The friendly professional assistance of the following people is also acknowledged: Trudy Parker, Hannah Wardecki, Rose Lerch, Mike Lane, Carmel Staniland, Lisa Smith, Nick Duncan, (DoE); Gary Ash, Mark Nener, Guy Watson and David Luketina (CSMC/WC); Eugene Ferraro, Anna Piscicelli and Debbie Clifford (DPI); Peter Sanders (DLI); Heidi Bucktin, Megan McGuire and Chris Coffey (DoE/CSMC); Cameron Schuster, Debbie Hoey (KIC); Carolyn Oldham and Alicia Loveless (UWA); Anne McKenzie and Fred Van Dijk (CSIRO).
CSIRO Study Team Dr Mike Trefry Study Leader Dr Greg Davis Contaminant hydrology, remediation, industry liaison Mr Colin Johnston Monitoring assessments, risk weighting, database Ms Angela Gardiner Project coordination, records Mr Daniel Pollock Spatial data analysis Dr Tony Smith Hydrogeology, surface water – groundwater interaction
xvii
Status of Groundwater Quality in the Cockburn Sound Catchment
1 The Cockburn Sound Groundwater Quality Study
The majority of the human population of Western Australia resides in the Perth metropolitan region in the south-west of the state. Largely for aesthetic and other lifestyle reasons, this settlement tends to be focussed around the surface waters of the Swan- Canning estuary and the sandy beaches of the Indian Ocean. The ocean frontages are sheltered from hostile seas by a line of submerged reefs and island outcrops, promoting strong recreational and industrial connections between the human community and its offshore environment.
Garden Island is an important feature of this coastal system. The island is approximately 15 km long and only a few kilometres wide for much of its length. Garden Island extends north to south about 9 km from the mainland shore, sheltering a 16 x 9 km body of water called Cockburn Sound, located approximately 20 km south of the Swan River entrance, at Fremantle (Figure 1.1). The Sound has gently shelving margins and a deep central basin (to 22 m below mean sea level).
Because of its proximity to major population centres and its usually placid waters, Cockburn Sound now supports a range of recreational, urban and industrial activities, making it the most intensively used marine embayment in Western Australia. Examples of the activities supported by the Sound include recreational swimming and boating, aquaculture and fishing industries, and industrial and naval shipping. Cockburn Sound also experiences the pressures associated with on-shore industrial, semi-rural and urban developments, including burgeoning human populations, increasing heavy industrial activities, horticultural pursuits and the disposal of treated wastes.
After deterioration of water quality in the Sound in the 1970s it was recognized that the capacity of Cockburn Sound to withstand such pressures was limited. In the following decades, State governments instituted management measures to safeguard the environmental values and general amenity of the Sound. Through coordination of planning and management, general environmental indicators in Cockburn Sound were stabilised in the 1980’s and 1990’s, although some features have not been restored to the pre-industrial state. For example, it is estimated that 80% of the natural seagrass meadows of the Sound were lost by the mid-1970’s and there is little evidence of regrowth today despite twenty years of active environmental management of the Sound.
The Cockburn Sound Management Council (CSMC) was formed by the Western Australian Government in 2000 to coordinate environmental management and planning for the Sound and its catchment. CSMC can use environmental quality objectives (EQOs) and environmental quality criteria (EQCs) developed by the WA Environment Protection Authority (EPA) as metrics for the Environmental Management Plan (EMP), published this year [CSMC, 2005]. However, CSMC also needs to gather regular information on the environmental status of Cockburn Sound to inform the environmental planning process. This data gathering is done through the auspices of the environmental monitoring and compliance activities in the Sound conducted by WA Department of Environment (DoE), and through the participation of other stakeholders (companies, associations, community groups, state and local government authorities). On occasions, CSMC commissions focussed studies on key environmental aspects of the Cockburn Sound. One particularly significant study was “The State of Cockburn Sound: A Pressure-State-Response Report”
1
Figure 1.1: The setting of Cockburn Sound between the mainland and the partly submerged Pleistocene dune system offshore. Five Fathom Bank is the major submerged ridge line to the west of Garden Island. Dredged channels across Parmelia Bank are visible at the northern entrance to the Sound. LandSat7 satellite image taken on 5 February 2003, enhanced by WA Department of Land Information Satellite Remote Sensing Service.
2 Status of Groundwater Quality in the Cockburn Sound Catchment
[DAL, 2001], which identified areas where the environmental management of the Sound could be improved, including reduction of nutrient loadings and tributyltin contamination.
The same report presented evidence that nutrient fluxes to the Sound from heavy industry had stabilised or declined since the 1980’s, and that a significant proportion of the seawater nitrogen levels in the Sound resulted from nutrient cycling in the bed sediments. Nevertheless, recent plans for extensions of the heavy industrial facilities into the Hope Valley-Wattleup area [WAPC, 2000], together with projections of population increases of up to 30% or more in the catchment through planned re-zoning and urbanization, have raised concerns that groundwater nutrient loads and general groundwater quality throughout the catchment need more careful study. This was reflected in the EMP, which identified contamination from groundwater as a key issue.
CSMC commissioned the present report to inform the Council and stakeholders on the current state of groundwater contamination in the Cockburn Sound catchment, and on opportunities for improving the environmental management practices for the Sound. This report delivers this information in the standard Pressure-State-Response format [OECD, 1993]. This format focuses on the environmental state of a system, on the pressures imposed on the system by natural or human processes, and on the management and/or societal responses that may be employed to maintain the desired environmental values of the system.
In succeeding sections, this report will summarise available data on groundwater contamination instances within the Cockburn Sound catchment (the state of the catchment). The report will consider the most significant actual and potential pressures on the catchment and will finally discuss suitable environmental management responses to these pressures and suggest opportunities for improved management practices available under the existing legislative framework.
1.1 TERMS OF REFERENCE AND STUDY AREA
1.1.1 TERMS OF REFERENCE As provided by CSMC, the aims of this study are to: i. provide an up-to-date description of the state of groundwater contamination in the Cockburn Sound catchment, of the pressures on the resource base, and of the current management response; ii. identify the gaps in the current management response and indicate management strategies to address these gaps; and iii. outline a research and investigation program to improve the information and knowledge base for future decision-making. These aims provide a clear reference for the conduct of the study. However, the diversity of urban and industrial activities in the catchment makes impossible the task of compiling a fully detailed description of groundwater contamination in the Cockburn Sound catchment with the resources available to this study. In discussions with the CSMC Groundwater Quality Project Team, it was recognized that there were likely to be instances of groundwater contamination within the catchment that were unlikely to present direct threats to seawater quality in the Sound for the foreseeable future. It was agreed that whilst such contaminations would be noted, the prime focus of this study is to identify any major risks to seawater quality arising from the groundwater pathway into the Sound.
3
Stormwater drainage represents another pathway by which contaminated fluids may enter Cockburn Sound. In the main, stormwaters are discharged to the Sound via a network of drains, conduits and pipes, but the stormwater drainage system also includes compensation and infiltration basins (infiltrating to groundwater), and temporary buffered storage in wetlands and lakes. This report will briefly consider aspects of risk presented by those stormwaters that reach the groundwater system, and the management of the risks for the benefit of Cockburn Sound.
Another agreement was that the study would attempt to assess and rank the threats of the identified contaminations according to a risk weighting methodology. This was seen to depend on the prevalence and potential impact of the chemicals of concern – including their spatial density and volume of use through the catchment, the proximity of their use or spillage to the Sound and the local hydrogeological context. The physico-chemical properties of the chemicals and groundwater conditions will dictate their persistence and behaviour. Also of consideration was the type of potential impact on the marine environment – whether toxic or causing ecological disturbance. Lastly, if management was in place this would lead to mitigated or attenuated affects – so implemented or planned management and the potential for success of that management were also considered.
1.1.2 STUDY AREA The study is confined to the area outlined on Figure 1.2, referred to as the “Cockburn Sound catchment” for the present purposes. The outline essentially follows local government boundaries and is not necessarily congruent with the true hydrological catchment boundary for the Cockburn Sound area.
The catchment is bounded in the north by Woodman Point, in the west by Garden Island, and in the south by the Garden Island Causeway and extending east to Lake Coolongup. The eastern inland boundary is set by the Kwinana Freeway. The catchment thus includes parts of lands under the local government jurisdictions of Kwinana Town Council, Rockingham City Council and Cockburn City Council. Other government landowners are represented in the catchment, including Department of Defence and LandCorp. There are also extensive (and growing) areas of urban and residential development. Private industry has a significant presence in the catchment through heavy and light industry, vegetable production and commercial activities. Figure 1.3 provides a detailed locality map of the catchment, showing a range of land uses and planning initiatives typical of a busy growing urban and industrial catchment. Figure 1.4 shows a number of coastal developments planned or proposed for Cockburn Sound, including several major port and harbour expansions. Section 3.1.4 gives more details on these plans and proposals.
The CSMC boundary has since been extended to the north to include Owen Anchorage and the sea area as far west as Stragglers Rocks (see dashed boundary extension in Figure 1.4). For the purposes of this study, however, the earlier boundary definition is used (solid boundary in Figure 1.2), although the western boundary is extended to the approximate longitudinal centre line of Garden Island. It would be appropriate to perform a similar groundwater contamination study for the new catchment area.
4 Status of Groundwater Quality in the Cockburn Sound Catchment
Figure 1.2: Cockburn Sound Management Council boundary (black line). For the purposes of this Study, the boundary is enlarged to encompass the eastward draining catchments of Garden Island. Green lines indicate local government boundaries; red lines indicate major roads. Image supplied by Cockburn Sound Management Council.
5
Figure 1.3: Locality map and strategic developments planned for the South-West Metropolitan Sector. Data supplied by WA Department of Planning and Infrastructure, see WAPC [2005]. See facing page for information on map symbols.
6 Status of Groundwater Quality in the Cockburn Sound Catchment
Key to Symbols on Figure 1.3
Significant Water Upgrades (taps with numbered blue circles) 1 = Woodman Point Wastewater Treatment Plant 2 = Jandakot South Branch Drain 3 = Thomson’s Lake Branch Sewer 4 = Desalination Plant 5 = Kwinana Water Reclamation Plant
New and Improved Education Facilities (mortarboards with numbered pink circles) 1 = Coolbellup, North Lake, Koorilla primary schools amalgamation 2 = Warnbro community high school upgrade 3 = Kwinana senior high school redevelopment 4 = Settlers Hills primary school 5 = Secret Harbour middle school (not shown) 6 = Challenger TAFE marine training centre
Major Infrastructure Developments (“$” with numbered black circles) 1 = Marine Industry Technology Park 2 = Kwinana Fire Station
Western Power Projects (lightning icons with numbered yellow circles) 1 = Bibra Lake substation 2 = Waikiki substation 3 = Golden Bay substation (not shown) 4 = Glen Iris substation
New Railway Stations (“H” with numbered purple circles) 1 = Cockburn Central 2 = Kwinana 3 = Wellard 4 = Rockingham 5 = Warnbro
7
Figure 1.4: Coastal developments planned for Cockburn Sound, together with the new extension of the CSMC boundary in Owen Anchorage. Data supplied by WA Department of Environment.
8 Status of Groundwater Quality in the Cockburn Sound Catchment
1.2 STRUCTURE OF THIS REPORT Appreciating the complexities associated with the management and remediation of groundwater contamination in urbanized catchments demands considerable background in diverse areas of environmental science. Accordingly, this report summarizes a range of relevant background information and key publications pertinent to the Cockburn Sound catchment in subject areas including hydrogeology, climate, contamination chemistry and land use. This summary sets the scene for the following sections on the extant regulatory and management frameworks for activities surrounding the Sound, and on the known sources of groundwater contamination in the catchment.
The final section of the report presents a discussion of the means by which knowledge on the state of groundwater contamination in the catchment may be improved over time, and by which the impact of groundwater contamination on the environmental values of Cockburn Sound may be reduced over time to levels acceptable to the community. The main premise here is that improving the knowledge base on groundwater contamination in the catchment has the consequent effect of highlighting gaps in environmental practice or in scientific understanding and, hence, informing future management responses to the changing state of the environment.
2 State of Groundwater in Cockburn Sound Catchment
We commence the report by summarising the state of the Cockburn Sound catchment and how human inhabitants have interacted with the landscape. Because of the groundwater motivation for this study, the main elaboration of the overview is made in terms of hydrogeology and groundwater quality issues. Discussion of surface water processes, including drainage through the lakes and wetlands of the area, is largely neglected as these are not thought to provide intrinsic sources of groundwater contamination, except perhaps through episodic infiltration of stormwater or precipitation run-off that is buffered through some wetlands.
2.1 HYDROGEOLOGY OF COCKBURN SOUND
2.1.1 REGIONAL SETTING The Perth Basin is a geological deposit of marine and continental sediments up to twelve kilometres deep that extends east-west from the Darling Fault to many kilometres offshore from Perth’s coastline. The basin’s sediment layers extend from the surface (see Figure 2.1) to a depth of around two thousand metres below the present land surface, and contain mainly Jurassic age (210-140 million years old) and Cretaceous age (140-65 million years old) deposits. Above the Cretaceous formations, whose distribution is mapped in Figure 2.3, is a relatively thin layer of recent Tertiary to Quaternary age (less than 65 million years old) sediments that are known collectively as the superficial formations (Figure 2.1 and Figure 2.4). These vary in total thickness up to a maximum of approximately one hundred metres. Schematic cross sections through the mainland and Garden Island to a depth of around two hundred metres below sea level are depicted in Figure 2.4.
9
Figure 2.1: Surface expression of the superficial geological formations. Data supplied by WA Department of Industry and Resources.
10 Status of Groundwater Quality in the Cockburn Sound Catchment
Figure 2.2: Superficial groundwater flow areas. Isopotentials are contoured at 1 m intervals. Cross sections A, B and C are relevant to Figure 2.4. Data supplied by WA Department of Environment.
11 Figure 2.3: Subcrop geological formations underlying the superficial formations. Data supplied by WA Department of Environment.
12 Status of Groundwater Quality in the Cockburn Sound Catchment
Figure 2.4: Hydrogeological cross sections through Cockburn Sound and Garden Island; section lines are indicated on Figure 2.2.
13 Inshore from the coast, rain water that infiltrates into the superficial formations is stored as groundwater within the spaces between sediment grains. The saturated extent of the superficial formations is known as the Superficial Aquifer, from which approximately sixty percent of Perth’s total water demand is supplied. The Superficial Aquifer is also a major source of water for irrigation and industry. Replenishment of groundwater in the Superficial Aquifer occurs through infiltration of rainfall through sandy, well-drained soils. A small amount of this water leaks further down into the underlying Cretaceous and Jurassic age sediments, where it replenishes the confined aquifer system. The remaining un-utilised portion of superficial groundwater drains laterally through the Superficial Aquifer and discharges eventually to the ocean, estuary and rivers. This continuous process of diffuse replenishment and lateral drainage forms a number of distinct groundwater flow systems that can be recognised as regional groundwater mounds (Figure 2.2).
The Cockburn Sound study area overlies the southwest part of the Jandakot Mound and northern part of the Safety Bay Mound. The saturated thickness of the superficial formations is approximately twenty-five to thirty metres throughout this area. In the southern part of Cockburn Sound, the superficial formations are underlain by the Rockingham Sand. This deposit fills an eroded channel in the Cretaceous sediments that is known to be more than one hundred metres deep in places.
2.1.2 SUPERFICIAL FORMATIONS A number of distinct sediment layers compose the superficial formations in the Cockburn Sound area (Figure 2.1). Their stratigraphic sequence is illustrated schematically in Figure 2.5. The following hydrogeological descriptions of these units are based mainly on the synthesis by Davidson [1995].
2.1.2.1 TAMALA LIMESTONE Tamala Limestone (Figure 2.6) is a calcareous (contains greater than fifty percent calcium carbonate) deposit of former dune sand that unconformably overlies Cretaceous sediment and Rockingham Sand, i.e. the Tamala Limestone does not follow the underlying sediment in immediate age sequence, probably caused by a change in the depositional environment in the past. It contains various proportions of quartz sand, fine- grained to medium-grained shell fragments and minor clay lenses. The limestone typically exhibits secondary porosity in the form of numerous solution channels and cavities that are highly conductive to groundwater flow (Figure 2.7).
Garden Island is an offshore outcrop of Tamala Limestone and part of the Garden Island Ridge, which runs northwest through Point Peron, Garden Island, Carnac Island and Rottnest Island [Seale et al., 1988]. A roughly parallel sand and limestone ridge, called the Spearwood Ridge, is located onshore from the coast along the contact between the Tamala Limestone and Safety Bay Sand. The low area between these ridges is known as the Warnbro-Cockburn Depression, wherein Tamala Limestone outcrops as submarine reef.
Passmore [1970, Figure 37] depicted a cross section through the Tamala Limestone and overlying sediments that extended across Cockburn Sound from the southern end of Garden Island to the mainland. The section was taken along a similar line to Section C in this report and was based on drilling logs from Fremantle Port Authority Line 1 No 7 (FPA7), Line 10 No A (FPA10A) and No F1 (FPAF1). The base of the Tamala Limestone occurs at a depth of approximately twenty-five to thirty metres below mean sea level at these locations, consistent with drilling logs from the mainland.
14 Status of Groundwater Quality in the Cockburn Sound Catchment
2.1.2.2 ASCOT FORMATION The Ascot Formation is a shallow marine deposit that lies unconformably on Cretaceous sediments. It is characterised by grey to fawn, hard and friable calcarenite (consolidated sedimentary rock composed of sand-size particles and containing greater than fifty percent carbonate), which contains thin beds of fine to coarse sand. Bivalves and gastropods are common. Thick beds of shelly, silty clay can occur at the base of the formation.
2.1.2.3 GNANGARA SAND Gnangara Sand is pale-grey with fine to very coarse texture. It is overlain conformably by Bassendean Sand and unconformably by Tamala Limestone along its western margin. It unconformably overlies the Ascot Formation.
2.1.2.4 BASSENDEAN SAND Bassendean Sand is pale-grey to white and mostly medium textured. It contains traces of black, fine-grained heavy minerals. ‘Coffee rock’ commonly occurs near the water table as a layer of friable, limonite-cemented sand. Limonite is a dark-brown to black hydrated iron oxide. Bassendean Sand conformably overlies Gnangara Sand and unconformably overlies Tamala Limestone. At ground surface, Bassendean Sand is evident as the Bassendean dune system.
2.1.2.5 COOLOONGUP SAND Cooloongup Sand consists of fine-grained to coarse-grained quartz sand of grey and yellow-brown colour, with variable amounts of shell material (up to twenty-five percent). Where it is present, this unit unconformably overlies Tamala Limestone.
2.1.2.6 BECHER SAND Becher Sand originated in the near-shore marine environment and consists of grey, fine- grained to medium-grained quartz and skeletal sand that is mostly unstructured and bioturbated, i.e. the sedimentary bedding structure has been disturbed by biological activity. It unconformably overlies Tamala Limestone and is overlain by Safety Bay Sand. Becher Sand occurs along the coastal margin of Cockburn Sound and is typically ten to fifteen metres thick. The base of the unit can locally contain a layer of silty calcareous clay that is rich in shell fragments, and which acts as a confining layer to groundwater in Tamala Limestone. This layer is commonly referred to as “basal clay” or “shell bed” in drilling logs and is typically around one metre thick.
2.1.2.7 SAFETY BAY SAND Safety Bay Sand is a surface layer of the superficial formations that overlies Tamala Limestone and Becher Sand. It consists of cream, unconsolidated, fine-grained to medium-grained quartz sand and shell fragments. Traces of fine-grained, black heavy minerals are also present. Safety Bay Sand is clearly visible along Perth’s coastline as white sand dunes (Figure 2.8) that are re-worked offshore as submarine banks.
2.1.3 UNDERLYING (SUBCROP) FORMATIONS The superficial formations mostly overlie Cretaceous sediments that include the Kardinya Shale Member of the Osborne Formation and the Pinjar and Wanneroo Members of the Leederville Formation (Figure 2.3). A different situation exists in the southern part of Cockburn Sound where the Rockingham Sand underlies the superficial formations.
15
Safety Bay Sand (24) Bassendean Sand (80) Becher Sand (20) Basal clay Gnangara Sand (30) Tamala Limestone (110) Ascot Formation (25)
Rockingham Sand (110)
Cretaceous Sediments
SOURCE: This figure is based on information from Davidson [1995]
Figure 2.5: Stratigraphic sequence of superficial formations; numbers in parentheses indicate maximum thickness of units.
Figure 2.6: Tamala Limestone exposed (above the water table) in a limestone quarry.
16 Status of Groundwater Quality in the Cockburn Sound Catchment
Figure 2.7: Groundwater from Tamala Limestone discharging at high rate from solution channels into a dewatered excavation.
Figure 2.8: Safety Bay Sand at the shoreline of Cockburn Sound near Northern Harbour.
17 2.1.3.1 KARDINYA SHALE MEMBER Kardinya Shale consists of moderately to tightly consolidated, interbedded siltstones and shales, which are typically dark green to black, and includes thin beds of mostly fine- grained sandstone. It is a relatively poor transmitter of groundwater and is considered to be a competent aquitard (barrier to groundwater flow) that separates the Superficial Aquifer from the deeper Leederville Aquifer. Downward leakage of superficial groundwater through the Kardinya Shale Member is thought to be negligible compared to horizontal flow through the aquifer.
2.1.3.2 PINJAR AND WANNEROO MEMBERS The Pinjar and Wanneroo Members are upper units within the Leederville Aquifer and consist of discontinuous, interbedded sandstones, siltstones and shale of marine and non-marine origin. The subcrop of these two units beneath the superficial formations represents an area of direct contact between the superficial and Leederville Aquifers. The vertical direction of groundwater flow between the aquifers can be upward or downward dependent on the hydraulic gradient between them. Superficial groundwater can flow downward to replenish the Leederville Aquifer, or groundwater from the confined aquifer system can flow upward to replenish the Superficial Aquifer. In both cases, discharge from one aquifer constitutes recharge to the other.
2.1.3.3 ROCKINGHAM SAND Rockingham Sand occupies a deep channel incised into the upper surface of Cretaceous sediments. The unit consists of slightly silty, medium-grained to coarse-grained sand of shallow marine origin. The maximum thickness of Rockingham Sand is greater than one- hundred metres at the southern end of Cockburn Sound in the Rockingham area.
2.1.4 SUPERFICIAL AQUIFER Groundwater in the Superficial Aquifer flows generally in a westerly direction within the study area and discharges to the near shore marine environment along the coastline of Cockburn Sound (Figure 2.2). There are virtually no natural surface drains to the ocean because the coastal sands are permeable enough to prevent significant surface runoff. Table 2.1 presents hydraulic property data for the superficial formations.
The coastal strip of the Superficial Aquifer is characterised by large hydraulic conductivity. Values in the range 20 to 1 000 m d-1 are normally associated with coarse sediments such as coarse sand and gravel that are relative free of silt, clay and finer- grained sands that resist groundwater flow [Bouwer, 1978]. Inshore from Cockburn Sound, large values of hydraulic conductivity are related to solution features and subterranean channels in Tamala Limestone that can transmit large volumes of groundwater, rather than to the presence of coarse sediments. The values of hydraulic conductivity estimated from pumping tests in the limestone tend to be relatively large and contain significant and expected variability due to variation in local structure of the limestone. Such large values of hydraulic conductivity lead to relatively flat groundwater tables because a smaller hydraulic gradient is required to transmit an equivalent volume of groundwater. This relationship is reflected by small horizontal hydraulic gradients within the coastal strip of the study area that correspond to the extent and distribution of Tamala Limestone.
A relatively narrow band of sediments with lower hydraulic conductivity runs roughly parallel to the coastline along the contact between the Bassendean Sand and Tamala Limestone several kilometres inland from the coast (Figure 2.1). Nield [1999] attributed these steep gradients to the presence of clay in the Tamala Limestone, as indicated in hydrogeological logs from a dense network of monitoring bores in the vicinity of Alcoa’s residue disposal areas. A dramatic change in hydraulic gradient along this zone (Figure 2.2) is the main evidence for the existence of the apparent flow barrier. East Beeliar
18 Status of Groundwater Quality in the Cockburn Sound Catchment
Wetlands, a north-south chain of lakes and wetlands located approximately five kilometres from the coast, are surface expressions of elevated groundwater levels behind this barrier. Water levels in the lake system are up to eighteen metres above mean sea level.
Horizontal hydraulic gradients in the coastal strip are as small as 0.02% (equivalent to a one metre change in water table elevation over a five kilometre horizontal distance) and are larger than 1% across some parts of the flow barrier. This fifty-fold variation in hydraulic gradient indicates the same order of magnitude variation in aquifer hydraulic conductivity.
Along the coastal margin of the superficial formations, groundwater in Tamala Limestone is locally confined where the shelly clay layer at the base of the Becher Sand is present. Vertical hydraulic head differences between Tamala Limestone and Safety Bay Sand and observed propagation of tidal fluctuations hundreds of metres into Tamala Limestone provide indirect evidence that groundwater in the limestone is confined or semi-confined at these locations. In comparison, tide induced water table fluctuations in Safety Bay Sand and Becher Sand are rapidly attenuated inshore from the coast [Davis et al., 1994] because these sediments are less conductive and groundwater is unconfined.
Spatial variability in groundwater replenishment and aquifer hydraulic properties control the flow pathways and travel times for groundwater to move from source areas inshore from Cockburn Sound to the ocean. The presence of preferred flow paths within the sediments means that some areas of the Superficial Aquifer are likely to contain active, fast moving groundwater while other areas will contain relatively inactive, slow moving groundwater. Contaminants that are mobilized into relatively inactive areas of the flow system are likely to take longer to reach Cockburn Sound and will be retained in the aquifer for longer periods. The reverse also applies.
2.1.4.1 INFLUENCE OF SEA LEVEL VARIATION ON GROUNDWATER LEVELS Due to the presence of sediments with large hydraulic conductivity along the coastal margin of the superficial formations, shallow groundwater levels can be strongly influenced by changes in sea level at daily (tidal), seasonal and inter-annual time scales. Long-period sea level changes induce groundwater table variation further from the coast and affect a larger part of the groundwater system compared to short-period sea level change.
Nield (in PPK [2000]) compared monthly average sea levels to groundwater levels approximately two hundred metres inshore from the coast at Northern Harbour. The data depicts a strong correlation between sea level and groundwater level at monthly, annual and interannual time scales during the twelve year period from 1987 to 1999.
Walker [1994] investigated aquifer tidal propagation beneath the BP Refinery using five pairs of monitoring bores, and measured diurnal tidal fluctuations in groundwater levels of approximately two centimetres at a distance greater than 1.2 kilometres from the coast. These observations were consistent with the presence of Tamala Limestone confined by overlying basal clay.
Smith and Hick [2001] measured tide induced diurnal fluctuations in superficial groundwater levels that were approximately 15% tidally efficient at a distance of around one-hundred and eighty metres from the coast. Since the basal clay was not present at this location, these results indicated the presence of highly conductive coastal sediments; most likely Tamala Limestone.
19
Data Source Property and Value Location and Method Bodard [1991] T = 190 - 235 Safety Bay Sand K = 10 - 30 S = 0.3 (unconfined) B = 10 Bodard [1991] T = 1 700 - 2,600 Tamala Limestone K = 100 - 250 n = 0.3 S = 0.3 ± 1.5 (unconfined) S = 0.02 (confined) B = 10 Walker [1994] K = 100 - 250 (aquifer unspecified) BP Refinery, slug testing of 20 bores Davidson [1995] K = 6 - 50 Cockburn Sound area, Superficial Aquifer Nield [1999] T = 40 000 (superficial) Alcoa Kwinana Refinery; pump test Nield [1999] K = 400 - 1,660 (low recharge) Cockburn Sound coastal strip; Cockburn Groundwater Area model K = 800 – 3 000 (high recharge) calibration, Superficial Aquifer PPK [2000] T = 13 000 (JBTB1 early-time data) Inshore from Northern Harbour; constant rate pump tests on bores T = 9 400 (JBTB1 late-time data) JBTB1 and JBTB2 (observation T = 19 900 (JBMB9S recovery) bores JBMB9S, JBMB9D, WPM5C, JBMB1), Superficial Aquifer T = 23 800 (JBMB9S early-time data) S = 2.0E-06 (as above) T = 54 200 (JBMB9D early-time data) S = 1.4E-01(as above) T = 9 000 (JBTB2 early-time data) T = 28 800 (WPM5C early-time data) S = 9.0E-02 (as above) T = 39 700 (JBMB1early-time data) S = 1.0E-01(as above) T = 25 000 (adopted mean value) S = 1.0E-01(adopted mean value) Nield in PPK [2000] K = 900 (superficial) Northern Harbour; groundwater model calibration Smith and Hick [2001] K = 53 - 174 (Safety Bay Sand) Northern Harbour, tidal method Trefry and Bekele [2004] T/S = 60 000 (Superficial Aquifer) Garden Island, tidal method T/S = 30 000 (western superficial) T/S = 100 000 (eastern superficial) K = 5-10 (Superficial Aquifer)
Ksand:Klimestone = 1:50
Table 2.1: Estimated hydraulic properties of the Superficial Aquifer. Symbols and dimensions: n, porosity [-]; K, saturated hydraulic conductivity [m.d-1]; B, aquifer saturated thickness [m]; T = kB, aquifer transmissivity [m2.d-1]; S, aquifer storage coefficient [-].
20 Status of Groundwater Quality in the Cockburn Sound Catchment
Figure 2.9: Estimated saline wedge thickness distribution. Groundwater isopotentials are contoured at 1 m intervals. Isopotential and conservation category data supplied by WA Department of Environment.
21
Trefry and Bekele [2004] analysed measurements of diurnal fluctuations in groundwater levels along a transect across Garden Island. Tidal efficiencies were large in the Superficial Aquifer, and indicated that the surface topography of the Tamala Limestone consists of strong peaks and troughs. Furthermore, the analysis indicated that the limestone was significantly more transmissive than the overlying Safety Bay Sand (see Table 2.1), especially at larger spatial averaging scales.
2.1.4.2 SEAWATER INTRUSION WITHIN THE SUPERFICIAL AQUIFER The salt wedge within the superficial formations adjacent to Cockburn Sound is known to extend up to two kilometres inshore. Due to the large hydraulic conductivity of Tamala Limestone and the small inshore hydraulic gradients, the salt wedge is expressed as a long, flat tongue of saltwater that is commonly observed as a layer of saline water at the base of the superficial formations. Where the Tamala Limestone is confined above by basal clay that extends to the coast, a second and much smaller salt wedge is present in the sand units overlying the clay. Only a few bores in the Cockburn Sound study area intersect the salt wedge and enable direct observation of saltwater intrusion. Unless a bore is installed specifically for this purpose, it is normally undesirable to drill into or below the saltwater-freshwater interface.
Where the depth of the saltwater-freshwater interface adjacent to Cockburn Sound is known, the interface position is reasonably well predicted by the Ghyben-Herzberg approximation. This is a hydrostatic relation that is based on the density difference between freshwater and seawater. It predicts that, in a freshwater aquifer, the depth to an abrupt saltwater-freshwater interface will be approximately forty times the height of the groundwater table above mean sea level. Figure 2.9 depicts the theoretical extent and thickness of the coastal salt wedge calculated by Smith et al. [2005]. For this purpose, the base of the Rockingham Sand was used to represent the base of the superficial formations where the Rockingham Sand was present.
Monitoring bores that are known to intercept the salt wedge in the study area are the Mayor Road multiport bores (MR4M to MR6M) and the Cockburn Saltwater Interface monitoring bores (CSI1/97, CSI2/97 and CSI3/97). The Mayor Road bores are located directly east and south of Lake Coogee adjacent to the northern end of Cockburn Sound. The saltwater interface in this area is estimated to be around twenty-three metres below mean sea level [Smith et al., 2003].
Cockburn Saltwater Interface monitoring bores CSI1/97 and CSI2/97 are located closer to the coast near Challenger Beach, approximately one-hundred and fifty metres from the ocean. Seawater intrusion is detectable at about nine metres below mean sea level in CSI2/97, which appears to be screened within the mixing zone. At approximately nineteen metres below mean sea level in CSI1/97 the aquifer appears to contain seawater only. Monitoring bore CSI3/97 is located further inshore, approximately three- hundred and fifty metres from the coast where the aquifer is apparently unaffected by saltwater intrusion at six metres below mean sea level.
Gerbaz [1999] monitored groundwater levels and the saltwater interface position beneath the BP Refinery in eleven monitoring bores. The salt wedge was intercepted in nine bores and the average depth below water table to the saltwater interface was around eighteen metres; however, the distances between the coast and the monitoring bores were not reported. The extent of saltwater intrusion beneath the refinery was probably affected by groundwater pumping from the refinery production bores and was observed to be greater in the middle of the refinery area than at the northern and southern boundaries. Reductions in local rainfall have also been correlated with inland movement of the saline wedge. Evidence from the Alcoa premises indicates inland migration of the wedge by
22 Status of Groundwater Quality in the Cockburn Sound Catchment
approximately 200 m over the last 16 years, at an increasing rate of movement. CSBP data also indicates some inland movement of the saline wedge.
2.1.5 ROCKINGHAM AQUIFER The Rockingham aquifer is defined in association with the Rockingham Sand and is locally confined by discontinuous clay lenses at the base of the superficial formations. Confinement of groundwater in the Rockingham aquifer is indicated by propagation of tide induced water table fluctuations more than one-hundred and fifty metres inland from the shoreline [Passmore, 1970]. This suggests either very high aquifer transmissivity — allowing high rates of tidal groundwater flow — or propagation of the tidal signal through elastic expansion and compression of the aquifer under confined or semi-confined conditions. Based on the sediment type, the latter explanation is more likely.
The ocean salt wedge can penetrate deeper into the Rockingham aquifer because the sediments are thicker and deeper than in the superficial formations. The bottom part of the Rockingham aquifer contains seawater to an elevation of around sixty-five metres below sea level, whereas the top forty metres contain groundwater of salinity less than 1,000 mg/L [Davidson, 1995]. Groundwater from the Safety Bay Mound discharges to the ocean over the top of the salt wedge in the local direction of the coast. The Rockingham aquifer is assumed to have similar hydraulic properties to the sands in the superficial formations.
2.1.6 CONFINED AQUIFER SYSTEM The confined aquifer system of the Perth Basin is a multi-layered system of aquifers and aquitards that is replenished by slow downward flow of groundwater from the overlying superficial formations. It extends tens of kilometres offshore beneath the seabed and is thought to discharge terrestrial groundwater to the ocean at least several kilometres from the coast, possibly through offshore geological faults [Davidson, 1995]. Nevertheless, the precise mechanism and locations for confined submarine groundwater discharge are unknown.
The major defined units in the confined aquifer system are the Leederville Aquifer, the uppermost aquifer underlying the Superficial Aquifer, and the Yarragadee Aquifer, which underlies the Leederville Aquifer. The Leederville Aquifer is separated from the Superficial Aquifer by the Osborne Formation; the Kardinya Shale is the dominant confining member of the Osborne Formation. The Yarragadee Aquifer is separated from the Leederville Aquifer by the South Perth Shale, at varying elevations approximately 200-800 m below ground.
Vertical exchange of groundwater between the Superficial Aquifer and confined aquifer system varies across the Perth region. Five to ten percent of groundwater recharge to the superficial formations was estimated to leak downward into confined aquifers [Davidson, 1995]. Over most of the Cockburn Sound study area, the Osborne Formation (Figure 2.3 and 2.4) is thought to be a competent aquitard that restricts vertical exchange of groundwater between the Superficial Aquifer and the Leederville Aquifer. Replenishment of the confined aquifer system is believed to occur mainly in other areas where the Osborne Formation is absent.
It is relevant to note that offshore in the central and southern parts of Cockburn Sound, the upper members of the Leederville Aquifer (Pinjar and Wanneroo Members) apparently subcrop directly beneath Tamala Limestone, which is only ten to fifteen metres thick. The average hydraulic head in the Leederville Aquifer at the coast was around five metres above the water table elevation of the Superficial aquifer [Davidson,
23 1995], indicating a potential for confined groundwater to discharge within Cockburn Sound.
2.1.7 GROUNDWATER TRAVEL TIMES Despite the complexity of the Superficial Aquifer system near Cockburn Sound, it is possible to estimate effective travel times for groundwaters moving between the inland edges of the catchment and the shore of the Sound. Smith and Johnston [2003] discuss groundwater flow simulations based on a catchment scale water balance model. The usual measure is the groundwater flow rate or seepage velocity, v, defined over a suitable length scale Δx by K Δh v = , (2.1) n Δx where K is the effective hydraulic conductivity of the aquifer over the length scale, n is the effective aquifer porosity and Δh/Δx is the hydraulic gradient. The choice of length scale is important – as a first approximation we consider the whole-of-catchment scale. Referring to Figure 2.9, we see that the hydraulic head along the eastern edge of the catchment area is approximately 20 m AHD, whilst the sea level is approximately 0 m AHD nearly 8 km to the west, hence Δh/Δx ≈ 20/8000 = 0.0025. Nearer the coast the gradient may be as small as 0.001. Assuming a porosity value of n = 0.3-0.4 (reasonable for sands and local limestones) and a representative hydraulic conductivity of K = 10-20 m/d yields v ≈ 10-60 m/year. At this rate, groundwater at the eastern margin of the catchment would take approximately 130-800 years to travel the eight kilometres to Cockburn Sound. For sources located 1 km from the Sound, the travel times would be 16-100 years. However, based on Table 2.1, there is evidence that the local hydraulic conductivities could be considerably larger than 20 m/d in some parts of the catchment. As a general rule of thumb, doubling the effective hydraulic conductivity would reduce the net travel time by half, e.g. using K = 40 m/d would bring the travel time back to approximately 8-50 years for a 1 km travel distance.
Using the whole-of-catchment scale tends to obscure local variations in groundwater flow velocities. Figure 2.9 shows that the local head gradients are far from uniform across the catchment. The groundwater levels in the Figure show that head gradients are steepest toward the eastern margin of the catchment (toward the Jandakot Mound) and are very flat along the coastal strip. Thus it is to be expected that velocities will be above the mean estimate at locations far inland in the catchment where the high-conductivity Tamala Limestone formation is less prevalent in the Superficial Aquifer. The situation is less clear closer to the coast. In the northern half of the shoreline, Tamala Limestone tends to outcrop at the ground surface, indicating that the Superficial Aquifer is dominated locally by limestone with potentially high (and spatially variable) hydraulic conductivities, and hence more rapid groundwater flows. However the measured hydraulic gradients are much lower than the mean estimate above; the local velocity, being the product of the high conductivity with the low gradient, is hard to measure or infer with reasonable confidence. There is potential that preferential pathways through the limestone may provide rapid short circuiting of the groundwater flow in this part of the catchment.
At James Point, or further south, the Superficial Aquifer contains a greater depth of Safety Bay Sands and is expected to present a more uniform spatial distribution of hydraulic conductivity, especially near the water table. The conductivity values are likely to be significantly lower than those areas dominated by limestone to the north. Even so, the observed hydraulic gradients are still very low, which means that velocities will also be low. In general terms, then, groundwater velocities at or near the water table are likely to be reasonably high near the Jandakot Mound, well inland from the coast. Velocities along the southern industrial strip may potentially be lower, whilst information at the north end of the Sound is insufficient to support an estimate. Overall, it is estimated that
24 Status of Groundwater Quality in the Cockburn Sound Catchment
groundwater transit times through the Superficial Aquifer from the Jandakot Mound to the shore of Cockburn Sound range from at least a few decades upwards.
2.2 FUNDAMENTALS OF GROUNDWATER CONTAMINATION
Large volumes of chemicals and water are used in the Cockburn Sound catchment. These are stored, processed, shipped, disposed and treated in a variety of ways throughout the catchment.
There are four main significant users of chemicals and water: • Industry • Corporations and semi-Government agencies such as the Water Corporation and Western Power • Population centres or residential areas • Agricultural activities
These and other land uses lead to impacts on groundwater in the catchment, which may eventually discharge to Cockburn Sound.
2.2.1 LAND USE IMPACTS ON GROUNDWATER QUALITY
In December 1994 the Select Committee on Metropolitan Development and Groundwater Supplies reported to the Legislative Assembly of Western Australia, see Carew Hopkins [1996] for a summary. The Committee was established because of the increasing conflict between land use and groundwater protection in Western Australia, and because development over or near important groundwater reserves was considered ad hoc. They detailed what they saw as the major threats to groundwater quality under a range of land uses – including Industrial and Commercial, Rural Grazing, Horticulture, Septic Tank Density, Special Rural Zones, and Urban – these are all land uses apparent in the Cockburn Sound catchment. Overall they noted that most land uses impacted groundwater beneath. It is worth noting that the most important issue raised by the Committee was the need to improve coordination in land planning and water protection.
Several investigations and reports have been produced for the Perth region on the impacts of land uses on groundwater quality: • for Urban impacts see for example McFarlane [1984], Whelan and Barrow [1984], Atwood and Barber [1988], Gerritse et al. [1990], Bawden [1991], Barber et al. [1994], Patterson et al. [1998, 2000] • for chronic releases in Urban areas see Appleyard [1995a], Davis and Appleyard [1996], Appleyard et al. [1997], Davis et al. [1999] • for horticultural impacts see, for example, Pionke et al. [1990] and Lantzke [1997] • for industrial impacts see the summary comments for each Industry in Section 4, and, for example, Davis et al. [1993] and Bastow et al. [2005] • for waste disposal impacts including landfills see, for example, Davis et al. [2005] • for the potential impacts of acid sulphate soils, see for example, DoE [2004b; 2004c]
25 In addition Hirschberg [1991] mapped known and inferred point sources of pollution of groundwater across the Perth basin.
2.2.1.1 POTENTIAL URBAN IMPACTS Based on historical data, Atwood and Barber [1989] and Barber et al. [1994] reported increases in nitrate over time due to increased urbanisation of the Gwelup area of Perth, and also increases in other inorganic compounds, and some organic contaminants. They, along with Gerritse et al. [1990] also noted the possibility of natural denitrification (transformation of nitrate to harmless nitrogen gas and water by micro-organisms) occurring in Bassendean Sand. The conditions required for denitrification were not observed to be present within the Spearwood Sand, which is the more common geomorphological unit found in the Cockburn Sound catchment, along with the Safety Bay Sand unit. Otto et al. [1999] reported on nitrate trends in groundwater from 204 bores in the Jandakot mound area. They found variable increases in concentrations from 1990 to 1997.
Gerritse et al. [1990] compared groundwater quality underneath several types of land use, including: • pine plantations on the Gnangara Mound • recently urbanised, sewered suburbs • largely undeveloped areas near Malaga at the time of the study • well established predominantly sewered residential areas • old, predominantly unsewered residential areas
They also surveyed the use of chemicals by households. They considered • all major cations and anions • minor trace ions such as ammonium, nitrate, nitrite, copper, zinc, lead, cadmium, • organic nitrogen and total organic carbon • hydrocarbons and solvents e.g., benzene, toluene, tetrachloroethene (PCE), trichloroethene (TCE) • pesticides such as organochlorins, e.g., lindane, dieldrin, DDT; and organophosphates e.g., chlorpyriphos • fluorescent whitening dyes (added to textiles, paper, plastics and soaps • total microbial counts and toxicity testing using the inhibition of bacterial luminescence
Major findings were that groundwater beneath all urban areas had increased ‘salt’ content, but that none exceeded guidelines at the time. This mainly consisted of increased concentrations of sulphate and chloride. From estimates of nitrogen used by households and the average recharge rate to groundwater, Gerritse et al. [1990] calculated the maximum concentrations of nitrate that may eventually be seen in groundwater under urban areas as 40 mg/L in sewered areas and 70 mg/L in unsewered areas. Measured concentrations in groundwater were much less than that (from non- detect to 18 mg/L), indicating significant denitrification, especially under Bassendean Sands, or continuing development of nitrate concentrations over time. No other significant concentrations of the chemicals of concern, as listed above, were observed in their study. However, they note that high concentrations are possible based on chemical use and recharge rates, and allude to the likelihood that concentrations may increase; the need to monitor groundwater quality was stressed.
Appleyard [1995b] compared groundwater quality under several sewered suburbs with those of an undeveloped area. He investigated (i) Nedlands, which had been urban and sewered for over 50 years; (ii) Whitfords and Ocean Reef, which had been urban and sewered for less than 20 years; and (iii) Barragoon, which was undeveloped at the time of the study. He found that groundwater in urban areas was younger due to enhanced
26 Status of Groundwater Quality in the Cockburn Sound Catchment
recharge under urban development; that nitrate concentrations were typically less than 0.5 mg/L in undeveloped areas and as high as 5 mg/L in urban areas; and that sulphate concentrations in groundwater increased with the age of the urban development from an average of 8 mg/L to 69 mg/L.
Patterson et al. [1998, 2000] reported a controlled tracer test whereby they applied pesticides and other organic contaminants to the ground surface at low rates typical of those likely to be applied by residences in Perth. They found that the only compound of note that had significant mobility through the unsaturated zone and that may leach to groundwater was atrazine.
2.2.1.2 POTENTIAL CHRONIC URBAN IMPACTS Here sites of chronic release are defined to be urban activities that may be localised and on-going, and possibly where chemical release may be focused and locally intense. These may be typically small scale premises or areas.
Examples of such activities and sources of chemical release may be service station sites, drycleaners, pest control operators and depots, and small scale commercial businesses that have a consistent throughput of chemicals. Septic tanks in unsewered areas could also be viewed similarly (see Whelan and Barrow [1984]).
Appleyard et al. [1997] investigated the practices of pest control operators and their impacts on groundwater in the Perth area. They found a range of pesticide concentrations in groundwater beneath washdown areas in excess of drinking water and ecological criteria. In particular they found dieldrin, long after its discontinued use. The most prevalent pesticide was diazinon, which is not normally considered to have a high mobility or potential to reach groundwater. This is in contrast to the findings of Patterson et al. [1998, 2000], who looked at low-level releases. In this case, the wash down waters used by the pesticide depot operators accelerated the penetration of otherwise retarded chemicals enabling them to reach the groundwater and move off-site (see also Appleyard [1995a]).
In these situations, high concentrations of hazardous compounds may be present in groundwater in the near vicinity of the site. Where flows are high and compounds are persistent, then longer and larger plumes in groundwater may occur. For example, the plume of pesticides in the Dianella area was over 300 m long but emanated from a local backyard sump (see Appleyard [1995a]). Similarly, dry cleaners sites in the US have generated significant impacts on groundwater of chlorinated solvents such as PCE. Again, these are very localised sources of potential impact.
Such small scale sources are less well identified and defined across our urban areas and, because of the localised nature of the contaminant plumes, individual monitoring boreholes may not detect impacts from such sources.
2.2.1.3 POTENTIAL HORTICULTURAL IMPACTS An intensive study of the potential impacts of horticulture on groundwater beneath Spearwood sands was undertaken by Sharma et al. [1989] and Pionke et al. [1990]. They instrumented sites with collection lysimeters below Chinese cabbage and cauliflower crops to collect leachate water and chemicals. They also monitored shallow and deep boreholes in the vicinity of the horticulture at Coogee and Gnangara to determine actual groundwater concentrations. The study was focused on nutrient impacts – nutrients were mostly applied to the crops as poultry manure, roughly about five times in excess of crop uptake for nitrogen and greater than ten times for phosphorus. They found nitrate concentrations as N of 9-80 mg/L in shallow groundwater, and 0.1-56 mg/L in deeper
27 groundwater wells. Orthophosphate concentrations reported as P in the root zone (or lysimeters) were highly variable averaging 0.1 mg/L but as high as 13.5 mg/L – there was less evidence of phosphorus impacts on groundwater probably due to the strong sorption of phosphorus to soil. This could lead to breakthrough of high concentration of phosphorus in the future from the mass stored in the soil profile due to sorption. In contrast Lantzke [1997], who studied horticulture at nine sites between 1992 and 1997 both on Bassendean Sands and Spearwood Sands, found up to 16 mg/L of phosphorus and 29 mg/L nitrate in boreholes on the edge of a turf farm on Bassendean Sands. Similar trends were found for the other sites studied on Bassendean Sands.
Pesticide use is also prevalent across the horticulture industry. Less direct testing seems to have been undertaken to assess the potential for pesticide leaching under horticulture on the Swan Coastal Plain soils. One exception is the study by Kookana et al. [1995] which showed that some pesticides (fenamiphos and metalaxyl) leached rapidly through a Karrakatta Sand profile at Medina. The results varied by pesticide type, a result thought to be influenced by variations in soil organic matter content and microbial population with depth [Di et al., 1998]. Extensive research on pesticide leaching has been carried out overseas.
Recently the horticultural industries in the catchment have begun adopting root zone control technologies, which have the potential to reduce the amount of water applied to crops and which may also reduce the rate of contaminant leaching to the underlying groundwater.
2.2.1.4 POTENTIAL INDUSTRY IMPACTS Industry import, generate and export a wide range of chemicals – nitrogen and phosphorus-rich chemicals for fertilisers, fuels and solvents, herbicides and pesticides, salts, ash materials, metals and metal-enriched wastes, etc. Often substantial volumes can be stored on site, and despite precautions significant loss can occur to the subsurface through direct leakage, spills, leaking sewer or drainage lines, infiltration from waste storages, tank corrosion and ruptures, and the like. Because of the longevity of tenure of heavy industry, complex piping and production networks, and their usually large areal footprints, local groundwater impacts can be severe. Most of the industry impacts are summarised in Section 4.
2.2.1.5 POTENTIAL LANDFILL IMPACTS In the past most landfills were unlined and, as such, leachate formed within the landfill would infiltrate through the underlying soil and recharge the groundwater. Typically, landfill leachate changes its composition over time, but is noted for its high ammonia, chloride, metals and organic carbon concentrations – see, for example Davis et al. [2005]. There are several landfill facilities in the Cockburn Sound catchment area, including Henderson Landfill, 9 Mile Quarry, AAA Bulk Haulage Landfill, Baldivis Landfill, and the decommissioned Ennis Road Landfill.
2.2.1.6 POTENTIAL ACID SULPHATE SOIL IMPACTS Disturbance of soils with high levels of sulphide minerals, such as those around low-lying or marshy areas, may lead to oxidation of the sulphides and generation of sulphate which gives rise to acidic leachate [DoE, 2004b]. This can also lead to the enhanced leaching of metals and metal plumes in groundwater. Such disturbance can occur due to drainage or pumping of groundwater leading to lowering of water table levels and exposure of sulphide-rich sediments to atmospheric oxygen. This can occur during re-development or in a drying climate cycle. Such instances potentially (and actually) occur across large areas the Swan Coastal Plain [DoE, 2004c]. In the Cockburn Sound area the incidence of potential acid sulphate soils appears limited, at least along the narrow coastal margin, apart perhaps from the wetland areas inland from Woodman Point in the north, to the
28 Status of Groundwater Quality in the Cockburn Sound Catchment
southeast of the CSMC management region, and on Point Peron in Rockingham [DoE, 2004c].
2.2.1.7 POTENTIAL STORMWATER IMPACTS Stormwater arises from surface runoff associated with rainfall or washing events, e.g. through rainfall or cleaning waters collected by paved surfaces (roads, car parks, industrial hardstands) and directed to the stormwater drainage system. The stormwater flows are typically episodic and can carry with them a diverse range of contaminants and detritus, including solvents, tars, metals, paints, pathogens, nutrients and rubbish. After long dry spells, the “first flush” stormwater can be notoriously noxious. The sheer volume of these stormwaters and their sudden appearance are problematic for the engineering of wastewater systems. Typically, overflows of the stormwater systems are directed to compensation basins and/or natural wetlands either for temporary storage or for direct infiltration to groundwater. DoE has issued a manual for the management of stormwater in WA [DoE, 2004]. In the Cockburn Sound catchment stormwater ultimately discharges directly to the Sound through a network of infrastructure drains. Stormwater quality is not routinely monitored across the Cockburn Sound catchment, although some data is available for stormwater and industrial drains from 2000-2001 [DoH, 2001]. DoH has identified that stormwater drains near the Southern Flats shellfish production areas may present potential risks to seawater quality and an active management plan is in place [DoH/DoF, 2005].
Lakes and wetlands are an integral part of the stormwater and runoff management plan for the catchment. Lakes Coogee and Richmond are major receptors of stormwater and runoff in the catchment, and both discharge directly to Cockburn Sound through artificial drains. Lake Coogee discharges to a drain entering the Sound near Woodman Point, and Lake Richmond discharges to a drain (see Figure 2.10) entering at Mangles Bay (see CSMC [2002]). Further west, Rotary Park discharges to Palm Beach. The Southern Metropolitan Drainage Scheme also has a pipe outfall to Cockburn Sound from the Beeliar Wetlands System. The Spectacles wetlands north of Kwinana forms part of the Peel Main Drain system, draining stormwater and runoff from the north and east of Cockburn Sound catchment to the Peel-Harvey estuary. The Peel Main Drain was classed as eutrophic because of the elevated nutrient concentration of its waters [Khan and Zubair, 2001]. In terms of direct impact to groundwater quality, stormwater is most likely to enter the groundwater through leaking compensation basins or through infiltration basins and wetlands. In a study of three Perth infiltration basins, Appleyard [1993] showed that there was potential for accumulation of metals in basin sediments, but evidence for other significant contamination was weak. Interestingly, stormwater infiltration was associated with increased dissolved oxygen levels, indicated by iron encrustation on nearby sampling bores. Detailed studies of stormwater impacts on groundwater quality beneath receiving wetlands are lacking in the Cockburn Sound context. This is a science gap: the practice of diverting untreated stormwater to significant wetlands seems to be at odds with an environmental quality focus. However the effects of this practice upon the groundwater quality are unclear and no assessment can yet be made of any related impacts to seawater quality in Cockburn Sound.
2.2.2 CLASSES OF CONTAMINANTS AND THEIR PROPERTIES
Based on the possible land use impacts described above and other considerations, the following broad classes of contaminants are of interest: • Nutrients (e.g. from horticulture, urbanization, industry) • Metals and acids (e.g., from acid sulphate soils, mineral processing) • Petroleum hydrocarbons (e.g., from heavy and light industries, and fuel storages) • Chlorinated or other halogenated hydrocarbons (e.g., solvents from industry) • Pesticides and herbicides (e.g., from road and rail reserves, horticulture)
29 • Other organic compounds (e.g., PCBs from power generation) • Other inorganic compounds (e.g., salt mobilization from land use changes) • Pathogens and pharmaceuticals (e.g., from livestock, sewage, biotech)
2.2.2.1 NUTRIENTS Nitrate is a common chemical across many different land uses. It is a source of nitrogen, and in excess in marine water bodies can lead to algal growth and impacts on seagrass. Nitrate is not readily retarded/adsorbed in the sand or limestone aquifers of Cockburn Sound. It will readily denitrify if there is an excess of organic carbon in the aquifer, which is unlikely except where there are additional anthropogenic sources – such as with septic tanks. Nitrate can be formed from ammonia via microbial oxidation on contact with air. This may occur in the soil profile above groundwater, which in the Perth area is often aerated to some depth (see Barber et al. [1990]). When formed and when present in groundwater, nitrate can therefore be preserved and can be mobile. It is not deemed to be a toxicant but a nutrient source that poses a potential ‘disturbance’ hazard for the Cockburn Sound ecology.
Ammonia is considered a toxicant in marine waters (see ANZECC & ARMCANZ [2000]) and also acts as a nutrient that may stimulate algal growth and can contribute toward eutrophication. It would not be readily retarded/adsorbed in the sand or limestone aquifers of Cockburn Sound. It will oxidise to form nitrite or nitrate, where oxygen is present, such as in the soil profile above the water table. Ammonia can also be formed from nitrate via ammonification, but this is less common. Ammonia dissolves in water to produce the ammonium ion.
Phosphorus is an ecological hazard as it is a nutrient that can stimulate algal growth, and is often limiting in marine environments. It is sourced from septic effluent, garden fertilisers, waste effluents and the manufacture of fertilisers and other goods. Phosphorus will adsorb readily onto some mineral phases in soils – and consequently is heavily retarded in some soil types.
2.2.2.2 METALS AND ACIDS Most metals are not readily mobile in groundwater where pH values are buffered. Along the coastal margin of Cockburn Sound this is largely the case due to the calcareous nature of the sand and limestone aquifers. Exceptions may be arsenic which can be mobile under changeable pH conditions. Acid sulphate soils, which are most often associated with low lying marshy landscapes, can be disturbed if drained or redeveloped, and then can release acids and metals into solution [see DoE, 2004b]. Metals and acidity can then be persistent.
2.2.2.3 PETROLEUM HYDROCARBONS Petroleum hydrocarbons are ubiquitous across most industries, Government agencies and communities. In Cockburn Sound the BP Refinery is located on the foreshore at James Point. In early studies of underground storage tanks – common across Perth – 20% were observed to show signs of leakage (see Barber et al. [1991]). Petroleum fuels are complex mixtures of many compounds with a wide range of physico-chemical properties and mobilities. For example, benzene is not very sorptive and is sparingly soluble but naphthalene, which is a polynuclear aromatic hydrocarbon (or PAH), is much more sorptive and much less soluble. Some of the compounds are deemed carcinogenic, whilst others are not. As indicated in Section 2.3.3.6 below, petroleum hydrocarbons can naturally biodegrade in groundwater if electron acceptors such as oxygen, nitrate, iron oxides, sulphate or carbon dioxide are present in groundwater. If these electron acceptors are absent then petroleum hydrocarbons may persist in groundwater.
30 Status of Groundwater Quality in the Cockburn Sound Catchment
Figure 2.10: The Lake Richmond Drain. CSIRO photo taken November 2005.
31 2.2.2.4 CHLORINATED HYDROCARBONS Chlorinated hydrocarbons (e.g., trichloroethene or TCE) are often used as solvents in paints and other products and as degreasers for heavy machinery or metal parts. They are also used by drycleaners, to clean gas streams and as source materials for the manufacture of plastics. They have been widely used and small volumes can have significant impacts on water quality [Benker et al., 1996; Davis and Appleyard, 1996]. Benker et al. [1997] showed that TCE can be very mobile with little retardation or biodegradation in aquifers with low levels of natural organic carbon. Biodegradation of PCE and TCE is possible where excess carbon is present to create anaerobic conditions (conditions under which all oxygen is used up in the aquifer). Some lightly chlorinated compounds such as vinyl chloride may also naturally biodegrade under aerobic conditions.
2.2.2.5 PESTICIDES AND HERBICIDES Pesticides and herbicides are used on parklands, by horticulture and agriculture, and by householders. They are manufactured within the catchment and would have been disposed of to waste landfill facilities in the area. As indicated earlier, many of these compounds strongly sorb, or biodegrade. It is generally recognised that the most mobile of these compounds is atrazine – a broad-leaf herbicide used to keep weeds under control. Atrazine will degrade aerobically [Franzmann et al., 2000]. Additionally, a significant plume of chlorophenols and phenol herbicides is present in the catchment [Bastow et al., 2005].
2.2.2.6 ENDOCRINE DISPRUPTORS There is increasing concern and investigation worldwide as to the occurrence and persistence of endocrine disruptors in the environment, and especially in water bodies. Endocrine disruptors are a large class of compounds including pesticides. Hormone steroids and specific surfactants used in domestic and industrial situations and their metabolites are thought to disrupt endocrine function in wildlife and humans. Ying et al. [2002a, b] reviewed the fate of these compounds. Hormone steroids are excreted by humans and animals. Natural estrogenic steroids have solubilities of 0.3-13 mg/L in water, adsorb moderately to soils, and are reported to degrade rapidly in soil and water environments [Ying et al., 2002a]. Effluents from waste water treatment have typically had concentrations below 0.1 μg/L. One of the hormone steroids was found at a concentration of 6-66 nanograms per litre in groundwater impacted by poultry and cattle manure waste. Metabolites of some surfactants (alkylphenol ethoxylates or APEs) can also mimic natural hormones [Ying et al., 2002b]. APEs appear to be retarded onto soils and sediments, and degrade in water – fastest under aerobic conditions. Aerobic (oxygenated) conditions do not always occur in groundwater environments.
2.2.2.7 PATHOGENS Pathogens are organisms which, under appropriate conditions, cause disease in plants, animals or humans. Pathogens include bacteria and viruses. Pathogens may enter the groundwater system through effluent discharges or normal sanitary disposal. The use of septic tanks in urban and industrial areas is a prime vector for pathogen contamination of groundwater, especially contamination by faecal bacteria, as well as by nutrients. The Cockburn Sound catchment has been exposed to significant use of septic tanks over the past five decades or more. For example, the Hope Valley town site and the industrial strip are unsewered and have relied upon septic tank systems for sewage disposal. Parts of Kwinana and Rockingham are also either unsewered or have recently been converted from septic tank disposals. The longevity of pathogens within aquifers depends on the local soil type and hydrochemical environment.
The potential for impact of pathogens on water quality within Cockburn Sound is thought to be low. The most recent information suggests that the pathogen mobility rate is low in local sandy soils, and longevity of bacterial coliforms is likely to be less than 70 days with
32 Status of Groundwater Quality in the Cockburn Sound Catchment
some viruses lasting up to 100 days [see Toze, 1997 for a review of the literature of pathogens in wastewater]. This attenuation of the pathogens in sandy soils is related to the greater potential for adsorption to grain surfaces and the longer flow paths contiguous to natural biofilms in the tortuous pore spaces. However, in soils displaying preferential flows, e.g. Tamala Limestone, the high flow velocities in large macropores and secondary voids could be associated with greater longevity and mobility of pathogens. There is little quantitative evidence available on the mobility and longevity of pathogens in the Cockburn Sound aquifers.
Faced with the lack of quantitative data on pathogen fate in the local aquifers, environmental managers have developed a practice of maintaining setback distances between pathogen sources and the Cockburn Sound shoreline. Where possible, sewage infill is also used to reduce direct pathogen input to groundwater near the shore. Setbacks of 50 m or more are reported for septic tank systems in the Rockingham area [DOH/DOF, 2005], with several foreshore systems being converted to sewage lines in recent years. Pathogen levels are routinely monitored in Cockburn Sound and the shellfish production areas by DoH and DoF.
2.2.3 GROUNDWATER CONTAMINANT PROCESSES
The principal processes governing the persistence and mobility of chemicals in groundwater are • Groundwater flow or advection, which is controlled by the intrinsic rate of water movement through the aquifer matrix (the hydraulic conductivity), the amount or open pore space of the aquifer (the porosity) and the change in the water table elevation with distance in the aquifer (the hydraulic gradient); • Dilution processes such as hydrodynamic dispersion (which occurs when groundwater flows) and diffusion (which occurs regardless of groundwater flow); • Retardation of the movement of chemicals of interest via adsorption of chemicals onto the matrix of the aquifer as the groundwater passes through; • Abiotic reactions, which occur without the need for microbiological action, and may lead to precipitation or transformation of chemicals; • Microbiologically mediated reaction that may biodegrade or transform some chemicals and which may lead to precipitation or entrapment of other chemicals.
2.2.3.1 GROUNDWATER FLOW Groundwater flow conditions within the catchment were discussed earlier (see Section 2.1.7). In summary, groundwater primarily flows to Cockburn Sound via either the shallow Safety Bay Sand aquifer, or through the Tamala Limestone aquifer. Although both aquifers are permeable, the hydraulic properties of these two aquifers are quite distinct. The Safety Bay sand has estimated hydraulic conductivities that range from 1 to 50 m/day (see, e.g., Davidson [1995]), and the Tamala Limestone aquifer has hydraulic conductivities that range up to several hundred m/day (see Smith et al. [2003]). Based on these estimates and those for groundwater gradients and porosities, groundwater velocities have been estimated at 10-100 m/year in the Safety Bay sand and much higher for the Tamala Limestone. Clearly movement of contamination in the Tamala Limestone can be quite rapid. Furthermore, because of the existence of secondary voids and channels in the limestone, the flow through the limestone can be highly variable in a spatial sense, i.e. there can be low flow rates in zones of the limestone that are well cemented, but nearby there can be very high flow rates through networks of voids,
33 channels and fractures. It is hard to imagine a more difficult flow system in which to manage groundwater contamination.
2.2.3.2 HYDRODYNAMIC DISPERSION Hydrodynamic dispersion occurs due to the net effects of fine and large scale variations in the velocity of movement of groundwater. This leads to particles of water (and dissolved chemicals) in different locations moving faster and slower than the average groundwater flow. This in turn leads to greater mixing of groundwater of different chemical compositions. In the near-homogeneous sand aquifers of Perth, dispersion has been shown to be small (see, e.g., Thierrin et al. [1995] and Prommer et al. [2002]) – perhaps with dispersivities in the order of millimetres to centimetres. Such small dispersion coefficients (the dispersion coefficient is most often assumed to be the groundwater velocity multiplied by the dispersivity) lead to limited mixing and dilution of plume concentrations and as such can lead to ‘well preserved’ plumes with high core concentrations and perhaps steep concentration gradients at the fringes of plumes. On the other hand, highly heterogeneous aquifers that exhibit secondary porosity and channel features can cause groundwater flows to show significant preferential pathways. In such cases, simple dispersion concepts may not apply [Trefry et al., 2003]. The Tamala Limestone unit is a candidate highly heterogeneous aquifer, meaning that measurement and/or prediction of contaminant fluxes through the limestone unit can be extremely problematic.
Diffusion is usually a smaller scale process than hydrodynamic dispersion and is caused by mass transfer along concentration gradients – which leads to equalisation of chemical concentrations. However, diffusion coefficients in water (i.e. groundwater) are small, which implies that the timescales for diffusion to equilibrate concentrations over relatively small travel distances may be decades to centuries. For this reason, the effects of diffusion are often neglected in comparison to hydrodynamic dispersion and other effects.
2.2.3.3 DISSOLUTION Some classes of liquid chemicals do not readily mix with water, so when these chemicals are released to the soil they can migrate to the water table and form layers or even emulsions. In these situations, different liquids can co-exist side by side in the aquifer. This is referred to as a multiphase system, where the aqueous (water) liquid phase co- exists with one or more non-aqueous phase liquids (NAPLs). Examples of NAPLs include diesel, TCE and naphthalene. As these NAPLs reside in the subsurface, they can dissolve into the groundwater. As the groundwater moves past the NAPL contaminated zone, the dissolution continues, resulting in a dissolved phase plume in the groundwater. Many NAPLs dissolve slowly, meaning that they can represent sources of long-term groundwater contamination. For some NAPL species, the dissolved phase contaminants have shown to induce carcinogenic responses in mammals. Even so, ecosystems often have some intrinsic capacity to absorb or reduce dissolved phase contamination, thereby limiting impacts of contamination.
2.2.3.4 VOLATILISATION Some NAPL and dissolved contaminations are also volatile, i.e. the NAPL or groundwater species can vaporize under normal temperature and pressure conditions, transferring the chemical species into soil gas or the atmosphere. Analogous to NAPL dissolution, the volatilities of many NAPLs are low, potentially leading to long-lived and persistent vapour contamination near NAPL sources. Examples of volatile compounds are the BTEX volatile organic compounds, i.e. benzene, toluene, ethylbenzene and the xylene isomers.
2.2.3.5 SORPTION Aquifer sediments are not benign – and can interact with solutes in groundwater to act as surfaces for the adsorption of contaminants. Typically, organic compounds will adsorb into organic matter that may coat soil grains. Metals and some other chemicals may not
34 Status of Groundwater Quality in the Cockburn Sound Catchment
respond to organic matter, but may adsorb or exchange with mineral phases such as iron or aluminium oxides present on the soil surface. These exchange and adsorption processes lead to the retardation of the peak concentration of a chemical as it passes through the aquifer in groundwater. This leads to a delay in its travel time from source zones to receptor or discharge locations.
2.2.3.6 BIODEGRADATION Biodegradation within groundwater relies on microbial processes to mineralise or transform contaminants (usually organic contaminants) into less toxic forms. Critical to the success of biodegradation is the presence in groundwater or soil of bacteria (or other biota) capable of degrading the chemical of interest, and the geochemical conditions that allow biodegradation to proceed. In particular, biodegradation relies on the presence of an organic substrate, an appropriate microbial community, suitable electron acceptor (or donor), moisture, nutrients (e.g., nitrogen and phosphorus), and trace elements. Limitations in any one factor may indeed limit microbial processes and the potential to reduce chemical concentrations naturally in groundwater. For example, petroleum hydrocarbons will often naturally degrade in groundwater if electron acceptors such as oxygen, nitrate, iron oxides, sulphate or carbon dioxide are present in groundwater. If these electron acceptors are absent due to earlier use by microbes, for example, then petroleum hydrocarbons may persist in groundwater. Studies in northern Perth (near Eden Hill) have shown a benzene plume in groundwater that appeared resistant to biodegradation and as a result it extended over 400 m away from the source of the spill (see Davis et al. [1999]). Specific studies at the BP Refinery within the Cockburn Sound catchment have shown significant mass removal and seemingly complete biodegradation of benzene with truncated plumes maybe 20-50 m long. Biodegradation appears to be happening under methanogenic conditions – with microbes utilizing carbon dioxide to degrade the petroleum components, especially benzene.
3 Pressures on Cockburn Sound Groundwater
3.1 DEVELOPMENT IN COCKBURN SOUND
3.1.1 FIRST INHABITANTS The original human inhabitants of the Cockburn Sound area were the aboriginal peoples, who are thought to have established a permanent presence in the Swan Coastal Plain approximately 40 000 years ago [see O’Connor, 2001 and references therein]. With the fluctuations of sea level induced by global climatic variations, the local coastline altered dramatically for the next 35 000 years. The last major change saw the flooding of interdunal depressions and the submersion of all but the highest dune ridges, forming a feature now known as the Garden Island Ridge; Garden Island, Carnac Island and Rottnest Island are obvious outcrops. This change occurred approximately 6 000 years ago, and formed the embayment of Cockburn Sound as we know it today. The neighbouring mainland area was inhabited by the Beeliar people, a local sub-group of the Whadjug dialect group. These peoples formed a complex and intimate association with the land and with neighbouring peoples. Cockburn Sound provided a source of marine foods to the Beeliar people, supplemented by freshwater species from the inland lakes and wetlands and foodstuffs from terrestrial flora and fauna.
35 3.1.2 EUROPEAN SETTLEMENT European exploration reached the Swan-Cockburn area in the early 17th century and the first local settlement was established by the British in the area in 1829 by a fleet under the command of Captain James Stirling, at Garden Island. Like the Beeliar people, the Europeans soon learnt the value of Cockburn Sound as a source of food supply, transportation and recreation. This close relationship with Cockburn Sound survives to this day throughout the community of Western Australia. After some trying times, the Swan River Settlement was consolidated with agricultural and mining industries and a period of rapid growth ensued. Over the decades following the Second World War, during which Cockburn Sound housed an ammunitions store at Woodman Point (Figure 3.1), the community of Western Australia faced an influx of migrants from Europe and a need to expand industrialisation. Because of its proximity to a major population centre and its sheltered marine aspect, Cockburn Sound was chosen as a site of a major oil refinery in the 1950’s; operations at the BP Refinery commenced in 1955 [DoCE, 1979]. Other industries and businesses followed, forming a major industrial strip along the Kwinana beachfront and generating undoubted economic and social benefits for Western Australia. By the 1960’s there were concerns that industrial activities were detrimentally affecting seagrasses and other aquatic life in the Sound. In the early 1970’s the Causeway between Point Peron and Careening Bay on Garden Island was completed in order to support developments and operations of HMAS Stirling. The Causeway altered the natural seawater circulation patterns in the Sound, altering flushing and changing beach depositional dynamics. After a period of hot and calm summer weather, a major algal bloom covered almost half of the sea area between the mainland and Garden Island (Figure 3.2), highlighting the eutrophic nature of the Sound. Horticultural activities were also expanding within the catchment at this time.
3.1.3 ENVIRONMENTAL IMPACTS Environmental management of the Sound was hampered because of the legislative Acts governing industrial activities in the Sound. A major review of the environmental state of the Sound was commissioned by the WA Government in 1976 and completed in 1979 [DoCE, 1979]. The study identified significant nutrient and toxicant levels in the seawater which were correlated with contaminated seafood and widespread loss of natural seagrass meadows within Cockburn Sound. In terms of groundwater, plumes of contaminated groundwater were identified and associated with individual industrial sites. Groundwater abstraction rates were found to be too high, leading to intrusion of saline wedges inland from the coast. Together the industries in the Kwinana strip established the Kwinana Industries Forum in order to inform industries about environmental issues and to coordinate industry response to community concerns. By the mid-1980’s the WA Government had introduced new environmental legislation that overrode previous industry Acts. In response to studies on the impact of direct waste discharges to the Sound during the 1980s [see DEP, 1996], unregulated discharge to the Sound of industrial effluents was curtailed, reducing direct inputs of nutrients and heavy metals and leading to an improvement of seawater quality. Aquaculture industries have been operating within the Sound under the auspices of the Western Australian Shellfish Quality Assurance Program since 1994; testing shows that shellfish from the area have conformed to Australian export standards over the past four years [DoH/DoF, 2005]. Recent wastewater management initiatives have reduced further the discharge of industrial wastewater directly to the Sound.
36 Status of Groundwater Quality in the Cockburn Sound Catchment
Figure 3.1: Aerial photograph of the Woodman Point munitions store. Image scanned from a WA Department of Environment photo taken in 1984.
37
Figure 3.2: Aerial photograph of an intense algal bloom in Cockburn Sound during the summer of 1973-74. Image reproduced from a scan of Plate 11 of DoCE [1979].
38 Status of Groundwater Quality in the Cockburn Sound Catchment
In the early 1990’s the Kwinana Industries Forum was dissolved and replaced by the Kwinana Industries Council (KIC) with membership covering the majority of major industries in the Kwinana Industrial Area. KIC maintained the environmental coordination role of the former Forum and broadened its membership base. About the same time, environmental studies of the Cockburn Sound catchment identified continuing threats to seawater quality from groundwater contaminated by nutrients [Hirschberg, 1991; Appleyard, 1990, 1994]. The Southern Metropolitan Coastal Waters Study [DEP, 1996] further raised awareness of the linkages between industrial activity and environmental degradation in the Sound. The Cockburn Sound Management Council was established by the State government in 2000 with a brief to coordinate environmental planning and management of Cockburn Sound and its catchment.
3.1.4 URBAN DEVELOPMENT Urban pressures are also growing within the catchment. Information from regional planners indicates that the South-West Metropolitan Sector, comprising land from Cockburn, Rockingham and Kwinana, is expected to be the fastest growing residential sector over the next 5-10 years, with over 18 000 residential lots forecast to be developed in the sector [WAPC, 2004], see Figure 1.3. The sector is projected to have the largest population growth in the metropolitan area over the next 5 years, across all human age groups. Infill sewage activities are continuing within the catchment, especially in new land releases near Kwinana. It is worth noting that the Kwinana industrial strip remains unsewered. These urbanization pressures have resulted in escalating land valuations and the consequent departure of large-scale horticultural businesses from the catchment; most of these have moved to less expensive premises further south. New urban infrastructure for roads, rail, education and health are all planned for the South-West Sector. In Rockingham, new coastal developments are being built or planned, including the Cape Peron Tourist Precinct.
Referring to Figure 1.3, we see that the catchment is in a busy phase of redevelopment and urbanization with many improvements or constructions planned. These include significant water upgrades, new and improved education facilities, and the extension of the railway from metropolitan Perth to Mandurah.
Figure 1.4 shows a number of costal developments planned or proposed for Cockburn Sound, including several major port and harbour expansions, including a 57 hectare reclamation of the Sound at James Point (Kwinana Port), a 100 hectare artificial island construction further north (FPA Port) and a proposed major marina complex for Point Peron/Mangles Bay (Cape Peron Tourist Precinct).
3.1.5 INDUSTRIAL DEVELOPMENT The Kwinana industrial strip has grown to be the dominant economic force within the catchment, totalling almost $9 billion dollars in annual output and employing 4000 staff directly (70% living locally) and another 24000 indirectly [KIC, 2002]. HMAS Stirling is also a major economic force for the region, although its work rate is less consistent. The Australian Marine Complex south of Woodman Point now directly employs several thousand people in shipbuilding and allied industries. The industries in the Australian Marine Complex will benefit from new government investment in shared facilities. A new technology precinct for the Australian Marine Complex is being established on the south- eastern shore of Lake Coogee. Major new industrial initiatives are underway in Hope Valley and James Point. The Hope Valley-Wattleup redevelopment will see 1270 ha of land rezoned for industrial use, forming a second significant industrial precinct in the catchment. Construction of the Perth Seawater Desalination Plant is due for completion in
39 2006, and the Kwinana Water Reclamation Plant came on line in late 2004. Within the Sound itself, other significant developments are proposed (see Figure 1.4). These include the James Point Port/Outer Harbour development, which proposes to reclaim 20 ha of the Sound for dry land access. At least a further 57 ha of the Sound are proposed to be dredged to improve shipping access to the new port facilities. Extra transportation infrastructure is proposed on the mainland to support freight and livestock activities associated with the new port operations. Fishing and aquaculture industries are also active in Cockburn Sound.
3.1.6 GROUNDWATER – THE HIDDEN INPUT Environmental management of the Sound and its catchment is a complex task. There are many subtle interrelationships between numerous commercial, industrial, environmental and community interests in the system. Many interests are complementary, for example some ecosystem species can benefit from enhanced nutrient levels in the Sound, whilst other interests compete directly with each other. Whilst some surface water processes are often obvious to the lay person and many aspects of surface water ecology are well understood scientifically, the scientific community has only recently begun to tackle the question of assessing ecosystem impacts from groundwater contamination. In many respects, the subterranean nature of groundwater processes has hidden them from mainstream community view.
Groundwater is a finite resource, being replenished by rainfall and moving slowly but inexorably towards rivers and coasts where it ultimately discharges into the sea. As it moves, it can carry with it a variety of kinds of contamination. These kinds can be divided into two simple classes: diffuse contamination, which originates from practices or phenomena occurring at catchment scales or wider; and point source contamination, which originates from localised emissions or discharges of contaminants. In the main, both kinds of contaminations are difficult to address. Diffuse contamination is often problematic because the spatial scale of the contaminating process makes it difficult to institute and enforce consistent management responses. On the other hand, point source contamination can be difficult even to locate and characterize because of the uncertainties associated with natural variability of soil and aquifer properties. A final complicating factor is the expense associated with subsurface investigations – comprehensive drilling programs are costly and have no guarantee of success because of the unknown variations in subsurface conditions.
Nevertheless, some studies have correlated groundwater contamination with ecosystem impacts in surface waters, although exact quantitative impact assessments are often scarce in the scientific literature [Rosich et al., 1994]. In the case of Cockburn Sound, the spectrum of potential contaminants that may reach the Sound via groundwater pathways is very broad and so the development of exact and comprehensive environmental management responses to each potential threat is not yet possible; a guideline approach to protecting environmental values is required. In the following sections we attempt to summarise basic scientific concepts of groundwater and contaminant hydrology within the Cockburn Sound context. Our hope is that this summary will serve as a starting point for future research in the area, and as an interpretive resource for regulators, industry and the community.
40 Status of Groundwater Quality in the Cockburn Sound Catchment
3.2 GROUNDWATER QUALITY IN THE CATCHMENT
3.2.1 NUTRIENT FLUXES TO COCKBURN SOUND The Cockburn Sound catchment supports a variety of industrial, urban and rural land uses and is thus vulnerable to both point source and diffuse contaminations. Three decades ago, nutrient concentrations in groundwater were identified as potential threats to water quality in Cockburn Sound [DoCE, 1979]. However no quantitative estimates of nutrient discharge flux to the Sound were made in that report, although discharges of nitrogen and phosphorus to the Sound from industrial effluents were estimated to be approximately 1825 tonnes per year and 1460 tonnes per year, respectively. Since that time, a series of estimates have been made of the annual input of nutrients to the Sound from groundwater. These are listed in Table 3.1.
A common theme of these studies is the inherent uncertainty of the estimates: the stated estimates have very large ranges of uncertainty which are due to the limited numbers of measurements available and to the variability of aquifer properties and groundwater fluxes, as discussed in previous sections. Table 3.1 shows that the estimated groundwater nutrient fluxes have not changed dramatically since the first estimate in 1990, even though the total nutrient fluxes to Cockburn Sound have declined through improved management of stormwater and industrial effluents. The most recent studies attempted to quantify the uncertainties associated with the nutrient estimates; the uncertainties were still high and the need for improved understanding of local-scale groundwater discharge processes was emphasised.
Study Nitrogen Phosphorus (t/year) (t/year) Appleyard [1990] 200 ± ? 4 Mackie-Martin [1992] 350 ± ? - Appleyard [1994] 330 ± 100 2 DEP [1996] 340 ± ? - DAL [2001] 212 ± ? 23 ± ? Smith et al. [2003] 234 ± 88 - Smith and Johnston [2003] 345 ± 138 (groundwater) - 206 ± 75 (submarine porewater)
Table 3.1: Estimated nutrient discharges to Cockburn Sound from groundwater.
The situation is further confused in an environmental management sense by the difficulty of apportioning the nutrient load between different land uses, i.e. industrial versus horticultural versus urban. Intensive fertilizer applications in horticultural zones were associated with widespread elevated nitrogen levels in groundwater in the early 1990s (up to 80 mg/L nitrogen, Pionke et al. [1990]). The lack of deep sewage in some parts of Kwinana, Hope Valley and throughout the industrial strip is also a potential source of nutrients. Various industrial sites are significant sources of nutrients, including the ammonium sulphate plumes near Lake Cooloongup, the sewage and wastewater treatment plants at Kwinana, Point Peron, Woodman Point and Garden Island, and the fertilizer producing industries on the coast.
41 Tracking the origins and evolution of nutrient contaminations across the catchment requires a consistent groundwater quality monitoring plan. In the past, DoE maintained a water quality monitoring program within the catchment, although its coverage was incomplete (see Figure 3.3). According to DoE data, this monitoring effort appeared to cease by 2000. Data from licensed premises can be used to supplement studies of nutrient concentrations [see Smith et al., 2003], however this data tends to come from bores clustered near the coast and gives little assistance in building a catchment-scale picture of groundwater quality. The planned urbanisation of the catchment, together with the findings of previous studies performed elsewhere on the Swan Coastal Plain that associate rising nutrient levels with increasing urbanisation, provide strong motivations for reviving a comprehensive catchment water quality monitoring program. For these reasons, no effort was made here in generating an updated estimate of nutrient discharge flux to the Sound – there is simply insufficient data with which to improve upon earlier estimates. What is required is a concerted and spatially representative sampling effort, starting at the eastern margins of the Cockburn Sound catchment where “background” nutrient concentrations are imposed and covering the body of the catchment.
3.2.2 BACKGROUND NUTRIENT LEVELS Since groundwater flows predominantly from east to west through the catchment, it is instructive to examine the available water quality data along the eastern edge of the catchment. Water Corporation maintains a set of drinking water production bores located on the Jandakot Mound, just beyond the north-eastern boundary of the Cockburn Sound catchment. Water from these bores is first treated to potable quality and is then fed into the potable supply for the Perth Metropolitan area. Water quality indicators have been measured regularly for the Jandakot production bores since the 1970s, which allows estimates of the background (upstream) nutrient concentrations in the Cockburn Sound groundwater. Tables 3.2 and 3.3 list nitrogen oxides and ammonia concentrations, respectively, at the production bores, averaged both over the monitored life of each bore and over the past 6 years from 1 January 2000. In the following text, references to trigger values relate to the ANZECC/ARMCANZ Guidelines for Fresh and Marine Water Quality [2000] trigger values for slightly disturbed inshore marine ecosystems in south-west Australia, while references to drinking water guidelines relate to the NHMRC Drinking Water Guidelines [2004].
Table 3.2 shows that the nitrate+nitrite concentrations are relatively stable, i.e. the six- year average concentrations are similar to or below the lifetime average concentrations in each bore. Overall, the nitrogen oxides levels in the production bores are close to the ANZECC/ARMCANZ marine trigger values of 5 μg/L (see Table 4.2) and the freshwater trigger values of 10 μg/L (see Table 4.3), and well below the relevant NHMRC drinking water guidelines values (see Table 4.3). Exceptions are Jandakot bores 120, 230 and 380 where the measured nitrate+nitrite concentrations are above the marine trigger values and rising. On the other hand, Table 3.3 shows that ammonia levels in the production bores are typically well above the marine trigger values (5 μg/L for ammonia and 230 μg/L for total nitrogen species) of Table 4.2 and often exceed the drinking water aesthetic guidelines. Furthermore, the observations indicate an increasing trend in the ammonia concentrations for nearly all production bores. The origin of this trend is unclear; one possible explanation is that the trend is a result of the increasing urbanisation of the Jandakot area. As a whole, the nutrient data shows that the Jandakot Mound supplies water of moderate quality to the Cockburn Sound groundwater system, and that this water quality (with respect to nitrogen levels) has been in measurable decline over the last six years at least.
42 Status of Groundwater Quality in the Cockburn Sound Catchment
Figure 3.3: Most recent sampling for nutrients by DoE referenced by location in the Cockburn Sound catchment. Data supplied by DoE from the WIN database. Monitoring bores operated by industry and other stakeholders in the catchment are not shown.
43
Lifetime 1 Jan 2000 onwards Production Bore Min Ave Max Min Ave Max Jandakot 10 3.5 22.7 119.9 7.0 10.0 13.0 Jandakot 20 3.9 22.5 206.2 9.0 13.5 18.0 Jandakot 30 2.2 20.7 146.0 8.0 8.5 9.0 Jandakot 40 3.3 15.9 67.0 5.0 5.0 5.0 Jandakot 45 3.9 24.3 299.0 5.0 11.0 17.0 Jandakot 50 1.8 16.1 88.5 4.0 4.0 4.0 Jandakot 60 2.3 17.4 107.9 5.0 6.0 7.0 Jandakot 70 2.0 24.9 120.4 2.0 6.5 11.0 Jandakot 90 2.7 20.4 120.0 4.0 6.0 8.0 Jandakot 105 1.1 10.1 42.0 4.0 6.0 8.0 Jandakot 110 2.1 20.5 103.1 7.0 7.0 7.0 Jandakot 120 1.6 17.3 68.5 5.0 24.5 44.0 Jandakot 130 1.7 15.1 86.0 7.0 8.0 9.0 Jandakot 140 2.8 12.7 49.3 5.0 9.5 14.0 Jandakot 150 2.3 21.5 76.3 - - - Jandakot 210 2.0 7.1 19.0 5.0 5.0 5.0 Jandakot 220 2.4 10.6 38.0 4.0 4.5 5.0 Jandakot 230 4.0 20.7 47.0 4.0 25.5 47.0 Jandakot 240 4.3 12.1 22.9 6.0 8.0 10.0 Jandakot 250 9.6 28.0 70.8 - - - Jandakot 270 3.0 14.9 53.0 5.0 7.0 9.0 Jandakot 320 2.5 13.5 57.0 5.0 5.5 6.0 Jandakot 360 2.5 8.2 22.0 4.0 5.0 6.0 Jandakot 370 2.0 13.3 57.4 2.0 6.0 10.0 Jandakot 380 60.9 107.9 230.0 100.0 150.0 230.0 Jandakot 390 2.0 15.0 62.0 2.0 3.0 4.0 Jandakot 400 3.0 14.7 51.0 3.0 4.5 6.0 Jandakot 410 2.0 6.0 20.0 2.0 2.0 2.0 Averages 4.9 19.8 87.5 8.6 13.5 19.8
Table 3.2: Historical nutrient data for untreated groundwater extracted from Water Corporation production bores at Jandakot Mount. Concentrations are specified in units of μg (N)/L for combined NO2 and NO3 species. Underlined terms indicate instances where the six-year value is greater than or equal to the corresponding lifetime value. Data supplied by Water Corporation.
44 Status of Groundwater Quality in the Cockburn Sound Catchment
Lifetime 1 Jan 2000 onwards Production Bore Min Ave Max Min Ave Max Jandakot 10 57 502 655 480 538 560 Jandakot 20 107 523 737 520 560 590 Jandakot 30 9 468 647 500 532 550 Jandakot 40 5 336 498 360 370 390 Jandakot 45 315 550 797 580 598 610 Jandakot 50 3 271 466 100 238 290 Jandakot 60 3 234 342 280 296 320 Jandakot 70 6 156 280 240 258 280 Jandakot 90 177 428 600 440 478 520 Jandakot 105 27 533 895 27 209 350 Jandakot 110 3 103 728 80 97 120 Jandakot 120 83 255 320 270 294 320 Jandakot 130 29 367 710 500 614 710 Jandakot 140 102 497 612 530 552 580 Jandakot 150 39 210 412 230 230 230 Jandakot 210 116 644 963 430 472 530 Jandakot 220 190 246 390 220 244 270 Jandakot 230 167 428 510 470 494 510 Jandakot 240 406 484 639 420 428 440 Jandakot 250 451 567 620 590 603 620 Jandakot 270 14 262 410 330 368 410 Jandakot 320 5 31 55 20 35 55 Jandakot 360 8 149 305 190 222 250 Jandakot 370 13 99 160 130 146 160 Jandakot 380 10 25 55 23 32 55 Jandakot 390 16 173 270 200 210 220 Jandakot 400 92 181 250 170 180 190 Jandakot 410 8 91 171 120 136 150 Averages 88 314 482 302 337 367
Table 3.3: Historical nutrient data for untreated groundwater extracted from Water Corporation production bores at Jandakot Mount. Concentrations are specified in units of μg (N)/L for NH3 (ammonia). Underlined terms indicate instances where the six-year value is greater than or equal to the corresponding lifetime value. Data supplied by Water Corporation.
45
Monitoring NO2+NO3 NH3,4 Bore Location Min Ave Max Min Ave Max (WIN ID) 3333 Thomson’s Lake 2 45 154 225 476 771 9373997b Lake Banganup 22 22 22 124 124 124 9387429b Lake Banganup 4 4 4 27 27 27 9963955 Thomson’s Lake 2 5 13 436 505 545 10022456b Jandakot Aquifer 40 40 40 114 114 114 12078898a The Spectacles 5 20 59 5480 6566 7790 12078901a The Spectacles 3 10 31 5160 6329 7540 12078904a The Spectacles 1 7 23 3844 5108 6415 12078907a The Spectacles 2 8 16 254 568 894 14804312b Cockburn Salt 10256 10256 10256 - - - Averagesc 9 18 40 1740 2202 2691
Table 3.4: Historical nutrient data for groundwater extracted from DoE/WIN monitoring bores within the Cockburn Sound catchment. Concentrations are specified in units of μg (N)/L for total nitrogen oxides (NO2+NO3) and for NH3,4 (ammonia/ammonium species) over the period February 1994 – April 1998. a bores for which nitrogen oxides outlier readings of 1000 μg/L were removed; b single reading; c ignoring Cockburn Salt location. Data supplied by Department of Environment.
46 Status of Groundwater Quality in the Cockburn Sound Catchment
Figures 3.4 and 3.5 summarise the nutrient data presented in Tables 3.2 and 3.3, respectively. In the Figures, yellow symbols indicate bores where water quality indicators were measured to be above the relevant marine trigger values, and blue symbols where values were beneath marine trigger values. It is important to note that the tables and figures include data that were measured at different times: the production bore data to the east of the catchment is more recent than the DoE/WIN data within the catchment which ceased in 1999.
There is a very limited DoE data set available for several monitoring locations inside the catchment. Table 3.3 presents a part of the WIN data set, comprising nitrogen-related nutrient levels measured in groundwater between 1994 and 1998. The prime foci of this data set are the Thomson’s Lake area and The Spectacles. Again, the nitrogen oxide levels are far above the marine trigger values and are well below the drinking water guidelines. There are some instances of higher oxide levels near the two lake systems. By contrast, the ammonia concentrations are significant near Thomson’s Lake and are very high at The Spectacles, well above drinking water guidelines, supporting the need for nutrient stripping treatments for the Peel Main Drain [Khan and Zubair, 2001]. This may be a result of nutrient-rich stormwater and runoff drainage into the wetlands finding its way to the water table. The Spectacles are part of the Peel Main Drain system, draining excess water from the horticultural properties in the north and east regions of the Cockburn Sound catchment. In this sense, the natural topographic drainage features can themselves present significant (albeit indirect) threats to groundwater quality simply by attracting nutrient-rich runoff. Once the nutrients enter the wetlands, there is potential for transfer of contaminants to the groundwater systems below [Townley et al., 1993]. If this is true, then (in the absence of direct groundwater data) surface water quality data may be used as a qualitative indicator of groundwater health. Surface water quality data for Kogolup Lake and Yangebup Lake, both lying immediately to the north of Thomson’s Lake, are presented by Martinick McNulty [2000]. In that report, the average total nitrogen concentrations for the surface water in each of the two lakes from 1995-1999 exceeded 4 000 μg/L. The South Jandakot Rural Drain was a prime source of this nutrient load, contributing total nitrogen concentrations of 8 000 μg/L over 1995-1998, although the South Lakes Drain also contributed significant concentrations [Martinick McNulty, 2000]. Table 3.3 also shows a single large ammoniacal nitrogen measurement at the Cockburn Salt monitoring location near the coast.
The Jandakot Mound serves as a boundary condition for the Cockburn Sound catchment. Nitrogen concentrations entering the catchment from the Mound are likely to be preserved in the catchment groundwater, unless denitrification processes occur. Denitrification of the nitrogen oxides takes place predominantly in anaerobic zones, or where de-oxygenated waters mix with nutrient-rich groundwater. As stated in section 2.2.2.1, denitrification is less common in the Cockburn Sound aquifers, so the Jandakot nutrient levels may present a useful lower bound to the nitrogen concentrations in groundwater across the catchment. In other words, should all urban and industrial activity and contamination effects cease immediately in Cockburn Sound catchment, it is likely that the groundwater fluids discharging to the Sound would continue to contain average nutrient concentrations above the marine trigger values, and that these levels would tend to increase over time.
Of course, urban and industrial activities will not cease in the short to medium term, so it is probable that local groundwater nutrient concentrations will register significantly above the background Jandakot Mound levels. The industrial and urban redevelopment initiatives planned for the catchment will almost unavoidably impact groundwater quality. It remains to be seen whether the impact will improve water quality or not. However, in the absence of significant denitrification processes, any nutrient input to the groundwater will eventually discharge into Cockburn Sound (nitrogen in surface waters is readily utilized by epiphytes).
47
Figure 3.4: Measurements of oxides of nitrogen levels for the Cockburn Sound catchment. Data supplied by DoE and Water Corporation. The ANZECC/ARMCANZ marine trigger value is 5 μg/L.
48 Status of Groundwater Quality in the Cockburn Sound Catchment
Figure 3.5: Measurements of ammonia levels for the Cockburn Sound catchment. Data supplied by DoE and Water Corporation. The ANZECC/ARMCANZ marine trigger value is 5 μg/L.
49 3.2.2.1 BACKGROUND WATER QUALITY SCENARIOS As a simple indication of potential impact, we can estimate the net nutrient discharge to Cockburn Sound from diffuse sources high in the catchment under different water quality scenarios. According to Smith and Johnston [2003], the length of Cockburn Sound shoreline is L = 13.7 km and the groundwater discharge flux varies between 2.8 and 5.5 m3 d-1 m-1. Here we assume that the mean groundwater discharge flux everywhere along 3 -1 -1 the coast is qgw = (2.8+5.5)/2 = 4.15 m d m . To complete the calculation, all we require is an estimate of mean nutrient concentration in the groundwater discharging at the shore.
First we consider the ideal scenario where background water quality meets the inshore marine trigger values. Thus, adding the respective ideal marine trigger values for NOx and NH3, the total “nitrogen species” concentration would be cmean = 10 μg/L, and the resulting input is given by the product L x qgw x cmean = 0.2 tonnes per year, which is negligible in comparison to the nutrient inputs listed in Table 3.1. In the second scenario we consider the freshwater trigger values, where the nitrogen species concentration amounts to cmean = 20 μg/L, yielding a nitrogen input of 0.4 tonnes per year. Now, for the third scenario, if we consider that the groundwater is contaminated with nutrients to the limit of drinking
water standards, cmean = 55500 μg/L (55.5 mg/L). In this case the annual diffuse nutrient input evaluates to 1152 tonnes per annum, well above the estimated actual inputs based on porewater nutrient sampling performed by Smith and Hick [2003]. Finally, we consider a background water quality scenario based on the data in Tables 3.2-3.4 for the Jandakot production bores and the DoE bores, i.e. assuming that these data are representative of the general nutrient concentrations high in the catchment. Taking the average of the sum of the nitrogen oxides and ammonia concentrations across the 28 Jandakot bores (2000 onwards) and the 9 DoE WIN database bores (1994-1999, excluding Cockburn Salt) yields a mean nitrogen species concentration of 805 μg/L which equates to a net nitrogen species flux to the Sound of almost 17 tonnes per annum. These hypothetical scenario estimates are summarised in Table 3.5.
The mean concentration for Scenario 4 is not incompatible with the previous porewater surveys, and the associated nitrogen species input is approximately 7% of the 234 tonnes per year groundwater nutrient input quoted recently for the Sound [Smith and Johnston, 2003]. Under this hypothetical scenario, the balance of the 234 tonnes may be attributed to point source nutrient contaminations near Northern Harbour, James Point and further south. However, we stress that the scenario analysis is not intended to provide a formal estimate of background nutrient inputs to the Sound. Rather, the scenario analysis is meant to highlight the potential impacts associated with rising nutrient levels inland in the catchment and the need for improved monitoring and data gathering for this contamination pathway. A background total N concentration of 11000 μg/L (or 11 mg/L) throughout the catchment would be sufficient to equate to an extra 230 tonnes of nutrient discharge to Cockburn Sound per year, i.e. doubling the present input.
Scenario Basis of Scenario Nitrogen Species Nitrogen Species Input cmean (μg/L) (t/year) 1 Marine Trigger Values 10 0.2 2 Freshwater Trigger Values 20 0.4 3 Drinking Water Guidelines 55500 1151.7 4 Jandakot + DoE/WIN 805 16.7
Table 3.5: Hypothetical nutrient discharges to Cockburn Sound from background concentrations in groundwater. Scenarios assume that groundwater of the indicated quality is discharging to Cockburn Sound along the full 13.7 km length of shore. Nitrogen Species is defined as the sum of NO2, NO3 and NH3 concentrations. ANZECC/ARMCANZ trigger values; NHMRC drinking water guidelines.
50 Status of Groundwater Quality in the Cockburn Sound Catchment
The foregoing analysis is based on the limited data available. There is insufficient detail to build a clear understanding of the current state of nutrient levels across the catchment, especially in respect to tracking the effects and inputs of both point and diffuse sources of nutrient contamination. This situation represents a strategic weakness for the environmental management both of the catchment’s groundwater resource and of its prime receptor, Cockburn Sound. It is vital that a regular monitoring network be established for the catchment in order to inform the management of groundwater quality underneath all existing and planned land uses. Ideally, the monitoring effort would source water quality data from prescribed premises and elsewhere at commercial/industrial precincts, urban centres and semi-rural zones, thereby building a comprehensive database of water quality time series across the catchment. The goal here is to establish baseline data prior to the commissioning of the Hope Valley/Wattleup industrial redevelopment and the further urban initiatives elsewhere in the catchment, so that the impacts of these initiatives can clearly be discerned and managed.
3.2.3 ASSESSING HUMAN IMPACTS A useful picture of the actual impact of human activities on nutrient levels throughout the catchment is given by Smith and Johnston [2003]. In that report, instances are given of nutrient concentrations almost three orders of magnitude higher than the inland Jandakot production bore concentrations. The major sites of point-scale nutrient contamination were recorded in Smith and Johnston [2003] as (i) the coastal area south of James Point (in the vicinity of BP, CSBP, Fremantle Port Authority), (ii) the Bulk Terminal area north of James Point (in the vicinity of HIsmelt, Cockburn Cement) and (iii) the Northern Harbour area (Woodman Point Wastewater Treatment Plant, Nagata/Love Starches). As part of the present study a limited survey of groundwater conditions under licensed industrial premises was made: the results are presented in the next section.
3.3 INSTANCES OF SITE CONTAMINATION In order to rank the threats of contaminants in groundwater to Cockburn Sound, a survey was undertaken of existing information on the presence of contaminants as identified by businesses in the catchment area. This was to identify the contaminants that are of concern, their prevalence and use and the possible exposure pathways for affects to be manifesting in Cockburn Sound. The information was sought directly from businesses, and along with identifying what was known about existing contaminants in groundwater, other information was sought to support a risk weighting methodology that would assist in identifying risk to Cockburn Sound. This other information included the materials that are stored and used as part of operations, groundwater monitoring and management, local hydrogeological conditions and the use of groundwater by businesses.
The scope of the project limited the number of businesses surveyed and the extent of information that could be gathered and reviewed. To enable a well-focussed assessment given these limitations 64 businesses and fifteen government agencies, authorities and associations within the Cockburn Sound catchment were surveyed (see Figure 3.6 and Appendix 3). These were selected according to existing knowledge of their known and potential groundwater contamination as well as factors such as their location and type of operation which may pose a higher level of threat to Cockburn Sound. Thirty-two of these businesses were licensed as prescribed premises.
The survey was initiated with a written request for information on: • recent or historic information or reports on groundwater quality monitoring;
51 • any management implemented for groundwater beneath and in the vicinity of the site, especially any active remediation of groundwater related to the site; • groundwater usage (if any) including the rate of pumping and from which aquifer strata groundwater is recovered • primary chemical storage (e.g., fertilisers, gases, solvents, etc) on the business premises including the types and quantities.
The responses to this survey form the basis for our assessment of the current extent of groundwater contamination and threats posed to Cockburn Sound. A total of 50 responses were received from industry and have been included in the following assessment (see Table 3.6 and Figure 3.6). This included 28 licensed premises. Limitations of the survey and responses are discussed below. Whilst not every business premises has been contacted for the survey, we feel that the range and diversity of premises types gives a fairly good cross-section of the current industrial and commercial activities in the catchment. The responses provide at least a representative picture of the extent and practice of groundwater monitoring within the catchment, and thus constitute a useful data set from which to identify potential gaps in the environmental management of groundwater quality for Cockburn Sound. The responses are summarised below in a series of tables with accompanying comments.
3.3.1 USE AND MONITORING OF GROUNDWATER Only eight of the respondents indicated that they used groundwater as part of their industrial processes with thirteen reporting that they used groundwater for domestic use for irrigating gardens and the like. In the cases of CSBP, Alcoa, BHP Billiton and Western Power’s Kwinana Power Station contaminated groundwater was used as part of the industrial processes and its use integrated with their contaminated groundwater management strategies. Indeed, there was a degree of reuse of groundwater in these instances where groundwater contaminated, typically for water-based conveyance of raw materials and wastes, was recovered, re-used and in some cases process chemicals recovered. This diminished the net use of groundwater. Most groundwater use was from the Superficial Aquifer (mainly the Tamala Limestone but also the Safety Bay Sand), however appreciable volumes were reported to be abstracted from the Yarragadee (CSBP and Cockburn Cement) and Leederville Formation. Locally, some abstractions are significant with respect to the overall water balance. Smith and Johnston [2003] for instance calculated groundwater discharge (and hence groundwater throughflow in the aquifer) from the Superficial Aquifer to Cockburn Sound of 0.9 – 1.8 GL/yr/km of coast line for low and high recharge scenarios. Licensed abstractions from the Superficial Aquifer of equal or greater than 1.5 GL/yr in some instances therefore have the potential to perturb natural groundwater flow regimes. This has been manifest at the near coastal locations of Alcoa’s refinery and the northern boat harbour where there is evidence of saline sea water invading the Superficial Aquifer.
Twenty-five respondents reported some form of groundwater monitoring in place. A further two indicated that they had plans to institute a groundwater monitoring scheme in the near future. Interestingly, some respondents mentioned that they did not monitor groundwater because they did not use groundwater. As anticipated the extent and detail of groundwater monitoring varied greatly – from a one-off sampling of an irrigation bore to regular monitoring of 481 production, recovery and monitoring bores at intervals of one month to one year. Table 3.7 provides information on the aquifers monitored and the major analytes included in the monitoring schemes.
52 Status of Groundwater Quality in the Cockburn Sound Catchment
Figure 3.6: Locations of premises surveyed or relevant to this study. Location data supplied by WA Department of Environment and Water Corporation.
53 3.3.2 ANALYTES MONITORED As shown in Table 3.7, a variety of groundwater analytes and parameters are monitored. Generally, these are tailored to detecting contamination that may arise from the particular processes and materials used on site. However, this is far from being universally true. In some instances, it appears that monitoring schemes are reactive to the occurrence of specific events or the discovery of particular contaminants in groundwater by other than routine monitoring. In at least some instances, e.g. Nalco, routine monitoring may not identify the contamination of groundwater by materials used on site. In the case of Coogee Chemicals, bores around a petroleum hydrocarbon storage facility are only monitored for pH while the monitoring at Nalco, which stored and used large amounts of the industrial organics acrylic acid, acrylamide, poly acrylic acid and poly acrylamide, did not report any measures of these in the sampling and analysis protocols. Also, no organic constituents were included in the monitoring of both the Baldivis and Kwinana (Waste Stream Management) landfills and petroleum hydrocarbons were only included in groundwater monitoring by seven respondents despite the widespread storage of diesel fuel. A notable omission from the routine analyses is chlorinated solvents such as PCE and TCE. However, there were only three reported instances of solvents being stored on sites. Such a limited level of use of solvents within the catchment of Cockburn Sound is unexpected. This may be a result of under-reporting, even though solvents were specifically mentioned in the request for information. It should be noted that the chemicals stored and used were only provided in detail in a few instances. In many cases, only the major chemicals or raw materials stored and used were identified, or had to be inferred.
The proximity of industrial premises within the Cockburn Sound catchment means that plumes of contaminated groundwater are likely to move onto neighbouring premises. This means that groundwater at any particular location may not only be contaminated by materials used on-site but may also be affected by other instances of groundwater contamination. A number of the monitoring schemes recognise this by included analytes other than those immediately associated with on-site activities. An example of this is the chlorophenols plume emanating from previous operations (CIK) at the current Nufarm Coogee site. Either routine or ad hoc analyses of groundwater for chlorophenols are undertaken by neighbouring businesses: BP Refinery Kwinana; CSBP; Tiwest Joint Venture; and Tyco Water. In a similar vein, Kwinana Cogeneration monitors petroleum hydrocarbons in groundwater to assess migration of contaminated groundwater from the adjacent BP Refinery Kwinana. Another important example is the inclusion of nitrogen species in the suite of analytes monitored at a number of sites. This is due to the recognised high incidence of regional and specific point sources of fertiliser and other nitrogen sources in the groundwater catchment. Eighteen of the respondents included at least one nitrogen species as part of routine groundwater monitoring. Only nine respondents could be considered as significant potential industrial sources of nitrogen. Sewage and waste water disposal at HMAS Stirling is a source of nitrogen in groundwater at Garden Island which discharges to Cockburn Sound. Although not investigated in detail, sewage disposal through septic systems is likely to be an issue worthy of attention in other industrial precincts around Cockburn Sound. A feature of the monitoring for nitrogen contamination was that even when included, the species monitored do not necessarily ensure that nitrogen contamination is identified or the total concentration of nitrogen determined. Eleven respondents determined total nitrogen while a further three measured both nitrate and ammonium (and not organic or other oxidised forms of nitrogen).
54 Status of Groundwater Quality in the Cockburn Sound Catchment
Company GW GW Contaminant GW used monitored identified managed Air Liquide WA (Henderson) No No No No Air Liquide WA Pty Ltd (Kwinana) No No No No Alcoa World Alumina Australia Yes Yes Yes Yes Aussie Organics Yes No No No Austal Ships No No No No Australian Fused Materials Pty Ltd No Yes No No Australian Railroad Group No No No No Baldivis Landfill Facility No Yes Yes No Bayer CropScience Yes No No No Beurteaux Yes Yes No No BOC Gases No No Yes No BP Refinery Kwinana Yes Yes Yes Yes Bradken Resources No No No No BulkWest Yes No† No No CBI Constructors Pty Ltd No No No No Chemeq No No† No Yes CIBA Specialty Chemicals Yes Yes No No Cockburn Cement Ltd Yes Yes Yes No Contract Marine Coatings No No No No Coogee Chemicals Yes Yes Yes No Cooperative Bulk Handling Yes No No No CSBP Yes Yes Yes Yes Delvex Industrial Cleaning No No No No DoD HMAS Stirling Yes Yes Yes No Doral Speciality Chemicals Yes Yes Yes No FlowTech Engineering No No No No Freo Machinery No No No No Henderson Landfill Yes Yes Yes No HIsmelt Corporation No Yes Yes No Image Marine (Austal) No No No No Key Group Engineering Yes No No No Kwinana Cogeneration No Yes Yes No Millennium Chemicals No No No No Nalco Australia Pty Ltd Yes Yes No No Northern Harbour Yes Yes Yes Yes Nufarm Coogee Pty Ltd No Yes Yes No Oceanfast Luxury Yachts (Austal) No No No No One Steel Market Mills No Yes No No Shinagawa Thermal Ceramics Aust Yes No No No Structural Marine No No No No Summit Fertilizers No Yes Yes No Tiwest Joint Venture No Yes Yes No Tyco Water Yes Yes No No United Farmers Cooperative Company No Yes Yes No United KG No No No No Waste Stream Management No Yes Yes No Wesfarmers LPG No No No No Western Power - Kwinana Power Station Yes Yes Yes Yes WestNetRail No No No No BHP Billiton - Kwinana Nickel Refinery Yes Yes Yes Yes † Groundwater monitoring planned
Table 3.6: Groundwater use, monitoring and management.
55
Company Aquifers Monitored Analytes Alcoa World Alumina Tamala Limestone, Safety Bay EC, pH, Alkalinity, Temp, NO3, NH4, TKN, Australia Sand NO2, Major Ions, Trace metals Australian Fused Ptotal, TDS, pH Materials Pty Ltd Baldivis Landfill Facility EC, pH, TDS, Major Ions, TN, NO3, NH4, TP, Trace metals Beurteaux TDS, Alkalinity, Hardness, HCO3, pH, FeTotal BP Refinery Kwinana Safety Bay Sand, Tamala Major Ions, Trace metals, TPH, BTEX, PAHs, Limestone, Rockingham Sand NO3, NH4, TKN, Ntotal, Ptotal, PO4, TDS CIBA Specialty Chemicals TPH, BTEX, TKN, COD, BOD, pH, EC, TDS, Acrylamide Cockburn Cement Ltd Tamala Limestone, Leederville TDS, EC, pH, Cl, Na, PCBs, Trace metals, Formation, Yarragadee NO3, NH4, Ptotal, Major Ions Coogee Chemicals TPH, Ptotal, Ntotal, TDS, EC, pH, Trace metals CSBP Safety Bay Sand, Tamala EC, pH, Ptotal, Ntotal, Trace metals, SO4, As, Limestone, Yarragadee Cl, F DoD HMAS Stirling Safety Bay Sand, Yarragadee Ntotal, NO3, NO2, TKN, EC, TDS, pH, TPH, BTEX Doral Speciality NH4, TDS, EC, pH Chemicals Henderson Landfill Spearwood Sands, Safety Bay EC, pH,TDS, Ntotal, NH3, Ptotal, Trace Sands, Tamala Limestone metals, TPH, BTEX, Major ions, Pesticides, TCE, PCE, PAH HIsmelt Corporation Pty Safety Bay Sand EC, pH, Major Ions, Trace metals, As, TPH, Ltd NO3, Ptotal, COD, TOC, FeTotal, Se Kwinana Cogeneration Safety Bay Sand TPH, BTEX, VHC, THM Nalco Australia Pty Ltd EC, TDS, pH, BOD, FeTotal Northern Harbour Tamala Limestone EC, NH4, NO3, pH, Major Ions Nufarm Coogee Pty Ltd Safety Bay Sand EC, Na, Cl, pH, Phenols, TOC One Steel Market Mills Ptotal, COD, pH, TDS, Trace metals Summit Fertilizers Ntotal, NO3, NH4, TKN, Ptotal, SO4, Trace metals, As Tiwest Joint Venture Safety Bay Sand EC, pH, Eh, Major Ions, Trace metals, Chlorophenols, Ntotal, NO3, NH4, TKN, Ptotal, PO4 Tyco Water TPH, As, Trace metals, PAHs, Semi-volatile Organics, Chlorophenols, pH, Phenols United Farmers Safety Bay Sand TKN, Ntotal, NO3, NO2, Ptotal, EC, pH, DO, Cooperative Company Temp Waste Stream EC, pH, TDS, Major Ions, NO3, NO2, NH4, Management TN, Trace metals Western Power - Kwinana Tamala Limestone TDS, SO4, NO3, Trace metals, EC, Alkalinity, Power Station Major Ions, FeTotal, TPH, BTEX BHP Billiton - Kwinana Safety Bay Sand, Tamala EC, pH, Major Ions, NH4, NO3, Ni, As Nickel Refinery Limestone
Table 3.7: Summary of groundwater monitoring undertaken.
56 Status of Groundwater Quality in the Cockburn Sound Catchment
3.3.3 SCREENING AND LOCATION OF MONITORING WELLS The general construction and screened intervals of monitoring wells is an important determinant of the effectiveness of groundwater monitoring networks both to identify the presence of contaminants and to quantify the transport and fate of contaminants in aquifers (see, e.g., Barber [1996], Davis et al. [1992]). For the Cockburn Sound catchment, this is particularly important because of the contrasting hydrogeological properties of aquifer sequences, and specifically the contrast between the Safety Bay Sand and Tamala Limestone facies of the Superficial Aquifer. There is also great potential for vertical stratification of contaminants within particular aquifer sequences. This is due to density contrasts between the in situ groundwater and contaminating fluids as well as the general stratification maintained by predominantly horizontal flow and low vertical dispersivities, often seen in some of these aquifer sequences (see, e.g., Davis et al. [1999]). The construction and screened intervals of monitoring bores varies considerably, even within the same monitoring network in some instances. This makes comparison of data within a monitoring network difficult and reduces confidence that contamination within the aquifer will be identified and fully quantified. There are cases where: • bores have relatively short screens near the water table, not sampling deeper in the superficial formation, potentially missing contamination from denser plumes or plumes emanating from greater distances up gradient; • bores with the top of the screen significantly below the water table, potentially missing localised contamination; and • even short screens at the top and the bottom of aquifer sequences that potentially poorly define depth distribution of contaminants over the whole aquifer sequence.
At least some monitoring schemes have multi-level monitoring bores with clusters screened at different elevations, mainly differentiating between the Safety Bay Sand and Tamala Limestone facies of the Superficial Aquifer and in rare instances, at two or three levels within the same facies. In some cases, monitoring bores are fully screened over the Superficial Aquifer in order to profile electrical conductivity over the full saturated depth of the Superficial Aquifer. However, multi-level monitoring to define detailed depth distributions of specific contaminants is not routinely undertaken, and apparently limited to rare, specific investigations. Groundwater sampling is sometimes undertaken from monitoring bores fully-screened over an aquifer sequence. While this provides evidence of contaminants in the aquifer, such sampling has limitations because of the hydraulics of sampling and variations in aquifer permeability which mask the distribution of contaminant concentration in the profile.
Expectedly, in the Cockburn Sound area, monitoring is concentrated within the Superficial Aquifer, and in the Safety Bay Sand in particular. Lack of monitoring in the underlying Tamala Limestone facies is notable, notwithstanding the presence of the basal clay that separates this facies from the Safety Bay Sand in parts of the catchment. Downward head gradients, either from natural recharge or induced by pumping, give rise to the potential for downward migration, especially for dense plumes of contaminants. Indeed, evidence for migration of contaminates across the basal clay into the Tamala Limestone is available. There are only three reported instances of monitoring deeper aquifer systems. Cockburn Cement and CSBP monitor the Yarragadee Formation as part of their groundwater abstraction from this aquifer. Cockburn Cement also monitors the Leederville Formation from which it also draws groundwater. BP Refinery Kwinana monitors the top of the Rockingham Sand Aquifer using two bores on their coastal boundary. It would seem that of these deeper monitoring efforts, the Rockingham Sand would have the greatest potential of the underlying sequences to be affected by contaminants in the Safety Bay Sand and Tamala Limestone aquifers.
57
The only other aquifer of interest is the Cockleshell Gully formation (Jurassic sediments) which continues to receive approximately 1.2 ML of wastewater from Nufarm Coogee every six months through deep well (>1000 m) injection, with licensed limits for phenoxy compounds, triazines, substituted ureas, molinate, trifuran and anionic surfactants. No monitoring of this aquifer was reported. Whilst the direct risks to Cockburn Sound from this deep plume are likely to be low, the deep well injection is not supported by precautionary monitoring programs and, since there is increasing interest in deep aquifer water supply for the Perth region it is appropriate to reassess this practice.
The areal placement of groundwater monitoring installations tends to reflect two primary objectives: firstly, to identify concentrations of contaminants moving onto the site and the concentration of contaminants leaving the site; and to identify and quantify particular on- site sources of contamination. With respect to the first of these objectives, some possible deficiencies seem evident in at least some of the monitoring schemes - more importantly for the off-site migration of contaminants. These deficiencies relate to placement of bores with respect to the prevailing hydraulic gradient, placement with respect to specific potential source areas, and lateral spacing with respect to likely plume dimensions from point sources. On the other hand, some schemes like those Alcoa has instituted around its tailings dams provide a spatial intensity that gives confidence that localised plumes will be detected. Further non-routine, spatially-intense sampling was reported by BP Refinery Kwinana and Alcoa along the beach of Cockburn Sound. These are also the only instances where monitoring has been done to more closely identify the discharge of contaminants to a receptor. In general, there is little evidence that the majority of the groundwater monitoring and assessment schemes are specifically aimed at determining fluxes of contaminants in the aquifer, other than at a rudimentary level, or support the evaluation of the ultimate fate of contaminants in the aquifer system and the effects on receptors. This is largely unsurprising since regulatory criteria for receiving water bodies like Cockburn Sound remain based on guideline concentrations of the chemicals of potential concern rather than the flux (or mass loading) of that chemical discharging into the Sound.
3.3.4 IDENTIFIED INCIDENCES OF GROUNDWATER CONTAMINATION The cases which may be inferred as evidence of contamination to groundwater are presented in Table 3.8. This includes the general classes of contaminants identified from the monitoring programs in place. These contaminants may not necessarily be solely a result of on-site sources and may include plumes from off-site sources. Nineteen respondents present instances of groundwater contamination although some of these are multiple instances at different premises or multiple plumes on the one site. In the six cases where some form of monitoring has been undertaken and contamination not positively identified, the monitoring would in most, but not all, instances seem inadequate to confirm the presence of contaminants in groundwater. This is both for materials used on site and for regional contaminants, specifically nitrogen. Inadequacy arises from both the number of bores being monitored, and the analytes monitored. In two cases, the information provided does not allow firm conclusions on the adequacy of the monitoring scheme to identify the presence of groundwater contamination. In the following discussion, concentrations will commonly be stated in units of mg/L (1 mg/L = 1000 μg/L).
The instances of groundwater contamination are all, with perhaps one exception, relatively long standing and well known within the Cockburn Sound catchment. The one possible exception is that for Doral Specialty Chemicals where ammonia concentration has shown a steady increase from 15 to 50 mg/L over the 4.5-year period of monitoring of a reticulation bore. Information currently at hand precludes further conclusions about the nature and source of the contamination. The identified incidence of contamination by
58 Status of Groundwater Quality in the Cockburn Sound Catchment
dissolved petroleum hydrocarbons on the premises of Kwinana Cogeneration is the only one that may be ranked as minor. It is possible that the lack of new plumes identified in our survey is a consequence of a (monitoring) focus on the management of known plumes, at the expense of monitoring efforts aimed at the discovery of unknown plumes.
In most instances, the contaminants identified are directly associated with individual on- site activities. However, the regionally-high background concentration of nitrogen was included as identified contamination by nutrients for Alcoa, Cockburn Cement, Coogee Chemicals, the northern boat harbour/Water Corporation and United Farmers Cooperative and Western Power. In the main, the nitrogen contamination in these cases comes from off-site sources. However, for the Northern Harbour/Water Corporation area the regional contribution of nutrients to the identified contamination is secondary. From present monitoring at the United Farmers Cooperative FPA lease site, it is difficult to determine the extent of on-going nutrient contamination to groundwater relative to regional background levels. There was evidence of appreciable nitrogen contamination (116 mg/L total N) to the top of the Safety Bay Sand aquifer associated with an on-site retention basin in May 2004. While total N reduced to 30 mg/L (May 2005), it is hard to decipher the source, particularly in relation to the up-gradient BHP Billiton Kwinana Nickel Refinery site mostly because monitoring bores are apparently only screened over a short interval across the water table. Also, it is unclear to what extent the nitrogen concentration in groundwater at Coogee Chemicals is contributed to by the site itself and other up-gradient sources. The nitrogen plume identified across the southern part of the BP Refinery Kwinana is also from off-site. The source was suggested as the former Kwinana Nitrogen Company. The chlorophenol plume from the former CIK site (now occupied by Nufarm Coogee) is the only other instance of groundwater contamination for the surveyed sites that is attributable to an off-site source. This chlorophenol contamination is included in responses from BP Refinery Kwinana, CSBP and TiWest. The inference from the response received from BOC Gases was that the chlorophenol plume also affects their site, but no monitoring data was provided to substantiate that inference.
3.3.5 GROUNDWATER MANAGEMENT Some form of active groundwater management to ameliorate the existing contamination of groundwater is undertaken by six of the respondents (Table 3.8), and additionally the authors are aware of the recovery efforts for the nutrient plume in the Northern Harbour precinct. In all but one case, this entails the recovery and treatment or disposal of contaminated groundwater. The primary purposes of these schemes are to reduce the amount of contaminants in groundwater and to contain the plumes of contaminants in the groundwater system. In at least some cases, these are specific requirements of licences to operate. In the other case, BP Refinery Kwinana undertakes in situ treatment of groundwater and recovers the source of the dissolved petroleum hydrocarbons.
On face value, the contaminated groundwater recovery systems are generally achieving the goals of either not increasing contaminant mass in the aquifer (as in the TDS from Western Power’s fly ash disposal at Perron Quarry), restricting further down-gradient migration of existing contaminant plumes (as in the caustic plumes from the Alcoa’s tailings facilities and the TDS from the shell sand stockpile at Cockburn Cement), and reducing contaminant mass (CSBP and BHP Billiton Kwinana Nickel Refinery – arsenic at the refinery and ammonium sulphate at the site of tailings). Some deficiencies of these schemes do appear though. Recent examples of off-site contamination from BHP Billiton Kwinana Nickel Refinery Baldivis tailings dams, caustic plume from Area F of Alcoa’s tailing disposal area and suspicion that high TDS groundwater from Western Power’s fly ash disposal at Perron Quarry is bypassing the abstraction bores indicate that issues of containing contaminated groundwater remain. Continued detailed evaluation of these schemes is required to ensure their effective performance.
59
Company GW Contamination Contaminants GW monitored identified managed Air Liquide WA No No No (Henderson) Air Liquide WA Pty Ltd No No No (Kwinana) Alcoa World Alumina Yes Yes Bases, TDS, Nutrients, Yes Australia Metals, Fluorides Austal Ships No No No Australian Fused Materials Yes No No Australian Railroad Group No No No Baldivis Landfill Yes Yes Bases, Nutrients, TDS, No Metals Bayer CropScience No No No Beurteaux Yes No No BOC Gases No Yes Undisclosed No BP Refinery Kwinana Yes Yes Petroleum Hydrocarbon Yes Liquids, Nutrients, Metals, Pesticides/herbicides BulkWest No No No CBI Constructors No No No Chemeq No No Undisclosed Yes CIBA Specialty Chemicals Yes No No Cockburn Cement Ltd Yes Yes TDS, Nutrients No Contract Marine Coatings No No No Coogee Chemicals Yes Yes Nutrients No CSBP Yes Yes Nutrients, Metals, Yes Pesticides/herbicides, Petroleum Hydrocarbon Liquids, TDS Delvex Industrial Cleaning No No No DoD HMAS Stirling Yes Yes Nutrients, Petroleum No Hydrocarbon Liquids Doral Speciality Yes Yes Nutrients No Chemicals Freo Machinery No No No Henderson Landfill Yes Yes Nutrients, Metals, No Petroleum Hydrocarbons HIsmelt Corporation Pty Yes Yes Nutrients No Ltd Key Group No No No Kwinana Cogeneration Yes Yes Petroleum Hydrocarbon No Liquids Nalco Australia Pty Ltd Yes No No Northern Harbour Yes Yes Nutrients Yes Nufarm Coogee Pty Ltd Yes Yes TDS, Pesticides/herbicides No One Steel Market Mills Yes No No Roche Castings No No No Shinagawa Thermal No No No Ceramics Aust Summit Fertilizers Yes Yes Nutrients, TDS No Tiwest Joint Venture Yes Yes Pesticides/herbicides, TDS, No Metals Tyco Water Yes No No United Farmers Yes Yes Nutrients No Cooperative Company United KG No No No Waste Stream Yes Yes Nutrients, TDS, Metals No Management Wesfarmers LPG No No No Western Power - Kwinana Yes Yes TDS, Nutrients Yes Power Station WestNetRail No No No BHP Billiton - Kwinana Yes Yes Nutrients, TDS, Metals Yes Nickel Refinery
Table 3.8: Identified contaminants in groundwater.
60 Status of Groundwater Quality in the Cockburn Sound Catchment
In undertaking management of contaminated groundwater through groundwater extraction, there is a need to consider the effects of groundwater abstraction on the environment (including indirect affects on groundwater quality), the resource as a whole and the availability of efficient and effective treatment, disposal or re-use. In at least some responses, it was indicated that the volume of abstraction was dictated by sometimes unrelated operational issues and particular abstraction rates may need to be reduced. The potential of continued abstraction may also be influenced by licence conditions that are derived from these other considerations.
Instituting groundwater abstraction schemes adjacent to the coastline also impose constraints due to the likely ingress of saline water into the aquifer. This has been manifest to some degree in all three groundwater abstraction systems that operate immediately adjacent to the coast – Northern Harbour, Alcoa and CSBP. This has the potential to affect the utility of the schemes. Alcoa presents an important case in point where increasing salinity of refinery production bores is an issue. Pumping from refinery recovery bores must be managed to reduce overall salinity and this may compromise the present control on the discharge of contaminated groundwater.
3.3.6 THREATS TO COCKBURN SOUND In evaluating the potential threat posed to Cockburn Sound by contaminants in groundwater the following classes of compounds are drawn from those identified in this review. These compound classes are: • Nitrogen species; • Petroleum hydrocarbons; • Metals; • Biocides (pesticides and herbicides); • Caustic solutions; and • Saline species (TDS)
Here, the potential threat by these compounds is evaluated according to a number of criteria, It should be stressed that their threat to the waters of Cockburn Sound differ from those posed to the groundwater systems themselves, the potential beneficial uses of groundwater and other receptors. Consideration of these additional threats is outside the scope of this assessment. Also, threats posed by other contaminants that have not been identified through the present evaluation of groundwater information are not considered here.
The criteria that are used to evaluate the threat posed by the contaminants include the inferred potential mass flux of contaminants, the distribution of the sources of the contaminants and the anticipated effects within Cockburn Sound. Without quantitative estimates of the mass fluxes of the contaminants at hand, the potential mass flux is inferred from: the source of the contaminants, particularly the location of the contaminants with respect to the ocean interface and what is known of the fate and transport within the aquifer system; and what is known of the discharge mechanisms to the water body in Cockburn Sound. For this reason, the threats posed are subjective and have not been evaluated with any quantitative analyse of the risks posed.
61 3.3.6.1 NITROGEN SPECIES Of the compound classes considered above, nitrogen contamination of groundwater would appear to pose the greatest threat to Cockburn Sound as a whole. The main factors contributing to this are the number of sources of nitrogen in the Cockburn Sound Management area, both point and diffuse sources, nitrogen contamination seems widespread and it has the potential to persist in the environment and ecosystems of Cockburn Sound. The other compound classes are more likely to be localised in their effects.
3.3.6.2 PETROLEUM HYDROCARBONS There were a small number of recorded instances of petroleum hydrocarbon contamination of groundwater. Despite this, and the great likelihood that there are more unrecorded instances of petroleum hydrocarbon contamination, they would seem to pose only a relatively low, localised threat to Cockburn Sound where the vector is groundwater. The reasons for drawing this conclusion are that because of their fate and transport in the groundwater, concentrations are reduced before entering the marine environment and once discharged to the waters of Cockburn Sound they are likely to be readily degraded to an innocuous form or volatilise to the atmosphere. The evidence that is available, although limited at a number of the sites, suggests that through natural attention, hydrocarbon plumes are relatively short. In these circumstances, to remain a threat to Cockburn Sound the source of petroleum hydrocarbons would need to be very close to the ocean. The best example can be drawn from the BP Refinery Kwinana. Even though there is a large, long-standing source close to ocean, the discharge of dissolved petroleum hydrocarbons is localised and the mass fluxes modest. One specific concern may be the nature of the petroleum hydrocarbons and that there may be some high molecular weight compounds that accumulate and/or enter the ecosystem. Again, the evidence presented suggested this may be localised.
3.3.6.3 TRACE METALS While there are some instances of trace metals, and arsenic in particular, as contaminants in groundwater, their generally limited mobility in aquifer systems would be expected to limit their flux into Cockburn Sound. Although, it should be noted that different metal species have differing mobility under a common geochemical regime. Unfortunately the monitoring information in this study does not provide any basis for identifying whether or not they are accumulating or are present in the sediments or biota at the aquifer/ocean interface. And sediment/biota sampling information is limited although that undertaken for Alcoa failed to identify groundwater as a source of contaminants. Overall, on the evidence to hand, metals would seem to pose a low risk to Cockburn Sound.
3.3.6.4 BIOCIDES Chlorophenols from the pesticide/herbicide plume at the former CIK site are the only pesticide/herbicide or derivative compounds that pose any identifiable threat to Cockburn Sound given the present information. The fate of these contaminants within the aquifer system is still being established through investigation and the possibility of them ultimately discharging to Cockburn Sound is indeterminate at this stage. Information is not sufficient to be definitive about the past mobility of the contaminants but they are present in the Tamala Limestone Aquifer and have migrated as far as the centre of the BP Refinery Kwinana. In any event, if this plume does reach the aquifer interface with Cockburn Sound, the effects are likely to be localised. These factors would again suggest that these contaminants pose a low threat to Cockburn Sound. However, this would need to be revised if more specific monitoring determined a wider distribution of such contaminants, or that it was shown to have a greater mobility and persistence within the aquifer systems. Of particular note is the lack of groundwater monitoring at other pesticide/herbicide manufacture and storage sites such as Bayer Crop Science.
62 Status of Groundwater Quality in the Cockburn Sound Catchment
3.3.6.5 CAUSTIC SOLUTIONS Caustic solutions currently have the potential to discharge to Cockburn Sound at Alcoa’s refinery. Monitoring bores show high-TDS and high-pH groundwater contaminated with dissolved metals and fluoride immediately west of the beach, while samples taken of shallow groundwater along the beach also showed high pH values. This groundwater may be discharging at the aquifer/ocean interface. Locally this may affect ecosystems associated with these sediments. The contact with saline ocean water may also tend to mitigate the elevated pH further reducing the threat to the waters of Cockburn Sound to a low level. However, geochemical modelling is required to determine the fate of the other contaminants.
3.3.6.6 SALINE SPECIES The high-TDS (separate from other specific contaminants) that is contaminating parts of the aquifers bordering Cockburn Sound inherently poses little risk to the already saline ocean waters. Perhaps the only conceivable effect may be if particular ecosystems are dependent on the discharge of low salinity groundwater through the bed sediments. The risk that the TDS concentration of groundwater at the point of discharge significantly affects these environmental conditions would appear low and any effects would likely be localised. Given the density of these high-TDS plumes, they may in-effect become part of the salt-water wedge as they approach the point of discharge.
3.3.7 LIMITATIONS OF THE SURVEY The review of the state of groundwater contamination presented here to assess the threat it poses to Cockburn Sound is limited due to a number of factors. These factors include time and other constraints determined by the original scope of the project as well as the availability of information and the current knowledge of the aquifer systems and how they interact with the waters of Cockburn Sound.
The availability of information and the amount of information able to be considered particularly related to the contamination of groundwater has itself been dictated by the original scope of the project through its specified time for completion. In this regard, the assessments presented here are based on responses received from the companies. By necessity, information is lacking where responses have not been received. Nevertheless, it is considered that the information presented in this Study is sufficient to provide a good general overview of the status of groundwater quality in the catchment and, through the industry and agency submissions, a clear picture of the kinds of point source contamination threats that need to be managed for the benefit of Cockburn Sound.
There are a number of particular operations, companies and agencies for which information was not received; information from these parties could assist in forming an appreciatively improved view of the state of groundwater contamination. Even so, the original reasons for selection of the individual sites, companies and agencies remain valid. Those with highest priority, given our current state of knowledge are given in Table 3.9. These were selected in terms of their proximity to Cockburn Sound, type and scale of operation and likely contamination of groundwater. They are grouped as being from the Australian Marine Complex at Henderson, and chemical manufacture and storage, mostly in the Kwinana area.
63 Grouping Company/Agency
Australian Marine Complex Australian Submarine Corporation Boat Spray Marine Interiors Pty Ltd SBF Shipbuilders Strategic Marine Pty Ltd Trailcraft Boats Tenix
Chemical manufacture and storage ELI Eco Logic Terminals West Pty Ltd Wesfarmers Kleenheat Gas Pty Ltd
Government LandCorp Water Corporation
Table 3.9: Premises with a high priority of future assessment.
No information was received from a range of ship and other marine construction premises in Henderson. This includes a number of operations on the ocean side of Cockburn Road where no information is currently available. The proximity to Cockburn Sound, with consequent reduced possibility of attenuation, together with what chemicals and other materials could be anticipated to be in use, highlight this locality as a priority for future assessment. LandCorp is responsible for several developments within the catchment, including the James Point Redevelopment, Hope Valley/Wattleup Redevelopment and the Australian Marine Complex. Missing information for LandCorp’s premises created significant gaps in the data set for this study, as did a lack of data for Water Corporation’s Kwinana operations. There also remain a number of relatively large-scale chemical manufacturing and storage operations for which we have no information.
There is a general lack of information on groundwater quality for that stretch of the coast between the Alcoa’s refinery and Russell Road in Henderson. This arises because the monitoring is opportunistic, relying on specific investigation at individual sites. Although locally the information may sometimes be spatially dense, there is no regional monitoring strategy currently in place. While Smith and Johnston [2003] considered the possibility of missing significant fluxes of nitrogen to be low given the current state of monitoring, this present gap in monitoring along this stretch of Cockburn Sound should be addressed. There is some evidence that provides impetus for this. Firstly, analyses from bores immediately upgradient of Lake Coogee were shown to have very high nitrogen concentrations. Intensive horticultural activities are likely sources of this nitrogen in groundwater. Similarly horticultural activities exist further to the south and would contribute to groundwater being discharged over the length of coast in question. There is some supporting evidence for elevated nitrogen concentrations in groundwater. This is from around Perron Quarry which is inland from the southern extreme of this area in question. Here, appreciably elevated nitrogen concentrations were noted in investigations at Western Power’s fly ash disposal site.
Otherwise the underlying limitation is in the data available. Particularly as there is a variable, and in many cases limited, suite of analytes available for interpretation and that sparse monitoring well networks do not ensure contaminants will be discovered. Also, the monitoring schemes tend to be reactive and it is possible that contaminants of emerging concern such as pharmaceuticals, personal care products and oestrogen-mimics have gone unnoticed. Even well-known contaminants such as chlorinated solvents are very poorly represented in the monitoring schemes.
64 Status of Groundwater Quality in the Cockburn Sound Catchment
4 Management Responses to Groundwater Quality
Groundwater supports many diverse ecological, industrial and community functions in the Cockburn Sound catchment. Managing the supply and quality of groundwater is a complex task, especially since the needs of different users are not always complementary and the replenishment of the groundwater resource is driven by uncertain climatic variations. Since the groundwater presents a net fluid input to Cockburn Sound, the quality of the groundwater is of prime importance to this study. Only by imposing suitable a suitable policy and management framework on groundwater quality can the environmental values of Cockburn Sound be sustained. Groundwater in the catchment moves generally toward the shore (or bed) of Cockburn Sound. The moving groundwater can carry with it contaminants picked up along its many trajectories toward the Sound. The contaminants can arise from natural and/or human (industrial, agricultural and urban) processes. It is of key importance to understand the sources of contamination, how they migrate with the groundwater and how they might impact Cockburn Sound. This Section discusses the regulatory and management framework presently in place for Cockburn Sound. As will be seen below, there is a comprehensive and structured hierarchy of conventions, agreements, legislation and policies that govern the environmental management function for the Cockburn Sound catchment and, hence, the Sound itself. These instruments represent management responses to environmental concerns at the international, national, state and local levels.
4.1 REGULATORY ENVIRONMENT
At the highest levels, human activities in the Cockburn Sound catchment are governed by Conventions and Agreements that Australia participates in, and by many Acts and Regulations of Federal and State Parliaments. In the context of environmental management, several major Acts and Regulations are particularly relevant. In the following, we summarise a few of the most pertinent international Conventions, Acts and Regulations ranging from international to local scope. These provide the essential conceptual and legal frameworks for the environmental management of Cockburn Sound. The following list is not meant to be comprehensive nor exhaustive – many other agreements and items of legislation overlap or impinge upon aspects of environmental management.
4.1.1 UNITED NATIONS CONVENTION ON BIOLOGICAL DIVERSITY 1993 The Convention on Biological Diversity came into force in 1993 and has been signed by over 100 nations, including Australia, but not USA. Despite the solid participation in the Convention, the UN Economic and Social Council noted [UNESC, 1997] that there were unfilled expectations, including “failure to integrate biodiversity into sectoral plans and national systems of accounts”, shortcomings in “rehabilitation and restoration of degraded ecosystems” and “lack of provision of incentives measures to protect biodiversity” at national levels. These assessments were made at a global scale, taking into account nations’ capacities for change. In 2001, the UNESC stated that the world faced a “global species extinctions crisis” brought about through human activities [UNESC, 2001]. Under the auspices of the various UN programs, various environmental classifications were brought into prominence, including the Red List of Threatened Species (compiled by the International Union for Conservation of Nature and Natural Resources – World Conservation Union (IUCN)), World Heritage Sites (UNESCO), Wetlands of International
65 Significance (from the 1971 Ramsar Convention on Wetlands) and Marine Protected Areas. Australia was a signatory to the Ramsar convention in 1975 and now has 64 Wetlands of International Significance listed. There are also 16 World Heritage sites and 14 Marine Protected Areas listed in Australia and its territories. This global framework is supported by Australian legislation at the Federal and State levels.
4.1.2 AUSTRALIAN GUIDELINES FOR ESTABLISHING THE NATIONAL RESERVES SYSTEM 1999 One particular outcome of Australia’s endorsement of the Convention on Biological Diversity has been the establishment of the National Reserves System under the Australian Guidelines for Establishing the National Reserves System [AGENRS, 1999], which selects protected areas in order to conserve biodiversity]. The Guidelines list the following six categories of protected areas as defined by IUCN:
Category I Strict Nature Reserve (a), Wilderness Area (b) Category II National Park Category III Natural Monument Category IV Habitat/Species Protected Area Category V Protected Landscape/Seascape Category VI Managed Resource Protected Areas
In order to be included in the national reserve system, an area must be able to be classified into the IUCN categories, and must be dedicated for the primary purpose of protection and maintenance of biological diversity. Other legal and managerial criteria also apply.
Regional Parks are areas of Regional Open Space identified under the Metropolitan Region Scheme, with legal standing vested in the Conservation Commission of WA, and managed through Department of Conservation and Land Management (CALM). There are two Regional Parks with elements inside the Cockburn Sound catchment. These are: • Beeliar Regional Park – totalling 34500 ha, including Thomson’s Lake Nature Reserve, The Spectacles and Lake Coogee • Rockingham Lakes Regional Park – including Lakes Richmond and Cooloongup. Planned land rezoning and urban development is unlikely to encroach directly on these parks.
4.1.3 NATIONAL ENVIRONMENT PROTECTION COUNCIL ACT 1994 The National Environment Protection Council Act 1994 [NEPCA, 1994] establishes the National Environment Protection Council (NEPC) with powers to make National Environment Protection Measures (NEPMs) that provide uniform goals, protocols, guidelines and standards for environmental management across Australia’s various jurisdictional boundaries. The NEPMs support a cooperative national approach to the environment. So far seven Measures have been made by NEPC, including a Measure for the National Pollutant Inventory (www.npi.gov.au) and a Measure for the Assessment of Contaminated Sites. The National Environment Protection Measures (Implementation) Act 1998 [NEPMIA, 1998] gives the Commonwealth powers to implement NEPMs on Commonwealth land and to Commonwealth activities. However, in States and Territories, the NEPCA allows each jurisdiction to choose how best to implement NEPMs, i.e. there is
66 Status of Groundwater Quality in the Cockburn Sound Catchment
no compulsion to implement the detail of each NEPM in a given State even though the State may be participating in the NEPM process. WA participated in the 1992 Intergovernmental Agreement on the Environment [IGAE, 1992] that led to the development of the NEPCA.
4.1.4 ENVIRONMENTAL PROTECTION AND BIODIVERSITY CONSERVATION ACT 1999 At a national level, the Environmental Protection and Biodiversity Conservation Act (1999) [EPBCA, 1999] protects biodiversity and streamlines environmental assessments and approvals through an integrated management approach. EPBCA enshrines the principle of ecologically sustainable development for initiatives with national or international environmental significance. Typical applications of EPBCA involve classifications of World Heritage properties (see whc.unesco.org) and wetlands of international importance (see www.ramsar.org), protection of National Parks and of Commonwealth marine areas (as defined under the United Nations Convention on the Law of the Sea [UNCLOS, 1982]), and listing of endangered and threatened species. The Australian Government Department of Environment and Heritage implements the EPBC legislation. There are presently only two World Heritage properties in WA, Shark Bay and Purnululu National Park. There are 12 Ramsar -listed wetlands of international importance in WA, two of which are located near or in the Cockburn Sound catchment. The Becher Point Wetlands (Ramsar Site No. 1048, 5/1/2001) south of Rockingham lie several kilometres outside the CSMC study boundary, while Thomson’s Lake, part of the Forrestdale and Thomson’s Lakes Ramsar wetlands (RAMSAR site No. 481, 7/6/1990), lies well within the CSMC boundary. These lakes are fresh to brackish and seasonal in nature and are surrounded by extensive urban and agricultural development. There are no current plans to list any other properties within Cockburn Sound catchment under the World Heritage or Ramsar classifications. There are presently two Commonwealth Marine Protected Areas in WA: the Mermaid Reef Marine National Nature Reserve and the Ningaloo Marine Park. Garden Island is a property of the Commonwealth and is managed under EPBCA, including all local DoD activities.
4.1.5 WA ENVIRONMENTAL PROTECTION ACT 1986 The WA Environmental Protection Act (1986) [EPA, 1986] applies to activities in WA that do not engender national or international environmental significance. There are several Parts of the Act that are invoked in the daily administration of the Act in Western Australia. Part II of the Act establishes the Environmental Protection Authority, and the Authority’s ability to publish draft environmental protection policies is defined in Part III. The Environmental Protection Authority is the peak environmental body in Western Australia, and is supported in its decisions by the WA Department of Environmental Protection. Its role is to assess proposals with ‘significant’ environmental impacts. The Environmental Protection Authority has the responsibility for environmental assessment of all Planning Schemes and Scheme Amendments. The Act also outlines the legal process for conducting environmental impact assessments (Part IV) and the regulation of activities that may cause environmental harm (Part V). Part VI of the Act deals with enforcement of policy and inspection of premises. Recently, the Department of Environmental Protection and the Water and Rivers Commission were restructured under the umbrella of the WA Department of Environment. At the time of this Study, the formation of a new WA Department of Water was underway – the new Department is likely to take over responsibility for water-related business from Department of Environment.
67 Administration of the Act is facilitated by the concept of prescribed premises, as defined in Schedule 1 of the Environmental Protection Regulations 1987 [EPR, 1987]. The prescribed premises categories provide numerical limits to commercial production or consumption across various industry sectors. Where companies exceed the stated limits at particular premises, the premises will fall under a prescribed category. For example, if a metal coating company uses more than 1000 litres of paint or powder coating per year it will be classed as Prescribed Premises Category Number 81. There are 89 Categories of prescribed premises listed in the Regulations. Under Part V of the Act, occupiers of prescribed premises may be required to observe environmental licence conditions, including regular environmental monitoring and reporting to DoE. Currently there are 83 licensed prescribed premises in the Cockburn Sound catchment (see Appendix 2) which are required to report regularly to DoE on environmental grounds. The Regulations also define a category of registered premises, a lesser category of prescribed premises which do not require licensing.
Companies that fall outside the prescribed premises definitions are still subject to Part V regulation, especially with respect to causing pollution and/or environmental harm. Part VI of the Act does provide far-ranging powers to the DoE to inspect premises to sample or monitor discharge of waste or other emissions. DoE usually relies on notifications of contraventions of the Act, either from the premises occupiers, from Local Government Authorities (LGAs) or from the community, for discovery of new emissions. Statistics on the administration of the Act across WA are provided by the DEP annual reports. For example, the 2003-2004 Annual Report [DEP, 2004] shows that 31% of licensed prescribed premises across WA (262 of 843) were inspected, with 66% found to be compliant with their licence conditions. For comparison, in 2002-2003 the figures were 36% of licensed prescribed premises were inspected (259 of 719), with 60% compliant with licence conditions. Over the last 5 years the number of inspections performed by DEP has declined from 425 in 1999-2000 to approximately 260 in 2002-2003 and in 2003-2004. The reason for this is not clear. It may be that premises have much better environmental practices, so with reduced potential for impacts and less need for inspection. It may also be due to limited resourcing or changed roles and obligations within the DEP. With increased development and changes in land uses across the Cockburn Sound catchment towards commercial/industrial the number of prescribed premises may grow. The level of pro-active inspection may need to be reviewed.
4.1.6 WA WATER ACTS Rights of access to groundwater supplies are established in the WA Rights in Water and Irrigation Act (1914) [RWIA, 1914], whilst the provision of water services to the WA community and related powers are vested in the Water Corporation through the WA Water Agencies (Powers) Act (1984) [WAPA, 1984], as transferred from the WA Water Authority by the Water Corporation Act (1995) [WCA, 1995] and the Water Agencies Restructure (Transitional and Consequential Provisions) Act (1995) [WARTCPA, 1995]. In principle, these Acts allow users to extract and use groundwater for residential or commercial purposes, subject to licensing conditions that may be applied in order to prevent the degradation of the groundwater resources or in order to maintain the water rights of other users. The focus of these Acts is to promote an orderly system for managing and allocating use of the groundwater resources. DoE provides groundwater abstraction licences to users under RWIA (1914). There is little mention in RWIA (1914) of issues of groundwater contamination arising from the use of groundwater – such issues are covered under EPA (1986).
68 Status of Groundwater Quality in the Cockburn Sound Catchment
4.1.7 WA CONTAMINATED SITES ACT 2003 The Contaminated Sites Act (2003) [CSA, 2003] was first tabled in WA Parliament in 2003 and has not yet come into full operation. Parts 2-10 of the Act are awaiting the passing of the Contaminated Sites Amendment Bill 2005 (which amends the Act in respect to off-site migration of contamination); the Bill is presently with the Legislative Council. The Act incorporates the “polluter pays” principle, ensuring that products are priced to cover full life cycle costs of production. Once in force, Part 2 of the Act will require individuals to report instances of site contamination. The DoE will also be required to maintain a public database of contaminated sites and surrounding information. Under Part 3 of the Act, owners or occupiers of contaminated sites will be held responsible for the remediation of the contamination and for the minimisation of waste and waste discharge. The concept of an “orphan site”, i.e. a contaminated site whose original owners/occupiers cannot be traced, is explicit in this Part of the Act. Parts 4 and 5 of the Act define the powers of DoE to issue investigation, clean up and abatement notices and to perform inspections and ensure compliance.
Once in effect the Act will provide a legislative framework for managing and remediating contaminated sites, providing much-needed support to the EPA in the area of assigning responsibility and enforcing compliance, especially for orphan sites.
4.1.8 WA ENVIRONMENTAL PROTECTION (UNAUTHORISED DISCHARGES) REGULATIONS 2004 The WA Environmental Protection (Unauthorised Discharges) Regulations (2004) [EPUDR, 2004] lists materials that must not be discharged into the environment through unauthorised business or commercial activity. Of particular interest here are the following materials listed in Schedule 1 of the Regulations: • Acid (pH < 4) • Alkali (pH > 10) • Animal waste • Animal oil, fat or grease • Compounds or solutions of cyanide, chromium, cadmium, lead, arsenic, mercury, nickel, zinc or copper • Degreaser • Detergent • Dust produced by a mechanical process including cutting, grinding, sawing, sanding or polishing a material • Dye • Engine coolant or engine corrosion inhibitor • Food waste • Laundry waste • Mineral oil • Organic solvent • Paint • Petrol, diesel or other hydrocarbon • Pesticide • Sediment • Sewage • Vegetable oil, fat or grease
All of these materials are used, stored or produced in the Cockburn Sound catchment. It is interesting to note that fertilizers and several classes of organic substances do not appear in this list.
69
Penalties for infringements of the Regulations are relatively low ($5000). The Regulations provide a useful alternative to pursuing offences under the Environmental Protection Act (1987), since under the Regulations infringements are simpler to assess and contain prescribed penalties. However, in some practical cases there can be confusion regarding classifications of particular substances under the above material types. Adoption of the Regulations is optional at the LGA level, and LGA officers must attend authorized training courses to interpret and apply the Regulations. Of the three LGAs in the Cockburn Sound catchment, Town of Kwinana and City of Rockingham already have officers authorized in the Regulations. City of Cockburn has not yet chosen to adopt the Regulations.
4.1.9 WA ENVIRONMENTAL PROTECTION (CONTROLLED WASTE) REGULATIONS 2004 The WA Environmental Protection (Controlled Waste) Regulations (2004) [EPCWR, 2004] govern the licensing of controlled waste carriers and the operation of controlled waste transportation and disposal activities at licensed waste treatment facility or depot. Schedule 1 of the Regulations lists 76 types of controlled waste, including halocarbons (PCB, PCN, PCT, PBB), tyres, pesticides, asbestos, fly ash, metals etc. DoE is responsible for managing controlled waste regulation and the operations of Waste Management (WA). Penalties for breaches of these regulations are also relatively low ($5000).
4.2 LAND PLANNING POLICY AND JURISDICTIONS Integrated land planning is critical if groundwater in the catchment is to be protected, and in turn in the long-term if the Sound’s environmental values are to be protected. It has been recognised that future land uses and activities within the catchment are likely to result in further groundwater contamination unless suitable controls are implemented through the land planning approval process.
There are several relevant land planning documents and jurisdictions. Each provides a check and balance on developmental pressures and activities within the Cockburn Sound catchment.
Land planning, policy and management documents and procedures span a range of scales and include: • The State Environmental (Cockburn Sound) Policy (SECSP) • The Environmental Management Plan for Cockburn Sound and its Catchment (EMP) • Local Planning Policy (LPP) • Statement of Planning Policy (SPP) • Development Approvals Processes • Town Planning Schemes • Town Planning Scheme Amendments
The land planning and policy responsibilities cover a wide range of jurisdictions including: • Cockburn Sound Management Council (CSMC) • Local Government Authorities (LGA which include The City of Cockburn, the Town of Kwinana and the City of Rockingham) • Environmental Protection Authority (EPA) • Western Australian Planning Commission (WAPC)
70 Status of Groundwater Quality in the Cockburn Sound Catchment
• Coastal Planning and Coordination Council (CPCC) • Western Australian Department of Health (DoH)
Below we give a brief description of some of the jurisdictions, and how they apply to the management of the environmental values of Cockburn Sound.
4.2.1 JURISDICTIONS
Because of the array of policy and planning instruments, it appears essential that each of the relevant jurisdictions are like-minded and have their decision making processes integrated to deliver positive outcomes for Cockburn Sound. CSMC is charged with the responsibility to consider how such integration may occur, without insisting that it must. Indeed, many of the agencies have a stated wish for greater integration and benefits to Cockburn Sound.
Local Government Authorities (LGAs) LGAs in the Cockburn Sound catchment include The City of Cockburn, the Town of Kwinana and the City of Rockingham. Principally, development control provisions rest with LGAs, however, the WAPC (see below) is responsible for development controls within the Hope Valley-Wattleup Redevelopment Area. LGAs have a statutory obligation to report to DoE incidences of environmental harm within their boundaries. LGAs must also report incidences of public health risk to Department of Health (DoH).
Implementation of the EPUDR (see Section 4.1.8) is uneven across the catchment. Only two of the three LGAs have officers qualified to apply the Regulations. This is due to a difference in philosophy across the LGAs, i.e. the “carrot” or the “stick”. However it would seem sensible for all LGAs to at least attain authorization to interpret and apply the Regulations, even if the Regulations were not strictly adhered to for every infringement.
Management by LGAs of environmental risks from new businesses is also uneven across the catchment. There is no comprehensive database of commercial premises and their operations across the catchment which, in turn, means that it is impossible to map the prevalence of chemicals and wastes across the catchment in any detail. This data gap represents an opportunity for integrated environmental planning between CSMC and the LGAs. It may be worthwhile to produce a one page questionnaire to be filled out by all new businesses seeking operating licences in the LGA areas. The aims of the questionnaire are: 1. that it would be easy to fill out, e.g. multiple choice format; 2. that it would promote environmental awareness among business proprietors; 3. that it would identify the approximate volumes of broad classes of chemicals and wastes (e.g. from EPUDR classifications) expected to be used or generated by each business; 4. that it would identify those businesses that had no provision for rainfall run-off interception or treatment at their premises.
71 The Environmental Protection Authority (EPA) The Environmental Protection Authority (EPA) is an independent statutory authority, and is the peak environmental body in Western Australia. It is supported in its role by the EPA Service Unit housed within the Department of Environment. Its role is to assess proposals with ‘significant’ environmental impacts. The EPA has the responsibility for environmental assessment of all Planning Schemes and Scheme Amendments.
Western Australian Department of Environment (DoE) The Western Australian Department of Environment (DoE) is the main integrated environmental protection and natural resource management agency in the State. DoE has significant environmental protection powers under the Environmental Protection Act. DoE came into being in 2004 after an amalgamation of the Department of Environmental Protection and the Water and Rivers Commission. The change in structure was prompted by a management review in 2003 [Carew-Hopkins, 2003] which identified cultural issues in some areas and under-resourcing in the environmental regulation function. The review also recommended the decentralization of regulation and management activities to the regions, including Cockburn Sound – Kwinana. At the same time, reviews by Welker Environmental Consultancy [WEC, 2003] and Robinson [2003] identified shortcomings in the licensing practices of the Department of Environmental Protection and in the maintenance of its enforcement role. With respect to the governing Act [EPA, 1986], the licensing role is described in Part V of the Act, and the enforcement role is described in Part VI of the Act.
Western Australian Planning Commission (WAPC) The Western Australian Planning Commission (WAPC) is the peak body responsible for land-use planning for urban, rural and regional areas of Western Australia. The WAPC makes and administers Regional Planning Schemes, all subdivision decisions, and assessment of amendments to Local Government Town Planning Schemes.
Coastal Planning and Coordination Council (WAPC) The Coastal Planning and Coordination Council (CPCC) was established under the WAPC in 2004 to advise the WAPC on matters relating to coastal planning and coordination throughout Western Australia. CPCC draws its membership from a range of state agencies, local government and the wider community. It is tasked with developing a metropolitan planning policy, due for implementation in 2006. DoE has a permanent delegate to CPCC.
Western Australian Department of Health (DoH) The mandate of the Western Australian Department of Health (DoH) is to promote, protect, maintain and restore the health of the people of Western Australia. In relation to Cockburn Sound marine waters, this relates to surface water quality that may come in contact with the population and in some way may lead to health impacts. Mechanisms for health impacts include direct human contact with the Sound (swimming, sailing, fishing), or through ingestion of food products harvested from the Sound. Examples of potentially harmful agents might include pathogens, algae biomass or toxic chemicals. Clearly in many matters related to environmental pollution the EPA, WA DoE and the WA DoH require integrated policy and coordination of activities.
Commonwealth Department of Environment and Heritage (DEH) The Department of Environment and Heritage develops and implements national policy and legislation to protect and conserve Australia’s natural environment and cultural
72 Status of Groundwater Quality in the Cockburn Sound Catchment
heritage. DEH’s major interest in Cockburn Sound is Garden Island, a Commonwealth property used by DoD. DoD activities must comply with the EPBCA (1999).
4.3 ENVIRONMENTAL CONDITIONS OF COCKBURN SOUND
4.3.1 ENVIRONMENTAL VALUES AND QUALITY OBJECTIVES A key platform of the environmental management strategy for Cockburn Sound is the identification of Environmental Values (EVs) and Environmental Quality Objectives (EQOs) for the Sound. As discussed in the Pressure-State-Response report [DAL, 2001], the Environmental Protection Authority (EPA) identified four EVs that were supported by six EQOs. After review and stakeholder submissions (e.g. Recfishwest [2002]), four EVs and a modified list of seven EQOs were ultimately adopted in the State Environmental (Cockburn Sound) Policy 2005 [GWA, 2005], as shown in Table 4.1:
Environmental Value Environmental Quality Objective
Ecosystem Health EQO 1. Maintenance of ecosystem integrity
Fishing and aquaculture EQO 2. Maintenance of seafood for human consumption
EQO 3. Maintenance of aquaculture
Recreation and aesthetics EQO 4. Maintenance of primary contact recreation values
EQO 5. Maintenance of secondary contact recreation values
EQO 6. Maintenance of aesthetic values
Industrial water supply EQO 7. Maintenance of industrial water supply values
Table 4.1: Environmental Values and Environmental Quality Objectives for Cockburn Sound.
The SECSP applies within the CSMC boundary defined in Figure 1.2.
4.3.2 ENVIRONMENTAL QUALITY GUIDELINES AND STANDARDS (EPA, 2005) The EV and EQO statements were developed by a consultative process between the State government and the public in the late 1990’s. Assessing whether the EQOs are being met is made easier by developing and applying Environmental Quality Criteria (EQCs), which rate quantifiable environmental properties against pre-determined environmental values. At the national level, environmental guidelines are based on the standards set by the National Water Quality Management Strategy (NWQMS) [ANZECC/ARMCANZ, 2000] and in response to National Environment Protection Measures (NEPMs) made by the National Environment Protection Council (NEPC).
73 SECSP specifies that the EQCs to be applied to the management of the Cockburn Sound protected area are those established in the Environmental Quality Criteria Reference Document for Cockburn Sound (2003-2004) [EQCRDCS, 2005]. The EQC classification supports two sub-types: environmental quality guidelines (EQGs) are thresholds which, if met, provide a high degree of certainty that the associated EQO has been achieved; whilst environmental quality standards (EQSs) are thresholds which indicate levels beyond which there is a significant risk that the EQO has not been achieved. Taken together, EQS thresholds for contaminants are likely to be less stringent than EQG thresholds.
4.3.3 TRIGGER VALUES (ANZECC/ARMCANZ, 2000) Rather than imposing a strict, single numerical level for each different water quality indicator, where quality measurements below the level are deemed acceptable and measurements above the level are deemed unacceptable, the approach is to specify conservative (low) “trigger” values or ranges. Exceedances of these trigger values in contaminated localities are deemed to indicate that further investigations are warranted. The quality guidelines distinguish between water uses, so that the guidelines for industrial water use may be different to the guidelines for recreational water use. For example, the recreational water quality guideline range for pH (a measure of acidity-alkalinity) is from 5.0 to 9.0. On the other hand, for slightly disturbed inshore marine ecosystems in south- west Australia the default pH range is 8.0-8.4; values outside this range are sufficient to trigger extra environmental investigations under the NWQMS framework. Table 4.2 provides a summary of NWQMS default trigger values applicable to seawater in Cockburn Sound. By contrast, the EQG values recommended under SECSP are much more complex, depending on which EQO is to be protected. The SECSP values are most stringent for EQO 1 (Maintenance of Ecosystem Integrity). A recent study [McAlpine et al., 2005] has supported the application of ANZECC/ARMCANZ [2000] trigger values for Cockburn Sound.
Stressor Trigger Value (summer/winter)
Chlorophyll a (μg L-1) 0.7/1.0
Total phosphorous (μg P L-1) 20/40
Filterable reactive phosphate (μg P L-1) 5/10
Total nitrogen (μg N L-1) 230/230
Oxides of nitrogen (μg N L-1) 5/5
Ammonium (μg N L-1) 5/5
Dissolved oxygen (% saturation) ≥90 (can vary diurnally and with depth)
pH 8.0-8.4
Table 4.2: Default trigger values for some physical and chemical stressors for slightly disturbed inshore marine ecosystems in south-west Australia [ANZECC/ARMCANZ, 2000].
74 Status of Groundwater Quality in the Cockburn Sound Catchment
Trigger values are also specified for freshwater lakes and reservoirs (see Table 4.3). The freshwater nitrogen and chlorophyll values are slightly higher than the corresponding marine trigger values, but the total phosphorus value is lower.
Stressor Trigger Value (summer/winter)
Chlorophyll a (μg L-1) 3-5/3-5
Total phosphorous (μg P L-1) 10/10
Filterable reactive phosphate (μg P L-1) 5/5
Total nitrogen (μg N L-1) 350/350
Oxides of nitrogen (μg N L-1) 10/10
Ammonium (μg N L-1) 10/10
Dissolved oxygen (% saturation) ≥90 (can vary diurnally and with depth)
pH 6.5-8.0
Table 4.3: Default trigger values for some physical and chemical stressors for slightly disturbed freshwater lake and reservoir ecosystems in south-west Australia [ANZECC/ARMCANZ, 2000].
National water quality guidelines are also specified for drinking water under the NWQMS [NHMRC, 2004]. These are based on scientific advice for the avoidance of adverse health affects in the human population. Where specific health impact information is lacking, or health risks are low, aesthetic or other criteria are used to fix the guideline levels. Typically, the drinking water guideline levels in Table 4.4 are more relaxed than the marine and freshwater ecosystem trigger values of Table 4.2 and 4.3.
Quality Indicator Guideline Level
Chlorophyll a (μg L-1) -
Total phosphorous -
-1 Nitrate (μg NO3 L ) 50000
-1 Nitrite (μg NO2 L ) 5000
-1 Ammonia (μg NH4 L ) 500 (aesthetic)
Dissolved oxygen (% saturation) ≥85 (aesthetic)
pH 6.5-8.5 (aesthetic)
Table 4.4: Drinking water guideline values for some water quality indicators [NHMRC, 2004].
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The topic of this report is groundwater quality as it impacts the Sound. Whilst greater consideration has been given to the science of marine and freshwater ecosystem health, and the human health impacts of drinking water quality variations, there is less understanding of intrinsic groundwater ecosystem response to groundwater contamination. In fact, the discovery of groundwater-dwelling organisms is itself relatively recent (see Hancock et al. [2005] for a useful historical summary), and this knowledge is not yet widely appreciated in the wider community. Consequently, most assessments of groundwater contamination are developed in terms of the effect of the contaminated groundwater on systems that receive the groundwater, i.e. groundwater receptors. Examples of receptors are agricultural foodstuffs that interact with irrigated groundwater, or surface water ecosystems, since groundwater often flows into lakes, rivers and oceans. For the purposes of this study, the prime groundwater receptor of interest is of course Cockburn Sound.
4.3.4 ASSESSING GROUNDWATER IMPACTS Assessing the potential impacts of groundwater contamination is performed by developing water quality guidelines based on the particular receptors involved. Draft guidelines have been developed by WA DoE [DoE, 2005] for contaminated site assessments. These guidelines, which list guideline levels for soil, sediment and water, are based on the NWQMS ecosystem health and drinking water guidelines mentioned above. That is, the drinking water guideline levels are used in groundwater investigations “… as a ‘first pass’ assessment of analytical results to determine if substances are present at a site at concentrations which may present a risk to either human health or the environment.” [DoE, 2003]. The disparity between the ecosystem trigger values (Tables 4.2 and 4.3) and the drinking water guideline levels (Table 4.3) is not as great as it may appear. Surface waters are affected by tidal cycles, wind forcing and rainfall, often causing complex mixing and circulation processes, and generally making the surface waters mobile and dynamic. On the other hand, groundwater is very slow-moving by comparison, even though it is affected by similar processes. The net effect is that groundwater-borne pollutants are normally diluted rapidly once they reach surface water bodies; dilution ratios may be of the order of 500:1 (surface water:groundwater). For a well-mixed surface water body, then, the net amount of contaminants in the surface water body as a whole may sometimes be more important than localized occurrences of high groundwater contamination.
Previous studies have shown that Cockburn Sound is not always well-mixed. Computer simulations of hydrodynamics in the Sound have shown that the mixing and circulation processes are promoted by the intermittent occurrence of storm events or strong seasonal winds. Even so, areas of the Sound have poor circulation (Mangles Bay, Northern Harbour), which are predicted to lead to the entrapment of contaminants and local deterioration in water quality. Built structures such as the Causeway and the harbour installations can also have significant impact on local dilution ratios and flushing rates [DALSE, 2002]. These predictions are supported by the available environmental data: the Northern Harbour has been prone to algal blooms in recent years, thought to be a consequence of a nitrogen plume in the groundwater exiting to the harbour through the local beach face [Parsons Brinckerhoff, 2005]. Contamination-induced effects on the Cockburn Sound ecosystem are not always so localised. Thirty years ago, after some hot summer weather accompanied by low winds, the combination of rising water temperature and high nutrient levels produced widespread algal blooms in the Sound (Figure 2.11).
76 Status of Groundwater Quality in the Cockburn Sound Catchment
4.4 ENVIRONMENTAL MANAGEMENT OF COCKBURN SOUND
Over the past five years, the EPA and CSMC have produced a set of environmental policy and planning documents for Cockburn Sound and its catchment. These documents provide for regular monitoring and reporting of environmental performance to government and the wider community.
4.4.1 POLICY, PLANNING AND MANAGEMENT DOCUMENTS
Environmental Protection (Cockburn Sound) Policy (EPP) The EPP was developed by EPA in draft form in 2002 to establish the environmental values, objectives and criteria for management of the Sound. The EPP draft provided the legal framework that allows or requires the Government to respond to the need to protect Cockburn Sound. It also required the preparation of an Environmental Management Plan. The EPP process was abandoned in favour of producing a State Environmental Policy for Cockburn Sound.
State Environmental (Cockburn Sound) Policy 2005 (SECSP) [Government of WA] This Policy, based on the earlier draft EPP, was developed by the EPA and released as a Government of Western Australia policy in 2005. It lists the EVs and EQOs for Cockburn Sound, and identifies the relevant EQCs as being those published in the Environmental Quality Criteria Reference Document for Cockburn Sound (2003-2004). The Policy provides for annual monitoring and reporting to CSMC by public authorities, and determines CSMC’s own reporting mechanisms. The CSMC is bound to prepare and implement an environmental management plan for Cockburn Sound, while relevant public authorities will act in concert with the objectives of the Policy. The Policy also outlines areas of High, Moderate and Low Ecological Protection within the body of the Sound.
Environmental Quality Criteria Reference Document for Cockburn Sound (2003- 2004) (EQCRDCS) [EPA] This document, developed by the EPA, states the EQC for Cockburn Sound and the general monitoring and assessment framework for the criteria. It is named explicitly in SECSP [2005] as the source of EQC for Cockburn Sound.
Manual of Standard Operating Procedures 2005 (MSOP) [EPA] This manual, developed by the EPA and released in 2005, describes monitoring and sampling principles for approximately 300 different physical and chemical variables relevant to the EQC for Cockburn Sound. The value of this document is that it describes the detailed methodologies to be employed when collecting and analysing the samples, thereby reducing the potential for systematic variations between differing sampling and analytical techniques.
Environmental Management Plan for Cockburn Sound and its Catchment (EMPCSC) [CSMC] The Interim Environmental Management Plan for Cockburn Sound and its Catchment (or EMP) was developed by CSMC and released in draft form in 2002. The EMP is the plan of action to deliver on the aims of the EPP. It has as one of its key objectives to “integrate planning and management of catchment land uses to minimise overall impact of ground and surface water contamination on environmental values of Cockburn Sound”. As such, it explicitly recognises the direct link between land uses in the Cockburn
77 catchment with water and ecological quality of the Sound. The final EMP was released in conjunction with SECSP in 2005.
4.4.2 MEMORANDUM OF UNDERSTANDING BETWEEN LGAS AND CSMC In August 2003, a Memorandum of Understanding was signed between LGAs in the Cockburn Sound catchment (The City of Cockburn, the Town of Kwinana and the City of Rockingham) and CSMC to ensure coordinated effort in the management of the catchment, and Sound.
Local Planning Policy for the Cockburn Sound Catchment (LPPCSC) The Local Planning Policy for the Cockburn Sound Catchment [LPPCSC, 2004] is a cooperative management response for the protection of Cockburn Sound. It links together the objectives of the EMP with State and Local Government to provide a consistent approach and decision making across the management horizons, especially related to local permissions for development that may impact the Sound. LPPCSC allows development control measures or conditions to be imposed so LGA can apply and respond to high-level policy. As part of LPPCSC, LGAs may consider special control areas. LPPCSC includes typical land-uses and specific controls that might be applied to manage and minimise nutrient and contamination issues associated with that land-use. LPPCSC also considers issues of vegetation management and rehabilitation, stormwater management, effluent disposal, buffer zones and development set-backs etc. So far, LGAs agree that LPPCSC has been a positive initiative and has led to greater integration in environmental management at various levels of government across the catchment.
It is clear that the opportunity to intervene, review or manage possible impacts on Cockburn Sound from land uses arises upon initial submission of applications to develop land, or when changes to land use are being proposed (or possibly even planned). One option for formalising input to the planning process is to establish a Statement of Planning Policy (SPP). This option was discussed in LPPCSC for Cockburn Sound, but was later discarded because much of the Cockburn Sound catchment was already covered under separate planning policies, e.g. for the Peel-Harvey catchment and for the Hope Valley- Wattleup Redevelopment Area. At a broader level, future proposals developed under the LPPCSC must be consistent with the planning requirements of the Coastal Planning and Coordination Council (CPCC). DoE is involved at both levels (LPPCSC and CPCC) which is appropriate for modern integrated planning, although there is at least some evidence that environmental issues are not always factored into the early stages of proposal development for the Sound.
5 Monitoring Groundwater Quality
5.1 WHOLE-OF-COMMUNITY INTERESTS In assessing the state of groundwater quality in the Cockburn Sound catchment, we are guided by the goal of protecting the environmental values of Cockburn Sound. At a system level, the Sound has the capacity to tolerate a certain level of contaminant insult. For larger contamination insults, the tolerance is exceeded and environmental impacts
78 Status of Groundwater Quality in the Cockburn Sound Catchment
may result. This can happen at specific locales within the Sound where contaminants may linger, e.g. at Northern Harbour where a groundwater nutrient plume discharges into a constructed embayment, or at the whole-of-Sound scale.
5.1.1 CATCHMENT SCALES If we consider the whole-of-Sound scale, the amount of contaminants able to be absorbed and tolerated by the ecosystem each year is large, probably well beyond the emission volumes of any of the individual industrial or urban stakeholders in the catchment. Nevertheless, the aggregate annual emissions of all stakeholders may potentially exceed the ecosystem tolerance level. In this way upholding the environmental values of the Sound is best addressed at a community level – all stakeholders have an interest in protecting the Sound.
The need for this kind of approach is best illustrated by the issue of eutrophication in the Sound. The previous section detailed several significant groundwater sources of nutrient input to the Sound originating from industrial or infrastructure activities near the coast. These sources are estimated to contribute approximately 234 ± 88 tonnes of nutrient (mainly nitrogen species) to the Sound each year. At the same time, the best evidence available suggests that approximately 17 tonnes is contributed by diffuse sources associated with different land uses further inland in the catchment. Both the calculations for diffuse and point source nutrient loadings are highly uncertain, but since the chlorophyll a levels in the Sound are still above guideline values, the conclusion is that the groundwater nutrient input remains too high (neglecting the potential for nutrient recycling in sediments on the sea bed).
One approach to reduce net nutrient inputs to the Sound is to reduce discharges at all known locations of point source nutrient contamination, i.e. various industrial and infrastructure sites. This may yield a better nutrient input result, but is unlikely to achieve the guideline levels for chlorophyll a in the Sound. A more comprehensive approach to the problem is required, involving more detailed and informed management of the point and diffuse nutrient sources in the catchment.
One step forward would be to re-institute regular monitoring of groundwater quality throughout the catchment. The resulting data, when combined with water quality data from the Jandakot Mound drinking water production bores and with monitoring data from licensed premises in the catchment, would provide a comprehensive picture of evolving groundwater quality issues in the catchment before the contaminated waters discharge to the Sound. It is particularly important to establish this monitoring regime before the major redevelopments planned for the catchment are complete and before the expected residential and population expansions occur. Since groundwater transit times from mid- catchment to the Sound are estimated to be of the order of decades, early identification of groundwater quality issues would give the opportunity to institute targeted “early bird” management responses at catchment, LGA and community levels potentially well before direct impact on Cockburn Sound actually occurs. This monitoring outcome would apply to all types of groundwater contamination, not just elevated nutrient levels.
It is envisaged that approximately thirty or forty bore locations would be sufficient to re- establish a catchment scale monitoring network. The locations could be arranged in three or four separate north-south lines, one near the eastern boundary of the catchment, one line near the coast, and one or two lines in between the two other lines. Each location should be screened near the water table. Sampling from these locations would be done on an annual basis, with a suite of water quality analytes similar to those tested at the Water Corporation Jandakot Mound production bores.
79 5.1.2 POINT SCALES Assessment of the impacts from point scale contaminations in the Cockburn Sound catchment is complicated by several factors. First, it is often difficult to detect narrow or localised plumes and, secondly, it is also difficult to quantify the contaminant flux of the plume, i.e. what mass of contaminant moves past a particular location per unit time. There should be more emphasis on determining fluxes of contaminants in the groundwater system rather than just documenting the mass of contaminant beneath premises in question. Flux measurements are important in the quantification of off-site emissions and the assessment of potential environmental impacts. Specialist hydrological methods are required to determine contaminant fluxes and to define accurately the size of contaminant plumes. These methods and remediation schemes should be aimed at ensuring groundwater quality objectives and evaluating effects on receptors.
Where groundwater contamination is detected it would be useful to classify the contamination according to the lithological formation in which it is present, i.e. Safety Bay Sand, Tamala Limestone, or similar. This immediately signals whether any consequent plume is likely to develop in zones characterized by preferential flows (Tamala Limestone) or by effective porous media (Darcy) flows. The type of flow regime is critical in designing subsequent plume investigation and/or remediation schemes. For example, monitoring bores spaced tens or hundreds of metres apart but relatively close to the source may not detect a contaminant plume moving rapidly through localised channel flows in the limestone formation. Fluxes of contaminants are often more important than absolute concentrations, since many receiving environments have an intrinsic capacity to absorb a certain level of insult per unit time, although it is recognised that regulatory criteria are based on concentrations not fluxes. For groundwater contaminant plumes, the flux is given by the product of the width of the plume by the velocity-weighted concentration. Hence it is important to measure the concentration, the plume width and the local groundwater velocity as functions of distance across the plume section. This is not such an onerous task for plumes residing in sandy aquifers, since the groundwater velocities are slowly varying functions of location and the plume contaminant flux may be able to be estimated from point measurements of head and concentration across the plume width. For the Tamala Limestone, a minimal approach is likely to engender significant error. The general uncertainty associated with the Tamala Limestone Formation is fundamental to all aspects of groundwater contamination in the Cockburn Sound catchment.
Because of the stratigraphic relationships between the sand and limestone formations in the catchment, the location of screened monitoring bore intervals in the profile is critical to the success of monitoring systems - no less so than the spatial distribution of bores themselves. The varying and inappropriately placed screened intervals made assessment of many monitoring schemes reviewed here extremely difficult and significantly reduced the worth of information collected. It is evident that licence conditions for some sites include rigorous stipulation of the location of the monitoring bores and the sampling regime. Such licence conditions should also stipulate screen lengths and placement. These should be adequate to characterise contamination over the vertical extent of the Superficial Aquifer and use multiple screens (not greater than 6 m in length, as the saturated thickness is adequately covered), placed in sympathy with the local hydrogeology. The uppermost screen should include the water table. Typical configurations may be two screens of 4 to 6-m length (depending on saturated thickness) in the Safety Bay Sand aquifer, one starting just above the water table and the other over the lower portion of the aquifer. Further screened wells should be considered for the Tamala Limestone, depending on the presence or absence of the basal clay. Screened intervals and locations of bores should be included with all reports.
Groundwater monitoring programs may evolve through several stages: • Sentinel monitoring to detect evidence of contamination;
80 Status of Groundwater Quality in the Cockburn Sound Catchment
• Detailed monitoring to characterise specific sources and instances of contamination on the premises; • Monitoring to determine the off-site fate and transport of the contaminants and estimates of mass fluxes in groundwater; and • Monitoring to validate and control remedial actions.
The construction and placement of monitoring wells may need to vary according to the purpose at hand. Sentinel monitoring should be designed to accommodate shallow and deep plumes and placement of bores needs to correlate with groundwater flow directions, likely sources of contamination and the likely width of plumes. The design should evaluate the likelihood of detecting plumes of varying extent.
Permanent groundwater monitoring along the beach in the near-shore zone may be needed for the ocean-front premises to detect and understand discharge processes. However, such monitoring needs to be carefully interpreted because of the dynamic nature of flow here due to the ocean boundary condition. There is a need to consider appropriate placement and methods of monitoring on the ocean front to estimate discharge fluxes reliably.
There are several sites with large quantities of stored chemicals that would be of concern if they contaminated groundwater with no groundwater monitoring in place. It is unclear what objective conditions prompt the licensed requirement to have groundwater monitoring. There is also a perception that as long as materials are stored according to regulations (e.g. bunded to contain spills) then no groundwater monitoring is required. This is not an appropriate perception as containment can fail and releases occur during storage, processing or disposal of wastes. Additionally, even competent bunding can be overtopped by spills larger than the bunded volume.
5.2 MAJOR POINT SOURCE RISKS TO COCKBURN SOUND
Making assessments of risk to Cockburn Sound is an important environmental management function that facilitates the prioritized application of limited resources. Focusing on the groundwater pathway, risk assessment must consider not only the size and scale of subterranean contamination, but also the potential mobility and reactivity of the contaminant species as well as its likely environmental impacts on the marine system should it ever arrive there. In order to make the risk assessment procedure clear, a simple risk weighting methodology was developed for this Study. The methodology is presented in Appendix A. The purpose of this methodology is to provide a clear, “first- pass” framework for ranking potential threats of groundwater contamination to Cockburn Sound. The methodology is not intended to be transferable to other ecosystems nor does it attempt to provide ecotoxological or human health dose risk estimates. Table 5.1 presents the thirteen highest assessed groundwater point source pollution risks to Cockburn Sound, based on the information provided voluntarily by companies and agencies for this study; these priority plumes are also shown by location in Figure 5.1.
We stress that this assessment depends on the data supplied voluntarily by industry. Not all companies and organisations approached for the survey supplied data to this study, and many other companies were not surveyed at all. The supplied data itself was of uneven quality, often rendering comparisons somewhat subjective. It is possible that other point source plumes exist and present threats to Cockburn Sound in addition to the thirteen plumes indicated in Figure 5.1. Other risks to groundwater quality in the
81 catchment are discussed in more detail in Appendix 1, including landfills, horticulture and sewerage disposal.
Distance to Plume Plume Location Sound1 Contaminant Monitoring Level Management (m) BHP Billiton KNR 970 N species, High Yes sulphates, metals CSBP 860 N species, metals High Yes Alcoa 290 N species, metals High Yes Water Corp Woodman Point 520 N species Medium Yes Love Starches/Nagata2 650 N species Medium Yes FPA/HIsmelt/LandCorp2 440 N species Low No Summit Fertilizers 1800 N species Low No BP Refinery 640 petroleum High Yes hydrocarbons DoD HMAS Stirling 620 N species Low No Doral Specialty Chemicals 860 N species Low No Coogee Chemicals 1280 N species Low No FPA – United Farmers 160 N species Low No CIK/Nufarm2 1970 chlorophenols Medium No 1 Approximate distance from the centre of premises lot to the nearest Cockburn Sound shore. 2 These plumes are historical and may pre-date the present occupiers of the premises.
Table 5.1: Priority plumes identified from data supplied by participating industries and agencies.
In the following subsections, summary comments are made regarding the priority plumes listed in Table 5.1.
5.2.1 BHP BILLITON/WMC KNR BHP Billiton Kwinana Nickel Refinery (formerly owned by WMC Resources) operations include the Baldivis Tailings Ponds/Lake Cooloongup and the Baldivis evaporation cell. Both the tailings ponds and evaporation cell lie immediately outside the Cockburn Sound Management Catchment. However, contaminant plumes from both may have the potential to migrate into the CSMC area and were evaluated for this reason. The major concern for contamination of groundwater, and effect on Cockburn Sound is the ammonium sulphate which is used in the refinery process and entrained in the tailings that have been disposed in residue ponds. Ammonium sulphate contaminant plumes have been identified in groundwater at the Kwinana Nickel refinery and Baldivis tailings ponds. Other instances of contamination have arisen from leaks in the effluent pipeline to the Baldivis operations. An arsenic plume has also been identified at the Kwinana refinery site. At the Baldivis tailings ponds monitoring is conducted in 105 individual bores. Many of these are shallow and deep pairs at the one location while others are screened over the entire saturated thickness of the Superficial Aquifer. Groundwater management around the tailings ponds is through recovery of contaminated groundwater. Six dual- pump recovery system bores were operated in the tailings pond area.
82 Status of Groundwater Quality in the Cockburn Sound Catchment
Figure 5.1. Highest priority plumes from point source contaminations, identified from data supplied by participating industries and agencies.
83
Under these current management practices, there appears to be little risk that this contamination will have an impact on waters of Cockburn Sound. Similarly, responses to known leaks in the effluent pipe are also likely to remove risk of any effect of Cockburn Sound.
The evidence so far is that there has been no significant leakage of high salinity (sodium chloride) water from the lined evaporation cell and would not in any event be expected to pose a threat to Cockburn Sound. The groundwater monitoring system at the Kwinana refinery is mainly focussed on determining the mass of the known ammonium sulphate contaminant (although nitrate is also very high) in the groundwater system and determining sources of that contamination. However the arsenic contamination was discovered as part of this monitoring program and arsenic monitoring is now included more routinely. Less attention has been given to estimating off-site fluxes of the contaminants. There is gross contamination of the groundwater by both ammonium and nitrate. Recent measurements (2003) show ammonium concentrations as high as 1800 mg/L and nitrate concentrations as high as 900 mg/L.
Monitoring at the refinery is relatively extensive with 82 individual bores with groundwater quality results. A proportion of these are shallow and deep pairs with resultant monitoring at around 66 locations. The vertical sampling seems predominantly in the lower portion of the Safety Bay Sand aquifer and over most of the thickness of the Tamala Limestone aquifer. Down-hole profiling of electrical conductivity is undertaken in some of the longer- screened bores to identify vertical distribution of the contaminants. A series of production wells recover ammonium sulphate-contaminated groundwater at the refinery site. The operators have all but ceased the recovery pumping due to the reduction in the amount of contaminant remaining as compared to previous levels. A production bore at the refinery recovers arsenic-contaminated groundwater.
5.2.2 CSBP The 800-m wide western boundary of the CSBP site is located within 60 m of the ocean in the south-western part of Cockburn Sound. The operations at the site produce fertilisers and sources of nutrients in the form of ammonium sulphate and di-ammonium phosphate. Appreciable volumes of diesel fuel are also stored on site in above-ground and below-ground storage tanks. These operations have contributed to three distinguishable contaminant plumes in groundwater – an ammonia/arsenic plume, an ammonium sulphate (AMSUL) plume and a petroleum hydrocarbon plume. As well as the plumes generated from on-site activities, the CSBP site is also affected by the plume of chlorophenol-contaminated groundwater emanating from the former Chemical Industries Kwinana site now occupied by Nufarm.
There have been intensive hydrogeological investigations on the site to delineate the extent of contaminants in the underlying aquifer and to understand the characteristics and connection of the aquifer sequences. Continuing, routine monitoring of groundwater quality is reasonably intense, incorporating 24 monitoring bores, five comprising dual screens, with three- and six-monthly monitoring of differing suites of inorganic constituents. Groundwater quality from 12 production and irrigation bores has also been routinely monitored, some at even higher frequency. Organic contaminants have not been included in routine monitoring. However this is proposed following the identification of petroleum hydrocarbon contamination over part of the site. Many other monitoring bores exist over the site from past and continuing investigations. There is potential to increase the intensity for routine as well as specifically-targeted investigations – for instance in determining mass fluxes of contaminants towards Cockburn Sound. Such a study was reported in 2002 which, through careful determination of groundwater flow directions and gradients, refined estimates of the mass flux of nitrogen towards Cockburn
84 Status of Groundwater Quality in the Cockburn Sound Catchment
Sound. Indeed, nitrogen-contaminated groundwater is inferred to extend all the way to the coast in both the Safety Bay Sand and Tamala Limestone aquifers (total N in the range 100 – 200 mg/L observed in the Tamala Limestone aquifer on the western boundary of the site) and N-contaminated groundwater also discharges into the southern part of the BP Refinery.
It appears that better estimates of the flux of contaminants (specifically nitrogen) to Cockburn Sound may be gained by including 12 new (2004) beachfront bores and applying more emphasis to defining the vertical distribution of contaminants as part of monitoring schemes. This would also need to be linked with furthering the understanding of discharge of contaminated groundwater in the Tamala Limestone aquifer to Cockburn Sound. There is proposed management of the combined ammonium/arsenic contamination through the extraction and treatment of the contaminated groundwater which has been successfully trialled at the site.
5.2.3 ALCOA Alcoa’s Kwinana refinery operations have led to contamination of groundwater by caustic solutions underneath the refinery itself as well as under the residue tailings ponds. In addition to the caustic solution, high nitrogen, metals and fluoride concentrations are also encountered in the groundwater beneath the refinery, within 100 m of Cockburn Sound. Alcoa has a very comprehensive monitoring program aimed primarily at identifying the high salinity and high pH caustic solutions. In this program Alcoa routinely monitors 481 monitoring bores, recovery and production bores to provide a regional as well as site- specific picture of contamination in the aquifer. The main technique is down-hole logging in fully-screened wells to determine vertical profiles of pH and electrical conductivity (as a measure of salinity) in both the Safety Bay Sand and Tamala Limestone aquifer. However, there are also annual comprehensive analyses of groundwater from 19 abstraction bores at the refinery. Through these on-going monitoring efforts and a number of specific investigations the hydrogeology of the affected parts of the Superficial Aquifer are well understood – except perhaps the processes of groundwater discharge in the near-shore environment.
Groundwater management is instituted through pumping to recover the contaminated groundwater and prevent further migration of contaminants in the aquifer. In this regard, the recovery at the separate tailings residue facilities appear to have contained the plumes of contaminated groundwater (although not all issues of leakage are resolved) and potentially could be adapted for contingencies of increased or new leakage of contaminants to groundwater. Hence, under the current management schemes, the residue tailings facilities appear to pose little risk to Cockburn Sound.
The situation at the Refinery itself is more complex, because of its proximity to Cockburn Sound and constraints on the recovery of groundwater for controlling the discharge of contaminated groundwater to the ocean environment. A key factor is the increasing salinity of refinery production bores from the ingress of seawater into the aquifer and that pumping from refinery recovery bores is being managed to reduce overall salinity. This may limit the control that may be exercised on the discharge of contaminated groundwater. Even at present, there is little direct evidence of the extent to which the flux of contaminated groundwater to Cockburn Sound is being restricted by the groundwater recovery scheme. No permanent monitoring installations are in place on the ocean side of the ocean-front recovery wells. Indeed, highly-contaminated groundwater (October 2004) was detected in beach-front abstraction bores along 600 m of the western refinery boundary. These contaminations included concentrations of: total Kjeldahl nitrogen (TKN) ranging from 15 to 59 mg/L; total phosphorus up to 26 mg/L; aluminium up to 44 mg/L and fluoride up to 67 mg/L. These bores are 50 to 100 m from the ocean. Information from a 2003 survey of shallow groundwater along the beach indicated some possible
85 evidence of contaminated groundwater in the discharge zone to the ocean. This suggests better understanding is required of the fate of the contaminated groundwater in the presence of such groundwater recovery schemes. As is the case along other parts of the coastline, the detail of discharge of contaminated groundwater from the Tamala Limestone aquifer also needs to be better understood. In this particular instance the geochemistry of the interactions between the high-pH contaminated groundwater and seawater in the discharge zones also needs to be further evaluated to assess the ultimate impact of the contaminants on Cockburn Sound.
5.2.4 WATER CORPORATION – NORTHERN HARBOUR/WOODMAN POINT The site of the sludge drying beds of Water Corporation’s wastewater treatment plant at Henderson is a continuing source of nitrogen in groundwater discharging to the Northern Harbour (Jervoise Bay). The site of the former sludge beds is approximately 800 m from the present shoreline of Cockburn Sound. Concentrations of nitrogen in the form of nitrate and ammonium are monitored in two extraction bores adjacent to Cockburn Road recovering contaminated groundwater, 11 coastal groundwater bores covering an area down-gradient of the site of the drying beds to Cockburn Road and eight monitoring bores inland of the drying beds, east of Lake Coogee. Some of the coastal bores are screened at different depths (forming monitoring nests) while some of the inland monitoring bores are multi-levels, with a number of different screens in the same hole.
Routine sampling for nitrate and ammonium together with major ions is undertaken in most bores on a six-monthly basis, while monthly analyses for the two nitrogen species and EC are undertaken for the production bores. From this monitoring, the plume appears about 500 m wide as it crosses underneath Cockburn Road. No monitoring is undertaken between the groundwater extraction bores and the water body of the Northern Boat Harbour to confirm the detail of the discharge of the nitrogen-contaminated groundwater to the boat harbour. Over the past five years, nitrogen concentrations have remained around the same levels, except for increased concentration in 2003 following the removal of surface material from the drying beds. There has also been a trend for more of the oxidised form (nitrate) of nitrogen in groundwater following the removal of the surface material from the drying beds. Concentrations of nitrogen in March 2005 were of the order 50 mg/L for the sum of that in the form of nitrate and ammonium.
Management of the nitrogen-contaminated plume is via groundwater extraction aimed at reducing the flux of nitrogen to Cockburn Sound. However, recent estimates of the efficiency of this extraction scheme, combined with that for the Love Starches’ plume (see below), reduces the flux of nitrogen to the Northern Harbour by only 23%. Incomplete capture of the plume is confirmed by continuing high nitrogen concentrations south of the southern extraction bore. Better depth definition of the plume, and monitoring between the extraction bores and the harbour would give a clearer picture of the continuing nitrogen flux and detail of the discharge mechanisms to the water body itself.
5.2.5 NAGATA (FORMER LOVE STARCHES SITE) An ammonium plume in groundwater emanates from the former Love Starches site now occupied by Nagata. This plume is a legacy of the disposal of wastes directly to the aquifer under the site which is 600 m from the current shoreline of the Northern Boat Harbour. This plume is immediately to the south of that from the Water Corporation’s former sludge drying beds. The details provided for this study consisted of that current (March 2005) monitoring (seven monitoring and two production bores) of the Northern Harbour groundwater extraction scheme which is entirely down gradient of the site itself along with some limited data from nearer the source.
86 Status of Groundwater Quality in the Cockburn Sound Catchment
No information was provided by Nagata on groundwater monitoring in and nearer the source. The groundwater sampling scheme consists of nitrate, ammonium and major ions determinations at six-monthly intervals while monthly analyses for the two nitrogen species and EC are undertaken for the two production bores. Again there is no monitoring over the 150 m distance between the extraction bores and the harbour itself. The plume is indicated as being at least 120 m wide at Cockburn Road. The nitrogen contamination is predominantly in the form of ammonium (note that no determinations of total or organic nitrogen are included in the current monitoring routine).
Recent trends suggest nitrogen concentrations in the two extraction bores used to intercept the plume are decreasing over time. However, monitoring bores upgradient show little if any or appreciably smaller reductions over time. Further detailed analyses of fluxes within the aquifer are needed to confirm that the reduced flux from the extraction bores reflects reduced fluxes in the aquifer as well as confirming the rate at which the flux may be reducing.
5.2.6 FPA/HISMELT/LANDCORP Groundwater on the HIsmelt site shows some high levels of contamination by nitrates that do not appear linked to current activities at the site (Fremantle Port Authority and LandCorp presently occupy or manage neighbouring properties). However, it is noted that an on-site containment pond does show elevated concentrations of nitrate (8 mg/L). Maximum concentrations in groundwater were more than an order of magnitude greater than this (120 mg/L, May/June 2005). Although this maximum value is relatively isolated in the southern part of the site, 11 of the 15 bores which were being monitored quarterly had nitrate concentrations of 20 mg/L or greater. Most of these other elevated concentrations occur on the eastern part of the site. Unfortunately, the present monitoring does not enable the source and fate of the observed nitrate to be clearly identified.
The 15 bores used for routine monitoring are fairly widely spaced; nitrate is the only nitrogen species measured and, from other information at hand, the bores are screened over a relatively short interval near the water table. Thus, the information to hand does not reveal a full picture of the nitrogen distribution within the Superficial Aquifer. There is also some uncertainty about directions of groundwater flow, with an appreciable northerly component of flow and localised mounding on the site indicated by water table contours. This may partially explain relatively low nitrate concentrations in bores along the southernmost 450 m of the western boundary of the site which is 500 m from the ocean. Despite this, the magnitude of the nitrate concentrations and the distance over which they are observed suggests an appreciable flux of nitrogen moving in groundwater towards Cockburn Sound.
5.2.7 SUMMIT FERTILIZERS Nitrogen contamination of groundwater at the Summit Fertilizer site has arisen from the bulk movement of fertilizer and the subsequent discharge of contaminated runoff from hardstand at the site. This runoff, together with roof runoff is channelled to two drainage basins lined with a mixture of gypsum and red mud. While the lining affords some removal of phosphate before reaching groundwater, groundwater samples show it is limited in its effectiveness in removing nitrogen. Concentrations near the basins range up to hundreds of mg/L total nitrogen. However, the groundwater monitoring does not enable the delineation of the spatial extent of the nitrogen plume in groundwater, specifically the distance it extends towards Cockburn Sound which is of the order of 1800 m from the site. Only four groundwater bores and two reticulation bores are monitored. The magnitude of the nitrogen concentrations in groundwater make it a potentially important source of nitrogen input to Cockburn Sound.
87 5.2.8 BP REFINERY KWINANA The BP Refinery Kwinana has a long history of petroleum hydrocarbon spills into the Superficial Aquifer which has produced contamination of the aquifer by the petroleum liquids themselves as well as dissolved petroleum hydrocarbons in the groundwater. Other contaminants resulting from on-site activities have not been identified. Significant manganese concentrations have been identified but are thought to represent natural background levels. Copper has also been identified as a possible contaminant. Otherwise, elevated arsenic concentrations on the northern part of the site do not have an identified source and are being investigated further. Because of the refinery’s location, at least three contaminant plumes pass onto the site from other sources. These include an ammonium plume from CSBP, an arsenic plume suspected to be from the former Kwinana Nitrogen Company and chlorophenols from the former CIK site.
Routine monitoring is focussed on both dissolved contaminants and the petroleum hydrocarbon liquids. One hundred and fifty seven bores screened across the water table monitor thickness of hydrocarbon liquids and movement towards the coast. Along the coast, 20 bores at seven locations monitor the quality of groundwater discharging to Cockburn Sound in the Safety Bay Sand, Tamala Limestone and Rockingham Sand aquifers. These are sampled annually. A further 37 bores monitor groundwater at another 20 locations along the eastern boundary and in the middle of the refinery. One-off sampling of shallow groundwater along the 2.65-km beachfront at 20- to 100-m spacing has also been undertaken to better define individual contaminant plumes. Other specific studies of the hydrogeology and contaminant concentrations have been undertaken.
Dissolved contaminant fluxes to Cockburn Sound are low, and trends are generally down or steady. Surprisingly little dissolved hydrocarbons are seen at the coast, providing some evidence of significant natural attenuation of the contaminants at the ocean- groundwater interface. Copper concentrations have also reduced. Nevertheless, the location of the refinery on the ocean front, with storage and process units as close as 150 m to the shoreline, raises the importance of the site in terms of impacts to Cockburn Sound. Evidence of increasing mass flux in some plumes is also of note. Groundwater management has included petroleum hydrocarbon liquid recovery, including dual-phase groundwater recovery as well as in situ groundwater treatment using air sparging to stop the off-site migration of dissolved petroleum hydrocarbons. The in situ groundwater treatment includes a section of the coastal strip.
5.2.9 DOD - HMAS STIRLING Groundwater contamination at the Department of Defence’s HMAS Stirling facility has arisen from a number of known chemical spill incidences as well as leakage and disposal from the facility’s sewage and wastewater treatment systems. Incidences of uncontrolled leaks and spills of diesel fuel, white spirits have created local plumes of petroleum hydrocarbons and other organic chemical plumes at the fuel storage facilities near the port areas, torpedo maintenance facility and fuel storage facilities. High nitrogen concentrations (up to 240 mg/L total nitrogen) have been associated with leakage of effluent from treatment and disposal ponds in the centre of Garden Island. Some higher than expected nitrogen concentrations in a range of bores has lead to speculation of a range of sources other than the sewage treatment systems. However, a plume of nitrogen-rich groundwater from the wastewater disposal area is estimated to be flowing southeast to Cockburn Sound. From one shallow and deep pair of bores, the plume appears to be limited to the upper part of the aquifer.
Because of the geographical spread of facilities around Garden Island, a number of groundwater monitoring schemes are in place. These include 17 bores associated with the sewage treatment system; six bores around four separate fuel facilities; and four bores around the torpedo maintenance facility monitored for white spirits. Monitoring is
88 Status of Groundwater Quality in the Cockburn Sound Catchment
conducted quarterly (one torpedo maintenance facility bore is monitored monthly) and includes relevant nitrogen species and petroleum hydrocarbon analyses. Other investigation and monitoring bores have been installed for other specific purposes, including five bores installed around a recent diesel spill at the Powerhouse, monitored monthly.
Although close to the marine environment of Cockburn Sound, the petroleum hydrocarbon and white spirit contamination of groundwater are not considered priority plumes for their possible effect on Cockburn Sound, primarily because of the biodegradability of the hydrocarbons. Of more importance is the probable discharge of nitrogen-rich groundwater in the vicinity of seagrass beds on the eastern side of Garden Island. Beach-front bores have indicative total nitrogen concentrations up to 26 mg/L.
No groundwater management is being undertaken to reduce the flux of nitrogen towards Cockburn Sound, although the bitumen-lined ponds associated with the sewerage treatment plant are programmed to be re-lined in 2006/07. Further monitoring and investigation is required to determine the discharge fluxes of nitrogen in groundwater and where the contaminated groundwater is discharging to the marine environment. This is being addressed by an extended bore monitoring program and a new research effort on the uptake of groundwater nutrient discharges by seagrasses.
5.2.10 DORAL SPECIALTY CHEMICALS Doral Specialty Chemicals is a chemicals manufacturer located some 800 m from the Sound. Anhydrous ammonia is used in the production process along with inorganic acids. Recent monitoring has shown an increasing trend in ammonium concentration in a reticulation bore to 50 mg/L over the 4.5-year period of monitoring. This suggests the possibility of releases of ammonia to the groundwater system. Other monitoring consists of monthly analyses of groundwater from four monitoring bores. The analyses include ammonium and no other nitrogen species. There were similar increasing trends in ammonium concentration in one other monitoring bore but at lower concentration.
More detailed evaluation of the information at hand (including supporting data on bore location and screen depths not provided as part of this review) along with further monitoring bores, and analyses of the suite of nitrogen species would be required to better define the source and extent of nitrogen contamination as well as the flux of nitrogen towards Cockburn Sound. No indications of any groundwater management were supplied to this study.
5.2.11 COOGEE CHEMICALS Monitoring at the Coogee Chemicals site has indicated total nitrogen concentration of up to 29 mg/L, suggesting a nutrient plume of some significance. The monitoring (six bores) at hand does not allow an assessment of the source of this nitrogen and indeed whether or not it is from an on-site source such as the boiler blowdown pit. Nitrogen concentrations in the water in this pit are generally much lower than those observed in groundwater – the maximum observed total nitrogen has been 4.3 mg/L. Another six monitoring bores which have not been used for nutrient or other inorganic/organic analyses and two productions bores could also be used to define the nutrient plume. This would enable a better assessment of the risk posed to Cockburn Sound.
It is noted that the Coogee Chemicals site is located about 1.3 km from Cockburn Sound. No specific groundwater management schemes were identified in the response for this report. However, indications of two production bores at the site would suggest that such
89 groundwater extraction would exert some effects of the nitrogen plume, depending on its location.
5.2.12 FPA - UNITED FARMERS COOPERATIVE LEASE The United Farmers Cooperative leases FPA land adjacent to the Kwinana Bulk Jetty for the storage of fertilisers. The western boundary of the site is within 50 m of the ocean. Lined stormwater evaporation and unlined stormwater infiltration basins on the south- eastern portion of the site are within 180 of the ocean. Six monitoring bores distributed mainly around the site boundary and also adjacent to the evaporation pond and infiltration basin are monitored quarterly for nutrients. Although not specified in the material received, we understand from other information at hand [Smith and Johnston, 2003], these bores have 3-m screens across the water table.
Monitoring detected a dramatic increase to 116 mg/L total N in the bore adjacent to the unlined infiltration basin in May 2004. This prompted some remedial work to the pond and while nitrogen concentrations in groundwater have reduced, total N in sampled groundwater was around 30 mg/L in this particular bore in May 2005 (range was 12 – 31 mg/L for the six bores on the same date). The tendency for the monitoring bores to be placed at the site extremities, rather than downgradient of the main handling areas, and the length and placement of the screens do not provide a full picture of the distribution of nutrient contamination under the site. This makes attribution of the source of nitrogen difficult, particularly in relation to the up-gradient BHP Billiton Kwinana Nickel Refinery site. Hence this plume seems to warrant further investigation.
5.2.13 CIK/NUFARM The disposal of herbicides/pesticides (particularly chlorophenols) nearly 2 km from Cockburn Sound at the former Chemicals Industries Kwinana (CIK) site now occupied by Nufarm Coogee has produced a relatively extensive plume of contaminants in groundwater. On-site monitoring (six bores, variously screened in the Safety Bay Sand aquifer) presents an incomplete picture of the plume. However, monitoring at other sites nearby (TiWest, BP Refinery, CSBP) and specific investigations paint a picture of wider contamination and suggests the plume has advanced at least within 1 km of Cockburn Sound.
However, uncertainty about the location of the plume in the aquifer sequences and fate of the contaminants in the groundwater system precludes a definitive conclusion as to whether or not this plume will impinge on the sediments or water quality of Cockburn Sound itself. In the face of this uncertainty, and the possibility that it will eventually reach the Cockburn Sound, management of this plume should remain a priority within the Cockburn Sound catchment.
6 Management Gaps and Research Opportunities
Environmental management of the unique Cockburn Sound ecosystem must balance the diverse needs of all stakeholders whilst attempting to protect agreed environmental values. This is a complex and fluid task, subject to changing environmental circumstance and social and economic context. Regular review of the management process is necessary to improve practices and standards, and to adapt systems to the changing demands. Several major industrial redevelopments and urban/infrastructure initiatives planned for the catchment represent potentially significant challenges for the environmental management of the Sound. In order to meet these challenges,
90 Status of Groundwater Quality in the Cockburn Sound Catchment
environmental managers may need to improve their understanding of the relationships between terrestrial land use practices and ecosystem integrity in Cockburn Sound.
Apart from direct drainage (stormwater systems or industrial effluent channels), groundwater remains the dominant pathway by which contaminants from terrestrial sources can access the Sound directly, yet this pathway is still relatively poorly understood and cannot easily be regulated or intercepted. A range of new groundwater quality measures may need to be considered to inform the management process in preparation for future challenges. In the following text we highlight several current management gaps and opportunities for improvement of management practice in the area of groundwater quality.
6.1 INTEGRATED PLANNING PRACTICES With the burgeoning economic and urban activity in the catchment, the need for integrated planning is stronger than ever. The explicit inclusion of environmental expertise on WAPC, CPCC and various committees, e.g. the Fremantle Outer Harbour Steering Committee, is a welcome step. Access to expert environmental advice is critical for scoping development proposals and initiatives for Cockburn Sound, especially in view of the strong linkages between land-use and groundwater quality in the catchment. It is unlikely that a single planning body can maintain in-house the required environmental skills in marine and terrestrial science which would allow the most efficient screening of development initial concepts. In some cases, as a result, environmental approvals are sometimes sought well after significant effort has been expended in the development of proposals, placing undue stress on the environmental impact assessment process, and incurring expense where developments are unlikely to proceed due to potential or unforeseen environmental impacts. For this reason, it is recommended that DoE consider how to further strengthen its relationships with EPA, DPI, WAPC and LGAs so that its environmental expertise can be accessed more easily and earlier in the proposal and planning development process, especially with respect to potential groundwater quality implications of new planning initiatives. A potential goal may be the routine inclusion of groundwater quality impact statements in the EPA approval process for all planning initiatives in Cockburn Sound and its catchment. The LPPCSC model for planning integration at the local level may be useful for consideration at higher levels.
Recommendation R.1 It is recommended that CSMC request that the EPA consider including groundwater quality impact statements in all major planning environmental assessments for areas within Cockburn Sound and its catchment. Furthermore, it is recommended that the DPI and relevant local governments ensure that due consideration for groundwater impacts of development proposals is given at all stages of the planning approval process and that collaborative linkages with the DoE in this area are strengthened.
6.2 PROXIMATE VULNERABILITY ZONE Some classes of groundwater contamination can potentially be ameliorated or reduced by the natural degradative capacity of the aquifers. Where this occurs, lengths of contaminant plumes can reach a steady state, i.e. the rate of replenishment of the contaminant at the source is balanced by the natural degradation rate of the contaminant throughout the plume. In such cases, plumes develop to a maximum length and then remain that size until the source of contamination is removed. Typical examples are dissolved phase petroleum hydrocarbon plumes, which may extend up to a kilometre in length (under the right flow conditions) before they are limited by natural degradation processes. Therefore certain kinds of plumes far inland in the catchment may have
91 negligible prospect of presenting risk of direct environmental impact to the Sound. The converse of this is that many plumes located close to the shore of the Sound are potential sources of environmental impact, even when the effects of natural degradation processes are taken into account.
The regulatory framework for point source contaminations [EPA, 1986; EPR, 1987] makes no explicit distinction between terrestrial locations proximate to sensitive or high- value ecosystems and terrestrial locations far removed from such ecosystems. At a policy level, the SECSP [2005] specifies areas of High, Moderate and Low ecological protection within the body of the Sound and associated seawater quality guidelines, but there are no specific statements or guidelines mentioned for the near-shore terrestrial zone. The link between Cockburn Sound environmental values and catchment management is made explicit in the EMP [EMPCSC, 2005] (the implementation tool for SECSP), however, at the broader levels, the absence of general linkages between terrestrial groundwater and surface water in the framework of the Act and Regulations is a potential regulatory weakness. There is scope to consider how the Act and Regulations may be improved by forming explicit linkages between terrestrial and aquatic environmental protection.
It is appropriate to consider a systems approach to environmental management in the Sound, i.e. reinforce the management scrutiny of the terrestrial system already discussed in EMP and the LPPCSC (‘special control area’). One means of reinforcement is to establish a terrestrial zone of “proximate vulnerability” along the Cockburn Sound shoreline. This zone is a conceptual tool for assessing the potential for impact from point sources of contamination in the vicinity of the Cockburn Sound shore. Sources of biodegradable contamination within the Proximate Vulnerability Zone would attract a higher level of management scrutiny than would sources of biodegradable contamination elsewhere in the catchment. The exact geographic definition of the Proximate Vulnerability Zone is likely to be problematic if approached on a contaminant-specific basis, as this would entrain significant scientific resources simply to measure biodegradation rates in all possible combinations of location and soil type. It would be more easily managed if a blanket zone width was used, e.g. everywhere within a certain distance of the shore of the Sound. If used in concert with the prescribed premises licensing and registration processes, the Proximate Vulnerability Zone could provide a useful first-pass risk management tool for the catchment. Specific examples of biodegradable contaminants that may be in scope for the Proximate Vulnerability Zone include nutrients, petroleum hydrocarbons, pathogens, pesticides, herbicides and acids.
Assessing the actual width of the Proximate Vulnerability Zone must take into account the time taken to identify and characterize any new plume, and then to develop and implement an appropriate management plan for the plume. Considering the difficulty of characterizing plumes in the Superficial Aquifer, and the long lead times involved in instituting appropriate management responses for significant contaminations, we suggest that an appropriate time allowance is of the order of 20 years. That is, the location of the Proximate Vulnerability Zone boundary should be such that new plumes arising on the boundary within the Superficial Aquifer should take at least 20 years to reach the shoreline. Using a hydraulic conductivity estimate of K = 50 m/d, porosity of 0.3 and an (conservative) hydraulic gradient of 0.002 yields a 20 year travel distance of approximately 2.5 km. This value may overestimate plume migration distance in the Safety Bay Sand, but underestimate migration distance in the Tamala Limestone. In order to provide an extra margin for error for plumes in the limestone, we recommend that a width of 3 km (from the coast) be adopted for the Proximate Vulnerability Zone.
In practical terms, the adoption of the Proximate Vulnerability Zone might best be implemented by requiring that all prescribed premises within the zone be licensed, with the specification of a minimal, default set of licence conditions (see Section 6.2) for premises where no conditions currently apply
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One possible benefit of the proximate zoning would be to raise general community awareness of the potential vulnerability of the Sound to particular kinds of chemical use along its direct margins. Another possible benefit is that the proximate zoning may lead to improved industrial and land use planning. In this sense, the decision to site a new industrial development further inland at Hope Valley is a positive move for Cockburn Sound, in that it lessens risks of direct impact to the Sound from certain classes of contaminants in the new development. This of course ignores other local land and groundwater values local to the Hope Valley area, which in addition would need to be assessed.
It is important to note that some kinds of groundwater contamination are not readily degraded by natural process in the Cockburn Sound aquifer system. These contaminants commonly include nutrients (nitrogen and phosphorus species) and alkalis (because of the high carbonate content of the local aquifers). It is possible for such contaminant plumes to migrate for many kilometres without significant reduction in concentration other than by hydrodynamic dispersion or by dilution by recharging rainwaters. The specification of a short proximate zone is not particularly helpful in these non-degradable cases, since plumes outside the zone may still potentially impact the Sound. However the longer travel time to the Sound, coupled with appropriate licence conditions for monitoring local groundwater quality, still means that there should be ample warning given of any problematic plume so that an appropriate management response could be made.
Recommendation R.2 It is recommended that CSMC consider the establishment of a Proximate Vulnerability Zone along the Cockburn Sound shoreline. All prescribed premises within the Zone should be required to institute at least the default groundwater monitoring program (see Section 6.2.2).
6.3 LICENCE CONDITIONS
6.3.1 REGULAR REVIEWS Licence conditions are the prime mechanism by which DoE can monitor the environmental performance of industries assessed as posing significant potential risk in the catchment. Following the Welker report [WEC, 2003], the focus of licensing shifted to the quantity of emissions permitted from each premises. In terms of groundwater quality, the emission calculations are based on contaminant levels abstracted from groundwater monitoring bores at each of the licensed premises. These are normally aligned with identified emission points or discharge points. It appears to be the usual practice that licence conditions are administered on a fixed basis, i.e. apart from an annual re-licensing procedure there seems to be little evidence of a regular and formal practice of comprehensive review of licence conditions in the light of changing industrial practices or changing conditions across the catchment. If so, this is a management gap that needs to be addressed. For example, it may be appropriate to review all licence conditions every five years or earlier if industrial practices at individual premises change significantly. This is especially important if general conditions of groundwater quality throughout the catchment deteriorate.
Recommendation R.3 It is recommended that CSMC request that the DoE re-examine the current practice of licence renewal and comprehensive review to ensure that updating of licence conditions
93 relevant to environmental parameters reflects environmental trends in Cockburn Sound and its catchment.
6.3.2 DEFAULT SUITE OF ANALYTES Under Section 58 of Part V of EPA [1986], DoE is able to amend licence conditions (in the manner described in Section 59B). Furthermore, there is some leeway under Section 60 for DoE to apply more stringent environmental conditions to licences than are required by approved policies or prescribed standards. This represents significant power to impose conditions in areas of particularly high environmental value. Given the generally cooperative relationships between DoE and most stakeholders in the catchment, it is unlikely that formal actions under the provisions of Section 60 would be required. However, in view of the uneven nature of licence conditions applied across the catchment there is the opportunity to seek to enhance the range of analytes tested by default as part of licence conditions, often at negligible marginal cost to occupiers of licensed premises. The concept of a default range of analytes was also put forward by DAL [2001].
The recommended default suite of analytes is: • pH • Redox Potential (Eh) • Electrical Conductivity (EC) • Total Dissolved Solids (TDS) • Major Ions • Total Nitrogen (as mg N per litre)
• Nitrate (NO3 as mg N per litre)
• Nitrite (NO2 as mg N per litre)
• Ammonium (NH4 as mg N per litre) • Total Petroleum Hydrocarbons (TPH) • Total Organic Carbon (TOC)
Phosphorus is not included on the grounds that it is thought not to be a dominant control of eutrophication in the Sound. The nitrogen species are listed individually in order to maintain consistency with historical records and to support detailed analysis of spatial nutrient dynamics in the groundwater (sulphate is measured as part of the Major Ions test). The total organic carbon and the total petroleum hydrocarbons measures together provide a simple measure of organic contamination and a first-pass assessment of the common petroleum components. The application of this list would be extended on a case-by-case basis by site-specific licence conditions, taking into account site-specific industrial practices and historical groundwater quality records. For example, new premises with no previous record of groundwater contamination may simply adopt the default suite above, whilst a heavy industrial premises might add metals and semi-volatile organic analytes to their monitoring suite.
It is normal practice for DoE to impose licence conditions that stipulate specific analytes related to the handling or storage of wastes at each licensed premises, pursuant to EPA Part V s. 62A(3). It is unusual to require monitoring of analytes not used in the normal operations of the premises. For some premises the application of the above default suite of analytes may include substances that are not handled by the premises, which may present some difficulties in implementing the default suite across of prescribed premises. However, as embodied in s. 60(3) and s. 62 of EPA [1986], there is room for DoE to
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impose extra licence conditions above and beyond approved policies and normal substance lists for each premises.
Recommendation R.4 It is recommended that CSMC request that the DoE consider adopting the default suite of analytes as a minimum standard of groundwater monitoring at prescribed premises in the catchment.
6.3.3 MINIMUM MONITORING REQUIREMENTS FOR SITES Prescribed premises are those categories of operations identified in EPR [1987] that intrinsically carry the potential for environmental harm if management systems fail. Not all prescribed premises are given licence conditions by DoE; many of these have no groundwater monitoring systems and often no groundwater management plan. The rationale is that there is no expectation or evidence of contamination at these registered sites. This may be so, but this viewpoint is not consistent with the precautionary principle inherent in both the EPA [1986] and the SECSP [2005] for managing Cockburn Sound. It is likely that most major, sudden incidents of unexpected waste emission or discharge (e.g. catastrophic equipment failures) will be brought to DoE’s attention, however many significant sources of groundwater contamination originate from long-term or chronic low- level discharges that may go unnoticed because of their systematic nature. Since these instances cannot be predicted, it would be prudent to institute watchdog groundwater monitoring activities at all prescribed premises, both licensed and registered, and especially prescribed premises within the Proximate Vulnerability Zone for Cockburn Sound.
A reasonable minimum standard for groundwater monitoring systems would be two bore locations, one upgradient of the site and one downgradient, with the defined line passing through the main waste/chemical handling or storage location on the site. Each location should penetrate to the top of the Cretaceous sediments, i.e. to the bottom of the Tamala Limestone, and be screened over two intervals. The upper screen should be at the water table and the lower screen should be located near the base of the Tamala Limestone formation. Where there is evidence of a significant aquitard between the sand and limestone formations, an intermediate screen location may be advisable. The screens would potentially sample contamination from dense and less dense species. Fluid samples should be taken from each screen of each bore on a six-monthly basis and tested for the default suite of analytes (Section 6.2.2). Testing results should be supplied to DoE on a 6 monthly basis together with a clear summary highlighting exceedances or results of potential concern.
Where existing licence conditions are more stringent than the above minimum monitoring requirements, the latter could be waived. For example, some licensed premises in the catchment are already monitoring tens or hundreds or bores; in these cases it is unlikely to be necessary to add two extra bores. However the sample tests for all licensed premises should include at least the default suite of analytes. It is recommended that at least the minimum monitoring requirements be adopted by all prescribed premises located within the Proximate Vulnerability Zone. Where premises have multiple chemical storage and handling facilities or evidence of groundwater contamination, DoE should require a greater level of groundwater monitoring above the minimum requirement. In any event, adoption of the minimum monitoring requirement throughout the catchment should not be a cause to reduce any licensed monitoring programs presently required by DoE. The intent is simply to bring at least a minimum standard of groundwater monitoring to all prescribed premises in the Proximate Vulnerability Zone, and all licensed and registered premises elsewhere in the catchment.
95
Recommendation R.5 It is recommended that CSMC request that the DoE consider developing a minimum groundwater monitoring configuration for prescribed premises in the Proximate Vulnerability Zone, requiring at least two bores (upgradient and downgradient of major waste handling and storage areas on site), with separate screens at the base of the Superficial Aquifer and at the water table in each bore. Samples from each screen should be tested for the default suite of analytes and reported to DoE on a 6 monthly basis, with all exceedances of licence conditions and/or marine trigger values noted.
6.4 INSPECTIONS OF PRESCRIBED PREMISES Inspections are an essential part of the enforcement provisions of Part VI of the EPA [1986]. Apart from assisting in the regulation of environmental practices, inspections can be a valuable means of establishing and promoting relationships between regulators and stakeholders, and also of promoting general awareness of the relationships between waste handling practices and environmental values across the catchment. It is recommended that each licensed premises in the catchment and each prescribed premises in the proximate zone be inspected annually; each inspection should include a physical visit from a DoE inspector.
Recommendation R.6 It is recommended that CSMC request that the DoE consider that each licensed premises in the catchment and each prescribed premises in the Proximate Vulnerability Zone is inspected annually for compliance with environmental standards and licence conditions; each inspection should include a physical visit and appropriate reporting to file.
6.5 UNREGULATED SITES Businesses that fall outside the prescribed premises and registered premises categories fall under LGA environmental and health management responsibility. This general commercial sector includes a vast number of small to medium sized enterprises (SMEs) distributed across the catchment. It was estimated that 95% of all industrial premises in Perth fall outside the prescribed premises categories [DoE, 2004, p. 179]. Whilst these premises are still governed by the general principles of EPA [1986] and related instruments, they are subject to a much lower level of environmental scrutiny and are unlicensed with respect to waste emissions and discharges, essentially for reasons of individual scale and lower assessed environmental risk. However, due to the sheer numbers of SMEs and the clustered zones of light industrial and commercial districts in the catchment, there is associated potential for significant reductions in groundwater quality. This issue has been recognized by DoE and is presently being addressed through management and education programs rather than through amendments of existing regulations.
The LGAs in the catchment presently collect data on business registrations in their areas and normally work with SMEs to inform them of their environmental obligations. Annual inspections are also carried out to various extents across the LGAs. However, aggregation and compilation of business registration data (especially with respect to hazardous chemicals use, emissions and waste disposal practices) is not coordinated across the Cockburn Sound catchment. At a strategic environmental management level, there is no simple means to either map or assess the consequent or potential impact on
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groundwater quality of light industrial/commercial activities across the catchment other than by land use zoning.
At the same time, the capacity for the LGAs to absorb the demands of extra information gathering and processing is limited. It is therefore recommended that a simple screening survey, e.g. a one-page multiple-choice questionnaire, be produced and filled out as part of the environmental management assessment for each new business registration at the LGA level. The survey would be directed at identifying the use or production of materials listed in EPUDR [2004] (see Section 3.1.8) and, where appropriate, identifying approximate volumes of these materials handled annually, e.g. < 50 litres of chlorophenols per year. The survey could also identify the kinds of stormwater and/or runoff interception and discharge technologies used on the premises, as well as the waste disposal arrangements. Survey results would be easy to incorporate into databases at LGA and State agency levels, so that spatial data analysis of chemical production and use would be facilitated across management boundaries.
Recommendation R.7 It is recommended that CSMC and LGAs work together to develop a brief hazardous wastes survey for all new business registrations in the catchment. The resulting information should be compiled by LGAs into a spatial database for ready input to planning and environmental management activities at LGA and State Government levels.
6.6 GROUNDWATER QUALITY MONITORING
6.6.1 CATCHMENT SCALE MONITORING The state of groundwater quality is presently poorly understood at the catchment scale. From 1962 DoE maintained a network of up to 34 groundwater monitoring bores across the catchment, regularly testing for a range of analytes including nutrients, inorganic parameter and various classes of organic compounds. Unfortunately, all DoE monitoring of nutrient concentrations, which are generally regarded to be the prime eutrophiers for Cockburn Sound, apparently ceased by 2000. The sole sources of nutrient data that now exist are the data that may be required to be supplied under the licence conditions of some (not all) prescribed premises, plus the water quality data measured routinely by Water Corporation at their production bores outside the catchment boundary on the Jandakot Mound. The lack of a comprehensive nutrient sampling plan for groundwater across the catchment is a major impediment to understanding and managing the groundwater nutrient budget for Cockburn Sound.
It is recommended that DoE re-establish a regular groundwater quality sampling program across the catchment (see Section 5.1.1). This should involve a series of bores chosen primarily to test key catchment scale water quality indicators, e.g. nutrient species, rather than be used directly to sample local plumes from point contaminations. Each bore should be screened at the water table and at the base of the Superficial Aquifer. A set of three of four “fences” of bores running parallel to the coast at different distances inland would seem to be appropriate for the purpose of measuring large-scale water quality changes from diffuse sources such as land use changes and major redevelopments. Further spatial resolution would be achieved by adding nutrient data reported by premises within the proximate vulnerability zone and by licensed premises elsewhere in the catchment. Sampling should be performed at all bores at annual intervals or more frequently. It is important that the groundwater quality sampling program be re-
97 established as a priority so that adequate baseline information can be gathered before major redevelopments commence.
Recommendation R.8 It is recommended that CSMC request that the DoE/DoW consider re-establishing a regular groundwater quality sampling program across the catchment consisting of at least thirty (30) bores. Each bore should be screened separately at the water table and at the base of the Superficial Aquifer. This program should be given high priority so that adequate baseline information can be gathered before major redevelopments commence.
6.6.2 PLUME MONITORING This study and others [Smith and Johnston, 2003] recognise the importance of several high-concentration plumes in delivering the majority of the nutrient flux to Cockburn Sound. From north to south, these are the plume(s) coming from the (i) Water Corporation sludge drying beds and Woodman Point, (ii) the Love Starches/Western Bioproducts/Nagata precinct, (iii) in the vicinity of Alcoa (iv) in the vicinity of the HIsmelt facility (v) near CSBP, FPA and United Farmers south of James point, In addition, sites of high priority for investigation related to nutrients are BHP Billiton’s (formerly WMC) Kwinana Nickel Refinery, Summit Fertilizers, Coogee Chemicals, Doral Speciality Chemicals and Garden Island sewage disposal facility at HMAS Stirling (see Table 5.1).
Apart from nutrients, this review also recognises the importance of several other contaminant plumes – the ‘orphaned’ Chemical Industries Kwinana (CIK) chlorophenol plume, petroleum hydrocarbon plumes underneath the BP Refinery, and several of the landfills in the area.
Detailed investigation and quantification of processes is underway at some of these sites to determine plume distributions and ultimately their contaminant fluxes into Cockburn Sound. For example, extensive soil and groundwater characterisation has been carried out at the BP Refinery with further investigations planned. However, the data intensity and spread of effort is not uniform across the different plumes and source areas. This is somewhat understandable given the differing chemicals of concern and different management objectives. Despite this, increased investigation and definition of plume dimensions for a number of the plumes or potential sources is recommended
In particular for the nutrient plumes indicated in (i) – (v) above, it is proposed that focused monitoring be established with a view to better estimation of the width and depth of these plumes to assist with better estimation of net discharge to the Sound, and for tracking the performance of management. This would involve installation of additional monitoring bores across the flow direction of groundwater (the full width of the plumes), and defining the plume depth and thickness at these locations.
Recommendation R.9 It is recommended that further investigation of the depth and width of the high priority nutrient plumes in the catchment be undertaken to better define plume dimensions, peak
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concentrations and mass fluxes discharging towards Cockburn Sound. Periodic monitoring would provide performance measures for management initiatives.
Following on from R.8, where they do not exist, management plans should be established for the most prominent nutrient plumes in the catchment. Active management (groundwater pumping) has been carried out in the Northern Harbour area to capture nutrient plumes emanating from the Water Corporation’s sludge drying beds and the old Love Starches factory. In addition, Alcoa and CSBP have active recovery programs. To date, the effectiveness of the recovery strategies is unclear, and the end-point targets remain uncertain. A review of recovery targets and end-points would assist with future management decisions for these important inputs to Cockburn Sound.
Recommendation R.10 It is recommended that management plans be developed for the most prominent plumes in the Cockburn Sound Catchment and performance criteria be established for reduction of chemical mass flux to Cockburn Sound.
6.7 INFORMATION MANAGEMENT The present system for managing catchment data within DoE is in need of overhaul. This has already been recognised by DoE and the improvement process is underway. At the risk of covering old ground, we list here some desirable features of the system that would greatly simplify environmental management of the Cockburn Sound catchment. The recommended features extend beyond DoE into other State agencies and LGAs.
6.7.1 PRESCRIBED AND NON-PRESCRIBED PREMISES LISTINGS DoE presently maintains records of licensed and registered prescribed premises within the catchment which, when cross-referenced with prescribed premises category number (under EPR [1987]), can provide rapid assessments of potential contaminant types and locations across the catchment. However, the information is presently lacking useful spatial reference which hinders efficient spatial mapping of prescribed premises categories across the catchment. Ensuring that licensed and registered premises are listed along with spatial location data (centroid eastings and northings) would be a simple but powerful improvement. Of course, prescribed premises listings only present part of the groundwater quality picture. There are many more premises in the catchment with potential to impact groundwater quality significantly; however these are outside DoE’s ambit. LGAs routinely collect information on new businesses and it would benefit environmental management practice to be able to combine and query data from both prescribed and non-prescribed premises across the catchment. The recommended LGA business environmental survey data could be included here. It is noted that DoE was already working toward the spatial referencing of premises data by the commencement of this study, and that sourcing up to date cadastral information is paramount.
Recommendation R.11 It is recommended that CSMC request that DoE continue its efforts in spatial referencing of premises and licensing data with the goal to construct a single comprehensive database of groundwater monitoring data in the catchment.
99 6.7.2 COMMUNITY INVOLVEMENT PRACTICES Under the pending Contaminated Sites Act [CSA, 2003], DoE will be obliged to produce and maintain a public database of contaminated sites. This would be a positive partial step towards a comprehensive and transparent environmental management system for WA. However, due to the unique values and contexts of Cockburn Sound and the major redevelopments planned for the catchment, the need for a higher level of systems management is indicated. The environmental management function would best be served by the creation of an electronic database of licensed and registered premises, combined with listings of premises that fall outside the prescribed premises categories but that store or produce significant quantities of the materials listed under EPUDR [2004], as reproduced in Section 3.1.8. Extra data sets in the database may include parks and reserves, significant wetlands, and groundwater quality indicators (e.g. from the recommended catchment scale water quality monitoring program). It is noted that DoE was already working toward the consolidation of premises data by the commencement of this study.
Since the future of Cockburn Sound will be determined ultimately by community attitudes, it is important to involve the community directly in environmental management. The present CSMC practice of issuing annual Report Cards (which summarise the status of environmental values) has generally been well received. In planning for future community involvement, this direct communication concept needs to be expanded. A new Report Card should be developed to cover groundwater aspects, especially the condition of diffuse nutrient contamination across the catchment. One possible style of groundwater report card would be to show graphs of annual averages of total nitrogen concentrations at monitored locations across the catchment, with marine water, fresh water and drinking water guideline levels drawn on the same graphs for reference. Additionally, depending on information and database advances, the CSMC could work towards a report card that also summarises changes in flux estimates over time, as the net nutrient flux is likely to control ecological health of the Sound, rather than concentration changes alone. It is also recommended that the Report Cards concept be strengthened by the addition of a publicly accessible database containing data sets discussed above and made available over the web for general inspection. Access to both the Report Cards and the more detailed database service allows members of the community to select the level of information that is appropriate to their needs. The free flow of information may also assist industrial stakeholders gather extra perspective on the state of groundwater contamination outside their premises.
Recommendation R.12 It is recommended that CSMC consider the development of a new Report Card for groundwater contamination in the catchment. Groundwater nutrient levels should be a key indicator of contamination state, but consideration should also be given to flux estimates. This data would largely flow from Recommendation R.8.
6.8 COCKBURN SOUND RESEARCH Cockburn Sound is iconic and faces challenging issues of utility and ecological function, increasing population and industry growth, and changed land use patterns and community expectations. Altogether, there are complex management and research issues that need attention. Some of the research issues are described below. However, it is clear that substantial resources are needed to address the research activities and investigations required to underpin effective management decisions. Many of the land planning and management issues are being addressed through the Cockburn Sound Management Council and associated industry, regulatory and community actions. Currently some research and investigation is supported directly by the CSMC, the Kwinana Industries Council, by individual industries, DoD at HMAS Stirling, and via other
100 Status of Groundwater Quality in the Cockburn Sound Catchment
avenues. Despite the current efforts, the research and investigation required to support management actions is limited. The needs are diverse and extensive and much more research is warranted.
To meet the required strategic research effort, it is recommended that a research body be formed with a remit to commission, direct and coordinate strategic research activities that will underpin management decisions affecting Cockburn Sound. The research body would have a catchment wide brief, to assess contributions from different land uses via stormwater, run-off and groundwater, and in addition the body would consider total water cycle issues in the catchment in view of the increasing water imports to the catchment and potential increased effluent production. Terrestrial inputs and issues would need to be interfaced with near-shore and Sound-wide issues. In this way the body would unite marine, atmospheric and terrestrial research to provide the best possible integrated research outcomes for Cockburn Sound, and potentially for other (national and international) urban/marine systems.
Two structural models for the research body would seem to be appropriate. The first is a sub-committee model for CSMC itself, with the research sub-committee able to share CSMC’s existing administrative resources. The sub-committee’s task would be to assemble multi-disciplinary teams from interested research providers (research agencies, industry, consultants, State agencies) to address the strategic research priorities set by CSMC. This structural model engenders minimum overheads, but also may not have the critical international scientific mass to become a strategic research focal point for the wider Cockburn Sound ecosystem.
The second, preferred, model is to establish a Cockburn Sound Environmental Systems Research Centre. The Centre would be a collaborative effort between research providers, CSMC and other interested parties. To be successful, core State Government funds would need to be provided to stimulate and advance strategic science for the Cockburn Sound catchment. Some funding would also be required to support Centre administration. Additional funding would be sourced through Federal Government funding mechanisms, and continue to be provided by industry and other avenues where specific issues need to be addressed. A Centre Director would be charged with coordinating and establishing research programs under priorities set by a research advisory committee. Research providers would co-invest to participate in the research efforts. The focus would be to establish the Centre as a source of high quality integrated marine and terrestrial scientific research.
Recommendation R.13 It is recommended that CSMC consider requesting State Government support for the establishment of a Cockburn Sound Environmental Systems Research Centre, with a remit to pursue strategic research and to provide research support for management decisions affecting the wider Cockburn Sound ecosystem, especially with respect to terrestrial influences and impacts on the Sound. It is also recommended that the terms of reference and structure of the new Centre are to be decided by CSMC in consultation with stakeholders.
6.8.1 SCIENCE GAPS It has been noted by many authors [e.g. Smith and Johnston, 2003] that estimates of groundwater nutrient discharge into Cockburn Sound carry significant uncertainty. This is mainly due to the scarcity of nutrient data from further inland in the catchment, and the difficulty of characterising the small scale discharge rates to the Sound. Nutrient
101 discharge estimates will not improve in certainty until advances are made in these two key areas.
A second major knowledge gap is in how groundwater contaminants of different kinds may actually impact the ecosystem of the Sound directly. This is less of a problem for the dominant nutrient contaminant (nitrogen), but is certainly an issue for many other contaminant types, especially petroleum hydrocarbons, semi-volatile organics, pesticides, endocrine disruptors, metals etc. The particular research question to be asked here is what is the threshold groundwater concentration of a particular contaminant that translates into ecosystem impact to the body of Cockburn Sound?
In the following sections we propose research studies targeted at improving the scientific understanding of these issues in Cockburn Sound.
6.8.1.1 HYDROGEOLOGICAL CHARACTERIZATION AND DISCHARGE MAPPING The general principles of surface water – groundwater interaction are well known. Surface waters can be conceptualised as zones of high hydraulic conductivity which tend to act as foci for the underlying groundwater flow regimes. This theoretical picture has been validated in the field using a variety of physical, geochemical and isotopic techniques. The theory works best for uniform sandy aquifers; agreement is poor for aquifers characterized by significant spatial heterogeneity. In Cockburn Sound, the Superficial Aquifer system is a complex mixture of sandy layers and highly heterogeneous limestone layers. Although this has long been recognized, no significant attempt has been made to characterize the spatial properties of the Superficial Aquifer across the catchment. This knowledge gap represents a major obstacle to the understanding of water quality issues in the catchment, especially in terms of how contaminated groundwaters reside and migrate in the subsurface, and how and where they eventually access Cockburn Sound. Redressing this knowledge gap is crucial for the future environmental management of a system containing both the largest industrial precinct in WA and its most highly valued marine embayment.
It is proposed that a study be set up to define and measure the spatial properties in the Superficial Aquifer in the Cockburn Sound catchment, focusing on the Proximate Vulnerability Zone. Physical, geological, geochemical and hydraulic properties of the aquifer would be in scope. It is envisaged that this study would probably employ a mixture of isotopic, geochemical, geophysical, satellite remote sensing and hydrological measurement technologies. Key outputs would be spatial descriptions of propensity to (and statistics of) preferential flow and secondary porosity, improved maps of groundwater head in the various layers, improved mapping of saline wedge processes, and estimates of groundwater discharge rate along the bed of Cockburn Sound. These outputs, together with improved catchment and plume scale groundwater quality monitoring, would feed into more accurate assessments of discharge flux to Cockburn Sound. Having a firm statistical description of the aquifer properties would permit more sophisticated scenario analysis methods (e.g. Monte Carlo techniques) for assessing potential impacts of present and future contamination.
This study would best be undertaken as a coordinated effort between research providers, so that skills present in the wider research community could be brought together to tackle the various tasks. In order to undertake the relevant literature reviews, design and perform the required range of field studies and to analyse and report on the outcomes, it is envisaged that the study would run for approximately three years. This is long enough to involve post-graduate students on associated research topics and also to ensure significant involvement of supervising scientists from the various organizations. The
102 Status of Groundwater Quality in the Cockburn Sound Catchment
budget also needs to cater for the range of sampling techniques suggested above and the subsequent analysis of data over the three years.
6.8.1.2 BIOGEOCHEMICAL TRANSFORMATIONS IN THE HYPOAKTIC ZONE The hypoaktic zone is defined as the aquifer zone immediately contiguous to the seabed sediments. This zone is similar to the hyporheic zone of inland freshwater systems; for hypoaktic systems the essential feature is the presence of dense, hydrochemically complex fluids in the surface waters. Hypoaktic zones are characterized by complex biogeochemical processes, convective flow regimes and multiple temporal and spatial scales; it is these zones where contaminated groundwater first encounters surface water and marine flora and fauna. In the environmental context, it is necessary to study and measure the fates of groundwater contaminants in the local hypoaktic environment before fluxes to the wider ecosystem can be estimated. For example, some organic chemicals may rapidly degrade in aerobic or sub-oxic sediments near the intertidal zone, whilst other contaminants may be more long-lived. Potential effects of seawater dilution of groundwater immediately after leaving the sediments need also to be assessed.
It is proposed that a study be commenced to measure natural degradation rates of key chemical species in near-shore sediments in Cockburn Sound. The emphasis would be on estimating attenuation factors for concentrations of contaminants as the groundwater fluid moves through the hypoaktic zone into the marine waters. In order to restrict the study to manageable proportions, attention should be confined to several major classes of contamination of particular interest in Cockburn Sound, e.g. petroleum hydrocarbons, nutrients, alkalis, chlorinated solvents and metals. Outputs of this study would be data that could be combined with groundwater:marine water dilution factors for Cockburn Sound to estimate effective contaminant threshold concentrations in groundwater that relate to the ANZECC/ARMCANZ trigger values for inshore marine waters (see Section 3.3.3). If successful, this research study would provide a firm research basis for assessing risks to the environmental values of Cockburn Sound from individual contaminant plumes in the catchment.
This study would first characterize the hydrochemical environment in the hypoaktic sediments of Cockburn Sound and then study the intrinsic microbial populations in the sediments. The capacity of the sediments for attenuation of major contaminant classes would then be tested by parallel laboratory and field experimentation under different conditions of groundwater discharge flux and seasonal influences. This program of experimentation would require advanced chemical and microbiological analytical techniques, coupled with detailed knowledge of hypoaktic fluid dynamic processes in Cockburn Sound. This study could feasibly be carried out over 2-3 years.
6.8.1.3 STORMWATER CONTAMINATION PATHWAY The drainage of stormwater and general runoff in the catchment is largely unregulated in terms of discharging water quality. These waters are often highly contaminated with metals, hydrocarbons, nutrients and pathogens and have been associated with water quality impacts in Cockburn Sound and elsewhere in the Swan Coastal Plain. There is also potential for environmental harm to the lakes and wetlands within the Cockburn Sound catchment that are used to buffer and drain stormwater and runoff. There is a need to define the scope of the water quality problem associated with stormwater and runoff management practices in the Cockburn Sound catchment and the potential environmental impacts on Cockburn Sound.
This study should investigate the stormwater drainage networks operating in the catchment and estimate the drainage discharge fluxes to Cockburn Sound throughout the annual cycle. Water quality samples should be taken and analysed at key locations in the drainage network to assess contaminant loads against water quality standards and to identify sources and sinks in the network. Special attention should be placed on the role
103 of lakes and wetlands in storing, attenuating and discharging contaminants to the Cockburn Sound ecosystem. In order to capture inter-annual variations, this study would need to run over 18 months with a moderate sampling and analytical effort.
6.8.1.4 NUTRIENT CYCLING IN THE SEDIMENTS Currently, there is uncertainty as to the relationship between nutrient inputs to the Sound and chlorophyll readings, which are used as a surrogate index of the health of the Sound. This may be due to a number of reasons, one of which is the lack of understanding of nutrient cycling in the basal sediments of the Sound. This needs to be clarified.
The study would investigate the magnitude of the store of nitrogen in the shallow basal sediments, and the dynamics and timeframes for cycling into the water column as available nitrogen. This would necessarily involve carbon budgeting and nitrogen transformation studies to determine mass balance estimates for the fate of nitrogen. Likely seasonal influences in the cycling processes would suggest that a suitable timeframe for the study would be at least 2 years.
104 Status of Groundwater Quality in the Cockburn Sound Catchment
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112 Status of Groundwater Quality in the Cockburn Sound Catchment
Appendix 1: Risk Methodology Here we briefly describe a risk weighting methodology – not in terms of risk posed to human health or even the ecological value of the Sound per se, but as a tool to rank contaminants and premises where additional action or enhanced management strategies may be warranted. Because some premises have several contaminants of concern, it is not possible to rank just a site or just a chemical type at the one time. Here we rank chemicals initially, and then sites across the catchment that would be high priority for close management.
Some elements of the weighting were raised in Section 3.3.4. Overall the risk weighting was seen to depend on: • the prevalence and potential impact of the chemicals of concern – o their spatial density and volume of use through the catchment, o the proximity of their use or spillage to the Sound and o the local hydrogeological context. • the physico-chemical properties of the chemicals and groundwater conditions – this will dictate their persistence and behaviour. • the type of potential impact on the marine environment – whether toxic or causing ecological disturbance. • the uncertainty of knowledge about a contaminant or site • management that would lead to mitigated or attenuated affects – so implemented or planned management and the potential for success of that management.
A summary of the principal chemical classes and compounds is given in Table A1.1. The nitrogen-based nutrient species pose the highest risk. This is largely due to their actual impact on the water quality in the Sound and on their significant mobility. Those chemicals with moderate risks are phosphate, petroleum hydrocarbons, metals and the metalloid arsenic, and chlorophenols and solvents.
Although the petroleum hydrocarbons may attenuate naturally and strongly, they are given a moderate risk in this assessment, largely due to their widespread use and large volume storage in the catchment, and the very close proximity of fuel storages to the Sound. Metals achieve a moderate ranking since their distribution is uncertain, they can be toxic to aquatic biota and they are in wide spread use throughout the catchment – from domestic use, to power generation and to industry use. Pesticides/chlorophenols are given a moderate ranking due to the probably wide spread use across the catchment, and the known presence of a high concentration and persistent chlorophenol/phenol plume within 2 km of the Sound foreshore. Solvents are ranked as a medium risk due to the very high uncertainty of information about their use and actual discharge to the groundwater – especially due to the lack of groundwater quality data or targeted investigations, despite the presumed widespread use of solvents in the catchment. No solvent plumes are known to exist in the catchment, but it is well known that a small solvent spill can affect a large volume of an aquifer (see, e.g., Davis and Appleyard [1996]). Phosphate is ranked as a medium risk due to its widespread use and potential support of eutrophication processes – although its mobility would be less than the nitrogen species. Pharmaceuticals are ranked with a moderate risk due to the high level of uncertainty as to their persistence and effects, and their likely widespread disposal through the catchment via septic tank use.
Based on this assessment, an additional screening of sites and instances was carried out. Sites and instances that were in close proximity to the Sound and were known or inferred to have these high or moderate risk chemicals stored or already contaminating groundwater
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were selected to be part of a priority list. The full list is presented in Table A1.2, and the priority site list is shown in Table 5.1.
Spatial Density Potential Knowledge and Proximity Impact or Volume of to the on Information Overall Risk to Chemical type Use Sound Mobility* Sound Uncertainty Cockburn Sound Nitrogen Oxides High <500 m High High Low High Ammonium High <500 m High High Low High Phosphate Moderate <500 m Moderate Moderate Moderate Moderate to low Pesticides Moderate 1-2 km Moderate Moderate Moderate Moderate Petroleum fuels High <500 m Moderate Low- Low Moderate Moderate Solvents Moderate- <500 m Moderate Low- High Moderate High Moderate Metals Moderate- <500 m Low Moderate- Moderate- Moderate High High High Arsenic Moderate <500 m Moderate Moderate- Moderate- Moderate High High Pharmaceuticals Moderate- <500 m Unknown Unknown High Moderate High Pathogens Moderate- <500 m Low- Low Moderate- Low-Moderate High Moderate High Caustic Solutions Moderate <500 m High Low- Moderate Low-Moderate (high pH) Moderate TDS High <500 m High Low Low Low Acid plumes (ASS) Low- 1-2 km Low- Moderate Moderate Low Moderate Moderate Sulphates Moderate <500 m High Low Low Low *Mobility accounts for its propensity to degrade, and be retarded in soil material. Table A1.1: Priority chemicals.
Distance to Plume Location Sound1 Contaminant(s) Monitoring Plume (m) Level Management BHP Billiton KNR 970 N species, sulphates, metals High yes CSBP 860 N species, metals High yes Water Corp Woodman Point 520 N species High yes Love Starches/Nagata2 650 N species Medium yes FPA/HIsmelt/LandCorp2 440 N species Medium no Septic Tanks/industrial and 50-5000 N species, pharmaceuticals Low no urban areas Horticulture 1000-3000 N species, phosphate, Low no pesticides Alcoa 290 N species, metals High yes Summit Fertilizers 1800 N species, phosphate Low no BP Refinery 640 petroleum hydrocarbons High yes United Farmers Cooperative 160 N species Low no CIK/Nufarm2 1970 chlorophenols Medium no Coogee Chemicals 1280 N species Low no Doral Specialty Chemicals 860 N species Low no DoD HMAS Stirling 620 N species Medium no Landfills > 1000 N species, organics, metals Medium-Low no 1 Approximate distance from the centre of premises lot to the nearest Cockburn Sound shore. 2 These plumes are historical and may pre-date the present occupiers of the premises. Table A1.2: Priority sites and instances, based on contributed information.
114 Status of Groundwater Quality in the Cockburn Sound Catchment
Appendix 2: Licensed Prescribed Premises
The following table lists all the licensed prescribed premises operating in or near to the Cockburn Sound catchment (supplied by DoE, 5 September 2005). A total of 83 prescribed premises are listed. Local Government # Name of Prescribed Premises Authority License Classification 1 9 Mile Quarry City of Cockburn Class I inert landfill site 2 A Richards Pty Ltd City of Cockburn Compost manufacturing and soil blending 3 AAA Bulk Haulage Landfill Town of Kwinana Class I inert landfill site 4 Abercrombie Road Resource Recovery Centre Town of Kwinana Solid waste depot 5 Advanced Pet Care Town of Kwinana Animal feed manufacturing 6 Air Liquide WA Pty Ltd City of Cockburn Chemical manufacturing 7 Alcoa Kwinana Alumina Refinery Town of Kwinana Bauxite refining 8 Amcor Packaging Australasia (Spearwood) City of Cockburn Class II or III putrescible landfill site 9 Asphalt Surfaces Pty Ltd City of Cockburn Asphalt manufacturing 10 Australian Drilling Specialties Pty Ltd Town of Kwinana Chemical manufacturing 11 Australian Fused Materials Pty Ltd City of Rockingham Mineral sands mining or processing 12 Australian Gold Reagents Pty. Ltd. Town of Kwinana Chemical manufacturing 13 Baileys Town of Kwinana Compost manufacturing and soil blending 14 Baldivis Landfill Facility City of Rockingham Class II or III putrescible landfill site 15 Biowise Town of Kwinana Compost manufacturing and soil blending 16 BP Refinery (Kwinana) P/L Town of Kwinana Oil or gas refining 17 Bradken Resources Pty Ltd City of Cockburn Scrap metal recovery 18 Brendon Pty Ltd T/A ABC Scrapmetal Town of Kwinana Scrap metal recovery 19 Chemeq Ltd City of Rockingham Chemical manufacturing 20 Ciba Specialty Chemicals Town of Kwinana Chemical manufacturing 21 Clean Drum Co WA Pty Ltd City of Cockburn Solid waste depot 22 Cockburn Cement - Kwinana Plant Town of Kwinana Cement or lime manufacturing 23 Cockburn Cement Limited City of Cockburn Cement or lime manufacturing 24 Cockburn No. 1 Power Station Town of Kwinana Electric power generation 25 Cockburn Receival Sales Depot City of Cockburn Compost manufacturing and soil blending 26 Coogee Chemicals Pty Ltd Town of Kwinana Chemical manufacturing 27 CSBP Limited Town of Kwinana Chemical manufacturing 28 Delvex Industrial Cleaning P/L City of Cockburn Liquid waste facility 29 Delvex Industrial Cleaning P/L City of Cockburn Liquid waste facility 30 Doral Specialty Chemicals Pty Ltd City of Rockingham Chemical manufacturing 31 DSL Drum Services (WA) Pty Ltd City of Cockburn Solid waste depot 32 Dunlop Flexible Foams City of Cockburn Foam products manufacturing 33 ELI ECO Logic Australia Pty Ltd Town of Kwinana Solid waste facility 34 Fremantle Port Authority Town of Kwinana Bulk material loading or unloading 35 Future Foams Pty Ltd City of Cockburn Foam products manufacturing 36 Garden Organics City of Cockburn Compost manufacturing and soil blending 37 Golden Ponds (WA) Pty Ltd City of Cockburn Aquaculture (ponds or tanks) Class I inert landfill site Class II or III putrescible landfill site 38 Henderson Landfill City of Cockburn Compost manufacturing and soil blending 39 HIsmelt Operations Pty Ltd Town of Kwinana Metal smelting or refining 40 Industrial Galvanizers (WA) City of Cockburn Metal finishing 41 Jandakot Sand Quarry City of Cockburn Screening, etc. of material 42 Jandakot Transfer Station City of Cockburn Solid waste depot 43 Jandakot Wool Washing Pty Ltd City of Rockingham Woolscouring
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44 KMK Cogeneration Facility Town of Kwinana Electric power generation 45 Kwinana Bulk Terminal Town of Kwinana Bulk material loading or unloading 46 Kwinana Cogeneration Plant Town of Kwinana Electric power generation 47 Kwinana Limestone Quarry Town of Kwinana Screening, etc. of material 48 Kwinana Power Station Town of Kwinana Electric power generation 49 Kwinana Wastewater Treatment Plant Town of Kwinana Sewage facility 50 Mephalene Rust Control (1995) Pty Ltd City of Cockburn Metal finishing 51 Millers Tyre Service (WA) City of Rockingham Used tyre storage (general) 52 Nalco Australia Pty Ltd Town of Kwinana Chemical manufacturing 53 Naval Base Zinc Electroplating Town of Kwinana Metal finishing 54 Nufarm Australia Limited Town of Kwinana Pesticides manufacturing 55 Nufarm-Coogee Kwinana Chlor-Alkali Plant Town of Kwinana Chemical manufacturing 56 OneSteel Trading Limited - Kwinana Works Town of Kwinana Metal finishing 57 Opal Chemical Technology Town of Kwinana Chemical blending or mixing 58 Point Peron WWTP City of Rockingham Sewage facility 59 Process Chemicals Town of Kwinana Chemical blending or mixing 60 Readymix Holdings - Swan Postans Quarry Town of Kwinana Screening, etc. of material 61 Reclaim Industries Limited City of Cockburn Used tyre storage (general) 62 Red Sands Supplies and Earthmoving Contractors Town of Kwinana Crushing of building material 63 Rocla Quarry Products City of Cockburn Screening, etc. of material 64 Rocla Quarry Products Town of Kwinana Screening, etc. of material 65 Rosguy Feedlot City of Rockingham Livestock saleyard or holding pen 66 Rottnest Island Landfill City of Cockburn Class II or III putrescible landfill site 67 Rottnest Island Wastewater Treatment Plant City of Cockburn Sewage facility Clay bricks or ceramic products 68 Shinagawa Refractories Australasia Pty Ltd Town of Kwinana manufacturing 69 Simsmetal Limited City of Cockburn Scrap metal recovery 70 Smorgon Steel Recyclers Town of Kwinana Scrap metal recovery 71 Supa Chips Pty Ltd City of Cockburn Food processing 72 Tenix Defence Pty Ltd City of Cockburn Boat building and maintenance 73 Terminals West City of Rockingham Solid waste facility 74 Tiwest Joint Venture Pigment Plant Town of Kwinana Chemical manufacturing 75 Unimin Australia Limited City of Cockburn Screening, etc. of material 76 United Farmers Cooperative Company Town of Kwinana Chemical blending or mixing 77 WA Limestone Co Town of Kwinana Screening, etc. of material 78 Waste Stream Management Town of Kwinana Class I inert landfill site 79 Wellard Rural Exports Pty Ltd City of Rockingham Livestock saleyard or holding pen 80 Wesfarmers LPG Pty Ltd Town of Kwinana Oil or gas refining 81 Western Power - Perron Quarry Town of Kwinana Fly ash disposal Processing or beneficiation of metallic or 82 BHP Billiton Kwinana Nickel Refinery City of Rockingham non metallic ore 83 Woodman Point WWTP City of Cockburn Sewage facility
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Appendix 3: Stakeholder Contacts The following table lists all stakeholders contacted as part of this study. This is not an exhaustive list of all stakeholders in the catchment – the goal was to gather information from a broadly representative sample of stakeholders. Not all stakeholders approached took the opportunity to contribute information or data to the study. Stakeholders in bold face operate licensed prescribed premises in the catchment. Responded to Date of # Stakeholder Request Hard/Soft Copy Response (yes/no)
1 Air Liquide WA (Australian Marine Complex) Yes 22/08/2005 Hard 2 Air Liquide WA Pty Ltd Yes 20/07/2005 Soft 3 Alcoa World Alumina Australia Yes 1/08/2005 Soft 4 Aussie Organics Garden Supplies Yes 17/10/2005 Phone 5 Australian Railroad Group Yes 18/08/2005 Hard 6 Austal Ships Yes 22/08/2005 Soft 7 Australian Fused Materials Pty Ltd Yes 21/07/2005 Soft 8 Australian Submarine Corporation (Tenix) No 9 Baldivis Landfill Facility (City of Rockingham) Yes 2/10/2005 Hard 10 Bayer CropScience Pty Ltd Yes 9/08/2005 Soft 11 Beurteaux Yes 15/08/2005 Hard 12 Boat Spray No 13 BOC Gases Yes 20/07/2005 Soft 14 BP Refinery (Kwinana) Yes 20/07/2005 Hard 15 Bradken Resources (Roche Castings) Yes 23/08/2005 Soft 16 BulkWest Yes 17/08/2005 Phone 17 CBI Constructors Pty Ltd Yes 21/07/2005 Phone 18 Chemeq Yes 16/08/2005 Soft 19 CIBA Specialty Chemicals Yes 3/08/2005 Soft 20 City of Cockburn Yes 7/07/2005 Hard 21 City of Rockingham Yes 1/09/2005 Phone 22 Cockburn Cement Ltd Yes 19/07/2005 Hard Cockburn Power Station (covered by
23 information from Kwinana Power Station) 24 Contract Marine Coatings Yes 19/08/2005 Phone 25 Coogee Chemicals Yes 20/07/2005 Soft 26 Co-operative Bulk Handling Ltd Yes 20/10/2005 Soft 27 CSBP Yes 13/07/2005 Soft 28 CWR - UWA Yes 21/06/2005 Soft 29 Delvex Industrial Cleaning Yes 19/08/2005 Phone 30 Dept of Defence Yes 21/06/2005 Soft 31 Dept of Health Yes 19/08/2005 Hard 32 Dept of Land Information Yes 7/09/2005 Hard+Soft 33 Dept of Planning & Infrastructure Yes 30/08/2005 Soft 34 Doral Speciality Chemicals Yes 9/09/2005 Soft 35 ELI Eco Logic No 36 ERM/GRC Yes 13/06/2005 Hard
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37 Flowtech Engineering Yes 17/11/2005 Soft 38 Fremantle Port Authority Yes 10/07/2005 Hard 39 Freo Machinery Yes 2/08/2005 Hard 40 Henderson Landfill (City of Cockburn) Yes 5/10/2005 Hard 41 HIsmelt Corporation Pty Ltd Yes 11/08/2005 Hard 42 Image Marine (Austal) Yes 22/08/2005 Soft 43 Key Group Engineering Yes 31/10/2005 Phone 44 Kwinana Cogeneration Yes 14/07/2005 Soft 45 Kwinana Transport Services No 46 Landcorp No 47 Madco Group No 48 Marine Interiors Pty ltd No 49 Millennium Chemicals Yes 13/10/2005 Soft 50 Nagata Australia Pty Ltd No 51 Nalco Australia Pty Ltd Yes 17/08/2005 Hard 52 Nufarm Coogee Pty Ltd Yes 18/07/2005 Hard 53 Nufarm Limited Yes 18/07/2005 Hard 54 Oceanfast Luxury Yachts (Austal) Yes 22/08/2005 Soft 55 One Steel Market Mills Yes 20/07/2005 Soft 56 Parsons Brinckerhoff Yes 5/08/2005 Hard 57 Recfishwest Yes 1/09/2005 Soft 58 SBF Shipbuilders No 59 Shinagawa Thermal Ceramics Aust P/L Yes 19/07/2005 Soft 60 Strategic Marine Pty Ltd No 61 Structural Marine Yes 18/10/2005 Hard 62 Summit Fertilizers Yes 10/08/2005 Hard 63 Tenix No 64 Terminals West Pty Ltd No 65 Tiwest Joint Venture Yes 19/08/2005 Hard 66 Town of Kwinana Yes 23/06/2005 Hard 67 Trailcraft Boats No 68 Tyco Water Yes 22/07/2005 Hard 69 United Farmers Cooperative Company Yes 29/07/2005 Hard 70 United KG Yes 4/08/2005 Soft 71 WA Vegetable Growers Association Yes 2/09/2005 Interview 72 Waste Stream Management Yes 23/09/2005 Hard 73 Water Corporation Yes 6/09/2005 Hard 74 Wellard Rural Transport No 75 Wesfarmers Kleenheat Gas Pty Ltd Yes 20/7/2005 Soft 76 Wesfarmers LPG Yes 20/07/2005 Soft 77 Western Power - Kwinana Power Station Yes 3/08/2005 Hard 78 WestNet Rail Pty Ltd Yes 17/08/2005 Hard 79 BHP Billiton Kwinana Nickel Refinery Yes 25/08/2005 Hard
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