Environmental Impact Assessment of Lake Menindee Shallow Aquifer Test Bores October 2015
Environmental Impact Assessment of Lake Menindee Shallow Aquifer Test Bores WaterNSW on behalf of the NSW Government is currently undertaking a drilling project on the bed of Lake Menindee. The purpose of the project is to assess the quantity and quality of water available in the shallow aquifer beneath the dry bed of the Lake to determine its suitability as an emergency water supply for Menindee, Sunset Strip and Broken Hill. If it is suitable any water extracted from this shallow aquifer would need to be treated by Essential Water to ensure it meets the Australian Drinking Water Guidelines. This would ensure the water is safe to drink. Prior to commencing the drilling an environmental impact assessment was undertaken in accordance with the Environmental Planning & Assessment Act, 1979. The environmental impact assessment document was prepared consistent with the Proponents Guidelines for the Review of Environmental Factors, Department of Environment, Climate Change and Water (February 2011). The environmental impact assessment document was prepared by consultants GHD on behalf of WaterNSW. The objective of the environmental impact assessment was to avoid impacts and where impacts could not be avoided to minimise them and to propose specific measures to mitigate these remaining impacts. WaterNSW consulted with the NSW Office of Environment and Heritage, Environment Protection Authority and NSW Fisheries when preparing the environmental impact assessment document and advice received from these agencies was addressed. Consultation also occurred with the Aboriginal community. The environmental impact assessment document assessed impacts associated with the drilling and testing of 17 bores. WaterNSW has made the decision not to proceed with one of the bores as it was close to a known Aboriginal cultural heritage site. Two bores assessed and located on land to the immediate north of the bed of Lake Menindee will also not be drilled at this stage. The fourteen bore holes to be drilled are GT03, GT04, GT06, GT07, GT08, GT09, GT10, GT11, GT12, GT13, GT14, GT15, GT16 and GT17 and are shown on Figure 1.1 below. None of these bore holes are located in the Kinchega National Park. At each of the bore sites an initial pilot bore is drilled and tested. If the results from a pilot bore indicates water is of a suitable quantity and quality, a further larger sized bore is drilled and this bore is pump tested for 7 days. Two small monitoring bores are drilled in close proximity of the larger sized bore to monitor groundwater level and quality during the pumping test. The bores are drilled in accordance with the Minimum Construction Requirements for Water Bores in Australia, published by the Australian Drilling Association. The pumping testing is undertaken to comply with the Australian Standard AS 2368 1990 Test Pumping of Water Wells. The bores are drilled using a mud rotary method to a maximum depth of up to 60 metres in the Calivil Formation and groundwater is expected to have a salinity level of 500 to 1000 Electrical conductivity units (ECS). Many people can taste salt in water at 1,500 to 2000 ECs and sea water is approximately 50,000 ECs. The environmental impact assessment document describes the existing environment at each of the drill sites and more generally within the locality. The environment at each of the sites to be drilled 1
on the bed of Lake Menindee is relatively consistent at each site. Each site is relatively level and flat with clayey soils. The vegetation community at each site is a dry lakebed herbfield/grassland/sedgeland. While the Menindee Lakes are known to provide habitat for a number of threatened species listed under Commonwealth and State legislation, the only species identified to be at possible risk of impact from the proposal is the Menindee Nightshade. This species is listed as Vulnerable at both Commonwealth and State level. Menindee Nightshade is a small grey green downy forb with purple flowers. No Aboriginal cultural heritage sites were found on the bed of the Lake at the proposed drill sites. Having regard for existing environment and the proposed drilling and testing an environmental impact assessment was undertaken which assesses the potential environmental impacts likely to occur as a result of the proposal. The outcomes from this assessment are summarised below: The following potential impacts were assessed physical and chemical, biological, community, natural resources, Aboriginal cultural heritage and matters of national environmental significance under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999. Physical and chemical impacts the following physical or pollution impacts have the potential to impact on the environment: soil erosion from construction activities including drilling, excavation, and the movement of construction vehicles soil contamination from spillage of oils and fuels, waste generation including general waste and construction waste sedimentation and contamination of water catchments from occurrences such as drilling fluid seepage, spillage of liquid wastes, oils and fuels, and dust generation water quality impacts due to the discharge of groundwater The extent of physical or pollution impact would be minimised by implementing the following mitigation measures: work areas at each drill site are to be limited to a 50 metre by 50 metre pad and all activities are to be restricted to this pad including the storage of equipment, stockpiles and pits works are to be suspended if it is likely that rainfall is predicted that would cause drill sites and access to be flooded or if the movement of vehicles would create boggy ground the quantity of chemicals including fuels stored at each drill site will be minimised, relevant Material Data Safety Sheets will be available at each site, and chemicals will be stored in bunded areas the discharge point of test waters will be located to avoid areas where flows will be concentrated during storm runoff events and energy discharge measures will be located at discharge points drilling fluids/muds will be recycled in lined pits spill response kits are to be available at each drill site 2
all waste materials will be removed from each drill site and disposed of at appropriate locations each drill site is to be rehabilitated The implementation of these mitigation measures should result in any residual impact being negligible. Biological impacts the following biological impacts have the potential to impact on the environment: minor vegetation removal impacts to flora and fauna through the introduction of weeds, vermin and feral species into the area through construction machinery The extent of physical or pollution impact would be minimised by implementing the following mitigation measures: minimising the clearing of vegetation by keeping to the minimum the number of vehicular tracks on the lake bed and restricting work areas at each drill site drilling machinery entering the lake bed will be thoroughly cleaned to remove weed seeds and other plant parts as well as soil that may contain seeds and other plant propagules Biological Community Natural resources Aboriginal cultural heritage Matters of national environmental significance under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999. 3
In response to this assessment of potential impacts a range of mitigation measures are proposed in the environmental impact assessment document and all these have been adopted by WaterNSW. These measures address general matters, soils, surface and ground water, hazardous substances and chemicals, waste management, air quality, noise, flora and fauna, traffic, social and community, hazards and risks, Aboriginal heritage, and non Aboriginal heritage. As Aboriginal cultural heritage and threatened species were key issues identified during the assessment process they were assessed in detail. Threatened species assessment of significance (7 part tests) were carried out for Menindee Nightshade, Silver Perch, the Darling River Endangered Ecological Community and the Murray Cod. These threatened species assessments concluded that the project was unlikely to have a significant impact on these species and community. A specialist consultant with expertise in assessing Aboriginal cultural heritage impacts was engaged to carry out this assessment. This assessment was carried out consistent with guidelines published by the NSW Office of Environment and Heritage. This assessment was carried out in close consultation with the local Aboriginal community and involved representatives of the community in on ground site surveys. This assessment concluded that the project was unlikely to impact Aboriginal cultural heritage sites providing specific measures are adopted. WaterNSW has agreed to all these measures. The environmental impact assessment document concluded that the drilling project was not likely to significantly affect the environment subject to implementation of the recommended mitigation measures and therefore an Environmental Impact Statement was not required. 4
The environmental impact assessment document was formally determined by WaterNSW and specific conditions set. A condition required the preparation of a construction environmental management plan by the drilling contractor. This plan was prepared and subsequently endorsed by WaterNSW. The current drilling is therefore operating consistent with: the description contained in the environmental impact assessment document including the range of mitigation measures detailed in the document the environmental impact assessment document approval conditions the construction environmental management plan. The environmental impact assessment document does not assess the impacts of using the test bores for extraction of water to supply local communities including Broken Hill. The environmental impact assessment document only assesses the impact of drilling and testing bores. Should WaterNSW decide to proceed with using the test bores for extraction of water (known as a production borefield) to supply local communities an additional environmental impact assessment document will be prepared. This additional environmental impact assessment document would assess the impacts of construction, operation and decommissioning of a production borefield. 5