VGP Technical Report 23 - Groundwater sample collection and analytical methods for hydrochemical and dissolved gas analyses Onshore Otway Basin
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Product description:About the Victorian Gas Program: The Victorian Gas Program (VGP) is a comprehensive science-led program, incorporating geoscientific and environmental research to assess the risks, benefits and impacts of potential onshore conventional gas exploration and production. The program is also investigating the potential for further discoveries of onshore conventional and offshore gas in the Otway and Gippsland geological basins and assessing the feasibility of additional onshore underground gas storage in depleted reservoirs around the Port Campbell area. The VGP includes an extensive, proactive and phased community and stakeholder engagement program, through which the results of the scientific studies are being communicated. Executive summary: A regional assessment of groundwater chemistry, environmental isotopes, dissolved methane (CH4), and hydrocarbon occurrence has been conducted across the Otway Basin as part of the Victorian Gas Program (VGP). These baseline groundwater measurements were collected from State Government groundwater bores using low-flow sampling techniques. This baseline study is the most complete deep groundwater chemistry dataset collected in the Otway Basin by the Victorian Government to date, building on existing data and providing a baseline measure of groundwater conditions. As part of the VGP environmental studies program, the Geological Survey of Victoria (GSV) conducted baseline characterisation studies of the groundwater and atmosphere in the Victorian onshore Otway Basin to determine current environmental conditions. This groundwater chemistry dataset may support regulation of the sector by equipping government with a baseline it can use to monitor and report on any industry impacts. Groundwater is water that is stored in porous geological formations. Groundwater is more heavily relied upon than surface water in many parts of the world and is a key source of drinking water in many places in Australia. To protect groundwater from contamination and overuse, it is important to understand how water gets underground, how it flows through the subsurface geology, and how long it remains underground. Hydrogeologists use geochemical methods to characterise groundwater quality and understand local and regional groundwater processes (such as where the water has come from and how long ago). Results for this project may be used by groundwater users, industry, water suppliers and regulators. This report presents detailed field sampling and laboratory analysis methods for all groundwater samples collected in the Otway Basin. This includes field stabilisation data, which ensured water collected was representative of the aquifer, rather than stagnant water from the bore column. The groundwater sampling equipment and methods used here are common to many groundwater geochemical studies conducted in Australia and internationally. In total, 81 groundwater samples were collected across the Otway Basin covering a depth range of 8 m to 1500 m. Of these 81 samples, 73 were collected from groundwater bores that are part of the Victorian Government State Observation Bore Network (SOBN) and eight were collected from town water supply bores. Each groundwater sample was analysed for 144 analytes. A regional baseline of the groundwater chemistry (Iverach et al., 2020) and detailed geochemical interpretations (Iverach et al. in prep.) are presented in separate technical reports. Bibliographic reference: Iverach, C.P., Bold, T.A., O’Neill, C. & Hocking, M., 2020. Groundwater sample collection and analytical methods for hydrochemical and dissolved gas analyses Onshore Otway Basin, Victoria. Victorian Gas Program Technical Report 23. Geological Survey of Victoria. Download: The downloadable version of this report is supplied in PDF format (43.1 MB) & accessible version (DOCX 27 MB). Related products:
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