Groundwater Impact Assessment – Conceptual Report Onshore Otway Basin, Victoria
Total Page:16
File Type:pdf, Size:1020Kb
VICTORIAN GAS PROGRAM Groundwater impact assessment – Conceptual report Onshore Otway Basin, Victoria S. Torkzaban, M. Hocking, A. Gaal, S. Manamperi & C.P. Iverach Victorian Gas Program Technical Report 34 September 2020 Authorised by the Director, Geological Survey of Victoria Department of Jobs, Precincts and Regions 1 Spring Street Melbourne Victoria 3000 Telephone (03) 9651 9999 © Copyright State of Victoria, 2020. Department of Jobs, Precincts and Regions 2020 Except for any logos, emblems, trademarks, artwork and photography this work is made available under the terms of the Creative Commons Attribution 3.0 Australia licence. To view a copy of this licence, visit creativecommons.org/licenses/by/3.0/au. It is a condition of this Creative Commons Attribution 3.0 Licence that you must give credit to the original author who is the State of Victoria. This document is also available in an accessible format at www.djpr.vic.gov.au Bibliographic reference TORKZABAN, S., HOCKING, M., GAAL, A., MANAMPERI, S. & IVERACH, C.P., 2020. Groundwater impact assessment - conceptual report, onshore Otway Basin, Victoria. Victorian Gas Program Technical Report 34. Geological Survey of Victoria. Department of Jobs, Precincts and Regions. Melbourne, Victoria. 94p. ISBN 978-1-76090-385-5 (pdf/online/MS word) Geological Survey of Victoria Catalogue Record 161884 Key Words conceptual model, gas, groundwater, Otway Basin, water balance Acknowledgements The CAT3D recharge model was provided by Craig Beverly (Agriculture Victoria). Bore hydrographs were developed by Tiffany Bold, and Cassady O’Neill and Josh Grover provided gas/groundwater volumetric production calculations and potentiometric surface maps. Karsten Michael, Praveen Rachakonda and Paul Wilkes (CSIRO) provided review comments and Randal Nott (DELWP) reviewed the report. Leisa McCartney edited the final report, Luong Tran compiled the maps and Allyson Crimp designed the final report 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. About the Geological Survey of Victoria The Geological Survey of Victoria (GSV) is the Victorian Government’s geoscience agency and sits within the Department of Jobs, Precincts and Regions. GSV provides evidence-based knowledge and information to Government, industry, academia and the community, on Victoria’s earth resources, using the latest geoscience technologies and methods. For more details visit earthresources.vic.gov.au/gsv Disclaimer This publication may be of assistance to you, but the State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication. The Victorian Government, authors and presenters do not accept any liability to any person for the information (or the use of the information) which is provided or referred to in the report. Table of contents Table of contents ................................................................................................................................................. iii List of figures ......................................................................................................................................................... iv List of tables ........................................................................................................................................................viii Summary................................................................................................................................................................. ix 1 Introduction ...................................................................................................................................................... 1 1.1 Victorian Gas Program ..................................................................................................................................1 1.2 Developing the South-West region groundwater model ....................................................1 2 Regional setting ..............................................................................................................................................3 2.1 Study area ...............................................................................................................................................................3 2.2 Climate .......................................................................................................................................................................5 2.3 Topography ............................................................................................................................................................7 2.4 Geology ......................................................................................................................................................................8 2.5 Soils ...............................................................................................................................................................................9 2.6 Land use ................................................................................................................................................................. 10 2.7 Flooding ....................................................................................................................................................................11 2.8 Land salinisation ...............................................................................................................................................11 3 Hydrogeological setting ............................................................................................................................13 3.1 Structural geology ..........................................................................................................................................13 3.2 Hydrostratigraphy, significant aquifers and aquitards ....................................................16 3.3 Groundwater level trends ........................................................................................................................ 22 3.4 Groundwater trends of the Port Campbell Embayment ............................................... 43 3.5 Groundwater pumping .............................................................................................................................. 50 3.6 Groundwater recharge ..............................................................................................................................52 3.7 Surface water and groundwater interactions .........................................................................53 3.8 Density corrections for salinity and temperature ...............................................................56 3.9 Conceptual groundwater model ........................................................................................................57 4 Conclusions ....................................................................................................................................................59 References ............................................................................................................................................................ 60 Glossary .................................................................................................................................................................64 Abbreviations and units .................................................................................................................................65 Appendix A1 Extent and thickness of model layers ...........................................................................66 Appendix A2 Potentiometric surface contours for model layers ................................................ 74 Appendix A3 Calculation of groundwater pumping from historical gas production .........83 Appendix A4 Slug testing of UMTA and LTA ...........................................................................................86 Attachment A1 Complete geochemical dataset List of figures Figure 2.1 Onshore conventional gas program study area and South-West region groundwater model extent. ...........................................................................................................................3 Figure 2.2 Surface water catchments, major streams, lakes and soil salinity areas. ..............4 Figure 2.3 Groundwater Management Areas in the south west region. .............................................4 Figure 2.4 Distribution of mean annual rainfall across the south west region (1950–2017) (BOM, 2018). ....................................................................................................................................................5