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  • Environment Protection Authority

    Lower Murray Reclaimed Irrigation Area (LMRIA) Acid Drainage Project

    Final summary report 2013

  • Lower Murray Reclaimed Irrigation Area (LMRIA) Acid Drainage Project: final summary report 2013

    This is a joint project between the South Australia Government and the MurrayDarling Basin Authority.

    Authors: Luke Mosley, David Palmer, Peter Mettam, Courtney Cummings and Emily Leyden

    This report was prepared as a summary of a project undertaken with the guidance of the LMRIA Acid Drainage

    Interagency Working Group comprising Andrew Beal (Chair, DEWNR), Richard Brown (DEWNR), David Cunliffe (DHA),

    Michael Cutting (SAMDB NRM Board), Rob Daly (SA Water), Jarrod Eaton (DEWNR), Jacqueline Frizenschaf (SA

    Water), Simon Gierke (PIRSA), Jessica Iacopetta (DEWNR), Thorsten Mosisch (SA Water), Rob Kingham (MDBA),

    Tapas Biswas (MDBA), Vladimir Tsymbal (SA Water), and Michelle Wittholz (DHA).

    For further information please contact:

    Information Officer

    Environment Protection Authority

    GPO Box 2607

    Adelaide SA 5001

    Telephone: (08) 8204 2004

    Facsimile: (08) 8124 4670

    Free call (country): 1800 623 445

    Website:

    Email:

    ISBN 978-1-921495-30-4

    July 2014

    © Environment Protection Authority

    This document may be reproduced in whole or part for the purpose of study or training, subject to the inclusion of an

    acknowledgment of the source and to it not being used for commercial purposes or sale. Reproduction for purposes other

    than those given above requires the prior written permission of the Environment Protection Authority.

    http://www.epa.sa.gov.au/ mailto:epainfo@epa.sa.gov.au

  • Contents

    Abbreviations ...................................................................................................................................................................... 1

    Acknowledgments ............................................................................................................................................................... 2

    Executive summary ............................................................................................................................................................. 3

    1 Introduction ................................................................................................................................................................... 4

    2 Key findings ................................................................................................................................................................ 10

    3 Communications and contingency plan ................................................................................................................... 24

    4 Management implications .......................................................................................................................................... 26

    5 Conclusion .................................................................................................................................................................. 28

    6 Recommendations ...................................................................................................................................................... 29

    7 References................................................................................................................................................................... 30

    List of figures

    Figure 1 Map of the acidic and neutral irrigation areas (swamps) and pump discharges in the LMRIA ............................ 5

    Figure 2 Lower Murray (Lock 1) river levels 1921 to 2012. ............................................................................................... 6

    Figure 3 Conceptual model constructed in 2011 by the EPA as basis for this project ...................................................... 7

    Figure 4 pH and acid base accounting data plotted against depth for each profile collected at Long Flat in 2011 and

    2012 ................................................................................................................................................................... 11

    Figure 5 pH in acid drainage plumes discharged from Jervois (Woods Point end) irrigation area in October 2011. ...... 12

    Figure 6 pH in acid drainage plumes discharged from Jervois (Woods Pt end) irrigation area in October 2011 ............ 13

    Figure 7 Relationships between dilution factor and change in dissolved metal (Al, Fe, Mn) concentration. ................... 14

    Figure 8 Concentration-response curves showing the toxicity of acid drainage water to cladocerans, shrimp and fish

    at two Jervois sites (Wellington and Woods Point) ............................................................................................ 16

    Figure 9 Soluble manganese (Mn) at the Tailem Bend SA Water offtake from the 3D geochemical model ................... 18

    Figure 10 Groundwater pH and acidity in piezometers in the B (0.75–1.25 m below ground level) and C (2.5–3 m

    below ground level) horizon at Long Flat ........................................................................................................... 20

    Figure 11 Lime slurry dosing at along the main drain at Jervois–Woods Point (left) and at the salt drain at

    Jervois– Wellington End (right) .......................................................................................................................... 20

    Figure 12 Modified mole plough attached to the rear of a tractor (left), excavation to show mole with injected lime

    (centre) and milk of lime in container with pump set-up at the front of the tractor (right). ................................. 21

    Figure 14 Management scenario showing how soil pyrite oxidation can be minimised by stabilisation of river levels

    at 0.5 m AHD and use of two environmental irrigations .................................................................................... 23

    Figure 15 The four-tiered alert system in the contingency plan ......................................................................................... 25

    Figure 16 Groundwater level at Mobilong and Mypolonga from 2002 to 2012 .................................................................. 27

  • 1

    0BAbbreviations

    ANZECC Australian and New Zealand Environment Conservation Council

    ASS acid sulfate soils

    DEWNR Department of Environment, Water, Natural Resources

    DHA Department of Health and Ageing

    EPA South Australian Environment Protection Authority

    LMRIA Lower Murray Reclaimed Irrigation Area

    MDBA Murray–Darling Basin Authority

    PIRSA Primary Industries and Regions South Australia

    SAMDB NRM South Australian MurrayDarling Basin Natural Resources Management Board

    WQG water quality guidelines

  • 2

    1BAcknowledgments

    This project was co-funded by the South Australian Government and the Murray–Darling Basin Authority (MDBA). The

    excellent project support and guidance from Rob Kingham and Brian Lawrence at the MDBA is gratefully acknowledged.

    The ongoing guidance and support of the LMRIA Interagency Working Group (individuals and agencies listed on inside

    cover of report) is also gratefully acknowledged.

    The cooperation and assistance of various irrigators and irrigation trusts across the LMRIA is greatly appreciated. In

    particular we would like to thank Barry and Joanne Pfeiffer at Long Flat for the use of their farm as an acid drainage

    management trial site and assistance with various aspects of the project.

    We also thank SA Water for offering their land at Mobilong for a trial of a novel lime injection remediation technique. The

    assistance of various SA Water staff is also much appreciated.

    We thank Michael Fogg for his contribution to this project while at the EPA.

    We would like to thank Drs Rob Fitzpatrick, Stuart Simpson, Anu Kumar, Merrin Adams, Paul Shand and Andrew Baker

    from CSIRO for contributing to the scientific understanding of the issue.

    We would also like to thank Dr Freeman Cook (Freeman Cook and Associates Pty Ltd) for assistance and advice on

    groundwater hydrological processes and calculations for Long Flat.

    Thank you to the Hon Dean Brown and the Lower Murray Sustainable Soils Reference Group for useful discussions and

    support for the project. The advice of Martin Philcox and Monique White is particularly acknowledged.

    Additional funding contributions from the Environment Protection Authority (EPA), SA Water and Primary Industries and

    Resources South Australia (PIRSA) are gratefully acknowledged.

  • 3

    2BExecutive summary

    Severe soil acidification occurred in the Lower Murray Reclaimed Irrigation Area (LMRIA) due to falling river and ground

    water levels, exposing acid sulfate soils during the extreme ‘millennium’ drought from 2007–10. The EPA became aware

    of this issue in February 2011 when unusual orange-brown water appeared in many LMRIA drainage channels. The

    LMRIA drainage water is returned to the River Murray via large pumps, a practice necessary to control saline water

    tables rise and

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