A synopsis of potential amendments and remediation techniques for the neutralization of acidic drainage waters in the Western Australian Wheatbelt ; a technical report prepared for the Engineering Evaluation Initiative (EEI) and the Wheatbelt Drainage Evaluation Project, both commissioned as part of the National Action Plan for Salinity and Water Quality (NAPSWQ)
Executive Summary: Within the wheatbelt of Western Australia (WA) salinised land has the potential to increase to over 3 million hectares.The main engineering option of choice has been the use of over 10,000 km of deep (2-3m) open drains, which are increasingly being used to protect low-lying land from salinisation and rehabilitate marginally saline lands.The prospect of increasing volumes of effluent produced by deep drains has increased concerns about the acidic, trace element rich waters that can be produced by such drainage systems and the impacts of these on receiving environments.A multi-agency research project involving CRC-LEME, CSIRO Land and Water, the Department of Water and the Department of Agriculture was launched in 2004 to quantify the geochemical risks associated with conducting deep drainage at regional scales to control rising saline water-tables in the Avon Basin.The objectives of this study were to: *Understand the processes of acidic groundwater in the natural or pre-disturbance regolith, and later, beneath the a cleared landscape, *Forecast the impacts of engineering drainage on the transport and transformation of trace elements in undrained and drained environments, and *Identify feasible management options (opportunities and constraints) for dealing with the geochemical risks.This project was initiated to support an Engineering Evaluation Initiative (EEI) funded CSIRO Land and Water project evaluating regional drainage options for the Avon catchment.In light of the above, challenges exist to identify methods:(i)for remediation of the acidic groundwater that are environmentally robust in terms of the safe and efficient immobilization (and if appropriate, disposal) of the contaminants after neutralization,(ii)for long-term management of the site(s) as required to meet regulatory requirements,(iii)that are easily applied, gain statutory approval and wide community acceptance and are easily integrated into the WA wheatbelt environment, and (iv) that are cost effective on both a local and regional scale. These first three challenges form the basis of this brief scientific literature review of potential amendments and techniques for the neutralization of acidic waters in the WA wheatbelt.A synopsis of each amendment or technique is presented, as well as perceived advantages and disadvantages.The amendments and techniques presented in this report are as follows:*Carbonates/carbonate derivatives *Mineral processing by-products *Mine overburden *Alkalinity producing systems *Alkaline waters *Landscape modification (burial, re-flooding) Cost is not specifically considered in this review due to the potential for wide variation in terms of factors such as transport, infrastructure requirements and running costs for different techniques at specific sites.
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