Acidic Groundwater Remediation in the Shoalhaven Floodplain

Acidic groundwater resulting from the oxidation of pyrite in acid sulfate soil (ASS) is a major geo-environmental problem in low-lying coastal regions. While the pyrite submerged is relatively inert, if exposed to atmospheric oxygen, it will rapidly oxidise to form sulphuric acid. This poses a serious challenge for floodplain management due to the catastrophic consequences associated with agriculture and aquaculture productivity, environmental damage to river ecosystems and acid damage to steel and concrete infrastructure. This paper reports the results of different methodologies adopted in the Shoalhaven floodplain (NSW, Australia) over two decades for remediation of acidic groundwater. Different approaches implemented over the years are compared in terms of their efficiency in halting pyrite oxidation and neutralizing the acidic groundwater and removing heavy metals, mainly dissolved Al and Fe resulting from the oxidation of the pyrite in the local acid sulfate soils.