Design of a Permeable Reactive Barrier to Remediate Acidic Groundwater

Abstract

The Shoalhaven region of NSW experiences environmental acidification due to acid sulphate soils (ASS). In order to trial an environmental engineering solution to groundwater remediation involving a permeable reactive barrier (PRB), comprehensive site characterisation and laboratory-based batch and column tests of reactive materials were conducted. The PRB is designed to perform in-situ remediation of the acidic groundwater (pH 3) that is generated in ASS. Twenty-five alkaline reactive materials have been tested for suitability for the barrier, with an emphasis on waste materials, including recycled concrete, limestone, calcite-bearing zeolitic breccia, blast furnace slag, and oyster shells. Following three phases of batch tests, two waste materials (recycled concrete and oyster shells) were chosen for column tests that simulate flow conditions through the barrier and using acidic water from the field site (pH = 3). After 105 days in the column, the oyster shells still neutralised the water (pH = 7).