ABSTRACT
At Kendall Bay in Sydney, the New South Wales Environment Protection Authority issued a sediment remediation declaration for a significantly contaminated area adjacent to a former gasworks facility. Today the disused industrial site has become a modern residential district. Therefore, not only the area on land was redeveloped but also the sediments in the bay. It was determined that remediation was required where the sediments contain total polyaromatic hydrocarbon (PAH) concentrations greater than 25 mg/kg on average and total recoverable hydrocarbon (TRH) of more than 4000 mg/kg on average. To remediate the highly contaminated sediments a subaqueous cap with an active geocomposite filled with activated carbon was built. This geotextile contaminant barrier adsorbs the organic contaminants before they can reach surface water due to diffusion and groundwater discharge. An accumulation of the pollutants in the water of the bay, the benthic and the aquatic organisms is thus prevented over several decades. In addition, the strong odor of organic contaminants is bound by the active geocomposite. The full-scale remediation work was completed from September 2019 until October 2020. In Kendall Bay, it was demonstrated that the installation process can be done quickly and in a variety of aquatic situations, including rivers, harbors, lakes, wetlands, etc.
