Active Geosynthetic Composites for Subaqueous Capping
Contaminated sediments are a significant and widespread environmental issue (1). Marine ports are always significant sources of environmental pollution due to the fact that their activities are associated with a particular contamination of aquatic areas and bottom sediment (2). Contaminants get into the aquatic environment through shipping traffic, loading, repairs, and dredging, as well as rainwater runoff, effluent discharge, dust, etc. (2) (3) (4). Former industrial sites that are out of service have already been recognized as potential threat to the environment. This resulted from a lack of knowledge and a lack of regulations regarding harmful substances in the past. Due to the need of water for the industrial processes many of these sites are located adjacent to rivers and lakes which resulted in a steady long term contamination of the waterbodies' sediments. Example sites are former wood treatment plants, gas plants, mining operations and paper mills. (2) (5) Different Technologies are currently used for addressing contaminated sediments including Monitored Natural Recovery (MNR), enhanced MNR (EMNR), in-situ capping, dredging or excavation and a combination of these approaches. These remedial options all have advantages and limitations for controlling human health and ecological risks associated with contaminated sediment. (1) The decision, which remedial technology should be used at a specific site, needs to be based on a risk assessment study.
The combination of geotextiles and active materials states an additional solution for all kinds of environmental engineering projects. The contaminant binding feature and the spectrum of active materials ranging from activated carbon, organophilic clay and zeolites to differentpolymers combined with the mechanical and chemical stability of geotextiles ensures an even broader field of application. Remediation of contaminated sediments using active géocomposite caps has been conducted successfully over the last years at different sites across the USA.