A strategy for monitoring of contaminant distributions resulting from proposed sewage sludge disposal at the 106-mile ocean disposal site

Abstract

It has been proposed that future ocean disposal of sewage sludge from the US east coast be done at a site beyond the edge of the continental shelf. In anticipation of that, a monitoring strategy has been developed to determine the average spatial distribution of contamination. The strategy is an iterative series of measurements developed from models of sludge dispersion and settling which are based on characteristics of the disposal site and sewage sludge. Once disposal is initiated at the site, the strategy requires sampling the upper mixed layer at 36 stations, mostly within 100 km of the site, and deployment of near-bottom sediment traps along a line extending 300 km away from the site. Based on initial results, subsequent sampling locations will be selected to refine estimates of the detectable extent of sludge-derived contamination. The sludge constituents which can be used to detect sludge in water at a dilution of 10 6 and sludge in sediment traps when diluted by 100 with natural material include zinc, PCBs, coprostanol and spores of the bacterium Clostridium perfringens. Other synthetic organic compounds, besides PCB, may prove to be useful tracers.