The Dispersion and Detectability of Sanitary Waste-Water Discharges From Navy Ships

Abstract

Assessing the impact of Navy shipboard sanitary waste discharges within the contiguous zone of the United States requires generation of data, not available so far, on the dispersion and fate of pollutants from shipboard sources. To generate data applicable to the 3–12-mi coastal zone, studies were conducted by the Naval Ship Research and Development Center using Naval facilities in the Norfolk, Va. area. Controlled releases were made of sanitary waste water and tracer dye mixtures. Dispersion of waste/dye patches was monitored through aerial reconnaissance, precise radio-navigational information, and seawater sample collection. It was demonstrated that pollution from controlled releases of sanitary waste can be detected above background concentrations for a brief span of time using conventional methods for determining effluent water quality (5-day biochemical oxygen demand, total suspended solids, ammonia-nitrogen, total acid-hydrolizable phosphate, coliform bacteria). A mathematical model for the dispersion of pollutants discharged from ships in the coastal zone was developed from these data. An assessment was then made of the concentration of pollutants after discharge from Navy ships during normal operation. Seawater samples were collected from the wakes of ships in transit and from the water around ships anchored for an amphibious operation in the coastal zone. It was determined that pollutants discharged from the transiting ships were not measurable above background concentrations, and only slight coliform bacteria population increases were detected in the amphibious operations area. These increases were still well within those prescribed as safe for bathing beaches and fisheries. Findings of this study specifically refer to the Navy ships and the geographic locations involved. They may be used for estimating effects of sanitary waste releases by non-Navy ships and in other areas.