Use of dredgings for landfill. Technical report no.4. Water quality study for a dredgings disposal area.

To quantitatively evaluate the effects of the settling-basin concept on the water quality associated with a typical disposal site for polluted maintenance dredgings, as well as to asses the fate of pollutants during a typical dredging and disposal cycle, and extensive sampling and testing program was carried out. Based on the measurements and analysis performed most of the polluting substances contained in the dredge spoil are retained in the diked enclosure, and only a small fraction of the pollutants are discharged via the over-flow weir into the ambient river water. The large reductions in the concentrations of pollutants is attributable to the fact that they tend to associate with the solid particles, which settle out of suspension and are retained within the disposal area. The more soluble substances were less affected by the settling process and they were discharged with less change in their input concentrations. (A)