A Unique Hydraulic Dredge to Remove Organic Sediment from a Water Supply Reservoir

Abstract

The accumulation of a thin layer of organic sediment on the bottom of a large water supply reservoir posed a potential threat to water quality when strong wind-induced currents entrained sediment into the drinking water. A field test of a prototype dredge indicated that a hydraulic dredge head could be used to remove successfully the organic sediment from the bottom of the reservoir without creating a sediment plume, which would comprise water quality, and with minimal disturbance to the underlying granular layer that protects the clay liner. A series of laboratory experiments were subsequently undertaken to improve the sediment yield in the dredge discharge and thereby decrease the volume of dredge effluent requiring treatment.