VANCOUVER LAKE: DREDGED MATERIAL DISPOSAL AND RETURN FLOW MANAGEMENT IN A LARGE LAKE DREDGING PROJECT

Abstract

ABSTRACT The restoration of Vancouver Lake required the dredging of 6.5 × 106m3of material from the Lake, the construction of 17 km of land based retaining dikes to enclose 180 ha of disposal area, and the disposal of nearly 3 × 106m3of material in the lake to form an island. The requirement that all dredge return flow be returned to the lake necessitated careful control of dredging activity and the imposition of several design and operation features to control the quality of the return flow water. Some of the measures used included multiple, or settling basins, extended wier length to reduce crest height, silt curtain enclosures around dredge disposal site outfalls, rapid alteration of dredge disposal sites, and careful monitoring of dredging activity and return flow quality. These measures enabled the project to be completed with minimum delay, ahead of schedule, and with no serious violation of water quality standards. Observations and data on water quality conditions during construction and the effica...