Isolation Layer Enables Lake Ecosystem Rehabilitation

Machado Lake is highly contaminated with toxic sediments containing DDT, PCBs, and heavy metals. The primary goal of the remediation project is to improve water quality in the 45-acre lake while enhancing the natural habitat and providing new recreational opportunities. To accomplish this, a low-permeability AquaBlok layer is being used to sequester and isolate residual contaminants. This allows for the establishment of a clean layer to support benthic recover and restoration.

The project uses a dredge and cap approach to isolate residual contamination in the sediments after dredging. A hydraulic dredge will remove approximately 239,000 cubic yards of contaminated sediments. Following dredging, the lake bottom is to be capped with an approximate 6-inch thick AquaBlok layer. The project will require over 33,000 tons of AquaBlok 2080FW to form the isolation capping layer. The AquaBlok layer will then be covered with materials to enhance habitat recover. The $111-million project, funded by California Proposition-O, is scheduled to be completed by spring 2017.

Photo courtesy of the City of Los Angeles, Department of Public Works.

Watch the Lake Machado Rehabilitation project update from the Los Angeles City Council here.