Following the July-August 2007 Lake Linden Emergency Response, U.S. EPA initiated a survey of the Torch Lake Area from the Quincy Smelter to the Gay Stampsand deposit. During the survey, the Mason Sands (AOI 10) was identified as having exposed stamp sands that contained elevated arsenic and drums that contained residual waste.
At the request of U.S. EPA's Remedial Branch, U.S. EPA's Removal Branch mobilized to the site on 11/17/08 and removed approximately 30 tons of arsenic-contaminated soil and 10 drums containing residual waste. The area from which contaminated soils were removed was backfilled with clean fill. Prior to backfill, U.S. EPA's FIELDS team conducted XRF screening at the base of the excavation; all arsenic levels were <5 ppm. Laboratory confirmation samples showed the highest level remaining before backfill was 1.6 mg/kg (1.6 ppm).
Final disposal occurred on December 11, 2008 with shipment of the wastes to Delta Solid Waste Management Authority.