As part of the ongoing remediation effort at the Hanford Site in Richland, Washington, the Envirocon team worked diligently to excavate chromium-contaminated soils at the 100-D waste sites in the D reactor area. With over 900,000 bank cubic meters of soil excavated at the 100-D-100, 100-D-104 and 100-D-30 waste sites, workers excavated what officials believe to be the primary source of chromium contamination to the Columbia River.

The 100-D Area houses two of Hanford’s nine reactors formerly used to produce plutonium for the nation’s defense program. From the 1940s to the 1960s, leaks or spills of sodium dichromate caused much of the chromium contamination in the D reactor areas. The substance was transported to the site via rail cars or trucks, transferred by underground piping, and added to the reactor cooling water during operations to inhibit corrosion of the piping system.

Crews chased chromium plumes by excavating to depths of 85 feet to reach groundwater and installing uniquely engineered ramps for transportation into and out of the excavation area. On the surface, the 100-D-30 and 100-D-104 sites merged to equal an area just over the size of seven football fields. At the bottom, the excavation was about the size of a single football field.
The most heavily contaminated material removed from the site was transported to the Environmental Restoration Disposal Facility (ERDF), a lined landfill located on the Hanford site. Some of this material had to be specially treated which meant it was mixed with cement to stabilize the chromium before final disposal at ERDF.

Protecting the Columbia River is one of the major goals of the ongoing remediation project at the Hanford Site, specifically in the 100-D Reactor Area. Chromium has the potential to cause cancer in humans and is toxic to fish and other aquatic life found in the river.

With the major removal of chromium-contamination near the D reactors, the team at Hanford is one step closer to achieving that goal. Remaining cleanup activities in the 100-D area include the load-out campaign currently scheduled for September 2014, backfill of the area