Environmental Success: Accelerating Clean Up
SLAC's Environmental Restoration Group, a part of the Environment, Safety and Health (ES&H) Division, recently completed the installation and startup of an upgrade to the existing groundwater treatment and hydraulic containment system near the SLAC Paint Shop. This work, which was funded by Department of Energy's Office of Environmental Management, was previously announced in a January 2007 SLAC Today article.
The upgrade included the installation of a dual-phase extraction system that simultaneously extracts chemicals via both soil vapor and groundwater. The residual chemicals in the soil and groundwater near the Paint Shop originate from past leaks from a since-removed underground tank that held spent solvents (an accepted storage method at the time).
IIn addition, three new extraction wells were installed and the existing extraction wells and treatment system were retrofitted to accommodate vacuum application as part of the upgrade work. The application of a vacuum at the wellhead allows for the extraction of chemical-containing vapors residing within available soil pore spaces. It also increases the rate at which groundwater can be extracted and treated.
The original groundwater extraction system, constructed in 2001, was installed primarily to contain the contaminated groundwater plume and prevent its migration. This resulted not only in the successful containment of the plume, but also caused the plume to shrink. The upgraded system will shrink it even more rapidly, and with the addition of soil vapor extraction, the chemical mass removal rate has quadrupled.
So far, operation of the original and upgraded system has removed more than 600 pounds of chemicals from the subsurface and treated more than half a million gallons of groundwater.
"We're accelerating the removal process," Project Manager Elizabeth Dahlen said. "This project represents a significant accomplishment for the Department of Energy, SLAC and Stanford University."
Matt Cunningham, SLAC Today, April 15, 2008
Above image: Dwight Harbaugh, a member of the Environmental Restoration group, collects operating data.