Case Summary: EPA issues Order for San Gabriel Valley Superfund Site Area 4 - Puente Valley
On September 13, 2011, EPA ordered Northrup Grumman Systems Corporation to spend an estimated $20 million to build a groundwater cleanup system to address contamination stemming primarily from the former Benchmark Technology facility in the City of Industry, CA, located within the San Gabriel Valley Superfund Sites.
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Founded in 1939, Northrop Grumman Systems Corporation designs, develops, and manufactures various defense electronics and systems and is located in Los Angeles, CA. Northrup Grumman, through its predecessor TRW, Inc., owned and operated the Benchmark facility from approximately 1968 to 1983.
The San Gabriel Valley Area 4 site is an area of contaminated groundwater that runs along San Jose Creek in La Puente. This site is one of four Superfund sites located in the 170-square-mile San Gabriel Valley. The EPA listed several sections of the San Gabriel Valley as Superfund sites in 1984. More than 30 square miles of groundwater under the Valley may be contaminated. The contaminated groundwater associated with all of the San Gabriel Valley sites lies under significant portions of Alhambra, Irwindale, La Puente, Rosemead, Azusa, Baldwin Park, City of Industry, El Monte, South El Monte, West Covina, and other areas of the San Gabriel Valley. There are 45 water suppliers in the Valley that use the San Gabriel Basin groundwater aquifer to provide 90 percent of the drinking water for over one million people.
More information on the San Gabriel Valley Superfund Site, Area 4 Puente Valley.
Groundwater and soil are contaminated with various VOCs. The primary VOC contaminants are trichloroethylene (TCE), perchloroethylene (PCE), and 1,4-dioxane. Low levels of perchlorate have also been detected. People who inhale vapors from groundwater that contain VOCs could be exposed to hazardous substances.
Under the order, Northrop Grumman will install wells and a treatment plant to contain and treat groundwater contaminated by VOCs and 1,4-dioxane. The treated water will then be discharged back to surface water or injected back into the underground aquifer, providing additional water resources to San Gabriel Valley residents. The September order will protect the essential drinking water supplies in the San Gabriel Valley. The treatment system is designed to intercept the most highly contaminated groundwater plume and prevent it from migrating further.
For more information, contact:
U.S. Environmental Protection Agency
1200 Pennsylvania Ave, NW (MC 2272A)
Washington, DC 20460