Under the order, Northrop Grumman will install wells and a treatment plant to contain and treat groundwater contaminated by volative organic compounds 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. Issued September 12, 2011. Additional information is available on the San Gabriel Valley Superfund site case summary web page.You may need a PDF reader to view some of the files on this page. See EPA’s About PDF page to learn more.