USGS Washington Water Science Center
|U.S. Department of the Interior
U.S. Geological Survey
Release: May 31, 2002
253-428-3600, ext. 2603
Natural cleaning processes are an important part of the U.S. Navy's cleanup of chlorinated solvents in ground water at the Naval Undersea Warfare Center at Keyport, Washington, according to a report released today by the U.S. Geological Survey (USGS), in cooperation with the Navy.
Natural processes can reduce, or attenuate, the level of contaminants in ground water. Contaminants can be broken down by microbes and chemical reactions, or trapped by sticking to soil particles. Scientists monitor the conditions to make sure that natural attenuation is reducing contaminant levels. Monitored natural attenuation can be an effective tool in ground- water cleanup.
At Keyport, chlorinated solvents including trichloroethene (TCE), cis-1,2-dichloroethene (cisDCE), and vinyl chloride (VC), have migrated into the shallow and intermediate aquifers below the former landfill, uphill from a marsh. Natural attenuation is helping to remove those contaminants from ground water.
"We have seen that natural attenuation has substantially reduced the contaminants in the shallow ground water," said USGS hydrologist Rick Dinicola, lead author of the report. "About 70 percent of the contaminants are broken down in ground water before they have a chance to reach the marsh."
To further help remove contaminants, poplar trees have been planted by the Navy in two areas on the landfill site. The poplar trees will eventually draw up contaminants, breaking them down and trapping them within the plants.
"The trees are still young and not yet effective at removing contaminants," Dinicola said, "but they should eventually work very well in combination with natural attenuation. The USGS and the Navy will continue monitoring the site to assure that the trees and natural attenuation are working together."
The report, "Natural Attenuation of Chlorinated Volatile Organic Compounds in Ground Water at Operable Unit 1, Naval Undersea Warfare Center, Division Keyport, Washington," by R.S. Dinicola, S.E. Cox, J.E. Landmeyer, and P.M. Bradley, is published as U.S. Geological Survey Water-Resources Investigations Report 02-4119. Copies can be purchased from the U.S. Geological Survey, Information Services, Box 25286, Federal Center, Denver, CO 80225-0286, telephone 303-202-4200. It can also be viewed on the Web at http://pubs.water.usgs.gov/wri024119.
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