Fort Lewis

Project Summaries


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9722-9F5 - Assessment of the Ground-Water Flow System and Potential Remediation of the Logistics Center, Fort Lewis, Washington - Completed FY2006

Problem - Fort Lewis is a 135-square-mile U.S. Army post in Pierce County, Washington, located just south of Tacoma. The Environmental and Natural Resources Division of Fort Lewis wishes to evaluate the effectiveness of the current and potential remediation activities at the Logistics Center, a regional maintenance facility at Fort Lewis where pump-and-treat systems are being used to remediate chlorinated volatile organic compounds (VOCs), especially trichloroethylene (TCE), in the ground water. To do this, the Army needs to better understand the local and regional ground-water flow systems at the site, and the relation between the two. The present and historical distributions of the contaminants of concern, especially the TCE, also need to be known. This information will also be needed to support evaluations of the potential for other remedial activities, such as natural or assisted biodegradation, that might accelerate the remediation of the site.

Objectives - The Army has requested that the U.S. Geological Survey (USGS) (1) provide technical asistance to Fort Lewis and the Army Corps of Engineers in developing and implementing effective remediation strategies for TCE in ground water at Fort Lewis, and (2) conduct an investigation of hydrology and contaminant fate and transport in the lower aquifer beneath Fort Lewis.

Relevance and Benefits - Investigations conducted as part of this project add to the current understanding of ground-water remediation techniques used to treat ground water contaminated with chlorinated volatile organic compounds. This work is relevant to enhancing partnerships and working relationships with other Federal agencies, private scientific agencies, and universities.

Approach - Each year, the USGS and Fort Lewis prepare an annual workplan for technical oversight and investigation activities stating the anticipated costs of fulfilling each request and a time schedule for same. Completed technical reviews are provided to the Army as official correspondence. A more detailed proposal for the lower aquifer investigation was originally prepared in 2000 and is amended annually as needed. The lower aquifer investigation approach relies primarily on the use of environmental tracers to determine ground-water flow and contaminant fate and transport characteristics, and the connectivity and contaminant transport between the upper and lower aquifers. Preliminary investigation results are provided to the Army in regular status reports, and final results will be provided as a formal USGS report.