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Posted 4/16/2015

Release no. 15-009


As part of the Environmental Protection Agency’s long-term effort to clean contaminated groundwater and soil at the Moses Lake Wellfield Superfund site, U.S. Army Corps of Engineers’ officials are planning to test groundwater samples at a mix of monitoring and private drinking water wells this spring.

The groundwater contamination is from operations on the old Larson Air Force Base and Grant County Airport where trichloroethene (TCE) was used as an industrial solvent for cleaning and stripping aviation parts.  As a result, two TCE-contaminated groundwater plumes are located under the former air base property.

The Corps samples the monitoring wells to see if the groundwater plumes are moving, if conditions have changed, and what types of contaminants are present. In addition, data gathered from the monitoring wells will be incorporated into a groundwater pump-and-treat system the EPA is designing. 

Most residents get their drinking water from the City of Moses Lake or community systems, which are tested regularly to ensure they meet Safe Drinking Water Act standards.  However, small water systems and other private wells are not required to be tested.  The Corps is focusing on these small water systems and private wells located near contaminated groundwater.  For the past several years, all wells that were tested for TCE in Cascade Valley have met safe drinking water standards.

While annual testing of private wells has been ongoing for more than a decade, the Corps increased sampling to quarterly monitoring at properties where there is a risk of exceeding Safe Drinking Water Act standards.  If contaminants are detected above a certain threshold for drinking water, then whole-house filtration systems will be installed to remove TCE so concentrations do not exceed the Safe Drinking Water Act standards.

Corps representatives will start sampling in May and anticipate having results available to the public in early 2016.