SEATTLE – 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.
This week Corps representatives are going door-to-door asking for access to about 35 new private drinking water wells in Cascade Valley. Simultaneously rights-of-entry for 68 monitoring wells are being reestablished. Later Corps officials will schedule sampling work with each well owner.
The majority of Moses Lake residents get their drinking water from the City of Moses Lake or a community system which is tested regularly to ensure it meets 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.
The groundwater contamination is from operations on the old Larson Air Force Base and Grant County Airport where an industrial solvent, trichloroethylene (TCE), was used for cleaning and stripping aviation parts. As a result, deep beneath the soil are two TCE-contaminated groundwater plumes located under the former air base property.
“We are sampling the monitoring wells this year to see if the groundwater plumes are moving, if conditions have changed and what types of contaminants are present,” said Dan Sacks, Corps project manager for the effort.
Sacks added that information gathered from monitoring wells will be incorporated into a pump-and-treat system the EPA is designing. By next year, the EPA plans to have a design completed for installation of extraction wells and will start the groundwater treatment system soon after.
Corps representatives will start sampling well water in May and will have results available to the public around September 2013.
While annual testing of private wells has been ongoing for more than a decade, this year the Corps expanded sampling to include 35 new wells. If contaminants are detected above standards for drinking water, whole-house filtration systems will be installed to remove TCE.
“If you are on city water, you are unaffected as this only applies to those with private wells,” Sacks said. “Our goal is simple: Make sure the water is healthy and safe to use.”