This Superfund site sits in West Des Moines, Iowa and centers on contaminated groundwater beneath 22 municipal water supply wells. It was discovered in 1993 when cis-1,2-dichloroethene turned up in a water sample. EPA added the site to the National Priorities List in December 2002 and split it into operable units to manage cleanup. Construction of the cleanup was completed in August 2007, and the site reached sitewide readiness for anticipated reuse in April 2018.
Two separate groundwater plumes carry the contamination. The north plume contains chloroethene (vinyl chloride), cis-1,2-dichloroethene, tetrachloroethene, and trichloroethene. The south plume contains cis-1,2-dichloroethene, tetrachloroethene, trans-1,2-dichloroethene, and trichloroethene. These volatile organic compounds are the contaminants of concern. The south plume traces back to a release of trichloroethene at a former metal brazing facility. The source of the north plume has not been identified despite extensive investigations.
Cleanup has moved through several phases. Early actions included upgrading aerators at the water treatment plant to strip contaminants and keep metals out of the public water supply. Those aerators were retrofitted to a slat-style design in 2015 for cost savings. An air-sparging system ran until 2009, when the approach shifted to monitored natural attenuation for both plumes. Routine groundwater sampling continues to confirm that contaminants are breaking down. Polk County and the Iowa Department of Natural Resources enforce well-permitting rules that limit private groundwater use. Iowa law requires a permit before any well can be built or rebuilt, and Polk County checks with state regulators before issuing one to make sure the proposed location is not in a contaminated zone.
EPA completed its third Five-Year Review in August 2021 and found that remedies at both plumes are currently protective of human health and the environment. Human exposure is under control, and groundwater migration is stabilized within the original contamination area with no unacceptable discharge to surface water. The next five-year review is estimated for August to October 2026. One business currently operates on site, employing 10 people and generating about $1.99 million in annual sales revenue.
Community members with questions can contact EPA's Community Involvement Coordinator. Site records are available for public review at the West Des Moines Public Library at 4000 Mills Civic Parkway, West Des Moines, Iowa 50265, and at the EPA Region 7 Records Center in Lenexa, Kansas.
