To watch recordings of the June 20 or Sept. 26 presentations
about the Lot 46 Valley Gardens TCE Superfund Site, visit the Links tab on this page. The presentation
slides that were shown at the meetings are available under the Documents tab on this page.
The Lot 46 Valley Gardens Trichloroethylene (TCE) Superfund Site is a TCE-contaminated groundwater plume in Des Moines, Iowa. Investigations led by the Iowa Department of Natural Resources (IDNR) began in 2004, and the site was referred to EPA in 2020 for federal assistance. After monitoring the plume and observing its migration, EPA plans to propose the site to the National Priorities List in late 2023. Listing the site on the NPL will support long-term cleanup efforts, impede further plume migration, and prevent exposure to site contamination.
The site groundwater contamination plume extends northwest toward the Des Moines Water Works (DMWW) Fleur Drive Treatment Plant infiltration gallery. The infiltration gallery is a series of underground water collection pipes adjacent to the Raccoon River. Des Moines Water Works draws its water supply from a combination of both local groundwater and the Raccoon River. EPA is working with DMWW to sample water from along the infiltration gallery and the site groundwater monitoring well network to ensure that source water is of the highest quality.
Currently, TCE and its degradation products have not been detected in the infiltration gallery at concentrations exceeding safe drinking water standards. Additionally, TCE and its degradation products have not been detected at concentrations exceeding levels of ecological concern in site monitoring wells near the Raccoon River. Monitoring and investigation will continue. EPA has the authority to perform an immediate or short-term action at any time should data indicate an increased risk to the drinking water supply.
TCE and its degradation products in soil and/or groundwater may emit vapors. Based on current groundwater data, limited soil gas data, and the distribution of TCE and its degradation products in these samples, EPA has not identified a significant risk of exposure to such vapors at this time. However, investigation of vapor sources and pathways is ongoing.
