This site is an unincorporated residential area about 25 miles southwest of St. Louis. In the early 1970s, oil contaminated with dioxin (specifically 2,3,7,8-tetrachlorodibenzo-p-dioxin, or TCDD) was sprayed at the Bubbling Springs Ranch horse arena to control dust. Contaminated soil from that arena was later spread as fill in nearby residential areas. EPA added the site to the National Priorities List (NPL) in September 1983, which triggers formal investigation and cleanup under the federal Superfund program.
TCDD is the only contaminant of concern identified at the site. It has been found in soil across multiple parts of the site and in both soil and sediment in the Romaine Creek area. Because of these risks, EPA permanently relocated 11 families from the Minker and Stout portions of the site. From 1985 to 1989, crews excavated roughly 26,420 tons of contaminated material and sent it to the Times Beach incinerator for thermal treatment. Most soils above one part per billion (ppb) were removed to a depth of four feet or down to bedrock. One area in the Minker section still has residual dioxin as high as 266 ppb at four feet deep. That area is covered with clean backfill and marked with permanent survey markers. The Minker parcel is registered on the Missouri Department of Natural Resources' Abandoned and Uncontrolled Hazardous Waste Disposal Sites Registry, which requires annual state inspections and a deed notice on file.
Construction of the cleanup was completed by September 30, 1997, and the site reached "sitewide ready for anticipated reuse" status on June 26, 2006. The site has been restored as a residential area. However, it has not yet been deleted from the NPL. Because hazardous substances remain on-site above levels that allow unrestricted use and unlimited exposure, EPA is conducting its first Five-Year Review. Samples were collected between February and March 2025, and EPA released a data evaluation report in November 2025. The full Five-Year Review report is expected by September 30, 2026.
Community members who want to stay involved can contact EPA's Community Involvement Coordinator. A public notice with more information is also available through EPA's Missouri website. For technical questions about cleanup methods and decisions, contact the Remedial Project Manager.
