EPA Completes Sixth Five-Year Review for Findett Corp. Superfund Site in St. Charles, Missouri
Report examines protectiveness of remedies for Operable Units 1, 2, and 3
LENEXA, KAN. (JUNE 17, 2025) – The U.S. Environmental Protection Agency (EPA) has completed the Sixth Five-Year Review for the Findett Corp. Superfund Site in St. Charles, Missouri.
This review examined Operable Units (OUs) 1, 2, and 3. OU4, commonly referred to as the Ameren Huster Road Substation, was not included in this review, as construction of a remedy has not started yet.
Five-Year Reviews provide an opportunity to evaluate the implementation and performance of a remedy and to determine if that remedy remains protective of human health and the environment.
“EPA will continue to direct and oversee the work performed by Potentially Responsible Parties at the Findett Superfund Site,” said EPA Region 7 Superfund and Emergency Management Director Bob Jurgens. “We are committed to driving the work performed at the site to completion and continuing to engage with the community and our state and local partners.”
The Sixth Five-Year Review deferred protectiveness determinations for OUs 1 and 2 until further information is obtained. The remedy for OU3 was deemed short-term protective through monitored natural attenuation.
EPA noted several issues and recommendations that it intends to direct appropriate Potentially Responsible Parties to take across OUs 1, 2, and 3.
Operable Units 1 and 2
There is a potential ecological risk due to historic discharges, and no ecological risk assessment has been conducted to date.
EPA recommends that a screening-level ecological risk assessment (SLERA) be performed for soils and sediment in and around OUs 1 and 2 for land-based and aquatic habitats. EPA has conditionally approved a SLERA work plan to resolve this issue. Once the SLERA is completed, EPA will write an addendum to the Five-Year Review with a protectiveness determination.
Operable Units 1, 2, and 3
Continued contaminant migration from OUs 1 and 2 into OU3 impacts the remedial timeline for OU3.
EPA recommends completing the ongoing contingency process for OU3 and implementing additional remedial actions to prevent migration of contaminants. Additionally, EPA recommends completing the ongoing evaluation of the existing groundwater extraction and treatment system to determine its effectiveness and whether improvements are necessary.
Operable Unit 3
The estimated remedial timeline for OU3 is longer than the time frame established by the Record of Decision. To accelerate the remedial timeline, EPA recommends completing the ongoing contingency process and implementing additional remedial actions.
OU3 is experiencing routine exceedances of the maximum contaminant level for vinyl chloride at point-of-compliance wells. While these exceedances historically fluctuate and do not impact the finished drinking water, EPA recommends additional remedial actions to mitigate risk and restore the aquifer to unlimited use.
EPA will present findings from the Sixth Five-Year Review to the Findett Corp. Superfund Site’s Community Advisory Group on Aug. 14, 2025. More details will be shared closer to the event.
Read the Sixth Five-Year Review for the Findett Corp. Superfund Site.
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