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(Lenexa, Kan., Feb. 4, 2021) - The U.S. Environmental Protection Agency (EPA) has announced the proposal of a preferred alternative for the cleanup at the Findett/Huster Road Substation Superfund Site (site), Operable Unit-4 (OU-4) in St. Charles, Missouri.

The remedy identified in the Proposed Plan as Alternative 3 includes on-site treatment of soil, extraction and treatment of contaminated groundwater, and institutional controls. OU-4 consists of contaminated soil and groundwater at the Ameren Missouri Huster Road Substation (substation).

EPA will host a virtual Public Meeting on Tuesday, Feb. 9, from 6 to 7:30 p.m. to provide an overview of the selected remedy, answer questions, and provide an opportunity for residents to participate in the public comment period. To join the virtual meeting, please visit the Site Profile Page.

In June 2010, volatile organic compounds (VOCs) were detected in City Well 5 of the Elm Point Wellfield, located approximately 180 feet north of the substation boundary. Ameren Missouri had previously used a chlorinated solvent containing VOCs for degreasing and metal cleaning at the substation. From 2012 through 2020, Ameren Missouri conducted a number of investigations and pilot studies that evaluated several soil and groundwater treatment options and installed a groundwater extraction and treatment system along the northern border of the substation property.

OU-4 is the last of the site’s four operable units to be addressed through the remedial process. The proposed cleanup action at OU-4 will prevent current and future exposure to contaminated groundwater. Restrictions on groundwater usage and a combination of treatment and monitoring of contaminated groundwater will prevent potential human exposure.

EPA is proposing that Alternative 3 be selected for OU-4’s cleanup because it has already shown to be a viable technology to remove chlorinated solvents from groundwater. Alternative 3 will also continue to achieve substantial risk reduction by both treating the source area and providing safe management of remaining material. Based upon results obtained thus far from various pilot studies and confirmed by the most recent sampling event (December 2019), the contaminants at the site have responded to treatment applications and continue to degrade. Compliance with federal drinking water regulations for the contaminants is achievable within an acceptable time frame.

The Proposed Plan is subject to a public comment period that started Feb. 2 and runs through March 1, 2021. The Proposed Plan and information on how to submit comments during the comment period are available on the Site Profile Page.

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