The U.S. Environmental Protection Agency directed Ameren to submit a draft Focused Feasibility Study to the Agency by June 30, 2023. EPA required Ameren to conduct additional work in February, after field work conducted by EPA in January identified Ameren’s Huster Road Substation as a source of the new contamination in the Elm Point Wellfield in St. Charles, Missouri.
“EPA continues to hold Ameren accountable for the groundwater contamination emanating from the Huster Road Substation,” said EPA Region 7 Superfund and Emergency Management Division Director Bob Jurgens. “The Focused Feasibility Study will take into account the additionally identified contamination and evaluate various remedial technologies for groundwater cleanup. EPA will oversee all of Ameren’s work to ensure that it meets Superfund’s requirements.”
The FFS process consists of the development and detailed analysis of cleanup options to establish the basis for remedy selection decisions that will be made by the EPA. The FFS will present a range of viable cleanup options that meet the site’s cleanup goals. The cleanup goals set forth in the 2021 Record of Decision (ROD) include preventing exposure to contaminants of concern (COCs) above the Safe Drinking Water Act’s maximum contaminant levels (MCLs) in groundwater; preventing potential future risks to humans from inhalation of groundwater COCs via the vapor intrusion pathway; preventing future migration of groundwater contamination off-site; and restoring groundwater to beneficial use (i.e., at or below MCLs) within a reasonable time frame.
As part of the FFS process, EPA may require Ameren to submit work plans to the Agency to define the extent of the contaminant plume. Additionally, EPA expects Ameren to use ongoing interim response actions to address the contamination. These approved response actions include the use of a permeable barrier that breaks down contaminants as they pass through it, and chemical oxidant and/or bacteria enhancement injections into the groundwater to break down the contaminants.
EPA will continue to review all future documents or plans submitted and require Ameren to correct any deficiencies before granting approval to begin future work.
The letter directing Ameren to complete the draft FFS by June 30 is available on EPA’s Site Profile page. Ameren must supply a written confirmation to EPA by March 24, 2023, that it agrees to perform the work described in the letter.
