USEPA Limited Subsurface Investigation

In March 2022, following the detections of hazardous chemicals in City drinking water well CW-6, Ameren Missouri and the USEPA indicated that a work plan for an investigation to assess the extent of contaminant migration from beneath the Ameren Huster Road Substation would be prepared and submitted to the City of St. Charles for review. This work plan was promised by Ameren Missouri and the USEPA multiple times over the next several months. Then in October 2022, the USEPA informed the City of St. Charles that Ameren Missouri would not be conducting a limited subsurface investigation. Instead, the USEPA identified that they would take the lead conducting the limited subsurface investigation. USEPA claimed the City refused to allow access to Ameren Missouri on City property near drinking water well CW-6. At no time has the City refused access to Ameren Missouri and simply required Ameren Missouri to provide the work plan that had been promised since March 2022 prior to beginning of any work.

The USEPA provided the City of St. Charles the work plan for the limited subsurface investigation on November 16, 2022. On November 29, 2022, prior to the City completing the review of the work plan, the USEPA notified 212 Environmental Consulting, LLC of their intent to begin the limited investigation near drinking water well CW-6 on December 5, 2022. The USEPA decided to start the investigation prior to receiving comments regarding the work plan from the City or meeting with the City to discuss their concerns, as was originally promised by the USEPA. This notification was provided by the USEPA just five days prior to the beginning of what the USEPA called the “long-planned start of work.”

The City completed a review of the work plan and provided comments to the USEPA, as well as an access agreement to perform the investigation activities on City-owned property on December 2, 2022. The City also requested that the USEPA also provide proof of insurance from the contractors that were hired to perform the investigation on behalf of the USEPA. It is a requirement that any contractor performing work on City-owned property complete an access agreement and provide proof of adequate insurance to protect the City of St. Charles from any possible damages that may occur because of the contractors’ actions, purposeful or otherwise.

On December 5, 2022, the USEPA informed the City of St. Charles that the limited subsurface investigation would be delayed as the contractor for the USEPA would need time to review the access agreement and provide the proof of insurance to perform work on City-owned property. The USEPA stated that the reason for the delay was due to access to the property being denied by the City of St. Charles. It should be noted that the City of St. Charles did not deny access to City-owned property to conduct the limited subsurface investigation. The City simply asked that the USEPA and their contractors comply with the requirements of any other business performing work on City owned property.

Between late December 2022 and early January 2023, the USEPA provided the City of St. Charles with an access agreement and proof of insurance for their contractors in accordance with the City’s requirements. The limited subsurface investigation is scheduled to be conducted by the USEPA between January 16 and February 3, 2023. This investigation will include the collection six soil samples at three locations and as many as 50 groundwater samples from 16 locations. The majority of the investigation activities will be performed near City drinking water well CW-6. The soil and groundwater samples will be collected using a one-time, direct-push sampling technique. The City of St. Charles strongly objects to the use of direct-push technology as a part of this investigation near City well CW-6. According to the USEPA’s own report, direct-push groundwater sampling can create strong bias in contaminant concentrations caused by sample disturbance (i.e., pressure decreases, temperature increases, etc.), the sampling interval (may not represent the zones of contamination), and sample cross-contamination (i.e., contaminant drag-down, creating hydraulic conduits, improper decontamination). Ameren Missouri has historically opposed the use of direct push investigative approaches in the Elm Point Wellfield to assess the possibility of alternate sources of contamination. Furthermore, the USEPA has not stated how the data collected as part of this investigation will be used to show that the City sanitary sewer or some other source is causing the contamination near well CW-6. In fact, the USEPA has indicated that more phases of work may be necessary to determine if there is another source of contamination near City well CW-6, which could take many more months or years to complete. Lastly, the USEPA has also not provided any explanation or work plan for investigating the contamination that has been discovered in City drinking water wells CW-8 and CW-9.

In response to concerns regarding the limited scope of the investigation being performed by the USEPA and the uncertainty in how the data will be used, the City of St. Charles has elected to conduct its own independent investigation. The City’s investigation will include the installation of 26 permanent monitoring wells at 13 locations. Groundwater samples can be repeatedly sampled from these new wells to better define the extent of contamination emanating from the Ameren Huster Road Substation and provide an early warning of migration of hazardous chemicals towards the City’s drinking water wells. The City’s independent investigation will begin in late January 2023.