Plans to Restart City of St. Charles Drinking Water Wells

In November 2022, the City submitted a notice to the USEPA and Missouri DNR requesting the development of a comprehensive plan for the safe restart of drinking water wells CW-4, CW-5, CW-6, and CW-8 before the end of the year. It should be noted this was prior to the identification of contamination in City drinking water well CW-9. Specifically, the City requested the Agencies develop a plan to remove the hazardous chemicals present in groundwater from Ameren Missouri and others as part of restarting the four drinking water wells and to ensure the safety of the citizens of the City of St. Charles. In separate responses submitted to the City in early December 2022, the USEPA and Missouri DNR proposed that following the restart of any of the shutdown drinking water wells in the Elm Point Wellfield, additional monitoring would be conducted within the drinking water well, in addition to the Elm Point water treatment plant by Ameren Missouri, the other responsible parties, and the Missouri DNR. Both the USEPA and Missouri DNR indicated that the four drinking water wells could be safely restarted despite the presence of hazardous chemicals, as long as the contaminated water is mixed or blended with water from wells that do not have contamination. There are only two City drinking water wells that are currently free of contamination from Ameren Missouri and the other responsible parties.

The Missouri DNR also stated that it is the responsibility of the City, not Ameren Missouri or the other polluters, to ensure that safe drinking water is delivered to the City’s citizens and the City would be placed on a compliance monitoring plan if contaminants were detected in the effluent leaving the Elm Point water treatment plant. The USEPA and Missouri DNR have both stated that an exceedance of an MCL for a contaminant within the treated water that is being consumed by the City’s citizens is based on “a running annual average of four quarters of data.” This would imply that the City’s citizens would be allowed to consume water at unsafe levels for four quarters before any further action is taken by the Missouri DNR or the USEPA.

The City has found these recommendations to be woefully inadequate, the enforcement actions proposed by Missouri DNR to be levied against the City for operating the drinking water wells that have been contaminated by Ameren and others to be unacceptable, and the proposal for the citizens of the City to drink contaminated water for up to a year to be preposterous. Instead, the companies that released contaminants into the Elm Point Wellfield should be held responsible for ensuring the design, installation, testing, operation, maintenance, and monitoring of a treatment system specifically designed to remove their contamination. This will ensure the continuous safety of the drinking water for the citizens of St. Charles.

Subsequently, the USEPA has requested that the City of St. Charles delay the restart of City drinking water wells CW-4, CW-5, and CW-6 until the limited subsurface investigation and additional pilot testing of in-situ treatment on the Ameren Huster Road Substation is completed. This would mean that the City of St. Charles would have to continue to purchase water from the City of St. Louis until Ameren Missouri and the USEPA complete this remediation and investigation activities sometime between February and March 2023.

The City is not satisfied with the USEPA and Missouri DNR proposed plan for restarting wells that have previously or currently contain hazardous chemicals from Ameren Missouri or others. The City is in the process of pilot testing an additional treatment technology beginning in early February to measure effectiveness of removing contaminants from groundwater following the restart of the City’s drinking water wells. The City is also developing a plan for additional monitoring that would be performed prior to and following the restart of a drinking water well. This would include testing to evaluate the presence of contamination prior to restarting the drinking water well, followed by weekly sampling in the drinking water well and nearby sentinel wells. These sentinel wells would be used to predict the migration of hazardous chemicals prior to migrating into a drinking water well once restarted. The City would also continue with weekly monitoring of the influent and effluent in the Elm Point Treatment Plant. The USEPA and Missouri DNR would require the responsible parties to conduct some of this monitoring in the drinking water wells at the restart of each well. A limited number of samples would be collected by the Missouri DNR in the treatment plant. The City would be responsible for collecting any samples in the sentinel wells, drinking water wells, or treatment plant that is beyond the scope and schedule agreed to by the responsible parties with the USEPA. The City of St. Charles was never asked to provide their recommendations for an appropriate scope or schedule for monitoring following the restart of the drinking water wells.