ST. CHARLES, Mo. – One week after the Environmental Protection Agency confirmed an Ameren Missouri substation as the source of contamination at St. Charles’ Elm Point Wellfield, city leaders announced Thursday that it had shut down the sixth of its seven water wells due to contamination concerns.

The city’s public works department closed City Well #7 after detecting contaminants. However, the city insists that its drinking water remains safe to consume.

Last October, St. Charles Mayor Dan Borgmeyer said the majority of the city’s water wells had been shut down due to contamination of hazardous chemicals. By December, the city had down five of its seven wells.

The St. Charles Wellhead District is the primary source of drinking water for the city. At one point, the district was able to produce six million gallons of water per day for St. Charles. As of December 2022, production was reduced to 1.5 million gallons. Officials have not said how much water the city can produce with just one active well.

Borgmeyer pointed the finger at Ameren’s Huster Road Substation, located near the Elm Point Wellfield, and said it was leaking carcinogens into the soil and groundwater.

In the 1970s, Ameren Missouri used a scouring solvent called tetrachloroethylene to clean equipment at the substation, according to Paul Michalski, a senior hydrogeologist for 212 Environmental. Ameren attempted to degrade the chemical in soil and groundwater. Two carcinogens were created in the process—cis-1,2-Dichloroethene and vinyl chloride—both of which are harmful to human beings.

Ameren claimed at the time, “cleanup of the Huster substation has been successful in reducing on-site, and off-site impact from a cleaning produce last used decades ago.” 

In January 2023, the EPA collected both ground and water samples from the Elm Point Wellfield. Lab results confirmed the presence of both of cis-1,2-Dichloroethene and vinyl chloride and identified the Ameren substation as the source.

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When the EPA’s report was released last week, an Ameren Missouri spokesman said its work is being monitored by the EPA, and they expect to see a reduction in the concentration of these hazardous chemicals by early summer.

The EPA will present additional information on its sampling and testing results at an upcoming meeting on Feb. 23 at 6 p.m. at the St. Charles Borromeo Catholic Parish gymnasium.

According to the EPA, the “polluter pays principle” applies, meaning Ameren has to shoulder the financial burden for cleaning up the mess. Borgmeyer has demanded that Ameren cover the $40 million cost of moving the water wells.