Hazardous chemicals are present in soil and groundwater beneath the Ameren Missouri Huster Road Substation, as well as to the north beneath Missouri State Route 370 and to the south towards the City of St. Charles drinking water well CW-8. The contamination present from the Ameren Missouri Huster Road substation is referred to as Operable Unit No. 4 by the USEPA and Missouri DNR. The extent of the contamination has not been fully defined by Ameren Missouri, USEPA, or Missouri DNR. Hazardous chemicals present in groundwater from the substation include:
• Vinyl chloride
In 2012, the USEPA and Ameren Missouri entered into a Settlement Agreement that required Ameren to:
• Perform soil and groundwater monitoring to determine the extent of contamination
• Contain and treat contaminated groundwater from moving beyond the substation property
• Evaluate options for removing hazardous chemicals from soil and groundwater
A small groundwater treatment system was installed by Ameren Missouri in the northern portion of the substation to try to reduce the movement of chemicals to the north towards the City of St. Charles drinking water wells CW-6, CW-7, and CW-9. However, nothing was done to prevent the chemicals in groundwater from moving towards the other City drinking water wells CW-8 and CW-10. Between 2014 and 2018, Ameren Missouri tested multiple technologies to remove hazardous chemicals present in soil and groundwater beneath the substation.
It is important to know that in 2019 as part of evaluating potential risks to human health, Ameren Missouri, USEPA, and Missouri DNR concluded that a person drinking water from beneath the substation would experience a 1 in 5 chance of developing cancer in their lifetime. For reference, USEPA guidelines provide that safe levels only allow for 1 person per 1,000,000 to develop cancer. In addition, this risk evaluation concluded that a person drinking water from beneath the Ameren Missouri substation would experience a 950 times higher risk of developing other non-cancer related diseases compared to the levels considered safe according to guidelines developed by the USEPA.
City drinking water well CW-4 is located right next to the Ameren Huster Road substation and well CW-5 was installed immediately north of the substation. These two drinking water wells were shut down by the City of St. Charles voluntarily many years ago due to concerns with the contamination in the Elm Point Wellfield. Additionally, the City has repeatedly requested that USEPA, Missouri DNR, and Ameren replace drinking water wells CW-4 and CW-5 as well as provide upgrades to the City water treatment plant to remove these hazardous chemicals from the groundwater.