ADEQ: Contamination at Chino Valley Circle K confined to soil above aquitard; groundwater not impacted, remediation continues

Chris Marks, a manager with the Arizona Department of Environmental Quality's corrective action unit, told the Chino Valley Town Council that ADEQ has approved the site characterization for the fuel release at the Circle K on Jan. 3, 2024, but that remediation and monitoring must continue.

ADEQ said the investigation found contamination confined to soil above a clay-rich aquitard about 150 feet below ground and that regional groundwater and nearby private drinking wells have not been impacted. "There is no current threat to a drinking water resource by any members of the community from this release," Marks said.

The site investigation included 18 soil borings (several converted to monitoring wells), four monitoring wells screened in the regional aquifer, sampling of seven nearby private wells, and two soil-gas surveys. ADEQ said Circle K has installed remedial wells and is operating a soil vapor extraction (SVE) system that draws vapors to a treatment compound where an oxidizer treats extracted vapors.

ADEQ reported the SVE system has removed an estimated 118,000 pounds of hydrocarbons (a rough estimate equivalent to about…