ADEQ: Circle K contamination confined to soil; remediation underway, agency disputes 86,000-gallon estimate

Chris Marks of the Arizona Department of Environmental Quality told the Chino Valley Town Council on Nov. 5 that investigators have completed site characterization for the fuel release at the Circle K convenience store and that contamination is confined to soil above a clay aquitard, with no evidence of impact to the regional aquifer.

"We have crossed the site characterization phase," Marks said. "The extent of the release, at this point, the impacts are restricted to soil." He added, "Thus, there is no current threat to a drinking water resource by any members of the community from this release."

The department summarized the investigative work: 18 soil borings (some converted to monitoring wells), four regional-aquifer monitoring wells sited between the property and nearby private wells, sampling of seven private drinking-water wells, and two soil-gas surveys to check for vapor hazards. ADEQ said the lithology under the tank basin is interbedded sands, silts and clays and that a sharp increase in clay content near 150 feet forms an aquitard that limits downward migration.

Circle K reported a suspected release in early January 2024 after a technician observed fuel spraying into the containment sump for a submersible turbine pump. The company repaired the pump and sump in February and began remediation in…