Explanation of Significant Differences, Ace Services Superfund Site, Colby, Thomas County, Kansas
The U.S. Environmental Protection Agency Region 7 (EPA), in cooperation with the Kansas Department of Health and Environment, is announcing the availability of the Explanation of Significant Differences (ESD) document for the Ace Services Superfund Site in Colby, Thomas County, Kansas. Under the Superfund law, EPA issues an ESD for a site cleanup change which differs from the original decision document but does not alter the overall remedy.
The site is located at 500 East Fourth Street in Colby, Kansas. Ace Services operated a chrome plating facility on a 2½-acre site from 1954 to 1990. The process they used to apply chrome plating to farm implement parts generated contaminated wastewater. The wastewater went to an unnamed tributary to Prairie Dog Creek.
The facility installed concrete retention vats and an evaporation lagoon to collect the wastewater. The evaporation lagoon was not lined, and chromium-contaminated wastewater seeped into the ground, contaminating the ground water.
Chromium-contaminated solid and sludge from the lagoon were removed from the site in 1981. Liquifed and solid wastes stored inside the Ace Services facility were removed in 1992. The facility buildings on the site were demolished in 2002. A city water line was extended to serve residences with affected residential water wells. Monitoring wells and residential wells were sampled to determine the extent of ground water contamination. To address contamination on the site, extraction wells were installed and a building housing an ion-exchange treatment process to clean the ground water was constructed. The water treatment system was finished in 2003 and the system and ground water are monitored regularly.
The cleanup change follows an EPA optimization study of the remedy which looked specifically at the former lagoon where soil contamination still exists at a depth which conventional methods cannot reach. Conclusions following the optimization study included the construction of a subsurface geo-membrane to inhibit the drainage of storm water into this area and to stop the further migration of contaminated ground water.
The ESD document and site Administrative Record are available at the following locations during normal business hours:
EPA Records Center
901 N. Fifth St.
Kansas City, Kansas
Pioneer Memorial Library
375 West 4th Street
Questions or requests for information can be submitted to:
Community Involvement Coordinator
EPA Region 7
901 N. Fifth St.
Kansas City, KS 66101
Toll-free: (800) 223-0425