Agency Will Cap Standard Chlorine Site and Treat Soil Gas

The U.S. Environmental Protection Agency has selected a cleanup plan to address contaminated soil at the Standard Chlorine of Delaware Superfund site in New Castle County, Del., that includes constructing a surface cap over a contaminated area and a soil gas collection and treatment system.

The Standard Chlorine of Delaware, Inc. Superfund Site (also known as Metachem) is three miles northwest of Delaware City. It is approximately 65 acres in size, and is west of River Road (Route 9) near the south bank of Red Lion Creek.

Metachem, which had been conducting site cleanup since 1987, declared bankruptcy in 2002. This led to EPA becoming the lead agency for the cleanup. After conducting extensive groundwater and soil sampling, EPA considered various cleanup options to address the soil contamination. In July 2009, EPA recommended a cleanup plan that included a surface cap and soil gas treatment system. The plan was made available for public comment, and after reviewing comments, EPA decided to implement the recommended plan.

The remedy includes a cap designed to prevent contact or migration of contaminated soils or soil gas. The 23-acre surface cap will be connected to the already constructed underground groundwater containment barrier. The soil gas collection and treatment system will consist of 200-500 air extraction wells that will be connected to a carbon absorption treatment system. The plan also calls for legal protections which will both protect the cap and allow for controlled reuse of the property in the future.

EPA’s record of decision document can be reviewed at and at these three locations:

  • Delaware City Public Library, 250 Fifth Street, Delaware City, Del.
  • Delaware Dept. of Natural Resources and Environmental Control, 391 Lukens Dr., New Castle, Del.
  • U.S. EPA Region 3 Office, 1650 Arch Street, Philadelphia, Pa.