Coker's Sanitation Service Landfills

Overview

Two landfills in Cheswold, Kent County, Delaware accepted latex waste sludge from 1969 to 1980. That waste contaminated soil, groundwater, leachate, and solid waste at the site. The Columbia Aquifer sits directly beneath the site and was affected. The Cheswold Aquifer, used for drinking water in the area, was also a concern. EPA added the site to the Superfund National Priorities List in July 1987 and deleted it in August 2011 after cleanup goals were met.

The main contaminants include volatile organic compounds such as benzene, toluene, trichloroethene, styrene, chloroform, and ethylbenzene. Heavy metals and metalloids found at the site include aluminum, antimony, barium, beryllium, cadmium, and manganese. Other organic compounds detected include xylene, phenol, cresol, carbon disulfide, dibutyl phthalate, and 1,2,3-trichloropropane. Recent groundwater monitoring beneath both landfills did not detect these compounds. The site does not pose a risk to residents using groundwater for drinking water, and nearby surface water and wetlands have not been adversely impacted.

A Consent Decree signed in April 1992 required six potentially responsible parties and the Delaware Department of Natural Resources and Environmental Control to build the cleanup remedy. That remedy included covering the landfills, installing a perimeter fence with warning signs, sealing leachate collection wells, leveling one landfill to improve drainage, and setting up a groundwater sampling program. Construction was completed in September 1993, with remedial action work continuing into 2001. Monitoring from the mid-1990s through 1998 confirmed the remedy was working.

Because hazardous substances remain in the landfills above safe levels, institutional controls restrict land use and prevent well construction near the site. Delaware established a groundwater management zone for that purpose. Zoning restrictions also prohibit residential and other incompatible uses. EPA conducts five-year reviews to confirm the remedy continues to protect public health and the environment. The most recent review was completed in May 2024 and confirmed the remedy remains protective. The next review is scheduled for 2029.

Community members with questions can contact the EPA's Community Involvement Coordinator. EPA also encourages residents to learn about ways to participate through its Community Involvement Program. Physical records are available at the Smyrna Public Library in Smyrna, Delaware, or at the U.S. EPA Region 3 office in Philadelphia, Pennsylvania, by scheduling an appointment at (215) 814-2396.