The Keystone Sanitation Landfill is located in Adams County, Pennsylvania. It occupies an area of approximately 40 acres in a gently rolling, predominantly agricultural setting. The landfill was used from 1966 until 1990 for disposal of household and municipal waste and certain types of industrial and construction debris.
The landfill is situated on a ridge, and surface-water runoff flows from the site in all directions. Conewago Creek, a tributary to the Susquehanna River, drains the northern and eastern portions of the site. Piney Creek, a tributary to the Monocacy and Potomac Rivers, drains the southern and western portions of the site.
Chemical analysis of environmental media on and near the site began in 1974 following installation of monitoring wells around the perimeter of the property. A Remedial Investigation (RI) was conducted by the Environmental Protection Agency (EPA) during 1989 and 1990. Results of well monitoring and the RI work revealed that the groundwater under and near the site, the surface soil on and near the site, and the surface water and sediment in some of the small streams near the site were contaminated with volatile organic compounds, and heavy metals including mercury, zinc, and manganese.