Keystone Sanitation Landfill

Overview

Keystone Sanitation Landfill is a 40-acre inactive landfill in Union Township, Adams County, Pennsylvania. It operated from 1966 through 1990, accepting municipal, industrial, and construction wastes without a liner or leachate containment system. The site was added to the Superfund National Priorities List in 1987 after volatile organic compounds turned up in on-site and nearby residential wells as early as 1982.

Contaminants of concern include volatile organic compounds such as trichloroethene, tetrachloroethene, vinyl chloride, and benzene. Heavy metals including arsenic, chromium, lead, mercury, cadmium, beryllium, and nickel are also present. Pesticides such as aldrin, dieldrin, heptachlor, and heptachlor epoxide have been detected, along with phthalates and other semi-volatile compounds. Most contamination sits in groundwater, though arsenic, beryllium, chromium, and mercury are also found in soil. Mercury was found in sediment, and arsenic was detected in surface water. The emerging contaminant 1,4-dioxane has also been identified in leachate and groundwater.

EPA selected a cleanup remedy in 1990 and modified it in 1999 and 2000. Work is organized into four operable units covering the fenced landfill area, an offsite investigation area, a cap and gas system, and a groundwater pump-and-treat system. All major remedy components were in place by 2004. Two groups of potentially responsible parties manage the work under EPA oversight: Waste Management and related companies handle the landfill, and eight original generator defendants oversee the groundwater remedy. Cleanup actions include groundwater extraction and treatment, point-of-entry treatment on residential wells, landfill gas extraction, and a landfill soil cover. A combined remedial investigation and feasibility study for the cap and gas operable unit began in June 2022 and is estimated to finish between March and May 2027. EPA plans to issue a Proposed Remedial Action Plan in 2026 for public review and comment.

The site achieved the EPA's Sitewide Ready for Anticipated Use designation in September 2016. Human exposure is under control, groundwater migration is stabilized, and the capped landfill area is grass-covered. EPA's most recent Five-Year Review, completed in September 2025, continues to assess protectiveness. Outstanding issues being addressed include 1,4-dioxane in leachate and groundwater, ponding and subsidence in the landfill cover, and high manganese concentrations in some wells. Institutional controls restrict construction and land use on site, and a 500-foot buffer zone requires anyone planning to install a new well to contact the EPA Remedial Project Manager first.

Community members can engage through EPA's Community Involvement Program. Public notices have been issued, and EPA plans to release a Proposed Remedial Action Plan in 2026 for public review and comment. Records are available online and at the Hanover Public Library in Hanover, Pennsylvania, or at the EPA Region 3 office in Philadelphia. Visitors should call ahead to schedule an appointment.