Mansfield Trail Dump

Overview

From the 1950s through the early 1970s, disposal trenches in a wooded area near the Mansfield Bike Path in Byram Township, Sussex County, New Jersey received septic and industrial waste. Those trenches released trichloroethene (TCE) and other volatile organic compounds into groundwater, soil gas, and indoor air. TCE and related compounds, including cis-1,2-dichloroethene and vinyl chloride, migrated to 19 nearby residential drinking water wells. EPA added the site to the National Priorities List in March 2011 and split cleanup into separate operable units to handle different areas and problems.

EPA identified 16 contaminants of concern at the site. Groundwater across the site contains chlorinated solvents including TCE, 1,1,1-trichloroethane, 1,1-dichloroethane, 1,1-dichloroethene, cis-1,2-dichloroethene, vinyl chloride, chlorobenzene, and 1,4-dioxane. The waterline area also contains chromium, cobalt, and nickel. Lead and polychlorinated biphenyls (PCBs) appear in soil throughout the site.

Cleanup actions are well underway. In 2012, EPA excavated about 11,170 tons of non-hazardous waste and 383 tons of hazardous waste from the disposal trenches, then re-graded and restored the area. The New Jersey Department of Environmental Protection installed carbon water filtration systems in 19 homes and sub-slab depressurization systems in five homes to limit exposure from contaminated groundwater and indoor vapors. Those five vapor intrusion systems continue to operate and receive annual EPA inspections. EPA finalized its cleanup plan for the broader site in September 2019 and issued an Explanation of Significant Differences to that plan on September 30, 2025. Remedial design for the municipal waterline connection was completed in September 2023, with construction estimated to finish between September and November 2028. Human exposure is currently under control through the treatment systems in place, but groundwater migration is not yet under control and physical construction is not complete.

Current work includes designing treatment for deep groundwater contamination and conducting soil investigation studies along the Mansfield Bike Path. EPA completed a removal action in 2023 in addition to the earlier 2012 action. The agency also completed pre-design pilot studies in 2024 to test soil and treat groundwater near the bike path.

Community members can get involved through EPA's Community Involvement Program. EPA issued a Frequently Asked Questions document in October 2025 and provided a community update in September 2024. Site records are available for public review at the Sussex County Library Louise Childs Branch in Stanhope, New Jersey, and at the EPA Superfund Records Center in New York City. For questions, contact Community Involvement Coordinator Olivia Cappo or Remedial Project Manager Brent Gaylord.