Hidden Lane Landfill is a 25-acre privately operated dump that closed in 1986 after accepting construction debris, appliances, tires, and other solid waste since 1971. It sits next to the Potomac River floodplain in Sterling, Virginia. EPA added it to the National Priorities List (NPL) in March 2008 after the degreasing solvent trichloroethylene (TCE) turned up in drinking water wells in the nearby Broad Run Farms subdivision. The site is being cleaned up in multiple operable units (OUs), each targeting a different problem area.
Six contaminants of concern have been identified in groundwater and soil. They include TCE, cis-1,2-dichloroethene, 1,1-dichloroethene, and chloroethene (also called vinyl chloride). EPA also found PFAS, specifically perfluorohexanesulfonic acid, perfluorooctanoic acid, and perfluorooctanesulfonic acid, in both groundwater monitoring wells and residential wells at levels above Safe Drinking Water standards. The updated cleanup plan now covers these PFAS chemicals as well.
EPA has taken several cleanup steps. Carbon filtration systems were installed in Broad Run Farms starting in 2008, and quarterly sampling continues. Monitoring wells installed between 2009 and 2011 showed TCE moving northward toward the Potomac River. Indoor vapor testing at 18 nearby properties in 2015 found no vapors entering homes. In early November 2024, EPA finished excavating roughly 15,000 tons of contaminated soil and debris from the former landfill. The excavated area was backfilled with clean fill and topsoil. A bedrock pilot study is planned for 2025 to prepare for in-situ bioremediation and chemical reduction of TCE still in bedrock groundwater.
Construction of a public waterline began in mid-October 2025 and will eventually connect 117 households to the Loudoun Water utility. The line will run nearly four miles and is scheduled for completion by fall 2027, in seven phases over roughly two years. Until the waterline reaches each property, EPA is providing temporary alternate water supplies to residents whose wells exceed safe contamination levels. Overall, human exposure across the site is currently under control, meaning EPA has determined there are no unacceptable exposure pathways at this time. Groundwater migration status cannot yet be determined due to insufficient data on contamination extent and movement.
Residents can get involved by attending meetings EPA and the Army Corps of Engineers hold with property owners before construction begins in each area. People can also review site documents at the Cascades Library in Potomac Falls or by appointment at EPA Region 3 in Philadelphia. The site's Community Involvement Coordinator and Remedial Project Manager can answer questions directly.
