The Delaware Sand & Gravel Landfill sits on 27 acres in New Castle, Delaware. It accepted municipal and industrial wastes, including drums of chemicals, from 1968 to 1976. Leachate from those wastes contaminated soil and groundwater with hazardous chemicals. The EPA placed the site on the Superfund National Priorities List (NPL) in September 1983.
Soil at the site contains benzene, trichloroethene, polychlorinated biphenyls (PCBs), methylene chloride, and heavy metals including arsenic, lead, and antimony. Groundwater carries many of the same contaminants plus 1,4-dioxane, bis(2-chloroethyl)ether, 1,2-dichloroethane, phenol, and additional solvents. The main health risks come from ingesting or contacting these substances in soil or groundwater. The Artesian Water Company has treated water from the nearby Llangollen Well Field since 2000 to remove site-related contaminants, adding ultraviolet and hydrogen peroxide treatment for 1,4-dioxane in 2014 and additional filtration for manganese in 2019.
Cleanup has unfolded across six operable units (OUs), which are distinct areas each targeted for specific remedial work. Completed actions include excavating and removing contaminated drums and soil, installing an underground slurry wall around the Drum Disposal Area, operating a bio-venting system from 1997 to 2009, capping two waste areas, and extracting and treating contaminated groundwater. A special cap over 5 acres allows the landfill area to be reused for heavy equipment storage and similar purposes. Indoor air at an adjacent office building showed volatile organic compounds (VOCs) above acceptable levels in 2013, so a sub-slab depressurization system was installed in November 2014 and brought VOC levels into acceptable ranges. A landfill gas mitigation system added in 2017 prevents gas from migrating to neighboring properties.
The most recently added operable unit (OU06) addresses a source area and groundwater contamination. Remedial action on that unit began in May 2022, and construction of a shared groundwater remedy with the adjacent Army Creek Landfill Superfund Site is nearing completion as of 2025. The EPA's most recent five-year review, completed in August 2025, found the remedy protective of human health and the environment in the short term, with recommendations to ensure long-term protectiveness. Institutional controls remain in place, restricting land uses and prohibiting installation of new drinking water wells. The site has not yet been deleted from the NPL.
Community members can follow cleanup progress through factsheets published in September 2019, August 2022, June 2023, and September 2025, as well as through the site's Community Involvement Plan. The site's Administrative Record is available online or by appointment at the Delaware Department of Natural Resources and Environmental Control in New Castle or at the EPA Region 3 office in Philadelphia. The EPA's Community Involvement Coordinator and Remedial Project Manager are available to answer questions directly.
