Rocky Hill Municipal Well

Overview

Rocky Hill Municipal Well is a Superfund site in Rocky Hill Borough, Somerset County, New Jersey. It supplied drinking water to local residents until contamination forced both municipal wells to close, the first in 1978 and the second in 1979. The U.S. Environmental Protection Agency (EPA) added the site to the National Priorities List (NPL) in September 1983. The NPL is the federal list of the most contaminated sites in the country that qualify for long-term cleanup funding.

Eleven contaminants of concern have been identified, all found in groundwater. They are 1,1-dichloroethene, arsenic, barium, beryllium, chlordane, chromium, lead, nickel, silver, tetrachloroethene, and trichloroethene (TCE). TCE was the main driver of the original well closures, with concentrations measured between roughly 50 and 200 micrograms per liter from 1978 to 1983. All of these substances are addressed through the groundwater remedy, designated as Operable Unit 02.

EPA selected a cleanup remedy in 1988. It called for extracting and treating contaminated groundwater using carbon adsorption and air stripping, connecting affected residences to public water supply as needed, sealing private wells within the contaminated plume, and ongoing monitoring. Pump-and-treat systems were completed in 2004 and 2005. A 2005 modification to the remedy added surface water discharge as a treatment option. The New Jersey Department of Environmental Protection (NJDEP) established a Groundwater Classification Exception Area and a remedial action covenant in June 2014 to formalize land-use restrictions. Zoning controls limit uses that would be inconsistent with current cleanup levels. Operation and maintenance of the groundwater remedy transferred from EPA to state control in September 2024.

The site has reached several key milestones. Physical construction of the cleanup is complete across the entire site. Human exposure is under control, and contaminated groundwater movement is stabilized with no unacceptable discharge to surface water. The site achieved sitewide ready for anticipated reuse status in July 2017, meaning cleanup goals have been met for current and reasonably anticipated future land uses. Five-year reviews in 2010, 2016, and 2020 confirmed the remedy continues to protect human health and the environment. The most recent five-year review was completed in May 2025. The site has not yet been deleted from the NPL.

Community members can review site documents in person at three locations: the EPA Superfund Records Center at 290 Broadway, 18th floor in New York City; the Mary Jacobs Memorial Branch Library at 62 Washington Street in Rocky Hill, New Jersey; and the Montgomery Township Municipal Building at 2261 Route 206 in Belle Mead, New Jersey. For direct questions, contact the EPA Community Involvement Coordinator or Remedial Project Manager assigned to the site.