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Sand, Gravel, and Stone
EPA Region 3 (Mid-Atlantic)
EPA ID# MDD980705164
1st Congressional District
Last Update: December 2012
Current Site StatusThe collection and treatment of contaminated groundwater at the site is continuing. The U.S. Environmental Protection Agency (EPA) announced its final cleanup decision for contaminated soils and shallow groundwater in its October 2002 Record of Decision (ROD) for this site. That plan is being implemented by parties that disposed of hazardous materials at the site (potentially responsible parties or PRPs) in accordance with a consent decree which became effective in June 2005.
Site DescriptionThe Sand, Gravel and Stone Site in Elkton, Maryland is a former sand and gravel quarry. From the late 1960s to the mid-1970s, the site was used for industrial waste disposal. The site accepted distillation wastes from a local solvent recycler. The dumping prompted citizen complaints due to odors, which eventually lead to a site investigation by State officials and the end of disposal activities. Early studies showed that shallow groundwater was heavily contaminated with a variety of organic chemicals. The contaminants include benzene, chlorobenzene and vinyl chloride. All local residents rely on groundwater as a drinking water source. Two hundred thousand gallons of liquid waste were removed from the site in 1974. These wastes were disposed of at the Kin Buc Landfill in Edison, New Jersey. Drums and sludge that remained after this work in 1974 were buried on-site in excavated pits.
- Site Responsibility
- Cleanup of this site is the responsibility of the federal government and parties potentially responsible for the site contamination.
- NPL Listing History
- Our country's most serious uncontrolled or abandoned hazardous waste sites can be cleaned using federal money. To be eligible for federal cleanup money, a site must be put on the National Priorities List (NPL). This site was proposed for listing on December 30, 1982. The site was added to the NPL on September 8, 1983.
Threats and Contaminants
Groundwater and soil are contaminated with several volatile organic compounds (VOCs), including benzene, chlorobenzene, 1,4-dioxane, 1,1,1-trichloroethane and vinyl chloride.
The VOCs have migrated from the shallow on-site groundwater into the groundwater of the underlying aquifer which is a source of water for local residents. Untreated site soil with low-level contamination presents a continuing source of ground water contamination. Site access is restricted by a fence around the perimeter of the facility.
Contaminant descriptions and risk factors are available from the Agency for Toxic Substances and Disease Registry, an arm of the CDC.
EPA's decisions on how to address site contamination are formally outlined in legal documents known as Records of Decision (RODs). EPA signed its first ROD for this site in 1985. The selected remedy included fencing the site, excavating buried drums and taking them off-site for disposal, and installing an interim pump-and-treat system for the shallow groundwater. In 1988, a group of 40 PRPs signed a consent decree with EPA, agreeing to do this work. The fencing was completed in 1989, and the excavation and removal of approximately 1,200 drums was completed in 1992.
The groundwater collection and treatment system has been operating for seventeen years. More than 200 million gallons of water have been treated to date.
In 1990, EPA signed a second ROD which addressed deeper groundwater. This ROD called for on-site and off-site groundwater monitoring, with provisions for alternate water supplies if residential wells were found to be contaminated, and additional pumping if deeper on-site wells were found to be contaminated. Two new parties joined the group of cooperating PRPs and in 1992, the 42 parties signed an amendment to the 1998 consent decree, agreeing to do this additional work.
During the first few years of monitoring, one residential well was found to contain site-related contaminants; this well has been replaced with a deeper well. Contamination has also been found in wells that monitor the aquifer directly below the contaminated shallow groundwater bearing zone. Contaminated groundwater is being pumped from this aquifer and treated on-site. The extent of the contamination has been delineated and plans for installing additional groundwater collection systems were approved by EPA in November 2010. These systems are being installed as access agreements with the owners of affected properties are finalized.
EPA signed the third and final ROD for this site in 2002. The final cleanup plan includes: excavating contaminated soil; treating this soil on-site using low-temperature thermal desorption; backfilling of treated soil; expanding the recovery and treatment system for shallow groundwater and continuing its operation; and adding safe substances (e.g., oxygen or molasses) to the soil and groundwater in order to facilitate the breakdown of hazardous substances by soil microbes.
A group of 40 PRPs signed a new consent decree with EPA, agreeing to implement the final cleanup plan for the site. The consent decree became effective in June 2005. The PRPs have since installed an additional shallow groundwater collection trench which began operating in 2008. De-watering of site soil also began in 2008 in preparation for soil excavation work and bioventing (blowing air through soil in order to stimulate the breakdown of biodegradable contaminants by microbes in the soil). In 2010, the most highly contaminated soil was excavated and treated on-site using thermal desorption. 57,500 tons of contaminated soil were treated and backfilled on-site. An additional 7,770 tons of contaminated soil and waste were shipped off-site to approved hazardous waste disposal facilities. Afterward, the site was graded and reseeded. A bioventing system was installed at the site in 2011 in order to stimulate biodegradation of the remaining low-level contamination and system performance is regularly monitored.