EPA has signed a final decision document to address contamination near the “L Range” at the Massachusetts Military Reservation (MMR) on Cape Cod.
The decision addresses both the groundwater contamination and its source. The majority of the L Range groundwater contamination is located on the eastern portion of the base, abutting the Town of Sandwich boundary, and sampling and monitoring efforts have shown that it does not threaten public or private drinking water supplies.
Monitored natural attenuation, or natural reduction in the environment, with land-use controls will serve as the remedy for groundwater contaminated from former military training activities at the L Range. Land-use controls will ensure there is no future use of the contaminated water as long as groundwater contamination levels remain over the state action level.
Most of the surface source area contamination at the L Range has been removed, however, long term monitoring of the groundwater will take place to ensure the cleanup plan for the source is adequate. Long term groundwater monitoring will also help determine if the groundwater contamination levels are decreasing as modeled.
Groundwater modeling and sampling indicate that perchlorate concentrations in the L Range groundwater plume are already below the most conservative risk-based level. Under this plan, the most conservative risk-based level for RDX will be achieved by 2027. The chosen remedy will comply with state and federal standards that require that these remedies be protective of human health and the environment.
Earlier this year EPA sought public input on the possible cleanup alternatives for the L Range, on EPA’s proposed remedy of natural attenuation and land use controls, and on the rationale for EPA’s recommendation of this alternative. A public informational meeting was held on May 19, at the Forestdale School, in Sandwich, Mass. Submitted comments were considered by EPA, in consultation with the Massachusetts Department of Environmental Protection (MassDEP).