The Northwest Corner investigation area is located on the corner of Camp Edwards that runs along Canal View Road in Bourne. The site is an ~4,700 x ~3,750 ft area extending from inside the installation boundary, west to the Cape Cod Canal. Four gun positions and two training areas located within the Northwest Corner were used for artillery and other training, including pyrotechnic use. The site also includes a portion of the town of Bourne that was used for annual fireworks displays from 1996-2003.
Investigative activities in the Northwest Corner included soil sampling, geophysical surveys and magnetic anomaly excavations, installation of groundwater monitoring wells, and collection of groundwater samples from monitoring wells, boreholes, and private water supply wells.
A total of 70 wells were sampled. Results of this sampling indicated the presence of groundwater plumes of both perchlorate and RDX. A shallow perchlorate plume has concentrations ranging from 0.28 ppb to 26.3 ppb. The EPA Health Advisory is 15 ppb and the MA Maximum Contaminant Level is 2 ppb. The narrow RDX plume lies within the footprint of the perchlorate plume but is deeper. Concentrations of RDX have ranged from .25 ppb to 15 ppb. The EPA health advisory is 2 ppb.
The most likely origin of the perchlorate contamination in shallow groundwater is the deposition of perchlorate particles from aerial dispersal. The deposition occurred in an approximate 370-acre area that extends from the launch area for a nearby annual fireworks display, northwest to beyond gun position 16. Once perchlorate is deposited on the ground as a particulate, it readily dissolves in rainwater.
The most likely sources for the narrow RDX plume are located upgradient of the Northwest Corner, near the Former A Range. Sources of RDX at the Former A Range are unclear as RDX has not been detected in significant concentrations in soil samples, or in groundwater samples collected at the water table. However, while the exact source area cannot be identified, it is apparent that the concentrations in groundwater at the deeper depths originate within the Central Impact Area, an area with documented RDX in soil and groundwater. It is possible that the contamination in the source area has been depleted over time and the RDX plume observed in the Northwest Corner has become detached from the original source area.
In September 2004, three residential wells in the area were disconnected and the residents were connected to the public water supply operated by the Bourne Water District.
A Remedial Investigation/Feasibility Study report has been issued to evaluate remediation options for the Northwest Corner.
A Decision Document is available for this site. Click here for more information.
To obtain more information about this site, click here.
The area toward which groundwater flows
Royal Demolition Explosive; Royal Dutch Explosive; Research Department Explosive - A white crystalline solid used as an explosive
Perchlorate is a contaminant that can exist in the environment as part of other compounds also containing ammonium, potassium or sodium; approximately 90% of the perchlorate produced by US manufacturers has been for use as a rocket fuel oxidizer, and most of the remaining 10% is utilized in military and civilian explosives, munitions, and pyrotechnics (which includes items such as flares and smoke grenades)
A body of groundwater that contains contaminants in excess of amounts allowed by law; the plume is defined by multiple samples from multiple monitoring wells