BA-4 Disposal Area
The BA-4 Disposal Area consists of two acres located at Pew and Pocasset-Forestdale Roads. Portions of the BA-4 Disposal Area fall within the larger A-3, A-5 BA-4 and A-4 training areas. The site includes five areas of 2,500 to 6,500 square feet each (labeled Area A-E) and areas adjacent to, but just outside Areas A-E, that were investigated as potential disposal sites. The remainder of the BA-4 area outside of the disposal area is still under investigation.
The BA-4 Disposal Area investigation was part of a survey to look for former disposal sites. Following geophysical surveys in 2001, 82 anomalies from Areas A through E were excavated to look for potential disposal sites. The materials recovered in Areas B, C, and D included miscellaneous metallic debris such as nails, beverage cans, ammunition cans, railroad material, structural reinforcing bars and packaging material. One practice grenade was recovered from Area D.
Additional investigations conducted Areas A and E included 46 magnetic anomalies. A disposal site containing 312 expended jet starter-cartridges and igniter-tubes was found in Area A, and a 55-gallon drum of ash, burnt small arms and pyrotechnics, was found in Area E. These items and the surrounding soil were removed and disposed of off site.
Based on soil sample results a rapid response action was conducted in Areas A and E, starting in 2006. This action removed approximately 85 tons of soil containing lead contamination from Area A and a total of 10.5 tons of soil containing dioxins from Area E. Additional geophysical investigations also were conduced in areas adjacent too, but outside of the original five areas. The soil and other items were disposed of off site. Confirmatory soil sampling results confirmed no further soil removal was necessary in either area.
There have been no detections of contaminants in groundwater related to the BA-4 Disposal Area. There have been no detections of site-related contaminants in two groundwater monitoring wells located approximately 4,000 feet downgradient since they were installed in 1999. Lead above the state drinking water action level of 15 ppb was detected in a decommissioned pumping well located at the BA-4 Disposal Area, however this appears to be related to metal well construction materials. Similar detections were not seen in a new pumping well installed in that area in 2002, a groundwater monitoring well (MW-469M1) installed at the location of the older well or at another drive point and driving well placed downgradient of soil contamination in Areas A and E.
Based on investigation findings and the removal of contaminated soil, the EPA has proposed a No Further Action Decision Document for the BA-4 Disposal Area.
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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