Hawthorne Army Depot

HWAAP-B12
BUILDING 101-10 CATCHMENT PIT

SITE DESCRIPTION
HWAAP-B12 is an inactive unlined surface impoundment located east of building 101-10 and measures 18-ft x 18-ft x 6-ft deep. The pit is eroded and partially filled with windblown sand. Two discharge pipes enter the impoundment from the west and an additional pipe enters from the south. No piles of dredged soil are evident at this impoundment. The impoundment was in operation from 1940 to the early 1970's and received large amounts of waste water containing TNT and RDX. Ground water is estimated to be at approximately 120 feet below ground surface but has not been sampled at this site. Visible evidence of TNT-stained soils in and surrounding the impoundment was noted during investigations (1988-1992). Remedial investigation work in 1994 included surface soil and hand auger sampling and cone penetrometer (CPT) advanced to a depth of 56 feet. Three surface soil samples, one hand auger sample and two CPT soil samples were collected and analyzed for explosives and metals. Elevated concentrations of RDX (1900 mg/kg), TNB (70 mg/kg), TNT (2600 mg/kg), DNT (4.8 mg/kg) and beryllium (0.60 mg/kg) were detected in the soil. A low concentration of ammonium picrate was also detected. Investigation results show concentrations of explosives reduce significantly with depth. All the groundwater monitoring (started in 1997) for the 101 Production Area Sites - B13, B30, B20, B10, J12, B28a, A08, B26, J14, J06, and J29 (a total of 16 wells) - is now tracked under this site. Soil contaminated with explosives was treated by bioremediation in 1999. A no further action decision document for soil was signed August 4, 2000.

Aerial Photo (black & white --108KB)

PROPOSED PLAN
A Closure Decision Document was approved by the NDEP in August 2000.

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