CENTRAL TEST AREA
SITE DESCRIPTION:
The Central Test Area was used to test fire hand grenades, adaptor boosters, and aerial mines. Very little historical documentation is available on this particular site, but layout drawings are dated back as far as 1943. It is not known exactly when this area was in operation.
Detonations were performed in the field north and east of the Central Test Area. Steel fixtures still exist at this site. Historical documentation indicated that this area is 800 ft northeast of the Central Test Area laboratory.
Approximately 500 ft northwest of Line 4A and 1,200 ft south of Line 5B, but still within the fence line of Line 5, lies Building 600-84. This building was constructed in 1941 and is considered part of the Central Test Area. The walled-in area northeast of the building was used as a test site for the inside charge of grenades. This charge was composed of lead styphynate, black powder, and tetryl booster. The outer charge was TNT and RDX.
A test pit existed approximately 815 ft to the northeast of Building 600-84. The test pit was approximately 9 ft x 14 ft with wooden walls covered by steel plates. The floor was earthen with a concrete walkway. A concrete pedestal capped by a steel plate was anchored in the floor of the pit. Soil was sloped up the walls to a height of approximately 5 ft. An operator’s building was located 105 ft southwest of the test-fire pit. Only limited information about the operations in this pit can be found.
A small area to the west of the test pit area contains a metal triangular stand or tripod used to hold components to be test detonated.
During the historical site assessment, it was determined there was a potential UXO concern at this site.
The geophysical survey field work was completed in 2004 to evaluate the potential for UXO.
This site was previously included in OU-4, but was transferred to OU-1 as documented in the Final ESD for Addition of Environmental Protectiveness to the Remedy and Transfer of Sites from OU-4 to OU-1 dated June 2008.
CLEANUP STRATEGY:
This site is included in the PBC awarded in 2004.
The soil contaminated with explosives and/or metals at this site have been successfully completed by excavation, in accordance with the RAOs established in the final ROD to protect human health and the environment. Any contaminated soil under the infrastructures of IAAAP, and therefore inaccessible, was left in place. Once confirmation samples determined that all accessible contaminated soil had been removed, each excavation was backfilled with clean soil to the original grade, compacted, and then reclaimed to original conditions. All excavated soil was transported to Trench 6 in the IDA for later treatment. A total of 239 cy of contaminated soil was removed from the CTA in the Fall of 2006.
This site is considered Response Complete (RC) as of September 2007 as documented in the Remedial Action Report for OU1 Soils Phase 5, 7, and 8 Sites and Installation Wide Ecological Evaluation.
A revised draft OU3 RI/FS was submitted to EPA for review in April 2008 to address groundwater; the recommendation for groundwater is either “No Further Action” or “institutional controls, monitored natural attenuation, and long term monitoring” depending on the selected risk level.
MEC and MC will be addressed under the MMRP.