Site 12: Building 167 SWMUs
Site 12 (formerly designated as AOC N) is located in the northwestern portion of Plant 1, just north of Site 11. Five solid waste management units (SWMUS) are associated with Building 167, which are within Site 12. A list of the SWMUs are provided below.
Several investigations have been conducted at these SWMUs and a removal action was performed in November 2000 to remove the wastewater sump located at SWMU 37N, its contents, and potentially contaminated soil immediately surrounding the unit. The results of the investigations and post-confirmatory soil sampling indicated that several inorganic constituents and several organic constituents were present in soil above risk-based screening criteria and in groundwater above risk-based screening criteria.
During subsequent investigations volatile organic compound contamination was discovered in the alluvial aquifer and based upon these investigations it was determined AOC N be designated as a Site 12.
In 2005 a soil excavation with off-site disposal was conducted to address human and ecological risks identified in Site 12 soil. The Remedial Investigation at Site 12 was finalized in 2009. A Record of Decision (ROD) for Site 12 was signed in January 2012 (the ROD document was combined for Sites 11 and 12 because of their close proximity to each other and similar contaminants). The selected remedy for Site 12 is focused enhanced anaerobic biodegradation, monitored natural attenuation, and institutional controls. Remedial action at Site 12 took place on November 2012 and included injection of a carbon-containing material to the groundwater to treat chlorinated compounds using enhanced reductive dechlorination, in accordance with the ROD. LTM activities, including groundwater sampling, are conducted on an annual basis, and the results are documented in progress reports. Additional investigations for the VI pathway at Site 12 are anticipated to be completed prior to the next Five-Year Review.
Detailed information from previous investigations conducted at Site 12 is available in the Administrative Record.