Streamlined approach for environmental restoration closure report for Corrective Action Unit 454: Historical underground storage tank release sites, Nevada Test Site, Nevada

This report addresses the characterization of three historical underground storage tank (UST) petroleum hydrocarbon release sites identified as 12-B-1, 12-B-3, and 12-COMM-1. The sites are located within the Nevada Test Site in Area 12 at B Tunnel and a former Communications/Power Maintenance Shop. Release Site 12-B-1 was not able to be clean-closed as proposed in the SAFER Plan. However, hydrocarbon impacted soils were excavated down to bedrock. Release Site 12-B-3 was evaluated to verify that the identified release was not associated with the UST removed from the site. Analytical results support the assumption that wood or possibly a roof sealant used as part of the bunker construction could have been the source of hydrocarbons detected. Release Site 12-COMM-1 was not clean closed as proposed in the SAFER Plan. The vertical extent of impacted soils was determined not to extend below a depth of 2.7 m (9 ft) below ground surface (bgs). The lateral extent could not be defined due to the presence of a discontinuous lens of hydrocarbon-impacted soil