This Corrective Action Investigation Plan contains the U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office's approach to collect the data necessary to evaluate corrective action alternatives appropriate for the closure of Corrective Action Unit (CAU) 528, Polychlorinated Biphenyls Contamination (PCBs), Nevada Test Site (NTS), Nevada, under the Federal Facility Agreement and Consent Order. Located in the southwestern portion of Area 25 on the NTS in Jackass Flats (adjacent to Test Cell C [TCC]), CAU 528 consists of Corrective Action Site 25-27-03, Polychlorinated Biphenyls Surface Contamination. Test Cell C was built to support the Nuclear Rocket Development Station (operational between 1959 and 1973) activities including conducting ground tests and static firings of nuclear engine reactors. Although CAU 528 was not considered as a direct potential source of PCBs and petroleum contamination, two potential sources of contamination have nevertheless been identified from an unknown source in concentrations that could potentially pose an unacceptable risk to human health and/or the environment. This CAU's close proximity to TCC prompted Shaw to collect surface soil samples, which have indicated the presence of PCBs extending throughout the area to the north, east, south, and even to the edge of the western boundary. Based …

This Corrective Action Decision Document identifies and rationalizes the U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office's selection of recommended corrective action alternatives (CAAs) to facilitate the closure of Corrective Action Unit (CAU)168: Areas 25 and 26 Contaminated Materials and Waste Dumps, Nevada Test Site (NTS), Nevada, under the Federal Facility Agreement and Consent Order. Located in Areas 25 and 26 at the NTS in Nevada, CAU 168 is comprised of twelve Corrective Action Sites (CASs). Review of data collected during the corrective action investigation, as well as consideration of current and future operations in Areas 25 and 26 of the NTS, led the way to the development of three CAAs for consideration: Alternative 1 - No Further Action; Alternative 2 - Clean Closure; and Alternative 3 - Close in Place with Administrative Controls. As a result of this evaluation, a combination of all three CAAs is recommended for this CAU. Alternative 1 was the preferred CAA for three CASs, Alternative 2 was the preferred CAA for six CASs (and nearly all of one other CAS), and Alternative 3 was the preferred CAA for two CASs (and a portion of one other CAS) to complete the closure …