Record of Technical Change 1 for Closure Report for Corrective Action Unit 543: Liquid Disposal Units, Nevada Test Site, Nevada, Revision 0

Abstract

ROTC-1: Downgrade FFACO UR at CAU 543, CAS 06-07-01, Decon Pad to an Administrative UR. CAS 06-07-01, Decon Pad, is located at the Decontamination Facility in Area 6. The CAS consists of the effiuent collection and distribution systems for Buildings 6-605, 6-606, and 6-607, which include two 1,000-gallon (gal) septic tanks, two ground-level sumps and associated piping, the concrete foundation of Building 6-605, floor drains, drain trenches, and cleanouts. The Area 6 Decontamination Facility was built in 1971 and was designed to decontaminate vehicles, equipment, and clothing that had become radiologically contaminated during nuclear testing activities. Additionally, the facility managed mixed and radioactive waste generated from these decontamination processes. The Area 6 Decontamination Facility is located along the southwest edge of Yucca Lake in Area 6 of the NNSS. From 1971through1992, hazardous, radioactive, and sanitary wastes were generated within several buildings and originally discharged via process waste lines, septic systems, and sumps to the Area. 6 Decontamination Pond. The Area 6 Decontamination Facility remained operational until 2001, and is currently inactive and abandoned. Additionally, a portion of the facility yard was used as a contaminated materials storage area where equipment and materials awaited decontamination. As a result, portions of the facility yard are posted as "Contamination Areas" (NNSA/NSO, 2004d). During closure activities, the use-restricted area was fenced and posted, and a UR was implemented for PCBs and radioactivity. As best management practices (BMPs ), two septic tanks, two sumps, and their contents were removed and disposed of as mixed waste; sediment from the Building 6-605 floor drain trenches was removed and disposed of as mixed waste; the floor drain trenches, a diversion box, and seven cleanouts were grouted to grade; and numerous containers and other surface debris were segregated according to waste stream and disposed of appropriately as either low-level waste or sanitary waste (NNSA/NSO, 2008). ·