The Double Tracks Radiological Safety Area (DTRSA), Corrective Action Unit (CAU) 486, was clean-closed following the approved Corrective Action Decision Document closure alternative and in accordance with the Federal Facility Agreement and Consent Order. The CAU consists of a single Corrective Action Site, 71-23-001-71DT. The DTRSA was used during May 1963 to decontaminate vehicles, equipment, personnel and animals from the Double Tracks Test. Double Tracks was one of four storage-transportation tests. The Double Tracks test was conducted in Stonewall Flat, approximately 32 kilometers (20 miles) east of Goldfield, Nevada, on the Nellis Air Force Range. The Double Tracks Test used a single device containing plutonium and depleted uranium and was designed to investigate the characteristics of plutonium-bearing particulate material formed by the non-nuclear detonation of a nuclear weapon. All facilities associated with the DTRSA operation were removed. Based on available information, the areas of concern at the DTRSA consisted of a decon facility (vehicle decon pad and decon sump) in the southern half of the DTRSA, and a burial pit and former loading/unloading area located in the northern half of the DTRSA. Based on the results of the Corrective Action Investigation, radiological field screening detected elevated gamma and alpha readings on excavated plastic debris. Swipe surveys taken on the plastic debris detected removable alpha. No contaminants were detected above preliminary action levels in soil samples. The debris excavated during the corrective action investigation was not characterized. The clean-closure corrective action consisted of excavation, disposal, verification sampling, backfilling, and regrading. Field activities began on May 1, 2000, and ended on May 10, 2000. Soil that was associated with the radiologically contaminated man-made debris was placed into B-25 bins, moved to the designated waste management area where it was scanned, and hauled off-site for disposal. Verification soil samples were collected and analyzed to determine if clean closure had bene achieved. Clean borrow soil was hauled to the site and used to backfill the excavation. The excavation was then regraded to promote drainage and minimize ponding of surface water. Since the site is clean-closed, post-closure care is not required.
