Corrective Action Unit 485, Corrective Action Site TA-39-001-TAGR, the Cactus Spring Ranch Soil Contamination Area, is located approximately six miles southwest of the Area 3 Compound at the eastern mouth of Sleeping Column Canyon in the Cactus Range on the Tonopah Test Range. This site was used in conjunction with animal studies involving the biological effects of radionuclides (specifically plutonium) associated with Operation Roofer Coaster. The location had been used as a ranch by private citizens prior to government control of the area. According to historical records, Operation Roofer Coaster activities involved assessing the inhalation uptake of plutonium in animals from the nonnuclear detonation of nuclear weapons. Operation Roofer Coaster consisted of four nonnuclear destruction tests of a nuclear device. The four tests all took place during May and June 1963 and consisted of Double Tracks and Clean Slate 1, 11, and 111. Eighty-four dogs, 84 burros, and 136 sheep were used for the Double Tracks test, and ten sheep and ten dogs were used for Clean Slate 11. These animals were housed at Cactus Spring Ranch. Before detonation, all animals were placed in cages and transported to the field. After the shot, they were taken to the decontamination area where some may have been sacrificed immediately. All animals, including those sacrificed, were returned to Cactus Spring Ranch at this point to have autopsies performed or to await being sacrificed at a later date. A description of the Cactus Spring Ranch activities found in project files indicates the ranch was used solely for the purpose of the Roofer Coaster tests and bioaccumulation studies and was never used for any other project. No decontamination or cleanup had been conducted at Cactus Spring Ranch prior to the start of the project. When the project was complete, the pits at Cactus Spring Ranch were filled with soil, and trailers where dogs were housed and animal autopsies had been performed were removed. Additional pens and sheds were built to house and ...