Rulison Occurred at 3:00 pm September 10, 1969 Doghead Mountain (south of Rulison, CO) Result : 8000 ft under Dog mountain a cavity 42m in diameter and 164 m high remains contining 20,000 metric tons of radioactive rubble (including plutonium). There is little indication that this site is being monitored. AE Systems, California Notes this and other US radioactive sites. A similar project at Rio Blanco occurred in 1973. 3 - 30 kiloton bombs The resulting blasts were designed to freeup natural gas which many suspect is being removed and sold on the open market.. Recommended Reading: American Ground Zero;