LAS VEGAS — Nevada agencies are moving toward finding fault and a fix following an explosion and fire at a long-closed radioactive waste dump northwest of Las Vegas, the state’s top cop said Thursday.
Public Safety Director Jim Wright declared the police investigation finished after state Fire Marshal Peter Mulvihill submitted his findings Wednesday about the Oct. 18 incident.
The report said rainwater from unusually heavy storms drained through cracks in a trench cover mound and seeped into corroded 1970s-era barrels before reacting violently with metallic sodium at the site about 12 miles outside the Nye County town of Beatty.
Mulvihill reported that the material that exploded was from a closed U.S. Bureau of Mines facility in Boulder City, east of Las Vegas. It wasn’t radioactive.
No injuries were reported and no radiation was detected by first responders, investigators or repair crews after the blast. Nearby U.S. 95, the main highway between Las Vegas and Reno, was closed for several days while radiological readings were taken.
Repairs were made in the weeks that followed, and several 55-gallon drums that had been blown beyond the fence were returned to the crater and reburied. The damaged area was filled with dirt and covered with a waterproof chemical membrane, Mulvihill said.
Wright said the investigation is now in the hands of state Radiation Control and Department of Environmental Protection officials.
“We know what caused it,” the public safety chief said. “A follow-up report will be done by rad waste and DEP. Was the material allowable? What is the long term corrective action for the site?”
Department of Environmental Protection spokeswoman JoAnn Kittrell said her agency was assisting health officials in the radiation waste office. The radiation official handling the investigation wasn’t immediately available for comment Thursday.
Vance Payne, Nye County emergency operations chief, welcomed progress in the probe. The state of Nevada owns the land and is responsible for the 80-acre site.
“Even with the marshals’ report, we’re still waiting for other reports to come in,” Payne said. “What we don’t have right now is the overview.”
The federal Energy Department and Nuclear Regulatory Commission and the Desert Research Institute of the University of Nevada are among other entities involved in the probe.
The dump opened in 1962 as the nation’s first federally licensed low-level solid radioactive waste repository for waste such as contaminated tools, protective clothing, machine parts, medical items and laboratory supplies. It closed in 1992. Records say the 40-acre property consists of 22 trenches up to 800 feet long and 50 feet deep.
The dump was operated by US Ecology Inc., which still operates a plant to treat, recycle and dispose of hazardous and nonhazardous waste on an adjacent 40 acres of state property.
US Ecology says records show the material in the trench that exploded was buried between 1969 and 1973.
Mulvihill said the drums had contained oil to prevent water from reaching the metallic sodium, but the oil leaked out over the years and water got in.
The fire marshal said tests confirmed that a fine white powder collected from around the blast crater was sodium hydroxide dust — one byproduct of the violent chemical reaction that also produces heat and hydrogen gas.