AP, Nov 16, 2015: The last of six men treated for burns at a Seattle hospital after an electrical explosion at a hydroelectric dam on the Columbia River has been discharged… Officials have said the explosion at the Priest Rapids Dam was caused by an electrical equipment malfunction.
Seattle Times, Oct 12, 2015 (emphasis added): State authorities are investigating the cause of the explosion at the Priest Rapids Dam… Chuck Allen, a spokesman for Grant County PUD, said the Washington Department of Labor and Industries is investigating the incident. The PUD is conducting an internal investigation as well, he said. Those examinations likely won’t be finished for several weeks. “[The explosion] obviously was very significant,” Allen said. “But as far as the scope and the scale, we don’t have that yet.”
NPR, Oct 9, 2015: ‘Arc Flash’ Likely Behind Explosion At Priest Rapids Dam — A surgeon at Harborview Medical Center in Seattle said the serious burns to five electricians and dam operators injured in Thursday’s explosion at Priest Rapids Dam in central Washington are consistent with “arc flash.” Pacific Northwest National Lab‘s chief electrical engineer Jeff Dagle explained an arc flash results from a short circuit involving high-voltage electricity. “That current generates a tremendous amount of heat and that heat creates a plasma — high temperatures and expanding gases,” Dagle explained. Dagle said lightning is the same type of phenomenon. The Grant County Public Utility District said the explosion happened in the dam’s powerhouse. Two dam workers remain in intensive care with “large burns” at Harborview.
Tri-City Herald, Oct 9, 2015: A breaker for one of the 10 generators at the dam malfunctioned, said PUD spokesman Chuck Allen… “When the switch malfunctioned, a large amount of electrical energy was released,” Allen said. The injured workers were nearby. The cause of the malfunction was not known Friday. The dam [is] near Desert Aire on the Columbia River upstream from Hanford… Investigators from Washington State Department of Labor & Industries were at the dam Friday to evaluate events leading up to and causing the incident. Results of the investigation will likely take weeks, according to Grant PUD. It also is conducting its own investigation… A power outage was reported after the explosion, which affected some cell towers. U.S. Cellular customers lost phone service…
OPB, Oct 8, 2015: Utility district spokesman Thomas Stredwick… said the structure of the dam is stable and no one down the river is at risk. Multiple agencies have responded to the incident including the Hanford Fire Department… The Labor and Industries investigation is expected to take several weeks.
Seattle Times, Oct 9, 2015: Officials said the blast caused some electrical power and cellphone outages. Kyle Foreman of the Grant County Sheriff’s Office, one of the agencies looking into the incident, said investigators found no connection between the explosion and terrorism or criminal activity. Grant Public Utility District spokesman Thomas Stredwick said the size of the explosion and its damage were unknown… A huge crack in [in the nearby] Wanapum Dam, posed a risk of failure and prompted the creation of an emergency-response plan last year.
Published: December 1st, 2015 at 4:40 am ET