Arc flash declared cause of Priest Rapids Dam explosion

DESERT AIRE — An arc flash triggered by the failure of a circuit breaker caused the explosion that injured six workers at Priest Rapids Dam, just south of here, on Oct. 8.

Two of the injured remain hospitalized at Harborview Medical Center in Seattle. Both were in serious condition at last report.

The arc flash occurred on the P8 generator, “which has between 13.2 and 13.8 kilowatts, about 100 times more voltage than a common household outlet,” said Chuck Allen, public information specialist for the Grant County PUD.

An arc flash occurs as the result of an arc fault, according to the National Electrical Manufacturers Association. An arc fault is “an unintended arc caused by current flowing through an unplanned path.”

According to the federal Occupational Safety and Health Administration. An arc flash “leaves its intended path and travels through the air from one conductor to another, or to ground.”

The two workers still hospitalized are undergoing surgery for their burns, according to information from Harborview. Both are men in their 40s.

Of the six originally injured, one was treated and released within 24 hours of the explosion, while the other five were airlifted to Harborview. Three have since been released. All are dam operators or electricians.

The investigation is still underway, Allen said. The Washington Department of Labor and Industries is conducting a parallel investigation into the accident, but there’s no timeline for release of the findings in either investigation.

A fund to help the families of the victims has been opened at Granco Federal Credit Union, 217 Southwest Alder St., Ephrata. Donations can be mailed to the credit union at PO Box 127, Ephrata, WA 98823. Donations should be marked “Priest Rapids Family Fund.”

Friends of Michael Stalcup, one of the victims, set up a GoFundMe account for the family. It had raised about $3,000 through Monday.

Stalcup’s wife Stephanie has provided updates on the GoFundMe page, and said Stalcup has undergone some surgery to remove debris from his skin and repair burned tissue. With luck it will be the only surgery required, Stephanie Stalcup wrote.

Messages of support can be emailed to the victims. The address is www.uwmedicine.org/patient-resources/email-patient. People who don’t have the patients’ names can identify the email with “dam explosion patients in intensive care.”