EPHRATA — A yet-to-be-determined failure on a line near Columbia Basin Hospital Feb. 17 triggered the failure of and an arcing explosion in a transfer station in Ephrata. Grant County PUD commissioners were updated on the investigation into the incident at their meeting Monday.

The preliminary timeline shows something happened on a line near the hospital, said Julie Pyper, leading the investigative team. “We’re still determining the root cause for that,” she said. “Best estimate that we have is about a 2-second fault.”

The failure caused damage to a transformer, then hit the substation, next to the railroad tracks in Ephrata. The electrical arcing at the substation lasted about 3 minutes, Pyper said. “A 3-minute fault, from what the engineers are telling me, is a very long time.”

The arcing transformer set fire to an adjoining building, damaged and destroyed nearby equipment. The building housed an office and shop, and the office was badly damaged, she said.

The transformer fire cut power to about 8,000 customers, at least briefly, said PUD public information manager Thomas Stredwick at the time of the incident. Service was restored to some customers within 90 minutes, but electricity wasn’t completely restored until about 1 p.m. Feb. 18.

The root cause is still under investigation, Pyper said. In answer to a question from commissioner Tom Flint, she said a report should be issued by mid-April.

The substation is still shut down. The damaged parts will be tested to see if they can be salvaged.

In the meantime PUD engineers are working to determine if the system can handle peak loads in the summer without the substation, Pyper said. Utility district administrators are planning to build a new substation in south Ephrata, and part of the discussion is how the new substation will mesh with possible repairs to the existing in-town substation.

“That substation (in Ephrata) has been there a long time, and the conditions have changed dramatically since it first went in – I’m assuming you’re looking at whether or not it’s in the right spot or not,” Flint said. That’s one of the questions under discussion, Pyper said.

Commissioner Terry Brewer asked about a construction timeline for the south Ephrata substation. That too is part of the discussion, Pyper said. “In short, we don’t have a timeline.”

The PUD has a mobile substation that’s been pressed into service. Flint asked about its useful life and how long the PUD has owned it. He asked if the PUD needed another one, given the changes in PUD customers and electrical loads. General manager Kevin Nordt said that was under discussion as part of the long term planning process.

Cheryl Schweizer can be reached via email at [email protected].