Trailer likely cause of Silver Lake fire

Fire investigators have tabbed burning material from a vehicle as the likely cause of last week's Silver Lake fire that burned 345 acres of grass and timber land between Interstate 90 and Granite Lake Road three miles northwest of Cheney.

State Department of Natural Resources Northeast Region senior wildland fire investigator John McDonald said on Monday, Aug. 13, this definition ranges from carbon particles discharged in diesel exhaust to a dragging chain to parts coming off a vehicle. The Silver Lake fire was likely started by the latter.

"In this case, it was a wheel hub, a tire came off a trailer around the east end of the 265 (Salnave Road/State Route 902) exit," McDonald said.

McDonald said they found a tire, wheel hub and other debris from a two-axle utility trailer near the ignition point of the southern end of the fire. The fire originally started on Aug. 6 at four points along I-90 between Salnave Road exit 265 and just short of Four Lakes exit 270, but eventually merged into two fires along the interstate.

Eventually 126 firefighters from 11 different agencies, including four DNR wildland strike teams and units from Spokane County Fire District 3 and the Medical Lake Fire Department, were involved in combating the blaze. Also helping were eight aircraft, including six Fire Boss planes, that benefited from short turn-around times by refilling with water from nearby Silver Lake.

McDonald said it's difficult to pinpoint ignition causes of fires that occur along roadways due to the high amount of debris that can be found alongside. Without an actual trailer with which to associate the debris found near Salnave Road, it's doubtful the investigation into the Silver Lake fire will go much further.

"After the fire broke out, I asked Washington State Patrol to look for any broken down vehicles in the area while I was en route from Colville," McDonald said. "They didn't find any."

Despite low humidity and temperatures that topped 100 degrees last Thursday and Friday, firefighters were able to get a relatively quick handle on containing the fire and preventing its spread. Initially reported at 100 acres, the fire's size grew internally rather than outside the containment lines, with flare ups limited to spot fires in unburned areas and some slash piles overnight Tuesday and into Wednesday.

Mapping of the fire on Aug. 9 showed 11 miles of fire line around the two fires, which according to the day's fire update report "is an unusually high amount of fire line around a fire of this size."

"I don't know if I could give you a typical amount, but if this fire was a rectangle, we would only have about three miles of fire line," Guy Gifford, DNR's Northeast region land owner assistance forester/fire prevention and Firewise coordinator said in a Aug. 9 email.

"But it is very long and skinny, so a lot of fire line had to be put in," Gifford added. "From a fire fighting standpoint, we often have a goal of mopping up 100 feet in from (the) fire edge. So, now we have 11 miles of line to do that on."

Much of this was done with hand crews, although firefighters received help from an excavator brought in on Aug. 9 to assist with extinguishing several logging slash piles.

As of the Aug. 13 update, the fire was 85 percent contained, with 100 percent expected by the end of the day. One outbuilding was destroyed, but 100 homes and 121 mixed structures were threatened at one point.

According to a report from the State Patrol's Fire Protection Bureau emergency operations center, the Silver Lake fire cost an estimated $425,000, with $300,000 coming in mobilization costs.

John McCallum can be reached at [email protected].