BEND, Ore. - It may be irony, or it may just be the convergence of science (spontaneous combustion), and ever-changing market forces that brought fire crews back to Knott Landfill in southeast Bend Sunday, where large piles of collected yard debris – a program aimed at reducing wildfire risks around homes – keeps bursting into flame.
The fire in the large pile of small branches, pine needles and the like was reported around 2:30 p.m., and Deschutes County landfill crews with heavy machinery had it pulled apart, wetted down and pretty much put out within an hour.
Project Wildfire's successful FireFree program has brought many thousands of cubic yards of yard debris to the landfill twice a year for free or half-price, each year for many years now – a goal of making the areas around homes "defensible space" and less vulnerable to wildfires
In the earlier days, the material was ground up to go into an on-site composting operation and would "get processed pretty quickly" into the material great for lawn cover and the like, landfill Operations Manager Chad Centola said Sunday.
But as the compost program got more popular, they ran out of room, and Deschutes Recycling could not take it off their hands, Centola said.
Then there was a program to truck the yard debris – too large or two fine for compost – off-site to serve as "hog fuel," to produce electricity for mills, Centola said.
"Some tax incentives made it profitable for them to take what was called ‘low-BTU' material" for that use, he said – but then those incentives "went away three years ago."
"Now we grind it up and use it as alternate daily overnight cover" for the active trash-disposal area of the landfill, Centola said.
The "challenge," he said, is that far more material is on site than can be quickly used up for that purpose, he said.
"The piles end up staying here so long, occasionally we have spontaneous combustion," Centola said after the third fire call in less than a week to one of the three or four landfill mulch piles located around the property.
The first such fire occurred two years ago, Centola said. This year, a dry fall has been causing problems, and "the wind doesn't help," he added.
They haven't come up with a good solution, the landfill manager said, adding that dumping it in the landfill itself and burying it could just cause more problems with spontaneous combustion.
Centola said crews on Sunday "dug out the area we're having the problem with, spread it out no thicker than 12 inches (deep). They guys are out there watering the heck out of it right now."
But he noted: "Once this stuff gets that hot, putting water on it is a double-edged sword, as it can speed the decomposition that generates the heat."
"We're going to have a long discussion about what, if anything we can do," Centola said. "I'm not sure who else has something like FireFree and a successful compost operation. Now that compost is at capacity, and FireFree is rolling along on its own" – the issue has taken shape.
One possible solution would be if the county concludes a deal with a California firm that wants to generate power from methane produced by decomposing garbage at the landfill. One option on the contract could add a biomass program, which might make use of the yard debris.