The Clark County Fire Marshal’s Office has ruled that spontaneous combustion caused a giant slash pile fire in a rock pit northwest of Battle Ground.
Deputy Fire Marshal Caleb Barnes said the pile is still smoking, but the fire has been under control since early Sunday morning.
The fire was reported at 10:25 p.m. Saturday in a rock pit at 24810 N.E. 92nd Ave., in the Cherry Grove area.
Firefighters from multiple agencies arrived to find flames climbing from a large pile of stumps and other logging slash. The estimated size of the fire was 90 feet by 100 feet by 40 feet tall, containing about 100 cubic yards of material.
It took responders until about 3 a.m. to get the fire under control, Barnes said. Since then, someone has been watching over the pile, he said.
In general, spontaneous combustion or heating happens when moisture gets into compact organic material, and heat and wind combine to trigger smoldering. Materials can smolder for days before the right amount of oxygen is added to the mix and a fire ignites.
“It happens when environmental conditions are just right,” Barnes said. “We see it a lot in bark dust fires. Those may be caused by discarded smoking materials, but it’s also not uncommon for something to spontaneously heat up or combust.”
There is no monetary estimate for the damage caused by the Cherry Grove pit fire, as the burnt materials were vegetation. However, Barnes said the property owner had planned to develop the area, and the fire has halted that potential financial gain.
