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Tiny balls of fire

Tiny balls of fire

Firefighters hurled pingpong balls at the Timbered Rock fire Monday in a high-tech effort to contain one of the last unsecured sectors of the 27,000-acre wildfire.

A helicopter flitted over smoky ridges on the north side of the fire, dropping tiny incendiary plastic spheres on the hills above Elkhorn Creek, north of Trail. The balls burst into flame as they reached the ground. Firefighters hope the fires they started will consume unburned materials in an 800-acre pocket between the fire and the containment line.

Firefighters deliberately set fire to unburned areas between the fire and the containment line to reduce the chances that the flames will flare up and jump the lines. The timbered ridges above Elkhorn Creek are some of the last areas they need to burn out to meet their goal of containing the fire on Wednesday.

We're controlling fire with fire, said Rick Rogers of Eugene, who supervised the aerial burnout. That's the only way we get ahead of these large fires.

Usually firefighters set fire to unburned areas inside the line on foot, starting fires with a mixture of diesel fuel and gasoline or flares known as fusees. Fire bosses occasionally call for a helicopter to deliver fire to areas that are too hazardous for firefighters to do the burning out on the ground.

The aerial fireballs have been used for years on slash burns, but less frequently in fire suppression. They were deployed last week on the Florence fire in Josephine County.

The 1&

188; -inch balls are filled with potassium permanganate, a material that ignites in the presence of ethylene glycol (automobile antifreeze). The chemical reaction yields flames within about 20 seconds, usually just after the balls reach the ground.

The old-growth timber on the slopes above Elkhorn Creek had more than enough potential hazards to justify using the little balls of fire, said Rick Rogers, who coordinated the aerial burn-out.

It's very steep up there, Rogers said. There are old-growth snags falling everywhere. There are no escape routes (if the fire flares up), and people on the ground would have big trees burning above them.

Rogers said the balls' delayed-ignition feature make them especially suitable for use in the old-growth timber on Elkhorn Creek, where firefighters want to burn woody debris on the ground without burning the trees.

The balls will actually drop through the canopy before they ignite, said Rogers. We just need to get the fuel down under the canopy.

Fire bosses called on Steve and Wayne Roberts of McMinnville's Terra Helicopters to deliver the aerial assault on a day when the fire had largely died down. Pilot Steve Roberts set off for Elkhorn Creek in a little Hughes 500-D helicopter loaded with hundreds of balls and an aerial ignition dispenser, a machine that automatically injects a prescribed amount of antifreeze into each one just before it leaves the helicopter.

Pilots fly with care to be sure the balls don't land in unburned areas on the green side of the fire line, where they could start new fires.

It's not unusual to fly on the far (unburned) side of the fire line, Wayne Roberts said. The wind will drift them over onto the burned side of the line.

The helicopters fly close to the tops of trees ' often within 50 to 100 feet ' to minimize wind drift. Fuels on the ground determine how many balls they drop with each pass, Wayne Roberts said. South-facing aspects with flashy fuels (grasses) will go up faster. North slopes won't burn as aggressively.

late afternoon, the Roberts' helicopter had made several passes over Elkhorn Creek and filled the drainage with smoke as small fires broke out and crept along the forest floor. The little fires will probably continue to burn toward containment lines today, fire information officer Howard Hunter said.

High humidity and unseasonably cool temperatures that were expected to continue today will help keep the fire on the ground, where firefighters want it, said Hunter, who works for the Medford District of the Bureau of Land Management.

We should have a creeping fire, he said. We'll probably have 500 little fires that will warm up (today) and crawl around.

Hunter said firefighters will fly over the burn area with infrared cameras today to determine how far the fires have crept.

Reach reporter Bill Kettler at 776-4492, or e-mail

A Hughes 500-D helicopter drops little incendiary balls on the Timbered Rock fire north of Trail on Monday. The balls set fire to unburned material between the fire and the containment line. Mail Tribune / Bob Pennell - Mail Tribune Bob Pennell