Retardant drops, burn-ops and pyrocumulonimbus clouds: fighting the Lava Fire explained

Putting out a massive blaze like the Lava Fire is a monumental task. And there's a lot involved, from helicopter water drops, to bulldozers to hand crews cutting line. You'll hear a lot of lingo. What is a burn-op? A retardant drop? And what is a pyrocumulonimbus cloud? Firefighting experts answer these questions and explain how they fight fires like the Lava.

What's an interagency team?

Fighting the Lava Fire became a coordinated, major operation after Shasta-Trinity National Forest fire officials conferred with Cal Fire and the state interagency fire management team Sunday. The interagency team assumed control of the entire Lava Fire "incident" at 6 a.m. Monday morning.

The team is responsible for coordinating all firefighting activity, including gathering together firefighter ground teams, air support, tactics, logistics, meals, showers, sleeping arrangements, information, finance and so on, according to Michelle Carbonaro, the public information officer for the interagency team managing the firefighting effort.

Curt Warner, a supervisor for the team's Air Supply Group, shared details of on-the-ground firefighting tactics and air logistics Wednesday at incident command headquarters, located on the Weed High School campus. On-the-ground firefighters are eating and sleeping at College of the Siskiyous in Weed.

More:Lava Fire: Containment upped to 25%, crews 'starting to get a handle' on blaze

The fire appeared to be holding at around the 5,000 to 6,000 foot level just south of Diller Canyon, which appears as the large cleft down the face of Shastina. Weed and Mount Shasta City sit at the 3,000-3,500 foot levels.

From the fire's northern fire line it is moving northeast in the Bolam and Whitney Creek areas, Carbonaro said 

"It looks really good on the west side. Firefighters are strengthening the containment lines and mopping up to protect the communities,” Carbonaro reported.

Hundreds of firefighters at work

As of Thursday, Carbonaro said there are 1,273 fire personnel on the Lava Fire, an increase of 150 from the day before. Of these, there are now 26 hand crews, as well as the crews for 15 helicopters, 86 fire engines (increase of 25), 14 water tenders and five bulldozers.

The majority of personnel are used on the ground, Carbonaro said, in hand crews (up to 20 firefighters), bulldozer crews (operator and swamper), and engine crews (4-5).

More:Weed Carnevale postponed while Lava Fire continues to burn nearby

Fire engines, which hold 500 gallons, pump water through the hoses handled by firefighters. Water tenders resemble fire engines but have large tanks and aren't rigged with firefighting equipment. The trucks shuttle water to the engines. Depending on the truck, they can hold 1,000 to 2,500 gallons. Once emptied, they return to the water source and fill up again. This is usually from the city's water supply, Carbonaro said, but sometimes can be a creek, river, lake or pond.

Pyrocumulonimbus clouds: what are they?

"We're in line for a gradual reprieve in the weather, which will help a lot," Carbonaro said on Thursday. Temperatures over the next few days are forecast to drop to the mid-90s. "Even a slight drop by a few degrees help because there's less wind and the humidity increases."

But weather can also be affected by fire. One of the most dangerous aspects of fire behavior is the build up of heat, smoke and cloud into a pyrocumulonimbus cloud, which can create dangerous conditions on the ground.

More:Firefighter explains difficulty in fighting Lava Fire over dangerous, hot lava tubes

This is one of the reasons the fire team includes a fire behavior analyst and a meteorologist, who closely monitor fire and atmospheric conditions. The pyrocumulonimbus cloud can billow five miles high, and if strong enough, develop the potential for cloud collapse. This phenomenon pushes winds and heat down and out extremely fast and with completely erratic behavior, Carbonaro explained.

"When they see that a pyrocumulonimbus cloud is developing with the potential for collapse, they pull the crews immediately to a safe location."

However, there are seasoned firefighters who are also "very savvy guys" who understand changing conditions as they develop, and can call for changes in tactics to deal with them.

"Division supervisors who work under the operations chief are given an objective to complete for the day. But because they are very knowledgeable about fire behavior, they'll call for changes, both to accomplish the objective and for safety reasons," Carbonaro explained.

What's a burn-op?

"Firefighters have mottos, like, 'if you can't fight it directly, fight it indirectly'." Carbonaro said the "burn op" is an example.

With a burn-op, fire is used to fight fire.

"When you put fire on the ground, it has its own risks. So the operation requires a very carefully coordinated plan that meets the right conditions. A burn-op is usually done at night when the temperature and humidity are lower," Carbonaro said.

"You clear a line in the fuel back away from a line of wildfire," Carbonaro said. Firefighters clear brush and timber using hand tools and bulldozers, then a group ignites the brushy edge. Another group tends the fire to keep it moving toward the line of wildfire. When the two fires meet, the wildfire dies out.

Three kinds of helicopters used to fight Lava Fire

The water source for helicopters dousing Lava Fire flames is Lake Shastina. Curt Warner said the team is using three sizes of helicopters. The largest, which looks like a giant bug, holds up to 2,000 gallons of water. The water is dropped either straight down from a hovering helicopter or along a fire line from a moving helicopter.

"You drop it straight down when there's a bunch of fire deep in a canyon, or somewhere you need to pinpoint the drop,” Warner said. "But 90% of the time you drop on the fire line. The helicopter moves over it and releases the water. It works really well because water takes a lot of heat out of the fuel, which can be way too hot for the firefighters.

More:Siskiyou homeowners face loss of homeowner's insurance due to fire risk

"The helicopters keep fire in check," Warner explained. "But the fuels are pretty thick in here, and dropping water is not gonna get every little coal and ember. That's why you have to have boots on the ground, to make sure it's out. They'll make a line by hand tool or bulldozer, and then the engine crews spray it again to make sure its dead out."

Medium-sized helicopters hold about 300 gallons. They are about the size of a Huey, which are used by military for med-evac, Warner said. They are used for water drops and to transport crews and cargo.

Small helicopters are used mostly for reconnaissance, mapping and scouting, Warner said. They can hold 100 gallons of water.

For the Lava Fire, helicopters are refueling and parking at Mott Field near Dunsmuir.

Flame retardant is red at first, dye fades over time

Fixed wing aircraft – airplanes and jets – pick up flame retardant at nearby airports then make strategic drops on unburned fuel in the fire area. Warner said the retardant protects unburned fuel and keeps fire from spreading.

"Say you have a skinny road that you want to use as a fire break. You drop a line of retardant on the vegetation next to the road, to widen the break so fire can't jump the road," he said.

Warner said the retardant is a type of fertilizer, called phos-chek. "It doesn't hurt the plant life,” he said, though there is some push back against that notion, especially regarding fish and aquatic life.

Retardant is bright red when you first drop it, but after six or eight months the dye fades to where you can't see it, Warner said.

The air tankers are parked, refueled and loaded with retardant at airports in the area, "dedicated air tanker bases, with retardant set up to pump into the planes," said Warner.

'Severe criminal penalties': Don't fly your drones over a fire

All air traffic in the area of a fire is restricted by the Federal Aviation Administration, Warner said. This is done to allow the air attack pilots to focus without distraction.

"An air attack officer (with CIIMT) is in the air at all times, coordinating air traffic over the fire. It may look chaotic from the ground, but the air above a fire is actually extremely well-choreographed," Warner said.

"All (civilian) pilots are responsible to know the area is restricted. This goes for drones too. It's become a big deal because everyone who has one wants to see what's going on," Warner said. The drones are not safe because they're small, he said (about the size of a box from Amazon).

"You can't see them until until absolutely the last minute, when they hit the windshield or get tangled in the rotor. When we know a drone is in our restricted airspace, we stop all air operations.

Warner warned that violating air restrictions can result in severe criminal penalties.