Saturday, August 26, 2017

Record year for fire retardant at Redmond Air Tanker Base: Planes used locally include super-sized DC-10

Central Oregon fire managers have set a new record this season, loading more than 1.3 million gallons of fire retardant at the Redmond Air Tanker Base.

Kassidy Kern, spokeswoman with the Deschutes National Forest, said planes loaded with the retardant chemical have flown 537 missions this year, dropping their payloads on fires across Central and Eastern Oregon.

Kern said the bulk of the retardant was used on the region’s larger fires — the Cinder Butte fire between Bend and Burns, the Nena Springs Fire on the Warm Springs Reservation, and the Whychus Fire and the still-burning Milli Fire near Sisters.

The prior record of 1.2 million gallons was set in 2002, the year the Biscuit Fire burned nearly 500,000 acres in Southern Oregon and Northern California. On average over the past 10 years, the tanker base has gone through 640,000 gallons a year, Kern said.

More retardant has been brought in to Redmond for the remainder of the fire season, but retardant-dropping planes have been grounded in recent days due to the heavy smoke in the region.

Retardant is primarily water, with the dry component brought in and mixed with water at the Redmond Air Tanker Base. The nonwater portion of the mixture is about 15 percent of its total weight and consists primarily of fertilizer, Jennifer Jones of the National Interagency Fire Center in Boise, Idaho, said, along with chemicals to encourage even disbursement and colorant to allow firefighters to better see where it has been applied.

Fertilizer-based retardant can be highly toxic to fish and other aquatic life, Jones said, and the Forest Service has developed maps in order to avoid dropping retardant within 300 feet of a waterway or body of water or in areas with sensitive land-dwelling species. In the event of a fire that presents a pressing threat to human life, a fire manager can request retardant drops in areas where such drops would otherwise be avoided.

The Forest Service uses three different categories of planes to drop retardant, classified by the size of the payload they can carry. The smallest carry less than 1,000 gallons per mission, while the typical retardant plane carries a payload of between 3,000 and 5,000 gallons.

The biggest planes in the fleet, the VLAT — for Very Large Air Tanker — can carry upward of 8,000 gallons of retardant but are too large for the runway at the Redmond Airport. Tanker bases in Medford and Moses Lake, Washington, serve the largest planes when they fly missions in the Northwest.

Jones said because planes depositing long red plumes of retardant are one of the most visible aspects of fighting wildfires, observers often have misconceptions about their role in fighting fires.

Retardant is used on less than 10 percent of fires, and the Forest Service’s fleet of more than 100 water-dropping helicopters does many more flights than the 28 air tankers in service.

Although the retardant plume released by an air tanker resembles the discharge from a home fire extinguisher, it serves a different function. Jones said retardant is not particularly effective in knocking down flames but is instead dropped in the predicted path of the fire. Vegetation soaked with retardant will still burn, she said, but it burns cooler and slower, giving firefighters on the ground more time to dig lines with bulldozers, chainsaws and shovels.

Kern and Jones both said there’s been no change in firefighting tactics leading to the boost in retardant use this year, and that the decision to call in retardant drops rests with the on-the-ground fire managers.

“Aerial resources are great to have, they really are, but a fire will be won on the ground,” Kern said.

Original article can be found here ➤

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