KANOSH, Millard County — Vehicles flew past Manderfield, Beaver County, on I-15, and maybe a few drivers saw a puff of smoke in the distance. In nearby mountains, an intense blaze burned, throwing flames 30 feet into the air.
It was a "backburn," ignited by firefighters to char a small valley west of the highway in hopes that the state's largest fire in history, the Milford Flat fire, will cease to spread to I-15 if the flames don't have vegetation to fuel them.
The backburn — which began at 5 p.m. Thursday and will continue to smolder through the night — helped contribute to the fire's 65 percent containment, with full containment estimated for Tuesday.
By Thursday night, the fire had consumed 363,052 acres.
That's up from 351,549 acres Wednesday. But Rowdy Muir, commander of the Great Basin Type 1 National Incident Management Team, said the size increase is more a result of better mapping than actual fire growth.
Crews on Wednesday "didn't fly (over) it because it was real windy and smoky," he said.
Costs to fight the fire have been $2.6 million so far. The Federal Emergency Management Agency will reimburse the state 75 percent of its costs.
Lower temperatures, combined with high humidity, helped tame the fire, Muir said. Humidity was about 20 percent Thursday, compared with Sunday's 4 percent. Temperatures were in the mid-90s on Thursday, while they had hit nearly 100 degrees at the beginning of the week.
Muir, however, doesn't expect the better weather to last. "It's going to warm up at the end of the week," he said.
Containment was made on all flanks of the fire, team fire information officer Vince Mazzier said.
The backburn occurred on the south side of the fire, about eight miles from the town of Manderfield and six miles west of the freeway. A "hotshot crew" of 20 firefighters from Idaho City, Idaho, used "drip torches" that contained a diesel-gasoline fuel mix and had a spout.
As the firefighters poured the mixture, the terrain ignited. The hotshots started at the top of the small canyon and made their way down the steep, rocky hillsides, carefully lighting oak, cheat grass, pinyon-juniper and mountain mahogany.
Some areas were so thick with foliage that the hotshots feared they would be unable to safely escape, so they used flare guns, which shoot flares 50 to 100 yards away.
Black, white and orange smoke rose above the flames. Black smoke billows from the burning of heavy fuels, such as trees, fire information officer Linda Holz said. White smoke billows from lighter fuels such as grass. And smoke can appear orange if nearby flames are bright and glowing.
Behind the hotshot crew were bulldozer and water crews ready to act if the fire jumped a bulldozed line at the head of the canyon that was to contain the fire to about 150 acres, fire information officer Mike Martin said.
About 565 firefighters and personnel were on the scene of the lightning-sparked Milford Flat fire, which is burning through Millard and Beaver counties.
E-mail: lhancock@desnews.com