SCOTTS VALLEY (CBS SF) -- While progress was being made against the massive CZU Lightning Complex early Friday, the firefight deep within the Santa Cruz Mountains remains intense with the blaze burning through several feet of dead material on the forest floor.
Firefighters called the thick matting 'duff' and it consists of a combustible mixture of freshly fallen twigs, needles, and leaves and immediately resting right above the mineral soil.
SCU Complex Operations Chief Mark Bruton said the thick 'duff' fueled an flareup of the fire near Ben Lomond-Brookdale area on Thursday.
"We ended up having a little setback yesterday," Bruton told reporters at the complex's Thursday morning briefing. "We had 30 acres of what's call a 'slop over.' It's a fire that crossed the (fire) line and a lot of that has to do to the fact again that there hasn't been a fire history here for such a long time."
Years of growth, drought and changing seasons has left the forest in several areas covered with knee-high duff.
"The matter that's on the forest floor is very thick, very thick material," Bruton said. "When we put our control lines in we scrap those lines down to the bare mineral soil...You really have to have those lines very deep, it almost becomes a trench at some point."
Burton said the 'duff' ignited Wednesday's flareup.
"In this case what we believe happened is that the fire was able to creep slowly within that (the duff) and pop up on the other side of our lines," he said.
The 'duff' is presenting firefighters with yet another challenge as they wrestle for control of the complex that had grown to 82,540 acres by Friday morning with 26 percent containment. At least 554 homes have been destroyed.
"In an area that has been a challenge because of the topography and the fuels and with all the homes -- there is yet another challenge," Bruton said.
Firefighters also faced a new challenge away from the fire.
A crew doing mop-up work and extinguishing spot fires near the Boulder Creek County Club made a stunning discovery Thursday night -- an abandoned toolbox containing an apparent pipe bomb and other explosives.
At a Friday morning news conference, Santa Cruz County Deputy Sheriff Chris Clark said a bomb squad had safely detonated the device and explosives.
"At this point, we are investigating," Clark said. "You hear about a pipe bomb, you hear about explosive devices. It's concerning to the people who live up there."
The incident began Thursday afternoon as the crews were working in neighborhoods forced to evacuate in advance of the massive fire.
"It started with firefighters doing mop-up work and putting out spot fire in the Boulder Creek Country Club area (in the 100 block of Lake Drive)," Clark said. "In doing that, they ended up noticing a toolbox that was open. They looked down and found what appeared to be a pipe bomb."
Sensing immediate danger, the firefighters backed away to a safe distance and called the sheriff's department. Arriving deputies quickly called in the bomb squad.
Clark said he has examined photos of the device.
"By the pictures I looked at that's exactly what it appeared to be (a pipe bomb)," he said. "That's exactly the impression I would have gotten had I looked down and seen it."
Meanwhile, most San Mateo County evacuees were allowed to begin returning home on Thursday for coastal communities affected by the complex fire.
Evacuation orders and repopulation began in areas of Bean Hollow State Beach, Pescadero Beach, Pescadero Creek County Park, Pescadero, San Gregorio, La Honda, Langley Hill and Red Barn, Russian Ridge Open Space, Skylonda, Portola Redwoods State Park, Portola Heights and Middleton Tract.
Before returning, residents should check San Mateo County's Wildfire Recovery repopulation map to determine if their home is accessible.
CZU LIGHTNING COMPLEX FIRES
- Evacuation Info, Burn Zone Map, Fast Facts
- Evacuation Map
- Google Map of Fire Area
- Wildfire Shelter Map, Information
Roadblocks were also lifted at state Highway 1 at Gazos Creek Road, Cloverdale Road at Butano Cutoff, Pescadero Creek Road at Butano Cutoff and Pescadero Creek Road at Burns Valley Road.
Cal Fire urged residents to exercise caution when returning as emergency vehicles continue to operate in the area. Non-residents should stay away.
People can visit San Mateo County's news release for additional resources and information.
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