LOS ANGELES – When the firestorms of October were finally extinguished and hundreds of thousands of Southern Californians returned to their homes, officials set out to understand how 21 fires erupted in the span of just three days.
Searching high and low, they found the easiest explanations at ground level: A 10-year-old boy confessed to starting one fire while playing with matches. That blaze blackened 38,000 acres north of Los Angeles, though authorities opted not to press charges against the youth, described as distraught.
Two other fires were attributed to arson, something officials said happens routinely when wildfires erupt elsewhere. “The arsonists jump in because they have cover; there’s other fires already,” said Bill Peters, spokesman for the California Department of Forestry and Fire Protection.
In fact, the leading cause of ignition appeared to be power lines.
As many as eight fires were blamed on sparks from lines blown down by the high, hot Santa Ana winds that sweep across Southern California each autumn. The Witch fire, which burned 200,000 acres and killed two people, was ignited by a power line, as was the smaller Guejito blaze, with which it merged.
The findings have renewed calls for improving the safety of the lines, either by reinforcing poles and line fasteners or, in some cases, placing cables underground in rural areas that see the worst winds.
“We’re certainly all looking at undergrounding in fire-prone rural areas – even though that hasn’t been the norm – given the number of fires that have broken out over the last several years,” said Christy Heiser, a spokeswoman for San Diego Gas and Electric. She noted that 60 percent of the utility’s lines already are underground, twice the national average.
The problem is expense. Burying power lines can cost $1 million a mile. It also makes any repair a matter of digging.
“People don’t understand the consequences of it,” said Jim Kelly, vice president for engineering and technical services at Southern California Edison, which is less eager to underground. “It’s like using a 20 pound sledge hammer to kill an ant.”
Edison is experimenting with less costly options, including poles made from composite materials designed to withstand winds that are “sufficient in some instances to snap wooden poles,” Kelly said.
Indeed the Santa Ana winds remain the primary reason for October’s fire. The gusty, dry gales exceeded 100 mph, and blew steadily for so long that they drove fires over terrain that had been thoroughly burned four years earlier.
“As a general rule, the younger the stand, the less fuel there is,” said Jon Keeley, an ecologist with the U.S. Geological Service. “But if you overlay what burned in October 2007 against earlier fire histories, what you can see is a huge portion of what burned in 2003 got re-burned. If you include the 2002 fires, it’s like 100,000 acres.”
Keeley said that suggests that controlled burns are relatively ineffective on southern California’s scrubby landscape. In testimony to a Senate panel last month, he urged restricting new residential development in fire-prone areas, tightening building codes on the houses that are built, and exploring burial of power lines in the corridors that Santa Ana winds sweep through.
“Power companies aren’t eager to do it because it’s expensive,” he said. “But given the cost of these fires I can’t believe it’s not cost effective.”