Juice: Blowin in the Dry Wind

28 Nov 2017

Four years ago, San Diego Gas & Electric power lines sparked wildfires that burned some 200,000 acres in San Diego County. The fires, which began in the eastern area of the county, were quickly blown westward by severe Santa Ana winds. They wound up destroying 2,500 homes and structures as they burned through the dry chaparral landscape. By the time they were extinguished, seven people had died and almost a half million people had to be evacuated.

Power lines, according to Bill Stewart, co-director of the University of California at Berkeley’s Center for Fire Research & Outreach, historically have ignited some of the biggest fires known in the state. However, they do so only when winds whip up and cause lines to arc, fall to the ground, or come into contact with combustible material.

The California Public Utilities Commission has extensive rules aimed at preventing the vast system of poles and wires that transmit and distribute power from igniting fires. Generally, they require utilities to clear vegetation around power lines, insure the integrity of the poles, and make sure that lines (including communications lines) are not placed so closely together that they can contact one another when winds whip up or stress poles.

It’s time for state officials and lawmakers to emphasize how land use comes into play as a threat to life and property just as much as they are emphasizing how power lines are a factor. Efforts to make power lines safer may eliminate some large wildfires in the future, but not stop them.

The task of following and enforcing the rules has been daunting given the sheer size of the state’s power grid. There are 33,000 miles of lines. On top of that, a map recently completed by state agencies shows that 47.2 percent of California’s land mass, or 74,756 square miles, has an elevated fire risk. The map further shows that some 5.5 percent, or 8,799 square miles, has an “extreme” risk of fire.

In light of the danger, the CPUC is now doubling down on its fire safety rules for electric utilities with a proposal to require wider vegetation clearances, more frequent inspections to verify the integrity of electric lines, and development of fire risk prevention plans by utilities, among other steps.

The cost of the regulatory proposal is virtually unknown, but it comes after the state’s utilities already have upped their efforts to prevent wildfires and suffered huge costs and rising insurance rates due to their role in past fires. Southern California Edison, for instance, says its insurance rates have increased 10-fold due to utility-related fires in recent years.

In response to the increased focus on utility-sparked wildfires, Pacific Gas & Electric, for instance, has been surveilling wide expanses of land with helicopters to quickly detect wildfires.

San Diego Gas & Electric has placed a series of cameras in the back country to spot wildfires when they first ignite. The San Diego utility also has  some 170 weather stations to monitor winds.

When they become threatening, the utility sends in contract fire-fighting crews and utility workers to quickly get an upper hand on any fire that may start, according to Allison Torres, utility spokesperson. It also activates a communications system that messages people in the windy areas to take precautions and to ultimately notify them that if the risk becomes too high the utility will turn off power in their area.

The utility has changed its switches too so that when winds cause lines to arc, for instance, they can be opened to stop power from flowing for as long as needed in the area. One of the causes of the 2007 fire in San Diego was that the switches automatically closed and allowed power to flow again after lines arced if they didn’t quickly arc again.

So far power shutoffs to prevent wildfires in high wind conditions in San Diego County have been minimal, according to Torres, with only about 1,000 people affected on the 16 occasions the utility has activated the power shutoff policy since 2013. However, that may be because the weather has lately been kind in the county.

SDG&E meteorologists backcasted the impact of the power shutoff policy and found that between 2002 and 2008 high winds would have required it so turn off power 14 times in various areas. The outages would have varied in their scope, with the most geographically widespread one affecting almost 50,000 people for 13 hours and the longest, though affecting just about 6,000 people, lasting 49 hours.

So far, the utility has been the only one to shut off power when winds become threatening. It is a strategy that raises the hackles of the public due to inconvenience. Some say too that it raises the danger of fire from other risks. Critics point out that when power is out, residents may resort to cooking on backyard grills or propane stoves, which is dangerous in high wind conditions.

One thing is certain, though. Once the CPUC adopts its new rules requiring utilities to develop fire prevention plans the state’s other major utilities will be looking closely at what SDG&E has done.

While the particulars of population distribution, topography, vegetation, and weather vary greatly in California simply shutting down power in areas where winds become dangerously high may be an effective strategy in preventing some wildfires.

Then again, once winds whip up any potential source of ignition can cause huge uncontrollable blazes. Ironically, the 2007 wildfire sparked by SDG&E lines in San Diego County burned over much of the same brushy back country area that a fire in 2003 roared through after a lost hunter in the Cuyamaca Mountains set a campfire to send up smoke so rescuers could locate him. That blaze, known as the Cedar Fire, killed 15 people and burned down about 2,800 structures as Santa Ana winds blew it across 280,000 acres of the county.

Homes were rebuilt, some only to burn again in the 2007 fire.

This raises the question of why local agencies allow development at all in fire prone areas and why rebuilding continues, just like rebuilding is allowed multiple times on barrier islands that are regularly swept by hurricanes and coastal storm surges.

California and the West have had wildfires for eons and they play a major role in shaping and renewing the ecosystem. Despite the best efforts of state regulators and utilities, they will to continue to occur when dry winds blow.

—William J. Kelly

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