The Palo Alto foothills may be a choice haven for local hikers and birdwatchers, but for the city's utility officials, the verdant open space preserves west of Interstate Highway 280 also represents a potentially catastrophic fire danger.
The land west of the highway was designated last year at "elevated risk" area for wildfire, thanks in large part to the existence of electric power lines and utility equipment. This places the foothills area in "Tier 2" of the three-tiered system established by the California Public Utilities Code, with Tier 3 connoting "extreme danger." (Any area not in Tiers 2 or 3 is considered Tier 1, or "moderate risk.")
In August 2018, the City Council officially declared the foothills area to be "at significant risk of catastrophic wildfire," a designation that prompted utilities department staff to plan new measures to reduce the threat. Now, Palo Alto Utilities is in the midst of putting together the Utilities Wildfire Mitigation Plan, a document that the city needs to adopt to comply with Senate Bill 901.
The bill, which was signed by Gov. Jerry Brown in September 2018 in response to devastating wildfires, requires utilities to develop wildfire management plans that focus on power lines and other utility equipment.
In Palo Alto, about two-thirds of the power lines in the foothills area are positioned on overhead lines, which typically rely on wooden poles. The rest are located underground, according to Tom Ting, electric engineering manager at the utilities department. As part of the new plan, staff is evaluating its practices for undergrounding electric equipment and exploring a possible switch from wooden poles to ones made of composite metal or steel, Ting said.
To date, the city has no reported incidents of wildfires being caused by electrical equipment, Ting told the Utilities Advisory Commission on Wednesday.
"It means that what we've done in the past in mitigation management has helped. But it doesn't mean it will work going forward," Ting said.
Ting pointed to a list of factors that make wildfires increasingly prevalent in California, including higher temperatures, a higher density of vegetation and the recent drought period, which has made conditions drier.
"I don't think it's going to get better. It's going to get, if anything, worse," Ting said.
A key component of the plan is managing the vegetation in the foothills area. The city's Urban Forestry division has been evaluating every tree within the high-risk area to determine which have the potential to fall into an overhead line or have a branch strike a line. These trees then undergo more frequent and detailed inspections.
Ting said the utilities department has also increased its inspection intervals for electric equipment in the high-risk area. In the past, the equipment was inspected every three years; now inspections occur every year. And if inspections identify maintenance requirements in the foothills area, the department has to address them more quickly than it would elsewhere.
While the new plan focuses specifically on utilities, other City Hall departments have already been working on other measures to prepare for potential wildfires. In 2016, the city updated its Foothills Fire Management Plan, a broad document that was initially adopted in 2009.
The 2016 plan, which was crafted by the consultant Wildland Resource Management in collaboration with the Fire Department, Public Works, Community Services and Office of Emergency Services, identified new vegetation areas that should be treated. This includes the creation of "ignition prevention" spaces around barbecues within the parks and the widening of evacuation routes from open space preserves. Other significant actions that the city had undertaken include prescribed fires and mowing vegetation near residential boundaries.
The most important benefit, the Foothills Fire Management Plan states, "has been an increased ease of evacuation and emergency access through the expansion of managed roadside vegetation."
"The roadsides along Arastradero Road, Los Trancos Road and Page Mill Road are all safer for access and egress through increased line of sight, reduced fuel volumes and reduction of ladder fuels," the plan states. "The probability of ignitions has been reduced through a reduction of fuels near barbeques and structures, and along roadsides."
Utilities staff plans to bring the new utilities plan to the council for approval in December.