Creating Defensible Space Around Utility Poles

Above: The power pole hazard mitigation crew’s sawyer flush cuts a palo verde stump.

By Tom Story

“As Arizona’s largest utility, there are fire risks we have to manage,” said Wade Ward, Fire Mitigation Specialist for Arizona Public Service (APS). “The primary goal of fire mitigation is to prevent fire from ever happening. The second is to provide safe and reliable electricity to the communities APS serves.  Just as important is the ability to provide for firefighter safety around our system in the event of a fire”, Mr. Ward continued.  “With five thousand miles of transmission and twenty-eight thousand miles of distribution it is hard not to have our system affected by wildland fire.  When this happens, APS’s priority is providing a safe environment for crews to work in”.

defensible space power poles
In Cave Creek, AZ; Wade Ward, Fire Mitigation Specialist for Arizona Public Service, sizes up a palo verde tree slated for removal as part of the APS Defensible Space Around Poles program.

Mr. Ward knows fire (he joined APS after his fire career at the Prescott Fire Department) and he has seen factors like drought, climate change and forest management set the stage for larger and more powerful wildland fires.  “It is becoming more evident that due to extended drought over the past decade forest and vegetation ecosystems have been stressed from the lack of regular moisture compounded by shorter drier winters and longer warmer summers,” Mr. Ward said.

APS sends out inspectors to identify hazardous vegetation in violation of its safety and reliability clearance standards as well as violations of the National Fire Code and the Urban Wildland Interface Code (which state that a utility with equipment attached to the pole must clear all vegetation 10 feet in all directions including 10 feet from the ground). The area around the pole is cleared by work crews to create defensible space.  “There are approximately 70 thousand poles within our system that we will have on a three year return cycle to maintain Defensible Space Around Poles (DSAP)” said Mr. Ward.

defensible space power poles
Other crew members cut up and feed the branches into a chipper.

The clearing is being done using manual methods (including chain saws, string trimmers and other hand tools) and where approved is followed by the application of herbicide in compliance with Environmental Protection Agency’s Integrated Vegetation Management practices. APS has prioritized the treatment of subject poles by utilizing data derived from a risk assessment done across the state. Mr. Ward continued; “It is a part of our core values at APS Forestry to manage vegetation and the environment by balancing benefits to create healthy forests and safe reliable energy”.

Mr. Ward finished his remarks noting, “In 2016 we created 110 acres of defensible space around the state of Arizona. One pole at a time”.

defensible space power poles
Putting the finishing touches on the cleanup around one of the Arizona Public Service power poles in Cave Creek, AZ.

Researchers recommend amount of fire clearance around structures

Researchers have concluded that the most effective fire clearance or defensible space around structures, to reduce the chances of them burning in a wildfire, is between 16 and 58 feet.

Below is an excerpt from the abstract of a paper written by Alexandra D. Syphard, Teresa J. Brennan, and Jon E. Keeley, submitted to a journal September 16, 2014.

We analysed the role of defensible space by mapping and measuring a suite of variables on modern pre-fire aerial photography for 1000 destroyed and 1000 surviving structures for all fires where homes burned from 2001 to 2010 in San Diego County, CA, USA. Structures were more likely to survive a fire with defensible space immediately adjacent to them. The most effective treatment distance varied between 5 and 20 m (16–58 ft) from the structure, but distances larger than 30 m (100 ft) did not provide additional protection, even for structures located on steep slopes.

Two of the three authors are public employees, so the taxpayers already paid for this research. However, if you want a copy of The role of defensible space for residential structure protection during wildfires, it will cost you $25.

More about Open Access to research that is paid for by taxpayers.


CalFire bills for fire prevention

California homeowners will soon receive bills in the mail for fire protection. Beginning next week, bills for as much as $150 will be sent; most homeowners’ bills will run $115, with a $35 discount for people who live in fire protection districts and already pay for fire services.

The annual fee is controversial; it was signed into law last year to provide funding for CalFire and has been heavily criticized by rural residents who view it as “double taxation.” Taxpayer advocate groups, according to the Union Democrat, argue that the fee is a tax and should have required a two-thirds vote by the Legislature instead of just a simple majority vote.

Houses and other structures in the 31-million-acre State Responsibility Area (SRA) will be billed at the $150 rate. Daniel Berlant with CalFire told KPBS news that the number of structures in the SRA has grown by about 16 percent in the last decade. “That’s where the residential area starts meeting up into the forest,” said Berlant. “It’s that middle section that we call the wildland-urban interface where we see the most fires that cause impact and damage throughout California,so the rural residents that the state is responsible for protecting are the ones that will be assessed the fee.”

CalFire home safety site

The annual fee is $150 for the first structure and $25 for each additional structure on the property. The Rancho Santa Fe Review reported that the funds pay for prevention activities on SRA lands.

CalFire has a parcel viewer online to view mapped SRA lands.

Property owners who disagree with the fire fee assessed on their properties can petition for a redetermination of the fee calculation. The petition must be based on whether the fee applies to the property for which the petition is filed, and must detail the grounds for redetermination of the fee. Grounds could include proof of whether the structure is actually located in the SRA or the number of habitable structures or pre-existing local fire protection services. The website has more details.