Despite your electric utility’s best efforts to maintain a safe and reliable system, Mother Nature often has the last word.
Strong winds snap trees like toothpicks. Heavy rains saturate the ground, weakening tree root systems. Ice and heavy snowfall weigh down and break branches. Sparks ignite vegetation and spread fire.
Regardless of the cause, when any part of a tree contacts a power line, the result is the same: loss of electrical service and compromised public safety.
Even before alleged poor maintenance of transmission lines by Pacific Gas & Electric caused deadly wildfires in California, community-owned utilities invested millions on inspections and tree trimming.
At $1.76 million a year, vegetation management is the largest single line item in the budget of Lane Electric Cooperative, based in Eugene, Oregon, says Tony Toncray, operations manager.
“In 2001, we realized we needed to look deeper into our tree program,” Toncray says. “We had not been clearing our rights-of-way, and it was causing problems. We added staff, and began a three-year rotational trimming schedule.
“We know some trees grow faster—cycle busters—so we drive our system every year looking for those. We now are gathering data about the species in each right-of-way and entering it into a database.”
A minimum of three and up to four contract crews work year-round in Lane’s territory.
Northern Lights Inc., based in Sagle, Idaho, annually spends about $2 million on trees, says Kristin Mettke, engineering and operations manager.
“We want to keep the lights on,” Mettke says. “If trees don’t get into the lines, we have less outages—and with less outages, we spend less on overtime for line crews. It’s buying an insurance policy, essentially.”
NLI has two year-round contract tree-trimming crews and a full-time tree foreman. From April through October, that balloons to five to six aerial crews and two to three ground crews that clean up debris or grind stumps.
Trees along the system’s 1,570 miles of overhead line are trimmed an average of every five to six years, although faster-growing areas are visited more often, and crews are redirected as new hazards are discovered.
“During a storm, people are more willing to have their trees trimmed,” Mettke says. “They want their power on.”
Pat Holley, assistant general manager at Lassen Municipal Utility District in Susanville, California, says LMUD inspects every distribution and transmission line in its system every year. The 1,900-square-mile district ranges from desert valleys to high alpine, and includes private as well as federal forests.
“Now we are inspecting at ground level, but we are gearing up to begin drone inspections this year,” Holley says. “We will be able to look down on structures to detect problems.”
One contract crew works year-round trimming trees. LMUD personnel each spend about a month a year doing inspections and related work. A 20-foot area is brushed clear of vegetation around the base of all poles with equipment mounted overhead in high fire danger zones every year so sparks have nothing to ignite.
As part of its state-mandated wildfire mitigation plan, LMUD plans to extend easement width clearing from 50 feet to 200 feet where possible to provide better protection from windstorms and serve as a fire break.
Distribution line rights-of-way typically are 20 feet—not enough to prevent things outside the right-of-way from causing problems, Toncray notes.
Wildfire is a serious concern. In 2018, the Whaleback Fire—suspected to have started from lightning—burned 18,703 acres, closed portions of Lassen National Park, forced evacuations and destroyed LMUD’s 125-pole Eagle Lake distribution line. A portable generator provided power to the area for months while the 6.5 miles of overhead line was replaced with 10 miles of underground wire.
Although PG&E was ruled responsible for wildfires because it failed to correct maintenance issues it had tagged, “nine of 10 wildfires are manmade or naturally occurring,” Holley notes.
As part of its mitigation plan, LMUD is expanding the capabilities of its computer monitoring and control system. Rather than automatically fixing a fault during fire season, a crew checks the line before it is re-energized.
Federated Rural Electric Insurance Exchange President and CEO Phil Irwin, who works with electric utilities on coverage, appreciates the investments.
The mutual insurance company buys reinsurance to mitigate its risk—and in the wake of PG&E’s proposed $24.5 billion settlement of all wildfire claims, reinsurers have little appetite to write policies for utilities, Irwin says.
When talking to reinsurers, Irwin says he emphasizes the difference between PG&E and publicly owned utilities, where staff live in the communities they serve and problems are much more personal.
Drought, more dead trees and an extended fire season mean trimming is not only the law, but it is the right thing to do, Toncray says.
“It’s important to keep public safety as our highest priority,” he says.
If you see a tree problem, please contact your utility. Most have a program to replace removed trees.
Prevent Problems: Plant the Right Tree in the Right Place
Trees beautify homes and property, and can lower utility bills if planted in the right spot. But care should be taken with trees near power lines. Outages are caused by trees or limbs falling on lines. Restoring power is expensive. So is trimming trees.
Before planting trees, bushes or shrubs, look up to see where overhead power lines may conflict with their growth. Remember: A 2-foot-tall fir seedling will grow more than 100 feet tall and 30 to 50 feet wide.
After you have looked up, look down. Planting over underground utilities can result in outages when tree or shrub roots grow into the lines, or in a potentially deadly shock if you dig into buried lines.
Your local nursery, garden center, electric utility or state forestry department can help you determine the appropriate tree for your situation. For information concerning tree selection and care, visit the National Arbor Day Foundation website at www.arborday.org.