PG&E has told regulators that more than 500,000 of its aging wood power poles are at potential risk of failing from hidden dry rot — including some 200,000 in high fire-threat areas, NBC Bay Area’s Investigative Unit has learned.
The company said it discovered the new “safety concern” during its investigation into why a wooden pole fell in a Danville backyard on July 8 of last year.
Bob Chace says he had just come in from his backyard that day and three minutes later he heard a crashing sound on his neighbor’s roof.
There was no fire and no one was injured, but Chace saw the downed line had ended up in his swimming pool. Fortunately, he said, the incident was in the middle of the day on a Wednesday so the pool was empty.
“Honestly, you don’t expect something like that to happen,” Chace said. “It was pretty traumatic.”
While Chace said he had noticed the pole was leaning about four feet around a week before, he didn’t think that was unusual for such an old pole.
PG&E’s investigation of the incident, which has not been made public, concluded the pole fell because of long undetected dry rot at its base, the company told regulators in a notice filed last month. That notice acknowledged a larger risk exists for 543,560 of its poles that had been installed more than three decades ago.
“That’s a lot of poles,” said former CPUC Commissioner Catherine Sandoval, who specialized in pole safety during her six-year tenure on the panel. “This is a massive safety problem.”
The poles all date to before 1989. That’s when PG&E stopped using a pesticide-laced gas process known as Cellon treatment to preserve them. The company switched away from the Cellon process when more environmentally friendly methods became available.
But there was another problem -- PG&E field engineers warned back in 2007 that the more than half million Cellon-treated poles wouldn’t last more than a decade. The treatment has proven ineffective in some cases and was known to wear off over time.
But the company did not replace the aging poles, relying instead on regular inspections to assure their safety.
“To reduce safety and reliability risks related to Cellon-treated poles, PG&E routinely inspects its wooden poles, including Cellon-treated poles, for internal dry rot to ensure the poles are safe,’’ the company said in a statement to NBC Bay Area.
But in its notice to regulators, PG&E acknowledged those routine inspections of the Danville pole had missed the rot over the course of two decades. The pole had been inspected in 2005 and again in 2015, the company says.
“The standard intrusive inspection method we use to inspect Cellon-treated wood poles may, in some cases, result in readings that do not accurately reflect the internal health of these poles,” the company told regulators.
PG&E’s review determined that its practice of reusing existing holes in poles to look for rot and inject fumigant was part of the problem. To avoid weakening the aging poles, the company directed its crews to reuse existing holes in checking for rot, rather than drill new test holes. But the utility now says the fumigant only penetrated the immediate area around the old holes, and that “led to a misunderstanding” of pole integrity and “hindered the detection of internal dry rot.”
“Overall, the aging population of our Cellon-treated poles combined with the potential that current probe testing methods do not detect actual internal wood conditions raises a safety concern, particularly for the poles located in populated areas,” the company concluded in its notice to regulators.
“This risk is exacerbated by the quantity of older poles in our system and the increasing need to replace or reinforce these poles as they age.’’
The company says it will now require crews to bore new holes on poles to inspect them, instead of using existing holes.
The median age of its Cellon-treated poles is now 44, the company says, and it acknowledged the risk of sudden failure becomes most pronounced at 42 years in service. Nearly three quarters of the company’s Cellon-treated poles are more than four decades old, the company says, and all of them will be at-risk by 2030.
State regulators say more than 200,000 of the Cellon treated poles are in high fire-risk areas.
PG&E says it is developing a standard to prioritize which poles need to be replaced or reinforced, but Sandoval says stockholders, not ratepayers, should pay to fix the problem.
“They keep running past failure,” Sandoval said. “In the case of what happened in Danville, PG&E is just lucky that they didn’t kill anybody.”
Chace says PG&E officials told him the fallen line would have only been live for a split second, but he figures that would have been long enough to do some serious damage had anyone been in his pool.
“It’s kind of scary,” he said. “You know we’re fortunate that nothing like that happened.”