PG&E's plans to repair or replace large sections of the nearly 12 miles of main gas lines in Palo Alto may end up taking years to complete, a top engineer told an inquisitive City Council Monday night.
That timeline was too long to satisfy Council Member Pat Burt, who with the rest of the council listened to hours of testimony from Todd Hogenson, director of PG&E’s Pipeline Safety Enhancement Plan (PSEP).
Hogenson gave a detailed account of the location, material composition, operating pressure, testing, and history of each of the three gas pipelines that run through Palo Alto, L-101, L-109, and the infamous L-132—the line that exploded in San Bruno last year, killing eight people.
An NTSB investigation found that explosion to be .
The PSEP was developed in the aftermath of that disaster and was submitted in August to the California Public Utilities Commission, which required all state gas utilities to draft such a plan.
Hogenson said that PG&E maintains 5,800 miles of pipelines in California, many of which were fabricated in the 1920’s and 30’s, long before the existence of modern pressure-testing tools. The first regulations on gas pipelines, he said, weren’t even drafted by the CPUC until 1961.
“Any pipelines installed before these dates were not required to be tested. They were grandfathered in,” he said. “We basically need to test all pipelines that have never been tested.”
The company plans to strength-test 165 miles of pipeline this year statewide, ramping up to 200 miles per year for the next four years.
PG&E designed a “decision tree” to prioritize which pipelines to inspect and repair or replace first.
The three lines in Palo Alto came up as a top priority given their proximity to dense population centers.
L-109, which is 4.64 miles long and was installed between 1936 and 2004, will have the entire portion that was laid in 1936—1.5 miles—replaced. That project is expected to take until 2014, which raised red flags for Pat Burt.
“Going into this session I was more concerned with Line 132,” said Burt, “and now I’m more focused on the segment of line 109 that basically runs between Middlefield Road and Alma Street.”
Burt pointed out that L-109 was of high enough concern to PG&E that they felt the need to replace it, but apparently not of enough concern to perform any hydrostatic tests in the mean time.
“What would it take to get hydro testing before 2013 on that line?” said Burt, who noted that Hogenson had just detailed four risk factors on L-109, including it’s old age, lack of prior pressure testing records, proximity to schools, and the fact that the seam running the length of the pipe is a “single-weld”.
PG&E’s policy, said Hogenson, is to not test lines that are being replaced.
“Is that really an adequate approach,” countered Burt, “if that’s our highest risk segment in the city?”
Hogenson admitted that the decision really came down to money.
“Right now we are spending more than $1.2 million for each mile to hydrotest,” he said, then packpedaled slightly, saying, “We think the pipeline is running safely. How is that pipeline gonna fail? What’s gonna cause that pipeline to fail? We’ve reduced the operating pressure in that pipeline.”
PG&E has, in fact, reduced the pressure. L-109, a 20 to 24-inch pipe rated to 375 psig, had its operating pressure reduced 20 percent after the San Bruno explosion, along with both other main lines in Palo Alto.
Burt remained unconvinced.
“If it wasn’t at the risk level that you would consider replacing it, it would therefore not be at risk of failing,” said Burt. “You have lower pressure, and that certainly is a major factor, but it can fail. You can have a corrosion spot just like you did on 132. You and I both know that if you’ve got corrosion that turned up in one place, that’s a yellow flag that there could be corrosion in another place.”
Hogenson nodded and scribbled some notes onto his pad at the podium.
In addition to the pipes, PG&E also plans to replace old manual valves with automated valves that can be either controlled remotely from PG&E’s control center in San Francisco, or set to automatically shut off in the event of a dangerous pressure change.
These types valves are being installed on all three lines at points in Mountain View and near Sand Hill Road in Menlo Park.
Council Member Greg Scharff asked Hogenson what the effect of lower pressure is on the system as a whole.
Hogenson said that he is concerned that the lower operating pressure may lead to curtailments, especially if there are severe cold days this winter.
“We’ve never had curtailments in the San Francisco Peninsula for decades,” said Hogenson, adding that PG&E has warned “non-core rate customers” such as hospitals that they might have their gas service curtailed if indeed it gets too cold.
In the meantime, PG&E will continue to work with city staff and the CPUC to complete testing, repair and replacement of high-priority gas line throughout Palo Alto.