PG&E identifies 239 pipelines at risk of failure
July 1st, 2012
Nearly two years after the pipeline explosion that killed eight people and devastated a neighborhood in San Bruno, Pacific Gas and Electric Co. considers 239 of its natural-gas transmission lines to be at risk of a similar failure, according to a company assessment obtained by The Chronicle.
PG&E has identified more than 500 trouble spots on those lines, along sections ranging from a few feet in length to more than a mile, spanning a combined 48 miles. The stretches have pipe-seam welds susceptible to failing because they are old, or because PG&E pressurized the pipes beyond legal limits without testing them afterward for possible problems.
The pipes include two gas lines running along the Peninsula, Lines 101 and 109, and Line 108 in the East Bay between Sunol and Livermore. They also include extensions of Line 132, the pipe that exploded in San Bruno on Sept. 9, 2010.
PG&E's planned solution is to replace some lines and test others with high-pressure water. The state ordered PG&E to conduct such inspections for some lines after the San Bruno disaster, and last year the company checked more than 160 miles of pipe.
But PG&E also says some of the over-pressurized lines won't need to be tested or replaced - a position that critics call a violation of federal law.
PG&E reached its conclusions after commissioning a study of its 1,000-mile network of gas transmission lines in urban areas. Engineers with the utility and its consulting company, Kiefner & Associates Inc., reviewed inspection histories and pipeline records, although PG&E is missing at least some documents for virtually all of its urban system.
Roland Trevino, PG&E vice president in charge of public safety and pipeline integrity management, said the company and Kiefner had determined which pipelines were at risk partly by looking at whether their pressure had ever exceeded the allowable level under federal law, either accidentally or during an intentional increase.
"This really is what the integrity rules were intended to do, to identify threats to the pipeline assets and, once those threats are identified," to fix them, Trevino said.
The PG&E study found that parts of Line 132, the pipe where a faulty weld ruptured in the San Bruno explosion, are at risk of a similarly disastrous failure. PG&E has taken about 2 miles of the line around the disaster site out of service, but the rest of the 51-mile pipe running from Milpitas to San Francisco is still carrying gas.
The sections at risk include at least three spots where a Chronicle analysis determined that PG&E regularly elevated gas pressures to illegal levels before the blast - extensions off the main line just north of the blast site and near its southern terminus in Milpitas.
PG&E will either hydro-test or replace the at-risk segments, according to company officials.
On Line 109, which also extends from Milpitas to San Francisco, the study found more than 80 at-risk sections totaling a combined length of more than 10 miles. PG&E plans to hydro-test or replace portions of the line this year.
Another Peninsula pipe, Line 101, has eight segments that could be prone to a disastrous failure, as does Line 108 from Sunol to Livermore, the PG&E assessment says. The company plans either to replace or test problem areas on those lines by next year.
Hillsborough Mayor Tom Kasten, whose city is bisected by both Lines 109 and 132, was disturbed by the company's findings. He said he has met repeatedly with PG&E to ask that it relocate transmission pipes that in some cases run through residents' yards.
"They have a history of either not knowing or not caring about their system," Kasten said. "They have a history of either not knowing or not caring about their system," Kasten said. "They have to demonstrate to everybody now that they knew they were wrong in the past and did not place a high priority on the integrity of these lines, and they have to focus on re-establishing that trust."
The company says it plans to hydro-test or replace 48 miles of pipe that its study identified as being at risk. That represented one-fifth of the 235 miles Kiefner & Associates assessed. The consultants ruled out seam failure danger on 62 miles of pipe that had been over-pressurized, finding that the lines were probably strong enough to withstand the surges.
Critics, however, say that under federal law, PG&E is obligated to hydro-test all pipes that have been over-pressurized.
"PG&E is clearly misinterpreting the regulations, which are fairly clear," said Richard Kuprewicz, a pipeline safety expert. "You have to inspect all the lines that qualify. You can't pick and choose" among them.
"They have shown in the past that they can't get this process right," said Kuprewicz, a consultant for the ratepayer group The Utility Reform Network. "They are in danger of repeating the same sins of the past. They haven't learned from their past mistakes, apparently."
But Kuprewicz said he is glad the company has admitted that at least some of its system is at risk.
"That's a step in the right direction, a sign that they are trying to get control of their operations," he said.
Ken Kraska, a metallurgical expert who has worked for utilities and now is a private consultant, said PG&E's problematic records give him little hope that the company can be relied on to decide which lines are at risk, short of hydro tests.
Kraska noted that the company's engineers had ruled out any seam failure threat from the San Bruno line and in PG&E's entire transmission system before the 2010 blast, disregarding several warning signs and previous failures.
"If you don't have people who understand what should be done in the first place and do not have the proper knowledge and backing of upper management, then any steps are going to be generally inadequate," he said.