The California Public Utilities Commission on Aug. 27 announced an investigation of the safety culture and security of the Pacific Gas & Electric Co. The announcement comes on the heels of a $1.6-billion fine. Both the probe and the fine are regulatory results of a gas leak explosion in 2010 that killed eight people in San Bruno, Calif., and an April, 2015 pipeline explosion that killed one person and injured 12 in Fresno, Calif. The utility says a new detection system it recently rolled out makes it better equipped to handle leaks than ever before.
After the San Bruno blast, the utility began tests of a gas-detection technology called Picarro Surveyor by Picarro Inc., Santa Clara, Calif. that is 1,000 times more sensitive than handheld methods, says Steve Redding, director of leak management in PG&E’s Gas Operations. The company began testing the technology and Redding says it found three times as many leaks than traditional methods. But CPUC wants to find out how it’s working first hand.
“We need to get at the root of the problem and determine why PG&E keeps having safety related issues,” said Michael Picker, CPUC president, in an August 27, statement.
The Picarro Surveyor uses Cavity Ring-Down Spectroscopy (CRDS) technology to detect and measure methane. CRDS is a process where a laser is bounced between two highly reflective mirrors and any material in between the mirrors—like traces of methane gas—will slow down the laser, allowing operators to identify the methane or whatever gas passes through the mirrors. The information feeds into Picarro’s web-based software that displays it as surveying data.
“I began working with a few of the scientists at Picarro and we were able to detect a 0.45 cu-ft an hour leak from three football fields away,” says Redding. To give an idea how small of a leak that is Redding says during a soap test—when workers cover a possibly leaking pipe with soap suds and look for bubbles to form from the release of gas—a leak that small doesn’t bubble up, it only foams.
In device tests, PG&E surveyors surveyed assets with tried methods. They use hand-held survey instruments that pick up a leak when it’s within 3-ft diameter around the surveyor, says Redding. A truck mounted with Picarro’s Survey system followed the surveyors. “Picarro came behind and found 80% more leaks,” says Redding, who adds that the PG&E surveyors are professionals, “some of the best in the world,” he says but even so, some of the leaks they missed and Picarro caught were what he calls dangerous leaks.
With the upgrade in detection power, the biggest challenge for PG&E is once it finds new leaks, legally it must respond to them in a specified amount of time. PG&E has four grades it assigns to leaks: one being the worst, requiring an immediate response and grade four being the least dangerous, needing to be checked every year, says Redding.
It’s these sorts of leak labels and response times that PUC will be scrutinizing in its wide probe into PG&E’s safety culture. “Now I can survey in one hour with the technology, what a foot surveyor could do in 40 hours,” says Redding. The CPUC investigation will decide if the tech upgrade is enough to stave off further state action.
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