PG&E is gearing up for a third night of testing in San Jose's Berryessa District. The focus is a 3-mile section of natural gas pipeline that runs through a large subdivision, next to a park and along the route parents walk their kids to school.
PG&E sent letters and made phone calls to residents to let them know about the test.
"At least they're working on it, so I feel a little better," said Ramstree Lane resident Vinna Lam. "I've been living here almost seven years, and I know this pipe has been there, so if something happens, now they update the pipe there."
The test involves purging the 34-inch pipeline of natural gas, then filling it with water. The water is then pressurized while instruments monitor if there is sign of a leak. A drop in pressure would be a key clue.
"We would go isolate that down and then excavate and do a full analysis of the pipe," said PG&E spokesman Joe Molica. "We have new pipe ready to go so if there were any issues during the course of these tests that we're doing over about the two weeks that this test takes, we have new pipe ready to go."
PG&E is testing 152 miles of pipeline that is similar in age or characteristics as the San Bruno line that ruptured and exploded last year. Since testing began in early May, 35 miles of pipeline have been tested so far. PG&E has records of previous testing for another 39 miles. That leaves about 74 miles to go.
It will take four nights for engineers to complete the 12-mile section of San Jose pipeline. They're doing three miles at a time.
In some areas, PG&E has also used remote-controlled devices called pigs to do some of the testing, even shooting lasers shot from helicopters. PG&E says all tests have been successful and no pipelines have had to be replaced.