A natural gas pipeline that was undergoing safety testing burst open Sunday afternoon, sending water, mud and rocks across northbound Interstate 280 at Farm Hill Boulevard.
The Chronicle reported it was the same line 132 that exploded in San Bruno last year and that is was the second problem on that line in the past four days. Line 132 runs from Milpitas to San Francisco. On Thursday a similar safety test using high pressure water lead to the discovery of a pinhole leak near the Palo Alto.
Sunday's test caused a rip much bigger than a pinhole. KTVU showed an image of the hole and it appeared several feet long and a foot wide.
"It was part of a hydro test on the line that was adjacent to part of the line where we had a pinnole leak" last week, PG&E spokesman David Eisenhauer told the Chronicle, adding the pipe that failed was 24 inches in diameter.
The burst line was first detected a little before 3:30 p.m. Sunday, when a driver contacted the Woodside Fire Department, saying that a large geyser of water was getting cars on both sides of the freeway wet, said Battalion Chief Kevin Butler.
Moments later, an explosion was reported in the same area, along with a large volume of flowing water. When firefighters arrived on the scene, they found a large amount of mud, rocks and debris from the hillside east of the freeway scattered across the northbound lanes.
There was also a faint smell of natural gas, Butler said. Butler said they learned that PG&E had been conducting hydrostatic testing of natural gas pipelines in the area, meaning that water is pumped through the lines to detect any weak points.
After the area tested safe for gas levels, fire crews searched the hillside next to the freeway and located a 5 foot by 5 foot crater caused by a ruptured gas line.
The crater was located in an easement running behind homes, and the closest house was about 100 yards away, Butler said.
The pipeline that burst had been emptied of gas before testing began. The mudslide initially shut down all of northbound Interstate 280.
The right lane remains closed while crews remove the remaining debris from the road, according to the California Highway Patrol. There were no injuries, but one vehicle was damaged by pieces of dirt and rock, Butler said. PG&E has not yet returned a call requesting further information.
Bay City News contributed to this report.