The company says it doesn't wait to do repairs if public safety is at risk and a dented pipe is getting repaired without going on the top 100 list, but it took a while.
The pipeline was inspected in July, but the results weren't known until a week ago.
Crews have started what will be a multi-day project to replace a section of high-pressure gas transmission pipe -- a pipe dating back to 1951 and that's long before the nearby houses were built.
"The results we got back showed the appearance of what could be a dent in this line at this location, a small dent, so it's an example how we're not putting it on the planning list -- a long-term planning list. We're going to take immediate action to make the repair and get things back to normal again," PG&E Spokesman Brian Swanson said.
PG&E used a sophisticated device called a 'pig.' It has sensors to detect welds, corrosion, dents and other imperfections.
Buried 59 years ago, this pipe and others like it raise questions about how well it was made and by whom.
"Steel came from England and Germany, and one of the questions we may address is, was the quality of the steel which has been used in 1956 comparable to the kind of quality of steel we're using nowadays?" USC Chair of Civil Engineering Jean Pierre Bardet said.
That's not an easy question to answer.
"It is a major concern, but I want to withhold any opinion as to whether we need to rip open hundreds of miles of transmission lines to replace them until the NTSB comes back with their report," Rep. Jackie Speier, D-San Mateo, said.
The dented pipe in San Jose is wrapped with a coating to prevent corrosion.
In the meantime, PG&E is also busy meeting with mayors and other officials about the pipes on its top 100 list. The one in San Carlos is 105 feet long and 24 inches in diameter.
"We're very interested, of course, in more specifics in San Carlos. What is the situation and what are we going to do about it and when," San Carlos Mayor Randy Royce said.
The dent was fairly easy for PG&E to identify because the pipeline is straight.
The top 100 ranking is a weighted list based on four criteria:
- The potential for third party damage, such as an accident by a contractor doing work in the area
- Potential for corrosion
- Ground movement, such as an earthquake
- Physical design and characteristics, such as age of the pipe
The segments can be mere feet or yards long.
"Now a segment could be an area of pipe between two valves, segment could be where the type of type is different where it transitions into another type, they could be as short as two-foot segments or mile-long segments," Johns said.
The list is raising awareness of pipeline safety all over central and northern California.
At another top-ranked site on the border of San Jose and Milpitas, shoppers at a mall expressed concern.
"I am concerned, I knew it was in Milpitas but I didn't know it was here," San Jose resident Suresh Rajan said.
PG&E said if a pipe poses an imminent safety risk, repairs are made immediately. It is still assessing whether segments of this pipeline need to be repaired or replaced.
PG&E customers can call 1-888-743-7431 for information about gas pipelines in their area.