A robotic camera inches along the inside of Line 132. Above ground human eyes scan the screen for signs of trouble like an incomplete seam weld along the length of the pipe.
The National Transportation Safety Board has pinpointed the spot where the San Bruno rupture began -- a faulty seam weld.
"So we're also looking at the information inside the pipe like branding and who made the pipe and all this information is going to be used to validate the safety of the pipe and also verify the records we have on the pipe," PG&E spokesperson Brian Swanson said.
The pipeline has to be dug up and cut open to insert the camera. Unlike tests already done in Mountain View and Antioch, the pipe gets the camera inspection before high pressure water testing because it is so similar to the ruptured section. A faulty weld will likely be caught be the camera.
Line 132 was installed in 1948. No one has seen inside it since. After the San Bruno rupture, which killed eight people and destroyed 38 homes, PG&E discovered the pipe had multiple welded seams, when records showed it as seamless. Now 150 miles of pipe with incomplete records will be tested and/or replaced this year.
"There will be trackers following the robotic camera as it travels through the pipe; if there are things we want to take a closer look at later, they mark that location, we'll come back and excavate and take a look," Swanson said.
PG&E says whenever it excavates a pipe for any reason, samples are taken of the tar covering and soil around the pipe and saved for further testing. There will be seven excavation sites along the three miles.. A total of 20 miles will be camera inspected by year's end.