As you may recall, last week Bernalwood introduced you to Line 109, a PG&E gas pipeline that has recently become the focus of much concern, in light of potential safety issues that could cause the line to explode in a searing fireball — much as it did here once before, in 1963.
Bernalwood has since been in contact with Paul Parmley, a representative from PG&E, who offered to answer any questions we have about Line 109 in Bernal Heights. And indeed, we had some questions. So here they are, along with the answers we received from Mr. Parmley.
Q. What detail can you provide about the section of Line 109 that runs through Bernal Heights?
Line 109 through the Bernal Heights neighborhood is 26-inches in diameter. Line 109 has a maximum operating pressure of 145 psig. The current pipeline was installed in 1981 and 1982, and it was pressure tested during construction to 550 psig for eight hours. The pipeline operates at less than 19% of the specified minimum yield strength (SMYS) at this location, providing a considerable margin of safety.
Q. Have any sections of the line in Bernal been replaced in the last 50 years?
The section of Line 109 in the Bernal Heights neighborhood, between Alemany Blvd. and Cesar Chavez, was installed in 1981 and 1982.
Q. When was Line 109 last inspected, and how?
PG&E has a comprehensive inspection and monitoring program to ensure the safety of its natural gas transmission pipeline system. PG&E regularly conducts patrols, leak surveys, and cathodic protection (corrosion protection) system inspections for its natural gas pipelines. Any issues identified as a threat to public safety are immediately addressed.
Patrols: PG&E performs regular patrolling of transmission pipelines to look for indications of pipeline leaks, missing pipeline markers, construction activity and other factors that may threaten the pipeline. Line 109 through the Bernal Heights neighborhood was last patrolled in August 2011, and everything was found to be normal.
Leak Surveys: PG&E regularly conducts leak surveys of its natural gas transmission pipelines. After the San Bruno incident, PG&E performed additional ground leak surveys for its entire natural gas transmission system. Leak surveys are generally conducted with a leak surveyor walking above the pipeline using leak detection instruments. Line 109 was last leak surveyed in April 2011, and no leaks were found.
Cathodic Protection System Inspections: PG&E utilizes an active cathodic protection (CP) system on its gas transmission and distribution pipelines to protect them against corrosion. PG&E inspects its CP systems every two months to ensure they are operating correctly. The CP systems on Line 109 were last inspected in September 2011, and everything was found to be operating correctly.
Integrity Assessments: PG&E also performs integrity assessments of certain gas transmission pipelines in urban and suburban areas. Line 109 had an external corrosion direct assessment (“ECDA”) in 2009. This assessment identified no issues requiring corrective action.
Q. Have the records pertaining to the Bernal portion of 109 been validated?
PG&E pressure test records for Line 109 in the Bernal Heights neighborhood are complete.
So there you have it. The good news is, our section of Line 109 is relatively new, and thus hopefully does not have any of the shoddy, 1950s-era welds that were blamed in the San Bruno explosion. Likwise, it seems that an active inspection regimen is in place to validate the line’s integrity.
This is encouraging stuff, and we are grateful to PG&E for for providing such detailed information. Yet given the magnitude of PG&E’s recent mismanagement of its pipeline infrastructure, and the tremendous potential for harm, unwavering diligence will be required by both Bernal Heights residents and our local authorities to ensure the pipeline will remain safe for decades to come.
As Reader Tara commented earlier this week:
Thanks for asking for a summary and please post an update whether or not you receive a reply. This article about PG&E in SF Gate yesterday got me even more pissed off and scared about this. Trying to think about what we can do as influential citizens of Bernalwood.