Campus update about PG&E discussions
Larry Gibbs, associate vice provost for environmental health and safety, and other members of the university administration have been meeting with officials from PG&E about the safety of natural gas pipelines in the Stanford area since a gas-line explosion occurred in San Bruno in September. Here is his update:
Since the San Bruno tragedy of last September, Stanford officials have been following the investigation and taking an active role by meeting periodically with Pacific Gas & Electric officials to make sure Stanford has accurate and up-to-date information about the status of the natural gas transmission pipelines adjacent to the campus along Page Mill Road and Junipero Serra Boulevard (JSB). We want to provide the campus community a summary of the information we have received to date.
Additionally, we want to assure the community that Stanford project management, utilities and facilities staff are closely following and coordinating with PG&E any project work that is being planned or will be done near the gas transmission pipelines to ensure that safe procedures will be followed. Upcoming Stanford or Santa Clara County projects that may be done in this area in the near future include installation of high-speed Google fiber-optic cable, installation of new gas pressure regulating stations, sewer-line rebuilding and the JSB traffic-calming project. All of these projects are being planned and coordinated among appropriate Stanford, Santa Clara County and PG&E representatives.
There are two PG&E gas transmission lines that run parallel to Junipero Serra Boulevard from Page Mill to Sand Hill Road. Line 109, a 22-inch-diameter line, is on the campus side of the road; Line 132, a 24-inch-diameter pipe, is on the foothill side of the road. Underground pipeline location is clearly marked by signs and stakes along the roadway, and the pipe is normally buried about four feet below the surface. The lines are in a Santa Clara County roadway easement adjacent to or through Stanford land.
In addition to having a portion of Line 132, which is the line involved in the San Bruno incident, Stanford was also concerned to see that segments of Line 109 were included in the PG&E Top 100 Segments Report, which was released to the public after the San Bruno incident. PG&E has indicated that this priority list is used as an engineering tool for prioritizing maintenance projects and was never meant to be an indicator of overall risk of any particular transmission line.
PG&E has informed us that Line 109 was originally installed along the roadway in 1936; Line 132 was originally installed in 1947. Both gas pipelines, which carry natural gas from Milpitas to San Francisco, have had various segment updates in numerous years since their original installation.
During Stanford discussions last fall with PG&E, officials said that the gas transmission lines were evaluated for internal corrosion in 2007 and that none was found. The Junipero Serra segment of Line 109, however, did have its corrosion protection system enhanced. Upon further evaluation in 2009, the enhanced corrosion protection was found to be working as planned, PG&E said. This was explained as the reason for some limited segments of Line 109 to be placed on the priority list for continued evaluation of the corrosion protection systems.
More recently, PG&E was ordered by the California Public Utilities Commission to produce construction and maintenance records of all high-pressure gas pipelines in high-consequence areas such as the JSB pipelines, by March 15, 2011. PG&E has not been able to find records for the entire pipeline system, which is thousands of miles in length. PG&E officials have informed Stanford that they have found no records for most of the transmission line segments along Junipero Serra. As a short-term risk mitigation step, PG&E has been ordered to reduce the maximum operating pressure in these pipelines, which has been done. Additionally, it has performed external inspections of the pipelines, which did not identify any issues.
The university has also asked PG&E to elaborate on new media reports that pipelines built before 1970 have unreliable welds. The utility's officials emphasized that a gas line with proper corrosion protection can safely transport gas, regardless of its installation date. They stated that lines 109 and 132 are still within their usable lifetimes and that regular maintenance and monitoring are ongoing.
However, from the perspective of the Public Utilities Commission and Stanford officials, this is not sufficient for ensuring the reliability and long-term safety of the sections of the lines for which adequate documentation cannot be found. Possible remedies for the situation would be to perform detailed internal inspection of the pipes, appropriate pressure testing or replacement of the pipe. Until final evaluations and mitigations have been conducted and implemented, a major step taken in the interim to reduce risk has been the reduction of maximum allowable operating pressure in the lines.
Stanford officials will continue to focus on this issue and, as necessary, meet with PG&E representatives to ensure that necessary work will be done to assure the reliability of the gas transmission lines near Stanford property and homeowners. To date, PG&E has not provided Stanford with a timeline for the follow-up evaluation work. As such, Stanford will continue to ask PG&E for additional information and for clarity around projected timetables for PG&E follow-up on inspection of lines 132 and 109 located adjacent to or through university property.