But DBI spokesperson Bill Strawn said, "Those questions you were asking really don't fall into the Department of Building Inspection's jurisdiction."
Strawn added that the issue of underground infrastructure is not really taken into account when building permits are issued. "We don't go to the [Public Utilities Commission] or [Department of Public Works] or PG&E" for that kind of information, Strawn said. "That would be the responsibility of the property owner, and the plans they submit to us don't include that kind of utility information."
PG&E is scrambling to meet a March 15 deadline imposed by the California Public Utilities Commission to turn over records proving its lines are intact. Until it can prove the integrity of its system either on paper or through costly, high-pressure water testing, the condition of some lines is unknown. PG&E did not return calls for comment.
In San Francisco, a densely populated urban hub on an earthquake-prone peninsula where major development projects are being permitted all the time, these issues are particularly pressing. Charley Marsteller, former chair of San Francisco Common Cause, certainly thinks so.
Last December, Marsteller penned a letter to a well-respected geotechnical engineer, raising a question about pipeline safety in light of California Pacific Medical Center's plans to construct a massive hospital at its Cathedral Hill site on Franklin Street. According to a map of underground gas lines published by the Guardian (See "PG&E's Secret Pipeline Map," 9/21/10) using several sources of data, a PG&E gas main appears to run beneath Franklin.
Marsteller was worried about whether excavation for CPMC — or other projects requiring excavation, or even simple contractor digging — could cause vibrations that could affect that pipe.
"As CPMC digs its 100-foot hole, and due to the massive construction vibrations, is there not a risk that the PG&E gas pipeline is at risk of rupture?" he wanted to know.
The engineer, who preferred not to have his name published, responded in an informal letter that "it is indeed possible that soil movement generated by excavation and/or foundation construction could rupture a deteriorated gas main." He added that while he wasn't familiar with the details of CPMC's or other excavation projects on Franklin Street, he did know that the area in question "consists of relatively weak soil" underlain at depth by a geologic feature called the Franciscan Formation, made of sandstone and fine-grained, sedimentary rock.
Yet no one seems to be giving this question any kind of professional attention or study. Eerily, Marsteller seems to be the only person in San Francisco who's asking what happens if a major excavation project is permitted nearby a corroded pipeline — and he says he hasn't received much of a response from the "rather blistering memos" he's fired off to planning commissioners and members of the Board of Supervisors to ask about it. "I'm very concerned that we're not suspending contractor digging proximate to a pipeline," Marsteller said, until PG&E can offer proof that the lines nearby excavation projects are in good shape. Whether these issues will ever be considered as part of the local planning process, Marsteller predicted: "The answer is, no one ever thinks about this."
Excavation damage accounts for nearly one-quarter of pipeline "incidents" nationwide, according to the federal Office of Pipeline Safety report. Yet safeguards are in place to prevent these things from happening.