III. FACTUAL BACKGROUND

The CPSD Report and the NTSB Report (of which we take official notice herein) provide the following summary factual background. The PG&E transmission pipeline segment that ruptured under the San Bruno, California neighborhood on September 9, 2010, was installed in 1956. (CPSD Report, p.7.) The section of pipeline involved in the incident was Segment 180 of PG&E's Line 132. (Ibid.) The segment was constructed of longitudinally seam-welded pipe. When the pipe was installed, various segments, or "pups," of the pipe were joined together with circumferential welds, referred to as "girth" welds. (CPSD Report, p.17.) The San Bruno segment of this pipeline was located in a neighborhood the U.S. Department of Transportation classifies as "high consequence," meaning "any area where a potential impact radius of 660 feet would contain more than 20 buildings intended for human occupancy." (49 C.F.R. Section 192.903, and NTSB January 3, 2010 Safety Recommendation, p. 2, Appendix B).

Segment 180 that ruptured in San Bruno was a 30-inch diameter transmission pipeline. It was used to transport large quantities of gas at high pressure from Milpitas, California, north through the Bay Area Peninsula and to the City of San Francisco. (CPSD Report, p.7.) Line 132 is part of a series of three transmission pipelines that provide 100% of the natural gas consumed by residential, commercial and industrial customers, as well as power plants, in San Francisco and along the Peninsula. Line 132 originates at the terminus of a larger pipeline at Milpitas, at a PG&E owned and operated facility known as the Milpitas Terminal. (Ibid.)

The NTSB examination showed that the 27 foot 8 inch segment of pipe that was hurled from the ground by the rupture consisted of four joined "pup" pipes, and one "long joint" pipe, all welded together by circumferential or "girth" welds. The NTSB examination also appears to demonstrate that all components of the 28 foot ruptured pipe were longitudinally welded. (NTSB January 21, 2011 Materials Laboratory Factual Report, p.2, Appendix C.)

During the afternoon of September 9, 2010, PG&E personnel were working on an uninterruptable power supply system at the Milpitas Terminal, about 39.33 miles southeast of the San Bruno rupture site. (CPSD Report, p.8.) The Milpitas Terminal serves as a receiving point for natural gas coming from the northern and southern portion of the state. (Id., p.74.) At 5:21pm, a short circuit occurred in the wiring as the work was being completed, causing pipeline pressure measuring devices to lose power. This in turn caused the pressure regulating valves on Line 132 to move to full open, which caused the pressure to increase to at least 396 psig. (Id., p.95.) According to PG&E's SCADA system, the highest pressure recorded at an upstream location closest to Segment 180 just prior to the failure was 386 psig. (Id., p.8.) Based on a review of historical pressure data, this was the highest pressure Segment 180 had experienced within the seven years preceding the rupture. The previous maximum pressure on Segment 180 was 382.98 psig in December 2003. (Ibid.)

Both the NTSB Report and the CPSD Report indicate significant deficiencies in PG&E's emergency response to the rupture and explosion. These deficiencies contributed to a delay of 95 minutes in isolating the rupture to stop the flow of gas, along with the lack of either automatic shutoff valves or remote control valves on the line, which contributed to the severity and extent of property damage. (NTSB Report, Executive Summary, p.x.) The local fire department set up an Incident Command within 10 minutes. (NTSB Report, p.13.) More than 900 emergency responders from the city of San Bruno and surrounding jurisdictions executed a coordinated emergency response, which included defensive operations, search and evacuation, and medical operations. (NTSB Report, Executive Summary, p.x.) Once the flow of natural gas was interrupted, firefighting operations continued for 2 days until the fire was extinguished.