2. Background

Located near the Arizona border, the Pacific Gas and Electric Company's (PG&E) Topock Compressor Station (Topock) receives gas from three pipelines: PG&E's Lines 300A and 300B (fed by El Paso Natural Gas' interstate pipeline), and the Transwestern interstate pipeline. Gas coming into Topock is compressed and leaves through Lines 300A and 300B. These lines, which constitute the portion of PG&E's backbone system that bring gas into PG&E's service territory from the Southwest producing basins, terminate at PG&E's Milpitas Terminal. Topock has historically operated at a Maximum Allowable Operating Pressure (MAOP) of 660 pounds per square inch gage (psig).

On February 2, 2011, the Commission's Executive Director ordered PG&E to reduce pressure on all PG&E natural gas pipelines that had experienced pressure increases of greater than 10% of MAOP. This order required PG&E to reduce the operating pressure on the suction side of the Topock compressor station, which had experienced overpressurization to 727 psig, or 1 psig over the authorized 726 psig. The order limited PG&E to operating this segment at 528 psig, or 20% below the authorized MAOP of 660 psig.

On July 11, 2011, PG&E moved for a Commission order delegating authority to the Executive Director to review and approve requests to restore operating pressure on lines where pressure tests had been completed. In Decision (D.) 11-09-006, the Commission denied PG&E's request for a delegation of authority and established an expedited process by which the Commission would review such requests.

On September 12, 2011, and pursuant to D.11-09-006, PG&E filed and served its request to lift the operating pressure restrictions on the suction side of the Topock, along with the required supporting information. PG&E stated that without restoring normal operating pressure, overall pipeline flow rates on PG&E's backbone Lines 300A and 300B will be reduced this winter, and that El Paso Natural Gas will need to resume deliveries to PG&E at the normal (600 psig +) pressures when a Southern California Gas Company line returns to service in late October. PG&E concluded that it needs to return Topock to normal operation to avoid potential curtailments of gas deliveries to its customers this winter.