Pacific Gas and Electric Co. (PG&E) said last Friday that a slow drop in pressure occurred during a hydrostatic pressure test on a portion of the same 30-inch diameter transmission pipeline (Line 132) involved in last year’s deadly San Bruno rupture near Palo Alto. It turned out to be a small pinhole leak of approximately one millimeter in diameter, a situation that PG&E stressed was safe with no customer impacts. This is the second recent incident in the utility’s ongoing intensive pipeline testing program prompted by San Bruno (see Daily GPI, Oct. 26). PG&E said the water leak was detected during the initial phase of a hydrostatic pressure test at 75% of the test pressure for one hour. The pressure at the time of the leak was 525 psig; Line 132’s maximum allowable operating pressure is 400 psig. Its normal operating pressure is 375 psig and it is currently operating at a reduced pressure of 300 psig, mandated since the San Bruno incident. PG&E said it will identify the exact location of the leak in the next few days, excavate, make repairs and then reconduct the hydrostatic pressure test.
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