"Nearly two years after the pipeline explosion that killed eight people and devastated a neighborhood in San Bruno, Pacific Gas and Electric Co. considers 239 of its natural-gas transmission lines to be at risk of a similar failure, according to a company assessment obtained by The Chronicle."
"PG&E has identified more than 500 trouble spots on those lines, along sections ranging from a few feet in length to more than a mile, spanning a combined 48 miles. The stretches have pipe-seam welds susceptible to failing because they are old, or because PG&E pressurized the pipes beyond legal limits without testing them afterward for possible problems.
The pipes include two gas lines running along the Peninsula, Lines 101 and 109, and Line 107 in the East Bay between Sunol and Livermore. They also include extensions of Line 132, the pipe that exploded in San Bruno on Sept. 9, 2010.
PG&E's planned solution is to replace some lines and test others with high-pressure water. The state ordered PG&E to conduct such inspections for some lines after the San Bruno disaster, and last year the company checked more than 160 miles of pipe."