Commuters experiencing traffic delays on East Bayshore Road near Embarcadero Road should expect slowdowns for the rest of July. PG&E crews are excavating a gas-transmission line to test for hazardous conditions.
The corrosion inspections are part of an extensive testing project the utility must conduct on parts of its aging infrastructure. The state ordered PG&E to test parts of its network after a segment of Line 132 in San Bruno exploded and caused a massive fire. The incident killed seven people and injured scores of others in September 2010.
Sections of other pipelines including Line 101, which runs through Palo Alto along the U.S. Highway 101 corridor, have come under scrutiny because of a pipe-seam weld that is similar to one implicated in the San Bruno blast.
A PG&E study considers 239 of its natural-gas transmission lines to be at risk of a similar failure, including segments of Line 101 on the Peninsula, the San Francisco Chronicle reported on June 6. PG&E identified more than 500 spots on those lines throughout a 48-mile area that are at risk. The sections have pipe-seam welds that are susceptible of failing due to age or because of excess pressurization that might have weakened the welds, the Chronicle reported.
The stretch of Line 101 in Palo Alto is 2.5 miles long and includes no fewer than five different pipe types, ranging from 20 inches to 36 inches in diameter, according to PG&E. Because of its complexity, testing the pipe has been difficult.
PG&E in November announced it would replace parts of Line 101 in Palo Alto. During a routine inspection June 28, a leak requiring immediate repair was found and fixed, according to the City of Palo Alto.
PG&E plans to install a permanent "in the pipeline inspection device" (PIG) launching station adjacent to East Bayshore to allow ongoing inspections of the line. Construction of this facility is delayed until 2013.
Through July most work should be completed by 4 p.m. along East Bayshore and Embarcadero, but occasionally the job site cannot be adequately secured and work must continue into the commute hours, Debra Katz, Palo Alto Utilities communications manager, noted.
"PG&E's contractor (Mears) cannot walk away from a situation that would cause a safety risk to the public," she said.
The job could be finished by late July, barring unforeseen problems arising during the inspection process. The public can check the status of the work and other PG&E projects in town by visiting the Utilities Department website at www.cityofpaloalto.org/utilities.