Business & Tech

PG&E Starts Earthquake Retrofit Work on Line 132

The project will install a new section of gas transmission pipe near Colma Creek in South San Francisco, prompted by the results found in an inline video inspection performed on Line 132 in June.

PG&E construction crews are beginning work today on a segment of Line 132 in South San Francisco that is expected to ensure the integrity of the pipeline if a major earthquake occurred, the utility said. 

The project will install a new 1-mile gas transmission pipeline near Colma Creek and was prompted by the performed on the pipeline in June after it was hydrostatically tested. According to PG&E, experts looked at the pipe—a 3-mile segment that runs from PG&E’s Healy Station on Crestwood Drive in San Bruno to Hillside Boulevard in South San Francisco, about a mile away from the site of the Sept. 9, 2010, explosion—and discovered that it was in what is known as a liquefaction zone, meaning the soil surrounding the pipe could shift. 

"PG&E’s own hydrostatic pressure tests on the line, plus a report from an independent consultant, confirmed that the older pipeline can be operated safely," PG&E said in a statement on its PG&E Currents website. "However, it was determined that if a significant seismic event occurred resulting in soil liquefaction then some of the welds on the older pipeline might not perform as required." 

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Crews will insert a 24-inch pipeline inside the existing 30-inch pipeline, a temporary move but one that will enhance the safety of the utility's system throughout the Peninsula, said a PG&E spokeswoman. 

"What we're doing is putting in a new 24-inch pipe…to, one, make it safer if a major earthquake struck and, two, help us meet the winter demand," said PG&E spokeswoman Brittany Chord. 

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The piece of Line 132 that is being replaced is part of a segment that has been out of service since this spring. PG&E plans to put it back in service once the temporary pipe is installed. That work should be completed by December, Chord said. 

Next year, the pipe will be completely replaced by a new 30-inch segment in addition to the rest of the 3-mile pipe segment, Chord added. 

PG&E said it has already informed the cities that will be impacted by the construction work and the California Public Utilities Commission. 

When asked whether the cost to replace the pipe would be passed down to the ratepayers, Chord said PG&E hasn't yet made that decision. 

"We're still determining the scope of the work," she said. "Once we have a better idea of the scope, we'll determine the cost and take that to the CPUC." 

Crews, using excavators, water tanks and other heavy equipment, will be working between 7 a.m. and 7 p.m. Monday through Friday, and from 8 a.m. to 7 p.m. on weekends and holidays. 

For more information about the work, call PG&E's gas transmission pipeline hotline at 888-743-7432 or visit PG&E's natural gas system website.


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