PG&E Welcomes Opportunity To Demonstrate Safety Of Line 147
SAN FRANCISCO, Oct. 8, 2013 /PRNewswire/ -- Pacific Gas and Electric Company (PG&E) today said it welcomes the opportunity to continue its work with the California Public Utilities Commission and San Mateo County communities to validate that the company has completed, as represented, safety-related work on transmission Line 147.
"We want to be a good neighbor to San Mateo County communities. Customers in these communities can be assured that Line 147 is safe and we look forward to the opportunity to document all the work that has gone into maintaining and operating this line safely. It is important that this validation be completed on an expedited basis because Line 147 is even more critical to our system once colder weather comes our way. We don't want to be in a position of being unable to serve our customers because the pipeline is out of service," said Nick Stavropoulos, the executive vice president responsible for leading the PG&E gas organization since June 2011.
PG&E on Friday was ordered by a San Mateo Superior Court to cease service to Line 147 after the City of San Carlos questioned the pipe's safety. The company complied with the order and today said it does not intend to return the line to service pending a review by the CPUC. However, the company today asked the Court to vacate the temporary injunction because it lacked the jurisdiction to make such a ruling. In California, exclusive jurisdiction is given to the California Public Utilities Commission in order to avoid a patchwork of conflicting local standards and regulations.
What is Line 147 and where is it located?
Line 147 consists of a 20-inch and 24-inch gas pipeline that runs for 3.8 miles between Highways 101 and 280 along Brittan Avenue in San Carlos (PG&E Gas Transmission Pipelines). Line 147 plays an important role in PG&E's ability to safely and reliably serve more than 650,000 customers on the Peninsula. Line 147 is a cross-tie, connecting Line 101 on the eastern side of the Peninsula to Lines 109 and 132 that are centrally located on the Peninsula. Lines 101, 109 and 132 run south to north from Milpitas Terminal in Santa Clara County to PG&E's San Francisco Gas Load Center.
What measures has PG&E taken to ensure the safe operation of Line 147?
Our work on Line 147 has included verifying records and pressurizing the line with high-pressure water to confirm its integrity. PG&E employees – on foot and in the air – have regularly checked this line, and all of PG&E's lines, for leaks.
Following the San Bruno accident in September 2010, PG&E lowered the operating pressure on many pipelines – including Line 147 – as an interim safety measure. In addition, after the San Bruno accident, the National Transportation Safety Board (NTSB) recommended hydrostatic testing for pipelines that were previously not subject to a pressure test – a process whereby water is put into the line at nearly double, if not more, the pressure that the gas typically reaches – be performed across all gas utilities in the nation.
In October of 2011, Line 147 was hydrostatically tested, and passed. Because of this successful pressure test, PG&E asked the CPUC to allow it to restore the line's operating pressure. This request included a large volume of documentation and evidence supporting this restoration of pressure.
After receiving approval from the CPUC, PG&E increased the operating pressure on Line 147 as necessary to meet winter load, but kept the operating pressure below the approved Maximum Allowable Operating Pressure (MAOP). On May 24, 2012, after the winter months, PG&E again reduced the operating pressure on Line 147.
Additional measures taken to ensure safe operation of Line 147
In addition to the pressure test, PG&E has taken extensive actions since 2010 to ensure the continued safe operation of Line 147. These have included:
- MAOP Validation: Using its Pipeline Features List, PG&E conducted a systematic evaluation of the characteristics of Line 147 to validate the MAOP of each pipeline component.
- Integrity Assessment: PG&E has completed baseline assessments for the portions of Line 147 that are in densely populated areas, by performing External Corrosion Direct Assessments in 2004 and/or 2009.
- Valve Replacement: A new 20-inch valve was installed on Line 147 near Brittan Avenue in 2011 to allow PG&E to quickly stop the flow of gas and isolate the line if necessary.
- Regular Maintenance:
- Leak Surveys: All of Line147 was surveyed in April 2013. PG&E continues to survey Line 147 for leaks on a regular basis.
- Ground and Aerial Patrols: PG&E has conducted ground patrols of Line 147 in each of the first eight months of 2013 as well as in November and December of 2012. During these patrols, PG&E gas employees walk or drive the line to check for any leaks. PG&E also has conducted aerial patrols on Line 147 every month from December 2012 to date, except for February 2013. PG&E continues to patrol and monitor these lines and records observations of any potential threats to the integrity of the lines.
- Anti-Corrosion Measures: Line 147 is equipped with cathodic protection (CP), a system to safeguard against pipeline corrosion. PG&E inspects its CP systems using pipe-to-soil reads, and annual rectifier inspections. This electrical device impresses current on the pipeline, which is a critical part of the corrosion control system. PG&E continues to perform CP pipe-to-soil inspections on Line 147 every other month.
A leak was discovered as part of routine work
In October 2012, as PG&E continued other work to improve the safety of its system, a leak was found on Line 147. At the same time, the company discovered discrepancies in the information that was originally submitted to support the pipeline's MAOP.
As part of PG&E's due diligence into the leak, a contractor raised questions about Line 147 in an email. That's exactly what we encourage our people to do: raise any concerns about safety. All of the issues raised by the individual were seriously discussed.
PG&E also removed the section of pipe that leaked to confirm its mechanical and metallurgical properties via laboratory work, including a root cause analysis of the leak itself. That report concluded the leak was on base metal, not on a girth weld or the long seam weld and, importantly, that "no evidence of crack growth during service or hydro testing was detected."
The results of this metallurgical test, the results of the 2011 hydrostatic pressure tests, and other steps PG&E has taken to ensure the integrity of its system, confirm that Line 147 is safe.
To learn more about PG&E's commitment to pipeline safety, please visit www.pge.com/pipelinesafety.
Pacific Gas and Electric Company, a subsidiary of PG&E Corporation (NYSE: PCG), is one of the largest combined natural gas and electric utilities in the United States. Based in San Francisco, with 20,000 employees, the company delivers some of the nation's cleanest energy to 15 million people in Northern and Central California. For more information, visit: http://www.pge.com/about/newsroom and www.pgecurrents.com.
SOURCE Pacific Gas and Electric Company