California Energy Markets / Bottom Lines
[July 6, 2018 / No. 1495]
SoCal Gas Opens Black Box Surrounding Line 235-2 Rupture
The Oct. 1, 2017, rupture of Southern California Gas Co.'s Line 235-2 near Newberry Springs was caused by external corrosion, the utility disclosed in a June 29 letter to the California Public Utilities Commission.
Line 235-2, referred to by SoCal Gas as Line 235 West, is a backbone natural gas transmission line that carries gas westward from the Newberry Springs Compressor Station in the Mojave Desert. The October rupture created a large crater and damaged Line 4000, a nearby backbone transmission line that also carries gas out of the Newberry station westward. Line 4000 was placed back in service Dec. 30 at reduced capacity.
The incident upended the natural gas market in California. Gas prices spiked at the SoCal CityGate hub during two cold snaps over the winter, and outage-related reliability issues continue in the region, leading regulators to call for an increase in the amount of gas stored at SoCal Gas' Aliso Canyon natural gas storage field (see CEM No. 1393 ).
Line 235-2 experienced a "leakage failure that led to rupture and ignition," SoCal Gas reported in the letter, which responded to a June 18 CPUC letter asking the utility to formally explain why Line 235-2 and a third line, Line 3000, have been out of service for an extended time, and how the utility is treating the pipelines in rates. (SoCal Gas' short answer on rate treatment is that both lines are still included in its revenue requirement.) SoCal Gas hired quality assurance and risk-management company DNV GL to conduct a metallurgical analysis and a root-cause analysis; DNV GL completed the metallurgical analysis and determined the underlying cause by Nov. 30, according to the utility.
Both Line 235 West and Line 3000 have been undergoing integrity assessment and remediation work, according to the utility.
It's unclear whether the current integrity work and remediation for Line 235 that SoCal Gas discussed in its letter was started after the rupture, or before.
But the utility several years ago identified numerous safety-related conditions that required taking the line out of service for seven months to perform pipeline-replacement work.
Phase 1 of SoCal Gas' previous Line 235 West work included portions of the line installed in 1957 that run about 46 miles from the Newberry Springs Compressor Station to the utility's mainline valve No. 17, in Victorville. In 2014, SoCal Gas completed an in-line assessment of this stretch of line; the assessment identified 51,140 potential anomalies, including 11 safety-related conditions, according to the utility. Under federal code, such safety-related conditions require immediate attention, and SoCal Gas replaced 0.8 miles of pipe at 61 separate sites, primarily to address external corrosion, the company said.
In-line assessments generate reams of data; the assessments can also mischaracterize issues, so utilities prepare thorough validation plans to analyze the in-line assessment data and develop a remediation plan.
Several things remain publicly unknown about the rupture. It's unclear whether the 2014 in-line assessment identified any problems with the pipeline at the site of the rupture, for example, and if it did, whether it was part of the remediation project. It's also unclear whether, if issues were identified in 2014, the CPUC was notified; and if the commission was notified, what action, if any, it took.
SoCal Gas did not respond to several questions about the 2014 work and the 2017 rupture.
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The CPUC on June 28 denied a Public Records Act request from California Energy Markets seeking information about the rupture, citing Res. L-272, a 1998 resolution stemming from a request by two media outlets for CPUC records. That resolution concluded in part that investigative records maintained by commission staff can be exempt from disclosure to the public under a specific exemption in the PRA (Section 6254(f)), if they are created "when the prospect of an enforcement proceeding is concrete and definite."
To date, the CPUC has not opened any formal investigation or enforcement proceeding related to the October incident.
The CPUC did not make anyone available to comment by press time.
According to SoCal Gas, DNV GL completed its root-cause analysis and recommendations for next steps on April 27; recommendations from the consultant include enhancements to SoCal Gas' in-line data analysis and cathodic-protection data integration practices.
"Implementation of recommended in-line inspection data and analysis improvements will assist SoCal Gas in developing better-informed maintenance and repair plans," the company stated in its letter to the commission. "The recommended cathodic protection practice enhancements will promote better corrosion evaluation and prevention into the future."
SoCal Gas' initial remediation plan based on DNV GL's metallurgical report, root-cause analysis and recommendations calls for replacing 3.4 miles of pipeline, which would require permitting at six locations. SoCal Gas said a best-case scenario would be the work is completed in nine months. Once the initial remediation work is done, the utility would return the Phase 1 portion of the line to service at a reduced operating pressure until all the root-cause analysis recommendations can be implemented. The letter did not detail results of the root-cause analysis.
The work being done on Line 3000, dubbed the Line 3000 East Project, is extensive and complex due to a number of construction and environmental challenges—ranging from the need to reinforce dirt roads and narrow one-way roads to a 10-mph speed limit in some areas—as well as a need to take precautions to ensure the safety of threatened species, including the desert tortoise. In this area, elevation ranges from 1,500 feet to 3,000 feet, which presents another challenge.
In 2010, using advanced in-line inspection technology, SoCal Gas found several instances of external corrosion on Line 3000, which was installed in 1957 and which runs about 125 miles, from South Needles to the Newberry Springs Compressor Station. Four miles of pipeline were replaced to remediate the corrosion, and the line was out of service for a year.
Another assessment was done in 2016, this time in two phases. The first phase of that work assessed an 8-mile portion of line, identified 1,382 potential anomalies for further assessment and one safety-related condition. That work was completed in December 2016.
For the second phase of this work on Line 3000, a 117-mile portion of line was assessed, generating 300 gigabytes of data; the utility ultimately identified 22,291 potential anomalies for further validation. A preliminary report for this portion of line identified 13 safety-related conditions. SoCal Gas has been remediating these issues since then, and expects to complete all remediation work this September. –Mavis Scanlon
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