Gas leak on Oak Street

Atmos Energy workers repair a gas leak near the intersection of West Oak Street and North Cedar Street in July.

Atmos Energy’s latest report to state regulators shows an increase in the number of serious natural gas main leaks in Denton last winter.

Between Dec. 26 and March 8, a “Grade 1” leak caused by corrosion or other pipe problems erupted about once a week in a gas main in Denton. Grade 1 leaks require immediate repair. Crews fixed those 10 leaks and another six like them this spring — including three in a one-week span in April.

The report was filed with the Texas Railroad Commission on July 12 and generally covered the period from Jan. 1 through June 30, although it contained some incidents from the last week of December 2017.

The misnamed Railroad Commission regulates the oil and gas business in Texas, including natural gas utility systems.

According to documents obtained from state officials through an open records request, most Grade 1 leaks in Denton gas mains have been caused by accidental hits to a pipe. However, corrosion and other pipe defects triggered emergency repairs about once every three weeks from 2015 to 2017. The pace of those emergency repairs accelerated to once a week in January and February.

Atmos officials sent a two-page response to questions about the frequency.

“The distribution system in Denton is operating safely,” wrote spokesman John Manganilla. “Unlike in [northwest] Dallas, we did not detect in Denton abnormal, sudden, or unexplained leak activity in February and March of this year.”

The leaks occurred in Denton neighborhoods where Atmos still has steel pipe in the ground. Corrosion caused more major natural gas main leaks in Denton during the first 10 weeks of 2018 than nearly all of 2015 and 2016 combined.

Steel and cast-iron pipe were considered state-of-the-art when installed, but they have not aged well. When it rains, the region’s shifting clay soils can compound the problem. North Texans have learned the hard way that the soil creates new paths for leaking gas to migrate, collect under homes and ignite.

Atmos also reported other leaks that were less serious and did not require immediate repair. The total number of leaks in Denton’s natural gas system caused by corrosion and other pipe problems so far this year comes to 23.

That is just slightly fewer than the 28 leaks Atmos found in a North Dallas neighborhood after a series of fires and explosions, including the Feb. 23 explosion that killed a 12-year-old girl, Linda Rogers. The company shut off service to replace the aging lines in Dallas.

Atmos has come under intense scrutiny this year, having already proposed a $6 billion plan to state officials to systematically replace pipe following several explosions between 2006 and 2009 that killed four people in their homes and injured several others.

In Denton’s case, a pair of Grade 1 leaks erupted within a block of each other on West Hickory and Charlotte streets in January. These gas mains are in a densely populated area west of the University of North Texas where many students and lower-income families live. Crews attributed the cause of both leaks to corrosion. Corrosion also caused four other Grade 1 leaks in central city neighborhoods on either side of Texas Woman’s University during January and February.

Another serious leak in the gas main under Amarillo Street on Jan. 4 was reported as a factory defect. Four days later, on Jan. 8, excessive strain caused a leak in the gas main under Stuart Road. A failed gasket led to a gas main leak under Meadowridge Drive on Jan. 23.

In its latest report to state regulators, Atmos told the Texas Railroad Commission that it will replace a much larger portion of its aging system in Northwest Dallas than was replaced in February and March of this year.

Atmos Energy has replaced 19 miles of distribution main and 3,679 steel service lines in Denton since 2011, Manganilla said.

“This replacement activity will continue as part of our risk-based prioritization model approved by the Railroad Commission of Texas,” he added.

The company also completed a high-pressure pipeline facility replacement that runs from Denton to Shady Shores this year. The next phase will go toward Lake Dallas.

The report, known as the PS-95 report after the rule requiring it, lists hundreds of Grade 1 leaks in the Atmos Energy Mid-Tex system. Atmos serves 1.6 million customers in 514 cities from the Red River south to San Angelo, Kerrville and Bryan. Atmos bought the system in 2004 when it acquired TXU Gas, which began as Lone Star Gas in 1909.

Commission spokeswoman Ramona Nye said that the leak reports are required by rule and are not negotiated plans with the natural gas utility companies. Still, the agency reviews the reports for violation of other state rules.

“During these inspections, if commission rule violations are found as a result of the PS-95 reports or other records evaluated during inspections, operators are cited with violations,” Nye wrote in an email to the Record-Chronicle. “Rule violations would be found in violation reports that are part of a system inspection package completed by the Commission.”

The commission’s rules are meant to protect public safety, Nye added.

“Protection of public safety and our natural resources is the Railroad Commission’s highest priority,” she said.

Other Denton County cities saw Grade 1 leaks, too. During the first six months of 2018, there were 16 Grade 1 leaks in the Denton County neighborhoods of Carrollton, as well as six in Flower Mound, five in Lewisville and two each in Pilot Point and Little Elm. There were also Grade 1 leaks in Aubrey, Justin, Roanoke and The Colony.

Manganilla said the company wants the public to be a partner in safety.

“Our focus has and always will be on the safe operation of our system,” Manganilla said. “We actively promote natural gas safety by educating the public about how to detect leaks and prevent accidents.”

Atmos also reported about 100 other leaks in Denton County cities that did not require immediate repair, the report showed.

PEGGY HEINKEL-WOLFE can be reached at 940-566-6881 and via Twitter at @phwolfeDRC.

By the Numbers

Here’s a comparison of the cause of Grade 1 leaks in Denton in the past three years and the first six months of 2018. (Note that this chart does not include Grade 1 leaks caused by third-party excavators and similar damage.)

Field 1 2015 2016 2017 2018 (partial)
Corrosion 4 3 7 7
Ground movement 5 1 1 1
Excessive strain 2 1 2 3
Factory Defect 4 1 1 2
Gasket or O-ring 4 2 1 7
Stripped Threads 6 3 5 4
Failed to follow procedure 1
Weld 1
Fusion defect (plastic) 1 4 1
Packing 1
Total Grade 1 leaks 26 14 21 25

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