The National Transportation Safety Board unanimously found Atmos Energy had “inadequate” pipeline management and an “insufficient” leak investigation that contributed to “inaction” in evacuating a northwest Dallas neighborhood that had three gas-related incidents. Those incidents included a fatal explosion that killed a 12-year-old Linda “Michellita” Rogers.
The five-member NTSB found that the probable cause of the Feb. 23, 2018 fatal explosion at 3534 Espanola Drive was “the ignition of an accumulation of natural gas that leaked from the gas main that was damaged during a sewer replacement project 23 years earlier, and was undetected by Atmos Energy Corporation’s investigation of two related natural gas incidents on the two days prior to the explosion.”
In a public online hearing Tuesday, the NTSB members largely concurred with Board staff findings and recommendations as part of a nearly a 3-year-long investigation.
In a one-page statement, Atmos Energy responded by giving its “deepest sympathies” to Roger’s family, and said the company’s “number one priority is the safety of the public, our employees and our natural gas distribution system.”
“We believe that the probable cause is reflected in the NTSB finding that the natural gas main was damaged by excavation equipment,” the statement said.
NTSB did find that the probable cause of the leak was damage to a 71-year-old natural gas main that was about a half inch below a sewer line. But the NTSB also had other findings, including the following:
- “Atmos Energy did not adequately investigate the first two gas related incidents that occurred at 3527 and 3515 Durango Drive.”
- “Had Atmos Energy Corporation pressure-tested the (gas) main in the alley behind the first two homes on February 21 or Feb. 22, 2018, it could have found the (gas) main did not hold pressure spurring additional protective actions that could have prevented the fatal explosion at 3534 Espanola Drive.”
- “Though Atmos’ distribution integrity management program is generally consistent with industry guidance, it did not adequately consider threats degrading the system.”
In particular, the NTSB was troubled by an Atmos Energy technician’s initial reliance on “bar hole testing,” poking a sensor into the ground. The technician found no evidence of gas in a 30-minute review near the first natural gas incident.
The NTSB staff, however, concluded that relying on bar hole testing in wet conditions during the February gas fires and explosions was “an indication of integrity management deficiencies.”
“You do not see two houses have natural gas issues a day apart on the same street unless there is an external source,” Robert Hall, the NTSB’s director of the office of railroad pipeline and hazardous material investigations, told the board.
Sara Lyons, who oversaw the NTSB staff investigation also told the NTSB that their findings indicated that the decision to shut off gas and possibly evacuate the neighborhood should have been sooner.
“We believe they should have shut down the system,” Lyons said. “…I believe we said they should've evacuated the houses and prevented access to those houses and the emergency shut down and, of course, they did not do that…”
NTSB member Michael Graham said the findings also had him concerned.
“I don't understand why Atmos did not shut off the gas,” Graham said. “I don't get it. I know it's easy to be what I call an ‘armchair quarterback’ after the fact but I have always taken the most conservative route in my operations and it seems like they should have shut it down to figure out what was going on before they allowed anything else to happen.”
Dallas Fire-Rescue responded in 2018 and put out the first two natural gas fires in a timely fashion. But the NTSB and staff cited DFR for failing to have a team with special natural gas training to recognize the possibility of a larger gas leak and prompting “further investigation or regulatory oversight prior to the (fatal) explosion.”
“The assistance of the Fire Rescue Department's hazardous material response team - particularly after the second incident - could have enhanced Atmos Energy Corporation’s leak investigation,” the NTSB found.
During the hearing, the NTSB staff showed a photo of the damaged pipe with a dent on the top and cracks on the side. The staff believed the damage was “typical of third-party damage resulting from digging operation from above ground.”
“The severity of the damage is consistent with those caused by excavation equipment and not from a shovel,” one of the staffers reported. “Based on these observations the dent and gouge damage most likely resulted when the sanitary sewer lateral was replaced in 1995.”
Following the fatal explosion, investigators found 741 significant leaks over 5 weeks, in and around the Northwest Dallas neighborhood.
Atmos contracted with a company to do a review that found at least some of the problems could not be anticipated. That prompted the NTSB to contract with the Corps of Engineers to do a study of their own on the validity of the company’s report. The results of the study, however, conflicted with Atmos’ report.
The NTSB concluded:
- “The high number of leaks observed in northwest Dallas after the explosion were due to the degradation of Atmos energy Corporation's gas distribution system, not sudden and unanticipated geologic loadings."
Dallas Attorney Ted Lyon, who represented Roger’s family, said the NTSB findings confirmed what he knew two years ago when they filed a lawsuit.
“The Board confirms that Atmos operated these gas lines not only negligently, but grossly negligently,” Lyon told WFAA. “Everything that we pointed out in our lawsuit has turned out to be true.”
“Atmos had a 71-year-old pipe in the ground that should have been replaced 20 or 30 years ago but continued to operate,” Lyon said. “They knew gas was leaking in the neighborhood but failed to correct.”
“There are thousands of miles of that type of pipe in Dallas County that needs to be replaced,” Lyon said.
As a result, the NTSB recommended that Dallas Fire-Rescue do the following:
- Revise its continuing education requirement for arson investigators for training on building and fuel gas systems.
- Revise procedures to require gas monitoring after the occurrence of a gas related structure fire or explosion.
- Develop and implement a formal process to alert federal agencies of potential systemic safety issues that should be investigated further.
The NTSB also recommended Atmos Energy do the following:
- Provide initial and training to Dallas Fire-Rescue Department on natural gas distribution and hazards.
- Develop and implement more rigorous inside leak investigation requirements in response to fires and possible gas explosions, including clear guidance on pressure testing.
- Develop a clear procedure to coordinate with emergency responders when investigating all fires and explosions that may be gas related.
- Revise policies and procedures for responding to leaks, fires and explosions and emergency calls to address the challenges caused by wet weather conditions, including revising policies and procedures to have a leak investigation method that is reliable in wet weather.
Lyon also said he agreed with NTSB’s concerns about “odorant fade” in which the smell of the odorant fades or leaches out as the gas moves through the soil. Families contacted by NTSB investigators said they did not smell the natural gas odorant prior to the fires or explosion.
“No one in that neighborhood where they had three explosions smelled stinky gas, and the gas was everywhere,” Lyon said. “Everyone in Dallas County needs a gas detector in their homes.”