NTSB Safety Recommendation P-21-009

NTSB safety recommendation P-21-009.

TO ATMOS ENERGY CORPORATION: Develop and implement more rigorous inside leak investigation requirements in response to fires and explosions when gas involvement cannot be excluded, including clear guidance on pressure testing and inside gas measurements and the potential need to return to the property after firefighters have departed.

Priority: CLASS II

Overall Status: Closed - Acceptable Action

Issued Date: 2021-02-08

Adopted Date: 2021-01-12

Overall Date Closed: 2022-05-11

Synopsis: On February 23, 2018, at 6:38 a.m. local time, a natural gas–fueled explosion occurred at 3534 Espanola Drive, Dallas, Texas. The residence sustained major structural damage, but when first responders arrived on scene at 6:44 a.m., they observed no smoke or fire. Four family members were injured, and one was killed in the explosion. Following the explosion, National Transportation Safety Board (NTSB) investigators located a through-wall crack in the 71 year old natural gas main that served the residence. In the 2 days before this explosion, two gas-related incidents occurred on the same block at houses that were served by the same natural gas main, each resulting in significant structural damage and burn injuries to one occupant. The first occurred on February 21, 2018, at 5:49 a.m., and resulted in one injury involving second-degree burns and significant structural damage to 3527 Durango Drive. The second incident occurred on February 22, 2018, at 10:21 a.m., and resulted in one injury involving second-degree burns and significant structural damage to 3515 Durango Drive. As a result of this investigation, the NTSB issued new safety recommendations to the Pipeline and Hazardous Materials Safety Administration, the Railroad Commission of Texas, the Dallas Fire-Rescue Department, Atmos Energy Corporation, and the Gas Piping Technology Committee. The NTSB is also reiterating safety recommendations to the International Code Council, the National Fire Protection Association, and the Gas Technology Institute

Probable Cause: The National Transportation Safety Board determines that the probable cause of the 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 2 days prior to the explosion. Contributing to the explosion was Atmos Energy Corporation’s insufficient wet weather leak investigation procedures. Contributing to the severity of the explosion was Atmos Energy Corporation’s inaction to isolate the affected main and evacuate the houses. Contributing to the degradation of the pipeline system was Atmos Energy Corporation’s inadequate integrity management program.

Ntsbnumber: PLD18FR002

Report Number: PAR-21-01

Addressee Name: ATMOS Energy Corporation

Addressee Status: Closed - Acceptable Action

Addressee Date Closed: 2022-05-11

Addressee Organization Type: P-Private Industry

Communication Date: 2021-02-08

Communication Type: Transmittal Letter

Communication Contents: The National Transportation Safety Board (NTSB) is an independent federal agency charged by Congress with investigating every civil aviation accident in the United States and significant accidents in other modes of transportation—railroad, highway, marine, and pipeline. We determine the probable cause of the accidents and issue safety recommendations aimed at preventing future accidents. In addition, we carry out special studies concerning transportation safety and coordinate the resources of the federal government and other organizations to provide assistance to victims and their family members affected by major transportation disasters. The attached letter from the NTSB Chairman provides information about the NTSB’s January 12, 2021, report Atmos Energy Corporation Natural Gas-Fueled Explosion, Dallas, Texas, February 23, 2018, PAR-21/01. The details of this accident investigation and the resulting safety recommendation may be found in the attached report, which can also be accessed at http://www.ntsb.gov. For more information about NTSB and our recommendation process, please see the attached one-page summary. The NTSB is vitally interested in these recommendations because they are designed to prevent accidents and save lives. We would appreciate a response within 90 days of the date of this letter, detailing the actions you have taken or intend to take to implement these recommendations. When replying, please refer to the safety recommendation by number (for example, P 21 8 through -12). We encourage you to submit your response to ExecutiveSecretariat@ntsb.gov. If your reply exceeds 20 megabytes, including attachments, please e mail us at the same address for instructions on how to send larger documents. Please do not submit both an electronic copy and a hard copy of the same response. All communications regarding safety recommendations will be stored by the NTSB and viewable by the public. Please do not send privileged or confidential communications in response to this recommendation. Responses marked as confidential or privileged (or similar designations) will be considered nonresponsive. If you have concerns about this protocol, please contact us at ExecutiveSecretariat@ntsb.gov. The National Transportation Safety Board (NTSB) is an independent federal agency charged by Congress with investigating every civil aviation accident in the United States and significant accidents in other modes of transportation—railroad, highway, marine, and pipeline. We determine the probable cause of the accidents and issue safety recommendations aimed at preventing future accidents. In addition, we carry out special studies concerning transportation safety and coordinate the resources of the federal government and other organizations to assist victims and their family members affected by major transportation disasters. We are providing the following information to urge Atmos Energy Corporation (Atmos) to act on the safety recommendation in this letter because we believe your organization can help reduce the risk of future accidents. For more information about the NTSB and our recommendation process, please see the attached one-page summary. This letter provides information about the National Transportation Safety Board’s (NTSB) January 12, 2021, report Atmos Energy Corporation Natural Gas-Fueled Explosion, Dallas, Texas, February 23, 2018, PAR-21/01. The details of this accident investigation and the resulting safety recommendations may be found in the attached report, which can also be accessed at http://www.ntsb.gov. As a result of this investigation, we identified the following safety issues: • Incident investigation. Neither Dallas Fire-Rescue Department (DFR) nor Atmos identified the causes of the two incidents that occurred in the days immediately preceding the explosion. DFR arson investigators and Atmos technicians did not effectively investigate, communicate, or collaborate to determine the cause of either incident. Further, Atmos did not gather enough evidence to determine if gas migrated from their piping and fueled the first two incidents. • Leak investigations and repairs. Atmos dedicated significant resources to its response following the second incident, finding 13 leaks determined to present an existing or probable future hazard. However, none of its employees questioned the integrity of the system. As a result, Atmos did not take appropriate action to secure the safety of the area and its residents. This was attributed, in part, to inadequate procedures for performing leak investigations in wet weather conditions. • Methane detection. Although Atmos added odorant to its gas distribution system in a manner consistent with Pipeline and Hazardous Materials Safety Administration (PHMSA) regulations, none of the residents at any of the affected homes smelled gas. Although odorant can act as an early warning of a gas release to prevent an explosion and fire, it is known to become depleted if it travels through soil. • Incident reporting. Incident reporting requirements mandated by the PHMSA rely on the judgement of the operator to determine whether an incident resulted from a leak in their system and do not specify the level of investigation necessary to make the determination. While operators have an option to report events that may have been caused by their system, Atmos relied on an incomplete investigation to support its position not to report the first two incidents. Accordingly, the NTSB makes the following safety recommendations to Atmos. Additional information regarding these recommendations can be found in the noted sections of the report. • Provide initial and recurrent training to Dallas Fire-Rescue Department arson investigators and firefighters on the local natural gas distribution system and associated hazards. (P 21 8) (See section 2.3.1.) • Develop and implement more rigorous inside leak investigation requirements in response to fires and explosions when gas involvement cannot be excluded, including clear guidance on pressure testing and inside gas measurements and the potential need to return to the property after firefighters have departed. (P 21-9) (See section 2.3.2.1.) • Develop a clear procedure to coordinate with local emergency responders when investigating all fires and explosions that may be gas related to conclusively determine whether your system can be excluded as a potential contributor, and collecting the necessary evidence to support the conclusion of your investigations. (P 21-10) (See section 2.3.2.3.) • Revise your policies and procedures for responding to leaks, fires, explosions, and emergency calls to address the challenges caused by wet weather conditions. The revised policies and procedures should include: (1) leak investigation methods that are reliable in wet weather; (2) leak investigation procedures that assess all viable gas migration paths; (3) criteria for when to shut down or isolate gas distribution systems and pressure test main and service lines; and (4) an alternate safe response such as evacuation when reliable leak investigations are not possible due to wet weather or other circumstances. (P-21-11) (See section 2.4.) • Without delay, assess your integrity management program, paying particular attention to the areas identified in this investigation, and revise the program to appropriately consider: (1) threats that degrade a system over time, and (2) the increased risk that can result from factors that simultaneously increase the likelihood and consequence of failure. (P 21 12) (See section 2.7.) The NTSB is vitally interested in these recommendations because they are designed to prevent accidents and save lives. We would appreciate a response within 90 days of the date of this letter, detailing the actions you have taken or intend to take to implement these recommendations. When replying, please refer to the safety recommendatio

Addressee Organization Type: P-Private Industry

Communication Date: 2021-05-07

Communication Type: Official Correspondence

Communication Contents: Kevin Akers, President and CEO: Atmos Energy submits this letter and attachments in response to the National Transportation Safety Board (NTSB)’s letter dated February 8, 2021 concerning the NTSB’s January 12, 2021 Report on the incident that occurred in Dallas, Texas on February 23, 2018. As the attached responses reflect, we have either already, or soon will be, implementing the NTSB Recommendations P-21-8 through P-21-12. Our focus on safety has continued throughout this investigation, including voluntary initiatives to reduce the risk of third-party damage to our pipelines. In addition to the enhancements reflected in the Safety Recommendations, because third party damage remains one of the greatest threats to natural gas distribution systems, we have been and will continue to be a champion for damage prevention. We are committed to continuous improvement on our journey to achieve our vision to be the safest provider of natural gas services. Atmos Energy appreciates the opportunity to respond to the NTSB and we look forward to continuing to work closely with the NTSB to further enhance the safe delivery of natural gas services. Atmos Energy appreciates the work of the NTSB in connection with its response to the incident on February 23, 2018, its investigation of the probable cause, and its efforts to enhance industry safety. As we did throughout the investigation, Atmos Energy will continue to work collaboratively with the NTSB in response to the Recommendations. Atmos Energy’s commitment to safety is a core value. Our holistic approach to managing safety includes and involves observing, evaluating, and adapting to changing and challenging conditions. We are committed to continuous improvement as we work to achieve our vision of being the safest provider of natural gas service. It is in that spirit that we have continued to assess and strengthen our inside leak investigation procedures in response to fires and explosions when gas involvement cannot be excluded, including those procedures relating to pressure testing and inside gas measurements, as well as the potential need to return to the property after firefighters have departed. The primary objective of Atmos Energy’s emergency response procedures is protecting life, then property. Following the incident on February 23, 2018, Atmos Energy formed a team of experienced operators to review and develop enhanced leak investigation and leak survey procedures. To date, several significant enhancements have been developed and implemented, including the safety initiatives outlined in the Supplement to Atmos Energy Corporation’s Proposed Findings, Probable Cause, and Recommendations to the National Transportation Safety Board dated September 4, 2020. These include, by way of example, the following: • Leak Investigation Procedures o Continuing Actions. If a probable or existing hazardous condition is discovered during the leak investigation, a technician is required to take certain Continuing Actions based on the conditions discovered during the investigation. These actions include: Evacuation of affected structure(s); 911 notification if First Responders are not on-site; Supervisor notification; and Establishment of a Safety Perimeter. o Safety Perimeter. This is an area of restricted entry established when an existing or probable hazardous condition has been identified. The Safety Perimeter is continually monitored and adjusted as conditions change until the potential hazardous condition has been eliminated. When local emergency responders (e.g., fire department) are on site, Atmos Energy personnel are to coordinate the establishment of the Safety Perimeter with the local emergency responders and request assistance with evacuations where appropriate. o Inside leak Investigation. Atmos Energy personnel are to take open-air gas readings prior to entering a structure. If the open-air gas readings at the entranceway are at or above 1%, the Atmos Energy technician does not enter and proceeds with taking Continuing Actions. o Emergency Shutdown and Pressure Reduction. Guidance has been added to the leak investigation procedures in the Service Procedures Manual to clarify and reinforce that: It may be necessary to take prompt actions to control, reduce or eliminate the flow of gas to a location or area, including isolating or shutting down a portion of the gas operating system through the use of valves, regulator or meter stations, squeeze tools, and/or tapping and plugging equipment; Atmos Energy personnel have the authority to initiate a system shutdown without permission; and A supervisor must be notified immediately if the source of gas or odor cannot be located. o Training. After development of these enhanced procedures, Atmos Energy completed training for its emergency responders and operations leaders across all our states. The training also incorporated examples of industry experiences. • Leak Survey Training. Atmos Energy developed and delivered a one-week leak survey refresher training class to all leak survey technicians. The training consisted of classroom instruction, a review of procedures, and hands-on training by equipment vendors. To build upon these previously implemented enhancements, Atmos Energy formed another team of experienced and knowledgeable operators to further consider and incorporate Recommendation P-21-9 relating to inside leak investigations in response to fires and explosions when gas involvement cannot be excluded. While Atmos Energy’s implemented leak investigation procedures (including those in effect in 2018) currently require a pressure test of customer piping on all inside leak investigations when possible, we will incorporate guidance on conducting pressure tests of customer piping in response to fire and explosion calls when natural gas involvement cannot be excluded and when safe to do so. As our experienced operations team completes their development work, any enhancements to the procedures will require a comprehensive training and implementation plan for delivery across our eight-state operation. While the timing of the effort is still under development, we are working toward a goal of completing this by the end of the year and will provide a future update to the NTSB. We will also continue to monitor the work of the Gas Piping Technology Committee (GPTC) in response to Recommendation P-21-13 and consider any additional guidance that is developed related to leak investigations.

Addressee Organization Type: P-Private Industry

Communication Date: 2022-01-11

Communication Type: Official Correspondence

Communication Contents: -From John McDill, Senior Vice President Utility Operations: Atmos Energy submits this letter and attachments to supplement its May 7, 2021 response to the National Transportation Safety Board (NTSB) concerning the NTSB’s January 12, 2021 Report on the incident that occurred in Dallas, Texas on February 23, 2018. As the attached supplemental responses reflect, we have completed our work relative to the NTSB Recommendations P-21-8 through P-21-12. We are committed to continuous improvement on our journey to achieve our vision to be the safest provider of natural gas services. Atmos Energy appreciates the opportunity to have participated in this investigation alongside the NTSB and other party participants to further enhance the safe delivery of natural gas services. Atmos Energy appreciates the opportunity to update the NTSB on the enhancements to our inside leak investigation procedures in response to fires and explosions relating to safety recommendation P-21-9. We remain committed to managing safety and continually improving to achieve our vision of being the safest provider of natural gas service. As outlined in our May 7, 2021 update to the NTSB, following the incident on February 23, 2018, we formed an internal team of experienced operators to review and develop enhanced leak investigation and leak survey procedures that were implemented in 2019. These enhancements included taking Continuing Actions when a probable or existing hazardous condition is discovered, establishing a Safety Perimeter to restrict access and conduct evacuations where appropriate, providing guidance on Emergency Shutdown and Pressure Reduction and reinforcing the authority of personnel to initiate a system shutdown, and developing and rolling out training on these enhancements, including a week-long leak survey refresher for all of our survey technicians. Following issuance of the NTSB’s Final Report in 2021, we reviewed the findings of the report and the safety recommendations with an internal team of experienced and knowledgeable operators. We also leveraged our industry relationships to gather information on the practices of other operators and met with equipment and technology manufacturers. We have now completed this review, developed the appropriate enhancements to fully address the NTSB’s safety recommendations, and provided comprehensive training across our eight-state operation. When responding to a fire-related event, our technicians now have even more rigorous inside leak investigation requirements when gas involvement cannot be excluded, including written guidance on pressure testing and inside gas measurement, and the potential need to return to the property to complete a full leak investigation as appropriate. Specifically, we have updated our procedures to reflect the following new provisions: • Our responding technician will make contact with onsite fire department personnel to determine if any preliminary causes have been determined or excluded, and to notify a Supervisor of any possible gas involvement (regardless of source); • Where appropriate, a Supervisor will follow-up with the fire department if fire department personnel are not on-site to ask if the fire department has determined the cause of the fire-related event; • When natural gas is detected or the involvement of natural gas is suspected, our responding technician will perform a customer piping test using air unless a safety related condition, or other circumstance, prohibits a technician from doing so; • In addition to performing a full leak investigation, our responding technician will also use remote methane leak detection equipment to search for potential gas around, in proximity to, and inside the relevant structure(s) in order to obtain potential gas readings (such as through windows and in crawlspaces without entering the structures) unless a safety related condition or other circumstance prohibits a technician from doing so; and • Our responding technician will contact a supervisor if a full leak investigation cannot be completed to determine a time to return to the site, if appropriate, to complete the investigation. We developed and delivered comprehensive training for operations leaders and technicians (more than 2,200 employees) across our eight-state service territory to support these changes. That effort has been completed and the applicable procedures have been published.

Addressee Organization Type: P-Private Industry

Communication Date: 2021-08-04

Communication Type: Official Correspondence

Communication Contents: In response to our recommendation, you have formed a team of experienced operators to consider and incorporate actions to enhance your inside leak investigations. We note that you are developing further guidance on pressure testing customer piping in response to fire and explosion calls when natural gas involvement cannot be excluded. In cases where doing so is initially unsafe, your guidance will include the need to return to the property after firefighters have departed. Pending your implementation of more rigorous inside leak investigation requirements when gas involvement cannot be excluded, Safety Recommendation P-21-9 is classified OPEN-- ACCEPTABLE RESPONSE.

Addressee Organization Type: P-Private Industry

Communication Date: 2022-05-11

Communication Type: Official Correspondence

Communication Contents: We note that you have developed and implemented more rigorous inside leak investigation requirements in response to fires and explosions when gas involvement cannot be excluded. Your updated procedures require your responding technicians to perform a customer piping test when natural gas is detected or the involvement of natural gas is suspected. In addition to performing a full leak investigation, your responding technician will also use remote methane leak-detection equipment to search for potential gas around, in proximity to, and inside the relevant structures, including crawlspaces, to obtain potential gas readings, unless a safety-related condition or other circumstance prohibits a technician from doing so. Further, your responding technician will contact a supervisor to determine a time to return to the site to complete the investigation if a full leak investigation cannot be completed. These actions satisfy the intent of Safety Recommendation P-21-9, which is classified CLOSED-- ACCEPTABLE ACTION.