NTSB Safety Recommendation P-21-011

NTSB safety recommendation P-21-011.

TO ATMOS ENERGY CORPORATION: 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.

Priority: CLASS II

Overall Status: Closed - Acceptable Action

Issued Date: 2021-02-08

Adopted Date: 2021-01-12

Overall Date Closed: 2023-09-06

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: 2023-09-06

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 leak investigation procedures, including those relating to responding to leaks, fires, and explosions and emergency calls to address the challenges caused by wet weather. 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. Additional work is underway to further consider and incorporate Recommendation P-21-11 relating to responding to leaks, fires, explosions, and emergency calls to address the challenges caused by wet weather conditions. Atmos Energy is currently: • Utilizing our relationships within the industry to gather practices on addressing challenges posed by wet weather. • Meeting with equipment and technology manufacturers to discuss available technologies and the operating parameters of those technologies, potential methods to manage weather related challenges, and equipment/accessory products that could be useful in wet weather. • Conducting an in-depth review of current policies and procedures with an internal team of experienced and knowledgeable operators. We anticipate the outcome of these efforts will be enhanced procedures that include, among other items, expanded areas for investigation and criteria for escalation, including guidance on system shut-in and/or pressuring testing of company facilities when weather conditions prevent a complete leak investigation. 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 leak investigation procedures relating to safety recommendation P-21-1 to address the challenges caused by wet weather conditions when responding to leaks, fires, explosions, and emergency calls. 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. We have revised our policies and procedures for responding to leaks, fires, explosions, and emergency calls to address the challenges caused by wet weather conditions, including (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. Specifically, we have updated our procedures to reflect the following new provisions: • Our responding technician will consider both the extent of environmental conditions encountered and the potential limitations of available gas detection equipment when conducting a leak investigation in weather conditions; • The area of investigation will be expanded to account for other potential migration paths (including other underground utilities) when weather conditions are present; • Our responding technician will contact his or her Supervisor to take Escalated Actions (as explained below) when: (i) weather conditions prevent the completion of the investigation; or (ii) gas has been detected but the source has not been determined; • “Escalated Actions” are required when a leak investigation cannot be completed, or if gas is detected and the source cannot be determined. This requires immediate notification to a Supervisor, and the Supervisor providing additional support to the technician by: (i) bringing additional resources to assist with the investigation, and/or (ii) conducting a special leak survey; • When gas is detected during a leak investigation, but the source cannot be determined, the matter is escalated to a Manager to begin shutting-in or isolating a portion of the system in order to perform a pressure test; and • We have re-emphasized in our procedures and in our training that under any circumstance, Atmos personnel do not need approval to take any and all necessary actions to safeguard life and property, including alternative safe responses such as evacuating occupants and/or shutting-in a portion of the gas operating system. 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: 2023-04-25

Communication Type: Official Correspondence

Communication Contents: -From John McDill, Senior Vice President Utility Operations, Atmos Energy: Atmos Energy submits this letter and attachments to supplement its prior responses 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. The attached supplemental responses reflect the work we have undertaken to implement Recommendations P-21-11 and 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. This addresses the NTSB’s May 11, 2022, request for additional information about items 1 and 3 of Recommendation P-21-11. Item 1: After February 2018, we developed, trained on, and then implemented enhancements to our leak investigation procedures that provide processes and methods for our trained and qualified technicians to apply when performing leak investigations, including wet weather. Those enhancements include, but are not limited to, the following investigation methods: • taking Continuing Actions; • establishing a Safety Perimeter; • contacting 911; • expanding the area of the leak investigation when environmental conditions warrant; • conducting additional testing following fire-related events; • escalating matters to supervisory personnel sooner; and • reemphasizing that technicians have the authority to take prompt actions to control, reduce or eliminate the flow of gas to the location or area. These are significant enhancements that formalize repeatable processes and reliable methods that can be applied to the particulars of any leak investigation, including wet weather, to drive a thorough and effective response. Item 3: With respect to the criteria for shutting-in a portion of the gas operating system, our procedures and our training emphasize that under any circumstance, Atmos personnel do not need approval to take any and all necessary actions to safeguard life and property. The criteria are clear: if a probable or existing hazardous condition is discovered at any time during the leak investigation it may be necessary for a technician to take prompt actions to control, reduce or eliminate the flow of gas to the location or area. Technicians have the authority to take such actions. In addition, if gas is detected during a leak investigation but the source cannot be determined, the matter is escalated to a Manager to begin shutting-in a portion of the system in order to perform a pressure test. The actions described above relating to items 1 and 3 are consistent with industry guide materials. The Gas Piping Technology Committee (GPTC) draft Guide Material and the American Gas Association’s recently published Wet Weather Leak Investigations technical paper were developed in response to the NTSB’s Safety Recommendation P-21-13 which called for additional guidance on “steps gas distribution operators can take to safely respond to leaks, fires, explosions, and emergency calls, considering the limitations due to wet weather conditions…. ” The enhanced methods and procedures that Atmos Energy implemented in 2019 and 2021 (in both our written procedures that were provided to the NTSB’s IIC and our extensive training to over 2,200 employees) are consistent with these materials. Accordingly, we believe we have fully addressed the NTSB’s safety recommendation P-21-11.

Addressee Organization Type: P-Private Industry

Communication Date: 2021-08-04

Communication Type: Official Correspondence

Communication Contents: We note that you are reviewing your policies and procedures for responding to leaks, fires, explosions, and emergency calls to address the challenges caused by wet weather conditions. You are reaching out to other industry experts and meeting with equipment and technology manufacturers to gather information on best practices and methods for investigating leaks in wet weather, including actively monitoring the ongoing work of the Gas Piping Technology Committee. You point out that once this research has been completed and your response policies and procedures have been revised, the enhancements to your leak investigation procedures will require a comprehensive training and implementation plan for delivery across your eight-state operation. Pending the revision of your policies and procedures for responding to leaks, fires, explosions, and emergency calls in wet weather, including training your investigators, Safety Recommendation P 21-11 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 revised your policies and procedures for responding to leaks, fires, explosions, and emergency calls to address the challenges caused by wet weather conditions. We have reviewed your response and believe that your actions have satisfied the second and fourth elements of this recommendation. Further, we believe that having supervisors escalate action when weather conditions prevent a complete investigation, or when gas has been detected but there is uncertainty as to the source, is a positive step. Unfortunately, your response did not indicate the specific changes you have implemented to ensure that your leak investigation methods are reliable in wet weather, nor the new decision criteria you will use to shut down, isolate, or pressure-test distribution system segments if circumstances similar to those existing prior to the fatal Dallas explosion are encountered again in the future. Pending our receipt and evaluation of the specific changes you have made to your leak investigation methods to ensure they are reliable in wet weather and the new criteria you will use to shut down, isolate or pressure-test your system if gas is suspected but weather conditions impede the leak investigation, Safety Recommendation P-21-11 remains classified OPEN-- ACCEPTABLE ACTION.

Addressee Organization Type: P-Private Industry

Communication Date: 2023-09-06

Communication Type: Official Correspondence

Communication Contents: Following your previous response on January 11, 2022, we asked you for further clarification on how you revised your policies and procedures to include leak investigation methods that are reliable in wet weather and to ensure an alternate safe response, such as evacuation, when reliable investigations are not possible due to wet weather or other circumstances. We note that you consulted with industry experts and equipment and technology manufacturers to determine best practices and equipment capabilities and limitations for conducting gas leak surveys in wet weather. You report that your revised policies and procedures for responding to leaks have incorporated the lessons learned from the Dallas event and are consistent with the American Gas Association’s Wet Weather Leak Investigations white paper, published in January 2023, and the Gas Pipeline Technical Committee’s draft guidelines on gas leak detection procedures for wet weather. Accordingly, Safety Recommendation P 21-11 is classified CLOSED-- ACCEPTABLE ACTION.