# NTSB Safety Recommendation P-21-001

- **operation:** document
- **citation:** P-21-001
- **title:** NTSB Safety Recommendation P-21-001
- **source type:** guidance
- **agency:** National Transportation Safety Board
- **status:** guidance
- **official:** true
- **published on:** 2021-02-08
- **effective on:** 2021-02-08
- **summary:** TO PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION: Expand incident reporting requirements in Title 49 Code of Federal Regulations Part 191 so that events that may meet the definition of “incident” are immediately reported to the National Response Center even when the source of the natural gas has not been determined.
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**body:**

NTSB safety recommendation P-21-001.

TO PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION: Expand incident reporting requirements in Title 49 Code of Federal Regulations Part 191 so that events that may meet the definition of “incident” are immediately reported to the National Response Center even when the source of the natural gas has not been determined.

Priority: CLASS II

Overall Status: Open Acceptable Alternate Response

Issued Date: 2021-02-08

Adopted Date: 2021-01-12

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: PHMSA

Addressee Status: Open Acceptable Alternate Response

Addressee Acronym: PHMSA

Addressee Organization Type: G-Federal Government

Communication Date: 2021-02-08

Communication Type: Transmittal Letter

Communication Contents: 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 recommendations may be found in the attached report, which can also be accessed at http://www.ntsb.gov. 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 recommendations by number (for example, P 21-1 through -3). 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. 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 Energy Corporation (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 PHMSA. Additional information regarding these recommendations can be found in the noted sections of the report. • Expand incident reporting requirements in Title 49 Code of Federal Regulations Part 191 so that events that may meet the definition of “incident” are immediately reported to the National Response Center even when the source of the natural gas has not been determined. (P 21-1) (See section 2.6.1.) • Evaluate industry’s implementation of the gas distribution pipeline integrity management requirements and develop updated guidance for improving their effectiveness. The evaluation should specifically consider factors that may increase the likelihood of failure such as age, increase the overall risk (including factors that simultaneously increase the likelihood and consequence of failure), and limit the effectiveness of leak management programs. (P 21-2) (See section 2.7.) • Assist the Railroad Commission of Texas in conducting the audit recommended in Safety Recommendation P-21-4. (P-21-3) (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 recommendations by number (Safety Recommendation(s) P-21-1 through -3). We encourage you to submit your response to ExecutiveSecretariat@ntsb.gov. If your reply, including attachments, exceeds 20 megabytes, please e mail us at the same address for instructions. Please do not submit both an electronic copy and a hard copy of the same response.

Addressee Acronym: PHMSA

Addressee Organization Type: G-Federal Government

Communication Date: 2021-07-16

Communication Type: Official Correspondence

Communication Contents: You point out that PHMSA’s regulations already require operators to notify the NRC of each “incident,” even when the operator has not determined with certainty that its pipeline was the source of natural gas. Further, you reported that, during calendar years 2018 through 2020, PHMSA received and reviewed an average of 26,400 reports annually from the NRC and determined that approximately 97.5 percent of these incidents were nonjurisdictional or from nonregulated entities; therefore, you believe that expanding incident reporting requirements as we recommended will significantly increase the number of false alarms PHMSA and the states receive because of overreporting. As a result, you proposed several alternative actions to augment existing regulatory reporting requirements and address this recommendation. We note that you plan to issue an advisory bulletin (ADB) reminding pipeline operators to promptly report incidents based on available information, even if they have only conducted a preliminary evaluation. The ADB will list relevant conditions for determining if an incident should be reported to the NRC, such as rupture or explosion, fire, loss of service, evacuation of people in the area, and involvement of local emergency response personnel, and will also emphasize that operators must consider a pipeline’s historic performance and risks to the public in the area. Further, PHMSA will use regional and national meetings of the National Association of Pipeline Safety Representatives to stress the importance of timely and accurate reporting, and will continue to evaluate industry’s incident reporting performance. You will submit your evaluation findings to us within 1 year after the ADB is issued. Although you indicated that there is not a systemic nationwide failure in incident reporting, the provided analysis neither supports nor refutes this claim. NRC reports cover a much broader scope than PHMSA’s, so the majority of NRC reports are from entities outside PHMSA’s jurisdiction or that PHMSA does not regulate; this analysis, then, is not an indication of the number of false alarms associated with reports by natural gas pipeline operators. Further, if operators are reporting incidents based on preliminary information, as required, some incidents will later be determined not to be regulated by PHMSA. Because these scenarios are expected, they are not accurately described as overreporting or false alarms. We believe your proposed ADB may satisfy the intent of our safety recommendation, provided the following: • It clearly states that operators are required to provide immediate notification of possible incidents, even when the source of natural gas has not been determined, so emergency personnel and investigators can be dispatched quickly. • It provides examples of scenarios that require immediate notification of possible incidents even when the source of natural gas has not been determined. • It clearly indicates that operators do not have any additional time (beyond the 1 hour immediate notification requirement) to evaluate whether their facilities can be positively excluded from having contributed to an incident before they are required to provide immediate notification. • PHMSA can accurately assess its effectiveness. Pending our review of the issued ADB containing this information and data showing that it is effective, Safety Recommendation P 21-1 is classified OPEN-- ACCEPTABLE ALTERNATE RESPONSE.

Addressee Acronym: PHMSA

Addressee Organization Type: G-Federal Government

Communication Date: 2022-05-02

Communication Type: Official Correspondence

Communication Contents: In our July 16, 2021, response to your May 3, 2021, letter about these recommendations, we classified Safety Recommendation P-21-1 OPEN-- ACCEPTABLE ALTERNATE RESPONSE and Safety Recommendations P-21-2 and -3 “Open—Acceptable Response.”

Addressee Acronym: PHMSA

Addressee Organization Type: G-Federal Government

Communication Date: 2022-01-14

Communication Type: Official Correspondence

Communication Contents: -From Tristan H. Brown, Deputy Administrator: PHMSA provided NTSB with an alternate response for this recommendation on May 3, 2021, and looks forward to NTSB accepting our response.

Addressee Acronym: PHMSA

Addressee Organization Type: G-Federal Government

Communication Date: 2021-05-03

Communication Type: Official Correspondence

Communication Contents: -From Tristan Brown, Acting Administrator: PHMSA proposes NTSB consider alternative actions to address this recommendation. PHMSA’s regulations already require operators to notify the National Response Center (NRC) of each “incident” (as defined in 49 C.F.R. § 191.3) even when the operator has not determined with certainty that its pipeline was the source of natural gas (§ 191.5(a)). Specifically, § 191.5(a) requires an operator to give notice of an incident at the earliest practicable moment, but no later than one hour after “confirmed discovery.” “Confirmed discovery” is defined in § 191.3 as “when it can be reasonably determined, based on information available to the operator at the time [that] a reportable event has occurred, even if only based on a preliminary evaluation.” PHMSA examined historical incident reports from natural gas and hazardous liquid pipeline operators for calendar years 2018 – 2020. Based on this data, annually, PHMSA received and reviewed an average of 26,400 reports from the NRC. Approximately 97.5% of these incidents were determined to be non-jurisdictional or from non-regulated entities. Expanding incident reporting requirements to mandate that operators report even more “possible incidents” will significantly increase the number of “false alarms” received by PHMSA and the states due to overreporting. NTSB’s report identified, among other things, a deficiency in Atmos’ incident response procedures and compliance with PHMSA’s regulations. Because PHMSA recognizes the important role adequate and accurate reporting of incidents plays in helping to prevent incidents like the Dallas, Texas, accident, we believe that the safety intent of recommendation P-21-01 can be best achieved through the following actions to augment the existing regulatory reporting requirements: Issue an advisory bulletin (ADB) reminding pipeline operators to promptly report incidents based on available information, even if only a preliminary evaluation has been conducted. The ADB will highlight the regulatory requirements and associated definitions of “incident” and “confirmed discovery.” Furthermore, the ADB will state that the following conditions, identified by NTSB, are relevant when operators evaluate an event to determine if it should be reported to the NRC as a possible incident: rupture or explosion, fire, loss of service, evacuation of people in the area, and involvement of local emergency response personnel when evaluating a reportable incident. PHMSA will also note that operators must consider the historic performance of pipelines and the safety concerns of the public in proximity to the location of the event in their evaluation. PHMSA will review the findings of the NTSB report at upcoming National Association of Pipeline Safety Regulators (NAPSR) Regional and National meetings. PHMSA will stress the importance of timely and accurate reporting of incidents involving gas pipeline distribution systems and will review this data during our annual evaluations of states’ pipeline safety programs. PHMSA will continuing to monitor NRC/30-day incident reports to evaluate industry’s reporting performance and submit our findings to NTSB within one year after the issuance of the ADB.
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