NTSB Safety Recommendation Letter P-22-001 through P-22-006

Page 1Official PDFSeptember 14, 2022 The Honorable Tristan Brown Deputy Administrator Pipeline and Hazardous Materials Safety Administration The attached letter from the NTSB Chair provides information about the NTSB’s August 15, 2022, report Enbridge Inc. Natural Gas Transmission Pipeline Rupture and Fire, Danville, Kentucky, August 1, 2019, NTSB/PIR- 22/02. 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. 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-22-1 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. Executive Secretariat-CRB Office of the Managing Director National Transportation Safety Board 490 L’Enfant Plaza SW Washington, DC 20594 Email: ExecutiveSecretariat@ntsb.gov#

Page 2National Transportation Safety Board Office of the Chair Washington, DC 20594 September 14, 2022 The Honorable Tristan Brown Deputy Administrator Pipeline and Hazardous Materials Safety Administration US Department of Transportation 1200 New Jersey Avenue, SE Washington, DC 20590 Dear Mr. Brown: This letter provides information about the National Transportation Safety Board’s (NTSB) August 15, 2022, report Enbridge Inc. Natural Gas Transmission Pipeline Rupture and Fire, Danville, Kentucky, August 1, 2019, NTSB/PIR-22/02. 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: • Nonconservative assumptions used to calculate potential impact radius. • Incomplete evaluation of the risks caused by a change of gas flow direction. • Limitations in data analysis related to the 2011 in-line inspection. • Operators’ potential for incomplete assessment of threats and threat interactions. • Missed opportunities in training and requalification practices at Enbridge. Accordingly, the NTSB makes the following safety recommendations to the Pipeline and Hazardous Materials Safety Administration. Additional information regarding these recommendations can be found in the noted sections of the report. • Revise the calculation methodology used in your regulations to determine the potential impact radius of a pipeline rupture based on the accident data and human response data discussed in this report. (P-22-1) (See section 2.3) [68419]#

Page 32 • Advise natural gas transmission pipeline operators on (a) the circumstances of this accident; (b) the need to evaluate the risks associated with flow reversal projects; and (c) the impacts of such projects on hydrogen-induced cracking. (P- 22-2) (See section 2.4) • Advise natural gas transmission pipeline operators of the possible data limitations associated with hard spot magnetic flux leakage in-line inspection tools and analyses used in hard spot management programs and reinforce the need to follow industry best practices when conducting in-line inspection data analysis. (P-22-3) (See section 2.5) 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 Recommendations P-22-1, -2 and -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 on how to send larger documents. Please do not submit both an electronic copy and a hard copy of the same response. Sincerely, [Original Signed] Jennifer Homendy Chair#

Page 4September 14, 2022 Mr. Al Monaco President and Chief Executive Officer Enbridge Inc. 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 Chair provides information about the NTSB’s August 15, 2022, report Enbridge Inc. Natural Gas Transmission Pipeline Rupture and Fire, Danville, Kentucky, August 1, 2019, NTSB/PIR-22/02. 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-22-4 through -6).#

Page 5National Transportation Safety Board Office of the Chair Washington, DC 20594 September 14, 2022 Mr. Al Monaco President and Chief Executive Officer Enbridge Inc. 200, 425 – 1st Street SW Calgary, AB T2P 3L8 Canada Dear Mr. Monaco: 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 Enbridge Inc., to act on the safety recommendations 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 also includes information about our August 15, 2022, report Enbridge Inc. Natural Gas Transmission Pipeline Rupture and Fire, Danville, Kentucky, August 1, 2019, NTSB/PIR-22/02. 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: • Nonconservative assumptions used to calculate potential impact radius. • Incomplete evaluation of the risks caused by a change of gas flow direction. • Limitations in data analysis related to the 2011 in-line inspection. • Operators’ potential for incomplete assessment of threats and threat interactions. • Missed opportunities in training and requalification practices at Enbridge, Inc. [68419]#

Page 62 Accordingly, the NTSB makes the following safety recommendations to Enbridge, Inc. Additional information regarding these recommendations can be found in the noted section of the report. • Evaluate the effectiveness of your corrosion control equipment and infrastructure following any major change in operations, such as a gas flow reversal. (P-22-4) (See section 2.4) • Revise your integrity management program to include (a) data required to support the active or inactive status of each threat, including hard spots; (b) conditions and situations that require reassessment and re-evaluation of threat status, including flow reversal and other major projects; and (c) the interactions between hard spots and all types of corrosion. (P-22-5) (See section 2.6) • Disqualify and require remedial training and requalification of the covered task(s) whenever an employee does not follow procedures when responding to an emergency shutdown, rupture, or other abnormal operation. (P-22-6) (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 Recommendations P-22-4, -5 and -6). 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 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 are stored by the NTSB and viewable by the public. Please do not send privileged or confidential communications in response to these recommendations. Responses marked as confidential or privileged (or similar designations) will be considered nonresponsive. In the likely event that your company uses auto-generated and/or preformatted confidentiality statements on letterhead or outgoing e-mails, please include a statement in your letter indicating that the information can be publicly released. If you have concerns about this protocol, please contact us at ExecutiveSecretariat@ntsb.gov.#

Page 7Sincerely, [Original Signed] Jennifer Homendy Chair 3#

Page 8NTSB Recommendations and You The National Transportation Safety Board (NTSB) is an independent federal agency charged with investigating and determining the probable cause of transportation accidents. We do not make regulations, but we do issue recommendations to organizations such as yours when we discover shortcomings in the transportation system that increase the risk of accidents. As a result of our investigative activities, we have issued one or more safety recommendations that we believe you can act on to improve transportation safety. Why did the NTSB issue my organization a safety recommendation? We issue safety recommendations to organizations that can bring about change to reduce the risk of accidents, either through their direct role in the transportation industry, their legislative or regulatory authority, or the significant influence they have among others in the industry. We believe your organization is able to make or influence such changes. What does the NTSB expect of safety recommendation recipients? First and foremost, we encourage you to promptly take the recommended action to improve safety. Because we’re eager to see recommendations implemented before more accidents occur, we follow recipients’ efforts to implement each recommendation. We ask that you update us any time you achieve a significant milestone in your progress toward implementing the attached recommendation(s), or at least annually. We will provide feedback on your efforts by classifying each recommendation as open or closed, acceptable or unacceptable.1 Information about your actions associated with your recommendation(s) is available at our website so that the public can see our combined efforts to improve transportation safety. What should our response to the NTSB include? Please respond to us within 90 days (30 for urgent recommendations) explaining the specific actions you have taken or intend to take in response to the safety recommendation(s), and propose a timeline for completion. We understand organizations today are faced with competing priorities and limited resources, which can make implementing our recommendations a challenge. If, for any reason, you are not able to take the recommended action, or if you believe an alternate action would be more appropriate for your organization, please explain why. When you respond, please provide an e-mail address for future communications. We will review your response and provide feedback. What if my organization doesn’t believe the recommended action is the best way to improve safety? We base our recommendations on the evidence, facts, and circumstances of the accidents we investigate. Sometimes industry leaders identify ways to attain the same safety objective more efficiently, and we encourage recipients to share their ideas with us. In these cases, we will evaluate the alternate means of achieving the safety objective and provide feedback. We believe safety is a collaborative effort, and we’re happy to work with your organization to set goals and make improvements. Why does the NTSB expect us to take action, even though our organization wasn’t responsible for the accident that resulted in the safety recommendation? Our goal is to prevent accidents. Often, the factors we identify as causing or contributing to an accident are not unique— they represent common practices or situations that may be accidents waiting to happen. In such instances, we may make recommendations intended to raise the minimum standard for safety throughout the industry. How do we contact the NTSB to provide updates or obtain further information? Please contact us electronically at executivesecretariat@ntsb.gov. If you wish to send us supporting documentation that, with your response, exceeds 10 megabytes, please contact us at the same e-mail address for instructions. 1  For a full description of our safety recommendation classifications, see the Status Explanation page on our website. www.ntsb.gov We look forward to working with you to prevent accidents and save lives!#