NTSB Safety Recommendation P-19-015

NTSB safety recommendation P-19-015.

TO THE PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION: Issue an alert to all low-pressure natural gas distribution system operators of the possibility of a failure of overpressure protection; and the alert should recommend that operators use a failure modes and effects analysis or equivalent structured and systematic method to identify potential failures and take action to mitigate those identified failures.

Priority: CLASS II

Overall Status: Closed - Acceptable Action

Issued Date: 2019-10-24

Adopted Date: 2019-09-24

Overall Date Closed: 2021-04-19

Synopsis: On September 13, 2018, about 4:00 p.m. local time, a series of structure fires and explosions occurred after high-pressure natural gas was released into a low-pressure natural gas distribution system in the northeast region of the Merrimack Valley in the Commonwealth of Massachusetts. The natural gas distribution system was owned and operated by Columbia Gas of Massachusetts, a subsidiary of NiSource, Inc. Columbia Gas of Massachusetts delivers natural gas to about 325,000 customers in Massachusetts. One person was killed and 22 individuals, including three firefighters, were transported to local hospitals due to injuries; seven other firefighters incurred minor injuries. The fires and explosions damaged 131 structures, including at least 5 homes that were destroyed in the city of Lawrence and the towns of Andover and North Andover. Most of the damage occurred from fires ignited by natural gas-fueled appliances; several of the homes were destroyed by natural gas-fueled explosions. Fire departments from the three municipalities were dispatched to the fires and explosions. First responders initiated the Massachusetts fire-mobilization plan and received mutual aid from neighboring districts in Massachusetts, New Hampshire, and Maine. Emergency management officials had the electric utility shut down electrical power in the area, the state police closed local roads, and freight and passenger railroad operations in the area were suspended. Columbia Gas of Massachusetts shut down the low-pressure natural gas distribution system, affecting 10,894 customers, including some outside the area who had their service shut off as a precaution. The National Transportation Safety Board made new recommendations to the Pipeline and Hazardous Materials Safety Administration; the 31 states with an industrial exemption for natural gas infrastructure projects; the Commonwealth of Massachusetts Executive Office of Public Safety and Security; and NiSource, Inc.

Probable Cause: The National Transportation Safety Board determines that the probable cause of the overpressurization of the natural gas distribution system and the resulting fires and explosions was Columbia Gas of Massachusetts’ weak engineering management that did not adequately plan, review, sequence, and oversee the construction project that led to the abandonment of a cast iron main without first relocating regulator sensing lines to the new polyethylene main. Contributing to the accident was a low-pressure natural gas distribution system designed and operated without adequate overpressure protection.

Keywords: Hazmat

Ntsbnumber: PLD18MR003

Report Number: PAR-19-02

Addressee Name: PHMSA

Addressee Status: Closed - Acceptable Action

Addressee Date Closed: 2021-04-19

Addressee Acronym: PHMSA

Addressee Organization Type: G-Federal Government

Communication Date: 2019-10-24

Communication Type: Transmittal Letter

Communication Contents: The attached letter from the NTSB Chairman provides information about the NTSB’s September 24, 2019, report Overpressurization of Natural Gas Distribution System, Explosions, and Fires in Merrimack Valley, Massachusetts, September 13, 2018, NTSB/PAR-19/02. 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. 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-19-14 and -15). 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) September 24, 2019, report Overpressurization of Natural Gas Distribution System, Explosions, and Fires in Merrimack Valley, Massachusetts, September 13, 2018, NTSB/PAR-19/02. 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: • Adequacy of natural gas regulations • Project documentation • Constructability review • Project management • Risk assessment • Safety management systems • Licensed professional engineer approval of natural gas projects • Emergency response 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 Title 49 Code of Federal Regulations Part 192 to require overpressure protection for low-pressure natural gas distribution systems that cannot be defeated by a single operator error or equipment failure. (P-19-14) (See section 3.2.) • Issue an alert to all low-pressure natural gas distribution system operators of the possibility of a failure of overpressure protection; and the alert should recommend that operators use a failure modes and effects analysis or equivalent structured and systematic method to identify potential failures and take action to mitigate those identified failures. (P-19-15) (See section 3.2.) 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-19-14). 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: 2023-10-27

Communication Type: NPRM Response

Communication Contents: The National Transportation Safety Board (NTSB) has reviewed the Pipeline and Hazardous Materials Safety Administration’s (PHMSA) notice of proposed rulemaking (NPRM), titled “Pipeline Safety: Safety of Gas Distribution Pipelines and Other Pipeline Safety Initiatives,” published at 88 Federal Register 61746 on September 7, 2023. The NPRM proposes amendments to Title 49 Code of Federal Regulations (CFR) Parts 191, 192, and 198 in response to congressional mandates in the Leonel Rondon Pipeline Safety Act and an NTSB safety recommendation aimed at preventing catastrophic incidents resulting from overpressurization of low pressure gas distribution systems. The NTSB investigated two natural gas accidents that resulted in recommendations that are applicable to this NPRM. We describe these investigations and offer comments on the following topic areas: Clarifications and Updates to Distribution Integrity Management Program Plans, Updates to Emergency Response Communications, Updates to Operations and Maintenance Procedural Manuals, and Requirements for New Regulator Stations. Related NTSB Investigations In February 2018, the NTSB investigated a natural gas fueled explosion in Dallas, Texas, which resulted in 1 fatality; 4 injuries; a destroyed home; and the evacuation of 300 homes, 250 apartment units, and 600 students. In the 2 days before the explosion, two gas related incidents occurred on the same block at houses that were served by the same natural gas main, each resulting in one injury and significant structural damage. We determined that the probable cause of the accident was the ignition of natural gas that leaked from a gas main that was damaged 23 years earlier and was undetected by the operator’s investigation of the two related incidents that occurred in the 2 days before the explosion. In September 2018, the NTSB investigated the overpressurization of a natural gas distribution system in Merrimack Valley, Massachusetts, which resulted in fires and explosions, 1 fatality, 22 individuals being taken to local hospitals, 5 destroyed homes, 131 damaged structures, and the evacuation of 50,000 residents. We determined that the probable cause of the accident was the operator’s failure to adequately plan, review, sequence, and oversee a pipeline construction project. Clarifications and Updates to Distribution Integrity Management Program Plans NPRM Commentary In the NPRM, PHMSA proposes requiring that operators identify and minimize the risks to their systems from specific threats in their distribution integrity management program plans, such as (1) the presence of certain materials, like cast iron and other piping with known issues; (2) overpressurization of low pressure systems; and (3) extreme weather and other geohazards. PHMSA also proposes that operators consider the effect of age on those specific threats faced by a distribution pipeline. In addition, the NPRM proposes that, for operators of low pressure gas distribution systems, when evaluating and ranking risks, operators must also consider (1) the configuration of their overpressure protection, (2) the availability of gas pressure monitoring, and (3) the likelihood of any single event that could result in an overpressurization. NTSB Comment The NTSB’s investigations into both the Dallas and Merrimack Valley accidents demonstrate the importance of operators appropriately evaluating and mitigating risks to their pipeline systems. In our Dallas investigation, we determined that the operator’s inadequate integrity management program contributed to the degradation of the pipeline system. We noted that the operator did not adequately consider or mitigate against threats that were degrading its pipeline system, the likelihood of failure associated with these threats, or the potential consequences of such a failure as required by gas distribution integrity management rules. In addition, we concluded that while the operator’s periodic leak survey methodology and frequency complied with the minimum state and federal requirements, it did not identify the pipeline system degradation that authorities found after the accident. As a result, we recommended that PHMSA: 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) In our Merrimack Valley investigation, we determined that a comprehensive and formal risk assessment would have identified the human error that caused the redundant regulators to open and overpressurize the system. As a result, we issued Safety Recommendation P 19 15 to PHMSA to issue an alert to operators of low pressure natural gas distribution systems notifying them of the possibility of a failure of overpressure protection and recommending that they use a failure modes and effects analysis or equivalent method to identify potential failures and take action to mitigate those failures. After PHMSA issued an advisory bulletin, titled “Overpressure Protection on Low Pressure Natural Gas Distribution Systems,” we classified the recommendation as Closed—Acceptable Action. The NTSB supports PHMSA’s proposal to add more stringent risk management requirements to distribution integrity management program plans. We also understand that PHMSA is still evaluating gas distribution pipeline integrity management requirements to develop the recommended guidance for improving their effectiveness, two components necessary to fully satisfy Safety Recommendation P 21 2. Summary The NTSB supports many of the NPRM’s proposed revisions to its pipeline safety regulations. However, we believe that the proposal has some shortcomings and encourage PHMSA to address our comments in its final rulemaking. Thank you for the opportunity to comment on this notice.

Addressee Acronym: PHMSA

Addressee Organization Type: G-Federal Government

Communication Date: 2020-07-31

Communication Type: Official Correspondence

Communication Contents: We note that you intend to issue an advisory bulletin (ADB) alerting all operators of low-pressure natural gas distribution systems of the high risk of overpressure protection failure, and reminding them to consider that risk in their distribution integrity management programs (DIMPs). Additionally, you will recommend that operators enhance processes and procedures to include failure modes and effects analysis, or equivalent structured and systematic methods, to identify and mitigate possible overpressure failure events. Finally, you will urge operators to develop and implement procedures for construction-related work specific to low-pressure distribution systems, such as repairs, pressure uprates, or replacement of pipeline or pressure regulation facilities. In our report on the Merrimack Valley incident, we pointed out that we have investigated at least six pipeline accidents in which a single-mode failure resulted in high pressure gas being introduced into a low-pressure gas distribution system. Although current regulations require operators to consider all risks in their DIMPs, we believe it is important to explicitly require operators to address the risk of overpressurization in low pressure distribution systems. In addition to procedures, we suggest that you require operators to develop checklists for construction-related work on low-pressure distribution systems. We note that, in April 2020, you updated sections D4 and D5 of the Pipeline Safety-Gas and Hazardous Liquid State Program Evaluation Evaluator Guidance to include a question verifying that state regulators are asking operators about the safe operation of their low-pressure gas distribution pipeline systems and about the use of failure modes and effects analysis, or equivalent structured and systematic methods, to identify and mitigate potential failures in their low-pressure gas distribution pipeline systems. Further, we note that you plan to issue the ADB by spring 2021. Pending issuance of the ADB, Safety Recommendation P-19-15 is classified OPEN--ACCEPTABLE RESPONSE.

Addressee Acronym: PHMSA

Addressee Organization Type: G-Federal Government

Communication Date: 2021-04-19

Communication Type: Official Correspondence

Communication Contents: We note that PHMSA issued an advisory bulletin (AB), “Overpressure Protection on Low Pressure Natural Gas Distribution Systems,” on September 29, 2020, which describes the details of the Merrimack Valley, Massachusetts, overpressurization incident and our findings and recommendations. PHMSA reminded natural gas distribution system operators that overpressure protection may fail, and recommended that operators use a failure-modes-and-effects analysis to identify potential failures and to take action to mitigate them. Accordingly, Safety Recommendation M-19-15 is classified CLOSED-- ACCEPTBLE ACTION.

Addressee Acronym: PHMSA

Addressee Organization Type: G-Federal Government

Communication Date: 2020-01-22

Communication Type: Official Correspondence

Communication Contents: -From Howard R. Elliott, Administrator: The mission of PHMSA is to protect people and the environment by advancing the safe transportation of energy and other hazardous materials that are essential to our daily lives. PHMSA shares NTSB's commitment to preventing pipeline accidents and has a long history of cooperating and collaborating with NTSB. PHMSA recognizes the important role overpressure protection plays in preventing accidents like the Merrimack Valley incident and agrees that over-pressurization of low-pressure distribution systems must be considered a threat. PHMSA' s regulations already require operators to account for all existing and potential threats, including over-pressurization of low-pressure distribution systems (if they have any), in their Distribution Integrity Management Program (DIMP; 49 CFR Part 192, Subpart P). Specifically, Subpart P requires operators to have and implement a plan that, among other things, must identify existing and potential threats to their system, evaluate and rank the risk assessment with this system, identify and implement measures to address the risks, and develop and evaluate the performance of their DIMP. PHMSA is prohibited by statute, however, from issuing retroactive design and construction standards. Specifically, 49 U.S.C. § 60104(b) states: "[A] design, installation, construction, initial inspection, or initial testing standard does not apply to a pipeline facility existing when the standard is adopted." While PHMSA may not issue retroactive design and construction standards, PHMSA believes we can achieve the intent of both NTSB Recommendations by implementing the following alternative actions: • Consider requirements for overpressure protection for low-pressure gas distribution systems that cannot be defeated by a single operator error or equipment failure for pressure reduction stations that serve such systems and that are newly constructed, replaced, relocated, or substantially altered. • Issue an Advisory Bulletin (ADB) alerting all low-pressure natural gas distribution system operators that PHMSA considers the possibility of overpressure protection failure to be a high-risk threat and reminding them that this risk must be considered in their DIMP. PHMSA will recommend operators enhance processes and procedures to include the failure modes and effects analysis, or equivalent structured and systematic methods, to identify and mitigate possible overpressure failure events. PHMSA will also urge operators to develop and implement procedures for construction-related work specific to low-pressure distribution systems, such as repairs, uprates in pressure, or replacement of pipeline or pressure regulation facilities. • Modify PHMSA's State Program Evaluation Form to include a question verifying that state regulators are asking operators about the safe operation of their low-pressure gas distribution pipeline systems to ensure their use of failure modes and effects analysis, or equivalent structured and systematic methods, to identify and mitigate potential failures. PHMSA plans to complete a policy analysis to assess the feasibility of new requirements by Fall 2020. PHMSA plans to modify the State Program Evaluation Form by Spring 2020, and issue the ADB by Spring 2021. PHMSA is committed to continuously help improve the safety of our nation's pipeline system. Toward that end, we take our responsibility to address all NTSB recommendations seriously. PHMSA is requesting that NTSB accept our alternative actions to address the intent of Recommendations P-19-14 and P-19-15. My staff and I would be pleased to meet with you to further discuss this proposal. We look forward to a favorable response.

Addressee Acronym: PHMSA

Addressee Organization Type: G-Federal Government

Communication Date: 2020-12-21

Communication Type: Official Correspondence

Communication Contents: -From Howard R. Elliott, Administrator: PHMSA proposes closure of this recommendation. In September 2020, PHMSA issued an Advisory Bulletin (ADB) reminding owners and operators of natural gas distribution pipelines of the possibility of failure due to an overpressurization on low-pressure distribution systems.2 The ADB also reminds owners and operators of existing Federal integrity management regulations for gas distribution systems. PHMSA's existing integrity management regulations require operators to account for all existing and potential threats, including overpressurization of low-pressure distribution systems (if they have any), in their Distribution Integrity Management Program (DIMP; 49 CFR Part 192, Subpart P). Specifically, Subpart P requires operators to have and implement a plan that, among other things, must identify existing and potential threats to their systems, evaluate and rank the risks within their systems, identify and implement measures to address the risks, and develop and evaluate the performance of their DIMP.

Addressee Acronym: PHMSA

Addressee Organization Type: G-Federal Government

Communication Date: 2019-12-03

Communication Type: Official Correspondence

Communication Contents: -From Howard R. Elliott, Administrator: PHMSA is reviewing this recommendation and plans to send a response within the 90-days allowed by NTSB.