NTSB Safety Recommendation P-19-014

NTSB safety recommendation P-19-014.

TO THE PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION: 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.

Priority: CLASS II

Overall Status: Open - Acceptable Response

Issued Date: 2019-10-24

Adopted Date: 2019-09-24

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: Open - Acceptable Response

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. Requirements for New Regulator Stations NPRM Commentary In the NPRM, PHMSA proposes to require that (1) operators equip all new, replaced, relocated, or otherwise changed district regulator stations serving low pressure gas distribution systems with at least two methods of overpressure protection; (2) operators minimize the risks from an overpressurization of a low pressure system caused by a single event; and (3) operators of low pressure gas distribution systems monitor the outlet gas pressure at or near the district regulator station on such systems using a device capable of providing real time overpressurization notification to the operator. NTSB Comment Our Merrimack Valley investigation demonstrates the importance of overpressure protection in low-pressure gas distribution systems. We identified that the operator’s low pressure natural gas distribution system was designed and operated without adequate overpressure protection and that this contributed to the accident. The Merrimack Valley accident was not an isolated event. In the 50 years before, we had investigated seven overpressurization accidents that had a collective impact of 4 fatalities, 25 injuries, and 258 damaged or destroyed properties. Our investigation concluded that low pressure natural gas distribution systems that use only sensing lines and regulators as the means to detect and prevent overpressurization are not optimal to prevent overpressurization accidents. As a result, we recommended that PHMSA: 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) In correspondence with us, PHMSA stated that it cannot require changes to existing systems because, under 49 U.S. Code 60104(b), it does not have the authority to issue retroactive design and construction standards. We disagree with PHMSA’s view that it does not have the authority to require changes for existing systems. In October 2019, PHMSA amended Subpart M of 49 CFR Part 192.750 to require operators to equip existing, in service launchers and receivers with a device to ensure that pressure was safely relieved. The agency should reconsider whether revising a part of the regulation that can be applied retroactively is a reasonable option for requiring operators to provide overpressurization protection for existing regulator stations. The NTSB believes that the NPRM’s proposed requirements for new regulator stations, while likely to improve the safety of low pressure gas distribution systems, would not have prevented or mitigated the explosions and natural gas-fueled fires in the Merrimack Valley accident because the proposal does not call for changes to existing regulator stations. Consequently, these requirements would not satisfy Safety Recommendation P 19 14. We urge PHMSA to require that the proposed overpressurization protections apply to all new and existing regulator stations. 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 recognize the importance of overpressure protection in preventing accidents like the one in the Merrimack Valley, and you agree that overpressurization of low pressure distribution systems must be considered a high-risk threat. We believe you may have misinterpreted the intent of our recommendation, which is similar to others that we have previously issued to address safety concerns with existing pipelines. To be clear, to satisfy this recommendation, you do not have to require that existing low-pressure gas distribution systems be completely redesigned; rather, you may satisfy it by adding additional protections, such as slam-shut or relief valves, to existing district regulator stations or other appropriate locations in the system. Although they are a step in the right direction, your proposed alternate actions alone will not address the safety of existing low pressure gas distribution systems and the safety deficiencies identified by our investigation. Pending action to satisfy Safety Recommendation P 19-14, it is classified OPEN--UNACCEPTABLE RESPONSE.

Addressee Acronym: PHMSA

Addressee Organization Type: G-Federal Government

Communication Date: 2022-05-02

Communication Type: Official Correspondence

Communication Contents: In its January 22, 2020, response to this recommendation, PHMSA said that Title 49 United States Code section 60104(b) prohibited it from issuing retroactive design and construction standards. However, although PHMSA said it could not issue retroactive design and construction standards, several alternative actions were proposed that PHMSA believed could achieve the intent of the recommendation. When we replied on July 31, 2020, we clarified that to satisfy this recommendation, you do not have to require that existing low-pressure gas distribution systems be completely redesigned; rather, you may satisfy the recommendation by adding additional protections, such as slam-shut or relief valves, to existing district regulator stations or other appropriate locations in the system. Although the alternative actions proposed were a step in the right direction, they alone would not address the safety of existing low pressure gas distribution systems and the safety deficiencies identified by our investigation. We note from your current letter that the PIPES Act of 2020 requires PHMSA to promulgate regulations to ensure that operators adequately address overpressurization events and common modes of failure. We further note that you plan to address this safety issue in an NPRM, titled “Pipeline Safety: Safety of Gas Distribution Pipelines.” This future rulemaking, in conjunction with the alternative actions that you previously proposed may satisfy the intent of our recommendation to require overpressure protection for low-pressure natural gas distribution systems that cannot be defeated by a single operator error or equipment failure. Pending the completion and our evaluation of these actions, Safety Recommendation P-19-14 is classified 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 requests NTSB change the status of this recommendation to Open—Acceptable Response. NTSB’s July 31, 2020, letter stated that PHMSA’s proposed alternate actions alone will not address the safety of existing low-pressure gas distribution systems and the safety deficiencies identified by NTSB’s investigation. Section 206 of the PIPES Act of 2020 requires PHMSA to promulgate regulations to ensure that operators adequately address overpressurization events and common modes of failure. PHMSA plans to address these provisions in a future NPRM titled Pipeline Safety: Safety of Gas Distribution Pipelines. According to PHMSA’s December 2021 PIPES 2020 Act Web Chart, PHMSA plans to publish the NPRM in July 2022.

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: 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.