# NTSB Safety Recommendation P-18-005 **Citation:** P-18-005 **Type / status:** guidance / guidance **Agency:** National Transportation Safety Board **Effective:** 2018-11-15 **Published:** 2018-11-15 TO THE COMMONWEALTH OF MASSACHUSETTS: Eliminate the professional engineer licensure exemption for public utility work and require a professional engineer’s seal on public utility engineering drawings. ## Document text NTSB safety recommendation P-18-005. TO THE COMMONWEALTH OF MASSACHUSETTS: Eliminate the professional engineer licensure exemption for public utility work and require a professional engineer’s seal on public utility engineering drawings. Priority: CLASS II Overall Status: Closed - Acceptable Action Issued Date: 2018-11-15 Adopted Date: 2018-11-14 Overall Date Closed: 2019-10-24 Synopsis: On September 13, 2018, about 4:00 p.m. eastern daylight time, a series of explosions and fires occurred after high-pressure natural gas was released into a low-pressure gas distribution system in the northeast region of the Merrimack Valley, Massachusetts. The distribution system was owned and operated by Columbia Gas of Massachusetts (Columbia Gas), a subsidiary of NiSource, Inc. The system overpressure 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 was a result of structure fires ignited by gas-fueled appliances. Several structures were destroyed by natural gas explosions. One person was killed and at least 21 individuals, including 2 firefighters, were transported to the hospital. Seven other firefighters received minor injuries. 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. Ntsbnumber: PLD18MR003 Report Number: PSR-18-02 Addressee Name: Commonwealth of Massachusetts Addressee Status: Closed - Acceptable Action Addressee Date Closed: 2019-10-24 Addressee Acronym: MA Addressee Organization Type: S-State 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. Updates to Operations and Maintenance (O&M) Procedural Manuals NPRM Commentary In the NPRM, PHMSA proposes updates to O&M procedural manuals to (1) account for the response and correction of overpressurization indications, (2) ensure a management of change process when an operator makes certain changes that could impact the integrity or safety of a gas distribution system, and (3) require that operators ensure qualified personnel review and certify certain construction plans. In the discussion for the third proposed update, the NPRM cites Safety Recommendation P 19 16, which recommends that states require professional engineer (PE) approval for natural gas infrastructure projects. The NPRM expresses concern that the lack of PEs in states could cause delays in critical construction projects; therefore, PHMSA proposes to allow individuals other than licensed PEs to be considered qualified to review construction plans. NTSB Comment We focus on the third proposed change, which would add a requirement that operators ensure qualified personnel review certain construction projects. Our Merrimack Valley investigation indicated that PE approval should be an essential component of construction plans that affect public safety. In the investigation, we noted that had the comprehensive constructability review of the operator’s pipeline construction project plan required a PE’s seal, it would have likely identified a critical omission in the plan and prevented the error that led to the accident. Our investigation recognized that a PE license is a valued credential, especially for engineering projects affecting public safety. The investigation report provides several reasons that we value the PE credential, noting that (1) it conveys that the holder maintains and demonstrates technical competency; (2) PEs are bound to a code of ethics, which creates a duty to hold public safety, health, and welfare paramount and to perform services only in the areas of their competence; and (3) PEs are personally accountable for the work they approve and stamp, and they must exercise responsible charge over all aspects of the work. As a result of our investigation, we issued three safety recommendations on this topic. We issued Safety Recommendation P 18 5 to the Commonwealth of Massachusetts to eliminate the PE licensure exemption for public utility work and require a PE’s seal on public utility engineering drawings. After Massachusetts enacted a law requiring that licensed PEs review and approve engineering plans developed by or on behalf of natural gas companies, we classified the recommendation as Closed—Acceptable Action. We also issued Safety Recommendation P 18 6 to the operator to revise its engineering plan and constructability review process to ensure that all applicable departments review construction plans and that a PE seals these plans before starting work. After the operator developed criteria for when PE approval is necessary and when it is not, we classified the recommendation as Closed—?Acceptable Action. Finally, we issued Safety Recommendation P 19 16 to 31 states that allow exemptions to PE approval and stamping for natural gas infrastructure projects, calling for them to remove the exemption so that all future natural gas infrastructure projects require licensed PE approval and stamping. One of the three states that has satisfied this recommendation, Maryland, did so by removing the PE exemption and developing criteria for “covered” projects, which require PE approval, and for “noncovered” projects, which can be reviewed by a relevant, qualified person. The NTSB believes that the NPRM’s third proposed change to O&M procedural manuals, which would require that qualified personnel, rather than PEs, review and certify certain construction plans, does not address the intent of our safety recommendations on this topic. We acknowledge that not all projects may require PE approval, such as those that do not pose a risk to public safety. Therefore, in our view, PHMSA and state regulators should develop specific criteria for determining the types of projects that require PE approval and those that do not. We encourage PHMSA to include this approach in the final rule. 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: MA Addressee Organization Type: S-State Government Communication Date: 2018-11-15 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. On November 14, 2018, the National Transportation Safety Board (NTSB) adopted its safety recommendation report, Natural Gas Distribution System Project Development and Review PSR 18/02. The details of this safety recommendation report may be found at http://www.ntsb.gov. Among the safety recommendations is one issued to the Commonwealth of Massachusetts, which can be found on page 7 of the report. The NTSB is vitally interested in is recommendation because it is designed to prevent accidents and save lives. We would appreciate a response within 90 days, detailing the actions you have taken or intend to take to implement these recommendations. When replying, please refer to the safety recommendation by number. We encourage you to submit your response to correspondence@ntsb.gov. If it exceeds 10 megabytes, including attachments, 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: MA Addressee Organization Type: S-State Government Communication Date: 2019-10-24 Communication Type: Report Reclassification Communication Contents: From NTSB Report PAR-19-02: Overpressurization of Natural Gas Distribution System, Explosions, and Fires in Merrimack Valley, Massachusetts, September 13, 2018: 2.1 NTSB Safety Recommendation to Commonwealth of Massachusetts At the time of the accident, a Massachusetts P.E. stamp was not required on any utility system construction, operations, or maintenance projects as local natural gas distribution companies in the state had a utility exemption from requiring a P.E.’s stamp. On November 14, 2018, the NTSB issued a safety recommendation report, Natural Gas Distribution System Project Development and Review, in response to this accident and the events that followed (NTSB 2018). According to the report: The Commonwealth of Massachusetts’ exemption for the requirement of registered Professional Engineer (P.E.) to perform industrial and public utility work limits the opportunities for competently trained and experienced engineers to uncover system design and work process deficiencies. By eliminating the exemption, especially for systems involving inherently dangerous materials such as natural gas distribution systems, companies, workers, and the public are provided greater safety assurance that competent and qualified engineers, who are ethically bound to work only on projects within the scope of their expertise, will review, assess, and execute the requisite work activities according to best engineering practices and with expected safeguards. As a result of this investigation, the NTSB issued Safety Recommendation P-18-5 to the Commonwealth of Massachusetts Eliminate the professional engineer licensure exemption for public utility work and require a professional engineer’s seal on public utility engineering drawings. (P-18-5) Less than 2 months after the safety recommendation was issued, on December 28, 2018, Bill H.5005, requiring that licensed P.E.s review and approve engineering plans developed by or on behalf of natural gas companies, to ensure the safe construction, operation, and maintenance of natural gas infrastructure, was passed by the Massachusetts House of Representatives. The act applies to engineering work or services on natural gas distribution systems that could pose a material risk to public safety, as determined by the DPU, performed by or on behalf of a natural gas company. Moreover, the act requires any engineering plans or specifications for engineering work or services that could pose a material risk to public safety, developed by or on behalf of a natural gas company, to bear the stamp of approval of a licensed P.E.39 After the Massachusetts Senate passed the act, it was signed by the governor on December 31, 2018, as Chapter 339 of the Acts of 2018. This new law included an emergency preamble and took effect immediately. Because it required natural gas work that might pose a material risk to the public be reviewed and approved by a certified P.E., Safety Recommendation P-18-5 is classified CLOSED--ACCEPTABLE ACTION. ## Provenance - Official: Yes - Source: - Source ID: `ntsb-pipeline` - SHA-256: `2f26b8ee746d97b3af00b6f93f8d29de3973733bc5979a9f6a8b3faef25d56c3` - Retrieved: 2026-08-20T04:57:24.741Z - Exported: 2026-08-22T22:43:07.591Z - Document slug: `ntsb-recommendation-p-18-005` ### Source metadata ```json { "recordKind": "ntsb_safety_recommendation", "safetyRecommendationNumber": "P-18-005", "recommendationMode": "Pipeline", "topicMode": "Pipeline", "ntsbNumber": "PLD18MR003", "priority": "CLASS II", "overallStatus": "Closed - Acceptable Action", "overallStatusAcronym": "CAA", "overallDateClosed": "2019-10-24", "lastModifiedDate": "2023-10-30", "reportNumber": "PSR-18-02", "reportUrl": "https://www.ntsb.gov/investigations/Pages/PLD18MR003.aspx", "transmittalLetterUrl": "http://www.ntsb.gov/safety/safety-recs/recletters/P-18-005-009.pdf", "addressees": [ { "addresseeName": "Commonwealth of Massachusetts", "addresseeStatusAcronym": "CAA", "addresseeStatus": "Closed - Acceptable Action", "addresseeDateClosed": "2019-10-24", "addresseeDetails": [ { "addresseeAcronym": "MA", "addresseeOrganizationType": "S-State Government", "isFromNtsb": true, "communicationDate": "2023-10-27", "communicationType": "NPRM Response", "communicationContents": "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. \r\n\r\nThe 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.\r\n\r\nRelated NTSB Investigations \r\nIn 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. \r\nIn 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.\r\n\r\nUpdates to Operations and Maintenance (O&M) Procedural Manuals\r\n\r\nNPRM Commentary\r\n\r\n\tIn the NPRM, PHMSA proposes updates to O&M procedural manuals to (1) account for the response and correction of overpressurization indications, (2) ensure a management of change process when an operator makes certain changes that could impact the integrity or safety of a gas distribution system, and (3) require that operators ensure qualified personnel review and certify certain construction plans. \r\n\r\nIn the discussion for the third proposed update, the NPRM cites Safety Recommendation P 19 16, which recommends that states require professional engineer (PE) approval for natural gas infrastructure projects. The NPRM expresses concern that the lack of PEs in states could cause delays in critical construction projects; therefore, PHMSA proposes to allow individuals other than licensed PEs to be considered qualified to review construction plans.\r\n\r\nNTSB Comment\r\n\r\nWe focus on the third proposed change, which would add a requirement that operators ensure qualified personnel review certain construction projects. \r\n\r\nOur Merrimack Valley investigation indicated that PE approval should be an essential component of construction plans that affect public safety. In the investigation, we noted that had the comprehensive constructability review of the operator’s pipeline construction project plan required a PE’s seal, it would have likely identified a critical omission in the plan and prevented the error that led to the accident. \r\n\r\nOur investigation recognized that a PE license is a valued credential, especially for engineering projects affecting public safety. The investigation report provides several reasons that we value the PE credential, noting that (1) it conveys that the holder maintains and demonstrates technical competency; (2) PEs are bound to a code of ethics, which creates a duty to hold public safety, health, and welfare paramount and to perform services only in the areas of their competence; and (3) PEs are personally accountable for the work they approve and stamp, and they must exercise responsible charge over all aspects of the work. As a result of our investigation, we issued three safety recommendations on this topic.\r\n\r\nWe issued Safety Recommendation P 18 5 to the Commonwealth of Massachusetts to eliminate the PE licensure exemption for public utility work and require a PE’s seal on public utility engineering drawings. After Massachusetts enacted a law requiring that licensed PEs review and approve engineering plans developed by or on behalf of natural gas companies, we classified the recommendation as Closed—Acceptable Action. \r\n\r\nWe also issued Safety Recommendation P 18 6 to the operator to revise its engineering plan and constructability review process to ensure that all applicable departments review construction plans and that a PE seals these plans before starting work. After the operator developed criteria for when PE approval is necessary and when it is not, we classified the recommendation as Closed—?Acceptable Action. \r\n\r\nFinally, we issued Safety Recommendation P 19 16 to 31 states that allow exemptions to PE approval and stamping for natural gas infrastructure projects, calling for them to remove the exemption so that all future natural gas infrastructure projects require licensed PE approval and stamping. One of the three states that has satisfied this recommendation, Maryland, did so by removing the PE exemption and developing criteria for “covered” projects, which require PE approval, and for “noncovered” projects, which can be reviewed by a relevant, qualified person. \r\n\r\nThe NTSB believes that the NPRM’s third proposed change to O&M procedural manuals, which would require that qualified personnel, rather than PEs, review and certify certain construction plans, does not address the intent of our safety recommendations on this topic. We acknowledge that not all projects may require PE approval, such as those that do not pose a risk to public safety. Therefore, in our view, PHMSA and state regulators should develop specific criteria for determining the types of projects that require PE approval and those that do not. We encourage PHMSA to include this approach in the final rule. \r\n\r\nSummary\r\n\r\n\tThe 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.\r\n\t\r\nThank you for the opportunity to comment on this notice." }, { "addresseeAcronym": "MA", "addresseeOrganizationType": "S-State Government", "isFromNtsb": true, "communicationDate": "2018-11-15", "communicationType": "Transmittal Letter", "communicationContents": "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. \r\n\r\nOn November 14, 2018, the National Transportation Safety Board (NTSB) adopted its safety recommendation report, Natural Gas Distribution System Project Development and Review PSR 18/02. The details of this safety recommendation report may be found at http://www.ntsb.gov.\r\n\r\nAmong the safety recommendations is one issued to the Commonwealth of Massachusetts, which can be found on page 7 of the report.\r\n\r\nThe NTSB is vitally interested in is recommendation because it is designed to prevent accidents and save lives. We would appreciate a response within 90 days, detailing the actions you have taken or intend to take to implement these recommendations. When replying, please refer to the safety recommendation by number. We encourage you to submit your response to correspondence@ntsb.gov. If it exceeds 10 megabytes, including attachments, 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." }, { "addresseeAcronym": "MA", "addresseeOrganizationType": "S-State Government", "isFromNtsb": true, "communicationDate": "2019-10-24", "communicationType": "Report Reclassification", "communicationContents": "From NTSB Report PAR-19-02: Overpressurization of Natural Gas Distribution System, Explosions, and Fires in Merrimack Valley, Massachusetts, September 13, 2018: 2.1 NTSB Safety Recommendation to Commonwealth of Massachusetts At the time of the accident, a Massachusetts P.E. stamp was not required on any utility system construction, operations, or maintenance projects as local natural gas distribution companies in the state had a utility exemption from requiring a P.E.’s stamp. On November 14, 2018, the NTSB issued a safety recommendation report, Natural Gas Distribution System Project Development and Review, in response to this accident and the events that followed (NTSB 2018). According to the report: \r\nThe Commonwealth of Massachusetts’ exemption for the requirement of registered Professional Engineer (P.E.) to perform industrial and public utility work limits the opportunities for competently trained and experienced engineers to uncover system design and work process deficiencies. By eliminating the exemption, especially for systems involving inherently dangerous materials such as natural gas distribution systems, companies, workers, and the public are provided greater safety assurance that competent and qualified engineers, who are ethically bound to work only on projects within the scope of their expertise, will review, assess, and execute the requisite work activities according to best engineering practices and with expected safeguards. \r\nAs a result of this investigation, the NTSB issued Safety Recommendation P-18-5 to the Commonwealth of Massachusetts \r\nEliminate the professional engineer licensure exemption for public utility work and require a professional engineer’s seal on public utility engineering drawings. (P-18-5) \r\nLess than 2 months after the safety recommendation was issued, on December 28, 2018, Bill H.5005, requiring that licensed P.E.s review and approve engineering plans developed by or on behalf of natural gas companies, to ensure the safe construction, operation, and maintenance of natural gas infrastructure, was passed by the Massachusetts House of Representatives. The act applies to engineering work or services on natural gas distribution systems that could pose a material risk to public safety, as determined by the DPU, performed by or on behalf of a natural gas company. Moreover, the act requires any engineering plans or specifications for engineering work or services that could pose a material risk to public safety, developed by or on behalf of a natural gas company, to bear the stamp of approval of a licensed P.E.39 After the Massachusetts Senate passed the act, it was signed by the governor on December 31, 2018, as Chapter 339 of the Acts of 2018. This new law included an emergency preamble and took effect immediately. Because it required natural gas work that might pose a material risk to the public be reviewed and approved by a certified P.E., Safety Recommendation P-18-5 is classified CLOSED--ACCEPTABLE ACTION." } ] } ], "jurisdiction": "US" } ```