{"operation":"document","citation":"PLD24MR005","title":"Enbridge Inc. Natural Gas–Fueled Building Explosion","source_type":"incident","agency":"National Transportation Safety Board","status":"current","official":true,"published_on":"2025-09-03","effective_on":"2024-05-28","summary":"Accident. in Youngstown, OH, USA. on 2024-05-28. Enbridge Gas Ohio. Rupture/release","machine_formats":{"json":"https://regulus.evalyn.ai/document/ntsb-case-pld24mr005.json","markdown":"https://regulus.evalyn.ai/document/ntsb-case-pld24mr005.md"},"app_url":"https://regulus.evalyn.ai/document/ntsb-case-pld24mr005","source_url":"https://www.ntsb.gov/investigations/Pages/PLD24MR005.aspx","body":"NTSB investigation PLD24MR005.\n\nEvent Type: Accident\n\nEvent Date: 2024-05-28\n\nEvent City: Youngstown\n\nEvent State Or Region: OH\n\nEvent Country: USA\n\nPipeline Operator: Enbridge Gas Ohio\n\nPipeline Type: Distribution\n\nAccident Type: Rupture/release\n\nCompletion Status: Completed\n\nReport Number: PIR2503\n\nReport Date: 2025-08-11\n\nProbable cause: The National Transportation Safety Board determines that the probable cause of the explosion and subsequent fatality was a cut by a scrap-removal crew into an active Enbridge Inc. service line, which was incorrectly documented as having been abandoned years earlier by the pipeline owner at the time, Dominion Energy Inc., and which allowed natural gas to leak into the Realty Building where it was ignited by an unknown source. Contributing to the severity of the accident were Chase Bank’s emergency procedures that did not require employees to immediately evacuate upon being alerted to a natural gas leak.\n\nTier1Name: System operating, changing flow/pressure\n\nTier2Name: Product leak/release\n\nTier1Name: Emergency response\n\nTier2Name: Evacuation\n\nTier1Name: Post-release\n\nTier2Name: Emergency response\n\nTier1Name: Post-release\n\nTier2Name: Emergency shutoff\n\nTier1Name: System not operating\n\nTier2Name: Explosion\n\nTier1Name: System not operating\n\nTier2Name: External/third-party damage\n\nTier1Name: System operating\n\nTier2Name: System disabled\n\nFinding Tier1Name: Organizational\n\nFinding Tier2Name: Support/oversight/monitoring\n\nFinding Tier3Name: Documentation/record keeping\n\nFinding Modifier Name: Pipeline operator\n\nFinding Report Text: Organizational - Support/oversight/monitoring - Documentation/record keeping - Pipeline operator\n\nFinding Tier1Name: Organizational\n\nFinding Tier2Name: Management\n\nFinding Tier3Name: Policy/procedure\n\nFinding Modifier Name: Other institution/organization\n\nFinding Report Text: Organizational - Management - Policy/procedure - Other institution/organization\n\nFinding Tier1Name: Pipeline\n\nFinding Tier2Name: Pipline systems/equipment\n\nFinding Tier3Name: (general)\n\nFinding Modifier Name: Damaged/degraded\n\nFinding Report Text: Pipeline - Pipline systems/equipment - (general) - Damaged/degraded\n\nOfficial NTSB investigation data. NTSB findings determine probable cause and make safety recommendations; they do not adjudicate civil liability or regulatory violations.\n\nWhat Happened\nOn May 28, 2024, about 2:44 p.m. local time, a natural gas–fueled explosion at the Realty Building in Youngstown, Ohio, caused 1 fatality and 9 injuries that required hospitalization. The natural gas originated from a 1-inch-diameter steel service line (accident service line) in the building’s basement. The explosion also caused significant structural damage to the building, which contained a Chase Bank and 22 apartment residences. Weather conditions at the time of the accident were 70°F with 14-mph winds and no precipitation.\n\nSee the photos on\nFlickr.\n\nWhat We Found\nWe determined that the probable cause of the explosion and subsequent fatality was a cut by a scrap-removal crew into an active Enbridge Inc. service line, which was incorrectly documented as having been abandoned years earlier by the pipeline owner at the time, Dominion Energy Inc., and which allowed natural gas to leak into the Realty Building where it was ignited by an unknown source. Contributing to the severity of the accident were Chase Bank’s emergency procedures that did not require employees to immediately evacuate upon being alerted to a natural gas leak.\n\nLessons Learned\nDocument Pipeline Abandonment and Deactivation Activities\nNatural gas pipeline operators must accurately document their pipeline abandonment and deactivation activities to prevent pipeline damage and accidental releases similar to this accident.\nIn 2017, the NTSB also investigated a fatal home explosion in Firestone, Colorado, that resulted from natural gas migrating from an improperly abandoned underground facility into the basement of a residence, further underscoring the importance of proper pipeline abandonment.\nAfter the accident in Youngstown, the Public Utilities Commission of Ohio oversaw Enbridge’s excavation of 10 service lines that were documented as abandoned around the same time as the accident service line.\nEnbridge found that two of these service lines were still pressurized with gas.\nEnbridge also reported after the accident that it was investigating 5,951 other pipelines that were documented as abandoned but whose records contained inconsistent or unconfirmed data.\nThe company found that 79 of these pipelines were active. Enbridge subsequently properly abandoned them according to the new procedure and updated their corresponding records.\n\nIn August 2024, Enbridge issued a pipeline safety alert advising crews about a revised practice for disconnecting and abandoning service lines. According to the revised practice, before completing a service line cut order, the pipeline must be exposed for visual confirmation that the service line has been effectively cut from the main and capped off. Training materials have been updated to reinforce the revised practice. Enbridge also is installing warning tags on their interior piping assets to alert customers of the presence of pressurized gas and how to contact the gas company.\nAfter the accident, Chase Bank revised its emergency guidelines and employee training to require immediate evacuation during incidents involving gas leaks.\n\nOhio Edison revised training courses for employees on its emergency processes to reiterate the importance of coordinating and communicating with external incident commanders during all incidents, including those in which no specific work order has been given, to facilitate timely response in emergency situations and reduce delays.\n\nPIR-25-03\n<<<PAGE 1>>>\n\nPipeline Investigation Report\nPIR-25-03\nIssued: August 11, 2025 Pipeline Investigation Report: PIR-25-03\nEnbridge Inc. Natural Gas–Fueled\nBuilding Explosion\nLocation Youngstown, Ohio\nDate May 28, 2024\nSystem type Natural gas distribution\nAccident type Rupture/release\nPipeline operator Enbridge Gas Ohio (Enbridge Inc.)\nHazardous materials Natural gas\nFatalities 1\nInjuries 9\nProperty damage $42 million\n1 Factual Information\n1.1 The Accident\nOn May 28, 2024, about 2:44 p.m. local time, a natural gas–fueled explosion at\nthe Realty Building in Youngstown, Ohio, caused 1 fatality and 9 injuries that required\nhospitalization.1 The natural gas originated from a 1-inch-diameter steel service line\n(accident service line) in the building’s basement.\n2 The explosion also caused significant\nstructural damage to the building, which contained a Chase Bank and 22 apartment\nresidences. Weather conditions at the time of the accident were 70°F with 14-mph winds\nand no precipitation.\n1.1.1 Natural Gas Distribution System\nDominion Energy Inc. subsidiary Dominion Energy Ohio operated the natural gas\ndistribution system in the area of the accident until March 2024, when the company was\npurchased by Enbridge Inc. and became the subsidiary Enbridge Gas Ohio.3 At the time\n1 All times in this report are local. Visit ntsb.gov to find additional information in the public docket for\nthis NTSB accident investigation (case number PLD24MR005), including detailed factual reports about the\ncircumstances of the accident.\n2 Service lines transport gas from the distribution system to a customer.\n3 This report uses the current company name, Enbridge, throughout.\n1\n\n<<<PAGE 2>>>\n\nPipeline Investigation Report\nPIR-25-03\nof the accident, Enbridge provided natural gas to the businesses and residences in the\n13-story Realty Building through a 3-inch-diameter steel main and a 2-inch-diameter\nplastic service line, referred to in this report as the active service line, which led to a bank\nof gas meters on the east side of the building.\n4 (See figure 1.) The accident service line\nwas pressurized with natural gas to about 38 pounds per square inch, gauge, below the\nmaximum allowable operating pressure of 60 pounds per square inch, gauge.\nFigure 1. Realty Building after the explosion, with approximate locations of underground assets\ndepicted in yellow. (Source: Mahoning County Sheriff’s Office.)\nThe National Transportation Safety Board (NTSB) reviewed Enbridge records,\nwhich contained a September 2015 service line cut order: a work order for the accident\n4 A main is a natural gas distribution pipeline that serves as a common source of supply for more than\none service line.\n2\n\n<<<PAGE 3>>>\n\nPipeline Investigation Report\nPIR-25-03\nservice line to be physically disconnected from the main.5 The records indicated that the\ncurb valve was closed and the accident service line disconnected at that time.\nTypically, such work orders were assigned to a crew that would perform and\ndocument the completed work in the electronic customer care system. Enbridge\nrepresentatives stated that this work order had been entered manually into the system in\nSeptember 2015 by a customer relations employee. They further stated that a manual\nentry like this was generally associated with paper documentation but that they did not\nfind such documentation.\n1.1.2 Accident Sequence\nJust before the accident, a four-person scrap-removal crew, engaged by\ncontractor GreenHeart Companies LLC (GreenHeart), was working in a basement\nunderneath the sidewalk section northeast of the Realty Building.\n6 GreenHeart, which\nwas contracted by the City of Youngstown to fill in the building basement vaults in\npreparation for a city road improvement project, had directed the scrap-removal crew to\nremove scrap materials such as wiring, pipes, and bricks from the basement.\nA January 18, 2024, design locate request, to the utilities protection service Ohio\n811 on behalf of the City of Youngstown, described the planned work as the\nabandonment of utilities vaults.\n7 An Enbridge contract locator had marked some of the\nnearby natural gas assets in yellow paint on January 23, 2024, and again on May 4, 2024,\nbut the accident service line was not marked either time.\n8 (See figure 2.)\n5 The meter associated with the service line had been disconnected and removed in 2008 during a\nremodeling project. A pipeline that is permanently removed from service is also called abandoned.\n6 GreenHeart was partial owner of the Realty Building, which has since been demolished.\n7 A design locate request is submitted to a utilities protection service to provide general information\nabout underground utilities locations, generally as part of project planning. Title 49 Code of Federal\nRegulations 192.614 requires pipeline operators to participate in qualified utilities protection services like\nOhio 811 that use data from utility owners to identify underground assets.\n8 Records indicate the markings were associated with locate requests submitted on January 18 and\nMay 1 related to the city project. A locate request for underground utilities to be located and marked\nbefore excavation is submitted to a utilities protection service separately from a design request.\n3\n\n<<<PAGE 4>>>\n\nPipeline Investigation Report\nPIR-25-03\nFigure 2. Pavement markings on May 4, 2024. (Source: Ohio 811.)\nIn interviews with the NTSB, GreenHeart employees stated that they were not\naware that there was natural gas in any of the pipelines in the Realty Building basement,\nnoting that the accident service line appeared old and rusty and did not have a gas\nmeter. (See figure 3.) The scrap-removal crewmember stated he used a saw to cut into\none of the pipes that his project supervisor had told him was inactive, or “dead,\n” but\npartway through the process, the crewmember heard a loud whistling sound and felt gas\nblowing into his face from the cut pipe.\n4\n\n<<<PAGE 5>>>\n\nPipeline Investigation Report\nPIR-25-03\nFigure 3. The accident service line. (Source: Public Utilities Commission of Ohio.)\nThe scrap-removal crew immediately exited the basement area and called 911 to\nreport the gas leak.9 About 2:39 p.m., as they exited, a crewmember pulled the fire alarm\non the first floor, which alerted building residents of the emergency. The alarm did not\nsound in the building’s commercial spaces, which included Chase Bank on the first\nfloor.10 Video footage showed crewmembers speaking with bank employees and\npounding on the windows of the bank to notify employees of the gas leak between 2:42\nand 2:43 p.m.\nThe video footage showed that one of the eight on-site Chase Bank employees\nevacuated upon being warned about the gas leak. The other seven remained inside the\n9 The Youngstown Fire Department also received gas odor reports from the public, and notification\nfrom the Realty Building fire alarm, just before the explosion.\n10 In accordance with building codes, the fire protection system in Chase Bank was a separate system\nfrom that of the residential building. At least one Chase Bank employee had heard the residential fire alarm\nand left the bank to investigate the situation before returning to the building.\n5\n\n<<<PAGE 6>>>\n\nPipeline Investigation Report\nPIR-25-03\nRealty Building for about 2 minutes, packing up offices and alerting coworkers. These\nemployees were still inside at the time of the explosion about 2:44 p.m.; one employee\nwas standing near the bank’s main entrance door and was killed when the floor he was\nstanding on collapsed into the basement space. All but one of the apartment occupants\nevacuated before the explosion. Two of the Chase Bank employees sustained serious\ninjuries, and five sustained minor injuries. One of the apartment occupants and one\nemployee of the hotel across the street also sustained minor injuries.\n1.2 Emergency Response\nEmergency response teams from the Youngstown Fire Department, Youngstown\nPolice Department, Emergency Medical Transport, Mahoning County Sheriff’s Office,\nand Boardman Fire Rescue District responded to the accident, establishing an incident\ncommand and transporting victims to local hospitals for treatment. About 2:53 p.m., the\nincident commander requested Enbridge shut off gas service to the immediate area.\nEnbridge crews responded and isolated (stopped) the gas flow to the affected area by\n3:33 p.m.\nThe incident commander requested personnel from the electric utility First\nEnergy–Ohio Edison (Ohio Edison) to shut off power to the Realty Building about\n3:06 p.m.11 About 4:19 p.m., the incident commander paused search and rescue\noperations because water was filling the Realty Building basement from a water main\nthat had broken in the explosion, and electricity in the building was still on. Ohio Edison\nrecords indicate that crews had been dispatched about 3:17 p.m. but left when they\nwere unable to gain access to the accident scene. Ohio Edison personnel returned to the\nscene and shut off power about 6:25 p.m., and search and rescue operations resumed.\n1.3 Postaccident Tests and Evaluations\nAfter the accident, on May 28, Enbridge conducted an initial pressure test of the\nmain and service line to the Realty Building. The pipeline failed to hold pressure, and\ncrews heard a hissing noise from the pipeline in the basement that the scrap-removal\ncrewmember had cut into just before the accident.\nNTSB evaluations indicated that the accident service line was still connected to\nthe main, and the curb valve to the accident service line was in the open position,\nallowing gas to flow from the main into the service line.\n12 As part of Enbridge’s response\nto the design locate request, they located the main and active service lines to the\n11 Between 3:15 and 5:15 p.m., emergency response personnel made several calls to Ohio Edison to\nshut off power.\n12 A curb valve is a manually operated valve located on the service line near its connection to the gas\nmain.\n6\n\n<<<PAGE 7>>>\n\nPipeline Investigation Report\nPIR-25-03\nbuilding and marked the ground above the lines in yellow paint. There were no yellow\npaint markings outside or inside the building indicating that the accident service line was\npressurized with gas.\n1.4 Procedures\n1.4.1 Enbridge\nEnbridge procedures at the time of the recorded accident service line\nabandonment (and at the time of the accident) required that when abandoning a\npipeline, all pipeline facilities must be disconnected from all sources and supplies of gas,\npurged of gas, and sealed at both ends.13 Procedures specifically for service lines\nrequired curb valves to be removed or closed and service lines to be disconnected as\nclose to the main as possible.\n1.4.2 Chase Bank\nThe Chase Bank employees had previously received training on emergency\nprocedures, which at the time of the accident required immediate evacuation in the\nevent of smoke, fire, or the activation of the business’s fire alarm system. The procedures\ndid not require immediate evacuation upon the report of a natural gas leak, stating\ninstead that employees may evaluate their level of safety and determine the timing of\ntheir evacuation from the building accordingly for conditions that did not include smoke,\nfire, or alarm activation.\n2 Analysis\n2.1 Accident Summary\nNatural gas was released into the basement of the Realty Building and caused an\nexplosion in Youngstown, Ohio, after a member of a scrap removal crew cut into a steel\npipeline. Although the cut pipeline had not been marked or otherwise identified as\ncontaining natural gas, it did contain gas, pressurized at about 38 psig, which released\ninto the building and fueled the explosion.\n2.2 Inaccurate Records\nThe NTSB reviewed work order records related to the accident service line and\nnoted these records were inaccurate. Enbridge’s work order records from 2015\n13 (a) Enbridge used many Dominion procedures after the 2024 acquisition. (b) Pipeline facilities refer\nto pipes, fittings, and other components of a pipeline system.\n7\n\n<<<PAGE 8>>>\n\nPipeline Investigation Report\nPIR-25-03\nindicated the curb valve had been closed, but NTSB investigators found the valve in the\nopen position after the accident. Further, although the 2015 records indicated the\naccident service line had been disconnected from the main, the gas flowing through the\npipeline after the scrap-removal crew member cut into it, as well as a postaccident\npressure test, indicated that the service line was still connected to the gas system and\ncontained natural gas. Enbridge’s procedures regarding service line abandonment\nrequired curb valves to be removed or closed and service lines to be disconnected as\nclose to the main as possible. The procedure did not include a requirement for the work\ncrew to visually confirm the service line was disconnected from the main before\nprocessing the service line cut order.\nThe City of Youngstown submitted a design locate request to Ohio’s 811 center in\nJanuary 2024, so Enbridge was aware of the project; further, twice before the accident\n(in January and again in May) a contractor for the natural gas distribution operator had\nlocated both the main and the active service line and had marked their path on the\nground above them with yellow paint. Ohio 811 uses mapping data from its members\n(gas companies and other utility owners) to notify them of upcoming work so that the\nutility owners can locate and mark underground assets. Natural gas system maps at the\ntime of the city’s locate request to Ohio 811 did not include information about the\naccident service line, so the Enbridge crew sent to mark the gas lines was unaware of\nand thus did not mark the accident service line. Although GreenHeart did not directly\nverify with Enbridge whether the accident service line was transporting gas before\ncutting into it, had they done so, the inaccurate records and lack of any visual indication\nthat the line was active may have hampered Enbridge using their standard procedures\nfrom discovering that the service line still contained gas under pressure and therefore\nfrom providing a valid assessment of the pipe’s status.\n2.3 Emergency Procedures\nChase Bank’s emergency procedures required immediate evacuation for certain\nsituations such as smoke, fire, or an activated fire alarm. The procedures did not require\nimmediate evacuation for a natural gas leak and assigned less urgency to such a\nsituation, allowing employees to personally evaluate whether to evacuate immediately.\nVideo footage showed that, although one Chase Bank employee evacuated the building\nafter being notified of the gas leak about 2:42 p.m., other Chase Bank employees\nremained inside the Realty Building for about 2 minutes. Consequently, seven\nemployees were still inside the building when it exploded about 2:44 p.m., one of whom\nwas killed. Chase Bank’s emergency procedures did not adequately inform employees\nof the extreme hazard associated with a natural gas leak and the need for immediate\nevacuation. Had the bank employees evacuated immediately upon being alerted of the\ngas leak, they may have escaped injury.\nThe incident commander requested Ohio Edison to dispatch personnel to the\nscene of the accident to shut off power about 3:06 p.m., but the personnel were unable\nto gain access to the area and left. Search and rescue operations were suspended from\n8\n\n<<<PAGE 9>>>\n\nPipeline Investigation Report\nPIR-25-03\nabout 4:19 p.m. until Ohio Edison crews returned and shut off the power about\n6:25 p.m. The delay of more than 2 hours might have been avoided with better\ncommunication among Ohio Edison crews and external incident commanders.\n3 Probable Cause\nThe National Transportation Safety Board determines that the probable cause of\nthe explosion and subsequent fatality was a cut by a scrap-removal crew into an active\nEnbridge Inc. service line, which was incorrectly documented as having been\nabandoned years earlier by the pipeline owner at the time, Dominion Energy Inc., and\nwhich allowed natural gas to leak into the Realty Building where it was ignited by an\nunknown source. Contributing to the severity of the accident were Chase Bank’s\nemergency procedures that did not require employees to immediately evacuate upon\nbeing alerted to a natural gas leak.\n4 Lessons Learned\nNatural gas pipeline operators must accurately document their pipeline\nabandonment and deactivation activities to prevent pipeline damage and accidental\nreleases similar to this accident. In 2017, the NTSB also investigated a fatal home\nexplosion in Firestone, Colorado, that resulted from natural gas migrating from an\nimproperly abandoned underground facility into the basement of a residence, further\nunderscoring the importance of proper pipeline abandonment.\n14\nAfter the accident in Youngstown, the Public Utilities Commission of Ohio\noversaw Enbridge’s excavation of 10 service lines that were documented as abandoned\naround the same time as the accident service line. Enbridge found that two of these\nservice lines were still pressurized with gas. Enbridge also reported after the accident\nthat it was investigating 5,951 other pipelines that were documented as abandoned but\nwhose records contained inconsistent or unconfirmed data. The company found that 79\nof these pipelines were active. Enbridge subsequently properly abandoned them\naccording to the new procedure and updated their corresponding records.\nIn August 2024, Enbridge issued a pipeline safety alert advising crews about a\nrevised practice for disconnecting and abandoning service lines. According to the\nrevised practice, before completing a service line cut order, the pipeline must be\nexposed for visual confirmation that the service line has been effectively cut from the\nmain and capped off. Training materials have been updated to reinforce the revised\npractice. Enbridge also is installing warning tags on their interior piping assets to alert\ncustomers of the presence of pressurized gas and how to contact the gas company.\n14 NTSB. 2019. Natural Gas Explosion at Family Residence, Firestone, Colorado, April 17, 2017.\nPAB-19/02. Washington, DC: NTSB.\n9\n\n<<<PAGE 10>>>\n\nPipeline Investigation Report\nPIR-25-03\nAfter the accident, Chase Bank revised its emergency guidelines and employee\ntraining to require immediate evacuation during incidents involving gas leaks.\nOhio Edison revised training courses for employees on its emergency processes\nto reiterate the importance of coordinating and communicating with external incident\ncommanders during all incidents, including those in which no specific work order has\nbeen given, to facilitate timely response in emergency situations and reduce delays.\n10\n\n<<<PAGE 11>>>\n\nPipeline Investigation Report\nPIR-25-03\nThe NTSB is an independent federal agency charged by Congress with\ninvestigating every civil aviation accident in the United States and significant events in the\nother modes of transportation—railroad, transit, highway, marine, pipeline, and\ncommercial space. We determine the probable causes of the accidents and events we\ninvestigate and issue safety recommendations aimed at preventing future occurrences. In\naddition, we conduct transportation safety research studies and offer information and\nother assistance to family members and survivors for each accident or event we\ninvestigate. We also serve as the appellate authority for enforcement actions involving\naviation and mariner certificates issued by the Federal Aviation Administration (FAA) and\nUS Coast Guard, and we adjudicate appeals of civil penalty actions taken by the FAA.\nThe NTSB does not assign fault or blame for an accident or incident; rather, as\nspecified by NTSB regulation, “accident/incident investigations are fact-finding\nproceedings with no formal issues and no adverse parties … and are not conducted for\nthe purpose of determining the rights or liabilities of any person” (Title 49 Code of\nFederal Regulations section 831.4). Assignment of fault or legal liability is not relevant to\nthe NTSB’s statutory mission to improve transportation safety by investigating accidents\nand incidents and issuing safety recommendations. In addition, statutory language\nprohibits the admission into evidence or use of any part of an NTSB report related to an\naccident in a civil action for damages resulting from a matter mentioned in the report\n(Title 49 United States Code section 1154(b)).\nFor more detailed background information on this report, visit the NTSB Case\nAnalysis and Reporting Online (CAROL) website and search for NTSB accident ID\nPLD24MR005. Recent publications are available in their entirety on the NTSB website.\nOther information about available publications also may be obtained from the website or\nby contacting—\nNational Transportation Safety Board\nRecords Management Division, CIO-40\n490 L’Enfant Plaza, SW\nWashington, DC 20594\n(800) 877-6799 or (202) 314-6551\n11","truncated":false,"body_characters":26602}