# Enbridge Inc. Natural Gas–Fueled Building Explosion

**Citation:** PLD24MR005  
**Type / status:** incident / current  
**Agency:** National Transportation Safety Board  
**Effective:** 2024-05-28  
**Published:** 2025-09-03

Accident. in Youngstown, OH, USA. on 2024-05-28. Enbridge Gas Ohio. Rupture/release

## Document text

NTSB investigation PLD24MR005.

Event Type: Accident

Event Date: 2024-05-28

Event City: Youngstown

Event State Or Region: OH

Event Country: USA

Pipeline Operator: Enbridge Gas Ohio

Pipeline Type: Distribution

Accident Type: Rupture/release

Completion Status: Completed

Report Number: PIR2503

Report Date: 2025-08-11

Probable 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.

Tier1Name: System operating, changing flow/pressure

Tier2Name: Product leak/release

Tier1Name: Emergency response

Tier2Name: Evacuation

Tier1Name: Post-release

Tier2Name: Emergency response

Tier1Name: Post-release

Tier2Name: Emergency shutoff

Tier1Name: System not operating

Tier2Name: Explosion

Tier1Name: System not operating

Tier2Name: External/third-party damage

Tier1Name: System operating

Tier2Name: System disabled

Finding Tier1Name: Organizational

Finding Tier2Name: Support/oversight/monitoring

Finding Tier3Name: Documentation/record keeping

Finding Modifier Name: Pipeline operator

Finding Report Text: Organizational - Support/oversight/monitoring - Documentation/record keeping - Pipeline operator

Finding Tier1Name: Organizational

Finding Tier2Name: Management

Finding Tier3Name: Policy/procedure

Finding Modifier Name: Other institution/organization

Finding Report Text: Organizational - Management - Policy/procedure - Other institution/organization

Finding Tier1Name: Pipeline

Finding Tier2Name: Pipline systems/equipment

Finding Tier3Name: (general)

Finding Modifier Name: Damaged/degraded

Finding Report Text: Pipeline - Pipline systems/equipment - (general) - Damaged/degraded

Official NTSB investigation data. NTSB findings determine probable cause and make safety recommendations; they do not adjudicate civil liability or regulatory violations.

What Happened
On 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.

See the photos on
Flickr.

What We Found
We 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.

Lessons Learned
Document Pipeline Abandonment and Deactivation Activities
Natural gas pipeline operators must accurately document their pipeline abandonment and deactivation activities to prevent pipeline damage and accidental releases similar to this accident.
In 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.
After 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.
Enbridge found that two of these service lines were still pressurized with gas.
Enbridge 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.
The company found that 79 of these pipelines were active. Enbridge subsequently properly abandoned them according to the new procedure and updated their corresponding records.

In 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.
After the accident, Chase Bank revised its emergency guidelines and employee training to require immediate evacuation during incidents involving gas leaks.

Ohio 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.

PIR-25-03
<<<PAGE 1>>>

Pipeline Investigation Report
PIR-25-03
Issued: August 11, 2025 Pipeline Investigation Report: PIR-25-03
Enbridge Inc. Natural Gas–Fueled
Building Explosion
Location Youngstown, Ohio
Date May 28, 2024
System type Natural gas distribution
Accident type Rupture/release
Pipeline operator Enbridge Gas Ohio (Enbridge Inc.)
Hazardous materials Natural gas
Fatalities 1
Injuries 9
Property damage $42 million
1 Factual Information
1.1 The Accident
On 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.1 The natural gas originated from a 1-inch-diameter steel service line
(accident service line) in the building’s basement.
2 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.
1.1.1 Natural Gas Distribution System
Dominion Energy Inc. subsidiary Dominion Energy Ohio operated the natural gas
distribution system in the area of the accident until March 2024, when the company was
purchased by Enbridge Inc. and became the subsidiary Enbridge Gas Ohio.3 At the time
1 All times in this report are local. Visit ntsb.gov to find additional information in the public docket for
this NTSB accident investigation (case number PLD24MR005), including detailed factual reports about the
circumstances of the accident.
2 Service lines transport gas from the distribution system to a customer.
3 This report uses the current company name, Enbridge, throughout.
1

<<<PAGE 2>>>

Pipeline Investigation Report
PIR-25-03
of the accident, Enbridge provided natural gas to the businesses and residences in the
13-story Realty Building through a 3-inch-diameter steel main and a 2-inch-diameter
plastic service line, referred to in this report as the active service line, which led to a bank
of gas meters on the east side of the building.
4 (See figure 1.) The accident service line
was pressurized with natural gas to about 38 pounds per square inch, gauge, below the
maximum allowable operating pressure of 60 pounds per square inch, gauge.
Figure 1. Realty Building after the explosion, with approximate locations of underground assets
depicted in yellow. (Source: Mahoning County Sheriff’s Office.)
The National Transportation Safety Board (NTSB) reviewed Enbridge records,
which contained a September 2015 service line cut order: a work order for the accident
4 A main is a natural gas distribution pipeline that serves as a common source of supply for more than
one service line.
2

<<<PAGE 3>>>

Pipeline Investigation Report
PIR-25-03
service line to be physically disconnected from the main.5 The records indicated that the
curb valve was closed and the accident service line disconnected at that time.
Typically, such work orders were assigned to a crew that would perform and
document the completed work in the electronic customer care system. Enbridge
representatives stated that this work order had been entered manually into the system in
September 2015 by a customer relations employee. They further stated that a manual
entry like this was generally associated with paper documentation but that they did not
find such documentation.
1.1.2 Accident Sequence
Just before the accident, a four-person scrap-removal crew, engaged by
contractor GreenHeart Companies LLC (GreenHeart), was working in a basement
underneath the sidewalk section northeast of the Realty Building.
6 GreenHeart, which
was contracted by the City of Youngstown to fill in the building basement vaults in
preparation for a city road improvement project, had directed the scrap-removal crew to
remove scrap materials such as wiring, pipes, and bricks from the basement.
A January 18, 2024, design locate request, to the utilities protection service Ohio
811 on behalf of the City of Youngstown, described the planned work as the
abandonment of utilities vaults.
7 An Enbridge contract locator had marked some of the
nearby natural gas assets in yellow paint on January 23, 2024, and again on May 4, 2024,
but the accident service line was not marked either time.
8 (See figure 2.)
5 The meter associated with the service line had been disconnected and removed in 2008 during a
remodeling project. A pipeline that is permanently removed from service is also called abandoned.
6 GreenHeart was partial owner of the Realty Building, which has since been demolished.
7 A design locate request is submitted to a utilities protection service to provide general information
about underground utilities locations, generally as part of project planning. Title 49 Code of Federal
Regulations 192.614 requires pipeline operators to participate in qualified utilities protection services like
Ohio 811 that use data from utility owners to identify underground assets.
8 Records indicate the markings were associated with locate requests submitted on January 18 and
May 1 related to the city project. A locate request for underground utilities to be located and marked
before excavation is submitted to a utilities protection service separately from a design request.
3

<<<PAGE 4>>>

Pipeline Investigation Report
PIR-25-03
Figure 2. Pavement markings on May 4, 2024. (Source: Ohio 811.)
In interviews with the NTSB, GreenHeart employees stated that they were not
aware that there was natural gas in any of the pipelines in the Realty Building basement,
noting that the accident service line appeared old and rusty and did not have a gas
meter. (See figure 3.) The scrap-removal crewmember stated he used a saw to cut into
one of the pipes that his project supervisor had told him was inactive, or “dead,
” but
partway through the process, the crewmember heard a loud whistling sound and felt gas
blowing into his face from the cut pipe.
4

<<<PAGE 5>>>

Pipeline Investigation Report
PIR-25-03
Figure 3. The accident service line. (Source: Public Utilities Commission of Ohio.)
The scrap-removal crew immediately exited the basement area and called 911 to
report the gas leak.9 About 2:39 p.m., as they exited, a crewmember pulled the fire alarm
on the first floor, which alerted building residents of the emergency. The alarm did not
sound in the building’s commercial spaces, which included Chase Bank on the first
floor.10 Video footage showed crewmembers speaking with bank employees and
pounding on the windows of the bank to notify employees of the gas leak between 2:42
and 2:43 p.m.
The video footage showed that one of the eight on-site Chase Bank employees
evacuated upon being warned about the gas leak. The other seven remained inside the
9 The Youngstown Fire Department also received gas odor reports from the public, and notification
from the Realty Building fire alarm, just before the explosion.
10 In accordance with building codes, the fire protection system in Chase Bank was a separate system
from that of the residential building. At least one Chase Bank employee had heard the residential fire alarm
and left the bank to investigate the situation before returning to the building.
5

<<<PAGE 6>>>

Pipeline Investigation Report
PIR-25-03
Realty Building for about 2 minutes, packing up offices and alerting coworkers. These
employees were still inside at the time of the explosion about 2:44 p.m.; one employee
was standing near the bank’s main entrance door and was killed when the floor he was
standing on collapsed into the basement space. All but one of the apartment occupants
evacuated before the explosion. Two of the Chase Bank employees sustained serious
injuries, and five sustained minor injuries. One of the apartment occupants and one
employee of the hotel across the street also sustained minor injuries.
1.2 Emergency Response
Emergency response teams from the Youngstown Fire Department, Youngstown
Police Department, Emergency Medical Transport, Mahoning County Sheriff’s Office,
and Boardman Fire Rescue District responded to the accident, establishing an incident
command and transporting victims to local hospitals for treatment. About 2:53 p.m., the
incident commander requested Enbridge shut off gas service to the immediate area.
Enbridge crews responded and isolated (stopped) the gas flow to the affected area by
3:33 p.m.
The incident commander requested personnel from the electric utility First
Energy–Ohio Edison (Ohio Edison) to shut off power to the Realty Building about
3:06 p.m.11 About 4:19 p.m., the incident commander paused search and rescue
operations because water was filling the Realty Building basement from a water main
that had broken in the explosion, and electricity in the building was still on. Ohio Edison
records indicate that crews had been dispatched about 3:17 p.m. but left when they
were unable to gain access to the accident scene. Ohio Edison personnel returned to the
scene and shut off power about 6:25 p.m., and search and rescue operations resumed.
1.3 Postaccident Tests and Evaluations
After the accident, on May 28, Enbridge conducted an initial pressure test of the
main and service line to the Realty Building. The pipeline failed to hold pressure, and
crews heard a hissing noise from the pipeline in the basement that the scrap-removal
crewmember had cut into just before the accident.
NTSB evaluations indicated that the accident service line was still connected to
the main, and the curb valve to the accident service line was in the open position,
allowing gas to flow from the main into the service line.
12 As part of Enbridge’s response
to the design locate request, they located the main and active service lines to the
11 Between 3:15 and 5:15 p.m., emergency response personnel made several calls to Ohio Edison to
shut off power.
12 A curb valve is a manually operated valve located on the service line near its connection to the gas
main.
6

<<<PAGE 7>>>

Pipeline Investigation Report
PIR-25-03
building and marked the ground above the lines in yellow paint. There were no yellow
paint markings outside or inside the building indicating that the accident service line was
pressurized with gas.
1.4 Procedures
1.4.1 Enbridge
Enbridge procedures at the time of the recorded accident service line
abandonment (and at the time of the accident) required that when abandoning a
pipeline, all pipeline facilities must be disconnected from all sources and supplies of gas,
purged of gas, and sealed at both ends.13 Procedures specifically for service lines
required curb valves to be removed or closed and service lines to be disconnected as
close to the main as possible.
1.4.2 Chase Bank
The Chase Bank employees had previously received training on emergency
procedures, which at the time of the accident required immediate evacuation in the
event of smoke, fire, or the activation of the business’s fire alarm system. The procedures
did not require immediate evacuation upon the report of a natural gas leak, stating
instead that employees may evaluate their level of safety and determine the timing of
their evacuation from the building accordingly for conditions that did not include smoke,
fire, or alarm activation.
2 Analysis
2.1 Accident Summary
Natural gas was released into the basement of the Realty Building and caused an
explosion in Youngstown, Ohio, after a member of a scrap removal crew cut into a steel
pipeline. Although the cut pipeline had not been marked or otherwise identified as
containing natural gas, it did contain gas, pressurized at about 38 psig, which released
into the building and fueled the explosion.
2.2 Inaccurate Records
The NTSB reviewed work order records related to the accident service line and
noted these records were inaccurate. Enbridge’s work order records from 2015
13 (a) Enbridge used many Dominion procedures after the 2024 acquisition. (b) Pipeline facilities refer
to pipes, fittings, and other components of a pipeline system.
7

<<<PAGE 8>>>

Pipeline Investigation Report
PIR-25-03
indicated the curb valve had been closed, but NTSB investigators found the valve in the
open position after the accident. Further, although the 2015 records indicated the
accident service line had been disconnected from the main, the gas flowing through the
pipeline after the scrap-removal crew member cut into it, as well as a postaccident
pressure test, indicated that the service line was still connected to the gas system and
contained natural gas. Enbridge’s procedures regarding service line abandonment
required curb valves to be removed or closed and service lines to be disconnected as
close to the main as possible. The procedure did not include a requirement for the work
crew to visually confirm the service line was disconnected from the main before
processing the service line cut order.
The City of Youngstown submitted a design locate request to Ohio’s 811 center in
January 2024, so Enbridge was aware of the project; further, twice before the accident
(in January and again in May) a contractor for the natural gas distribution operator had
located both the main and the active service line and had marked their path on the
ground above them with yellow paint. Ohio 811 uses mapping data from its members
(gas companies and other utility owners) to notify them of upcoming work so that the
utility owners can locate and mark underground assets. Natural gas system maps at the
time of the city’s locate request to Ohio 811 did not include information about the
accident service line, so the Enbridge crew sent to mark the gas lines was unaware of
and thus did not mark the accident service line. Although GreenHeart did not directly
verify with Enbridge whether the accident service line was transporting gas before
cutting into it, had they done so, the inaccurate records and lack of any visual indication
that the line was active may have hampered Enbridge using their standard procedures
from discovering that the service line still contained gas under pressure and therefore
from providing a valid assessment of the pipe’s status.
2.3 Emergency Procedures
Chase Bank’s emergency procedures required immediate evacuation for certain
situations such as smoke, fire, or an activated fire alarm. The procedures did not require
immediate evacuation for a natural gas leak and assigned less urgency to such a
situation, allowing employees to personally evaluate whether to evacuate immediately.
Video footage showed that, although one Chase Bank employee evacuated the building
after being notified of the gas leak about 2:42 p.m., other Chase Bank employees
remained inside the Realty Building for about 2 minutes. Consequently, seven
employees were still inside the building when it exploded about 2:44 p.m., one of whom
was killed. Chase Bank’s emergency procedures did not adequately inform employees
of the extreme hazard associated with a natural gas leak and the need for immediate
evacuation. Had the bank employees evacuated immediately upon being alerted of the
gas leak, they may have escaped injury.
The incident commander requested Ohio Edison to dispatch personnel to the
scene of the accident to shut off power about 3:06 p.m., but the personnel were unable
to gain access to the area and left. Search and rescue operations were suspended from
8

<<<PAGE 9>>>

Pipeline Investigation Report
PIR-25-03
about 4:19 p.m. until Ohio Edison crews returned and shut off the power about
6:25 p.m. The delay of more than 2 hours might have been avoided with better
communication among Ohio Edison crews and external incident commanders.
3 Probable 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.
4 Lessons Learned
Natural gas pipeline operators must accurately document their pipeline
abandonment and deactivation activities to prevent pipeline damage and accidental
releases similar to this accident. In 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.
14
After 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. Enbridge found that two of these
service lines were still pressurized with gas. Enbridge 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. The company found that 79
of these pipelines were active. Enbridge subsequently properly abandoned them
according to the new procedure and updated their corresponding records.
In 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.
14 NTSB. 2019. Natural Gas Explosion at Family Residence, Firestone, Colorado, April 17, 2017.
PAB-19/02. Washington, DC: NTSB.
9

<<<PAGE 10>>>

Pipeline Investigation Report
PIR-25-03
After the accident, Chase Bank revised its emergency guidelines and employee
training to require immediate evacuation during incidents involving gas leaks.
Ohio 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.
10

<<<PAGE 11>>>

Pipeline Investigation Report
PIR-25-03
The NTSB is an independent federal agency charged by Congress with
investigating every civil aviation accident in the United States and significant events in the
other modes of transportation—railroad, transit, highway, marine, pipeline, and
commercial space. We determine the probable causes of the accidents and events we
investigate and issue safety recommendations aimed at preventing future occurrences. In
addition, we conduct transportation safety research studies and offer information and
other assistance to family members and survivors for each accident or event we
investigate. We also serve as the appellate authority for enforcement actions involving
aviation and mariner certificates issued by the Federal Aviation Administration (FAA) and
US Coast Guard, and we adjudicate appeals of civil penalty actions taken by the FAA.
The NTSB does not assign fault or blame for an accident or incident; rather, as
specified by NTSB regulation, “accident/incident investigations are fact-finding
proceedings with no formal issues and no adverse parties … and are not conducted for
the purpose of determining the rights or liabilities of any person” (Title 49 Code of
Federal Regulations section 831.4). Assignment of fault or legal liability is not relevant to
the NTSB’s statutory mission to improve transportation safety by investigating accidents
and incidents and issuing safety recommendations. In addition, statutory language
prohibits the admission into evidence or use of any part of an NTSB report related to an
accident in a civil action for damages resulting from a matter mentioned in the report
(Title 49 United States Code section 1154(b)).
For more detailed background information on this report, visit the NTSB Case
Analysis and Reporting Online (CAROL) website and search for NTSB accident ID
PLD24MR005. Recent publications are available in their entirety on the NTSB website.
Other information about available publications also may be obtained from the website or
by contacting—
National Transportation Safety Board
Records Management Division, CIO-40
490 L’Enfant Plaza, SW
Washington, DC 20594
(800) 877-6799 or (202) 314-6551
11

## Provenance

- Official: Yes
- Source: <https://www.ntsb.gov/investigations/Pages/PLD24MR005.aspx>
- Source ID: `ntsb-pipeline`
- SHA-256: `db126bb66565425b2734203663a6f47a12178a123246ed6bc2909f4841e336a0`
- Retrieved: 2026-08-20T04:57:25.499Z
- Exported: 2026-08-22T21:54:25.551Z
- Document slug: `ntsb-case-pld24mr005`

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  "jurisdiction": "US",
  "operatorName": "Enbridge Gas Ohio",
  "region": "OH"
}
```
