AL-03-2026

ALERT NOTICE & REQUEST FOR SPECIFIC INFORMATION
MNOPS AL–03-2026 TO PIPELINE OPERATORS NTSB RECOMMENDATIONS FROM PIR-26-01 

Date:

Sept. 10, 2026

Purpose:

The Minnesota Department of Public Safety Office of Pipeline Safety (OPS) is issuing this Alert Notice regarding recommendations from the National Transportation Safety Board (NTSB) in its Pipeline Investigation Report (PIR) 26-01.

In addition, OPS is issuing a request for specific information (RSI) to all intrastate pipeline operators of gas distribution systems pursuant to Minnesota Statute 299F.63 Subdivision (b) and Minnesota Administrative Rules 7530.0400, Subpart 1. Please see the additional information after the alert notice to complete the RSI.

NTSB PIR 26-01: Natural Gas-Fueled Home Explosions and Fires

On Jan. 24, 2024, and Jan. 27, 2024, two natural gas-fueled explosions occurred at two separate residences in Jackson, Mississippi, resulting in one fatality, one injury, and the destruction of three residences. NTSB’s investigation found the following safety issues:

• Mechanical compression fittings that were not resistant to pipe pullout forces in expandable soils
• An insufficient leak management program by the pipeline operator
• An inadequate distribution integrity management program by the pipeline operator
• An ineffective public awareness program by the pipeline operator
• The absence of natural gas detection alarms in buildings

See NTSB’s report, PIR 26-01, regarding this incident.

As a result of NTSB’s investigation, OPS is making the following recommendations to pipeline operators.

1. Consider replacing all mechanical joints that are not resistant to pipe pullout (Reference NTSB Recommendation P-26-003). 

   The following is a summary of facts and details primarily referenced from the NTSB Pipeline Investigation Report PIR-26-01 – Section 1.5 Dresser Style 90 Compression Coupling.

   For the Jackson, MS, incidents, a 2-inch steel natural gas main fed 3/4-inch steel services via a welded saddle on top of the 2-inch steel main, connected to the 3/4-inch steel services by a Dresser Style 90 – seal-only compression coupling. In this case, the seal-only compression coupling was not designed to resist pipe pullout or to keep the pipe in place. Other similar versions of the Dresser Style 90 compression coupling include a clamping design that resists pipe pullout. Operators should consider replacing all Dresser Style 90 – seal-only compression couplings and/or similar mechanical joints that are not resistant to pipe pullout. This recommendation is similar to the advisory bulletin issued by the Pipeline and Hazardous Materials Safety Administration (PHMSA) in 2008. Operators should review this bulletin (Pipeline Safety: Issues Related to Mechanical Couplings Used in Natural Gas Distribution Systems) if they have not already done so.

2. Consider updating leak grading and monitoring procedures to consider the effect of adverse expansive soil conditions and weather on potentially changing non-hazardous leaks to hazardous. Operators should also consider the time required to monitor an area with an active leak, ensuring the residual gas has dissipated to a safe level (Reference NTSB Recommendation P-26-004 and P-26-005). 

   The following is a summary of facts and details primarily referenced from the NTSB Pipeline Investigation Report PIR-26-01 – section 1.3 – Weather and section 1.4 Expansive Soils, but also from other sections of the NTSB report and the Minnesota Building Code 2020 Section 1803.5.3 Expansive Soils.

   The two leaks that caused these events in Jackson, MS, were originally graded by the operator during a leak survey as non-hazardous grade 2 and grade 3, per the Gas Piping Technology Committee standards. The corresponding leak surveys were conducted during a dry-weather period when the soils in the area had dried and contracted. Precipitation was 15.10 inches below the annual average for the year leading up to the incidents. The month prior to the two incidents received 9.48 inches of rainfall, 4.51 inches above normal. The heavy infiltration of water into the existing dry soils caused the soils to expand, placing lateral forces on the mechanical joints, which eventually caused the joints to fail and the leaks to occur. In addition, while natural gas service had not been restored to the area, bar-hole testing conducted two days after the second incident identified residual explosive levels of natural gas around both accident homes.

   The soil around Jackson, MS, is known as “Yazoo” clay, an expansive clay soil that shrinks and swells with changes in ground moisture. Expansive clay soils do exist in Minnesota and are generally defined as fine-grained soils, such as clays and clay-rich silts, with extreme shrink-swell potential and a Plasticity Index of 15 or greater. Operators should consider expansive soils and weather conditions when performing leak grading and monitoring to determine whether a non-hazardous leak could become hazardous over time. Operators should also consider recent water infiltration and the possibility of frost heave during freezing and thawing conditions. Similarly, soil and weather conditions may also affect how an active leak vents. When soils become saturated or frozen, active leaks that previously found paths to the atmosphere may migrate laterally and accumulate to explosive levels near foundations or within structures. Additionally, an operator's procedures should specify that the leak location is deemed safe only when all gas-in-soil readings are at levels below the lower explosive limit.

   Operators should also consider that procedure changes may require staff retraining.

   Resources on expansive soils can be found here:

   Minnesota Building Code 2020 Section 1803.5.3 Expansive Soils
   MNOPS GIS Data for Expandable Soils
   National Geologic Map Database 
   Digital Soil Mapping in MN 

3. Train emergency response officials more frequently and monitor the effectiveness of the training (Reference NTSB Recommendation P-26-006). 

   The following is a summary of facts and details primarily referenced from the NTSB Pipeline Investigation Report PIR-26-01 – section 1.9.2.1.2 – Emergency Response Officials.

   After the two incidents in Jackson, MS, the NTSB’s investigation found that multiple first-response agencies reported receiving insufficient training from the pipeline operator on responding to natural gas incidents and leaks. Operators should consider conducting more frequent face-to-face liaison with public safety answering points (9-1-1 call centers), emergency responders, and public officials. Operators should accurately document these meetings and training sessions to demonstrate compliance with federal regulations.

4. Consider updating emergency response and leak investigation procedures to immediately notify the nearby public of an unrepaired leak that could potentially change over time. Such public notifications should explain what to do if natural gas odorant is smelled, such as evacuating the area, calling 9-1-1, and contacting the pipeline operator (Reference NTSB Recommendation P-26-007).

   The following is a summary of facts and details primarily referenced from the NTSB Pipeline Investigation Report PIR-26-01 – section 1.9.2.2 – Odor Complaints, but also from other sections of the NTSB report.

   During the investigation of these incidents, multiple people approached investigators and described smelling a natural gas odorant before the events. However, they were unaware of what to do when such an event occurred. For one incident location, the homeowner called the pipeline operator on Nov. 20, 2023, three months before the explosion, and reported that he and his wife had continually smelled natural gas odorant around their home in previous months. The operator sent a technician to examine the already-known grade 2 leak and told the homeowner he was “safe” but should call again if he felt it was necessary. The homeowner “took [the operator’s] word for it” that there was no “problem.” The homeowner's wife would later perish in the house explosion.

   Operators should have procedures to notify the public in areas of non-hazardous leaks of the potential for a leak to become hazardous and the warning signs. The notification should specify what steps to take if a leak continues or appears to be worsening, such as safely evacuating the area by moving to a designated safe distance and avoiding ignition sources, calling 9-1-1, and immediately notifying the pipeline operator at their specific emergency number.

5. Operators should consider proactively identifying and collecting missing service-line or other system data for all their operating divisions (Reference NTSB Recommendation P-26-008).

   The following is a summary of facts and details primarily referenced from the NTSB Pipeline Investigation Report PIR-26-01 – section 1.9.3.1 – System Data.

   49th Code of Federal Regulations (CFR) part 192.1007(a)(3) requires an operator to:

   (3) Identify additional information needed and provide a plan for gaining that information over time through normal activities conducted on the pipeline (for example, design, construction, operations or maintenance activities).

   The pipeline operator lacked installation records for 63% of the service lines in its Mississippi division. A total of 193,024 of the 306,387 service lines lacked system data, including the two incident service lines. This consequently affected the operator’s leak management program and risk model because the operator was unaware of locations that required additional leak surveys or posed a higher risk due to compression couplings in expansive soils. Operators should consider whether normal activities on their pipelines are effectively providing the necessary system knowledge for their integrity management plan. In some instances, operators may need to make a more focused approach to gain system knowledge.

6. Distribution pipeline operators should consider the information provided in the 2020 PHMSA report on pipeline risk modeling and also consider transitioning from relative risk models to probabilistic risk models (Reference NTSB Recommendation P-26-009).

   The following is a summary of facts and details primarily referenced from the NTSB Pipeline Investigation Report PIR-26-01 – section 1.9.3.2 – Risk Model.

   In 2020, PHMSA published a report on the strengths and limitations of various pipeline distribution integrity management risk models. These models are qualitative, relative-assessment (index), quantitative, and probabilistic. The report noted that quantitative and probabilistic models are more robust than qualitative and relative-risk models. PHMSA provided the following conclusions in their report:

   (1) Probabilistic risk models were a best practice for large, complex systems and systems lacking data because they were more versatile and provided greater capabilities for risk insights and decision-making support than the other types of models.

   (2) Pipeline operators who continued to use relative-risk models should supplement personnel judgment (subject matter expertise) with as much pipeline physical attribute data (system data) as could reasonably be acquired over time.

   (3) Pipeline operators should take ongoing actions to improve and update (system) data quality and completeness over time.

   Operators should consider the conclusions from PHMSA’s 2020 Pipeline Risk Modeling report and implement changes to their distribution integrity management programs as applicable.

7. Consider making natural gas alarms and resources available to members of the public who live near the operators' pipeline(s) and facilities (Reference NTSB Recommendation P-26-010).

   The following is a summary of facts and details primarily referenced from the NTSB Pipeline Investigation Report PIR-26-01 – section 2.6 – Absence of Natural Gas Detection Alarms in Buildings, but also from other sections of the NTSB report.

   The NTSB reports that in these two incidents, and in many pipeline incidents it has investigated over 50 years, people consistently smell natural gas odorant and either do not know what to do or, when they do, fail to take action to address a potential natural gas emergency.

   Like smoke and carbon monoxide alarms, gas alarms could help alert the public to hazardous leaks. Operators should consider providing natural gas alarm resources to the public living near their pipelines. Operators should also consider demographics that may not detect natural gas odor effectively, such as the elderly, when providing natural gas sensing resources.

OPS urges pipeline operators to review PIR 26-01 and implement the associated recommendations, as applicable.

Request for Specific Information

OPS is issuing a Request for Specific Information (RSI) pursuant to Minnesota Statute 299F.63 Subdivision (b) and Minnesota Administrative Rules 7530.0400, Subpart 1. This request is specific to intrastate pipeline operators who operate gas distribution systems. Please fill out the RSI form online by Nov 6, 2026. Operators with multiple operator identifications (OPID) only need to complete one form but must list all OPIDs on that form in the space provided. Your assigned OPS lead inspector can assist with completing this RSI by selecting that option at the beginning of the form. The information below details what items are being requested so operators can prepare their answers before filling out the form.

Underground compression-style mechanical joints

The following questions are specific to underground compression-style mechanical joints. A compression-style mechanical joint seals and grips pipes by mechanically squeezing a rubber gasket or metal ring around the pipe's exterior utilizing tightening nuts and/or bolts.

• Do any of your underground pipeline systems have compression-style mechanical joints? 
• Does your company have records of existing compression-style mechanical pipeline joint specifications (i.e., make and model) within your underground pipeline systems?
• Are all existing underground compression-style mechanical joints designed to resist pipe pullout?
• Are any of your compression-style mechanical joints Dresser Style 90 compression couplings?

Leak investigation, grading, and monitoring procedures

• Do any of your underground pipeline systems reside within areas of expansive soils? See the resource links provided in item 2 of the alert notice.
• If yes above, do any areas of expansive soils have compression-style mechanical joints in your system?
• Does your company’s leak grading and monitoring procedures consider the effect of adverse expansive soil conditions and weather on potentially changing non-hazardous leaks to hazardous?
• Do your company's procedures require notification to the nearby public of unrepaired leaks that could potentially change over time? If yes, does the procedure specify what the public should do if the smell of natural gas persists or worsens, such as safely evacuating the area, avoiding ignition sources, calling 9-1-1, and contacting your emergency number?
• Do your company’s leak investigation, grading, and/or monitoring procedures account for the effect of how soil and weather conditions may change the venting of an active leak?
• Does your company’s leak investigation procedures consider an area safe only once all gas-in-soil readings are at or below the lower explosive limit?

Training emergency response officials

• How does your company maintain liaison with 9-1-1 call centers and emergency response officials per the requirements of 192.615(c)? 
• Does your company provide training resources to emergency response agencies?

Unknown system data

• Do your pipeline system(s) have unknown or missing data (e.g., unknown pipe or joint material, pipe locations)?
• If yes above, what programs or processes does your company currently have in place to gather this unknown data?
• Are any of the programs or processes above conducted outside of normal pipeline activities such as ground penetrating radar or acoustic emissions?

Distribution integrity management risk models

• Have applicable people within your company reviewed the 2020 PHMSA-published reports regarding the strengths and limitations of various pipeline distribution integrity management risk models?
• What type of risk model does your distribution integrity management program use? 

Gas detection alarms

• Does your company provide gas detection alarms or resources to the public living near your pipeline system(s)? If yes, what specific resources do you provide? 
• Does your company provide any unique resources to the elderly or people with decreased abilities to smell gas odorant living near your pipeline system(s)? If yes, what specific resources do you provide?
• Please provide comments on the viability of regulations requiring the installation of gas detection alarms in certain residential or commercial structures similar to smoke and carbon monoxide alarms. Please include any applicable discussion on steps your company has taken to research gas detection alarms.

Questions or concerns

Thank you for reviewing this alert notice and completing this RSI. Please contact your lead inspector or our main office with any questions or concerns.

Office of Pipeline Safety
651-201-7230
dps.mnops.response@state.mn.us