Incident details
Operator, cause, commodity and consequences with raw source fields.
GD incident on 2024-02-15 — MT
Operator
Northwestern Corporation
Cause
Natural Force Damage
Commodity
Natural Gas
Program
GD
Damage and Injuries
0 fatalities
0 injuries
Property damage (nominal)
$2,500
Incident datetime
2024-02-15 00:00 UTC
Report number
Location
MT, MISSOULA
Narrative
A7 - unable to determine as time pipe has been leaking is unknown 21c - no additional gas was released beyond underground pipe leaking for unknown amount of time part c 4.A. - educated guess due to age of pipe timeline of events prior to explosion: 10:35 am: received odor call for 1342 s. 5th st w 10:52 am: arrived at the site of the odor call 1342 s. 5th st w worked inside, checking appliances, venting, ambient checked outside ambient, meter set, bar holed along service 11:30 am: requested additional help with leak surveying 11:36 am: gas supervisor informing about active leak, under investigation 11:42 - 11:48 am: emergency locates requested 11:50 am: additional help arrived onsite and began to monitor ambient, survey surroundings, mapping 12:00 pm: notified missoula fire department (mfd), gas leak, requested fd to be dispatched begin evacuating homes 12:04 pm: de-energized power @ 1410 a/b s. 5th st w. Mfd assistance checking ambient inside homes 12:36 pm: de-energized secondary power to 1410 a/b s. 5th st w. 12:36 - 12: 48 pm: begun barholing prior 12:48 pm: requested backhoe to assist with barholing 12:50 pm: house explosion post explosion: 12:50pm: 1413 s. 4th st w house explosion 12:50 pm: de-energize primary for multiple blocks from russell & 5th ' east (four blocks east) mfd - increased perimeter continued evacuations, road closures, fire ic dave any injuries resulted: his response no one was home, no injuries 1:05 pm: de-energized primary russell & 5th ' east (four blocks east) 1:10 pm: additional support arrived onsite. Informed fire ic dave ' of plan to operate zv # 24, to eliminate gas flow from east and install pressure control fitting (pcf) to eliminate gas flow from west 1:39 pm zone valve # 24 stopping feed from the east. 1:40 pm: began bellhole excavation at 1501 s. 4th st w alley 2:00 pm: began shutting off all lockwing valves 2:15 pm: mfd shut off lockwing valve to 1413 s. 4th st w 4:00 pm: pcf # 1 pilot bit broke (west of russell) 4:00 pm: began pcf # 2 (west of russell) 5:10 pm: pcf # 2 stoppered, feed from west was shut off. 5:15 pm: gas successful stopped.Confirmed feed from west was shut off by breaking down meter set at 1501 s. 4th st w. 5:15 pm to 1 am: continued barholing, ambient monitoring, turned off all the lockwing valves east of prince. Restoration efforts completed in the follow day. Update 5-7-2025 on june 3, 2024 destructive testing was conducted at material evaluation and engineering. Enclosed is the testing protocol utilized to destructively test the pipe removed from event in missoula, mt on january 17, 2024. The following tests were conducted. 'chemistry identification (astm e415-2021) energy dispersive x-ray spectroscopy (eds) keyence microhardness rockwell harness scanning electron microscopy (sem) xs results indicated a singular immediate (not over time) facture consistent with the pipe coming up. Given the direction of the fracture something below the pipe caused the surface to change/rise up to create the fracture.
Detailed record list
Report Received Date
2024-02-15 00:00:00
Iyear
2024.0
Report Number
20240009.0
Supplemental Number
40853.0
Report Type
Supplemental
Operator Id
31632
Name
Northwestern Corporation
Operator Street Address
3010 W. 69th St.
Operator City Name
Sioux Falls
Operator State Abbreviation
SD
Operator Postal Code
57108.0
Time Zone
Mountain
Daylight Savings Ind
Yes
Location Street Address
1413 S 4th St. W
Location City Name
Missoula
Location County Name
Missoula
Location State Abbreviation
MT
Location Postal Code
59801.0
Location Latitude
46.86573
Location Longitude
-114.01772
Flow Cont Key Crit Ind
Yes
Nrc Rpt Num
1389218.0
Additional Nrc Report Numbers
1389458.0
Commodity Released Type
Natural Gas
Unintentional Release
16.28
Intentional Release
0.0
Fatality Ind
No
Fatal
0
Injury Ind
No
Injure
0
Ignite Ind
Yes
How Extinguished
Local/state/federal Emergency Responder
Gas Consumed By Fire In Mcf
0
Explode Ind
Yes
Num Pub Evacuated
50.0
Communication State Fed Ind
Yes
Party Initiated Communication
Operator
Federal
No
Location Type
Public Property
Incident Area Type
Underground
Incident Area Subtype
Under Pavement
Depth Of Cover
38.0
Other Underground Facilities
No
Crossing
No
Pipe Facility Type
Investor Owned
System Part Involved
Main
Pipe Diameter
3.625
Pipe Specification
Unknown
Pipe Manufacturer
Unknown
Material Involved
Steel
Steel Seam Type
Longitudinal Erw - Low Frequency
Wt Steel
0.322
Release Type
Leak
Leak Type
Crack
Class Location Type
Class 3 Location
Est Cost Oper Paid
400000.0
Est Cost Prop Damage
2500.0
Est Cost Emergency
10000.0
Est Cost Other
0.0
Gas Cost In Mcf
9.0
Est Cost Unintentional Release
147.0
Est Cost Intentional Release
0.0
Prpty
412647.0
Commercial Affected
4.0
Industrial Affected
0.0
Residences Affected
46.0
Num Persons Hosp Not Ovnght
0.0
Num Injured Treated By Emt
0.0
Num Resident Building Affctd
46.0
Num Business Building Affctd
4.0
Accident Psig
31.0
Normal Psig
31.0
Mop Psig
35.0
Mop Cfr Section
192.619(A)(4)
Maop Established Date
1995-01-26 00:00:00
Accident Pressure
Pressure Did Not Exceed Maop
Gas Odorized System Type
Injection Pump
Gas Odorized Level
3
Scada In Place Ind
No
Accident Identifier
Local Operating Personnel, Including Contractors
Operator Type
Operator Employee
Investigation Status
No, the facility was not monitored by a controller(s) at the time of the incident
Employee Drug Test Ind
No
Contractor Drug Test Ind
No
Cause
Natural Force Damage
Cause Details
Temperature
Natural Force Type
Temperature
Temperature Subtype
Frost Heave
Nf Extreme Weather Ind
No
Preparer Name
M****** B*****
Preparer Title
Supervisor Dot
Preparer Email
M*************@n***********.com
Preparer Telephone
6053537462
Authorizer Name
M****** B*****
Authorizer Title
Dot Supervisor
Authorizer Telephone
605-353-7462
Authorizer Email
M*************@n***********.com
Narrative
A****************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************@ 1410 a/b s. 5th st w. Mfd assistance checking ambient inside homes 12:36 pm: de-energized secondary power to 1410 a/b s. 5th st w. 12:36 - 12: 48 pm: begun barholing prior 12:48 pm: requested backhoe to assist with barholing 12:50 pm: house explosion post explosion: 12:50pm: 1413 s. 4th st w house explosion 12:50 pm: de-energize primary for multiple blocks from russell & 5th ' east (four blocks east) mfd - increased perimeter continued evacuations, road closures, fire ic dave any injuries resulted: his response no one was home, no injuries 1:05 pm: de-energized primary russell & 5th ' east (four blocks east) 1:10 pm: additional support arrived onsite. Informed fire ic dave ' of plan to operate zv # 24, to eliminate gas flow from east and install pressure control fitting (pcf) to eliminate gas flow from west 1:39 pm zone valve # 24 stopping feed from the east. 1:40 pm: began bellhole excavation at 1501 s. 4th st w alley 2:00 pm: began shutting off all lockwing valves 2:15 pm: mfd shut off lockwing valve to 1413 s. 4th st w 4:00 pm: pcf # 1 pilot bit broke (west of russell) 4:00 pm: began pcf # 2 (west of russell) 5:10 pm: pcf # 2 stoppered, feed from west was shut off. 5:15 pm: gas successful stopped.Confirmed feed from west was shut off by breaking down meter set at 1501 s. 4th st w. 5:15 pm to 1 am: continued barholing, ambient monitoring, turned off all the lockwing valves east of prince. Restoration efforts completed in the follow day. Update 5-7-2025 on june 3, 2024 destructive testing was conducted at material evaluation and engineering. Enclosed is the testing protocol utilized to destructively test the pipe removed from event in missoula, mt on january 17, 2024. The following tests were conducted. 'chemistry identification (astm e415-2021) energy dispersive x-ray spectroscopy (eds) keyence microhardness rockwell harness scanning electron microscopy (sem) xs results indicated a singular immediate (not over time) facture consistent with the pipe coming up. *************************************************************************************************************************.
| Report Received Date | 2024-02-15 00:00:00 |
|---|---|
| Iyear | 2024.0 |
| Report Number | 20240009.0 |
| Supplemental Number | 40853.0 |
| Report Type | Supplemental |
| Operator Id | 31632 PHMSA Enforcement |
| Name | Northwestern Corporation |
| Operator Street Address | 3010 W. 69th St. |
| Operator City Name | Sioux Falls |
| Operator State Abbreviation | SD |
| Operator Postal Code | 57108.0 |
| Time Zone | Mountain |
| Daylight Savings Ind | Yes |
| Location Street Address | 1413 S 4th St. W |
| Location City Name | Missoula |
| Location County Name | Missoula |
| Location State Abbreviation | MT |
| Location Postal Code | 59801.0 |
| Location Latitude | 46.86573 Google Maps OpenStreetMap |
| Location Longitude | -114.01772 Google Maps OpenStreetMap |
| Flow Cont Key Crit Ind | Yes |
| Nrc Rpt Num | 1389218.0 NRC Report How to search |
| Additional Nrc Report Numbers | 1389458.0 |
| Commodity Released Type | Natural Gas |
| Unintentional Release | 16.28 |
| Intentional Release | 0.0 |
| Fatality Ind | No |
| Fatal | 0 |
| Injury Ind | No |
| Injure | 0 |
| Ignite Ind | Yes |
| How Extinguished | Local/state/federal Emergency Responder |
| Gas Consumed By Fire In Mcf | 0 |
| Explode Ind | Yes |
| Num Pub Evacuated | 50.0 |
| Communication State Fed Ind | Yes |
| Party Initiated Communication | Operator |
| Federal | No |
| Location Type | Public Property |
| Incident Area Type | Underground |
| Incident Area Subtype | Under Pavement |
| Depth Of Cover | 38.0 |
| Other Underground Facilities | No |
| Crossing | No |
| Pipe Facility Type | Investor Owned |
| System Part Involved | Main |
| Pipe Diameter | 3.625 |
| Pipe Specification | Unknown |
| Pipe Manufacturer | Unknown |
| Material Involved | Steel |
| Steel Seam Type | Longitudinal Erw - Low Frequency |
| Wt Steel | 0.322 |
| Release Type | Leak |
| Leak Type | Crack |
| Class Location Type | Class 3 Location |
| Est Cost Oper Paid | 400000.0 |
| Est Cost Prop Damage | 2500.0 |
| Est Cost Emergency | 10000.0 |
| Est Cost Other | 0.0 |
| Gas Cost In Mcf | 9.0 |
| Est Cost Unintentional Release | 147.0 |
| Est Cost Intentional Release | 0.0 |
| Prpty | 412647.0 |
| Commercial Affected | 4.0 |
| Industrial Affected | 0.0 |
| Residences Affected | 46.0 |
| Num Persons Hosp Not Ovnght | 0.0 |
| Num Injured Treated By Emt | 0.0 |
| Num Resident Building Affctd | 46.0 |
| Num Business Building Affctd | 4.0 |
| Accident Psig | 31.0 |
| Normal Psig | 31.0 |
| Mop Psig | 35.0 |
| Mop Cfr Section | 192.619(A)(4) View CFR 49 §192 |
| Maop Established Date | 1995-01-26 00:00:00 |
| Accident Pressure | Pressure Did Not Exceed Maop |
| Gas Odorized System Type | Injection Pump |
| Gas Odorized Level | 3 |
| Scada In Place Ind | No |
| Accident Identifier | Local Operating Personnel, Including Contractors |
| Operator Type | Operator Employee |
| Investigation Status | No, the facility was not monitored by a controller(s) at the time of the incident |
| Employee Drug Test Ind | No |
| Contractor Drug Test Ind | No |
| Cause | Natural Force Damage |
| Cause Details | Temperature |
| Natural Force Type | Temperature |
| Temperature Subtype | Frost Heave |
| Nf Extreme Weather Ind | No |
| Preparer Name | M****** B***** |
| Preparer Title | Supervisor Dot |
| Preparer Email | M*************@n***********.com |
| Preparer Telephone | 6053537462 |
| Authorizer Name | M****** B***** |
| Authorizer Title | Dot Supervisor |
| Authorizer Telephone | 605-353-7462 |
| Authorizer Email | M*************@n***********.com |
| Narrative | A****************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************@ 1410 a/b s. 5th st w. Mfd assistance checking ambient inside homes 12:36 pm: de-energized secondary power to 1410 a/b s. 5th st w. 12:36 - 12: 48 pm: begun barholing prior 12:48 pm: requested backhoe to assist with barholing 12:50 pm: house explosion post explosion: 12:50pm: 1413 s. 4th st w house explosion 12:50 pm: de-energize primary for multiple blocks from russell & 5th ' east (four blocks east) mfd - increased perimeter continued evacuations, road closures, fire ic dave any injuries resulted: his response no one was home, no injuries 1:05 pm: de-energized primary russell & 5th ' east (four blocks east) 1:10 pm: additional support arrived onsite. Informed fire ic dave ' of plan to operate zv # 24, to eliminate gas flow from east and install pressure control fitting (pcf) to eliminate gas flow from west 1:39 pm zone valve # 24 stopping feed from the east. 1:40 pm: began bellhole excavation at 1501 s. 4th st w alley 2:00 pm: began shutting off all lockwing valves 2:15 pm: mfd shut off lockwing valve to 1413 s. 4th st w 4:00 pm: pcf # 1 pilot bit broke (west of russell) 4:00 pm: began pcf # 2 (west of russell) 5:10 pm: pcf # 2 stoppered, feed from west was shut off. 5:15 pm: gas successful stopped.Confirmed feed from west was shut off by breaking down meter set at 1501 s. 4th st w. 5:15 pm to 1 am: continued barholing, ambient monitoring, turned off all the lockwing valves east of prince. Restoration efforts completed in the follow day. Update 5-7-2025 on june 3, 2024 destructive testing was conducted at material evaluation and engineering. Enclosed is the testing protocol utilized to destructively test the pipe removed from event in missoula, mt on january 17, 2024. The following tests were conducted. 'chemistry identification (astm e415-2021) energy dispersive x-ray spectroscopy (eds) keyence microhardness rockwell harness scanning electron microscopy (sem) xs results indicated a singular immediate (not over time) facture consistent with the pipe coming up. *************************************************************************************************************************. |
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