Incident details
Operator, cause, commodity and consequences with raw source fields.
GD incident on 2017-08-02 — MN
Operator
Centerpoint Energy Resources Corp., Dba Centerpoint Energy Minnesota Gas
Cause
Incorrect Operation
Commodity
Natural Gas
Program
GD
Damage and Injuries
2 fatalities
2 injuries
Property damage (nominal)
$14,622
Incident datetime
2017-08-02 10:22
Report number
Location
MN, HENNEPIN
Narrative
Supplemental update 12/08/2017 - the ntsb preliminary report adopted on august 21, 2017 publicly describes the event as follows: on august 2, 2017, at 10:22 a.M., a building at the minnehaha academy (north campus) in minneapolis, minnesota, was destroyed by a natural gas explosion. [reference to figure removed] as a result of the explosion, two individuals were killed and nine were injured. At the time of the explosion, two workers were installing new piping to support the relocation of gas meters from the basement of the building to the outside. Two new meters mounted on a wall were ready for the new piping to be connected. While workers were removing the existing piping, a full-flow natural gas line at pressure was opened. The workers were unable to mitigate the release of the gas, so they evacuated the area. Https://www.Ntsb.Gov/investigations/accidentreports/pages/dca17mp007-prelim-report.Aspx final update as of 1/21/2020 on december 4, 2019, the ntsb released the public docket for its investigation into the incident. As described in the documents included in the public docket, the ntsb found that the release of natural gas at minnehaha academy occurred when master mechanical disassembled existing piping in the academy's boiler room. The master mechanical personnel believed a 3-inch walworth plug valve upstream of the disassembled existing piping was in the closed position on the day of the explosion, when in fact it was open. The ntsb also performed a post-incident analysis of evidence taken from the scene of the explosion and found that indicators on the 3-inch walworth plug valve confirmed that the valve's orientation was in the open position. The ntsb also noted that "confirmation of whether the valve is open or closed is the responsibility of the crew working on the piping. This confirmation would entail removal of the handle and noting the position of the plug assembly." the master mechanical personnel did not perform either of these functions to confirm the orientation of the valve on the day of the explosion. As noted in pard d 2a of this report, the explosion caused an estimated $48 million in "property damage" (as defined in PHMSA f7100.1) to the school. This figure is based on estimates from the school and the school's property insurer. In its december 6, 2019 accident brief, the ntsb stated that "the probable cause of the natural gas explosion at the minnehaha academy was the disassembling of piping upstream of a gas service meter in the building by a pipefitting crew [master mechanical], resulting in the release of natural gas, which subsequently ignited. Contributing to the accident was the lack of detailed documentation that clearly established the scope of work to be performed."
Detailed record list
Occurred At
2017-08-02 10:22:00
Year
2017
Report Received Date
2017-12-05 00:00:00
Iyear
2017.0
Report Number
20170111.0
Supplemental Number
33303.0
Report Type
Supplemental Final
Operator Id
12350
Name
Centerpoint Energy Resources Corp., Dba Centerpoint Energy Minnesota Gas
Operator Street Address
1111 Louisiana St
Operator City Name
Houston
Operator State Abbreviation
TX
Operator Postal Code
77002
Local Datetime
2017-08-02 10:22:00
Location Street Address
3100 W. River Parkway
Location City Name
Minneapolis
Location County Name
Hennepin
Location State Abbreviation
MN
Location Postal Code
55406
Location Latitude
44.946042
Location Longitude
-93.205926
Nrc Rpt Datetime
2017-08-02 12:06:00
Nrc Rpt Num
1186035
Commodity Released Type
Natural Gas
Unintentional Release
0.0
Fatality Ind
Yes
Num Emp Fatalities
0
Num Contr Fatalities
0
Num Er Fatalities
0
Num Worker Fatalities
0
Num Gp Fatalities
2
Fatal
2
Injury Ind
Yes
Num Emp Injuries
0
Num Contr Injuries
1
Num Er Injuries
0
Num Worker Injuries
0
Num Gp Injuries
1
Injure
2
Ignite Ind
Yes
Explode Ind
Yes
Num Pub Evacuated
45.0
Incident Identified Datetime
2017-08-02 10:22:00
On Site Datetime
2017-08-02 10:25:00
Federal
No
Location Type
Private Property
Incident Area Type
Transition Area
Incident Area Subtype
Other
Incident Area Details
Basement/ Meter Room
Crossing
No
Pipe Facility Type
Investor Owned
System Part Involved
Inside Meter/regulator Set
Installation Year
1959.0
Material Involved
Steel
Release Type
Other
Release Type Details
Live Gas Piping Was Disassembled.
Class Location Type
Class 3 Location
Est Cost Oper Paid
48000000.0
Est Cost Prop Damage
14622.0
Est Cost Emergency
8807.0
Est Cost Other
0.0
Est Cost Unintentional Release
0.0
Prpty
48023429.0
Commercial Affected
1.0
Industrial Affected
0.0
Residences Affected
0.0
Accident Psig
10.0
Normal Psig
10.0
Mop Psig
15.0
Accident Pressure
Pressure Did Not Exceed Maop
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
Yes
Num Contractors Tested
2
Num Contractors Failed
0
Cause
Incorrect Operation
Cause Details
Other Incorrect Operation
Operation Type
Other Incorrect Operation
Operation Details
Knowing That The Gas Was Still On To The Building, Master Mechanical's Journeyman/pipefitter Failed To Recognize That Centerpoint Energy's Jurisdictional Valve Was In The Open Position Before He And His Master Mechanical Helper Disassembled Piping. The Master Mechanical Personnel Also Failed To Purge The Jurisdictional Piping Downstream Of The Valve.
Related Other Ind
Yes
Operation Related Details
Per Master Mechanical's Bid For The Work At Minnehaha Academy, Master Mechanical Was Hired To Only Work On Non-Jurisdictional Customer Piping. Work On Jurisdictional Equipment, Including The Piping That Master Mechanical Ultimately Disassembled, Was Not Within Their Scope Of Work, And Centerpoint Energy Did Not Request They Work On Jurisdictional Equipment. Master Mechanical's Unauthorized Work On Jurisdictional Piping Upstream Of The Gas Meter Led To The Gas Release That Caused The Incident.
Category Type
Other Maintenance
Operator Qualification Ind
No
Preparer Name
A**** A*********
Preparer Title
Operations Specialist Ii
Preparer Email
A***************@c****************.com
Preparer Telephone
6123215514
Authorizer Name
D*** H******
Authorizer Title
Manager Of Pipeline Safety And Compliance
Authorizer Telephone
6123215366
Authorizer Email
D***********@c****************.com
Narrative
Supplemental update 12/08/2017 - the ntsb preliminary report adopted on august 21, 2017 publicly describes the event as follows: on august 2, 2017, at 10:22 a.M., a building at the minnehaha academy (north campus) in minneapolis, minnesota, was destroyed by a natural gas explosion. [reference to figure removed] as a result of the explosion, two individuals were killed and nine were injured. At the time of the explosion, two workers were installing new piping to support the relocation of gas meters from the basement of the building to the outside. Two new meters mounted on a wall were ready for the new piping to be connected. While workers were removing the existing piping, a full-flow natural gas line at pressure was opened. The workers were unable to mitigate the release of the gas, so they evacuated the area. Https://www.Ntsb.Gov/investigations/accidentreports/pages/dca17mp007-prelim-report.Aspx final update as of 1/21/2020 on december 4, 2019, the ntsb released the public docket for its investigation into the incident. As described in the documents included in the public docket, the ntsb found that the release of natural gas at minnehaha academy occurred when master mechanical disassembled existing piping in the academy's boiler room. The master mechanical personnel believed a 3-inch walworth plug valve upstream of the disassembled existing piping was in the closed position on the day of the explosion, when in fact it was open. The ntsb also performed a post-incident analysis of evidence taken from the scene of the explosion and found that indicators on the 3-inch walworth plug valve confirmed that the valve's orientation was in the open position. The ntsb also noted that "confirmation of whether the valve is open or closed is the responsibility of the crew working on the piping. This confirmation would entail removal of the handle and noting the position of the plug assembly." the master mechanical personnel did not perform either of these functions to confirm the orientation of the valve on the day of the explosion. As noted in pard d 2a of this report, the explosion caused an estimated $48 million in "property damage" (as defined in PHMSA f7100.1) to the school. This figure is based on estimates from the school and the school's property insurer. In its december 6, 2019 accident brief, the ntsb stated that "the probable cause of the natural gas explosion at the minnehaha academy was the disassembling of piping upstream of a gas service meter in the building by a pipefitting crew [master mechanical], resulting in the release of natural gas, which subsequently ignited. Contributing to the accident was the lack of detailed documentation that clearly established the scope of work to be performed."
| Occurred At | 2017-08-02 10:22:00 |
|---|---|
| Year | 2017 |
| Report Received Date | 2017-12-05 00:00:00 |
| Iyear | 2017.0 |
| Report Number | 20170111.0 |
| Supplemental Number | 33303.0 |
| Report Type | Supplemental Final |
| Operator Id | 12350 PHMSA Enforcement |
| Name | Centerpoint Energy Resources Corp., Dba Centerpoint Energy Minnesota Gas |
| Operator Street Address | 1111 Louisiana St |
| Operator City Name | Houston |
| Operator State Abbreviation | TX |
| Operator Postal Code | 77002 |
| Local Datetime | 2017-08-02 10:22:00 |
| Location Street Address | 3100 W. River Parkway |
| Location City Name | Minneapolis |
| Location County Name | Hennepin |
| Location State Abbreviation | MN |
| Location Postal Code | 55406 |
| Location Latitude | 44.946042 Google Maps OpenStreetMap |
| Location Longitude | -93.205926 Google Maps OpenStreetMap |
| Nrc Rpt Datetime | 2017-08-02 12:06:00 |
| Nrc Rpt Num | 1186035 NRC Report How to search |
| Commodity Released Type | Natural Gas |
| Unintentional Release | 0.0 |
| Fatality Ind | Yes |
| Num Emp Fatalities | 0 |
| Num Contr Fatalities | 0 |
| Num Er Fatalities | 0 |
| Num Worker Fatalities | 0 |
| Num Gp Fatalities | 2 |
| Fatal | 2 |
| Injury Ind | Yes |
| Num Emp Injuries | 0 |
| Num Contr Injuries | 1 |
| Num Er Injuries | 0 |
| Num Worker Injuries | 0 |
| Num Gp Injuries | 1 |
| Injure | 2 |
| Ignite Ind | Yes |
| Explode Ind | Yes |
| Num Pub Evacuated | 45.0 |
| Incident Identified Datetime | 2017-08-02 10:22:00 |
| On Site Datetime | 2017-08-02 10:25:00 |
| Federal | No |
| Location Type | Private Property |
| Incident Area Type | Transition Area |
| Incident Area Subtype | Other |
| Incident Area Details | Basement/ Meter Room |
| Crossing | No |
| Pipe Facility Type | Investor Owned |
| System Part Involved | Inside Meter/regulator Set |
| Installation Year | 1959.0 |
| Material Involved | Steel |
| Release Type | Other |
| Release Type Details | Live Gas Piping Was Disassembled. |
| Class Location Type | Class 3 Location |
| Est Cost Oper Paid | 48000000.0 |
| Est Cost Prop Damage | 14622.0 |
| Est Cost Emergency | 8807.0 |
| Est Cost Other | 0.0 |
| Est Cost Unintentional Release | 0.0 |
| Prpty | 48023429.0 |
| Commercial Affected | 1.0 |
| Industrial Affected | 0.0 |
| Residences Affected | 0.0 |
| Accident Psig | 10.0 |
| Normal Psig | 10.0 |
| Mop Psig | 15.0 |
| Accident Pressure | Pressure Did Not Exceed Maop |
| 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 | Yes |
| Num Contractors Tested | 2 |
| Num Contractors Failed | 0 |
| Cause | Incorrect Operation |
| Cause Details | Other Incorrect Operation |
| Operation Type | Other Incorrect Operation |
| Operation Details | Knowing That The Gas Was Still On To The Building, Master Mechanical's Journeyman/pipefitter Failed To Recognize That Centerpoint Energy's Jurisdictional Valve Was In The Open Position Before He And His Master Mechanical Helper Disassembled Piping. The Master Mechanical Personnel Also Failed To Purge The Jurisdictional Piping Downstream Of The Valve. |
| Related Other Ind | Yes |
| Operation Related Details | Per Master Mechanical's Bid For The Work At Minnehaha Academy, Master Mechanical Was Hired To Only Work On Non-Jurisdictional Customer Piping. Work On Jurisdictional Equipment, Including The Piping That Master Mechanical Ultimately Disassembled, Was Not Within Their Scope Of Work, And Centerpoint Energy Did Not Request They Work On Jurisdictional Equipment. Master Mechanical's Unauthorized Work On Jurisdictional Piping Upstream Of The Gas Meter Led To The Gas Release That Caused The Incident. |
| Category Type | Other Maintenance |
| Operator Qualification Ind | No |
| Preparer Name | A**** A********* |
| Preparer Title | Operations Specialist Ii |
| Preparer Email | A***************@c****************.com |
| Preparer Telephone | 6123215514 |
| Authorizer Name | D*** H****** |
| Authorizer Title | Manager Of Pipeline Safety And Compliance |
| Authorizer Telephone | 6123215366 |
| Authorizer Email | D***********@c****************.com |
| Narrative | Supplemental update 12/08/2017 - the ntsb preliminary report adopted on august 21, 2017 publicly describes the event as follows: on august 2, 2017, at 10:22 a.M., a building at the minnehaha academy (north campus) in minneapolis, minnesota, was destroyed by a natural gas explosion. [reference to figure removed] as a result of the explosion, two individuals were killed and nine were injured. At the time of the explosion, two workers were installing new piping to support the relocation of gas meters from the basement of the building to the outside. Two new meters mounted on a wall were ready for the new piping to be connected. While workers were removing the existing piping, a full-flow natural gas line at pressure was opened. The workers were unable to mitigate the release of the gas, so they evacuated the area. Https://www.Ntsb.Gov/investigations/accidentreports/pages/dca17mp007-prelim-report.Aspx final update as of 1/21/2020 on december 4, 2019, the ntsb released the public docket for its investigation into the incident. As described in the documents included in the public docket, the ntsb found that the release of natural gas at minnehaha academy occurred when master mechanical disassembled existing piping in the academy's boiler room. The master mechanical personnel believed a 3-inch walworth plug valve upstream of the disassembled existing piping was in the closed position on the day of the explosion, when in fact it was open. The ntsb also performed a post-incident analysis of evidence taken from the scene of the explosion and found that indicators on the 3-inch walworth plug valve confirmed that the valve's orientation was in the open position. The ntsb also noted that "confirmation of whether the valve is open or closed is the responsibility of the crew working on the piping. This confirmation would entail removal of the handle and noting the position of the plug assembly." the master mechanical personnel did not perform either of these functions to confirm the orientation of the valve on the day of the explosion. As noted in pard d 2a of this report, the explosion caused an estimated $48 million in "property damage" (as defined in PHMSA f7100.1) to the school. This figure is based on estimates from the school and the school's property insurer. In its december 6, 2019 accident brief, the ntsb stated that "the probable cause of the natural gas explosion at the minnehaha academy was the disassembling of piping upstream of a gas service meter in the building by a pipefitting crew [master mechanical], resulting in the release of natural gas, which subsequently ignited. Contributing to the accident was the lack of detailed documentation that clearly established the scope of work to be performed." |
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