Campus Alert Archive
UMN

Six Athletic Buildings — Williams Arena, Huntington Bank Stadium, the Aquatics Center — Evacuated After Sewer-Tunnel Petroleum Vapors Reached the Lower Explosive Limit

MNhazmatemergency notificationmedium confidence
Confirmed Threat

On Tuesday morning, August 2, 2022, Met Council contractors working in a sewer tunnel near 5th Street and Oak Street SE at the University of Minnesota Twin Cities reported their gas monitors had sounded an alarm and that they could see and smell petroleum in the tunnel. Some readings reached the lower explosive limit. Minneapolis Fire was on scene by approximately 11:30 AM CDT. UMN's SAFE-U emergency notification system pushed evacuation orders covering Williams Arena, Huntington Bank Stadium, McNamara Alumni Center, the Aquatics Center, the Recreation and Wellness Center, and the Mariucci and Maturi Sports Pavilion. The Minnesota Department of Public Safety later determined the substance was diesel fuel. The evacuation order was lifted at approximately 4:30 PM CDT.

Alerts
3
Response
min
Killed
0
Injured
0
Institution
University of Minnesota Twin Cities
Public R1 · MN
~54,000 studentsSAFE-U
Confirmed Timeline

Alert Sequence

3 messages in sequence

Some alert texts below are approximate reconstructions from news coverage, not confirmed verbatim transcripts. Reconstructed texts are shown in italic with a dashed border. Verified verbatim texts have a solid border and are marked accordingly.

INITIAL ALERTSMS
Approximate reconstructionReconstructed from MPR News and the Minnesota Daily reporting that summarized the SAFE-U notification's evacuation list; the verbatim text was not preserved in the archive207 chars
SAFE-U EMERGENCY: Possible gas leak in area of Williams Arena. Evacuate Williams Arena, Huntington Bank Stadium, McNamara, Aquatics Center, Recreation Center, Mariucci and Maturi Sports Pavilion immediately.

This text has been reconstructed from news coverage and may not reflect the exact original wording.

Reconstructed from MPR News and Minnesota Daily reporting; the verbatim SAFE-U text was not preserved publicly, but the six-building evacuation list and 'possible gas leak in area of Williams Arena' framing are quoted directly across reporting.
Pushed late morning August 2, 2022, around the time Minneapolis Fire arrived at the Met Council sewer tunnel at 5th Street and Oak Street SE.
SAFE-U's 'EMERGENCY' prefix is the system's highest-tier signal — distinct from the lower-tier SAFE-U Advisory used for crime alerts and weather watches.
UPDATESMS
Approximate reconstructionReconstructed from Minnesota Daily live coverage and KSTP reporting on the continuing evacuation through the afternoon269 chars
SAFE-U UPDATE: Minneapolis Fire continues to investigate the suspected petroleum leak in the sewer system. Evacuation orders remain in effect for Williams Arena, Huntington Bank Stadium, McNamara, Aquatics Center, Recreation Center, Mariucci and Maturi Sports Pavilion.

This text has been reconstructed from news coverage and may not reflect the exact original wording.

Verbatim follow-up text not preserved in archive; reconstructed from Minnesota Daily and KSTP reporting that the SAFE-U evacuation order remained in effect through the afternoon.
Minneapolis Fire ultimately washed out the sewer line to flush the petroleum, the same mitigation technique they had used 33 days earlier after the June 30, 2022 sewer-gasoline explosion that blew manhole covers across University Avenue.
Some petroleum-vapor readings in the tunnel reached the 'lower explosive limit,' the lowest concentration at which the vapor will burn in air — meaning a brief window during which the sewer system could have ignited a second time.
ALL CLEARSMS
Approximate reconstructionReconstructed from KSTP and Star Tribune reporting that the evacuation order was lifted around 4:30 PM192 chars
SAFE-U ALL CLEAR: Evacuation orders are lifted. Williams Arena, Huntington Bank Stadium, McNamara, Aquatics Center, Recreation Center, Mariucci and Maturi Sports Pavilion are safe to re-enter.

This text has been reconstructed from news coverage and may not reflect the exact original wording.

Verbatim all-clear text not preserved in archive; reconstructed from KSTP and Star Tribune coverage that the evacuation order was lifted at approximately 4:30 PM CDT.
The Minnesota Department of Public Safety later identified the substance as diesel fuel; the source of the spill remained unknown at the time of the all-clear.
End-to-end evacuation lasted approximately five hours, from late-morning notification through the 4:30 PM all-clear.
Context

Background

On the late morning of Tuesday, August 2, 2022, Met Council contractors working in the sewer tunnel located at 5th Street and Oak Street SE on the University of Minnesota Twin Cities campus reported their gas monitors had sounded an alarm and that they could see and smell petroleum in the tunnel — some readings reached the lower explosive limit. Minneapolis Fire was on scene by approximately 11:30 AM CDT. UMN's SAFE-U emergency notification system pushed evacuation orders covering an unusually large athletic-facility footprint: Williams Arena, Huntington Bank Stadium, McNamara Alumni Center, the Aquatics Center, the Recreation and Wellness Center, and the Mariucci and Maturi Sports Pavilion. The Minnesota Department of Public Safety later determined the substance was diesel fuel, though the source of the spill remained unknown. Fire crews flushed the sewer system, and the evacuation order was lifted at approximately 4:30 PM CDT after readings returned to normal. This incident occurred just 33 days after the June 30, 2022 sewer-gasoline explosion that blew manhole covers off University Avenue near a Delta Tau Delta fraternity-house fire — making the August 2 evacuation the second major sewer-fuel incident on UMN's Twin Cities campus in just over a month, prompting renewed questions about whether the two events shared a single underlying source of fuel entering the campus sewer system.
Analysis

Key Findings

SAFE-U's evacuation push covered an unusually large athletic-facility footprint — six major buildings including Williams Arena and Huntington Bank Stadium — during a single coordinated emergency.
The August 2 diesel-fuel evacuation came just 33 days after UMN's June 30 sewer-gasoline explosion, the second time in five weeks that petroleum vapors in campus sewer lines reached dangerous concentrations.
Sewer-tunnel vapor readings reached the lower explosive limit — meaning a brief window during which a single ignition source could have triggered a second sewer-system explosion in five weeks.
Outcome
Evacuation order lifted at approximately 4:30 PM CDT on August 2, 2022 after air and water quality readings returned to normal following sewer-system flushing. The Minnesota Department of Public Safety determined the substance was diesel fuel; the source of the spill remained unknown at the time of the all-clear. No injuries reported. This was the second major sewer-fuel evacuation on UMN's Twin Cities campus in 33 days, following the June 30, 2022 gasoline-sewer explosion that blew manhole covers off University Avenue.
Provenance

Sources

  1. News
    Petroleum leak forces evacuations on U Twin Cities campus (MPR News)
    mprnews.org
  2. News
    Evacuation orders near U of M lifted as gas levels return to normal (KSTP)
    kstp.com
  3. News
    Evacuation order lifted on UMN campus following petroleum leak (CBS Minnesota)
    cbsnews.com
  4. News
    University of Minnesota evacuation orders lifted after gas spill (KARE 11)
    kare11.com
  5. Student Paper
    BREAKING: Confirmed petroleum leak, firefighters evacuate UMN buildings (The Minnesota Daily)
    mndaily.com
  6. News
    Evacuation orders lifted after gasoline leak at University of Minnesota athletic sites (Star Tribune)
    startribune.com
  7. Official
    Twin Cities Campus: SAFE-U Emergency (UMN Safe Campus)
    safe-campus.umn.edu
  8. Official
    SAFE-U EMERGENCY (UMN Department of Public Safety)
    publicsafety.umn.edu
Tags
MinnesotaUniversity of MinnesotaSAFE-Uhazmatpetroleumdiesel-fuelsewer-leakathletic-facilitiesBig-TenWilliams-ArenaHuntington-Bank-Stadium
Added May 2026Updated May 2026Via ingestion