NTSB: School blast site still too unsafe to investigate

Removing debris
Workers use a backhoe to remove debris from the collapsed portion of Minnehaha Academy's upper campus following a gas explosion on Wednesday.
Matt Sepic | MPR News file

The damage triggered by Wednesday's natural gas explosion at Minnehaha Academy remains so extensive that it's not safe for investigators to go to the center of the blast.

The National Transportation Safety Board has requested that excavators be brought in to remove debris, and there's no timetable right now for when it will be safe, NTSB board member Christopher Hart told reporters Friday.

"It's going to be quite an extensive process to remove that safely enough so that we can put people in the basement," Hart said.

NTSB investigators began their work Thursday to figure what happened and why. The explosion killed two staff members at the Minneapolis private school.

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Hart said the workers trying to move the meter were a father and son team working for contractor Master Mechanical. The contractor was working for CenterPoint Energy as part of the utility's efforts to move meters from inside buildings to outside to make meter reading easier, he said.

Moving gas meters is a "very hazardous operation" and the NTSB will be inquiring about CenterPoint's oversight of the contractor, he added.

The father has been interviewed and the NTSB expects to interview the son and others, Hart said. They agency hasn't yet determined whether a gas meter found in a parking lot outside the building that exploded was the new meter or the old one, he said.

The NTSB probe will look at all operational and human factors — including possible fatigue — connected to the meter installation, the explosion and the emergency response, Hart said, noting that's standard NTSB procedure. His team also plans to review police body cam video of officers who responded to the explosion.

Hart said earlier in the week he expected the investigation to take a year but that NTSB investigators would probably be on site for five to seven days. On Friday, he said they may stay beyond a week given the delay in making the blast site safe.