Minnehaha Academy unveiled sleek new designs Friday to rebuild and replace the century-old brick buildings damaged in last summer's deadly gas explosion.

The 100,000-square-foot additions won't just revamp the face of the private Minneapolis school. They will nearly double the amount of space, allowing the school to prepare for a growing student population and potentially add middle-school classes.

"It's a wonderful time for us to re-imagine our school," said Minnehaha Academy President Donna Harris. "It's an exciting time."

The new designs come just seven months after the August blast that killed a receptionist and custodian and injured nine people. The natural gas explosion collapsed part of the brick building, the oldest part of the Upper School campus.

Now, Minnehaha Academy leaders want to start anew with three Scandinavian-inspired buildings at the upper campus along the Mississippi River, reopening by fall 2019. A lower and middle school is about a mile south, housing 450 preschool through eighth-grade students.

In preliminary designs revealed Friday to students and faculty, the additions will be connected and have a light fiber-cement paneled exterior with big windows, reflecting the aesthetic of the school's Scandinavian founders. They will also face the river — a stark contrast to the previous red brick buildings built in 1913 and 1922.

"It looks like a campus," Upper School Principal Jason Wenschlag said. "It provides a nice design contrast."

The new design will double the space of the former 55,000-square-foot building, with a library and more open spaces such as nooks by windows for spaces to study or cafe-style tables. The additions will hold 745 middle and high school students — considerably more than the 350 ninth- through 12th-grade students who were there before. That's because school officials hope to increase the student population over time and are exploring moving sixth- through eighth-grade classes from the Lower School campus to be physically near the high school, as some other private schools in the Twin Cities do.

Since the explosion, high school classes have been temporarily relocated to a former college campus in Mendota Heights. Wenschlag said students and staff are still coping with the tragedy and trying to continue the same school traditions in their interim, smaller space.

"What distinguishes Minnehaha is the sense of community," said Judith Hoskens with Minneapolis-based Cuningham Group, the project's architects, adding that the new spaces reflect that with meeting areas for students and staff.

The three new buildings will replace what's now a parking lot and tennis courts at the campus at 3100 W. River Pkwy. In the footprint of the old building, architects plan to create a grassy courtyard and memorial garden to honor receptionist Ruth Berg, 47, and janitor John F. Carlson, 82, who died in the blast.

School officials didn't release a cost for the project Friday, but they said the three buildings could be phased in over time. The school submitted a proposal for the project to the city's planning commission this week, and there will be a public hearing April 9. If approved, construction could start as early as June.

"We'd like to grow," Harris said. "It's a pivotal time in the life of the school."

Investigation continues

Meanwhile, the National Transportation Safety Board is still investigating the explosion, which could take a year or more to complete.

A pending lawsuit, filed by relatives of Berg last fall, blamed the explosion on mistakes by CenterPoint Energy and a contractor, Master Mechanical.

The Minnesota Occupational Safety and Health Administration (OSHA) investigated CenterPoint Energy and has since closed the case, issuing no citations. But in January, the agency issued two citations to Master Mechanical, fining the company $50,000 for violations in construction safety training and education and its use of lockout devices.

Master Mechanical is contesting the violations and plans to try to negotiate a settlement agreement with OSHA. According to state law, any serious violation that causes or contributes to the death of an employee faces a minimum nonnegotiable fine of $25,000.