A landmark power plant in Owatonna, Minn., damaged in a 2010 flood, has new life as the headquarters of Owatonna Public Utilities (OPU) following a renovation by architecture firm LEO A DALY.

When the Straight River flooded in 2010, 12 feet of water stood in the basement of the Owatonna power plant, a gorgeous brick Italianate building instantly recognizable for its neon sign, arched windows and three silver smoke stacks. The flood damage rendered its generators inoperable, but OPU sought LEO A DALY's help in repurposing the building. “OPU realized that the building is so much a part of them and their community,” says Bill Baxley, design director for LEO A DALY. “They wanted to continue its viability by turning it into their headquarters.”

The unique interior volume of the turbine hall — 50 vertical feet of open space that had previously accommodated the plant’s massive boilers — guided LEO A DALY’s approach to space planning for the administrative and customer service spaces that would occupy the building. "We wanted to take advantage of this glorious three-story open interior space — not just to carve it up into cubes, but transform it into a different kind of office space that tells its own story while continuing to serve OPU and the community,” Baxley says.

Because of incomplete documentation of the existing building, the LEO A DALY team started by using laser scanning to create a 3D model of the building’s interior. Then, using the interior steel structure as scaffolding, designers laid out a program of atrium spaces and floating offices that cantilever over the ground floor in inventive ways. The total effect is a series of distinct but connected spaces, all flooded by daylight through the building's monumental windows. “The elevated spaces exist in dialogue with the building's history, especially the exposed steel beams that once supported the boilers,” Baxley says. “Now, instead of producing energy, this space produces the ideas that make the utility function.”

The building also communicates its history by integrating artifacts from its pre-flood days. Boiler doors, valve covers and valve wheels are re-presented in a gallery space. Bar grating is reused in the new building as railings. Energy-efficient windows were installed while preserving the original window framing and some of the original glass in place. Colors, textures and materials from the original floor and equipment are incorporated in a way that recalls the historic structure.

In order to prevent future flood damage, flood doors were installed in a conditioned space below the flood line, which will allow river water to come and go without disrupting operations above. To pull this off, the architects had to raise the first occupiable floor by one foot. 

Baxley sees the Owatonna renovation as part of a growing trend. More cities are interested in repurposing their heritage facilities, rather than simply razing them and building new.

“It’s always great to have a client like the Owatonna Public Utility who recognizes the value that their unique buildings bring to an area.” he says. “This power plant is a great example of preserving something that gives the town character. Thanks to this renovation, this great building will last for another century.”