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Depot’s Historic Renovation Took a Fast Track

Interior view of Union Depot station
Skylights were refurbished, plaster was cleaned and repaired, and walls were repainted to bring the Union Depot station in St. Paul, Minnesota, back to life. Greg Ellis

Restoring the Union Depot in St. Paul, Minneapolis—shuttered and neglected since the 1970s—so that it could become a modern multimodal transit center took painstaking effort by architects, engineers, and builders.

January 15, 2013—Minneapolis-based Mortenson Construction is no stranger to big projects, but the restoration of the Union Depot rail facility in St. Paul, Minnesota, presented a daunting challenge. “We were performing pile driving and major demolition at the same time we were doing plaster restoration, painting, enclosure tasks, and making sure the structure was weather tight,” says Kevin Dalager, the project manager for the firm, which served as the design/build contractor for the project. “It wasn’t just, build the foundation and put the structure up, but rather, let’s do everything at the same time and also make sure there’s continued access to the building for the 39 condominium owners.”

Not to mention an extremely tight deadline for a scheduled wedding in the head house, the station’s column-lined neoclassical entrance portico.

On December 8, 2012, more than 20,000 people attended the grand reopening of the Union Depot, a historic neoclassical 1920s-era transportation center on a 33-acre site along the Mississippi River in the Lowertown section of St. Paul. The last passenger train chugged out of the depot in 1971 and, three years later, Union Depot was listed in the National Register of Historic Places. Under the direction of the owner, the Ramsey County Regional Railroad Authority, Mortenson worked with San Francisco-based URS Corporation—which conducted the transportation engineering and designed a new parking structure—and Minneapolis-based HGA Architects, which designed the architectural restoration and also performed the mechanical, electrical, and structural engineering—to ensure that all aspects of the project met the historic preservation guidelines. 

The $243-million restoration of the facility included returning it to its original 1920s color scheme by completely repainting and replastering the 27,000 sq ft waiting room and head house. The project also involved the reconstruction of the carriageway, the long drive to the entrance that dips below ground at one point, into a tunnel. Crews also rebuilt the train deck and tracks and constructed a new multilevel passenger drop-off entrance with ticket and baggage counters. Union Depot is expected to serve as a multimodal Midwest transportation hub, bringing together Amtrak service, local and light-rail transit lines, and bus, motor vehicle, bicycle, and pedestrian traffic. It may also serve as a stop on a future high-speed rail line from Chicago. 

 Exterior view of Union Depot station which features a reconstructed carriageway that leads to the colonnaded head house

Work on the historic structure included reconstructing the
carriageway that leads to the colonnaded head house, which had
to be completed early to accommodate a wedding. Greg Ellis 

Union Depot was fast-tracked due to the availability of federal stimulus money, but other deadlines added to the sense of urgency. Christos Restaurant in the head house had contracted to host a wedding in December 2011, so construction crews had about four months beginning in August of that year to demolish a concrete overlay foundation, restore the original floor of Tennessee pink marble, and refurbish the skylights and a 40 ft plaster ceiling—all while maintaining public access to a pedestrian skyway that connects the building to others in the vicinity. To create access for future light-rail, the old carriageway tunnel had to be demolished and a new one built, providing universal access that included a passenger drop-off area and a new glass elevator.

The grand waiting room is 60 ft wide and 100 yds long with walls rising to a 40 ft high domed ceiling. Three series of skylights had been painted over during World War II in compliance with blackout rules. The plaster and paint were badly degraded and the stone and brick walls were stained and dirty, including a beautiful terra-cotta frieze that wrapped around the stone. “We used a rolling scaffold system to restore the ceiling by thirds,” says Dalager. “We cleaned the stone and frieze.”

There are two portions to the skylights, the laylight—which is the horizontal surface—and the skylight or lantern, which is the vertical surface; these were cleaned separately, the former covered in pigeon guano, Dalager says. “It was the first natural light to hit the floor in 70 years,” he explains. Metal panels that covered the large steel-framed windows were removed, the windows were cleaned, and storm windows added for thermal purposes. “And we replaced over 2,500 tiles in the terrazzo floor,” Dalager adds.

History was uncovered daily during the renovation in the form of notebooks, old shoes, and newspapers. “We even found a bowling alley on the second floor; it was a real surprise to find it on an elevated floor,” Dalager says.

Matching the original paint posed yet another challenge. “The original color was gold, kind of reminiscent of wheat fields,” says Michael Bjornberg, HGA’s project architect. Another challenge was adding sprinkler heads to the plaster ceiling. “We originally thought we could put the sprinkler heads inside the plaster rosettes, but we couldn’t do that without destroying the rosettes,” he explains. Mechanical systems in the interstitial space above the ceiling had to wait for asbestos and pigeon dung removal before laser scanning could be used to determine the optimal placement of the new sprinkler system. HGA also discovered significant deterioration of some of the steel columns supporting the waiting room, so reinforced concrete jackets were used to restrengthen the columns.

URS Corporation renovated the 300,000 sq ft train deck, which exhibited significant deterioration, particularly in the sections closest to the Mississippi River, rolling some 200 ft to the south at its nearest point. “We had to demolish and rebuild 30,000 square feet of the reinforced concrete train deck,” says Greg Brown, P.E., M.ASCE, a project engineer with URS. Another 30,000 sq ft had to be patched and repaired, he says. Timber pilings supporting the 20 in. deck had eroded and some had to be replaced. Additionally, sacrificial anodes were installed in many of the steel columns underneath “to address corrosion issues and cathodic protection,” Brown explains.

The depot originally featured about a dozen stairways and platforms leading from the waiting room down to the tracks. Only one remained and was in an “awkward” spot, according to HGA’s Bjornberg, so, he says, “We picked it up and moved it to a historic display until it may be needed for a future rail connection.”

The wedding was held as scheduled on December 3, 2011. A year later, the restoration of Union Depot was complete and its future as a multimodal transportation hub had begun. One visitor at the grand reopening recalled taking a train out of Union Depot in the 1960s to begin basic training for the army. It was his first time back in the station.

“The pace of the project ... involving so many entities ... to have a schedule this fast seemed almost impossible,” says Bjornberg. “The fact that it moved so well with virtually no hitches was unique to me.”



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