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Nestled in the foothills above Salt Lake City, the $102-million Natural History Museum of Utah in the Rio Tinto Center began welcoming visitors in mid-November. The new museum rests on a section of what was once the shoreline of ancient Lake Bonneville. It has already garnered praise from the design and building community as well as those wishing to explore the state's unique people, geology and history.

The NHMU, administered by the University of Utah, sits on a 17-acre site on the upper southeastern edge of campus with sweeping views of the Salt Lake Valley. The 163,000-sq-ft museum is now home to a collection of around 1.2-million artifacts, including items from Utah's Native American tribes, regional flora and fauna specimens and the state's sizable number of dinosaur fossils.

Designed by Todd Schliemann of New York City-based Ennead Architects (formerly Polshek Partnership Architects) in partnership with GSBS Architects of Salt Lake City, the building is composed primarily of exposed concrete with unique copper-alloy cladding. The natural patina of the copper alloy blends with the hillside and gives the building a stratified but fractured appearance, evoking the sandstone deserts and rugged mountains of Utah.

The museum is built in steps up the hillside, with exhibits featuring Utah's geography and the history of its people, animals and plant life on different levels. The exhibit spaces are located on the south end of the building, with laboratory, storage and office space on the north end.

The two wings are connected by bridges over a three-story "canyon" that serves as a central gathering and way-finding element. Floor-to-ceiling windows span the west-facing end of the canyon, providing visitors expansive views west to the Salt Lake Valley with the Great Salt Lake and Oquirrh Mountains, home to the Kennecott copper mine, which produced the ore for the building's cladding.

"Ecstatic is not too strong a word for how we feel about this building," says Museum Director Sarah George, who was part of the collaborative design team. "It is beautiful, but it also functions so well. The building we were in before was designed as a library, and there were so many things we could not do there. Now, to be in a space that is designed for us, is just wonderful."

Rooted in Place

Schliemann says he had never visited Utah before receiving the commission for the museum. So, in 2005 he and George, along with others on the design team, began touring the state, visiting the landscapes and people in order to formulate initial designs. "The goal was the illumination of Utah's identity as the starting point for the development of an architecture in the service of science and discovery," Schliemann said in a written statement. "This investigation yielded an extensive database of impressions, observations, verbal histories and narratives that define Utah."

Salt Lake City-based Big-D Construction was selected as the contractor under a CM/GC contract and brought into design early in the process.

"They (Big-D) became significant contributors to what we were doing," says George. "They helped us look for solutions to things early on."

The construction team broke ground in summer 2009. The senior project manager for Big-D Construction, Leon Nelson, says while final designs for the more complicated exhibit spaces were still being completed, the team began work on the north side of the building.

To stabilize the hillside and allow for site excavation, Big-D first constructed a solider-pile wall with timber lagging. The wall was then sprayed with shotcrete to extend its functional life. To reach the final height of 45 ft, the solider pile was topped with mechanically stabilized earth with tiebacks into the hillside.

"It was one of our first challenges on the job," says Nelson. "It wasn't easy construction-wise, but it was not insurmountable." David Dunn, of Salt Lake City-based structural engineering firm Dunn Associates, said isolating the building from the pressures on the hillside was important in order to create large open spaces inside the museum.

"You have to have the soil forces resolved either through a shear-wall or through the building," Dunn says. "If we hadn't done the solider pile, it would have required more shear-walls through the building space. This way we saved costs and got the spaces inside we were looking for."

The Right Mix

Nelson says another significant challenge for the contractors was finding the right concrete mix, which would become both a structural and a visual feature throughout much of the building.

Schliemann wanted a horizontal layered and textured look for the concrete. To reach LEED goals (designers are aiming to achieve Gold certification), a self-consolidating concrete with a high-fly ash content was utilized. Nelson says the team went through eight mock-ups using different wood forms and concrete mixtures before finding one that worked. Eventually, the team used forms made from Douglas fir, which provided the look designers wanted.

"Doing this board-form concrete is kind of old style, but we needed that texture with the grain of the wood. It leaves impressions like a fossil," says Schliemann. "The wood could also be recycled after several uses. The mix of concrete ended up with this soft gray, which I think looks great. The contractors did a great job and they should be proud."

One of the sections of the building without large expanses of exposed concrete is the canyon, where the walls are mostly drywall and plaster with multiple angles recalling the sandstone canyon walls of southern Utah's red-rock deserts.

Nelson says constructing and finishing the walls required building a suspended work platform (dance floor) that filled the canyon space, allowing carpenters and drywall finishers to create the surfaces.

To help regulate heating and cooling in the canyon space, with its west-facing wall of windows, a radiant heating and cooling system was installed before the final concrete floor was poured.

Nelson says his team was able to draw on experience from construction of the Salt Lake City Main Library, completed in 2003, which also used large amounts of both structural and exposed concrete.

"The library was a significant concrete effort, and we had a lot of the same people working on this job. They were able to use their expertise here," he says.

Nelson adds that the team was particularly proud of the landing they constructed for the glass staircase between the third and fourth floors of the building. Referred to by workers as "the foot," the landing bulges out from the shear-wall at the back of the canyon.

"We made a big gang-form in our shop and then lifted it up on the scaffold, attached it to the wall. We used some geofoam filler to reduce the weight and then placed the concrete," Nelson says.

The final test for concrete workers was the upper floor dedicated to the history and traditions of Utah's Native American tribes. After consultations with tribal members, designers created a circular, drum-like space resting directly on the deck, a form and placement that has traditional and spiritual significance to many of the state's Native Americans.

"Building a curved surface and then building things on that curved surface was a challenge for everyone from the concrete team to the carpenters and the people designing the displays," Nelson says. "It takes real skill to build 'round.'"

Beware of the T-rex

Crews working on the finishing touches and displays in the final days of construction not only had a tight deadline to meet but also had to work around some unique obstacles.

"They had to get the dinosaurs in here so the guys working on the dioramas could do their work—and we were still finishing too," says Nelson. "We had to wrap all the dinosaurs in plastic and then be extremely careful doing our finish work."

In addition to the concrete and recycling work, several other sustainable features included placing semi-permeable asphalt in the 150-space parking lot. Photovoltaic panels are being installed on the roof, and cisterns will collect rainwater for irrigation. A large area of Gamble Oak on the hillside was preserved, and improvements to the Shoreline Trail, which runs in front of the building, were made.

Nelson credits two key issues in keeping the complex project on schedule. The first was Big-D's early creation of a building information model. The 3D document spelled out in detail where and how different areas were to be constructed so exhibit and display designers working away from the building site knew exact dimensions and other details. Secondly, Nelson says the regular monthly team meetings among exhibit designers, carpenters and other specialty trades kept things on schedule.

"Early on, we made a mandate that we would get together at least once a month in the same place on-site to go over things," he says. "Overall, I think the whole cast of characters involved in this ended up having a great time."

Project Team

Owner: Dept. of Facilities Management, State of Utah/University of Utah

Architects: Ennead Architects/GSBS Architects (architect-of-record).

Exhibit design: Ralph Applebaum Associates

Landscape architect: Design Workshop, Salt Lake City

General contractor: Big-D Construction

Engineers: civil: Stantec, structural: Dunn Associates Inc., mechanical: Colvin Engineering, electrical: Spectrum Engineers