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A new Fire Station 21 is being built in Portland to withstand a major earthquake, and serve as a fire and life safety facility along the Willamette River. Construction of such a building on a sloped surface extending over the river comes with challenges, said David Dwyer, project manager for Skanska USA Building – the contractor for the $7.8 million project.

The two-story structure will replace a one-story one on virtually the same footprint, Dwyer said.

“It’s not actually native soil because that area is all fill,” he said. “We’ve had to stabilize all the soil.”

Soil stabilization took about six months, starting in October after the former fire station was demolished, Dwyer said. Deep steel pilings were drilled 80 to 100 feet into bedrock, and soil was filled with grout.

“That’s why all the foundation work has taken so long,” he said. “It’s a challenging way to build. We had to get down there deep enough so that the soil was compacted so it doesn’t liquefy in an earthquake.”

The grout had to be pumped at a well-regulated pressure to accommodate different soils beneath the surface, Dwyer said.

On top of all the subsurface work, Skanska is finishing the concrete footing that will support the steel structure. At least half of the 8,000-square-foot building will be supported by 3-foot-wide, 30-foot-long beams that cantilever over the bank, Dwyer said.

The first floor will be built a couple of feet above the 100-year flood zone level; anything lower will be certified by the Federal Emergency Management Agency as water-resistant, he said.

“The next challenge is building the building at a slope,” Dwyer said. “Obviously, we can’t drop materials or build a scaffolding system west of the work area.”

Crews are designing a work platform that will be cantilevered from underneath the building, allowing them to build while preventing spills, he said.

Building the station required local, state and federal approvals, which were granted faster because the dock had been approved for fire station use in 2001, said Connie Johnson, project manager for the city’s Bureau of Internal Business Services.

“One thing that’s compelling is that this location is so good,” she said. “If we had tried to find another location on the river, it would have taken a year to acquire the property and at least another six months to get all the permitting. It was really a good choice.”

A boathouse already constructed by Oregon Iron Works will house two boats. A third will be added later, Johnson said.

The building is designed to accommodate fire and life safety activities in a confined space, said Aaron Whelton, principal of Whelton Architecture; he collaborated with local architect David P. Suttle on the project.

Site factors included seismic issues, river fluctuations, proximity to Interstate 5 and the Hawthorne Bridge, and the city’s desire to keep the greenway pristine and free of additional buildings, Whelton said.

“It’s a huge responsibility,” he said. “There isn’t going to be a building like this in such a prominent location on the river anywhere.”

Efforts were made to reduce the amount of the building’s footprint on the ground; at least 50 percent of the building will be cantilevered over the bank, Whelton said. The apparatus bay, which will hold an all-terrain vehicle and a small fire engine, will be the only portion of the building that completely touches the ground, he said.

The design also creates a living space in a building that will be visible from six different vantage points, including the Hawthorne Bridge and the river, Whelton said.

“Typically, a fire station has a clear front and back,” he said. “We don’t have that kind of luxury. Every portion is visible from some vantage point.”

Bunk rooms will be as far away from I-5 as possible to reduce noise. An exterior deck will be tucked away so firefighters are not always on display. Four firefighters will live at the station, which will have five rooms, according to the city.

A utility courtyard was developed for the building’s air conditioning equipment, which typically would be placed on the roof, Whelton said. The courtyard, which will house the HVAC equipment, the building’s transformer and trash, will be completed tucked away, he said.

“We did a very good job solving those unique challenges,” he said.

The most prominent feature will be artwork called “The Ripple Wall,” by Seattle artist David Franklin. It will be fabricated in Seattle and assembled in Portland, and include a series of vertical aluminum fins on the west side covering a second-floor catwalk around the building. Each fin will have a different profile, creating a unique rippling effect visible from the bridge and the river, Whelton said.

“I think that’s an amazing opportunity to engage the public with art,” he said.

The public also will be able to engage with the space in a community room, which will have views of the river and be open for the public to reserve, he said.

Project construction is scheduled to wrap up in November.