Practicing ArchitecturePracticing Architecture
Coast Guard Headquarters Is Striking, Surprising, and Sustainable
This new building on Washington, D.C.’s historic St. Elizabeths Hospital campus both repairs and reflects the surrounding landscape.
By Kim A. O'Connell
Everything about the new U.S. Coast Guard Headquarters speaks to the land—quite a paradox for a maritime-focused agency. The massive building, located on the western edge of the historic St. Elizabeths Hospital campus in southeast Washington, D.C., is terraced down the side of a hill, surrounded by hundreds of new trees and plantings, and covered in the second-largest green roof system in the country. But where is the water, the element most integral to the Coast Guard mission?
Although it is not always obvious, water is actually everywhere—in the master plan, in the underground aquifers, in the courtyards and green roofs that filter runoff, and even (abstractly) in the building. It is also present in the Potomac and Anacostia rivers, which come together near the site and form part of its magnificent viewshed. The building's contextual and sustainable approach to both land and water represents a marked departure from the way federal buildings were planned and sited in the past, a trend that resulted in the many monolithic, inwardly focused mid-century Modern structures that line the core of the capital city.
At 1.2 million square feet, the $453 million Coast Guard building, which opened last summer, is just the first phase in the ongoing rehabilitation of St. Elizabeths, formerly a psychiatric hospital, for use by the U.S. Department of Homeland Security and other federal agencies. The entire project is budgeted at $4 billion, making it the largest project in the history of the U.S. General Services Administration (GSA) and the largest construction project in the D.C. metro area since the completion of the Pentagon in 1943. The project team is a collaboration between several federal agencies and private firms, including Perkins+Will and Andropogon Associates, who led the master planning process and bridging design, as well as HOK, HDR, Goody Clancy, WDG, and Clark Construction Group, among others.
Keeping “the green ring”
Opened in 1855 on a promontory overlooking the low-lying federal core of Washington, St. Elizabeths offered patients and staff sweeping views and ample grounds for physical exercise. The main hospital was designed according to the classic Kirkbride plan, with a central volume and staggered wings in an echelon pattern, which was meant to promote therapeutic access to light and air. Given St. Elizabeths' National Historic Landmark status, it was deemed essential that any rehabilitation of the site respect the hospital as the dominant feature of the 176-acre campus, and that the site remain a contributing factor to the topographic “green bowl” around the capital city.
“The concept starts with the idea of keeping the continuity of the green ring around the city, and reinstating it,” says Ralph Johnson, FAIA, principal and design director for Perkins+Will. “It's a very sensitive site from the standpoint of the historic buildings and the sweeping views. So we had to keep the new building very low—lower than the historic buildings.”
This was no easy feat, given the 120-foot change in elevation from the top of the hill to the bottom. Complicating matters further were the discovery of two aquifers running through the hill, which would have been severely impacted by construction. Working with Philadelphia-based landscape architecture firm Andropogon, the design team developed an 11-level facility in which only the top two levels are above grade. The remaining nine levels are built into and extend out of the landscape, cascading down the hill almost as if Frank Lloyd Wright had transposed Fallingwater into a million-square-foot government facility. The building is further divided into a series of wings and volumes that surround eight planted courtyards, which are also connected and step down the hill, one leading to the other. The stepped scheme vaguely recalls the staggered Kirkbride pattern as well.
“We put a lot of thought into how you would use the mass of architecture in what used to be a wooded lot,” says Yaki Miodovnik, principal of Andropogon. “It was not a healthy woodland, but people perceived it as a woodland, and so we came to the solution of developing these courtyards that would reflect the landscape.” (The site was both contaminated from previous development, requiring soil mitigation, and overgrown with weeds and underbrush.) “We realized they needed to be bigger than usual, to allow the light and views to penetrate the building, and to allow these trees and plants to grow,” says Miodovnik.
Inside the building, the various wings have been named after famous U.S. lighthouses to help orient occupants. The wings are tied together with unifying corridors, including a north-south corridor that overlooks the cascading courtyards called “the bridge,” like that of a ship, and another long corridor at the lowest level known as the “keel.” One hallway features hardwood flooring resembling a ship's decking.
Outside, with its 550,000 square feet of vegetated green roofs, the building virtually disappears into the landscape, which was important for preserving views both out from the site and back toward it from other parts of the city. The building is clad in brick, schist stone, glass, and metal, with the masonry primarily kept to the outer edges closest to St. Elizabeths, picking up its red-brick aesthetic. The most glass appears in areas that frame the courtyards, bringing natural light into the building and forging a connection for workers to the outside.
The courtyards and green roof systems serve manifold purposes: First, they are part of the overall stormwater management program, designed to keep as much runoff as possible on site. Stormwater is captured and filtered through the green roof systems, flowing into the next as needed until it reaches a catchment basin at the bottom of the hill, where it is then recycled for on-site irrigation. The design team estimates that this system reduces onsite stormwater runoff by 47 percent. The roofs also lessen the urban heat island effect, extend the life of the roof membrane, and provide wildlife habitats and recreational and meeting space to workers, earning LEED Gold certification.
Each green roof and courtyard is both a literal and abstract expression of five local eco-regions, from the Piedmont uplands down to the coastal plain. There are 200,000 plants, more than 300 native trees, and about 100 varieties of sedum. One courtyard even features a “dry river bed” that mimics the actual bends of the Potomac as it stretches up toward Washington from the Chesapeake Bay.
“Traditionally, a government building [landscape] might have the aesthetics of the English landscape,” says Thomas Amoroso, associate principal and project manager at Andropogon. “These meadows, by contrast, would need once-a-year trimming of the grasses.” But the landscapes at the Coast Guard buildings require little maintenance, a less-mannered and wild expression of the area’s natural flora. “We were a little surprised that the Coast Guard and the GSA were so open and accepting of this scheme. We're trying to change the [established] aesthetics of hundreds of years,” says Amoroso.
“Breaking the mold”
Johnson says the shift began with the GSA's Design Excellence program, which is how Perkins+Will first became connected with the project. “The whole Design Excellence program was about breaking the mold,” he says. “This project is part of that whole movement. There was kind of a freedom that was given to us. There weren't any imposed stylistic constraints. They wanted us to do a very site-specific building. Here, it was really about integrating the building into the landscape.”