Preexisting site conditions also played a critical role in the development of a new LPOE in Warroad, which was completed in February 2010. Located along the borders of Minnesota and Manitoba, Canada, the 13-acre site overlaps a natural wetland that tested the design team from Minneapolis-based Julie Snow Architects.
The previous LPOE, built in 1962 to provide workspace for two CBP officers, occasionally flooded on the boggy site. An environmental assessment found a more stable plot of land three-quarters of a mile south of the original LPOE, and six miles north of the town of Warroad, that was on a slightly higher elevation. Still, concerns about potential settlement issues with the building’s foundation remained. "We brought in an additional 4 to 5 feet of soil to stabilize the existing saturated soils, and another 2 feet to elevate the building above the existing waterline," says Matthew Kreilich, AIA, design principal at Julie Snow Architects. The new 45,000-square-foot port, which is aiming for LEED Gold certification, comprises three separate, low-slung volumes arranged in a "T" shape. Two buildings parallel the border’s east-west axis. "The low-slung formal quality of the building allows it to have a presence in this vast landscape," Kreilich says. It also keeps sight lines open and helps control solar heat gain and glare.
Because of the soggy soil conditions, each component is built on 60-foot-deep steel friction piles topped by a structural slab that supports the entire building. The plumbing system is suspended from the bottom of the building and can move independent of the building as the soil shifts. "There’s a lot of money below grade," Kreilich says.
Stormwater is managed with a three-part system. To the north, the team planted native grasses and wetland plantings to slow drainage; to the southwest, a pond with several bays slows filtration; and to the east, two bioswales retain excess water for 72 hours as it filters through plantings before discharging into the wetlands.
When it came to energy, running natural gas to the new site would have been cost-prohibitive and building the new structure to operate on propane, as the previous port did, would have been a security hazard. The solution: a closed-loop geothermal system of 78 wells drilled to a depth of 410 feet. Paired with this is an in-floor radiant heating system in all work areas, and a backup generator and backup boilers that were installed to meet security requirements. In spaces such as the firing range and secondary inspection areas, which are closed spaces, a forced-air system controls temperatures and ventilation. So far, energy costs are calculated to be 39 percent below the firm’s baseline.
The structure is clad in FSC-certified cedar planks, a reference to the area’s history of building with wood. They are treated with a low-VOC stain and a ventilated cavity system increases the cedar’s longevity and reduces moisture and mold buildup. On the exterior, the stain is a dark black, but as travelers move into the inspection areas and public spaces, the stain changes to a warmer heartwood color to create a more welcoming environment and a two-toned wayfinding element for drivers. Scrap wood from the exterior was used for the public spaces’ millwork and furnishings, including the reception desks, benches, and an interior wall.