“Complicated green roofs and innovative plaza design is where we thrive,” said Soncrant, relaying that Wolff had 21 such projects un- der construction in 2017 in Chicago alone. Soncrant himself led 15 separate high-rise landscapes last year and believes that providing ef- fective green space for tenants is a must-have amenity in Chicago’s post-recession development. “150 North Riverside is a showstopper, an incredible building with a wonderful investment in city beautifi- cation that repositioned an inaccessible, eye-sore site as a convenient pedestrian thoroughfare, entry plaza, and river walk.” The investment was certainly significant and stretching every dollar to improve pro forma is rarely a waste of time. Goettsch Partners origi- nally planned to employ hollowed slab-on-void construction to build up the site topography, but when value engineering analysis revealed that that much site concrete was cost-prohibitive, a new solution was sought. Wolff Landscape Architecture’s experience with an alternative, lightweight, structural fill was extensive, and Soncrant proposed geo- foam as a workable surface substrate substitute. “EPS geofoam has been a go-to product in our designs for many years,” Soncrant said. “We use it whenever we need a light, strong, durable material to fill voids and make architecturally contoured surfaces.” Bringing the design strategy to Goettsch Partners meant providing ex- amples of previous Chicago-area, decked plazas successfully built with geofoam and introducing the design team to ACH Foam Technologies.
Wolff Landscape Architecture’s previous projects with ACH Foam Technologies have included a lightweight rooftop amenity deck on the eleventh floor of Chicago’s Prudential Plaza and at 222 South River- side Plaza Renovation, also located over railroad tracks and along the Chicago River. Geofoam has also solved technical challenges beneath highways, bridge embankments, levees, and other large civil infra- structure applications where loading requirements are substantially greater than anything required by 150 North Riverside.
Developing a pedestrian-friendly site solution meant responding to elevations as low as the river and as high as the roof of the parking structure, a vertical transition of about 15 feet. Animating the long, horizontal site meant creating a multi-level green space connecting 150 North Riverside and the parking structure immediately to greater Chicago in many different directions. “Building with Foam-Control Geofoam allowed us to create a two-tier park system that addresses vertical movement onsite through a combi- nation of ramps and stairs,” Soncrant said. Since single blocks of geofoam can be large enough to fill sections 8 feet long by 4 feet deep, they make building multi-level terraces, ramps, stairwells, and planter boxes easy. As importantly, working with geofoam enables designers to create a custom contour of substrate material in the exact depth needed below specific planting areas. Since a tree may need a soil depth of several feet, a shrub about 18 inches, and grass just 6 inches, building a geofoam base that accommodates appropriate soil depths decreases the overall dead load on the structure and supports controlled, positive drainage across the site. The task of installing the overall landscape and the Foam-Control Geo- foam blocks was won by Twin Oaks Landscaping, Inc., a Chicago-area firm with a national practice dating back to 1983. Steve Jungermann was the man responsible for overseeing the firm’s efforts. “The project was a challenge simply because of where it’s located,” said Jungermann, regarding the complexity of the surrounding cityscape and the site’s abundant elevation changes. “On something as complicated as this it’s imperative to get expert guidance.” Jungermann detailed the challenges of developing material take-offs that account for the quantities of geofoam required to respond to the site’s many grade changes, soil depth-profiles, and architectural con- tours. Working with ACH Foam Technologies’ product representative, Twin Oaks was able to develop an accurate purchase order and devise
“We only work with materials that we know will perform,” said Harris regarding the geofoam value engineering proposition. “Performance, in this case, means supporting the pounding it will take from heavy pedestrian use in Chicago’s harsh weather; being easier, faster, and less expensive to work with; and, most importantly, feeling confident in the material’s capacity to meet loading requirements.” A multi-level green space connects 150 North Riverside and the parking structure immediately to greater Chicago in many different directions.Working with geofoam enables designers to create a custom contour of substrate material in the exact depth needed below specific planting areas. Photo: ©Tom Rossiter Photography
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august 2018
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