At Maggie Daley Park, one of the project’s defining challenges was to find a material that could sit above an underground parking garage, which could only support a limited weight. In addition, the park’s design brief called for “a complex landscape that offers experiential range” with varied character, scale, and seasonal attributes. To build any kind of varied topography and support the planned winter “ice ribbon” and play spaces, it was necessary to use a fill material that was lighter than soil. Geofoam, at approximately 1/100 the density of dirt, was the obvious solution.