Beneath the brick pavers that will be installed in the plaza area on the south side of Troxel Hall lies an underground pavement support system. Rhonda Martin, landscape architect in facilities planning and management, said this is the first Silva Cells system to be implemented in Iowa.
The underground system comprises a series of stacked frames, filled with loose soil and topped with permeable platform decks constructed of an ultra-strong resin compound. It provides room for tree roots to grow, filtration and absorption of storm water, and prevents soil compaction in paved, urban environments. The Silva Cells are part of the LEED certification process for Troxel Hall.
Martin said 180 Silva Cell frames and decks are being installed, topped by a layer of gravel and permeable brick pavers that filter water into the underground grid. The system provides about 600 cubic feet of planting soil for each of the three trees in the plaza. Without it, the trees would be limited to about 48 cubic feet of soil, compacted by heavy foot traffic and occasional vehicle access. The system is produced by the San Francisco-based DeepRoot company.