Trees, Stormwater and Suspended Pavements: Research and Reality: Extended Abstract

This presentation will provide an overview of integrating large urban trees and their associated soil volumes into storm water management solutions, particularly in the densest urban areas utilizing suspended pavement using load bearing modules. Suspended pavement has been recognized by research as an effective method for healthy urban tree growth. Separate research studies from North Carolina State University and University of Tennessee demonstrate the effectiveness of stormwater volume and water-quality benefits that suspended pavement urban tree/soil systems can provide. These research papers on suspended pavement technologies utilizing load bearing modules have demonstrated that runoff from small events is often completely captured by bioretention practices and often produces no drainage to downstream waters because of soil porosity, exfiltration, and temporary storage, akin to traditional bioretention practices. When drainage-producing events do occur, studies have shown that suspended pavement practices are effectively equivalent to traditional bioretention practices and can achieve significant volume reductions within a similar range of values. In addition to the relative volume equivalency, the two studies show that water quality in suspended pavement systems are also comparable to traditional bioretention. Values for Total Suspended Solids (TSS), nitrogen, phosphorus and heavy metal removal are roughly equivalent, and will be reviewed. Case studies of these systems at various scales (including as examples Uptown Normal Streetscape, CSO14 & 15 in Spokane Washington, and Marriott Headquarters in Bethesda, MD) will be presented as well.