First Environment designed two vegetated bioswales intended to serve and treat stormwater runoff from a select area of impervious surfaces located at the medical center. The selection of bioswales as the most cost-effective “green technology” controls followed a site-wide analysis of storm drainage areas and a review of potential locations for best management practices (BMP) to serve both stormwater runoff and environmentally sensitive areas. Area floodplain implications and ongoing infrastructure projects were also considered during the analysis.
The bioswales were designed consistent with the requirements of Section 438 of the Energy Independence and Security Act (EISA) in accordance with the 95th percentile rainfall event, and Total Suspended Solids (TSS) removal criteria imposed by Delaware’s Department of Natural Resources and Environmental Control (DNREC) Sediment and Stormwater regulations. Additional design inputs included data gathered from site topographical surveys, wetlands delineation, and underground utility surveys additionally performed by First Environment. 25, 50, 75 and 100 percent design drawings were prepared for review by medical center representative and a third-party contractor who will ultimately execute the design.