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The Effects of Rain Garden Size on Hydrological Performance
STANDER, E., M. BORST, T. O'CONNOR, AND A. ROWE. The Effects of Rain Garden Size on Hydrological Performance. Presented at 2009 Conference & Trade Show, Northeast Chapter, International Erosion Control Association, Hartford, CT, October 27 - 28, 2009.
To inform the public.
Bioretention systems are vegetated depressions designed to accept stormwater runoff from impervious surfaces. Manuals and guidance documents recommend sizing bioretention cells anywhere from 3% to 43% of their associated drainage areas, based on factors including soil type, slope, amount of impervious cover in the drainage area, and distance from runoff source. This wide range in sizing recommendations provides little guidance to designers and urban planners grappling with finding locations for bioretention retrofits where available land is scarce and expensive. Few studies have specifically evaluated hydrologic performance of bioretention cells with regard to their size. Six bioretention cells of three sizes were constructed at the EPA’s Edison Environmental Center to accept stormwater from equal drainage areas. Cells were instrumented with sensors to quantify the magnitude and timing of the wetting front and detect mounding of infiltrating water at several depths, thus allowing for a systematic analysis of hydrologic performance with rain garden size. A bench-scale study was undertaken to guide the selection of engineered media for the field-scale study.