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The Role of Ecologists in Designing Rain Gardens: Enhancing Nitrate removal Performance
Citation:
STANDER, E., M. BORST, T. OCONNOR, AND A. A. Rowe. The Role of Ecologists in Designing Rain Gardens: Enhancing Nitrate removal Performance. Presented at Annual Meeting of the Ecological Society of America, Albuquerque, NM, August 02 - 07, 2009.
Impact/Purpose:
To inform the public.
Description:
Rain gardens are vegetated surface depressions designed to receive stormwater runoff from roads, roofs, and parking lots. Stormwater infiltration through rain gardens’ sandy soils is intended to have both water quantity and quality benefits, through stream peak flow reduction and pollutant transformations. Studies have demonstrated high removal rates of phosphorus and heavy metals through adsorption. Nitrate removal is usually low, causing prominent researchers to call for denitrification research in rain gardens. Terrestrial denitrification experts, often trained as terrestrial biogeochemists or microbial ecologists, are needed to engage in rain garden research and work with stormwater engineers to enhance rain garden design in order to improve ecological function and facilitate monitoring efforts. Rain garden research at the US Environmental Protection Agency’s Urban Watershed Research Facility explores the use of shredded, unprinted newspaper as a media carbon amendment and deep zones of saturation to facilitate denitrification by providing labile carbon and anoxic conditions in pilot-scale, experimental rain garden mesocosms. A bench-scale test was first performed to determine the drainage capability of a locally-available, engineered, sandy media containing shredded newspaper layers. Stormwater was introduced to bins containing zero, one, and two layers of shredded newspaper at varying depths. Tests were performed at low and high rates of stormwater introduction. Effluent volumes and flow rates were compared among newspaper treatments. The media was analyzed for grain size, clay mineralogy, and soil characteristics.
