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TOWARD EFFECTIVE URBAN BMPS FOR STORMWATER TREATMENT: WET PONDS VS. CONSTRUCTED WETLAND-TYPE RETENTION/DETENTION STRUCTURES
Citation:
Nietch**, C., M Borst*, AND M O'Shea*. TOWARD EFFECTIVE URBAN BMPS FOR STORMWATER TREATMENT: WET PONDS VS. CONSTRUCTED WETLAND-TYPE RETENTION/DETENTION STRUCTURES. Presented at Society of Wetlands Scientists Meeting, Chicago, IL, 5/27-6/1/2001.
Description:
A goal of the Urban Watershed Management Branch of USEPA's NRMRL, Edison, NJ is to develop and demonstrate technologies and methods to manage the ecological risks posed by stormwate runoff from highly developed watersheds. This study, in particular, uses extant data and controlled experiments to research the relative effectiveness of structural best management prctices (BMPs) for stormwater treatment by focusing on the dominant mechanisms for stressor reduction in retention/detention-type structures. Based on their popularity and availability of existing data, the study will focus on a constructed wetland-type design compared with a wet pond-type design. Effectiveness is assessed by the relative retention of sediment, nitrogen, and phosphorus during controlled experiments in BMP mesocosms under different physical design scenarios and simulated rain events. The goal is to develop a comprehensive mechanistic model of sediment and nutrient dynamics in small-scale (1-20 acre runoff area) event-based treatment structures. Data from larger-scale treatment wetlands (e.g., Des Plaines River Wetlands Demonstration Project, IL) coupled with macrophyte productivity studies suggest that the presence of wetland vegetaiton can enhance hydraulic efficiency, which increases sedimentation and nutrient retention, but also, may result in episodic nutrient mobilization, the effect of which is species-specific. Mesocosm experiments are designed to correlate hydraulic efficiency with sediment and nutrient dynamics to test the hypothesis that reed-based, vegetated systems would be most effective at stressor reduction in stormwater treatment structures.