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ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT: STORMWATER SOURCE AREA TREATMENT DEVICE: HYDRO INTERNATIONAL DOWNSTREAM DEFENDER®
Citation:
NSF INTERNATIONAL. ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT: STORMWATER SOURCE AREA TREATMENT DEVICE: HYDRO INTERNATIONAL DOWNSTREAM DEFENDER® . U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-07/121, 2009.
Impact/Purpose:
information
Description:
Verification testing of the Hydro International Downstream Defender® was conducted at the Madison Water Utility in Madison, Wisconsin. The system was designed for a drainage basin estimated at 1.9 acres in size, but during intense storm events, the system received water from an area up to approximately four acres. The Downstream Defender® is a hydrodynamic vortex separator designed to remove settleable solids and associated pollutants from stormwater runoff. The verification challenge included collecting influent and treated effluent samples during 20 qualified storm events. A qualified storm event was defined as a minimum of 0.2 inches of rainfall, where representative sample aliquots are collected throughout the duration of the event and composited into a flow-weighted composite sample. The influent and effluent sampling areas were equipped with automated samplers and flow monitoring devices to collect and monitor the flows entering and exiting the system. The verification testing concluded that the system was capable of removing approximately 27 percent of sediment, as determined by the total suspended solids (TSS) analytical procedure, and 42 percent of sediment, as determined by the suspended sediment concentration (SSC) analytical procedure. The primary difference between these two procedures is that the SSC analytical procedure is more likely to measure larger and heavier sediment particles as compared to the TSS analytical procedure. An evaluation of the organic sediments (measured by the volatile suspended solids (VSS) analytical procedure) indicated that approximately 20 percent of the influent challenge consisted of organic sediments. Organic sediments have a lower specific gravity than inorganic sediments, and tend to pass through hydrodynamic separators more readily than inorganic sediments. Four of the 20 events had peak flows that exceeded the design capacity of the system (3 cfs), resulting in partial bypass of flows. Particle size analysis conducted on stormwater samples showed the runoff entering the Downstream Defender® removed 90% of particles larger than 250µm, but was ineffective at removing particles smaller than 250µm. The system was cleaned before the start of verification testing, and after the completion of the six month verification period. Maintenance consisted of vacuuming sediments from the sediment chamber. Approximately 416 pounds (dry weight) of sediment was removed from the sediment collection chamber during the maintenance event at the end of the testing period.
URLs/Downloads:
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Verification Statement
ETV REPORT: STORMWATER SOURCE AREA TREATMENT DEVICE: HYDRO INTERNATIONAL DOWNSTREAM DEFENDER®