Filtration - system design information
| Device | Drainage area | Entrance/exit velocity | Drain down/detention time | Dimensions | Materials | Layout Recommendations (physical location, off-line placement) | Soils |
|---|---|---|---|---|---|---|---|
| Pretreatment vegetated filter strip (VFS) | < a few acres, max flow path 75-150 ft depending on perviousness, slope of drainage area <5% [1]; [2] | <1 ft/s, flow should be sheet flow and unconcentrated [1] | Maximum 72 hours [2] | VFS width (parallel to sheet flow) = 25-100 ft depending on vegetation, slope and drainage area soil [3]; [2] | Soil, grass [2] | Residential lawns, parking lots, part of riparian buffer [2] | Hydrologic Soil Groups A-D permitted, table for corresponding slopes [9] |
| Level-Spreader - Vegetative Filter Strip System (LS-VFS) | < a few acres [1] | <=10cfs [4] | Maximum 72 hours [2] | LS width (parallel to sheet flow) = 10-100 ft, VFS width >= 30-50 ft [4] | Concrete, soil, grass [4] | Distance from surface waters: LS and VFS must be outside riparian buffer, LS must be outside stormwater setbacks [4] | VFS max slope = 8% [4] |
| Up-Flo Filter | 0.66 acres impervious drainage area per filter module based on Nashville design storm | 0.056 cfs per filter module (max number of modules 6-54) | Round manhole: 4 ft diameter, 7.5 ft high rectangular vaults: 6 ft x 8 ft x 6.5 ft to 15 ft x 13 ft x 6.5 ft | Roads, carparks, commercial properties, airports, offline and online treatment of existing storm drains | |||
| Storm Clean | Filtration flow rates (nominal/max)= 40/80 gpm, Strainer flow rate >= 100 gpm | Filtration surface area (fabric elements) = 6.4 sq ft, Strainer surface area = 4.8 sq ft | Stainless steel | Can be fit into existing catch basin, curb inlet, drop inlet, or downspout | |||
| Gravel filtration | Same as inlet gravel bags are placed around | Varies by need. For example, one version available comes in 11x48, 11x96, and 19x28 inch bags | Bags are high quality woven polymer material with high UV rating, gravel | In front of or around existing catch basin inlets | |||
| Filtration berm | 1 cfs per 8 linear ft | Berm height = 12-18 inches high with 3:1 side slopes, every 100-300 feet depending on slope | Washed, well-graded gravel/rock ¾ to 3 inches in size with <5% fines | Right-of-ways, traffic areas, construction sites | No restriction | ||
| SiltSoxx R by Filtrexx | Varies by application | Varies by application | Available in 5 to 32 in diameter depending on application, up to 200 ft in length | Filtrexx Media in Filtrexx Mesh | Existing inlets, site perimeters, paved surfaces, compacted soils, exposed slopes | Compacted or susceptible to erosion | |
| Shorex R by Filtrexx | Same as catch basin | 15-40 gpm | 15-gallon storage, fits any existing storm drain | Stainless steel or HDPE, EnviroSoxx filtering media cartridge | Existing inlet |