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F6°RE LI FILTER,Z,o bs►U N a1z rL2 IA <br /> filterra <br />' Bioretention Systems <br />' Table 1: Filterra®Quick Sizing Table <br /> (Western Washington Region) <br /> • Design Capacity <br /> Available Filterra Box Sizes Contributing Drainage Area (CFS) <br /> (feet) (acres) <br /> 4.17x4.17 up to 0.23 0.061 <br /> 4x6 or 6x4 0.24 to 0.28 0.075 <br /> 4.5x8.5 or 8.5x4.5 0.29 to 0.44 0.075 <br /> 6.33x6.33 0.45 to 0.47 0.084 <br /> 6x8 or 8x6 0.48 to 0.56 0.112 <br /> 5x10.5 or 10.5x5 0.57 to 0.61 0.140 <br />' 6x12 or 12x6 0.62 to 0.84 0.168 <br />' Notes: <br /> 1. Sizing table intended for planning level use.The design engineer must use WWHM3 to calculate the appropriately sized <br /> I facility. <br /> 2. Sizing table meets WA DOE 2005 Stormwater Manual's 91%annual stormwater volume filtered and offline 15 minute <br /> water quality flow rate. <br /> 3. Sizing table based on WWHM3 parking/flat and the SeaTac rain gauge with a precipitation factor of 1.0.Other <br /> precipitation and site conditions can affect Filterra sizing. <br /> 4. Sand Filter(Filterra)parameters: <br /> ' • Filter material depth=1.8 feet(22") <br /> • Effective ponding depth=0.75 feet <br /> ' • Zero slope(s)on the filter box <br /> • Riser height=0.7 inches <br /> • Riser diameter=100 inches <br /> ' Filter Hydraulic Conductivity=50 inches per hour <br /> 5. All boxes are a standard 3.5 feet depth(INV to TC). <br /> ' 6. A standard SDR-35 PVC pipe coupling is cast into the wall for easy connection to discharge drain. <br /> 7. Dimensions shown are internal.Please add 1'to each external(using 6"walls). <br /> 1 <br /> 2/17/08 www.filterra.com <br /> ' 11 <br />