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05-01-'06 15:29 FROM-DIMENSIONS, INC. 4258279218 T-103 P003/003 F-202 <br /> The following are the City's current design requirements for use of SMI StormFilters for runoff <br /> treatment: <br /> 1) The StormFilter must be preceded by a pretreatment wetvault/tank containing at least / <br /> 30%of the 6-month,24-hour storm runoff volume from the contributing,developed 3(2 RA,/ <br /> -drainage area;-or by another DOE-approved pre-treatment device. 426 eo 4 <br /> 2) The StonnFilter must treat,at a minimum,the developed peak flow from the <br /> contributing area for the 6-month;24.-4our storm. •PI 15 1*" <br /> 3) The StormFilter cartridges shall be designed with a maximum flow rate or 15 gpm per <br /> -cartridge,if SBUH or a comparable single-event hydrologicg model is used to generate <br /> -tne flows. If the WWIIM is used-tcrgenerate the flows,the design flow per cartridge <br /> shall be 7.5 gpm. High flows shaltbebypassed around the StormFilter vault, but should <br /> generally pass through the pretreatment device. G 64.01-r cto tip <br /> 4) The StormFilter media shall target dissolved pollutants and nutrients,in addition to total <br /> suspend-A solids. As more effeetme.: --media become available in the future,the <br /> StormFilter shall be upgraded,during routine cartridge replacement,to utili these <br /> improved media. <br /> 5) TheatormFilter shall be designed with the minimum head differential between inlet and <br /> outlet-that is recommended by the manufacturer for the specific Model Used. <br /> Dewnsifeam hydraulic calculations will be performed to demonstrate that downStream <br /> conditions will not reduce the hydraulic potential across the filter,to less than that <br /> recommended by the manufacturer,due to ha water effects. <br /> 6) Routine-maintenance of the StormFilter is required. A detailed operatiOn and <br /> mainternmce plan for the system must be prepared for approval by the City. A certificate <br /> oftystem maintenance must be submitted to the City annually. <br /> 7) Mtimtenance and operation of the StormFilter on this site shall be adapted,in the future, <br /> to reflect the current knowledge regarding this emerging technology. <br /> 8) All odlci applicable,and non-conflicting,criteria in the current edition of SMI's Product <br /> Design-Manual shall be followed in the design,construction,and maintenance of the SMI <br /> StonnFitter on this site. <br /> 9) ror Stutilirilters located downstream of detention systems,the SMI mass loading design <br /> procedure,with the following assumptions,shalt be utilized: <br /> removal required=80% <br /> b. Vb=the volume of dead storage plus the 7-day average live storage volume from <br /> the routing of the 6 month,24-hour storm through the detention system(if a 7-day <br /> routing is not available,use Vb=volume of dead storage) <br /> c. Vr=the runoff volume from the mean annual storm(use precipitation volume Of <br /> -0.4B inches) <br /> tr-- Depth of water in basin,H=depth of Vb <br /> e:—Plean annual rainfall=37 inches <br /> f. Percent runoff capture=90% <br /> g. Event Mean Concentration(EMC) 100mg/L <br /> h. -Allowable cartridge flow rate=7.5 gpm <br /> i-. Mass load per cartridge=36 ibs <br /> j. -For checking that Q can meet Effiv„,assume a particle size distribution after <br /> pretreatment=5% sand, 85%silt, 10%clay <br />