Resolution 5709 - Laserfiche WebLink

facilities prior to modification, bypassing of facilities during modification, and construction timing criteria as applicable. (SEPA Water Policies) 14. Pollutant source control for the fueling facilities shall be required in accordance with City standards. (SEPA Water Policies) 15. The design and construction of the SMI StormFilters shall meet the following criteria: i. The StormFilter must be preceded by a pretreatment wetvault/tank containing at least 30%of the 6-month, 24-hour storm runoff volume from the contributing, developed drainage area. ii. The StormFilter must treat at least the 6-month, 24-hour storm. iii. The StormFilter cartridges shall be designed with a maximum flow rate of 7.5 gpm per cartridge. Flows exceeding 7.5 gpm shall be bypassed around the system, but should generally pass through the pretreatment wetvault/tank. iv. The StormFilter media shall target dissolved pollutants and nutrients, in addition to total suspended solids. As more effective media become available in the future, the StormFilter shall be upgraded, during routine cartridge replacement, to utilize these improved media. v. The StormFilter shall be designed with a minimum of 2.3 feet of head differential between the inverts of the inlet and outlet of the filter. Downstream hydraulic calculations will be performed to demonstrate that downstream conditions will not reduce the hydraulic potential across the filter due to backwater effects. vi. Routine maintenance of the StormFilter is required. A detailed operation and maintenance plan for the system must be prepared for approval by the City. A certificate of system maintenance must be submitted to the City annually. vii. Maintenance and operation of the StormFilter on this site shall be adopted, in the future, to reflect the current knowledge regarding this emerging technology. viii. All other applicable, and non-conflicting criteria in the current edition of Semi's Product Design Manual shall be followed in the design,construction and maintenance of the SMI StormFilter on this site. ix. For StormFilters located downstream of detention systems,the SMI mass loading design procedure, with the following assumptions, shall be utilized: 1. TSS removal required= 80% 2. Vb=the volume of dead storage plus the 7-day average live storage volume from the routing of the 6 month, 24-hour storm through the detention system(if a 7-day routing is not available, us Vb=volume of dead storage) 3. Vr=the runoff volume from the mean annual storm(use precipitation volume of 0.48 inches) 4. Depth of water in basin, H=depth of Vb 5. Mean annual rainfall =37 inches 6. Percent runoff capture=90% 7. Event Mean Concentration(EMC)= 100mg/L EXHIBIT # Z PAGE.__GF 1(