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BMPs for Other Turd Surfaces: <br /> • BMP T5.30: Full Dispersion is not feasible due the lack of 100 ft minimum flow <br /> path. <br /> • BMP T5.15: Permeable Pavement is not feasible due to the shallow depth to water <br /> table. <br /> • BMP TT7.30: Bioretention is not feasible due to the shallow depth to water table. <br /> • BMP T5.12: Sheet Flow Dispersion is feasible. Stormwater runoff from the <br /> proposed driveways and parking area will sheet flow through vegetation and <br /> amended soils. <br /> Minimum Requirement#6: Runoff Treatment <br /> The proposed project will not add more than 5,000 sf of pollution generating hard surface <br /> (PGHS); therefore, stormwater treatment facilities are not required. <br /> Minimum Requirement#7: Flow Control <br /> Flow control shall be provided for the proposed project if any of the following thresholds <br /> are meet: <br /> • 10,000 sf or more of effective impervious surface <br /> o The proposed project does not create more than 10,000 sf of effective <br /> impervious surface. <br /> • 1/4 acres of more of forest converted to lawn or landscape and surface water is <br /> discharged from the site into a conveyance system of receiving water <br /> o The proposed project does not convert forest to lawn. <br /> • 2.5 acres of forest converted to pasture and surface water is discharged from the <br /> site into a conveyance system or receiving water <br /> o The proposed project does not convert forest to pasture. <br /> • A combination of hard surfaces and converted pervious surfaces cause a 0.1 CFS, <br /> one-hour time step, or 0.15 CFS, 15-minute time steps, or greater increase in the <br /> 100-year flow frequency from a threshold discharge area as estimated using <br /> Western Washington Hydrology Model 2012 (WWHM) <br /> o WWHM(15-minute time step) was used to determine the pre-developed <br /> and mitigated discharge volumes from the site under developed <br /> conditions. The proposed project will not increase stormwater runoff, for <br /> the 100 year return period,more than 0.15 CFS. Pre-developed runoff for <br /> the 100 year return period is 0.09 CFS. Mitigated runoff for the 100 year <br /> return period is 0.20 CFS (Refer to Section III, Site Calculations). The <br /> proposed lawn was modelled as pasture in the mitigated scenario in <br /> accordance with Runoff Model Representation from SMMWW Volume <br /> V, BMP T5.13. The proposed roofs were modelled as impervious lateral <br />