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Due to underlying soils conditions and infiltration is not recommended on this project <br /> site. <br /> 3. Bioretention in accordance with BMP T7.30 <br /> Bioretention is not feasible due to site constrains, soils conditions and infiltration is <br /> not recommended on this project site <br /> 4. Sheet Flow Dispersion in accordance with BMP T5.12 or Concentrated Flow Dispersion <br /> in accordance BMP T5.11. <br /> BMP T5.12 Sheet flow dispersion Systems is feasible and was selected for this <br /> project driveway flows. <br /> Also flow dispersion will be used for the landings to the maximum extent possible <br /> given site grades <br /> The location and types of BMPs selected are shown in the project site/drainage plans —See <br /> FIGURE 2 EXISTING AND DEVELOPED DRAINAGE & SWPPP PLAN. <br /> MINIMUM REQUIREMENT NO. 6 — Runoff Treatment <br /> The total effective, pollution-generating impervious surface (PGIS) is 3,254 sq. ft <br /> The total of pollution-generating pervious surface (PGPS) is 4,978 sq. ft. <br /> The following require construction of stormwater treatment facilities: <br /> i. Projects in which the total of pollution-generating hard surface (PGHS) is 5,000 square <br /> feet or more in a threshold discharge area of the project, or <br /> ii. Projects in which the total of pollution-generating pervious surfaces (PGPS)— not <br /> including permeable pavements— is 0.75 acres or more in a threshold discharge area, and <br /> from which <br /> there will be a surface discharge in a natural or man-made conveyance system from the <br /> site. <br /> Per the requirements above, no stormwater treatment facilities are required for this project. <br /> MINIMUM REQUIREMENT NO. 7 — Flow Control <br /> The total project area of effective impervious surfaces is 6,779 sq. ft. <br /> The total project area converts native vegetation to lawn or landscape is 0 sq. ft. <br /> The total project area converts native vegetation to pasture is 0 sq. ft. <br /> Through a combination of effective impervious surfaces and converted pervious surfaces <br /> the 100-year flow frequency from a threshold discharge area is estimated to cause an <br /> increase 0.0585 cubic foot per second over the predevelopment condition. <br /> Drainage Report—9227 4t"Ave W Everett,WA 98204 <br /> Nov. 10,2022 Page 16 <br />