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3. Bioretention/Rain Gardens: Higher priority BMP selected. <br /> 4. Downspout Dispersion: Higher priority BMP selected. <br /> 5. Perforated Stub-Out Connections: Higher priority BMP selected. <br /> Other Hard Surfaces: <br /> 1. Full Dispersion: Not feasible due to not having 65% preserved vegetation. <br /> 2. Permeable Pavement: With a depth to water table/hardpan of 36 inches, permeable <br /> pavement is feasible. The main portion of the driveway to the detached garage <br /> (1,127 sf) that cannot utilize sheet flow dispersion will be turf stone (permeable <br /> pavement). The remainder of the driveway surfaces have the required flow paths <br /> for sheet flow dispersion and shall be concrete and asphalt. <br /> 3. Bioretention/Rain Gardens: Not feasible due to site size limitations. <br /> 4. Sheet Flow Dispersion: Feasible and selected for all impermeable pavement <br /> surfaces. <br /> Runoff from the concrete driveway to the house and concrete pad in front of the <br /> detached garage shall sheet flow to the west and east, respectively. The runoff will <br /> flow through a 2-foot wide transition zone before dispersing through amended soils <br /> with the minimum required flow paths for sheet flow dispersion. <br /> 5. Concentrated Flow Dispersion: Higher priority BMP selected. <br /> 8. RUNOFF TREATMENT <br /> As noted before this project proposes to install a total of 2,348 of PGIS to serve this project <br /> based on the Owner/Applicants plans. <br /> Per the 2014 DOE Stormwater Manual "Minimum Requirements 6: Runoff Treatment — <br /> Requirements" a project is required to provide runoff treatment if: <br /> (a) Projects in which the total effective, pollution-generating impervious surface (PGIS) is <br /> 5,000 square feet or more in a threshold discharge area of the project; or <br /> (b) Projects in which the total of pollution-generating pervious surface (PGPS) is three- <br /> quarters of an acre or more in a threshold discharge area, and from which there is a surface <br /> discharge into a natural or man-made conveyance system from the site. <br /> As shown in the area summary above this project proposes to construct less than 5,000 sf <br /> of PGIS and is therefore below the threshold of requiring runoff treatment. <br /> Fogg-LEXAR SLDS 19-0506 <br /> July 2019 <br /> Revised:September 2019 Page 10 <br />