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7. ON-SITE STORMWATER MANAGEMENT <br /> As documented in Section 1 of this report this project is required to meet Minimum <br /> Requirements 1-5. As a result, this project is required to use the On-Site Stormwater <br /> Management BMP's from the 2019 DOE SWMMWW. <br /> Per the DOE SWMMWW the BMP's must be evaluated in the order they are listed. <br /> BMP's for roofs: <br /> 1. Full Dispersion: Not feasible due to the 65:35 requirement. <br /> 2. Downspout Infiltration Systems: <br /> Due to the soil type and roof area of the proposed SFR, the required infiltration BMP <br /> area would not fit on the property. Therefore infiltration is not feasible due to lot size <br /> restriction. <br /> 3. Downspout Dispersion Systems: <br /> Minimum flow paths cannot be achieved; therefore, downspout dispersion is infeasible. <br /> 4. Perforated Stub-out Connections <br /> Feasible and selected. The roof runoff shall be directed to a perforated stubout <br /> connection before connecting to the existing catch basin in the right of way that drains <br /> to the existing CB within Highland Dr SE. <br /> BMP's for other hard surfaces: <br /> 1. Sheet Flow Dispersion: <br /> A total of approximately 718 sf of PGIS is proposed for this project. The runoff <br /> generated..by the.driveway. surfaces will be.dispersed via sheet flow dispersion. Asper <br /> BMP 12.70, a minimum 10 ft flow path over amended or existing vegetated soils, <br /> meeting BMP 12.20 will be provided for the PGIS runoff before the dispersed sheet <br /> flows leave the site, are collected by any critical area or pass over any additional hard <br /> surfaces. <br /> Finally, any area of the site not proposed to be covered with impervious surfaces but <br /> graded or compacted will be treated to meet the criteria for BMP 12.20. Please refer to <br /> the engineering plans for basic soil amendment notes. <br /> 8. SUMMARY <br /> This project proposes to construct less than 5,000 sf of new impervious surfaces including <br /> driveway and roof areas. As a result, the use and land cover for less than 5,000 sf of the <br /> site will be converted from pervious grass to impervious surfaces or replaced impervious <br /> surfaces..:.erasiteatormw.ater:,:management_techniques;have been incorporated into the <br /> design to mitigate for this land conversion. In addition, based on .the proposed <br /> improvements for the site drainage design the post developed runoff from the site is <br /> expected to be slightly greater than the runoff from the existing system. Therefore, the <br /> stormwater design for this project has met or exceeded all of the applicable Minimum <br /> Requirements 1-5. <br /> Kedrich SFR 20-0724 <br /> August 2020 Page 9 <br />