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7. ON -SITE STORMWATER MANAGEMENT <br />The use of infiltration trenches for the proposed roof and driveway surfaces for this project <br />have shown to comply with the LID Performance Standard. Based on the drainage design <br />in 2010 by Deccio Engineering Inc, infiltration is feasible on this site and soils consist of <br />course sand to sand". (See Appendix A for drainage design letter). Using the WWHM2012 <br />computer model witha standard infiltration rate of 2 inches per hour for sand, a 40-foot long <br />by 4-foot wide infiltration trench for the driveway and a 25-foot long by 5-foot wide infiltration <br />trench for the roof surface showed to infiltrate 100 percent of hard surface runoff. As a result, <br />this project demonstrates compliance with the LID Performance Standard, and is not <br />required to use on -site stormwater management BMPs from List #1. (See Appendix A for <br />WWHM report). <br />8. SUMMARY <br />This project proposes to construct less than 5,000 sf of new hard surfaces. As a result, the <br />use and land cover for less than 5,000 sf of the site will be converted pervious to impervious <br />surfaces. Stormwater management techniques have been incorporated into the design. <br />Therefore, the stormwater design for this project has met or exceeded all of the applicable <br />Minimum Requirements 1-5. <br />271h Dr SE - Haack 19-0508 <br />May 2019 Page 9 <br />