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' ' V <br /> 1 <br /> 5.7 Minimum Requirement#7: Flow Control <br /> IDrainage will be controlled by routing runoff from all areas to be developed through a wetpond <br /> sized to conform to current COE requirements including a 44%volume correction factor applied <br /> to the volume. The pond control structure has been sized to release the developed 2-year, 24- <br /> hour storm at 50% of the predeveloped 2-year rate, the developed 10-year, 24-hour storm at the <br /> predeveloped 10-year rate, and the developed 100-year, 24-hour storm at the predeveloped 100- <br /> ' year rate. The detention volume required within the wetpond including the 44%correction <br /> factor is 23,058 cubic feet. Additional StormSHED sizing calculations can be found in <br /> Appendix C. <br /> IThe existing detention pond constructed for the South Storage Yard project has excess storage. <br /> The analysis completed in this report along with an as-built of the existing facility has found that <br /> I the existing facility has sufficient storage to provide detention for the South Storage and Building <br /> Addition projects. <br /> IAs-Built Detention Volume <br /> Elev. Area (ft2) Vol (ft3) <br /> I 562 5,111 0 <br /> 563 6,498 5,110 <br /> 564 7,496 6,498 <br /> I 565 8,523 8,010 <br /> 565.3 8904 2,614 <br /> Total: 23,425 <br /> I <br /> 5.8 Minimum Requirement#8: Wetlands Protection <br /> IThere are two existing wetlands located onsite.No wetland or wetland buffer will be impacted <br /> by the proposed project. See the Critical Area Study that has been prepared for this project for <br /> Iadditional information regarding on-site critical areas. <br /> 5.9 Minimum Requirement#9: Basin/Watershed Planning <br /> I This project is not within a water quality sensitive area and as such,the requirements specified in <br /> the 1997 COE Stormwater Manual have been used to design the proposed stormwater facilities. <br /> In order to ensure that downstream water quality and streanibank stabilization are not <br /> Ijeopardized, onsite treatment and detention are proposed. <br /> 5.10 Minimum Requirement#10: Operation and Maintenance <br /> IA Stormwater Facilities Operation and Maintenance Manual is provided in Appendix E. <br /> ' DAVID EVANS AND ASSOCIATES,INC. <br /> OPERATIONS CENTER ADDITION JUNE,2010 <br /> ' STORMWATER SITE PLAN PAGE 8 <br />