Laserfiche WebLink
Flow Control <br />Approximately two thirds of the site will be covered by impervious area consisting of <br />building roofs, walkways, and pavement. The increase in runoff from these impervious <br />areas will be mitigated by the installation of a detention tank. As demonstrated by the <br />calculations in Appendix A a theoretical length of 90 LF of 36 inch diameter pipe will <br />provide adequate storage to meet the standards of matching''/z of the 2 year, the 10 year <br />and the 100 year existing runoff rates. Applying the required 35% correction factor yields <br />a required length of 122.4 feet. 120 linear feet of 36" pipe, plus 4 type 2 catch basins will <br />provide this storage volume. <br />Runoff Treatment <br />The project will create approximately 3,300 SF of paved area that will experience <br />vehicular traffic. Since this area is less than the 5,000 square foot threshold identified in <br />Section 1-3.2.1 of the City's Stormwater Management Manual no water quality treatment <br />is proposed. Some reduction in suspended solids will likely be realized by the onsite <br />catchbasins and detention system. <br />Vl. Source Control BMP's <br />The Storniwater Management Manual sets a 4 step process for determining required <br />source control BMP's. <br />,Step l: Select source control BAIP :s based air construction site activities <br />Table 1-4.1 of the Stonnwaler Management Manual gives a checklist for construction site <br />activities that may require source control BMP's. Listed activities expected to occur <br />include the uncovered parking of vehicles; minor application of fertilizers to the new <br />landscape plantings; the potential use of hazardous products such as paints, sealants, and <br />concrete; solid waste generation from construction debris; and the potential for concrete <br />contaminated wash water associated with the delivery of concrete for the proposed <br />building's footings and basement and sidewalks. Applicable BMi"s are listed in Table <br />6.1. Implementation instructions for each BMP arc listed in chapter 4 of the Stormwater <br />Management Manual. <br />Table 6.1: Applicable Construction Source Control BMP's <br />BMP 9 <br />Description <br />C 1.20 <br />Handling of Petroleum Products _ <br />C 1.30 <br />Nutrient Application and Control <br />C 1.40 <br />Solid Waste Handling and Disposal <br />C 1.50 <br />Usc of Chemicals/ Hazardous <br />Products During Construction <br />C 1.70 <br />Spill Control Planning and Cleanup <br />C 1.90 <br />Concrete Trucks/ Spray Washing of <br />Exposed Aceregate Driveways and <br />Walkways <br />Habitat for Humanity- Monagan Mor Page 10 <br />