Laserfiche WebLink
Stormwater Management Plan <br />Inwood Commercial <br />Carlson Engineering, Inc. Page 2 of 6 <br />Boundary, which limits the amount of new impervious surface to 30% of the square footage of <br />each lot within the boundary. All lot areas outside of the district boundary is limited to 75% of <br />the lot square footage. During the first phase of construction, approximately 6.24 acres will be <br />disturbed. After the initial construction, the site will contain approximately 2.57 acres of <br />impervious surface. When the site is fully built out, the site will contain a maximum allowable <br />impervious surface area of approximately 5.67 acres. This 5.67 acres combines the 8.24 acres from <br />the public streets, trail, sidewalks, and additional impervious from the turn lane construction, <br />and a maximum allowable total lot impervious of approximately 5.67. <br /> <br />Stormwater from the site will be collected in storm sewer and routed to the existing stormwater <br />pond located immediately east of the site, and the existing pond south of the site, behind the <br />existing Kwik Trip. These stormwater ponds were designed to provide water quality treatment <br />and rate control for the site in a fully developed condition. See Figure 3 for a proposed conditions <br />drainage map. <br /> <br />For new outlets into the pond immediately east of the site, a sump catch basin manhole will be <br />used in the most downstream manhole to prevent suspended sediment from being discharged to <br />the pond. When tying into existing storm sewer stubs provided for this site, which will be utilized <br />with the development of Lot 2, Block 2, existing 4-foot sumps were provided on the most <br />downstream storm sewer structure. This prevents suspended solids from being discharged to <br />the pond behind Kwik Trip. No additional stormwater treatment practices are proposed for the <br />site. <br /> <br />1.3 Soil Information <br /> <br />For the entire Inwood Site, in November 2014, Braun Intertec drilled seven soil boings to <br />approximate near surface soils in the western and southern portion of the site. These borings <br />indicated near surface soils consist primarily of the silty sand and course graded sand, with areas <br />of clay. <br /> <br />According to the Natural Resources Conservation Service web soil survey onsite soils fall within <br />the Hydrologic Soil Group (HSG) “B” and “C”. <br /> <br />See Appendix C for soil information. <br />