Laserfiche WebLink
Four Corners Short Plat <br />Stormwater Site Plan <br />The existing site conditions are shown in Figure 2 of the Appendix. WWHM software was used to model <br />the site hydrology and calculate runoff peak rates in accordance with SWMM standards. The existing land <br />use conditions summarized in Table 8.1 were used as the pre -developed site conditions for the WWHM <br />model. Refer to Figure 2 in the Appendix for the pre -developed basin delineations. <br />Table 8.1 - Land Use Cover, Pre -Developed Site Conditions <br />McDonalds Property <br />1.31 <br />0.85 <br />0.16 <br />0.30 <br />791h Place SE ROW <br />0.07 <br />0.00 <br />0.06 <br />0.01 <br />Evergreen Way ROW <br />0.30 <br />0.06 <br />0.13 <br />0.11 <br />Total Site <br />1.68 <br />0.91 <br />0.35 <br />0.42 <br />Input and output parameters for the WWHM model are provided in Appendix G of this report. <br />C. Developed Hydrology <br />The project proposes revisions to the McDonalds parking lot to separate the parking lots of the shopping <br />center and the McDonalds Restaurant parcels. Storm drainage from the existing Shopping Center parcel <br />currently is collected and routed through a culvert to the existing swale. The culvert will be removed during the <br />Four Corners project and will connect directly to the stormwater system within the Evergreen Way right-of- <br />way. The McDonalds parking lot will be disconnected from upstream stormwater flows. Table 8.2 below, <br />shows the developed site conditions for the areas shown in table 8.1 above. Table 8.3 below, shows the <br />difference in areas between existing and developed conditions. Figure 3 shows these drainage basins on the <br />developed site plan. <br />Table 8.2 - Land Use Cover, Developed Conditions <br />Table 8.3 - Land Use Cover, Difference between Existing and <br />McDonalds Property <br />0.00 <br />-0.05 <br />-0.01 <br />0.06 <br />791h Place SE ROW <br />0.00 <br />0.01 <br />-0.01 <br />0.00 <br />Evergreen Way ROW <br />0.00 <br />0.04 <br />0.01 <br />-0.05 <br />Total Site <br />0.00 <br />0.00 <br />-0.01 <br />0.01 <br />The project shopping center parcel will be redeveloped under a separate future permit. The overall <br />impervious area for the proposed short plat will decrease by 0.01 acres. <br />CPH Project No. 0024-18-042 October 23, 2020 <br />CPIH CONSULTANTS Page 16 <br />