250701_42 ERW_Stormwater Report

Line No. Line ID Flow Rate Line Size (Rise x Span) (cfs) (in) Line Type Line Length Invert Elev. Down Invert Elev. Up Line Slope HGL Down HGL Up Minor Loss HGL Junct (ft) (ft) (ft) (%) (ft) (ft) (ft) (ft) Dn Str Line No. 1 P-8 0.00 24 Cir 33.000 615.75 615.90 0.45 616.61 616.78 n/ a 616.78 Outfall 2 P-77 0.00 12 Cir 22.114 615.75 615.90 0.68 616.78 616.78 n/ a 616.78 1 3 P-12 0.00 30 Cir 32.815 613.68 614.01 1.01 616.78 616.78* n/ a 616.78 1 4 P-11 0.00 24 Cir 16.264 614.11 614.27 0.98 616.78 616.78* n/ a 616.78 3 5 P-10 0.00 15 Cir 65.973 614.37 615.03 1.00 616.78 616.79* n/ a 616.80 4 6 P-9 0.00 15 Cir 61.244 615.13 615.74 1.00 616.80 616.80 n/ a 616.80 5 7 P-7 0.00 15 Cir 33.880 616.00 616.15 0.44 617.02 617.17 n/ a 617.38 1 8 P-6 0.00 15 Cir 90.437 616.15 617.05 1.00 617.38 617.91 n/ a 617.91 7 9 P-5 0.00 15 Cir 90.334 617.15 618.05 1.00 617.91 618.88 n/ a 618.88 8 10 P-4 0.00 15 Cir 72.127 618.15 618.91 1.05 618.88 619.71 n/ a 619.71 9 11 P-3 0.00 15 Cir 85.970 619.01 619.87 1.00 619.71 620.62 n/ a 620.62 10 12 P-2 0.00 15 Cir 92.997 619.97 620.90 1.00 620.62 621.56 n/ a 621.56 11 13 P-1 0.00 12 Cir 151.000 620.90 622.10 0.79 621.56 622.70 n/ a 622.70 12 14 P-20 0.00 12 Cir 10.300 613.68 613.68 0.00 614.42 614.52 n/ a 614.72 Outfall 15 P-19 0.00 12 Cir 138.747 613.78 615.17 1.00 614.72 615.79 n/ a 615.79 14 16 P-17 0.00 12 Cir 80.159 615.18 615.97 0.99 615.79 616.50 n/ a 616.50 15 17 P-16 0.00 12 Cir 74.113 616.07 616.81 1.00 616.50 616.96 n/ a 616.96 16 18 P-18 0.00 12 Cir 24.604 615.18 615.44 1.06 615.79 615.81 n/ a 615.81 15 19 P-21 0.00 12 Cir 23.685 613.78 614.02 1.01 614.72 614.35 n/ a 614.35 14 20 P-24 0.00 12 Cir 16.000 617.35 617.50 0.94 617.84 618.07 n/ a 618.07 16 P-15 0.00 24 Cir 50.597 609.00 610.00 1.98 615.50 615.52* n/ a 615.57 Outfall 21 Notes: *Surcharged (HGL above crown). Hydraflow Summary Report 1

Date: 7/1/2025 Project: Project No: ERW 24006174A Calculated By: MN Checked By: JF Conduit Outlet Protection Calculations Scour Hole # S1 Design Parameters: Design Storm Flow for 25 Year, Q . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Vertical Dimension of Outlet Pipe, D o . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Horizontal Dimension of Outlet Pipe, W o . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tailwater Depth, TW 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Scour Hole Depth, y (1/2 D o or D o ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Apron Dimension Calculations: Minimum Bottom Width, W 1 = 2W o . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Minimum Bottom Length, L 1 = 3D o . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Minimum Top Width (max side slope of 3:1) , W 2 . . . . . . . . . . . . . . . . . . . . . . . . Minimum Top Length (max side slope of 3:1) , L 2 . . . . . . . . . . . . . . . . . . . . . . . . Rip Rap Stone Size Calculations: Unit Dicharge, q = Q/D o = · W 1 = 4.00 ft L 1 = 6.00 ft W 2 = 10.00 ft L 2 = 12.00 ft 2.62 cfs per foot Case I: y = 1/2 D o 0.0125 q 1.33 = 1.08 in Therefore, use TW Apron Thickness, TH = 2×d 50 with filter fabric . . . . . . . . . . . . . . . . . . . . . Median Stone, d 50 = · 5.24 cfs 24 in 24 in 0.50 ft 12 in OFF d50 = 4 in TH = 8 in Case II: y = D o 0.0082 q 1.33 = TW Apron Thickness, TH = 2×d 50 with filter fabric . . . . . . . . . . . . . . . . . . . . . . . Median Stone, d 50 = Notes: 1. The side slopes shall be 3:1 or flatter. 2. The bottom grade shall be 0.0% (level). 3. There shall be no overfall at the end of the apron or at the end of the culvert. 4. Fifty (50) percent by weight of the rip-rap mixture shall be smaller than the median size stone designated as d 50. The largest stone size in the mixture shall be 1.5 times the d50 size. The rip-rap shall be reasonably well graded. 5. The thickness of the rip-rap apron may be two (2) times the median stone diameter provided that the apron is constructed on a bedding of four (4) inches of 3/4 inch clean stone on approved filter fabric material. 6. Rip-rap and filter

may be two (2) times the median stone diameter provided that the apron is constructed on a bedding of four (4) inches of 3/4 inch clean stone on approved filter fabric material. 6. Rip-rap and filter fabric shall meet the standards of the governing Soil Conservation District as well as the requirements of the local municipality. 7. Where the scour hole is to be placed within an existing or proposed waterway: a. The scour hole sidewalls should be eliminated to maintain a smooth hydraulic line along the waterway bottom to avoid inviting turbulent flow from a sudden depression in the waterway. b. If the flow in the waterway is greater than the flow from the proposed outlet, the rip-rap used to construct the scour hole should be sized based on the greater flow value according to the standard rip-rap. Footnote: 1. Tailwater depth shall be the 2 year storm if discharging into a detention basin. For areas where tailwater cannot be computed, use TW = 0.2D o . 1

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