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HomeMy WebLinkAboutSUB202000055 Calculations 2020-11-22SHIMP ENGINEERING, P.C. Design Focused Engineering November 20, 2020 Emily Coat, PE County of Albemarle Department of Community Development 401 McIntire Road, North Wing Regarding: SUB 202000055 Proffit Rd Townhomes North Road Plan —Drainage Calcs Dear Emily, Enclosed is the drainage calculations for Proffit Rd Townhomes North Road Plan. The development property has an area of 7.59 acres and a disturbed area of 5.60 acres. The project is a private redevelopment of a site. The proposed stormwater design meets water quality requirements set forth in 9VAC25-870-65 and water quantity requirements set forth in 9VAC25-870-66-B(3) and 9VAC25-870- 66-C. The storm drains and inlets in this project comply with VDOT regulations. Note: all inlets have an assumed time of concentration. Inlet computations use the rational equation for peak flow calculations. If you have any questions about this calculation packet please do not hesitate to contact me at: keane(a)shimp-engineering.com or by phone at 434-299-9843. Keane Rucker, EIT Shimp Engineering, PC 912 E. High St. Charlottesville, VA 22902 1434.227.5140 1 shimp-engineering.com Contents: Road Drainage Calculations: Post-Dev Inlet Drainage Summary Post-Dev Inlet Drainage Map VDOT LD-204 Inlet Capacity VDOT LD-229 Storm Drain Capacity VDOT LD-268 Ditch Capacity Charlottesville, Virginia22902 912 E. High St. Charlottesville, VA 22902 1434.227.5140 1 shimp-engineering.com Proffit Rd TH North Inlet Drainage Area Summary Impervious C 0.9 Pervious C 0.3 To Inlet Area Impervious Turf C A A7 10,590 7,201 3,389 0.71 0.24 A6 4,125 2,805 1,320 0.71 0.09 A5 19,540 13,287 6,253 0.71 0.45 A4A 15,260 10,377 4,883 0.71 0.35 A4 9,540 6,487 3,053 0.71 0.22 A3 3,755 2,553 1,202 0.71 0.09 A2 7,350 4,998 2,352 0.71 0.17 B7 14,180 9,642 4,538 0.71 0.33 B6 6,815 4,634 2,181 0.71 0.16 65A 19,825 13,481 6,344 0.71 0.46 B5 13,255 9,013 4,242 0.71 0.30 B4 7,830 5,324 2,506 0.71 0.18 63A 17,430 11,852 5,578 0.71 0.40 B3 9,880 6,718 3,162 0.71 0.23 D 7,775 5,287 2,488 0.71 0.18 C2 9,295 6,321 2,974 0.71 0.21 F2 684,100 113,256 570,844 0.40 15.70 G 18,560 9,880 8,680 0.62 0.43 I I I I I I I I 1 I I I I II 11 11 �I 1 I I / l / \�I / II 111 1111\ 111 II 11 11 11 11 I '1 __ \♦♦\� 1\III\\ I 1`I 111 11 1`I 1 '1 1111 '1 1111 \ 111 11 I I 1 \\ \ i -` - / II1 �IMM`"',. ♦\\ `♦ b l 11 11 I II 1 1\ __ _ __ __ - - 7-� - - - - - - - - - - - - - - - - - - - - - - - - \ ♦ ♦ ♦♦ \ ♦` '0 _ _ _ 60 ♦ \ ♦♦♦♦--�-___ - _ 1 1 _ ________ `♦ \�- \\-__d4yyft1iYR4YY6 -- -- Q `-�\\- __-` \ \ - -- �%� O - i i 7775 SIP9295 SF\m _ R a bi 1 ` \/—� TO DITCH 2C �735 - - _ - - TO.B 5005 SF A3: 7 I` ♦a♦ 15260 — --- TO Bad Is ! \ 54i $ LOT `;. LOTpoi LOT ICI I rM ec i LOT k' l �1905 b, a LOT I 14180 SF I l Ir_ I LOT LOT I 0 0 o — / LOT I ;m 0' \ IT 5A �\ \j1 5S TO DITCH �\ 15230 SF �a i -J LOT PROFFIT RD TH ° NORTH POSTDEV INLET DRAINAGE MAP 1 I J 77777 _7 80 0 80 160 240 Scale: 1 "=80' Proffit Rd TH North LD-204 Stormwater Inlet Computations Inlets on Grade Only Sag Inlets Only m a E Z y w y d a 15 y O .@, > Z O m V 0 in jti a r ii m 6 f 6 O 2Z. 'N E Y.. O Z' O fA y X X C7 N L 0 V M d E 'd x 15 r! C C N ffi 1 2 3 4 5 6 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 (it) (ac) (in/hr) (cfs) lots) (cfs) ('T) ('/') (T) (it) (it) (cis) (cis) (it) (0) (it) A7 DI-3C 6 0.24 0.71 0.17 4.0 0.69 0.00 0.69 0.015 0.005 0.020 0.083 0.10 0.5 0.20 5.27 6.5 1.12 0.00 1.12 0.14 0.5 0.27 6.99 A6 DI-3B 8 0.09 0.71 0.07 4.0 0.27 0.00 0.27 0.015 0.025 0.020 0.083 1.53 0.10 100.0% 0.27 0.00 6.5 0.44 0.00 0.44 1.80 0.13 100.0% 0.44 0.00 AS DI-3B 8 0.45 0.71 0.32 4.0 1.27 0.00 1.27 0.015 0.025 0.020 0.083 4.62 0.21 99.49/. 1.26 0.01 6.5 2.06 0.00 2.06 6.28 0.25 89.7 % 1.85 0.21 MA DI-3C 6 0.35 0.71 0.25 4.0 0.99 0.00 0.99 0.015 0.005 0.020 0.083 0.13 0.5 0.25 6.54 6.5 1.61 0.00 1.61 0.18 0.5 0.35 8.41 A4 DI-3B 6 0.22 0.71 0.16 4.0 0.62 0.01 0.63 0.015 0.022 0.020 0.083 2.38 0.17 100.0% 0.63 0.00 6.5 1.01 0.21 1.22 4.49 0.20 90.0% 1.10 0.12 A3 DI-3B 8 0.09 0.71 0.06 4.0 0.24 0.00 0.24 0.015 0.020 0.040 0.083 1.52 0.13 100.0% 0.24 0.00 6.5 0.40 0.12 0.52 2.16 0.17 100.0% 0.52 0.00 A2 DI-3B 8 0.17 0.71 0.12 4.0 0.48 0.00 0.48 0.015 0.020 0.040 0.083 1.97 0.18 100.0% 0.48 0.00 6.5 0.78 0.00 0.78 3.40 0.19 100.0% 0.78 0.00 B7 DI-3C 6 0.33 0.71 0.23 4.0 0.92 0.00 0.92 0.015 0.006 0.020 0.083 0.12 0.5 0.24 6.27 6.5 1.50 0.00 1.50 0.17 0.5 0.34 8.12 B6 DI-3B 6 0.16 0.71 0.11 4.0 0.44 0.00 0.44 0.015 0.020 0.020 0.083 1.90 0.16 100.0% 0.44 0.00 6.5 0.72 0.00 0.72 3.15 0.18 100.0% 0.72 0.00 B5A DI-3B 8 0.46 0.71 0.32 4.0 1.29 0.00 1.29 0.015 0.020 0.333 0.333 5.04 0.22 100.0% 1.29 0.00 w. 2x3 Grate 6.5 2.09 0.00 2.09 6.74 0.26 100.0% 2.09 0.00 B5 DI-3B 8 0.30 0.71 0.22 4.0 0.86 0.00 0.86 0.015 0.020 0.250 0.25 3.71 0.19 100.0% 0.86 0.00 6.5 1.40 0.00 1.40 5.32 0.23 99.49% 1.39 0.01 B4 DI-3C 6 0.18 0.71 0.13 4.0 0.51 0.00 0.51 0.015 0.005 0.167 0.167 0.08 0.5 0.16 4.27 6.5 0.83 0.01 0.84 0.11 0.5 0.22 5.90 B3A DI-3B 8 0.40 0.71 0.28 4.0 1.13 0.00 1.13 0.015 0.060 0.084 0.084 2.84 0.18 100.0% 1.13 0.00 6.5 1.84 0.00 1.84 4.40 0.21 100.0% 1.84 0.00 B3 DI-2B 8 0.23 0.71 0.16 4.0 0.64 0.00 0.64 0.015 0.060 0.001 0.001 1.79 0.16 too."% 0.64 0.00 w. 2x3 Grate 6.5 1.04 0.00 1.04 1 2.58 0.17 100.0% 1.04 0.00 C2 GRATE 2x2 0.21 0.71 0.15 4.0 0.60 0.00 0.60 0.015 0.100 0.100 - 0.10 0.5' 0.20 2.00 6.5 0.98 0.00 0.98 0.14 0.5' 0.29 2.44 ' Curb height represents height of critical adjacent grade. LD-229 Storm Drain Design Computations Proffit Rd TH North From To Catch. I Runoff lincrementl Accum. I Total Total Total Up Down Pipe Invert Pipe Pipe Velocity Flow time Structure Structure Area Coef AC AC TOC Intensity Flow Invert Invert Length Slope Diameter Capacity Increment (ac) (min) (in/hr) (cfs) Elev. Elev. (ft) % (in) (cfs) IWO (min) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 A7 A6 0.24 0.71 0.17 0.17 5.00 6.81 1.17 523.80 522.00 58.51 3.08% 15 12.3 6.3 0.15 A6 A5 0.09 0.71 0.07 0.24 5.15 6.77 1.62 521.80 521.30 27.91 1.79% 15 9.4 5.7 0.08 A5 A4 0.45 0.71 0.32 0.56 5.24 6.74 3.75 520.00 516.20 129.70 2.93% 15 12.1 8.7 0.25 MA A4 0.35 0.71 0.25 0.25 5.00 6.81 1.69 519.00 517.00 34.88 5.73% 15 16.8 8.8 0.07 A4 A3 0.22 0.71 0.16 0.96 5.48 6.67 6.41 516.00 513.20 51.92 5.39% 15 15.7 12.2 0.07 A3 A2 0.09 0.71 0.06 1.02 5.56 6.65 6.79 513.00 511.00 24.00 8.33% 15 20.2 14.8 0.03 A2 Al 0.17 0.71 0.12 1.14 5.58 6.65 7.58 508.00 505.50 19.51 12.81% 15 25.0 17.9 0.02 B7 B6 0.33 0.71 0.23 0.23 5.00 6.81 1.57 522.50 521.70 34.50 2.32% 15 10.7 6.2 0.09 B6 B5 0.16 0.71 0.11 0.34 5.09 6.78 2.31 521.50 514.20 144.97 5.04% 15 15.3 8.9 0.27 65A B5 0.46 0.71 0.32 0.32 5.00 6.81 2.19 515.00 514.20 27.09 2.95% 15 12.0 7.5 0.06 B5 B4 0.30 0.71 0.22 0.88 5.36 6.71 5.89 514.00 513.20 30.77 2.60% 15 11.3 9.3 0.06 B4 B3 0.18 0.71 0.13 1.01 5.42 6.69 6.73 513.00 509.20 127.59 2.98% 15 12.2 10.2 0.21 133A B3 0.40 0.71 0.28 0.28 5.00 6.81 1.93 510.00 509.20 28.00 2.86% 15 10.9 6.7 0.07 B3 B2 0.23 0.71 0.16 1.45 5.63 6.63 9.62 509.00 508.40 29.32 2.05% 18 16.4 9.7 0.05 D B2` 0.18 0.71 0.13 0.13 5.00 6.81 0.86 512.60 508.54 5.00 81.20% 12 34.80 - - B2 61 0.00 0.00 0.00 1.58 5.68 6.62 10.44 508.20 505.00 166.05 1.93% 18 15.8 9.6 0.29 C2 C1 0.21 0.71 0.15 0.15 5.00 6.81 1.03 505.00 504.00 14.30 6.99% 15 18.5 8.1 0.03 F2 F7 15.70 0.40 6.27 6.27 20.00 4.17 26.17 493.10 485.70 257.00 2.88% 36 58.9 8.1 0.53 E3** E2 4.35 496.50 495.00 13.87 10.81% 24 64.5 11.7 0.02 E2** E1 4.35 493.00 489.00 32.00 12.50% 24 69.3 12.3 0.04 G G 0.43 0.62 0.26 0.26 5.00 6.81 1.80 529.40 529.00 13.00 3.08% 12 6.8 7.3 0.03 *Connection from trench drain D to B2 is a manufactured Inserta-tee fitting **10 yr Flow from H droCAD model Proffit Rd TH North LD-347 Hydraulic Grade Line Inlet Number 1 Outlet Water Surface Elev.' 2 Do 3 % 4 Lo 5 S,a% 6 H, 7 Junction Loss Final H 19 Inlet Water Surface Elev. 20 Rim. Elev 21 Vo (8) Ho (9) Qi (10) V, (11) ON, (12) Hi (13) Angle (14) Ho (15) Ht (16) 1.3'Ht (17) 0.51A, (18) A2 509.00 1.25 7.58 19.51 1.173% 0.229 17.9 1.741 6.79 14.8 100.8 1.197 0 0.103 3.041 1.520 1.749 510.75 523.99 A3 514.00 1.25 6.79 24.00 0.943 % 0.226 14.8 1.197 6.41 12.2 78.1 0.809 80 1.525 3.531 4.591 2.295 2.521 516.52 524.02 A4 617.00 1.25 6.41 51.92 0.838 % 0.435 12.2 0.809 1.69 8.8 14.8 0.416 77 0.761 1.986 2.582 1.291 1.726 518.73 526.03 MA 520.00 1.25 1.69 34.88 0.058% 0.020 8.8 0.416 3.75 8.8 32.8 0.416 13 0.214 1.046 1.360 0.680 0.700 520.70 525.90 AS 521.00 1.25 6.74 129.70 0.929'/ 1.204 8.7 0.411 1.62 5.7 9.2 0.177 52 0.257 0.845 1.099 0.549 1.754 522.75 529.35 A6 522.80 1.25 1.62 27.91 0.053% 0.015 5.7 0.177 1.17 6.3 7.4 0.216 45 0.277 0.670 0.871 0.435 0.450 523.25 529.82 A7 524.80 1.25 1 1.17 1 58.51 0.028 % 0.016 6.3 0.216 1.17 0.0 0.0 0.000 0 0.000 0.216 0.280 0.140 0.157 524.96 530.80 B2 509.40 1.50 10.44 166.05 0.841 % 1.397 9.6 0.072 10.44 9.7 100.7 0.506 3 0.072 0.651 0.325 1.722 511.12 516.34 B3 511.12 1.50 9.62 29.32 0.715% 0.210 9.7 1.012 1.93 6.7 12.9 0.244 90 0.488 1.744 2.267 1.134 1.343 512.47 519.74 13A 512.47 1.25 1.93 28.00 0.076°/ 0.021 6.7 0.023 6.73 10.2 68.8 0.568 1 0.054 0.644 0.837 0.419 0.440 512.91 519.80 B4 514.00 1.25 6.73 127.59 0.926% 1.181 10.2 0.057 5.89 10.2 60.2 0.568 2 0.057 0.681 0.886 0.443 1.624 515.62 524.80 BS 515.62 1.25 6.71 30.77 0.919°/ 0.283 9.3 0.107 2.19 7.5 16.3 0.302 7 0.069 0.478 0.621 0.311 0.593 516.22 529.35 B5A 516.22 1.25 2.19 27.09 0.098% 0.027 7.5 0.603 2.31 8.9 20.6 0.430 90 0.859 1.892 2.459 1.230 1.256 517.47 525.95 B6 622.50 1.25 2.31 144.97 0.109°/ 0.159 8.9 0.086 1.57 6.2 9.7 0.209 6 0.042 0.337 0.438 0.219 0.377 522.88 529.50 B7 523.50 1.25 1.57 34.50 0.050% 0.017 6.2 0.018 1.57 0.0 0.0 0.000 0 0.000 0.018 0.023 0.012 0.029 523.53 529.35