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HomeMy WebLinkAboutWPO202100038 Calculations 2021-12-06Southwood Redevelopment — Village 2 ALBEMARLE COUNTY, VIRGINIA ROAD PLAN, WPO PLAN, & PRELIMINARY SUBDIVISION PLAT DESIGN CALCULATIONS & NARRATIVE JULY 89 2021 REVISED DECEMBER 3, 2021 .•'0*'0 TIMMONS GROUP YOUR VISION ACHIEVED THROUGH OURS. Prepared by: Clint Shifflett, PE Timmons Group 608 Preston Avenue, Suite 200 Charlottesville, VA 22903 434.327.1690 CLINT W. S F LET Lit. N . 54330 12/3/2021 ..a Table of Contents Section Title 1. Project Narrative 2. LD-204 Inlet Calculations 3. LD-229 Pipe Calculations 4. LD-347 Hydraulic Grade Line Analysis 5. Virginia Runoff Reduction Method Worksheet Summary 6. Wet Pond Routing Calculations Project Narrative: This project includes the construction of two roads, a residential community, and associated utilities and landscaping. The limits of disturbance is 4.88 acres. Water Ouality: The current site is undeveloped. 4.88 acres was analyzed for water quality. The total TP load reduction required is 4.60 lbs/year. There will be 3.12 lbs/year to be treated via wet pond SWM A. The remaining 1.48 lbs/yr of required nutrient credits area shall be purchased from a DEQ-Approved Nutrient Credit Bank in Accordance with VA code 62.1-44.15:35. For the overall Southwood Redevelopment project, this brings the total phosphorous reduction provided on -site to 22.30 lbs/yr, and off -site nutrient credits to 4.10 lbs/yr. 79.50% of the treatment is being achieved onsite. Water Ouantity The proposed stormwater conveyance system outfall enters a floodplain and discharges runoff into an established channel with less than 1 % of the contributing drainage area, in accordance with 9VAC25-870-66 section C.3. Wetpond SWM A has been analyzed to ensure adequate storage and routing. No further stormwater quantity measures have been provided as part of this development. Energy balance requirements will be met through the use of one wet pond. Flood protection requirements for the 10-year storm will be met by releasing the stormwater into the mapped floodplain, in accordance with 9VAC25-670-66, Section C.3.c. FORM LD 204 STORMWATER INLET COMPUTATIONS SHEET 1 OF 3 ROUTE PROJECT SouthwoodVillage2 DESIGNER: CHG CHECKED: DATE 12/1/2021 UNITS ENGLISH INLET F aa wS 6 a a.J ¢ 6 w ie � ti Z ip ri UU o ri � V K �° & U� u� tj c¢y i a' i �? E- V C 3 [k V � ¢ � m 3 SS �u o h a V" Z u 'ZLL a 6' V U i E' Sag Inlets Only Z � z d m A 104 D1-211 10 0.120 0.73 00876 0.000'RIGHT 0.088 4 0.352 0 0.352 0.0390 0.0208 1.515 2.000 1.3201 0.0833 4.0048 1.000 3.50 0.1458 0.1666 5.325 6.000 1.878 1.000 0.352 0.000 1.514 106 DI-3B 6.000 0.080 0.69 0.0552 O'RIGH7 0.055 4 0.22 0.047 0.267 0.0450 0.0208 1.330 2.000 1.5038 0.0833 4.0048 1.000 3.50 0.1458 0.1666 4.949 6.000 1.212 1.000 0.267 0.000 1.329 108 DI-2B 10 0.180 0.73 0.1314 O'RIGH7 0.131 4 0.524 0 0.524 0.0430 0.0208 1.726 2.000 1.1587 0.0833 4.0048 1.000 3.50 0.1458 0.1666 6.480 6.000 1.543 1.000 0.524 0.000 1.725 I10 DI-3B 6.000 0.200 0.81 0.162 O'RIGHT 0.162 4 0.648 0 0.648 0.0450 0.0208 1.853 2.000 1.0793 0.0833 4.0048 1.000 3.50 0.1458 0.1666 7.182 6.000 0.835 0.961 0.623 0.025 1.853 112 DI-2B 10 0.230 0.67 0.1541 O'RIGHT 0.154 4 0.616 0 0.616 0.0350 0.0208 1.906 2.000 L0493 0.0833 4.0048 L000 3.50 0.1458 0.1666 6.521 6.000 L534 1.000 0.616 0.000 1.905 114 DI-3B 6.000 0.070 0.72 0.0504 O'RIGHT 0.05 4 0.2 0 0.200 0.0477 0.0208 1.180 2.000 1.6949 0.0833 4.0048 1.000 3.50 0.1458 0.1666 4.461 6.000 1.345 1.000 0.200 0.000 1.180 116 DI-1 2.000 0.260 0.40 0.104 Bwk/Lt. 0.000'RIGHT 0.104 4 0.416 0 Bwk/Lt. 0 4 0 0 Ahead/Rt. 0.416 0.001 2.000 2 0.416 1.388 T>4.0R 118 DI-1 1.500 0.270 0.55 0.1485 0.000'RIGHT 0.149 4 0.596 0 0.596 0.0314 L500 L500 1.000 0.596 0.000 0.121 BHt.=O. 102' 122 DI-3C 6.000 0.100 0.56 0.056 Bwk/Lt. 0.000'RIGHT 0.056 4 0.224 0.006 0.0050 0.0208 L897 2.000 L0543 0.0833 4.0048 3.50 Bnk/Lt. 0 4 0 0 Ahead/Rt. 0.230 0.0050 6 0.230 0.571 0.166 0.333 0.4985 2.571 2.290 Weir Flow 124 DI-2B 10 0.170 0.73 0.1241 O'RIGH7 0.124 4 0.496 0.041 0.537 0.0270 0.0208 1.901 2.000 1.0521 0.0833 4.0048 1.000 3.50 0.1458 0.1666 5.694 6.000 1.756 1.000 0.537 0.000 1.900 126 DI-2B 10 0.340 0.69 0.2346 O'RIGH7 0.235 4 0.94 0 0.940 0.0270 0.0208 3.322 2.000 0.602 0.0833 4.0048 0.979 3.50 0.1458 0.1635 7.286 6.000 1.372 1.000 0.940 0.000 2.329 128 DI-3B 6.000 0.180 1 0.81 1 0.1458 INLETSOFT BY ENSOFTEC DATE: 12/3/2021 FORM LD 204 STORMWATER INLET COMPUTATIONS SHEET 2 OF 3 ROUTE PROJECT SouthwoodVillage2 DESIGNER: CHG CHECKED: DATE 12/1/2021 UNITS ENGLISH INLET OS �,,, aa U ¢`� V ¢ U z k. V V a �" U uUU� x, U O K Uf✓ �y V fi R ¢ o 0c7 z a a x u zLL a. � V U E. Sag Inlets Only W Z W a v z o�� nC O'RIGHT 0. 146 4 0.584 0 0.584 0.0409 0.0208 1815 2000 11019 0.0833 4.0048 L000 3.50 0.1458 0.1666 6.681 6.000 0.898 0.984 0.574 0.010 1814 132 DI-3B 6.000 0.070 0.73 0.0511 O'RIGHT 0.051 4 0.204 0 0.204 0.0350 0.0208 1.260 2.000 1.5873 0.0833 4.0048 1.000 3.50 0.1458 0.1666 4.099 6.000 1.464 1.000 0.204 0.000 1.260 134 DI-3B 6.000 0.050 0.84 0.042 O'RIGHT 0.042 4 0.168 0 0.168 0.0270 0.0208 1.230 2.000 1.626 0.0833 14.0048 1 1.000 3.50 0.1458 0.1666 3.495 6.000 1.717 1.000 0.168 0.000 1.230 136 DI-2B 10 0.090 0.75 0.0675 O'RIGHT 0.068 4 0.272 0 0.272 0.0270 0.0208 1.473 2.000 1.3578 0.0833 4.0048 1.000 3.50 0.1458 0.1666 4.279 6.000 2.337 1.000 0.272 0.000 1.473 138 DI-2B 10 0.250 0.81 0.2025 0.000'RIGHT 0.203 4 0.812 0.01 0.822 0.0100 0.0208 4.494 2.000 0.445 0.0833 4.0048 0.919 3.50 0.1458 0.1548 5.282 6.000 1.893 1.000 0.822 0.000 2.622 140 DI-3A 6.000 0.460 0.72 0.3312 Bwk/Lt. 0.000'RIGHT 0.331 4 1.324 0 0.001 0.0208 10.836 2.000 0.1846 0.0833 4.0048 3.50 Bwk/Lt. 0 4 0 0 Ahead/Rt. 1.324 0.001 6 1.324 1.837 0.166 0.333 0.4985 3.837 7.358 T> 8.0 R 202 DI-1 1.000 0.030 0.70 0.021 O'RIGHT 0.021 4 0.084 0 0.084 0.0600 0.0600 0.817 2.000 2.448 0.0833 1.3883 1.000 2.56 0.1066 0.1666 3.320 1.000 0.301 1.000 0.084 0.000 0.817 204 DI-1 1.000 0.030 0.44 0.0132 O'RIGHT 0.013 4 0.052 0 0.052 0.0500 0.0500 0.706 2.000 2.8329 0.0833 1.666 1.000 2.80 0.1166 0.1666 2.570 1.000 0.389 1.000 0.052 0.000 0.706 206 DI-1 1.000 0.030 0.44 0.0132 O'RIGHT 0.013 4 0.052 0 0.052 0.0500 0.0500 0.706 2.000 2.8329 0.0833 1.666 1.000 2.80 0.1166 0.1666 2.570 1.000 0.389 1.000 0.052 0.000 0.706 208 DI-1 1.000 0.040 0.41 0.0164 O'RIGHT 0.016 4 0.064 0 0.064 0.0500 0.0500 0.764 2.000 2.6178 0.0833 1.666 1.000 2.80 0.1166 0.1666 2.804 1.000 0.357 1.000 0.064 0.000 0.763 210 DI-1 1.000 0.050 0.42 0.021 Bwk/Lt. 0.000'RIGHT 0.021 4 0.084 0 Bwk/Lt. 0 4 0 0 Ahead/Rt. 0.084 0.001 I.000 1 0.084 0.819 T > 8.0 R 212 DI-1 1.000 0.080 0.44 0.0352 O'RIGHT 0.035 4 0.14 0 0.140 0.0300 1000 L000 1.000 0.140 0.000 0.1315 BHt.�.051' INLETSOFT BY ENSOFTEC DATE: 12/3/2021 FORM LD 204 STORMWATER INLET COMPUTATIONS SHEET 3 OF 3 ROUTE PROJECT SouthwoodVillage2 DESIGNER: CHG CHECKED: DATE 12/1/2021 UNITS ENGLISH INLET aa wS e ¢ 6 - ti a ipo x K Ci a' i C [k v%i ¢' oU g zLL �6 s� Sag Inlets Only z oa SG a 214 DI-1 1.000 0.080 0.47 0.0376 0.000'RIGHT 0.038 4 0.152 0 0.152 0.0200 0.0300 1.253 2.000 1.5962 0.0833 2.7767 1.000 3.28 0.1366 0.1666 3.063 1.000 0.326 1.000 0.152 0.000 1.253 216 DI-1 1.000 0.040 0.58 0.0232 O'RIGHT 0.023 4 0.092 0 0.092 0.0127 0.0550 1.131 2.000 1.7683 0.0833 1.5145 1.000 2.68 0.1116 0.1666 2.165 1.000 0.462 1.000 0.092 0.000 1.130 INLETSOFT BY ENSOFTEC DATE: 12/3/2021 47039-STRM 100 STORM SEWER DESIGN COMPUTATIONS STORM FREQUENCY 10 PROJECT: LOCATION: COUNTY: Southwood Village 2 Albemarle Designed by: CHG Checked by: UNITS ENGLISH PIPE NO FROM POINT TO POINT DRAIN. AREA "A" AcreMinutes (3) RUNOFF COEFF. "C" (4) CA TOTAL INLET TIME (7) RAIN FALL In/Hr (8) RUNOFF Q CFS (9) INVERT ELEVATIONS LENGTH of Pipe Ft. (12) SLOPE Ft./Ft. (13) SIZE (Dia. Or Span/Rise) In. (14) SHAPE Capacity CFS (15) Friction Slope Ft./Ft. VEL Vn Ft/Sec (16) FLOW TIME Min. (17) REMARKS (18) 7ALAC ADDTL CA UPPER END (10) LOWER END (11) REFERENCE (1) STA. REFERENCE (2) STA. 129 128 126 0.180 0.810 0.146 0.146 0.000 6.000 6.230 0.908 419.778 419.160 30.899 0.020 15.000 Circular 9.894 0.000 5.039 0.102 127 126 124 0.340 0.690 0.235 0.380 0.000 6.102 6.200 2.359 419.061 416.360 180.089 0.015 15.000 Circular 8.568 0.001 5.974 0.502 123 124 122 0.170 0.730 0.124 0.505 0.000 6.605 6.058 3.056 416.156 415.816 34.007 0.010 15.000 Circular 6.996 0.002 5.521 0.103 121 122 114 0.100 0.560 0.056 0.561 0.000 6.707 6.029 3.379 415.620 414.491 56.457 0.020 15.000 Circular 9.894 0.002 7.316 0.129 117 118 116 0.270 0.550 0.149 0.149 0.000 0.000 8.901 1.322 420.187 417.640 101.893 0.025 15.000 Circular 11.062 0.000 6.084 0.279 115 116 114 0.260 0.400 0.104 0.253 0.000 0.279 8.716 2.201 417.437 416.850 58.717 0.010 15.000 Circular 6.996 0.001 5.059 0.193 113 114 112 0.070 0.720 0.050 0.863 0.000 6.836 5.995 5.176 411.743 411.141 30.110 0.020 18.000 Circular 16.090 0.002 8.129 0.062 137 138 136 0.250 0.810 0.203 0.203 0.000 6.000 6.230 1.262 415.989 414.220 70.779 0.025 15.000 Circular 11.062 0.000 6.002 0.197 135 136 134 0.090 0.760 0.068 0.271 0.000 6.197 6.173 1.672 411.046 410.450 29.806 0.020 15.000 Circular 9.894 0.001 6.013 0.083 139 140 134 0.460 0.720 0.331 0.331 0.000 0.000 8.901 2.948 409.486 408.620 86.601 0.010 18.000 Circular 11.377 0.001 5.417 0.266 133 134 132 0.050 0.840 0.042 0.644 0.000 6.279 6.149 3.961 408.420 408.086 33.373 0.010 18.000 Circular 11.377 0.001 5.872 0.095 131 132 112 0.070 0.730 0.051 0.695 0.000 6.374 6.122 4.256 407.886 407.253 63.360 0.010 18.000 Circular 11.377 0.001 5.986 0.176 111 112 102 0.230 0.670 0.154 1.713 0.000 6.898 5.978 10.238 407.050 406.628 42.038 0.010 18.000 Circular 11.397 0.008 7.315 0.096 109 110 108 0.200 0.810 0.162 0.162 0.000 6.000 6.230 1.009 425.359 423.990 30.431 0.045 15.000 Circular 14.841 0.000 6.919 0.073 107 108 104 0.180 0.730 0.131 0.293 0.000 6.073 6.209 1.822 423.791 422.100 84.547 0.020 15.000 Circular 9.894 0.001 6.162 0.229 105 106 104 0.080 0.690 0.055 0.055 0.000 6.000 6.230 0.344 421.657 421.359 29.827 0.010 15.000 Circular 6.996 0.000 2.962 0.168 103 104 102 0.120 0.730 0.088 0.436 0.000 6.302 6.143 2.679 421.148 419.189 97.933 0.020 15.000 Circular 9.894 0.001 6.867 0.238 IOTA 102 100A 0.000 0.000 0.000 2.149 0.000 6.993 5.952 12.791 406.448 404.910 76.896 0.020 24.000 Circular 34.655 0.003 10.219 0.125 101 100A 100 0.000 0.000 0.000 2.149 0.000 7.119 5.919 12.720 404.707 404.283 42.390 0.010 24.000 Circular 24.505 0.003 7.890 0.090 47039-STRM 200 STORM SEWER DESIGN COMPUTATIONS STORM FREQUENCY 10 PROJECT LOCATION: COUNTY: Southwood Village 2 Albemarle Designed by: CHG Checked by: UNITS ENGLISH PIPE NO FROM POINT TO POINT DRAIN. AREA "A" AcreMinutes (3) RUNOFF COEFF. "C" (4) CA TOTAL INLET TIME (7) RAIN FALL In/Hr (8) RUNOFF Q CFS (9) INVERT ELEVATIONS LENGTH of Pipe Ft. (12) SLOPE Ft./Ft. (13) SIZE (Dia. Or Span/Rise) In. (14) SHAPE Capacity CFS (15) Friction Slope Ft./Ft. VEL Vn Ft/Sec (16) FLOW TIME Min. (17) REMARKS (18) TEREACC ADDTL CA UPPER END (10) LOWER END (11) REFERENCE (1) STA. REFERENCE (2) STA. 215 216 214 0.040 0.580 0.023 0.023 0.000 5.000 6.542 0.152 410.858 408.550 92.311 0.025 12.000 Circular 7.321 0.000 3.739 0.411 213 214 212 0.080 0.470 0.038 0.061 0.000 5.411 6.409 0.390 408.353 407.788 56.429 0.010 12.000 1 Circular 4.630 0.000 3.592 0.262 211 212 210 0.080 0.440 0.035 0.096 0.000 5.673 6.328 0.608 407.788 407.145 64.324 0.010 12.000 Circular 4.630 0.000 4.088 0.262 209 210 208 0.050 0.420 0.021 0.117 0.000 5.936 6.249 0.731 407.145 406.792 35.324 0.010 12.000 Circular 4.630 0.000 4.312 0.137 207 208 206 0.040 0.410 0.016 0.133 0.000 6.072 6.209 0.828 406.792 406.347 44.479 0.010 12.000 Circular 4.630 0.000 4.469 0.166 205 206 204 0.030 0.440 0.013 0.147 0.000 6.238 6.161 0.903 406.347 405.799 54.828 0.010 12.000 Circular 4.630 0.000 4.580 0.200 203 204 202 0.030 0.440 0.013 0.160 0.000 6.437 6.104 0.975 405.799 404.855 94.387 0.010 12.000 Circular 4.630 0.000 4.681 0.336 201 202 200 0.030 0.700 0.021 0.181 0.000 6.773 6.011 1.087 404.855 404.253 60.150 0.010 12.000 Circular 4.630 0.001 4.826 0.208 47039-STRM 100 PROJECT: Southwood Village 2 DESIGNED BY: CHG HYDRAULIC GRADE LINE ANALYSIS I[MIQ:I [M4U:101:7a1:M41VA 10 Year Checked: INLET OR JUNCTION INLET STATION OUTLET WATER SURFACE ELEV. DIA. PIPE Do (In) DESIGN DISCH. Qo (CFS) LENGTH PIPE Lo (Ft) FRICTION SLOPE, Sfo (FT/FT) FRICTION LOSS Hf (Ft) JUNCTION LOSS FINAL H (Ft) Inlet Water Surface Elevation Rim Elev Comments VolHo (Ft) Qi Vi QiVi Vi`2/2g Hi Angle HA Ht 1.3 Ht 0.5 Ht 100A 407.55 24 12.72 42.39 0.27% 0.11 7.89 0.24 12.79 10.22 130.71 1.62 0.57 26.8 0.49 1.3 0 TRUE 0.76 408.31 424.44 OK -16.13 102 408.31 24 12.79 76.9 0.27% 0.21 10.22 0.41 10.24 7.32 74.9 0.83 0.29 76.68 0.55 1.24 0 TRUE 0.83 409.14 424.24 OK -15.1 112 1 409.14 18 1 10.24 42.04 1 0.81% 1 0.34 7.32 0.21 5.18 8.13 42.07 1.03 0.36 80.61 0.68 1.24 0 TRUE 0.96 1 410.11 422.68 1 OK -12.57 114 412.34 18 5.18 30.11 0.21% 0.06 8.13 0.26 3.38 7.32 24.72 0.83 0.29 93.84 0.58 1.13 0 TRUE 0.63 412.97 422.87 OK -9.9 122 415.49 15 3.38 56.46 0.23% 0.13 7.32 0.21 3.06 5.52 16.87 0.47 0.17 61.44 0.27 0.64 0 TRUE 0.45 415.94 420.55 OK -4.6 124 416.82 15 3.06 34.01 0.19% 0.06 5.52 0.12 2.36 5.97 14.09 0.55 0.19 43.54 0.24 0.55 0.72 FALSE 0.78 417.6 420.87 OK -3.27 126 417.6 15 2.36 180.09 0.11% 0.2 5.97 0.14 0.91 5.04 4.58 0.39 0.14 74.61 0.24 0.52 0.67 TRUE 0.54 418.14 426.63 OK -8.49 128 420.16 15 0.91 30.9 0.02% 0.01 5.04 0.1 0 0 0 0 0 0 0 0.1 0.13 TRUE 0.07 420.23 427.06 OK -6.83 104 420.19 15 2.68 97.93 0.15% 0.14 6.87 0.18 1.82 6.16 11.22 0.59 0.21 20.24 0.15 0.54 0.7 TRUE 0.49 420.68 427.74 OK -7.06 108 423.1 15 1.82 84.55 0.07% 0.06 6.16 0.15 1.01 6.92 6.98 0.74 0.26 78.77 0.49 0.9 1.17 TRUE 0.64 423.74 431.14 OK -7.4 110 424.99 15 1.01 30.43 0.02% 0.01 6.92 0.19 0 0 0 0 0 0 0 0.19 0.24 TRUE 0.13 425.12 431.44 OK -6.33 106 1 1 422.36 1 15 1 0.34 1 29.83 1 0.00% 1 0 1 2.96 1 0.03 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0.03 1 0.04 1 TRUE 1 0.02 1422.38 1 427.77 OK -5.39 132 410.11 18 4.26 63.36 0.14% 0.09 5.99 0.14 3.96 5.87 23.26 0.54 0.19 25.14 0.16 0.49 0 TRUE 0.33 410.44 420.41 OK -9.97 134 410.44 18 3.96 33.37 0.12% 0.04 5.87 0.13 2.95 5.42 15.97 0.46 0.16 41.98 0.24 0.53 0 TRUE 0.31 410.75 419.14 OK -8.39 136 411.45 15 1.67 1 29.81 0.06% 0.02 6.01 0.14 1.26 1 6 7.57 0.56 0.2 1 90 0.39 0.73 0.95 TRUE 1 0.49 411.94 418.72 OK -6.78 138 415.22 15 1.26 70.78 0.03% 0.02 6 0.14 0 0 0 0 0 0 0 0.14 0.18 TRUE 0.11 415.33 420.64 OK -5.31 140 1 1 410.75 1 18 1 2.95 1 86.6 1 0.07% 1 0.06 1 5.42 1 0.11 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0.11 1 0.15 1 TRUE 1 0.13 1 410.88 1 416.3 OK -5.42 116 417.85 1 15 1 2.2 1 58.72 1 0.10% 1 0.06 1 5.06 1 0.1 1 1.32 1 6.08 1 8.04 1 0.57 1 0.2 1 26.58 1 0.17 1 0.47 1 0.61 1 TRUE 1 0.37 1418.22 1 421.87 OK -3.65 118 418.64 1 15 1 1.32 1101.891 0.04% 1 0.04 1 6.08 1 0.14 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0.14 1 0.19 1 TRUE 1 0.13 1 418.77 1 424.94 OK -6.17 47039-STRM 200 PROJECT: Southwood Village 2 DESIGNED BY: CHG HYDRAULIC GRADE LINE ANALYSIS I[MIQ:I [MQU:Z07:7a14141VA 10 Year Checked: INLET OR JUNCTION INLET STATION OUTLET WATER SURFACE ELEV. DIA. PIPE Do (In) DESIGN DISCH. Do (CFS) LENGTH PIPE Lo (Ft) FRICTION SLOPE, Sfo (FT/FT) FRICTION LOSS Hf (Ft) JUNCTION LOSS FINAL H (Ft) Inlet Water Surface Elevation Rim Elev Comments Vo Ho (Ft) Qi V QiVi Vi*2/2g Hi Angle HA Ht 1.3 Ht 0.5 Ht 202 407.55 12 1.09 60.15 0.06% 0.03 4.83 0.09 0.98 4.68 4.57 0.34 0.12 32.01 0.12 0.33 0 TRUE 0.2 407.75 410.54 OK -2.79 204 407.75 12 0.98 94.39 0.04% 0.04 4.68 0.09 0.9 4.58 4.14 0.33 0.11 26.95 0.1 0.3 0 TRUE 0.19 407.94 410.85 OK -2.91 206 1 407.94 12 1 0.9 54.83 1 0.04% 0.02 1 4.58 0.08 0.83 4.47 3.7 0.31 0.11 35.59 0.13 0.32 0 TRUE 0.18 1 408.12 410.78 1 OK -2.66 208 408.12 12 0.83 44.48 0.03% 0.01 4.47 0.08 0.73 4.31 3.15 0.29 0.1 14.39 0.05 0.23 0 TRUE 0.13 408.25 409.83 OK -1.58 210 408.25 12 0.73 35.32 0.02% 0.01 4.31 0.07 0.61 4.09 2.48 0.26 0.09 41.98 0.11 0.27 0 TRUE 0.15 408.4 409.48 OK -1.08 212 408.4 12 0.61 64.32 0.02% 0.01 4.09 0.06 0.39 3.59 1.4 0.2 0.07 29.91 0.07 0.21 0.27 TRUE 0.14 408.54 410.59 OK -2.05 214 408.59 12 0.39 56.43 0.01% 0 3.59 0.05 0.15 3.74 0.57 0.22 0.08 8.06 0.03 0.15 0.2 TRUE 0.1 408.69 413.84 OK -5.14 216 409.35 12 0.15 92.31 0.00% 0 3.74 0.05 0 0 0 0 0 0 0 0.05 0.07 FALSE 0.07 409.42 415.19 OK -5.76 Virginia Runoff Reduction Method! Worksheet DEC, Virginia Runoff Reduction Method New Development Compliance Spreadsheet - Version 3.0 BMP Design Specifications List: 2013 Draft Stds & Specs Site Summary Project Title: Southwood Village Date: 44376 Total Rainfall = 43 inches Site Land Cover Summary A soils BSoils CSoils DSolis Totals %of Total Forest/Open(acres) 0.00 0.00 0.00 0.00 0.00 0 Managed Turf (acres) 1 0.00 2.32 0.00 0.00 2.32 48 Impervious Cover (acres) 1 0.00 2.56 0.00 0.00 2.56 52 4.88 100 Site Tv and Land Cover Nutrient Loads She Rv 0.59 Treatment Volume ft 10,510 TP Load (lb/yr) 6.60 TN Load (lb/yr) 47.24 Total TP Load Reduction Required (lb/yr) 4.60 Site Compliance Summary Total Runoff Volume Reduction (ft) 0 Total TP Load Reduction Achieved (lb/yr) 3.12 Total TN Load Reduction Achieved (Ib/yr) 13.40 Remaining Post Development TP Load 3.48 (Ib/yr) Remaining TP Load Reduction (lb/yr) 148 Required Drainage Area Summary D.A. A D.A. B D.A. C D.A. D D.A. E Total Forest/Open (acres) 0.00 0.00 0.00 0.00 0.00 0.00 Managed Turf(acres) 1.97 0.00 0. 00 0.00 0.00 1.97 Impervious Cover (acres) 2.47 0.00 0.D0 0.00 0.00 2.47 Total Area (acres) 4.44 0.00 0.00 0.00 0.00 4.44 Drainage Area Compliance Summary LA. A D.A. B D.A. C D.A. D DA. E Total TP Load Reduced (lb/yr) 3.12 0.00 0.00 0.00 0.00 3.12 Summary Print Virginia Runoff Reduction Method Worksheet TN Load Reduced (lb/yr) 1 13.40 1 0.00 1 0.00 1 0.00 1 0.00 1 13.40 Drainage Area A Summary Land Cover Summary A Soils BSoils CSolls DSoils Total %ofTotal Forest/Open (acres) 0.00 0.00 0.00 0.00 0.00 0 Managed Turf (acres) 1 0.00 1.97 0.00 1 0.00 1.97 44 Impervious Cover (acres) 1 0.00 2.47 0.00 1 0.00 2.47 56 ) 4.44 BMP Selections Managed Turf Impervious Cover BMPTreatment TIP Load from Untreated TIP Load TPRemoved TPRemaining Downstream Practice Credit Area Credit Area s Volume (k) Upstream to Practice (Ibs) (Ib/yr) (Ih/yr) Treatment to be (acres) (acres) practices (Ibs) Employed Total Impervious Cover Treated (acres) 2.47 Total Turf Area Treated (acres) 1.97 Total TP Load Reduction Achieved in D.A. 3.12 Ib/ r Total TN Load Reduction Achieved in D.A. 13.40 Ib/ r Drainage Area B Summary Land Cover Summary A Soils BSolls CSolls DSolls Total %of Total Forest/Open (acres) 0.00 0.00 0.00 0.00 0.00 0 Managed Turf (acres) 0.00 0.00 0.00 0.00 0.00 0 Impervious Cover (acres) 0.00 0.00 0.00 0.00 0.00 1 0 1 0.00 BMP Selections Managed Turf Impervious Cover BMP Treatment TIP Load from Downstream Practice Credit Area Credit Area s Volume (k) Upstream I Untreated TIP Load to Practice (Ibs) TPRemoved (Ib/yr) TPRemaining (Ih/yr) Treatment to he (aces) (acres) practices (Ibs) Employed Total Impervious Cover Treated (acres) 0.00 Total Turf Area Treated (acres) 0.00 Total TIP Load Reduction Achieved in D.A. (Ib/yr) 0.00 Total TN Load Reduction Achieved in D.A. (Ib/yr) 0.00 Summary Print Virginia Runoff Reduction Method Worksheet Drainage Area C Summary Land Cover Summary A Soils BSolls CSolls DSolls Total %of Total Forest/Open (acres) 0.00 0.00 0.00 0.00 0.00 0 Managed Turf (acres) 0.00 0.00 0.00 0.00 0.00 0 Impervious Cover (acres) 0.00 0.00 0.00 0.00 0.00 0 1 0.00 BMP Selections Managed Turf Impervious Cover BMP TP TP Load from UntreatedTP TP Removed TP Remaining Downstream Practice Credit Area Credit Area s Volume (k) Upstream e(lbs) to Practice (Ibs (lb/yr) (lb/yr) Treatment to he (ayes) (acres) practices (Ibs) Employed Total Impervious Cover Treated (acres) 0.00 Total Turf Area Treated (acres) 0.00 Total TP Load Reduction Achieved in D.A. (Ib/yr) 0.00 Total TN Load Reduction Achieved in D.A. (Ib/yr) 0.00 Drainage Area D Summary Land Cover Summary A Soils BSolls CSOOs DSolls Total %of Total Forest/Open (acres) 0.00 0.00 0.00 0.00 0.00 0 Managed Turf(acres) 0.00 0.00 0.00 1 0.00 0.00 1 0 Impervious Cover (acres) 0.00 0.00 0.00 1 0.00 0.00 1 0 1 0.00 BMP Selections Managed Turf Impervious Cover BMPTreatment TP Load from Untreated TP Load TP Removed TP Remaining Downstream Practice Credit Area Credi[Area s Volume (k) Upstream to Practice (Ibs) (Ib/yr) (Ih/yr) Treatment to he (acres) (acres) practices (Ibs) Employed Total Impervious Cover Treated (acres) 0.00 Total Turf Area Treated (acres) 0.00 Total TP Load Reduction Achieved in D.A. Ib r 0.00 Total TN Load Reduction Achieved in D.A. Ib r 0.00 Summary Print Virginia Runoff Reduction Methotl Worksheet Drainage Area E Summary Land Cover Summary A Soils BSolis CSolls DSoils Total %of Total Forest/Open(acres) 0.00 0.00 DOD 0.00 0.00 0 Managed Turf (acres) 0.00 0.00 0.00 0.00 0.00 0 Impervious Cover (acres) 0.00 0.00 0.00 0.00 0.00 0 1 0.00 BMP Selections Managed Turf Impervious Cover BMP Treatment TIP Load from Untreated TIP Load TIP Removed TP Remaining Downstream Practice Credit Area Credit Area s Volume (k) Upstream to Practice (Ibs) (Ib/yr) (Ih/yr) Treatment to he (acres) (acres) practices (Ibs) Employed Total Impervious Cover Treated (acres) 0.00 Total Turf Area Treated (acres) 0.00 Total TIP Load Reduction Achieved in D.A. 0.00 Ib/ r Total TN Load Reduction Achieved in D.A. 0.00 Ib/ r .__._.__..__._.__..__._.__..__._.__..__._.__..__._..__._.__..__._.__..__._.__..__._.__..__._.__..__._.__..__._.__..__._.__..__._.__, Runoff Volume and CN Calculations 1- arstorm 2-yearstorm 10-yearstorm Target Rainfall Event (in) 1 0.00 0.00 0.00 Drainage Areas RV&CN Drainage Area Drainage Area Drainage Area Drainage Area Drainage Arm ON 82 0 0 0 0 RR (fta) 0 0 0 0 0 1-year return period RV wo RR (m-in) 0.00 0.W 0.00 0.00 0.00 Rvw RR(we-in) 0.00 0.W 0.00 0.00 0.00 CN adjusted 100 0 0 0 0 2-year return period W wo RR(.4n) 0.00 0.00 0.00 0.00 0.00 RVw RR(we-in) 0.00 0.00 0.00 0.00 0.00 CN adjuted 100 0 0 0 0 10-year return period W wo RR(w n) 0.00 0.W OAO 0.00 0.00 RVw RR(ws-in) 0.00 0.W 0.00 0.00 0.00 CN adjusted 100 0 0 0 0 Summary Print 1S 11S Pre Site �ost Routed 12 SWM A Subcat Reach On Link Routing Diagram for Southwood Village 2 Prepared by Timmons Group, Printed 12/212021 FHydroCADO 10.00-20 s/n 06538 0 2017 HydroCAD Software Solutions LLC Southwood Village 2 Prepared by Timmons G Area Listing (all nodes) Area CN Description (acres) (subcatchment-numbers) 2.280 61 >75% Grass cover, Good, HSG B (1S, 11S) 2.470 98 Paved parking, HSG B (11S) 4.140 60 Woods, Fair, HSG B (1S) 8.890 71 TOTAL AREA Printed 12/2/2021 Southwood Village 2 Prepared by Timmons G Soil Listing (all nodes) Area Soil Subcatchment (acres) Group Numbers 0.000 HSG A 8.890 HSG B 1S, 11S 0.000 HSG C 0.000 HSG D 0.000 Other 8.890 TOTAL AREA Printed 12/2/2021 Southwood Village 2 Prepared by Timmons G Ground Covers (all nodes) Printed 12/2/2021 HSG-A HSG-B HSG-C HSG-D Other Total Ground Subcatchment (acres) (acres) (acres) (acres) (acres) (acres) Cover Numbers 0.000 2.280 0.000 0.000 0.000 2.280 >75% Grass cover, Good 1S, 11S 0.000 2.470 0.000 0.000 0.000 2.470 Paved parking 11 S 0.000 4.140 0.000 0.000 0.000 4.140 Woods, Fair 1S 0.000 8.890 0.000 0.000 0.000 8.890 TOTAL AREA Southwood Village 2 Prepared by Timmons G Pipe Listing (all nodes) Printed 12/2/2021 Line# Node In -Invert Out -Invert Length Slope n Diam/Width Height Inside -Fill Number (feet) (feet) (feet) (ft/ft) (inches) (inches) (inches) 1 12P 400.94 399.20 86.8 0.0200 0.013 18.0 0.0 0.0 Southwood Village 2 Type 1124-hr 1-YR Rainfall=3.05" Prepared by Timmons Group Printed 12/2/2021 HVdroCADO 10.00-20 s/n 06538 © 2017 HVdroCAD Software Solutions LLC Paae 6 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Pre Site Runoff Area=4.450 ac 0.00% Impervious Runoff Depth>0.30" Tc=6.0 min CN=60 Runoff=1.93 cfs 0.111 of Subcatchment 11S: Post Routed Runoff Area=4.440 ac 55.63% Impervious Runoff Depth>1.30" Tc=6.0 min CN=82 Runoff=10.86 cfs 0.482 of Pond 12P: SWM A Peak Elev=406.68' Storage=13,332 cf Inflow=10.86 cfs 0.482 of Outflow=0.34 cfs 0.225 of Total Runoff Area = 8.890 ac Runoff Volume = 0.592 of Average Runoff Depth = 0.80" 72.22% Pervious = 6.420 ac 27.78% Impervious = 2.470 ac Southwood Village 2 Prepared by Timmons G Type 1124-hr 1-YR Rainfall=3.05" Printed 12/2/2021 Summary for Subcatchment 1S: Pre Site Runoff = 1.93 cfs @ 12.00 hrs, Volume= 0.111 af, Depth> 0.30" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 1-YR Rainfall=3.05 Area (ac) CN Description 0.000 98 Paved parking, HSG B 0.310 61 >75% Grass cover, Good, HSG B 4.140 60 Woods, Fair, HSG B 4.450 60 Weighted Average 4.450 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment 1S: Pre Site Hydrograph ■ Rurwff 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (houm) Southwood Village 2 Prepared by Timmons G Type 1124-hr 1-YR Rainfall=3.05" Summary for Subcatchment 11S: Post Routed Runoff = 10.86 cfs @ 11.97 hrs, Volume= 0.482 af, Depth> 1.30" Printed 12/2/2021 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 1-YR Rainfall=3.05 Area (ac) CN 2.470 98 Paved parking, HSG B 1.970 61 >75% Grass cover, Good, HSG B 0.000 60 Woods, Fair, HSG B 4.440 82 Weighted Average 1.970 44.37% Pervious Area 2.470 55.63% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment 11S: Post Routed Hydrograph ■ Rurwff Time (hours) Southwood Village 2 Prepared by Timmons G Type 1124-hr 1-YR Rainfall=3.05" Summary for Pond 12P: SWM A Printed 12/2/2021 Inflow Area = 4.440 ac, 55.63% Impervious, Inflow Depth > 1.30" for 1-YR event Inflow = 10.86 cfs @ 11.97 hrs, Volume= 0.482 of Outflow = 0.34 cfs @ 14.64 hrs, Volume= 0.225 af, Atten= 97%, Lag= 160.2 min Primary = 0.34 cfs @ 14.64 hrs, Volume= 0.225 of Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 406.68' @ 14.64 hrs Surf.Area= 6,150 sf Storage= 13,332 cf Plug -Flow detention time= 241.7 min calculated for 0.225 of (47% of inflow) Center -of -Mass det. time= 158.4 min ( 950.1 - 791.8 ) Volume Invert Avail.Storage Storage Description #1 404.00' 29,950 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 404.00 3,790 0 0 409.00 8,190 29,950 29,950 Device Routing Invert Outlet Devices #1 Primary 400.94' 18.0" Round Culvert L= 86.8' RCP, groove end projecting, Ke= 0.200 Inlet / Outlet Invert= 400.94' / 399.20' S= 0.0200 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf #2 Device 1 404.00' 2.5" W x 2.5" H Vert. Orifice/Grate C= 0.600 #3 Device 1 406.75' 36.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads #4 Primary 407.50' 45.0' long x 9.0' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.46 2.55 2.70 2.69 2.68 2.68 2.67 2.64 2.64 2.64 2.65 2.64 2.65 2.65 2.66 2.67 2.69 Primary OutFlow Max=0.34 cfs @ 14.64 hrs HW=406.68' (Free Discharge) 1_Cu lvert (Passes 0.34 cfs of 20.78 cfs potential flow) �2=Orifice/Grate (Orifice Controls 0.34 cfs @ 7.73 fps) 3=Orifice/Grate ( Controls 0.00 cfs) =Broad -Crested Rectangular Weir ( Controls 0.00 cfs) Southwood Village 2 Prepared by Timmons 1 Pond 12P: SWM A Hydrograph Type 1124-hr 1-YR Rainfall=3.05" Printed 12/2/2021 ■ Ir—MM —11 ■ Primary Lim MMMMM J MMMMMMM .----- ------- .---..1 ------ MMMMM 11 MMMMM //% ------ Southwood Village 2 Type/1 24-hr 10-YR Rainfall=5.58" Prepared by Timmons Group Printed 12/2/2021 HVdroCADO 10.00-20 s/n 06538 © 2017 HVdroCAD Software Solutions LLC Paoe 11 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Pre Site Runoff Area=4.450 ac 0.00% Impervious Runoff Depth>1.48" Tc=6.0 min CN=60 Runoff=12.57 cfs 0.550 of Subcatchment 11S: Post Routed Runoff Area=4.440 ac 55.63% Impervious Runoff Depth>3.36" Tc=6.0 min CN=82 Runoff=26.92 cfs 1.241 of Pond 12P: SWM A Peak Elev=407.55' Storage=18,984 cf Inflow=26.92 cfs 1.241 of Outflow=22.76 cfs 0.927 of Total Runoff Area = 8.890 ac Runoff Volume = 1.792 of Average Runoff Depth = 2.42" 72.22% Pervious = 6.420 ac 27.78% Impervious = 2.470 ac Southwood Village 2 Prepared by Timmons G Type/1 24-hr 10-YR Rainfall=5.58" Printed 12/2/2021 Summary for Subcatchment 1S: Pre Site Runoff = 12.57 cfs @ 11.98 hrs, Volume= 0.550 af, Depth> 1.48" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10-YR Rainfall=5.58" Area (ac) CN Description 0.000 98 Paved parking, HSG B 0.310 61 >75% Grass cover, Good, HSG B 4.140 60 Woods, Fair, HSG B 4.450 60 Weighted Average 4.450 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment 1S: Pre Site Hydrograph I ----- -----Runoff ------ff MMMMMMM s _ ' M�-- Runo D�pth"j�Pffl ---- .......� ...... %,....,.,,,,,,.,.,,,,,,,,,,,,,,,,,,,� 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) ■ Rurwff Southwood Village 2 Prepared by Timmons G Type/1 24-hr 10-YR Rainfall=5.58" Summary for Subcatchment 11S: Post Routed Runoff = 26.92 cfs @ 11.97 hrs, Volume= 1.241 af, Depth> 3.36" Printed 12/2/2021 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10-YR Rainfall=5.58" Area (ac) CN 2.470 98 Paved parking, HSG B 1.970 61 >75% Grass cover, Good, HSG B 0.000 60 Woods, Fair, HSG B 4.440 82 Weighted Average 1.970 44.37% Pervious Area 2.470 55.63% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment 11S: Post Routed Hydrograph ■ Runoff Time (hours) Southwood Village 2 Prepared by Timmons G Type/1 24-hr 10-YR Rainfall=5.58" Summary for Pond 12P: SWM A Printed 12/2/2021 Inflow Area = 4.440 ac, 55.63% Impervious, Inflow Depth > 3.36" for 10-YR event Inflow = 26.92 cfs @ 11.97 hrs, Volume= 1.241 of Outflow = 22.76 cfs @ 12.02 hrs, Volume= 0.927 af, Atten= 15%, Lag= 3.1 min Primary = 22.76 cfs @ 12.02 hrs, Volume= 0.927 of Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 407.55' @ 12.02 hrs Surf.Area= 6,912 sf Storage= 18,984 cf Plug -Flow detention time= 98.5 min calculated for 0.924 of (74% of inflow) Center -of -Mass det. time= 37.7 min ( 808.7 - 771.0 ) Volume Invert Avail.Storage Storage Description #1 404.00' 29,950 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 404.00 3,790 0 0 409.00 8,190 29,950 29,950 Device Routing Invert Outlet Devices #1 Primary 400.94' 18.0" Round Culvert L= 86.8' RCP, groove end projecting, Ke= 0.200 Inlet / Outlet Invert= 400.94' / 399.20' S= 0.0200 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf #2 Device 1 404.00' 2.5" W x 2.5" H Vert. Orifice/Grate C= 0.600 #3 Device 1 406.75' 36.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads #4 Primary 407.50' 45.0' long x 9.0' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.46 2.55 2.70 2.69 2.68 2.68 2.67 2.64 2.64 2.64 2.65 2.64 2.65 2.65 2.66 2.67 2.69 Primary OutFlow Max=21.45 cfs @ 12.02 hrs HW=407.52' (Free Discharge) 1_Cu lvert (Passes 21.16 cfs of 22.18 cfs potential flow) �2=Orifice/Grate (Orifice Controls 0.39 cfs @ 8.90 fps) 3=Orifice/Grate (Weir Controls 20.78 cfs @ 2.87 fps) =Broad -Crested Rectangular Weir (Weir Controls 0.29 cfs @ 0.34 fps) Southwood Village 2 Prepared by Timmons 1 30 28 26 24 22 20 18 16 0 14 LL 12 10 8 6 4 2 0 Type 1124-hr 10-YR Rainfall=5.58" Printed 12/2/2021 Pond 12P: SWM A Hydrograph / ----- E 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) ■ Inflow ■ Primary Southwood Village 2 Type II 24-hr 100-YR Rainfall=9.16" Prepared by Timmons Group Printed 12/2/2021 HVdroCADO 10.00-20 s/n 06538 © 2017 HVdroCAD Software Solutions LLC Paoe 16 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Pre Site Runoff Area=4.450 ac 0.00% Impervious Runoff Depth>3.88" Tc=6.0 min CN=60 Runoff=32.44 cfs 1.438 of Subcatchment 11S: Post Routed Runoff Area=4.440 ac 55.63% Impervious Runoff Depth>6.53" Tc=6.0 min CN=82 Runoff=50.24 cfs 2.417 of Pond 12P: SWM A Peak Elev=407.88' Storage=21,319 cf Inflow=50.24 cfs 2.417 of Outflow=49.33 cfs 2.097 of Total Runoff Area = 8.890 ac Runoff Volume = 3.854 of Average Runoff Depth = 5.20" 72.22% Pervious = 6.420 ac 27.78% Impervious = 2.470 ac Southwood Village 2 Prepared by Timmons G Type II 24-hr 100-YR Rainfall=9.16" Printed 12/2/2021 Summary for Subcatchment 1S: Pre Site Runoff = 32.44 cfs @ 11.97 hrs, Volume= 1.438 af, Depth> 3.88" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 100-YR Rainfall=9.16" Area (ac) CN Description 0.000 98 Paved parking, HSG B 0.310 61 >75% Grass cover, Good, HSG B 4.140 60 Woods, Fair, HSG B 4.450 60 Weighted Average 4.450 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment 1S: Pre Site Hydrograph ■ Rurwff 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Southwood Village 2 Prepared by Timmons G Type II 24-hr 100-YR Rainfall=9.16" Summary for Subcatchment 11S: Post Routed Runoff = 50.24 cfs @ 11.96 hrs, Volume= 2.417 af, Depth> 6.53" Printed 12/2/2021 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 100-YR Rainfall=9.16" Area (ac) CN 2.470 98 Paved parking, HSG B 1.970 61 >75% Grass cover, Good, HSG B 0.000 60 Woods, Fair, HSG B 4.440 82 Weighted Average 1.970 44.37% Pervious Area 2.470 55.63% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment 11S: Post Routed Hydrograph ■ Rurwff Time (hours) Southwood Village 2 Prepared by Timmons G Type II 24-hr 100-YR Rainfall=9.16" Summary for Pond 12P: SWM A [82] Warning: Early inflow requires earlier time span Printed 12/2/2021 Inflow Area = 4.440 ac, 55.63% Impervious, Inflow Depth > 6.53" for 100-YR event Inflow = 50.24 cfs @ 11.96 hrs, Volume= 2.417 of Outflow = 49.33 cfs @ 11.99 hrs, Volume= 2.097 af, Atten= 2%, Lag= 1.3 min Primary = 49.33 cfs @ 11.99 hrs, Volume= 2.097 of Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 407.88' @ 11.99 hrs Surf.Area= 7,203 sf Storage= 21,319 cf Plug -Flow detention time= 68.6 min calculated for 2.090 of (86% of inflow) Center -of -Mass det. time= 27.0 min ( 782.8 - 755.8 ) Volume Invert Avail.Storage Storage Description #1 404.00' 29,950 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 404.00 3,790 0 0 409.00 8,190 29,950 29,950 Device Routino Invert Outlet Devices #1 Primary 400.94' 18.0" Round Culvert L= 86.8' RCP, groove end projecting, Ke= 0.200 Inlet / Outlet Invert= 400.94' / 399.20' S= 0.0200 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf #2 Device 1 404.00' 2.5" W x 2.5" H Vert. Orifice/Grate C= 0.600 #3 Device 1 406.75' 36.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads #4 Primary 407.50' 45.0' long x 9.0' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.46 2.55 2.70 2.69 2.68 2.68 2.67 2.64 2.64 2.64 2.65 2.64 2.65 2.65 2.66 2.67 2.69 Primary OutFlow Max=47.74 cfs @ 11.99 hrs HW=407.86' (Free Discharge) 1_Cu lvert (Barrel Controls 22.73 cfs @ 12.87 fps) �2=Orifice/Grate (Passes < 0.41 cfs potential flow) 3=Orifice/Grate (Passes < 35.92 cfs potential flow) =Broad -Crested Rectangular Weir (Weir Controls 25.00 cfs @ 1.53 fps) Southwood Village 2 Prepared by Timmons 1 0 LL Pond 12P: SWM A Hydrograph Time (hours) Type 1124-hr 100-YR Rainfall=9.16" Printed 12/2/2021 1 1 1 1 1 1 1 1 1 j, y ■ Inflow ■ Primary