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Committee of the Whole/Documents/Appendix B: Stormwater Calculation - 10-Year and 100-Year Events
Appendix

Appendix B: Stormwater Calculation - 10-Year and 100-Year Events

June 13, 2023Pages 132–1342 sections

Data tables detailing runoff storage requirements and peak detention volumes for 10-year and 100-year storm events.

2. APPROVAL OF AGENDA (motion to approve)
10-year required storage = 22.2 m3100-year peak runoff rate = 0.084 m3/sContributing area = 1.22 ha

APPENDIX B

Page 132–134

STORMWATER CALCULATION 10-YEAR AND 100-YEAR EVENTS

Underground Utilities Brief | Prepared for Boardwalk REIT 339 / 341 / 345 Island Highway, View Royal, BC

RUNOFF STORAGE REQUIREMENTS

Project Name: 3339 Island Hwy Project File #: 2241-22149 Date: 1/19/2023

Area: View Royal Pre-development Conditions
IDF Curve: Victoria Gonzales # 1018611 10 Year
Contributing Area (ha) = 1.22 Time of Concentration Tc = 15.00 min.
Post Development C = 0.76 Coefficient of Runoff C = 0.52
Return Period 10 Year Intensity I = 21.21 mm
Rational Method Q=CIA/360 Contributing Area A = 1.22 ha
Pre-Development Runoff = 0.0374 m³/s
(A) RAINFALL DURATION (min.) (B) RAINFALL INTENSITY (mm/hr) (C) PEAK RUNOFF RATE (m³/s) (D) STORM RUNOFF VOLUME (m³) (E) ACCUM. RUNOFF VOLUME (m³) (F) CONTROLLED RELEASE VOLUME (m³) (G) ACCUM. RELEASE VOLUME (m³) (H) PEAK DETENTION VOLUME (m³)
15 21.21 0.055 49.27 49.27 33.67 33.67 15.60
20 18.78 0.048 14.54 63.81 11.22 44.89 18.92
25 17.09 0.044 13.23 77.04 11.22 56.11 20.93
30 15.82 0.041 12.25 89.29 11.22 67.33 21.96
35 14.82 0.038 11.48 100.77 11.22 78.56 22.21 <=
40 14.01 0.036 10.85 111.61 11.22 89.78 21.84
45 13.33 0.034 10.32 121.93 11.22 101.00 20.93
50 12.75 0.033 9.87 131.80 11.22 112.22 19.58
55 12.24 0.032 9.48 141.28 11.22 123.44 17.84
60 11.80 0.030 9.14 150.42 11.22 134.67 15.75
65 11.41 0.029 8.83 159.25 11.22 145.89 13.36
70 11.06 0.029 8.56 167.81 11.22 157.11 10.70
75 10.74 0.028 8.31 176.12 11.22 168.33 7.79
80 10.45 0.027 8.09 184.21 11.22 179.55 4.66
85 10.18 0.026 7.88 192.10 11.22 190.78 1.32
90 9.94 0.026 7.70 199.80 11.22 202.00
95 9.72 0.025 7.52 207.32 11.22 213.22
100 9.51 0.025 7.36 214.68 11.22 224.44
105 9.31 0.024 7.21 221.89 11.22 235.67
110 9.13 0.024 7.07 228.96 11.22 246.89
115 8.96 0.023 6.94 235.90 11.22 258.11
120 8.80 0.023 6.81 242.71 11.22 269.33
130 8.51 0.022 13.18 255.89 22.44 291.78
140 8.25 0.021 12.77 268.66 22.44 314.22
150 8.01 0.021 12.40 281.06 22.44 336.67
160 7.79 0.020 12.07 293.13 22.44 359.11
170 7.60 0.020 11.76 304.89 22.44 381.55
180 7.41 0.019 11.48 316.37 22.44 404.00
240 6.56 0.017 61.00 377.37 134.67 538.66
300 5.97 0.015 55.50 432.87 134.67 673.33
360 5.53 0.014 51.38 484.25 134.67 808.00
480 4.90 0.013 90.99 575.24 269.33 1077.33
600 4.46 0.011 82.79 658.03 269.33 1346.66

Peak Storage Volume (H) = G - E Controled Release Volume (F) = Pre-development Runoff (R) x Rainfall Duration (A) x 60 Storm Runoff Volume (D) = Peak Runoff Rate (C) x Rainfall Duration (A) x 60

RUNOFF STORAGE REQUIREMENTS

Project Name: 3339 Island Hwy Project File #: 2241-22149 Date: 1/19/2023

Area: View Royal Pre-development Conditions
IDF Curve: Victoria Gonzales # 1018611 100 Year
Contributing Area (ha) = 1.22 Time of Concentration Tc = 15.00 min.
Post Development C = 0.81 +0.05 Coefficient of Runoff C = 0.57 +0.05
Return Period 100 Year Intensity I = 30.69 mm
Rational Method Q=CIA/360 Contributing Area A = 1.22 ha
Pre-Development Runoff = 0.0593 m³/s
(A) RAINFALL DURATION (min.) (B) RAINFALL INTENSITY (mm/hr) (C) PEAK RUNOFF RATE (m³/s) (D) STORM RUNOFF VOLUME (m³) (E) ACCUM. RUNOFF VOLUME (m³) (F) CONTROLLED RELEASE VOLUME (m³) (G) ACCUM. RELEASE VOLUME (m³) (H) PEAK DETENTION VOLUME (m³)
15 30.69 0.084 75.96 75.96 53.39 53.39 22.57
20 27.15 0.075 22.40 98.37 17.80 71.19 27.18
25 24.68 0.068 20.37 118.74 17.80 88.99 29.75
30 22.84 0.063 18.85 137.58 17.80 106.78 30.80 <=
35 21.39 0.059 17.65 155.23 17.80 124.58 30.65
40 20.21 0.056 16.67 171.91 17.80 142.38 29.53
45 19.22 0.053 15.86 187.76 17.80 160.18 27.59
50 18.37 0.051 15.16 202.92 17.80 177.97 24.95
55 17.64 0.049 14.56 217.48 17.80 195.77 21.71
60 17.00 0.047 14.03 231.51 17.80 213.57 17.94
65 16.43 0.045 13.56 245.07 17.80 231.37 13.70
70 15.92 0.044 13.14 258.21 17.80 249.16 9.04
75 15.46 0.043 12.76 270.96 17.80 266.96 4.00
80 15.04 0.041 12.41 283.37 17.80 284.76
85 14.66 0.040 12.09 295.47 17.80 302.55
90 14.30 0.039 11.80 307.27 17.80 320.35
95 13.98 0.038 11.53 318.81 17.80 338.15
100 13.68 0.038 11.29 330.09 17.80 355.95
105 13.39 0.037 11.05 341.14 17.80 373.74
110 13.13 0.036 10.84 351.98 17.80 391.54
115 12.88 0.035 10.63 362.61 17.80 409.34
120 12.65 0.035 10.44 373.05 17.80 427.14
130 12.23 0.034 20.18 393.24 35.59 462.73
140 11.85 0.033 19.56 412.79 35.59 498.32
150 11.51 0.032 18.99 431.78 35.59 533.92
160 11.19 0.031 18.47 450.26 35.59 569.51
170 10.91 0.030 18.00 468.26 35.59 605.11
180 10.65 0.029 17.57 485.83 35.59 640.70
240 9.42 0.026 93.26 579.10 213.57 854.27
300 8.56 0.024 84.81 663.90 213.57 1067.84
360 7.92 0.022 78.47 742.37 213.57 1281.41
480 7.01 0.019 138.84 881.21 427.14 1708.54
600 6.37 0.018 126.25 1007.46 427.14 2135.68

Peak Storage Volume (H) = G - E Controled Release Volume (F) = Pre-development Runoff (R) x Rainfall Duration (A) x 60 Storm Runoff Volume (D) = Peak Runoff Rate (C) x Rainfall Duration (A) x 60

Page 132–134
Extracted from: 2023 06 13 Committee of the Whole Agenda - Agenda - Pdf