Preliminary Stormwater Management Report - …...Preliminary Stormwater Management Report Jp2g Consultants Inc. ENGINEERS PLANNERS PROJECT MANAGERS Jp2g Consultants Inc. ENGINEERS

KDSA DEVELOPMENT-BRAEBURN ESTATES Preliminary Stormwater Management Report

Jp2g Consultants Inc.

ENGINEERS ▪ PLANNERS ▪ PROJECT MANAGERS

Jp2g Consultants Inc. ENGINEERS PLANNERS PROJECT MANAGERS

1150 Morrison Drive, Suite 410, Ottawa, ON K2H 8S9

T 613-828-7800, F 613-828-2600, www.jp2g.com

1150 Morrison Drive, Suite 410 Ottawa, ON, K2H 8S9

T.613.828.7800 F.613.828.2600 Project No. 2141686A

Preliminary Stormwater Management Report

Braeburn Estates Township of McNab/Braeside, Ontario

Prepared for

Susan Anglin

KDSA Development Corporation




TABLE OF CONTENTS

1.0 Introduction............................................................................................................................................... 1

2.0 Objective ................................................................................................................................................... 1

3.0 Criteria used in analysis ............................................................................................................................. 1

4.0 Pre-development Conditions ..................................................................................................................... 1

4.1 Existing Site Drainage .......................................................................................................................................... 1

4.2 Estimated Allowable Release Rates ................................................................................................................... 2

5.0 Post-development Conditions ................................................................................................................... 2

5.1 Proposed Site Drainage ....................................................................................................................................... 2

5.2 Proposed Release Rates ...................................................................................................................................... 3

6.0 Stormwater Management ......................................................................................................................... 3

6.1 Quality .................................................................................................................................................................. 3

6.2 Quantity ............................................................................................................................................................... 4

7.0 Sediment and Erosion Control ................................................................................................................... 4

8.0 Conclusion ................................................................................................................................................. 4

LIST OF TABLES

Table 4.1 Summary of Pre-development Drainage Area Information .............................................................. 1 Table 4.2 Pre-development Times of Concentration (minutes) ...................................................................... 2 Table 4.3 Pre-development Estimated Allowable Release Rates ..................................................................... 2 Table 5.1 Summary of Post-development Drainage Area Information ............................................................. 3 Table 5.2 Post-development Times of Concentration (minutes) ...................................................................... 3 Table 5.3 Post-development Release Rates .................................................................................................... 3

LIST OF FIGURES

Figure 1 Site Location Map ...................................................................................................... [End of Report] Figure 2 Pre-development Drainage Area Plan ......................................................................... [End of Report] Figure 3 Post-development Drainage Area Plan ....................................................................... [End of Report]

LIST OF APPENDICES

Appendix A Pre-development Hydrology Calculations ................................................................... [End of Report] Appendix B Post-development Hydrology Calculations ................................................................. [End of Report]

KDSA DEVELOPMENT CORPORATION – BRAEBURN ESTATES Preliminary Stormwater Management Overview

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1.0 Introduction This preliminary stormwater management report examines the potential stormwater runoff impacts of the proposed Braeburn Estates Lot Development, located at the end of Building Supply Road off of Burnstown Road in Burnstown, Ontario. This report is intended to assess the stormwater impacts of this proposed development on the surrounding properties and drainage network. The total area of the site is approximately 21.7 hectares. The proposed development includes approximately 1.2km of paved two‐lane roadway, twenty‐seven (27) single family homes, and areas designated for public green space.

2.0 Objective The objective of this stormwater management report is to provide a hydrological analysis of the existing and proposed site and, in general, confirm that post‐development peak flows will not adversely impact the existing stormwater conveyance system.

3.0 Criteria used in analysis The stormwater analysis criteria used in this report is to ensure that the existing peak flows are not significantly increased as a result of this subdivision development. Where post‐development flows exceed pre‐development flows, proposed storage options are included to alleviate any negative impacts due to the development. The Rational Method (Q = 2.78CiA) was chosen to calculate the pre‐ and post‐development release rates for this site. Detailed stormwater management calculations are included in Appendices A and B for the pre‐ and post‐development scenarios, respectively. The rainfall intensities used in this analysis are based on the City of Ottawa IDF curve equations, as per the City of Ottawa Sewer Design Guidelines, 2012.

4.0 Pre-development Conditions 4.1 Existing Site Drainage

The existing undeveloped site is mainly wooded and sloped north‐west, draining toward the Madawaska River. The site is contoured with elevated areas separating drainage areas with the overland flow and rivulet paths. There is an average approximate elevation drop of 37 meters from the eastern property line to the western property line at the Madawaska River, which is due to portions of the property having steep sloping banks, with bedrock outcrops, toward the Madawaska River. A variable slope stability setback has been determined for development layout and slope stability purposes. The average length of water travel across the six drainage areas is approximately 215 meters. The total site and upstream area is approximately 61.6 hectares and is divided into six (6) drainage areas, as shown in Figure 2 and described below in Table 4.1. Table 4.1 ‐ Summary of Pre‐development Drainage Area Information

Area ID Drainage Area (ha) Runoff Coefficient (Co)

5‐Year 100‐Year

A1 2.09 0.33 0.41

A2 13.22 0.33 0.41

A3 11.69 0.32 0.40

A4 16.13 0.32 0.40

A5 8.92 0.32 0.40

A6 9.52 0.32 0.40

Total 61.57 ‐‐ ‐‐



ENGINEERS ▪ PLANNERS ▪ PROJECT MANAGERS page 2 of 4

When using the Rational Method to estimate stormwater flows, two factors which affect the magnitude of flow are the Time of Concentration (Tc) and the Runoff Coefficient (C). The Runoff Coefficient is a function of land use, soil type, and slope. According to the MTO Drainage Management Manual (DMM), the Runoff Coefficient for woodland area with high sloped topography ranges from C=0.30 to C=0.60 depending on the soil type. The geotechnical investigation, completed as part of the Geotechnical Slope Stability assessment for the proposed development by Paterson Group (Dec. 2014), found that the sub-surface condition generally consists of topsoil underlain by sandy-silt perched atop an igneous bedrock. In accordance with the MTO DMM, the time of concentration is estimated by using the Airport Formula if the runoff coefficient is less than or equal to 0.4 and the Bransby Williams Formula if the runoff coefficient is greater than 0.4. In the event that the calculated time of concentration is less than 10 minutes, 10 minutes was used. A summary of calculated time of concentration values, adjusted for the 5- and 100-year storms, is provided in Table 4.2. Table 4.2 - Pre-development Times of Concentration (minutes)

Storm Event A1 A2 A3 A4 A5 A6

5-Year 18 31 30 35 22 29

100-Year 10 * 16 27 31 20 26

* Time of concentration values that are estimated to be less than 10 minutes - 10 minutes is used.

4.2 Estimated Allowable Release Rates

Based on pre-development conditions, runoff coefficients (Table 4.1), and the times of concentration (Table 4.2), the estimated allowable release rates have been calculated. The results of this analysis has been summarized Table 4.3 for the 5- and 100-year storms. Table 4.3 - Pre-development Estimated Allowable Release Rates

Storm Event Allowable (pre-development) Release Rate (L/s)

A1 A2 A3 A4 A5 A6 Total

5-Year 119 758 637 879 486 635 3,515

100-Year 375 2,375 2,016 2,782 1,539 1,641 10,728

Detailed stormwater management calculations for the pre-development scenario are included in Appendix A.

5.0 Post-development Conditions

5.1 Proposed Site Drainage

The proposed subdivision includes a two-lane roadway approximately 1.2km long, with 27 single family homes including paved driveways, and a public green space. The side and rear of the lots will maintain natural sheet drainage towards the river. The post-development (61.57 ha) drainage area plan is provided as Figure 3. The post-development drainage pattern utilizes the (existing) natural slopes within the site as best as possible. Table 5.1 provides a summary of drainage area information including area in hectares and weighted runoff coefficients.



ENGINEERS ▪ PLANNERS ▪ PROJECT MANAGERS page 3 of 4

Table 5.1 - Summary of Post-development Drainage Area Information

Area ID Drainage Area (ha) Runoff Coefficient (Co)

5-Year 100-Year

B1 1.61 0.34 0.42

B2 2.60 0.33 0.41

B3 3.67 0.33 0.41

B4 1.79 0.34 0.42

B5 4.36 0.33 0.41

B6 33.47 0.33 0.41

B7 4.78 0.38 0.46

B8 9.29 0.32 0.40

Total 61.57 -- --

A summary of the time of concentration values that have been calculated for the post-development scenario is provided below, in Table 5.2. Table 5.2 - Post-development Times of Concentration (minutes)

Storm Event B1 B2 B3 B4 B5 B6 B7 B8

5-Year 18 13 18 15 14 34 26 27

100-Year 10 * 10 * 10 * 10 * 10 * 18 11 24

* Time of concentration values that are estimated to be less than 10 minutes - 10 minutes is used.

5.2 Proposed Release Rates

Based on the post-development runoff coefficients and the times of concentration, the proposed release rates are summarized below in Table 5.3. Table 5.3 - Post-development Release Rates

Storm Event Release Rate (L/s)

B1 B2 B3 B4 B5 B6 B7 B8 Total

5-Year 122 189 266 133 315 2,477 405 654 4,561

100-Year 337 527 741 370 880 6,883 1,102 1,833 12,672

Detailed stormwater management calculations for the post-development scenario are included in Appendix B.

6.0 Stormwater Management

6.1 Quality

Quality control will be provided using a treatment train approach with Best Management Practices (BMP’s). BMP options to address quality control at the site in post-development conditions include plunge pools, grass-lined swales, or rock check dams. The quality control measures will be designed during the detailed design stage.




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Madawaska RiverCALABOGIE ROAD

BURNSTOWN ROAD

MCLEOD ROAD

MCLACHLAN ROAD

DICKSON ROAD

LOWER SPRUCE HEDGE ROAD

JESSIE ROAD

LECKIE LANE

RIOPELLE ROAD

LORLEI DRIVE KIPPEN ROAD

PICKET HILL LANE

MCVICAR LANE

PEGGS LANE

CHRIS

LANE

CLOUTH

IER LANE

BUILDING SUPPLY ROAD

MERVIN LANE

BURNSTOWN ROAD

LOT 16CON 1

LOT 16CON 1

LOT 15CON 4

LOT 16CON 2

LOT 14CON 2

LOT 18CON 2

LOT 19CON 2

LOT 15CON 1

LOT 18CON 1

LOT 20CON 1

LOT 15CON 2

LOT 13CON 2

LOT 19CON 1

LOT 14CON 3

LOT 15CON 3

LOT 12CON 3

LOT 13CON 3

LOT 14CON 4

LOT 17CON 3

LOT 18CON 3

LOT 14CON 1

LOT 20CON 2

LOT 16CON 3

LOT 18CON 1

LOT 11CON 3

LOT 12CON 2

LOT 21CON 1

LOT 17CON 1

LOT 17CON 1

LOT 15CON 1

LOT 13CON 4

LOT 16CON 4

LOT 16CON 4LOT 17CON 4

LOT 19CON 1

LOT 17CON 1

LOT 19CON 3 LOT 15CON 5LOT 21CON 2

LOT 16CON 3

LOT 13CON 1 LOT 11CON 2

LOT 17CON 2

LOT 17CON 2

LOT 17CON 1

LOT 12CON 4

LOT 17CON 3

LOT 14CON 1 LOT 10CON 3LOT 16CON 2LOT 17CON 2

LOT 16CON 5

LOT 17CON 2

LOT 18CON 4

Braeburn Estates SubdivisionLot 17 Concession 2 Township of McNab

Drawn By: PJChecked by: KMDate: July 2015

Figure 1 - Site Location Map

Project: 2133134A

Data from Land Information Ontario 0 500 1,000250 Meters

1:20,000

Legend

Study Area# Building Symbol

Contour

Utility Line

Road Segment

Railway

Lot Fabric

Township Boundary

Building

Wetland

Waterbody

Watercourse

Wooded Area

®




Appendix A Pre-development Stormwater Management Calculations

Soil Type: Soil Description HSG Land Use and Treatment: Condition Vegetation: Topography RC

Hard Surface Impervious Sandy, Sandy Loams and Gravels: Shallow, Overlying Percambrian bedrock or Clay Subsoil B Paved parking lots, roofs, driveways etc Paved or Roofs 0.90Woodland & Forest Sandy, Sandy Loams and Gravels: Shallow, Overlying Percambrian bedrock or Clay Subsoil B Woodlots and Forest Woodland: Rolling (5-10% Slope) 0.32

Open Space Sandy, Sandy Loams and Gravels: Shallow, Overlying Percambrian bedrock or Clay Subsoil B Open Space (Lawns, Golf Courses, Cemeteries, etc.): Fair (grass cover 50% to 75%) Pasture: Rolling (5-10% Slope) 0.29Gravel Sandy, Sandy Loams and Gravels: Shallow, Overlying Percambrian bedrock or Clay Subsoil B Gravel (including ROW) Gravel 0.40

TABLE A-1: PRE-DEVELOPMENT SOIL AND RUNOFF COEFFICIENT DATA

Runoff CoefficientCurve NumberHydrologic Soils Group

User Input: Land Use Name

<= 10-Year25-Year Increase

(10%)

50-Year Increase

(20%)

100-Year Increase

(25%)<= 10-Year 25-Year 50-Year 100-Year

0.05 0.90 0.99 1.00 1.00

2.04 0.32 0.35 0.38 0.40

0.00 0.29 0.32 0.35 0.37

0.00 0.40 0.44 0.48 0.50

0.46 0.90 0.99 1.00 1.00

10.61 0.32 0.35 0.38 0.40

2.15 0.29 0.32 0.35 0.37

0.00 0.40 0.44 0.48 0.50

0.00 0.90 0.99 1.00 1.00

11.69 0.32 0.35 0.38 0.40

0.00 0.29 0.32 0.35 0.37

0.00 0.40 0.44 0.48 0.50

0.00 0.90 0.99 1.00 1.00

16.13 0.32 0.35 0.38 0.40

0.00 0.29 0.32 0.35 0.37

0.00 0.40 0.44 0.48 0.50

0.00 0.90 0.99 1.00 1.00

8.92 0.32 0.35 0.38 0.40

0.00 0.29 0.32 0.35 0.37

0.00 0.40 0.44 0.48 0.50

0.00 0.90 0.99 1.00 1.00

9.52 0.32 0.35 0.38 0.40

0.00 0.29 0.32 0.35 0.37

0.00 0.40 0.44 0.48 0.50

Woodland & ForestOpen Space

Gravel

0.32 0.35 0.38 0.40A6 9.52 NashHyd

Hard Surface Impervious

TABLE A-2: PRE-DEVELOPMENT DRAINAGE AREA PARAMETERS AND DATA

Weighted Runoff Coefficient

0.36 0.40 0.410.33

Land Use Area (ha)

Runoff Coefficient

A2 13.22 NashHyd


Drainage Area ID

Gravel


Land UseArea (ha) Command

A1 2.09 NashHydWoodland & Forest

Open Space


Gravel

0.37 0.40 0.410.33


Gravel

0.35 0.38 0.400.32


A4 16.13 NashHyd


A3 11.69 NashHyd

A5 8.92 NashHyd



Gravel

0.35 0.38 0.400.32


Gravel

0.35 0.38 0.400.32

Sw = 100 * (∆h - hf)0.75L - Lf

Where:Sw = watershed slope, %

∆h =

hf = sum of heights of rapids and waterfalls between 10% and 85% points, m.L = the total length of the main channel, includes the undefined flow path, to head of basin, m.Lf = the sum of lengths of rapids and waterfalls, up to 10% of L, m.

A1 NashHyd 195.15 158.55 36.6 9.71 278.87 11.08 13.58 HillyA2 NashHyd 205.07 168.20 36.9 11.12 539.86 3.20 6.41 RollingA3 NashHyd 203.94 166.67 37.3 0 574.27 0 8.65 RollingA4 NashHyd 199.91 164.23 35.7 11.36 582.53 15.03 5.76 RollingA5 NashHyd 185.37 148.67 36.7 0 392.47 0 12.47 HillyA6 NashHyd 193.09 161.56 31.5 0 505.37 0 8.32 Rolling

Total Height

Difference (m)

Drainage AreaID

Main Channel Length

(m)

Command Drainage Area Topography

85% Elevation

(m)

Waterfalls Length

10% Elevation

(m)

Waterfalls Height

Slope, Sw

(%)

TABLE A-3: PRE-DEVELOPMENT WATERSHED SLOPE - 85/10 METHOD

difference in elevation, m, between the 85% point and the 10% point obtained from contours, airphotos, etc.

The Airport Formula The Bransby Williams Formula

tc = 3.26 (1.1-C) L0.5 tc = 0.057*LSw

0.33 (Sw0.2 * A 0.1)

where: tc = time of concentration, min. where tc = time of concentration, min.C = runoff coefficient C = runoff coefficientSw = watershed slope, % Sw = watershed slope, %L = watershed length, m. L = watershed length, m.

A1 2.09 NashHyd 0.33 0.36 0.40 0.41 13.58 278.87 18 17 16 9A2 13.22 NashHyd 0.33 0.37 0.40 0.41 6.41 539.86 31 30 29 16A3 11.69 NashHyd 0.32 0.35 0.38 0.40 8.65 574.27 30 29 28 27A4 16.13 NashHyd 0.32 0.35 0.38 0.40 5.76 582.53 35 33 32 31A5 8.92 NashHyd 0.32 0.35 0.38 0.40 12.47 392.47 22 21 20 20A6 9.52 NashHyd 0.32 0.35 0.38 0.40 8.32 505.37 29 27 26 26

50-Year 100-Year <=10-Year

TABLE A-4: PRE-DEVELOPMENT TIME OF CONCENTRATION

25-Year 50-Year 100-Year

Physical ParametersTotal

Length(m)

Drainage AreaID

Total Area (ha) Command 85/10 Sw

(%)

Airport/Brasby Williams Tc (minutes)Weighted Runoff Coefficient

<=10-Year 25-Year

5-Year (mm/hr) 100-Year (mm/hr) 5-Year (mm/hr) 100-Year (mm/hr)5-Year 18 75.7 -- 61.9 --

100-Year 10 -- 178.6 -- 156.7

IDF Curve

A1 2.09 0.33 0.41 146 427A2 13.22 0.33 0.41 928 2,705A3 11.69 0.32 0.40 780 2,297A4 16.13 0.32 0.40 1,075 3,169A5 8.92 0.32 0.40 595 1,753A6 9.52 0.32 0.40 635 1,870

City of Ottawa IDF

POST-DEVELOPMENT RUNOFF COEFFICIENT CALCULATIONS

Drainage Area ID Drainage Area (ha)Weighted RO

Coeff. (C) 5-yrWeighted RO Coeff.

(C) 100-yr5-Year Flow Rate

(L/s)100-Year Flow Rate

(L/s)

TABLE A-5: PRE-DEVELOPMENT STORM SEWER DRAINAGE AREA AND FLOWS

STORM INFORMATION

Storm Time of concentration (min.)

City of Ottawa IDF MTO Extrapolation




Appendix B Post-development Stormwater Management Calculations

Soil Type: Soil Description HSG Land Use and Treatment: Condition Vegetation: Topography RC

Hard Surface Impervious Sandy, Sandy Loams and Gravels: Shallow, Overlying Percambrian bedrock or Clay Subsoil B Paved parking lots, roofs, driveways etc Paved or Roofs 0.90Woodland & Forest Sandy, Sandy Loams and Gravels: Shallow, Overlying Percambrian bedrock or Clay Subsoil B Woodlots and Forest Woodland: Rolling (5-10% Slope) 0.32

Open Space Sandy, Sandy Loams and Gravels: Shallow, Overlying Percambrian bedrock or Clay Subsoil B Open Space (Lawns, Golf Courses, Cemeteries, etc.): Fair (grass cover 50% to 75%) Pasture: Rolling (5-10% Slope) 0.29Gravel Sandy, Sandy Loams and Gravels: Shallow, Overlying Percambrian bedrock or Clay Subsoil B Gravel (including ROW) Gravel 0.40

TABLE B-1: POST-DEVELOPMENT SOIL AND RUNOFF COEFFICIENT DATA

Runoff CoefficientCurve NumberHydrologic Soils Group

User Input: Land Use Name

<= 10-Year25-Year Increase

(10%)

50-Year Increase

(20%)

100-Year Increase

(25%)<= 10-Year 25-Year 50-Year 100-Year

0.08 0.90 0.99 1.00 1.00

1.41 0.32 0.35 0.38 0.40

0.12 0.29 0.32 0.35 0.37

0.01 0.40 0.44 0.48 0.50

0.06 0.90 0.99 1.00 1.00

2.54 0.32 0.35 0.38 0.40

0.00 0.29 0.32 0.35 0.37

0.00 0.40 0.44 0.48 0.50

0.07 0.90 0.99 1.00 1.00

3.60 0.32 0.35 0.38 0.40

0.00 0.29 0.32 0.35 0.37

0.00 0.40 0.44 0.48 0.50

0.06 0.90 0.99 1.00 1.00

1.73 0.32 0.35 0.38 0.40

0.00 0.29 0.32 0.35 0.37

0.00 0.40 0.44 0.48 0.50

0.08 0.90 0.99 1.00 1.00

4.28 0.32 0.35 0.38 0.40

0.00 0.29 0.32 0.35 0.37

0.00 0.40 0.44 0.48 0.50

1.05 0.90 0.99 1.00 1.00

31.42 0.32 0.35 0.38 0.40

0.92 0.29 0.32 0.35 0.37

0.08 0.40 0.44 0.48 0.50

0.55 0.90 0.99 1.00 1.00

3.84 0.32 0.35 0.38 0.40

0.37 0.29 0.32 0.35 0.37

0.03 0.40 0.44 0.48 0.50

0.02 0.90 0.99 1.00 1.00

9.27 0.32 0.35 0.38 0.40

0.00 0.29 0.32 0.35 0.37

0.00 0.40 0.44 0.48 0.50


Gravel

0.32 0.35 0.38 0.40B8 9.29 NashHyd


TABLE B-2: POST-DEVELOPMENT DRAINAGE AREA PARAMETERS AND DATA


0.38 0.41 0.420.34

Land Use Area (ha)

Runoff Coefficient

B2 2.60 NashHyd


Drainage Area ID

Gravel


Land UseArea (ha) Command

B1 1.61 NashHydWoodland & Forest

Open Space


Gravel

0.36 0.39 0.410.33


Gravel

0.36 0.39 0.410.33


B4 1.79 NashHyd


B3 3.67 NashHyd

B5 4.36 NashHyd



Gravel

0.37 0.40 0.420.34


Gravel

0.36 0.39 0.410.33

B7 4.78 NashHyd


0.38 0.42 0.45 0.46Woodland & Forest

Open SpaceGravel

B6 33.47 NashHyd


0.33 0.37 0.40 0.41Woodland & Forest

Open SpaceGravel

Sw = 100 * (∆h - hf)0.75L - Lf

Where:Sw = watershed slope, %

∆h =

hf = sum of heights of rapids and waterfalls between 10% and 85% points, m.L = the total length of the main channel, includes the undefined flow path, to head of basin, m.Lf = the sum of lengths of rapids and waterfalls, up to 10% of L, m.

B1 NashHyd 194.08 156.37 37.71 8.11 264.07 4.682 15.31 HillyB2 NashHyd 178.85 155.90 22.95 0 170.47 0 17.95 HillyB3 NashHyd 177.38 156.52 20.86 0 250.63 0 11.10 HillyB4 NashHyd 167.39 152.30 15.09 0 177.98 0 11.30 HillyB5 NashHyd 174.50 148.11 26.39 0 195.94 0 17.96 HillyB6 NashHyd 205.11 171.68 33.43 0 656.40 0 6.79 RollingB7 NashHyd 189.12 179.22 9.90 0 313.89 0 4.21 FlatB8 NashHyd 191.39 158.38 33.01 0 479.66 0 9.18 Rolling

Total Height

Difference (m)

Drainage AreaID

Main Channel Length

(m)

Command Drainage Area Topography

85% Elevation

(m)

Waterfalls Length

10% Elevation

(m)

Waterfalls Height

Slope, Sw

(%)

TABLE B-3: POST-DEVELOPMENT WATERSHED SLOPE - 85/10 METHOD

difference in elevation, m, between the 85% point and the 10% point obtained from contours, airphotos, etc.

The Airport Formula The Bransby Williams Formula

tc = 3.26 (1.1-C) L0.5 tc = 0.057*LSw

0.33 (Sw0.2 * A 0.1)

where: tc = time of concentration, min. where tc = time of concentration, min.C = runoff coefficient C = runoff coefficientSw = watershed slope, % Sw = watershed slope, %L = watershed length, m. L = watershed length, m.

B1 1.61 NashHyd 0.34 0.38 0.41 0.42 15.31 264.07 16 16 8 8B2 2.60 NashHyd 0.33 0.36 0.39 0.41 17.95 170.47 13 12 12 5B3 3.67 NashHyd 0.33 0.36 0.39 0.41 11.10 250.63 18 17 17 8B4 1.79 NashHyd 0.34 0.37 0.40 0.42 11.30 177.98 15 14 6 6B5 4.36 NashHyd 0.33 0.36 0.39 0.41 17.96 195.94 14 13 12 5B6 33.47 NashHyd 0.33 0.37 0.40 0.41 6.79 656.40 34 32 31 18B7 4.78 NashHyd 0.38 0.42 0.45 0.46 4.21 313.89 26 11 11 11B8 9.29 NashHyd 0.32 0.35 0.38 0.40 9.18 479.66 27 26 25 24


<=10-Year

TABLE B-4: POST-DEVELOPMENT TIME OF CONCENTRATION

25-Year 50-Year 100-Year <=10-Year 25-Year 50-Year 100-Year

Physical ParametersTotal

Length(m)

Drainage AreaID

Total Area (ha) Command 85/10 Sw

(%)

Airport/Brasby Williams Tc (minutes)

5-Year (mm/hr) 100-Year (mm/hr) 5-Year (mm/hr) 100-Year (mm/hr)5-Year 16 79.6 -- 65.5 --

100-Year 10 -- 178.6 -- 156.7

IDF Curve

A1 1.61 0.34 0.42 122 337A2 2.60 0.33 0.41 189 527A3 3.67 0.33 0.41 266 741A4 1.79 0.34 0.42 133 370A5 4.36 0.33 0.41 315 880A6 33.47 0.33 0.41 2,477 6,883A7 4.78 0.38 0.46 405 1,102A8 9.29 0.32 0.40 654 1,833

City of Ottawa IDF

POST-DEVELOPMENT RUNOFF COEFFICIENT CALCULATIONS

Drainage Area ID Drainage Area (ha)Weighted RO

Coeff. (C) 5-yrWeighted RO Coeff.

(C) 100-yr5-Year Flow Rate

(L/s)100-Year Flow Rate

(L/s)

TABLE B-5: POST-DEVELOPMENT STORM SEWER DRAINAGE AREA AND FLOWS

STORM INFORMATION

Storm Time of concentration (min.)

City of Ottawa IDF MTO Extrapolation

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