draft drainage report - british columbia · design of highway culverts by the u.s. department of...

DRAFT DRAINAGE REPORT

BC HydroHighway No. 29 – Cache Creek East Embankment

July 24, 2019

Binnie File No. 15-0674

DRAINAGE REPORT

BC HYDRO HWY 29 CACHE CREEK EAST REALIGNMENT

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CONTENTS

1 INTRODUCTION ..................................................................................... 1

2 EXISTING DRAINAGE AND SITE CHARACTERISTICS ............................ 1

2.1 Sub-catchment G (407+740 to 409+000) ............................................................. 2

3 DESIGN CRITERIA ................................................................................... 2

3.1 Design Criteria References ....................................................................................... 2

3.2 Hydrologic Parameters .............................................................................................. 2

4 CLIMATE ................................................................................................. 3

4.1 Design Precipitation ................................................................................................... 3

5 STORMWATER CATCHMENT DESIGN FLOWS ...................................... 3

6 PROPOSED DRAINAGE INFRASTRUCTURE ........................................... 4

6.1 Culverts .......................................................................................................................... 4

6.2 Ditches ........................................................................................................................... 4

6.3 Existing Drainage Interaction ................................................................................54

6.4 Driveway Culverts .....................................................................................................65

6.5 Spillways ........................................................................................................................ 6

6.6 Scour Protection .......................................................................................................... 6

7 CLOSING ................................................................................................. 7

8 REFERENCES ........................................................................................... 8

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TABLESTable 2-1: List of Catchments and Existing Culverts ............................................................ 2

Table 5-1: Peak Design Flows ........................................................................................................ 3

Table 6-1: Culvert Sizing for Climate Change ......................................................................... 4

Table 6-2: Culvert Sizing for Historic Data ............................................................................... 4

FIGURESFigure 1-1: Project Location

Figure 6-1: Existing Ditch Profile

APPENDICESAppendix A: Drainage Catchment Map

Appendix B: Culvert Inspection Reports

Appendix C: Rainfall Intensity Curves

Appendix D: Design Calculations

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1 INTRODUCTION

This report deals specifically with the early works for the Cache Creek East section of Highway 29. A fulldescription of the Cache Creek East project can be found in the complete Cache Creek East drainagereport (Binnie 2019). The Cache Creek section lies approximately 25 kilometres west of Fort St. John.

Figure 1-1: Project Location

The purpose of this report is to review the existing drainage patterns, determine catchment areas,calculate design flows, and develop a drainage plan for the Cache Creek East Embankment. Thisdrainage analysis conforms to BC Supplement to TAC Geometric Design Guide – Section 1000 (BC TAC),and Technical Circular T-04/19: Resilient Infrastructure Engineering Design – Adaptation to the Impactsof Climate Change and Weather Extremes.

2 EXISTING DRAINAGE AND SITE CHARACTERISTICS

This project is located within an area of Highway 29 which has moderately dense forested side slopesand pasture or crop lands adjacent to the highway. The full Cache Creek watershed has been dividedinto 7 sub-catchments, labeled A through G, in accordance to these drainage pathways. The early worksonly encounter drainage from sub-catchment G. These sub-catchments can be seen in Figure 1 inAppendix A.

Sub-catchment G is comprised of milder sloped forest and crop land (~8%) in the upper reaches of thecatchment, followed by a steep sloped forested area (~38%) with several well-defined channels, andreturning to a moderately sloped crop land and pasture (~8%) along the exiting highway.

Sub-catchment G and its existing culverts are listed in Table 2-1 below.

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Table 2-1: List of Catchments and Existing Culverts

Catchment Name Catchment Area Existing Culverts

G 266.3 ha 1x900 mm, 2x600 mm

Culvert inspection reports for existing culverts can be found in Appendix B.

Subsurface conditions generally consist of a thin layer of topsoil underlain by layers of sand, sand andgravel, and gravel of variable thicknesses. The sand and gravel are underlain by shale bedrock (AMEC-Foster Wheeler, 2017). Sub-catchment G (407+740 to 409+000)

3 DESIGN CRITERIA

3.1 Design Criteria References

The following references were used to develop design criteria for the project:

§ B.C. Ministry of Transportation and Infrastructure Supplement to TAC Geometric DesignGuide (2019)

§ Technical Circular T04-19: Resilient Infrastructure Engineering Design – Adaptation to theImpacts of Climate change and Weather Extremes (2019)

§ Transportation Association of Canada (TAC) Geometric Design Guide (2019)

§ RTAC Drainage Manual (1982)

§ Hydraulic Design of Highway Culverts (Third Edition) – U.S. Department of Transportation(2012)

3.2 Hydrologic Parameters

The following hydrologic parameters have been used to estimate culvert design flow:

· Culverts less than 3 m span are designed to accommodate a 100-year + climate change returnperiod storm, with design flows calculated using the Rational Method.

o Culverts were analyzed and designed based on inlet flow control conditions andchecked for outlet control conditions using HY-8

o Culverts were analyzed and designed based on headwater to diameter ratio (HW/D) =1(maximum)

· Spillways are designed to meet maximum ponding requirements during a 5-year + climatechange return period storm.

· Temporary infrastructure is designed to accommodate a 20-year return period storm

· Design flows calculated using the Rational Method used the following coefficients:

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o Time of Concentration (tc) calculated using an average of the Hathaway formula, the BCMethod, and the SCS Curve Number Method

o Runoff Coefficient (C) = 0.25 to 0.40, based on RTAC Table 2.4.1 for forested andagricultural terrain. Runoff coefficient variance reflects differing slopes and soilconditions (i.e. gravel pits) in sub-catchment areas

o Manning’s roughness coefficient (r) = 0.40 to 0.70 for a mix of pasture and deciduoustimber (BC TAC section 1020.04)

o Curve Number (CN) = 40 for forest & 69 for rolling pasture / cropland from RTAC Table2.2.7

4 CLIMATE

A full climate change assessment is provided in the main Cache Creek East drainage report. An averageincrease in peak rainfall of 42.8% and 17.8% were used for the 100-year and 5-year storms, respectively,as per the IDF-CC Tool 3.0.

4.1 Design Precipitation

For Cache Creek, the IDF-CC Tool 3.0 was used with the Generalized Extreme Value (GEV) distributionoption to develop an IDF curve. IDF-Curve interpolation equations for climate change are provided bythe IDF-CC Tool 3.0 and can be found in Appendix C for reference.

For the 20-year design storm, an IDF curve was created using the GEV distribution and historic data fromFort St. John A. The IDF curve and associated interpolation equation can be found in Appendix C forreference.

5 STORMWATER CATCHMENT DESIGN FLOWS

Design flows for sub-catchment G were calculated for the proposed highway culverts. Peak flows werecalculated using the rational method for both 100-year and 20-year return period rainfall events. Table5-1 below summarizes the sub-catchment design flows:

Table 5-1: Peak Design Flows

CatchmentName

ReturnPeriod

CatchmentArea

Design Flow - No ClimateChange

Design Flow - ClimateChange

(ha) (m3/s) (m3/s)G 100-yr 266.3 3.33 4.76

G 20-yr 266.3 2.37 ---

The average increase in design flows due to climate change is approximately 42.8% for the 100-yearevent.

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6 PROPOSED DRAINAGE INFRASTRUCTURE

6.1 Culverts

No existing culverts intersect the highway along the proposed realignment; therefore, all culverts willneed to be new installations. Based on the projected 100-year design storm with climate change, 2 newculverts are proposed for sub-catchment G, of which only one is to be installed during the early works.Table 6-1 and Table 6-2 below list the stationing, flow, and recommended culvert sizes for both climatechange and historic data.

The proposed culverts were sized to convey 100-year + climate change peak flows while meeting theMoTI criteria of HW/D<1. Circular culverts were sized using inlet control equations from the HydraulicDesign of Highway Culverts by the U.S. Department of Transportation. A minimum diameter of 900 mmwas used for all highway cross culverts.

Table 6-1: Culvert Sizing for Climate Change

Catchment Name StationDesign Flow – Climate

ChangeRecommended Culvert

Sizing

(m3/s)

G407+9061 2.38 1400 mm 0.87

408+415 2.38 1400 mm 0.87

1Not included as part of early works

Table 6-2: Culvert Sizing for Historic Data

Catchment Name Station Design Flow – HistoricRecommended Culvert

Sizing

(m3/s)

G407+9061 1.67 1200 mm 0.89

408+415 1.67 1200 mm 0.89

1Not included as part of early works

6.2 Ditches

Special ditching will be used in sub-catchment G to redirect runoff from approximately Station 408+370,around the end of the early works embankment at approximately Station 407+920, and down to theexisting highway ditch. The special ditching can be found on Drawing R3-345-701 and Drawing R3-345-702.

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6.3 Existing Drainage Interaction

During early works, the existing highway will still be in use and therefore must be considered whenestablishing new drainage paths. Based on calculated design flows for the 100-year storm, the existinghighway cross-culverts are undersized.

Flow from sub-catchment G has been split between two proposed 1400 mm cross culverts to maintainflow distribution to the existing three downstream highway cross-culverts (1x900 mm, 2x600 mm).

Due to the temporary nature of some early works components (such as access roads), the 20-year designstorm was assessed to ensure temporary driveway culverts are adequate. The existing highway crossculverts were also evaluated to assess performance during the 20-year design storm.

Flow during the 20-year return design storm will pass through the new 1400 mm culvert and then travelalong the existing highway ditch to two existing 600 mm diameter CSP culverts. Excess runoff thatbypasses the existing 600 mm culverts will flow along the existing highway ditch passing throughproposed twin 400 mm temporary access road culverts before reaching the existing 900 mm crossculvert.

During the 20-year return period historic precipitation event, 1.2 m3/s is expected to flow through theproposed 1400 mm culvert and along the ditch. The existing 600 mm culverts are installedapproximately 0.85 m and 0.65 m below the invert of the existing highway ditch as circled in red onFigure 6-1, so they are likely to surcharge during significant events. Based on the existing ditch crosssections, the first 600 mm culvert is expected to surcharge to a depth of approximately 1.00 m, at whichdepth approximately 0.55 m3/s of water can flow through the culvert. The second 600 mm culvert isexpected to surcharge to a depth of approximately 0.79 m, at which depth approximately 0.45 m3/s ofwater can flow through the culvert.

Figure 6-1: Existing Ditch Profile

The remaining water that will travel further downstream along the existing highway ditch and throughthe access road twin 400 mm culverts is approximately 0.20 m3/s. Due to site constraints, the largestpipe that can fit under the access road is 400 mm in diameter with a longitudinal slope of 0.5%. Withtwinned 400 mm culverts, this would result in outlet-controlled flow with a HW/D of approximately 1.05(total water depth at inlet of 0.42 m).

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Downstream of the twinned 400 mm culverts, the existing 900 mm diameter culvert will receive theremaining 0.20 m3/s of flow, as well as the second half of the flow from Catchment G, for a total flow of1.39 m3/s. For this flow to travel through the 900 mm culvert, the resulting HW/D would beapproximately 1.55 or a total depth of 1.395 m at the inlet of the culvert. Based on survey and LiDAR ofthe existing highway, there is an available 1.44 m of depth before roadway overtopping would occur.Due to the minimum freeboard at this location during the expected 20-year return period storm andtaking into consideration margins of error for design flow calculations, it is likely that this culvert willovertop during the 20-year storm. There is also evidence of recent overtopping as discussed in theculvert inspection report (Appendix B).

6.4 Driveway Culverts

Two driveway culverts are to be installed as part of temporary access roads. Due to their temporarynature, these culverts will be sized based on the 20-year return period design flow, not including climatechange.

Culvert locations can be found on Drawing R3-345-701 and Drawing R3-345-702. The culvert atStation 510+060.995 is a 600 mm diameter CSP culvert that receives water from a small section of theadjacent field (<1.0 ha). The culvert at Station 500+247.500 is a twinned 400 mm diameter CSP culvertwhich receives the bypass flow from the two existing 600 mm highway cross culverts.

6.5 Spillways

As part of the early works, the final road surface is not being constructed. As per the BC Supplement toTAC requirements, the final road surface will require spillways. Riprap outfalls will be constructed at thelocations of spillways from the final design. These outfalls will tie into the spillways once they areconstructed. The following design criteria is used for spillways.

§ Maximum 1.2 m ponding width during a 5-year return rainfall event

Spillways are required typically every 100 m. Spillway locations can be found on Drawing R3-345-701and Drawing R-3-345-702. A small v-notch swale with 2:1 side-slopes and a 0.3 m depth is providedalong the early work embankment to convey water to spillway locations. A typical section can be foundon Drawing R3-345-301.

6.6 Scour Protection

To protect against scour, all culverts will include, as a minimum, standard 25 KG riprap aprons. Theculvert at Station 408+415 will use a 250 KG riprap apron. Calculations for scour can be found inAppendix D. 10 KG riprap spillways will be used to protect fill slopes from pavement drainage.

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7 CLOSING

We trust you find the above suitable for your needs. Should you have any questions or comments onthe information contained herein, please do not hesitate to contact the undersigned or the ProjectManager.

Prepared by: Reviewed by:

Cyrus Lau, E.I.T.Water Resources Engineer

Amanda Rust, P. Eng.Senior Water Resources Engineer

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8 REFERENCES

Amec Foster Wheeler Ltd. (2016). Site C Clean Energy Project - Engineering Design Service for Highway 29Road and Infrastructure - Environmental Protection Plan. Amec Foster Wheeler Ltd.

American Iron and Steel Institute. (2007). Handbook of Steel Drainage & Highway Construction Products.Cambridge: Corrugated Steel Pipe Institute.

British Columbia Ministry of Transportation. (2007). Supplement to TAC Geometric Design Guide. Victoria.

British Columbia Ministry of Transportation and Infrastructure. (2016). Climate Change and ExtremeWeather Event Preparedness and Resilience in Engineering Infrastructure Design. Victoria.

Federal Highway Administration. (2006). Hydraulic Design of Energy Dissipators for Culverts and Channels.Denver: U.S. Department of Transportation.

Government of Canada. (2018, July 31). Canadian Climate Normals. Retrieved from Canadian ClimateNormals - Climate - Environment and Climate Change Canada:http://climate.weather.gc.ca/climate_normals/

Ministry of Forests, Lands and Natural Resource Operations. (2012). Fish-stream Crossing Guidebook.Victoria: Ministry of Environment.

Ministry of Transportation and Infrastructure. (2016). 2016 Standard Specifications for HighwayConstruction. Victoria.

R.F. Binnie & Associates Ltd. (2019). Highway No. 29 - Cache Creek East Realignment 100% FunctionalDesign. Burnaby.

Roads and Transportation Association of Canada. (1982). Drainage Manual. Ottawa.

U.S. Department of Transportation. (2012). Hydraulic Design of Highway Culverts. Washington, D.C.:Federal Highway Administration.

University of Victoria. (2013). PLAN2ADAPT. Retrieved October 15, 2018, from Pacific Climate ImpactsConsortium: https://www.pacificclimate.org/analysis-tools/plan2adapt

Western University. (2018). IDF_CC Tool 3.0. Retrieved October 15, 2018, from Computerized Tool for theDevelopment of Intensity-Duration-Frequency Curves under Climate Change - Version 3.0:http://www.idf-cc-uwo.ca/

APPENDIX ADRAINAGE CATCHMENT MAP

APPENDIX BCULVERT INSPECTION REPORTS

Project #: Type/Class: Rise: Span: Skew:

Highway: Material: Approx Cover (US/DS):

Culvert: Barrel Shape: Est. Present Water Level Depth (m):

Appurtenances (circle one):Upstream: Projecting / Mitered / Headwall / Headwall & Wingwalls / Flared End Section / _____________________Downstream: Projecting / Mitered / Headwall / Headwall & Wingwalls / Flared End Section / _____________________

UTM Zone: UTM East: UTM North:

Inspector: Company Name: Inspection Date: Time:

Rating Comments Visual Rating Scale

Top ______________________________________________________________________90 - Galvanizing intact

Sides ______________________________________________________________________75 - Galvanizing partly gone, some rust

Invert ______________________________________________________________________50 - Galvanizing gone, significant metal loss

Pipe Exterior ______________________________________________________________________25 - Deep pitting, heavy metal loss, metal perforated

Condition of 0 - Metal perforatedCoating: ______________________________________________________________________

Paving: ______________________________________________________________________

Water pH: _____________________________________________ Water Resistivity: _____________________________________

Soil Classifications: ______________________________________ Original Pipe Thickness: ________________________________

Debris/Veg Blockage at inlet or outlet ______________________________________________________________________

Sediment Blockage at inlet/outlet ______________________________________________________________________

Buoyancy or Crushing-Related Inlet Failure ______________________________________________________________________

Poor Channel Alignment ______________________________________________________________________

Previous and/or Frequent Overtopping ______________________________________________________________________

Local Outlet Scour ______________________________________________________________________

Embankment Piping ______________________________________________________________________

Channel Degradation / Headcut ______________________________________________________________________

Embankment Slope Instability ______________________________________________________________________

No Access / Ends Totally Buried / Submerged ______________________________________________________________________

Exposed Footing (Open-Bottom Culvert Only) ______________________________________________________________________

Photo # Photo View Description Photo # Photo View Description

1 4

2 5

3 6

Field Measurements

Visual Evaluation

Culvert Inspection Sheet

Performance Problems

Photo Log

15-0674

#29

C1

Highway Cross-Culvert

CSP

Circular

900 mm 900 mm

2.5 m

10 609860 6237881

Stephen Ducey Binnie July 5, 2019 8:45 a.m.

90 - appears in very good condition




Inlet/Outlet clear

Some sediment visible in pipe inlet

No inlet failure observed

Outlet aligned well, inlet shows distinct scoured channel path

Evidence of highway overtopping visible (sediment across entire highway)

Outlet is cantilevered, roadside barrier pieces in outlet channel, evidence of scour along sides of channel

No evidence of piping

Scoured inlet channel distinctly visible

No evidence of embankment slope instability

Access to both inlet and outlet availble

N/A

C1-1

C1-2

C1-3

Inlet location/side view

Inlet front view

Inlet invert

C1-4

C1-5

C1-6

Outlet top view

Outlet side view

Overtopped channel













Paving: ______________________________________________________________________















1 4

2 5

3 6

Field Measurements

Visual Evaluation



Photo Log

15-0674

#29

C2


CSP

Circular

600 mm 600 mm

1 m

10 610179 6237939


75 - Visible rust on top of culvert

80 - Some rust on one half of culvert sides

65 - Rust apparent, sedimentation and potential metal loss

75 - Rust visible on culvert exterior

Lots of thick vegetation at inlet, outlet buried

Very light sediment visible in culvert inlet

Inlet appears to have some dents

No apparent poor channel alignment

Scour along embankment shows evidence of overtopping

N/A - Outlet buried

No evidence of piping

No evidence of channel degradation

Scour from overtopping shows some embankment fill material washed away

Outlet buried

N/A

C2-1

C2-2

C2-3

Culvert inlet location

Culvert inlet

Culvert inlet invert

C2-4

C2-5

Buried outlet top view

Buried outlet side view













Paving: ______________________________________________________________________















1 4

2 5

3 6

Field Measurements

Visual Evaluation



Photo Log

15-0674

#29

C3


CSP

Circular

600 mm 600 mm

1 m

10 610317 6237989


No view provided

90 - apparently in good condition from available photos

0 - Metal perforated

No view provided

Tall grass vegetation surrounding inlet

No outlet blockage

Inlet not properly visible from photos

No evidence of poor channel alignment

Evidence of surcharge up to roadside

Distinct outlet flow path, appears to continue through half-pipe flume

No embankment piping visible

No clear channel degradation observed

Inlet embankment shows some scour eating away at embankment fill

Ends covered with thick tall grass vegetation

N/A

C3-1

C3-2

C3-3

Culvert inlet location

Culvert inlet invert

Culvert inlet scour/overtopping

C3-4

C3-5

C3-6

Culvert outlet location

Culvert outlet

Culvert outlet invert

APPENDIX CRAINFALL INTENSITY CURVES

Figure B-1: Cache Creek Historic IDF Curves

Figure B-2: Cache Creek Historic IDF Curve Interpolation Equations

Figure B-3: Cache Creek Climate Change IDF Curves

Figure B-4: Cache Creek Climate Change IDF Curve Interpolation Equations

APPENDIX DDESIGN CALCULATIONS

Equations & Charts:

IDF rainfall intensity: = ∗ ( + )

Hathaway Formula: = ( ∗ ) .

. ∗ .

SCS Curve: = 1.7 ∗ ((1000 ∗ ) . ) ∗. ∗ ∗

.

∗(( ∗ ) . )

Rational Method: =

BC Method:

Design Flow Calculation C = Average run off coefficient = Inputr = Roughness coefficient = CalculatedTc = Time of concentration RAINFALL DATA: Cache Creek (Lat: 46.27081, Lon:-121.24065)I = Rainfall intensityQp = Peak flow Flat = 0%

Rolling = 1% Return Period IDF-CC A B t0Map Version/Date: 11/5/2018 Moderate = 2.5% Climate Change 100 47.4 -0.754 0.041Climate Change Steep = 10% Historic 100 33.2 -0.754 0.041

L (km) AB Sqrt(Area) S (m/m)

MainChannel (ha) (km) Main Channel

Ave Slope C r CN HathawayFormula

BC Method(Figure1020.B)

SCS CurveNumberMethod

Average HathawayFormula BC Method




Average

B 0.59 12.7 0.36 3% 0.35 0.5 69.0 0.78 0.77 0.73 0.76 54.94 55.51 57.82 56.09 0.68 0.69 0.71 0.70D 0.28 7.5 0.27 4% 0.35 0.5 69.0 0.51 0.35 0.33 0.40 74.61 96.22 99.36 90.06 0.54 0.70 0.72 0.71E 0.24 12.7 0.36 6% 0.35 0.5 69.0 0.44 0.45 0.25 0.38 82.43 81.04 119.28 94.25 1.02 1.00 1.47 1.24

SteepA 0.75 39.3 0.63 14% 0.40 0.7 40.0 0.71 0.77 0.84 0.77 59.02 55.51 52.01 55.51 2.58 2.42 2.27C 0.57 10.1 0.32 22% 0.40 0.7 40.0 0.56 0.43 0.54 0.51 69.61 83.62 71.27 74.83 0.78 0.94 0.80F 0.64 45.0 0.67 16% 0.40 0.7 40.0 0.64 0.80 0.70 0.72 63.31 54.01 59.13 58.82 3.17 2.70 2.96G 0.38 14.6 0.38 25% 0.40 0.7 40.0 0.45 0.50 0.37 0.44 80.83 75.33 92.52 82.89 1.31 1.22 1.50

FlatA 1.45 84.1 0.92 3% 0.32 0.4 60.3 1.06 1.55 1.82 1.48 44.13 33.40 29.66 35.73 3.30 2.50 2.22C 0.94 26.5 0.51 3% 0.33 0.4 63.2 0.88 1.05 1.25 1.06 50.29 44.39 39.07 44.58 1.22 1.08 0.95F 2.99 154.1 1.24 7% 0.31 0.7 57.4 1.60 1.80 2.36 1.92 32.60 29.92 24.53 29.01 4.33 3.97 3.25G 2.97 251.7 1.59 8% 0.29 0.7 51.6 1.53 2.20 2.48 2.07 33.68 25.80 23.60 27.69 6.83 5.23 4.78

CombinedA 2.20 123.4 0.35 1.77 2.32 2.66 2.25 30.35 24.80 22.38 25.84 3.59 2.94 2.65 2.79C 1.38 36.6 0.35 1.44 1.48 1.79 1.57 35.19 34.55 30.01 33.25 1.25 1.23 1.07 1.15F 3.60 199.1 0.33 2.24 2.60 3.06 2.63 25.44 22.79 20.19 22.81 4.65 4.16 3.69 3.93G 3.35 266.3 0.30 1.98 2.70 2.85 2.51 27.84 22.16 21.28 23.76 6.10 4.85 4.66 4.76

No Climate ChangeL (km) AB Sqrt(Area) S (m/m)

MainChannel (ha) (km) Main Channel

Ave Slope C r CN HathawayFormula

BC Method(Figure1020.B)






Average

B 0.59 12.7 0.36 3% 0.35 0.5 69.0 0.78 0.77 0.73 0.76 38.48 38.88 40.50 39.29 0.48 0.48 0.50 0.49D 0.28 7.5 0.27 4% 0.35 0.5 69.0 0.51 0.35 0.33 0.40 52.26 67.40 69.59 63.08 0.38 0.49 0.51 0.50E 0.24 12.7 0.36 6% 0.35 0.5 69.0 0.44 0.45 0.25 0.38 57.73 56.76 83.55 66.01 0.71 0.70 1.03 0.87

SteepA 0.75 39.3 0.63 14% 0.40 0.7 40.0 0.71 0.77 0.84 0.77 41.34 38.88 36.43 38.88 1.81 1.70 1.59C 0.57 10.1 0.32 22% 0.40 0.7 40.0 0.56 0.43 0.54 0.51 48.76 58.57 49.92 52.41 0.55 0.66 0.56F 0.64 45.0 0.67 16% 0.40 0.7 40.0 0.64 0.80 0.70 0.72 44.35 37.83 41.42 41.20 2.22 1.89 2.07G 0.38 14.6 0.38 25% 0.40 0.7 40.0 0.45 0.50 0.37 0.44 56.62 52.76 64.81 58.06 0.92 0.86 1.05

FlatA 1.45 84.1 0.92 3% 0.32 0.4 60.3 1.06 1.55 1.82 1.48 30.91 23.39 20.77 25.02 2.31 1.75 1.55C 0.94 26.5 0.51 3% 0.33 0.4 63.2 0.88 1.05 1.25 1.06 35.23 31.09 27.37 31.23 0.86 0.76 0.66F 2.99 154.1 1.24 7% 0.31 0.7 57.4 1.60 1.80 2.36 1.92 22.83 20.95 17.18 20.32 3.03 2.78 2.28G 2.97 251.7 1.59 8% 0.29 0.7 51.6 1.53 2.20 2.48 2.07 23.59 18.07 16.53 19.39 4.78 3.66 3.35

CombinedA 2.20 123.4 0.35 1.77 2.32 2.66 2.25 21.26 17.37 15.68 18.10 2.52 2.06 1.86 1.96C 1.38 36.6 0.35 1.44 1.48 1.79 1.57 24.65 24.20 21.02 23.29 0.88 0.86 0.75 0.80F 3.60 199.1 0.33 2.24 2.60 3.06 2.63 17.82 15.96 14.14 15.97 3.25 2.92 2.58 2.75G 3.35 266.3 0.30 1.98 2.70 2.85 2.51 19.50 15.52 14.90 16.64 4.27 3.40 3.26 3.33

Notes: C = Runoff coefficient set to based on hybrid forest and pasture RTAC 2.4.1r = roughness coefficent from BC TAC Page 1020-4CN = Curve Number from RTAC Table 2.2.7 (Type B soils for meadow/woods )

Catchment Area Land Charactristics Tc (hr) I (mm/hr) Qp (m3/s) (Rational Method)

Catchment Area Land Charactristics Tc (hr) I (mm/hr) Qp (m3/s) (Rational Method)

Hwy 29 - Cache Creek Design Flows

Table 4 - RIPRAP FOR CULVERT OUTLETS

UpdateManning's Flow 408+415 500+247.500 510+060.995 Units

Length = mInlet Elev = m

Outlet Elev = mDepth of Flow = 0.70 0.40 0.13 mArea of Flow = 0.770 0.126 0.045 cu.m

Angle (water) = 1.571 3.142 0.968 radiansWetted Perimeter = 2.199 1.257 0.581 m

Top width of water = 1.400 0.000 0.494 mCulvert Diameter = 1.40 0.40 0.60 m

Hydraulic Radius, Rh = 0.350 0.100 0.078 mDitch Discharge, Q = 2.36 0.09 0.10 cu.m/s

1:100 year Design Flow = 2.38 0.10 0.10 cu.m/sAvg. Channel Velocity, V = 3.07 0.69 2.28 m/s

Channel Slope, S = 1.86% 0.50% 7.69% m/mMannings Coefficient = 0.022 0.022 0.022

Equivalent Depth = 0.62 0.25 0.15 mFroude Number = 1.2 0.4 1.9

HEC 14 - Rip Rap ApronTailwater = 0.70 0.40 0.24

(Use if supercritical)D' = 1.05 0.40 0.37D50 = 0.18 0.01 0.03

Min 25KG Class (KG) = Class 10kg Class 10kg Class 10kg

Culvert Location

Ditch Capacity using Mannings

Mannings equation: Q=(1/n)*AR^0.67*√S

Update

Manning'sSpecial Ditching (west end,100-yr + CC)

Special Ditching (east end, 100-yr+ CC) Swale Existing Highway Ditch (20yr)

Existing Highway Ditch (20yr -after first 600mm)

Existing Highway Ditch (20yr -after 2nd 600 mm)

Depth of Flow = 0.440 0.700 0.300 0.170 0.195 0.140Area of Flow = 1.021 2.170 0.180 1.301 0.665 0.441

Slope of left bank (z:1) = 3.000 3.000 2.000 15.000 15.000 15.000Slope of right bank (z:1) = 3.000 3.000 2.000 75.000 20.000 30.000

Wetted Perimeter = 3.783 5.427 1.342 15.307 6.836 6.307Top width of water = 3.640 5.200 1.200 15.300 6.825 6.300

Bottom width of water = 1.000 1.000 0.000 0.000 0.000 0.000Hydraulic Radius, Rh = 0.270 0.400 0.134 0.085 0.097 0.070

Catchment area =Ditch Capacity (max slope), Q = 2.37 2.38 0.60 1.20 0.67 0.19

1:100 year Design Flow = 2.38 2.38 0.02 1.19 0.65 0.20Avg. Channel Velocity, V = 2.32 1.10 3.35 0.92 1.01 0.43Channel Slope (max), S = 5.00% 0.66% 8.00% 2.09% 2.09% 0.59%

Mannings Coefficient for TRM = 0.040 0.040 0.022 0.030 0.030 0.030 Trial size d50 = --- 260.000

Calculated d50 0.158 0.022Class size of rip rap Class 10kg Class 10kgCHECK Froude Number < 1 1.1 0.4

*First culvert approx 0.8 m below ground*Second culvert approx 0.65 m below ground

Ditch Capacity using Blodgett and bathurstEquations from HEC15

Mannings equation 6.1:n = 0.319*da^(1/6) (2.25+5.23log(da/d50)) Equation 6.2

n = da^(1/6)√g*f(Fr)*f(REG)*fCG)

only valid where 1.5<da/d50<185 where f(Fr)= (0.28*Fr/b)^(log(0.755/b))f(REG) = 13.434*(T/D50)^0.492*b^(1.025*(T/D50)^0.118)f(CG) = (T/da)^-bT= Channel top width (m)b = effective roughness concentration = 1.14*(D50/T)^0.453*(da/D50)^0.814

**MILD < 5%, STEEP > 10%, IN BETWEEN = LARGER OF MILD/STEEP METHOD only valid where 0.3<da/d50<1.5

Station = 407+906 408+415 Ditch to 408+415 Ditch after 408+415Depth of Flow = 0.530 0.530 0.575 0.215

Average Depth of Flow = 0.313 0.313 0.352 0.165Area of Flow = 2.427 2.427 1.567 0.615

Slope of left bank (1:z) = 6.000 6.000 3.000 4.000Slope of right bank (1:z) = 6.000 6.000 3.000 4.000

Wetted Perimeter = 7.848 7.848 4.637 3.773Top width of water, T = 7.760 7.760 4.450 3.720

Bottom width of water = 1.400 1.400 1.000 2.000Hydraulic Radius, Rh = 0.309 0.309 0.338 0.163

Avg. Channel Velocity, V = 0.926 0.926 1.137 3.644Channel Slope (max), S = 4.00% 4.00% 4.60% 33.00%Mannings Coefficient, n =eqn 6.1 0.098 0.098 0.091 -0.436Mannings Coefficient, n =eqn 6.2 0.093 0.093 0.068 0.047

Eq. 5.7.2.1-1, n 0.038 0.038 0.038 0.044Froude Number = 0.4 0.4 0.5 2.5

f(Fr) = 0.678 0.678 0.741 2.359b = 0.285 0.285 0.403 0.178

f(REG) = 10.437 10.437 14.775 3.739f(CG) = 0.401 0.401 0.360 0.574

Ditch Capacity, Q = 2.39 2.39 2.38 2.391:25 year Design Flow = 2.38 2.38 2.38 2.38

Trial size d50 (m) = 0.260 0.260 0.260 0.565Calculated d50 0.180 0.180 0.204 0.542Class size of rip rap Class 10kg Class 10kg Class 25kg Class 250kgCHECK Froude Number < 1 0.4 0.4 0.5 2.5CHECK 1.5<da/d50<185 Method not valid- use equation 6.2 Method not valid- use equation 6.2Method not valid- use equation 6.2Method not valid- use equation 6.2CHECK 0.3<da/d50<1.5 equation 6.2 = OKAY equation 6.2 = OKAY equation 6.2 = OKAY Method not valid

Use Eq. 5.7.2.1-1-HEC 15 results Class 25kg Class 25kg Class 25kg Class 250kgHEC 23 results Class 10kg Class 10kg Class 10kg Class 250kgUSACE Results Class 10kg Class 10kg Class 10kg Class 250kg

draft drainage report - british columbia · design of highway culverts by the u.s. department of...

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