Design Report for the Athabasca River Erosion Control Project

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DISCLAIMER

This document entitled Design of Athabasca River Erosion Control Protection Works at

Whitecourt, Alberta " was prepared by Stantec Consulting Ltd. for the Town of Whitecourt and

Woodlands County. This report was prepared to response to comments received during the

meeting with Alberta Environment and Sustainable Resource Development (ESRD) on January 28,

2015 in Spruce Grove, AB.

The material in this report reflects Stantec Consulting Ltd's best judgment in light of the

information available to it at the time of preparation. Any use which a third party makes of this

report, or reliance on or decisions made based on it, are the responsibilities of such third parties.

Stantec Consulting Ltd. accepts no responsibility for damages, if any, suffered by any third party

as a result of decisions made or actions based on this report.

Prepared by: Reviewed by:

Arshed Mahmood, M.Sc., P.Eng. Ralph Walters, M.Eng., P.Eng.

Bridge Planning and River Engineer Senior Bridge Planning and River Engineering

Specialist

Design of Athabasca River Erosion

Control Protection Works at

Whitecourt, Alberta Town of Whitecourt Woodlands County Box 509 P.O. Box 60 5004 52nd Avenue #1 Woodlands Lane Whitecourt, Alberta Whitecourt, Alberta T7S 1N6 T7S 1N3 March 27, 2015

Design of Athabasca River

Erosion Control Protection

Works at Whitecourt, Alberta

Prepared for:

Town of Whitecourt

Box 509

5004 52nd Avenue

Whitecourt, Alberta T7S 1N6

and

Woodlands County

P.O. Box 60

#1 Woodlands Lane

Whitecourt, Alberta T7S 1N3

Prepared by:

Stantec Consulting Ltd.

Project No. 113530338

March 27, 2015

DESIGN OF ATHABASCA RIVER EROSION CONTROL PROTECTION WORKS AT WHITECOURT, ALBERTA

Table of Contents

1.0 PROJECT BACKGROUND ............................................................................................. 1.1

2.0 HYDROTECHNICAL SUMMARY ..................................................................................... 2.1

2.1 HEC-RAS MODELING ....................................................................................................... 2.4 2.1.1 HEC-RAS Model .............................................................................................. 2.5 2.1.2 Model Input Data .......................................................................................... 2.5 2.1.3 Modeling Results ............................................................................................ 2.6

2.1.3.1 Hydraulic Impact on Hwy 43 Bridge ........................................................... 2.6 2.1.3.2 Hydraulic Impact on Pembina Pipeline Crossing Downstream of

Study Reach ................................................................................................... 2.7 2.1.3.3 Hydraulic Impact on Athabasca River Left (North) Bank ...................... 2.12 2.1.3.4 Spurs Hydraulic Impact on Erosion of Athabasca River (River

Banks, Mid-Channel Bars and Streambed) .............................................. 2.15 2.1.3.5 Installation of 3.0 m Diameter CSP Pipe under Spur #10 for Fish

Connectivity and Pipe Maintenance ....................................................... 2.28 2.1.3.6 Spurs Hydraulic Impact on McLeod River and Athabasca River

Ice Jams ........................................................................................................ 2.30 2.1.3.7 Hydraulic Impact (Raise in Design Water Level Elevation) on River

in Study Reach ............................................................................................. 2.34

3.0 ALTERNATIVE RIVER BANK PROTECTION WORKS OPTIONS ....................................... 3.35

3.1 DO NOTHING OPTION ................................................................................................... 3.35

3.2 ADVANTAGES OF LONG SPURS VS ROCK RIPRAP BANK PROTECTION WORKS ..... 3.35

3.3 OPINION OF PROBABLE COST ESTIMATE OF LONG SPURS VS ROCK RIPRAP

BANK PROTECTION WORKS........................................................................................... 3.36

4.0 GEOTECHNICAL INVESTIGATION .............................................................................. 4.40

4.1 DESIGN SCOUR DEPTH ................................................................................................... 4.40

5.0 ENVIRONMENTAL ASSESSMENT AND REGULATORY APPROVALS ............................. 5.41

6.0 CONCLUSIONS AND RECOMMENDATIONS .............................................................. 6.41

7.0 CLOSING .................................................................................................................... 7.44

LIST OF APPENDICES

APPENDIX A Stantec Responses to ESRD Comments

APPENDIX B Design Drawings Issued for Environmental Approvals

APPENDIX C Sketches

APPENDIX D HEC-RAS Results

APPENDIX E Geotechnical Information

APPENDIX F Town of Whitecourt Letter to ESRD Dated March 03, 2015


Project background

March 27, 2015

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1.0 PROJECT BACKGROUND

The detail of project background information is available in Stantec Consulting Ltd. (Stantec)

July 2013 report Whitecourt River Engineering Study and Conceptual Design of River Bank

Protection Works of the Athabasca River from Whitecourt River Boat Park to the Pipelines East of

the Golf Course prepared for Town of Whitecourt, Woodlands County and Millar Western Forest

Products Ltd.

The Athabasca River is a highly mobile bed river and is actively readjusting its channels and

banks. This mobility and constantly adjusting of its banks is a result of the steep river slope, the

river bed material along with the forming of gravel bars in the rivers channel. The annual minor

and major floods events are causing the river to shift its main and secondary channels resulting

in major lateral bank erosion, especially on its right (south) bank. It has removed much of the

vegetated buffer zone area next to the river making the banks susceptible to increased lateral

erosion at several critical areas. High flows during the summer of 2012 resulted in excessive

erosion of the right (south) bank of the Athabasca River at Whitecourt downstream from the

Highway #43 bridge to a major pipeline crossing 3.5km east.

Stantec recommends a series of spurs be placed in the river to deflect the flow away from the

river right (south) bank, starting at River Boat Park and ending at the pipeline crossing east of the

golf course.

This project is for the construction of 14 new spurs and one existing spur to be reinforced with

Class 3 rock (max size of rock 1.1 m) as well as several mini spurs. 14 of the 15 spurs will be

armored with Class 3 rock riprap. The spurs are being constructed to prevent the Athabasca

River from migrating further to the south along this reach and putting land, properties and utilities

at risk.

2.0 HYDROTECHNICAL SUMMARY

The Water Survey of Canada (WSC) maintains stream flow gauges on both the Athabasca River

and McLeod River in the vicinity of the Town of Whitecourt. Athabasca River near Windfall,

gauge 07AE001, has data records for the period of 1960 to 2012. This gauge is located some 32.0

km upstream of Athabasca/McLeod confluence. The McLeod River gauge 07AG004 is located

approximately 29.0 km upstream of the Athabasca/McLeod Rivers confluence and it has data

records for the period of 1968 to 2012. Figure 1 shows the approximate location of gauges

07AE001 and 07AG004 in respect to the project location. A review of WSC data indicates that all

high flows in the Athabasca River since 1960 near Windfall has occurred in May to September. A

review of WSC data indicates that all high flows in the McLeod River since 1960 near Whitecourt

have occurred in April to September. Ice jam events occurred in April during breakup.


Hydrotechnical Summary

March 27, 2015


Figure 1 Approximate location of Athabasca River near Windfall (Gauge 07AE001) and McLeod River near

Whitecourt (Gauge 07AG004) in respect to project location.

WSC Gauge

07AG004

Project

Location

WSC Gauge

07AE001



March 27, 2015


Table 1 shows that daily average flows are highest from May to August for the Athabasca River

near Windfall, gauge 07AE001. Lower daily average flows are observed from January to April

and September to December. This suggests a preferred in stream construction in Athabasca

River upstream of its confluence with McLeod River from September to November.

Table 1 Mean, Maximum and Minimum Daily Average Flows for the Athabasca River

near Windfall, Gauge 07AE001

Daily Flow

(m3/s) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Mean

Mean 53.7 50.2 49.5 100 289 634 621 436 277 172 93.6 65.1 253

Max 102 65.3 88.3 171 534 1030 1090 690 484 301 151 136 357

Min 36.4 35.7 28.1 45.5 162 404 378 267 155 95.8 56.2 40.9 185

Table 2 shows that daily average flows are highest from May to August for the McLeod River

near Whitecourt, gauge 07AG004. Lower daily average flows are observed from January to

April and September to December. This suggests a preferred in stream construction in

Athabasca River downstream of its confluence with the McLeod River from September to

November.

Table 2 Mean, Maximum and Minimum Daily Average Flows for the McLeod River near

Whitecourt, Gauge 07AG004

Daily Flow

(m3/s) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Mean

Mean 5.45 4.09 9.49 49.2 99.4 115 107 59.1 42.1 31.9 14.7 10.2 51.1

Max 6.55 5.87 35.8 107 246 443 313 254 136 105 17.4 10.9 51.1

Min 4.35 2.30 2.83 18.9 25.9 26.9 21.9 10.7 9.69 9.61 11.9 9.54 51.1

The Restricted Activity Period (RAP) for the Athabasca River upstream of its confluence with

McLeod River is September 01 to July 15th and September 1 to June 30th downstream of the

confluence. Due to the large extent of the project and the nature of the work, the construction

of spurs in the least sensitive river habitats may have to occur within the RAP. Instream works,

including the placement of rock and fill for the spurs, would be preferred to occur from

September 01 to November 30.

The flood frequency estimate for return periods ranging from 2 years to 1000 years provided by

Northwest Hydraulic Consultants Ltd. (Woodlands County Public Information Session Athabasca

and McLeod Rivers Flood Hazard Identification Study June 10, 2014 7:00 P.M.) is included in

Table 3. 1:100 year flood is design flood for this project. A hard copy of this report was provided



March 27, 2015


by Town of Whitecourt to Stantec. Right/left banks are a river engineering terminology that

describes the river banks relative to an observer looking downstream in which the right bank is to

the observers right, and vice versa.

Table 3 Open Water Flood Frequencies, McLeod River and Athabasca River near

Whitecourt

Return Period

(Years)

Athabasca River

(Downstream of Confluence)

(m3/s)

Athabasca River

(Upstream of Confluence)

(m3/s)

McLeod River

(m3/s)

2 1521 1104 468

5 2182 1441 810

10 2684 1676 1098

20 3217 1911 1424

50 3988 2230 1928

100 4634 2482 2374

200 5341 2746 2884

500 6384 3116 3671

1000 7265 3413 4364

2.1 HEC-RAS MODELING

This section provides a summary for the Athabasca River Modeling using HEC- RAS River Analysis

System to evaluate the hydraulic impact of proposed river bank protection works in study area

for 1:100 year design flood and floods with several return periods. The HEC-RAS model we

developed was based on Northwest Hydraulic Consultants Ltd. Woodlands County Flood Hazard

Identification Study Athabasca and McLeod Rivers at Whitecourt dated March 07, 2013.

Stantec would like to extend special thanks to Northwest Hydraulic Consultants Ltd. for providing

Athabasca River HEC-RAS Model data. This help enabled us to complete Stantec HEC-RAS

model analysis. Northwest Hydraulic Consultants Ltd. provided this model data under the

guidance of Woodlands County on October 14, 2014. HEC-RAS is a rigid boundary model and

does not account for any river streambed scour due to any constriction in river. The modelled

flow water levels would be higher than actual levels due to not being able to account for scour

which would reduce the water level elevation.



March 27, 2015


2.1.1 HEC-RAS Model

Open flood water surface profiles were calculated using River Analysis System (HEC-RAS

version 4.1.0) developed by Hydrologic Engineering Centre (HEC), which is a division of

the Institute for water resources (IWR), U.S. Army Corps of Engineers.

HEC-RAS system contains four one-dimensional river analysis components for: (1) steady

flow water surface profile computation; (2) unsteady flow simulation ;(3) movable

boundary sediment transport computations; and (4) water quality analysis.

We are using steady water surface profiles river analysis component to model Athabasca

River study reach. This component of the modeling system is intended for calculating

water surface profiles for steady gradually varied flow.

The basic computational procedure is based on the solution of the one-dimensional

energy equation. Energy losses are evaluated by friction (Mannings equation) and contraction/ expansion coefficient multiplied by the change in velocity head). The

momentum equation is utilized in situations where the water surface profile is rapidly

varied.

2.1.2 Model Input Data

The HEC-RAS program requires geometric, hydraulic and hydrologic data input to

compute water surface profiles.

HEC-RAS Model data (geometric, hydraulic and hydrologic data) provided by Northwest

Hydraulic Consultants Ltd. is the basis of Stantec Modeling.

Sketches SK-C2-1 to SK-C2-2 given in Appendix C2 of this report shows HEC-RAS Modell

cross-section locations (provided by Northwest Hydraulic Consultants Ltd).

Stantec September 2014 survey data (bathymetry and ground survey) were inserted in

the model for reaches in the vicinity of study area.

To calculate design flood (1:100 year) elevations at spur locations, cross sections were

inserted/interpolated in model at proposed spurs locations. These inserted/interpolated

cross sections were based on Stantec September 2014 surveyed data and Northwest

Hydraulic Consultants Ltd. HEC-RAS geometric data.

15 Spurs at the proposed location (see Design given in Appendix B of this report) along

the study reach were inserted in the model.

Berms are required between spurs #5 and #7 and other spurs are connected to higher

ground.



March 27, 2015


2.1.3 Modeling Results

Once the proposed spurs are added to the HEC-RAS model, the model is run WITH spurs in and

WITHOUT spurs in for design flood (1:100 year) and several other return period (2, 5, 10, 20 and 50

years) floods. The model results and comparison of two scenarios to assess impact on river

hydraulics are summarized in Table D1 and Figures D1 and D2 given in Appendix D.

2.1.3.1 Hydraulic Impact on Hwy 43 Bridge

Hwy 43 bridge is located approximately 1.1 km upstream of the most upstream proposed

spur (i.e. spur #1) measured along the river thalweg.

Spur #2, which is existing spur, is located 1.2 km downstream of Hwy 43 bridge along river

thalweg. Spur #2 will be reinforced with Class 3 rock since its apron and some of its slope

protection rock has been launched.

Spur #2 (existing spur) was not modelled in original HEC-RAS model provided by

Northwest Hydraulic Consultants Ltd. There is scour hole at station 2+280 downstream of

existing spur (see thalweg elevation profile Drawing S02-P given in Appendix B).

Table D1 and Figures D1 and D2 given in Appendix D, show modeling results for 1:100

and several other return period (2, 5, 10, 20 and 50 years) floods WITH spurs in and

WITHOUT spurs for study reach.

The results show that there is no impact (+/- 0.04 m) on 1:100 year flood water surface

elevations at section immediate upstream of Hwy 43 bridge due to installation of

proposed right (south) bank spurs. HEC-RAS is a rigid boundary model and does not

account for river streambed scour by itself due to constriction so practically speaking

there will be no impact on water surface elevation due installation of spur at Hwy 43

bridge.

Based on Alberta Transportation Hydrotechnical Information System (HIS), Hwy 43 Bridge

over Athabasca River has a minimum bottom flange elevation 695.6.

The results show that Hwy 43 bridge has a freeboard in the order of 1.7 m for 1:100 year

(design) flood with and without proposed right (south) bank spurs in place.

Discussion and Conclusion

In view of the above comments, there would be no hydraulic impact on Hwy 43 bridge due to

installation of proposed spurs in Athabasca River. Spur #2 is already installed in river and spur #1

footprints in river are similar to spur #2. There would be a minimum additional river constriction

due to spur #1, upstream of Athabasca/McLeod Rivers confluence.



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2.1.3.2 Hydraulic Impact on Pembina Pipeline Crossing Downstream of Study Reach

Pipeline crossings (Pembina Pipeline) right of way is located downstream of most

downstream proposed spur (i.e. spur #15).

There is an existing landslide along north bank approximately from station 5+900 to

station 6+700. Please note steep thalweg slope in this reach (see Drawing S03-P given in

Appendix B). Athabasca Rivers north channel is joining the south river channel just

upstream of pipeline right of way. Average channel slope for sub reach downstream of

confluence of the south and north channels is approximately1.0 %. Average river

channel slope of the study reach is approximately 0.2 %. This sub reach is approximately 5

times steeper than average channel slope in study reach. Much of this increased

channel slope is caused by the substantially reduced channel width and available flow

area downstream of the confluence of these two channels. This resulting scouring of the

channel bed has reduced the toe load of the left high valley wall likely contributing to its

instability and ultimate failure. A detailed geotechnical/hydrotechnical study would be

required to confirm and quantify these observations.

River channel is somewhat more confined (one channel) at this location with steeper

slope, which results in higher velocities (see Table D1 HEC-RAS results between XS12 and

XS13 in Appendix D). Moreover, river left bank is outer meander bank which results in

higher local velocities. Higher velocities have contributed to the rivers left (north) bank

instability (bed active erosion and scour at this location). Left (north) bank instability in

form of slumping was observed at this location during Stantec December 31, 2014 site

visit. Right (south) bank instability in form of lateral erosion was observed at this location

during Stantecs December 31, 2014 and September 08, 2014 site visits.



March 27, 2015


Photo 1 Looking at left (north) bank slump from right (south) bank, in the immediate

vicinity of pipeline crossing.



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Photo 2 Looking downstream along right (south) bank lateral erosion from right (south)

bank, upstream of pipeline crossing right of way (June 04, 2013 site visit). See

left (north) bank slumping.



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Photo 3 Looking left (north) bank from right (south) bank (June 04, 2013 site visit). Note

left (north) bank slumping.



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Photo 4 Looking upstream along right (south) bank lateral erosion from right (south)

bank, from pipeline crossing (December 31, 2014 site visit).

Table D1 and Figures D1 and D2 given in Appendix D, show modeling results for 1:100

and several other return period (2, 5, 10, 20 and 50 years) floods WITH spurs in and

WITHOUT spurs in for study reach.

The results show that there is no impact on 1:100 year (design) and several other return

period (2, 5, 10, 20 and 50 years) floods water surface elevations and corresponding

velocities at sub reach immediate downstream of spur #15 (pipeline right of way) due to

installation of proposed right (south) bank spurs.

Spurs #13, #14 and #15 would deflect Athabasca River south thalweg away from south

(right) bank towards main channel. This would result in improving the stability of south

(right) bank immediately downstream of spur #15. Flows from north Athabasca River

channel which are apparently greater than the south channel would cause the thalweg

to migrate to the middle of channel, downstream of mid channel island (see Plan shown

in Drawing S03-P in Appendix B) and downstream of pipeline crossing right of way.



March 27, 2015


The most downstream spur (spur #15) nose is located approximately, 200 m upstream of

the nearest operating pipeline.

Stantec contacted Pembina pipeline during design process. A summary of the

information received from Pembina Pipeline Corporation is provided below. This

information was provided by Kody Christianson, Pembina Pipeline Corporation.

The Athabasca River pipeline crossings were included in the Geotechnical Braided River

Study by Northwest Hydraulic Consultants Ltd. for the Pembina Pipeline Corporation.

There are three pipeline crossings in NW 01-60-12-W5. Some of the pertinent information is

provided below:

o A bank comparison was carried out at the pipeline crossings. Athabasca River

has shifted south, from 1991 to 2012, approximately 35 m along the pipeline

alignment.

o 1.2 m minimum depth (at thalweg) of cover within the waterbody exists, with

bank loss rate of 1.2 m/year and a low pipeline risk of exposure. This crossing may

require mitigation within next 10 years.

o At the pipeline crossing location, the estimated 1:100 year flood level at elevation

687.60, minimum bed elevation at 681.00, net scour depth 1.00 m and scour level

at elevation 680.00. All the elevations mentioned previously are geodetic.

Geohazards risk rating was provided but the description of the rating was not

provided. Therefore, the information in this table does not provide useful

information.

o Pembina Pipeline Corporation does not have any remediation plans for this

crossing in the immediate future.


Based on HEC-RAS modelling results and analysis presented above, slumping of left (north) bank

and lateral erosion of south (left) bank are natural on-going process due to confined river

channel, steeper slopes, higher local velocities and resulting scour. Proposed south (right) bank

spurs would not impact river hydraulics in this sub reach and would improve the stability of the

low south (right) bank downstream of spur #15.

Spur #15 nose is located approximately 200 m upstream of nearest operating pipeline. Local

scour around pier #15 would not impact integrity of Pembina pipeline. This would need to be

reviewed, if these proposed spurs are not constructed within five years, as natural river channel

changes will continue to occur without the proposed spurs in place.

2.1.3.3 Hydraulic Impact on Athabasca River Left (North) Bank

The Athabasca River in this study reach flows in a stream cut valley. Generally the top



March 27, 2015


width of the valley is in the order of 2.5 km with a valley depth of 75 m. The valley walls

are somewhat forested with some bed rock cliffs. There is also occasional slumping due

to valley wall instability. The valley flats upstream of Athabasca/McLeod Rivers

confluence are sparsely forested or shrub covered with limited disturbance.

Downstream of the confluence south of the valley much of the land area is under

cultivation. HEC-RAS sections show that river valley walls adjacent to river left (north)

bank are relatively steeper and higher in study reach.

The Athabasca River channel pattern in the area of the Town is split with many mid-

channel and point bars and large vegetated gravel bars (islands). The river is a mobile

bed river that is highly active with constant adjustments of its banks occurring due to

lateral erosion within the study reach and becomes more confined downstream of

the study reach. The bed material is gravel (D50 in the range 30 50 mm), with mostly

alluvial sand and gravel in the south (right) bank within the study area. Generally

there are terraces along the right (south) valley wall and old meander scars.

The detail of project background information is available in Stantecs July 2013 report

Whitecourt River Engineering Study and Conceptual Design of River Bank Protection

Works of the Athabasca River from Whitecourt River Boat Park to the Pipeline East of the

Golf Course prepared for Town of Whitecourt, Woodlands County and Millar Western

Forest Products Ltd. Sketches SK-04-01 to SK-04-03 given in Appendix A of Stantecs July

2013 shows the bank tracking of left (north) bank from year 1950 to year 2012. This bank

tracking shows that left (north) river channel is constantly adjusting its banks occurring

due to lateral bank erosion and or bank slumping. Evident of left (north) bank slumping at

pipeline crossing (Station 5+900 to Station 6+600) is shown in ground Photos 1 and 3 of

Section 2.1.3.2.

Table D1 and Figures D1 and D2 given in Appendix D, show modeling results for 1:100 and

several other return period (2, 5, 10, 20 and 50 years) floods WITH spurs in and WITHOUT

spurs in for study reach.

The modeling result shows the right (south) bank spurs impact on 1:100 year (design) and

several other return period (2, 5, 10, 20 and 50 years) floods water surface elevations and

corresponding channel velocities.

The results show that there is a minimum (+/- 0.1 m) to no impact on 1:100 year flood

water surface elevations at sections immediate upstream of proposed spurs #1 to #5.

The impact on 1:100 year flood water surface elevations at sections immediate

upstream of proposed spurs #6 to 9 is +/- 0.2 m. This assumes no bed scour, but in reality

considerable scour does occur during flood events and is expected to reduce

maximum water elevation from a maximum of 0.2 to likely less than 0.1 m. From spurs

#10 to #15 there is no impact on 1:100 year floods water surface elevations.

It is important to mention here that HEC-RAS is a rigid boundary model and does not



March 27, 2015


account for river streambed scour by itself. The actual flow elevations would be lower

than modelled flow water levels due to not accounting for scour drop in streambed

elevation.

The results shown in Table D1 given in Appendix D show that at sections immediate

upstream of spurs #1 to #9 there is a minimum to no impact on 1:100 year flood main

channel average velocities.

The change in main channel average velocities at sections upstream of spurs # 10 to 15

for 1:100 year are given below in Table 4.

Table 4 HEC-RAS Modeling Results

Spur Number

Vel Total Cross-

section Average

(STN+NHC) with

Spurs in Place

(G)

Vel Total Cross-section

Average (STN+NHC)

without Spurs in Place

(H)

Difference

in Vel

(I=G-H)

% Change

in Velocity

(m/s) (m/s) (m/s) (%)

18562.6_Spur #10 2.6 2.21 0.39 17.6

18232.55_Spur #11

_Unprotected 2.28 1.97 0.31 15.7

18089.55 A25 (XS 15)_Spur # 12 1.84 1.73 0.11 6.4

17903.55 _Spur #13 1.84 1.76 0.08 4.5

17820.09 A24 (XS 14) _Spur #14 1.68 1.63 0.05 3.1

17737.09_Spur #15 1.71 1.65 0.06 3.6

Notes: - STN represents Stantec and NHC represents Northwest Hydraulic Consultants Ltd.

Change in mid channel average velocities at sections immediate upstream of spur #12

to 15 is less than 7 %. At these spur locations it is anticipated that left (north) bank would

have minimum to no hydraulic impact due to right (south) bank spurs in place for 1:100

year flood event.

Changes in mid channel average velocities at sections immediate upstream of spur #10

and 11 are 17.6 % and 15.7 %, respectively. Average velocities along banks are generally

lower than average mid channel velocities due to higher resistance values (higher

mannings roughness value due to vegetation) along banks. Sketches SK-04-01 to SK-04-

03 given in Appendix A of Stantec July 2013 report shows the bank tracking of left (north)

bank from 1950 to 2012. It shows that left (north) bank of north river channel in sub reach



March 27, 2015


in the vicinity of spurs #10 and #11 (approximately from Station 4+400 to Station 5+400

along river thalweg) is stable and has mature vegetation along left (north) bank. Due to

higher bank roughness, changes in velocities along north bank would be lower than

average mid channel velocities once the spurs in place along right (south) bank.


Based on HEC-RAS results and analysis presented above, it is anticipated that left (north) bank

would have minimum hydraulic impact due to proposed spurs in place along right (south) bank.

Qualitatively speaking, from over all river system point of view this project would help to arrest

lateral right (south) bank erosion in study reach and would not increase erosional impact on left

(north) bank due to spurs in place (see Section 2.1.3.4 of this report).

2.1.3.4 Spurs Hydraulic Impact on Erosion of Athabasca River (River Banks, Mid-

Channel Bars and Streambed)

Please also see previous Sections 2.1.3.1 to 2.1.3.3.

The Athabasca River channel pattern in the area of the Town of Whitecourt is split

with many mid-channel and point bars and large vegetated islands. The river is a

mobile bed river that is highly active with constant adjustments of its banks occurring

due to lateral erosion within the study reach and becomes somewhat more

confined at the end of the study reach.

Study reach has four large mid-channel islands and several medium to small mid-

channel islands and point bars. Out of four large islands, three are mostly vegetated

and one just upstream of pipeline crossing is partially vegetated.

Sketches SK-04-01 to SK-04-03 given in Appendix A of Stantecs July 2013 report shows

the mid channel islands tracking from 1950 to 2012. This tracking shows that river mid-

channel islands and point bars are constantly changing due to lateral bank erosion

and or bank slumping ,and or deposition of river deposits/debris (during flood fall

stage).

All mid-channel islands and point bars would be under water for 1:100 year flood

event.

Stantec is monitoring this site through site visits (5 visits) from March 2013 to December

2014. Athabasca River is actively eroding right (south) bank in study reach (see June

04, 2013 and March 12, 2013 site visit ground photos given in Appendix C of Stantec

July 2013 report). The most recent river right (south) bank lateral erosion is noted

between spurs #1 and #2 location (see Photo 16 given in Section 2.1.3.4 of this report).

The Do Nothing Option was reviewed and the present and future risk to property



March 27, 2015


and the environment were considered to be too great for this reach of the river to be

left unprotected (see Section 3.6.1 of Stantec July 2013 report).

Please see the following photos taken during the September 2013 and December

2015 site visit to look at right (south) bank lateral erosion along study reach.

Photo 5 Looking upstream between spurs #6 and #7 from Millar Western property.



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Photo 6 Looking upstream between spurs #6 and #7.



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Photo 7 Looking downstream between spurs #7 and #8.



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Photo 8 Looking downstream between spurs #8 and #9.



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Photo 9 Looking upstream from 47 Street between spurs #9 and #10.



March 27, 2015


Photo 10 Looking downstream along golf course.



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Photo 11 Looking upstream along golf course.



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Photo 12 Looking downstream from golf course to pipeline right of way.



March 27, 2015


Photo 13 Looking downstream from golf course to pipeline right of way.



March 27, 2015


Photo 14 Looking upstream from spur #3 along McLeod River right (east) bank adjacent

to Miller Western property.



March 27, 2015


Photo 15 Looking upstream along Athabasca River right (south) bank at Boat Park. Note

existing spur #2 in upper middle of photo.



March 27, 2015


Photo 16 Looking upstream along Athabasca River right (south) bank from Boat Park

between existing spur #2 and proposed spur #1.


Based on discussion presented in previous Sections 2.1.3.1 to 2.1.3.3 and above analysis, major

mid-channel islands erosion and general streambed scour due to changes in main channel

average velocities would be minimum to none from spurs #1 to #9. There would be some

additional erosion and general streambed scour in the vicinity of spurs #10 and #11. Major mid-

channel islands erosion and general streambed scour due to changes in main channel average

velocities would be minimum from spurs #12 to #15.

Spurs are designed to straighten and realign flows in order to transfer the main attack by river

from a vital point to an expendable one. A spur has armored nose (end section). Deflected

flows from spurs may cause erosion of less vegetated island and local scour around nose of spur.

Scour holes around spur would provide good fish habitat. We anticipate that this erosion and

scour would not be greater than erosion and scour caused by natural river process (see

Sketches SK-04-01 to SK-04-03 given in Appendix A of Stantec July 2013 report).



March 27, 2015


Qualitatively speaking, from over all river system point of view, this project would help to arrest

lateral south bank erosion in study reach and would offset any erosion and or scour caused by

the proposed right (south) bank spurs.

2.1.3.5 Installation of 3.0 m Diameter CSP Pipe under Spur #10 for Fish Connectivity and

Pipe Maintenance

Spur #9 length has been reduced without affecting its performance. At this location

approximately 45 % width of the most south river channel (adjacent to right (south) river

bank) at September 2014 water level is open (see Drawings S02-P, S06-P and S13-P in

Appendix B).

Spur #10 length has been reduced, however, spur effective length required to deflect

flows away from attacking on right (south) bank in this sub reach is 85 m. This length of

spur blocks the most south river channel (see Drawing S03-P given in Appendix B).

Athabasca River at spur #10 has three distinct channels at this location: the north,

channel, mid channel (main channel) and the south channel (see drawing S03-P in

Appendix B). Based on Google earth imagery, width of these channels perpendicular to

bank at water level elevation are approximately 70 m, 135 m and 55 m, respectively. The

width of south channel is in the order of 20 % of total available Athabasca River channel

width at water level elevation at this location. The Athabasca River regime channel

width is approximately 150 m, i.e. similar to the channel width at the Highway 43 bridge.

Surveyed cross-sections of mid and south river channels are shown in drawing S14-P given

in Appendix B (see cross-section 5).

The total opinion of costs for spur #10 protection works is $875,000 (2,513 m3 X $320 / m3 of

Class 3 rock + 4,667 m3 X $15/ m3 of common fill) including contingencies and

engineering costs. The estimated costs will need to be refined and are subject to the

availability of Class 3 rock. This cost does not include possible fish habitat compensation

costs.

The total opinion of costs for rock riprap bank protection works from Station 4+027 to

4+800 (along river thalweg) to replace spur 10 is $5.1 M (16,000 m3 X $320/m3) including

contingencies and engineering costs. The estimated costs will need to be refined and

are subject to the availability of Class 3 rock. This cost does not include possible fish

habitat compensation costs.

Alberta Transportations HydroChan computer modeling tool was utilized to estimate the

mean velocity and the water level elevation for Q2 and Q100 flows through Athabasca

River right (south) channel. HydroChan is a rating curve calculator for open channel flow.

The assessment was carried out based on a Mannings n of 0.032 for the main channel

and 0.05 and 0.07 for left and right overbanks. Mannings n values were based on HEC-



March 27, 2015


RAS Model provided by Northwest Hydraulic Consultants Ltd., field assessment and

experience. HydroChan results are presented in Table 5.

Table 5 Estimated Channel Mean Velocity and Water Level Elevation for Q100 and Q2

Return Period Estimated Flow

(m3/s)

Mean Velocity

(m/s)

Water Level Elevation

(m)

Q2 190 1.5 687.0

Q100 1370 2.7 689.6

A single 3.0 m CSP culvert with an invert length in the order of 32 m under 2.0 m of fill from

top of spur to top of culvert at 0.2 % slope (streambed slope) would be installed on

square to spur #10 centerline to provide fish connectivity during low flows. Culvert would

be placed at streambed elevation to avoid ponding in culvert, which may trap fish. It is

anticipated that any moderate flood would further develop the existing channel around

the upstream end of the spur and most of the channel flow would follow this channel.

We have modeled a single 3.0 m diameter CSP culvert with an invert length of 32.0 m

with a theoretical streambed centerline elevation of 684.7 m with no pipe burial depth

on a 0.2 % slope for the Q2 and Q100 flow and downstream boundary conditions. The

culvert is modelled for outlet control condition and it is anticipated that culvert both inlet

and outlet ends are submerged and water level at both ends would be the relatively the

same for different return periods. Table 6 summarizes the hydraulics of the proposed

structure.

Table 6 Hydraulics of a Single 3.0 m Diameter CSP Culvert

1-3.0 m diameter - Steel Round Pipe Culvert

Flow

Natural Channel Proposed Culvert

Flow

(m3/s)

Depth

(m)

Velocity

(m/s)

Flow

Through

Pipe

(m3/s)

Mean Velocity

at Inlet

(m/s)

Mean

Velocity at

Outlet

(m/s)

Freeboard

(m) and comments

Q1:2 Year Fish

Passage Flow 190 1.2 1.5 4 0.7 0.7

0.6 and under a head

difference of 0.2 m

Q100 1370 1.1 2.6 4 0.6 0.6 Submerged Pipe under a

head difference of 0.4 m



March 27, 2015


The design flow (Q2) velocity for fish passage through the designed 3.0 m diameter CSP

culvert are less than that of the natural channel. This pipe would not be a fish obstruction

and would provide fish connectivity during low flows.

It is anticipated that any sediment deposits in the pipe would move downstream during

a moderate flood.

From a fisheries perspective, the culvert design should be at bed level (or at least doesnt

have an embedded outlet) to prevent stranding, and installed at a slope that matches

the river bed. The intent is to maintain a small side channel that maintains small-water

habitat for small-bodied fish (fry and rearing sport fish, as well as coarse & forage fish).


Based on the hydrotechnical analysis presented above, site visits, bathymetry survey, hydraulic

calculations, engineering judgment and experience, a single 3.0 m diameter CSP culvert with an

invert length of 32.0 m with a theoretical streambed centerline elevation of 684.7 m with no pipe

burial depth on a 0.2 % slope would be installed under spur #10 for fish connectivity.

Upon review of the options and issues considered above in Section 2.1.3.3 and in Sections 3.1 to

3.3 of this report and considering cost, technical feasibility, installation, hydraulic performance,

environmental impact and long term functionality, we recommend to install spur #10. Long spur

protection works option is more cost effective ($0.9 M vs $5.1 M) and has considerably less

environmental impact than rock riprap bank protection works option.

A previous example of blocking or restricting one channel of a split or twin river channels was

carried out by Alberta Transportation approximately in 1972. The location was on Highway 88

over the Peace River near Ft Vermilion. The south channel was blocked by the highway

embankment and the north channel was completely bridged. A 3.0 m +/- SPCSP culvert was

installed in the south channel in the highway fill. It has apparently been working well and

allowing fish passage through this culvert.

2.1.3.6 Spurs Hydraulic Impact on McLeod River and Athabasca River Ice Jams

The summary of Athabasca/McLeod Rivers flooding near Whitecourt due to ice jam is

given below in Table 7.



March 27, 2015


Table 7 Athabasca and McLeod Rivers Ice Jam Events

Date Cause of Flooding

April 17-24, 1963 Ice Jam in McLeod River

April, 1960 Ice Jam in Athabasca River

April, 1958 Ice Jam in McLeod River

April, 1948 Ice Jam in McLeod River

April 13-16, 1943 Ice Jam in McLeod River

April 20, 1940 Ice jam in Athabasca River and water level were

highest in recent memory in Athabasca River

April, 1926 Ice jam in Athabasca River

Source: Alberta Environment and Sustainable Resources Development draft report Whitecourt Floodplain

Study dated September 09, 2010.

Design condition on the McLeod River is ice jam scenario. Ice jam events in McLeod

River mostly occurred in April during breakup.

The following bullet provides an extract from the Woodlands County Flood Hazard

Identification Study, Athabasca and McLeod Rivers at Whitecourt draft report prepared

by Northwest Hydraulic Consultants Ltd. dated March 7, 2013.

o In the Athabasca River, the multi-channel planform limits the severity of ice jams

because of the multiple flow paths that are available to convey flows around an

ice accumulation. The most severe flood levels are expected to occur when an

ice jam is confined to a single channel: such is the case in the lower reaches of

the McLeod River. Also, at the confluence, ice jams may form against intact ice

in the Athabasca River. In spring the McLeod River often breaks up before the

Athabasca River, which has the potential to lead to the formation of large ice

jams at the mouth of the McLeod River (Kellerhals, et. al. 1972).

As mentioned previously, ice jams may form at the confluence against the intact ice in

the Athabasca River. As an ice run reaches a confluence, its momentum generally is

decreased due to the significant increase in channel size where the two rivers join. This

process will still occur after the proposed spurs are built.



March 27, 2015


The proposed spurs #3 and #4 just downstream of confluence, along the Athabasca

River are relatively short with their length being approximately 7.5 % and 12.3 %

respectively of the rivers south channel width at September 2012 water level elevation.

The proposed spurs effect on ice jam formation is anticipated to be small due to the

spurs short length and also the multi-channel planform of the Athabasca River which

limits the severity of ice jams.

Open water flooding is the design condition for the Athabasca River in the reach of the

proposed works; however ice jam flooding also occurs in the Athabasca River. The

following bullet provides an extract from the Alberta Environment and Sustainable

Resources Development draft report Whitecourt Floodplain Study, dated September

09, 2010.

o From resident interviews, the toe of the ice jams on the Athabasca River has been

placed at a couple of locations. The Western Lumber Company had an ice

bridge about 3 miles (4.8 km) upstream of the ferry crossing during this period.

Several residents thought that it had caused the ice jams, as it was always the last

ice to break up; however there are no eye witness reports to that effect. A

documented toe location was at the upstream end of Five Mile Island on SW16-

60-8-W5M.

During winter, Albertas rivers are generally covered with ice. This natural phenomenon

can cause important damages during ice jam events. An ice jam occurs when the

passage of river ice floes is obstructed by natural or man-made obstacles, which in some

cases may cause the water level to rise beyond open water flood elevations. Ice jam

formation is a complex phenomenon influenced by hydrometeorological factors such as

snow melt, air temperature, solar insolation, rainfall, channel geometry, stream flow,

water level, ice thickness, etc. Certain locations are conductive to the formation of ice

jams and so jams tend to form at these locations repeatedly whenever conditions are

favorable. As mentioned above the documented ice jam toe location for Athabasca

River was at the upstream end of Five Mile Island on SW16-60-8-W5M, which is 45.5 km

downstream of Athabasca/ McLeod rivers confluence. The summary of Athabasca River

channel constriction at proposed spurs location in study area at September 2012 water

level elevation is given below in Table 8.



March 27, 2015


Table 8 Athabasca River Channel Constriction at Proposed Spurs Location at September

2012 Water Level Elevation

Spur #

Spur

Length (m)

From

September

2012 Edge

of Water

Channel Width (m) at September

2012 Water Level Elevation % Reduction in

Channel Width at

September 2012

Water Level

Elevation

Comments

North Middle South

1 26 50 0 123 15%

2 17 40 0 92 13% Existing Spur

3 15 53 0 107 9%

4 21 47 0 170 10%

5 32 51 33 187 12%

6 25 72 25 218 8%

7 45 75 113 193 12%

8 51 55 247 13 16%

9 39 65 149 64 14%

10 49 72 147 56 18%

Spur obstruct

south channel.

Mid (main)

channel is open

to convey ice

during ice

breakup event.

11 0 72 188 30 0% Spur on Gravel

Bar

12 45 63 120 103 16%

13 30 64 77 66 14%

14 31 45 113 113 11%

15 26 23 80 103 13%

Note: Channel width is based on September 2012 aerial imagery provided by Town of Whitecourt.

The proposed spurs along the Athabasca River are relatively short with their length being

approximately in the range of 0 % to18 % of the rivers channel width at September 2012



March 27, 2015


water level elevation. The proposed spurs effect on ice jam formation is anticipated to

be small due to the spurs short length and also the multi-channel planform of the

Athabasca River.


The following discussion and conclusion are based on the analysis presented above.

The proposed spurs #3 and #4 just downstream of confluence, along the Athabasca River are

relatively short with their length being approximately 7.5 % and 12.3 % respectively of the rivers

south channel width at September 2012 water level elevation. The proposed spurs effect on ice

jam formation is anticipated to be small due to the spurs short length and also the multi-channel

planform of the Athabasca River which limits the severity of ice jams.

Ice jam formation is a complex phenomenon influenced by hydrometeorological factors such

as snow melt, air temperature, solar insolation, rainfall, channel geometry, stream flow, water

level, ice thickness, etc. Certain locations are conductive to the formation of ice jams and so

jams tend to form at these locations repeatedly whenever conditions are favorable. As

mentioned above the documented ice jam toe location for Athabasca River was at the

upstream end of Five Mile Island on SW16-60-8-W5M, which is approximately 45.5 km

downstream of Athabasca/ McLeod Rivers confluence. The proposed spurs along Athabasca

River right (south) effect on ice jam formation in Athabasca River in vicinity of study area is

anticipated to be small due to the spurs short length and also the multi-channel planform of the

Athabasca River.

2.1.3.7 Hydraulic Impact (Raise in Design Water Level Elevation) on River in Study

Reach

Please see Sections 2.1.3.1 to 2.1.3.4 of this report.

HEC-RAS is a rigid boundary model and does not account for river streambed scour by

itself due to constriction caused by spurs in river. The modelled flow water levels would

be higher than actual due to not accounting for scour drop in streambed elevation.


Based on HEC-RAS results and analysis presented above, it is anticipated that spurs construction

would have minimum to no impact on river hydraulics.

Qualitatively speaking from over all river system point of view, this project would help to arrest

lateral right (south) bank erosion in study reach and would offset any impact on river hydraulics

(see Section 2.1.3.4 of this report).


Alternative River Bank Protection Works Options

March 27, 2015


3.0 ALTERNATIVE RIVER BANK PROTECTION WORKS

OPTIONS

Brief descriptions of the different options considered are provided below.

3.1 DO NOTHING OPTION

The July 2013 report entitled Whitecourt River Engineering Study and Conceptual Design of

River Bank Protection Works of the Athabasca River from Whitecourt River Boat Park to the

Pipeline East of the Golf Course by Stantec discussed the Do Nothing Option in detail in Section

3.6.1. The investment value of Millar Western land and facilities is greater than $500 million and is

the greater source of employment in Whitecourt. Millar Westerns effluent pond is adjacent to

the river and any interruption to the ponds operation could be catastrophic to their operation.

Over 70 m (in perpendicular width) of bank was lost in the last year immediately downstream of

the Pond, bringing the overall situation to the forefront. Approximately 400 m (in perpendicular

width) of bank, at the pipeline crossing, has been lost since 1950, i.e. an average loss of 6 m per

year over the past 62 years. 3. Proposed Town sub-division lands - some 45 lots could become at

risk if lateral erosion and loss of the south bank is allowed to continue. Approximately 80 m (in

perpendicular width) of bank has been lost just upstream of Hole. #3 since 1996 (see SK-E-02

given in Appendix A of Stantec July 2013 report). To construct one new hole is estimated to cost

in the order of $350,000 which does not include the cost of the land required for the new hole.

Some 70 m (in perpendicular width) of the bank of towns Boat Park has been lost to erosion

since 1950 and additional loss of lands will occur if action to protect this area is not taken. The

proposed work at the Boat Park will provide some benefits to the lands immediately downstream

(Millar Western industrial site).

3.2 ADVANTAGES OF LONG SPURS VS ROCK RIPRAP BANK

PROTECTION WORKS

The advantages of long spurs installation are listed below.

There is a greater potential for the creation of fish habitat than the other design options.

Rock riprap bank protection generally performs the best where the protection works can

be placed parallel to the river flows. This type of protection work must extend far enough

upstream to prevent a meander from forming behind the upstream end of the

protection works. For this reach of river main and secondary river channel flows are

generally not parallel to its banks and the river meander pattern is irregular.



March 27, 2015


Installation of spurs in the river will help to form larger dead water pockets. The reduced

velocity along river bank will help debris to stay along banks. This debris may be

beneficial to enhance the fish habitat.

Clearing of vegetation required for construction and placement of spur fills to be

minimized. Stumps and roots system to remain in place.

Rock riprap bank protection works would disturb a greater amount of riparian vegetation

along right (south) river bank and may have harmful impact on fish habitat. Compared

to rock riprap protection works, the option of utilizing spurs will have much smaller foot

print and reduce the amount of vegetation requiring removal. Fish habitat

compensation required for rock riprap protection works would me much more than spurs

protection works.

Spurs bank protection option is more cost effective than rock riprap bank protection

($7.6 M vs $20.0 M). See Section 3.3 of this report for additional details.

Debris stuck on islands and mid channel bars and along banks will not be removed.

Scour holes around spur nose would provide good fish habitat.

The construction process will not be significantly different than the other, but rock riprap

bank protection construction along study area bank would require much bigger

instream isolation works compared to spurs construction.

The spurs offer bank protection and minimize the risk of future channel migration, while

offering the most natural-looking solution of the three options.

From a long-term fisheries health perspective, fewer, better-planned structures are more

desired and useful than continuous riprap or closely spaced structures for channel

restoration (Thompson 2002).

3.3 OPINION OF PROBABLE COST ESTIMATE OF LONG SPURS VS

ROCK RIPRAP BANK PROTECTION WORKS

Design drawings provided in Appendix B show the layout plan of spurs along Athabasca River

right (south) bank which features 14 rock protected long spurs, one unprotected spur extending

into the river channel providing bank protection. These spurs are composed of alluvium fill with a

riprap fascia. Based on available funds allocation, this project would be completed in two

phases. For project phasing, several mini spurs have been designed as shown on Drawing S01-P.

Based on Alberta Transportations rock riprap design criteria, Class 3 rock riprap (i.e. max size 1.1

m) is recommended for the spurs. The rock size and the configuration of the (spurs) river

protection works is designed to protect the integrity of the public and private lands along study



March 27, 2015


reach while taking into consideration the characteristics of Athabasca River. The Class 3 rock

requirement for right (south) bank spur protection works is given in Table 9.



March 27, 2015

ma u:\113530338\detailed_design\structures\report\report_final\report\rpt_design_protection_works_whitecourt_20150327.docx 3.38

Table 9 Description of Spurs Option

Spur Number

(Drawings

given in

Appendix B)

Stationing

along

River

Thalweg

(Km + m)

Spur Angle

of Upstream

Pointing

(Degrees)

Spur Length

from

Centerline of

Nose to Top of

Bank (m)

Spur Quantities

Comments

Class 3 Rock

(m3)

Fill

(m3)

1 2+120 15 20 1444 1820 Rock Protected

2 2+210 15 Existing spur 978 0

This is an existing rock

protected spur and will

be reinforced since its

apron has launched.

3 2+585 15 25 1427 2649 Rock Protected

4 2+800 15 15 1446 2683 Rock Protected

5 3+050 15 25 1373 2863 Rock Protected

6 3+270 15 20 1269 2155 Rock Protected

7 3+475 15 40 1446 3723 Rock Protected

8 3+730 15 50 1711 2443 Rock Protected

9 4+100 15 35 1561 2947 Rock Protected

10 4+525 15 85 2513 4667 Rock Protected

11 4+800 15 125 0 3663 Unprotected Spur

12 5+110 20 40 1874 4367 Rock Protected

13 5+250 15 25 1538 2923 Rock Protected

14 5+400 15 25 1485 3370 Rock Protected

15 5+530 15 20 1709 2147 Rock Protected

Mini Spurs

2A, 3A, 4A,

5A and 6A

1693 1945

Notes: - Total Class 3 rock requirement for spur protection works would be 23,467 m3.

- Total fill requirement for spur protection works would be 44,400 m3.

- The total opinion of costs for spur protection works is $8.2 M (23,467 m3 X $320/m3 of Class 3 rock +

44,400 m3 X $15/m3 of common fill) including contingencies and engineering costs. The estimated

costs will need to be refined and are subject to the availability of Class 3 rock. These costs do not

include fish habitat compensation costs.



March 27, 2015


Class 3 rock requirement for rock riprap protection works is provided in Table 10.

Table 10 Description of Rock Riprap Protection Option

Serial No.

Star Stationing along River

Thalweg

(Km + m)

End Stationing along River

Thalweg

(Km + m)

Class 3 Rock

(m3)

1 2+047 2+366 6678.2

2 2+529 2+746 4882.6

3 2+746 2+966 4505.0

4 2+966 3+217 4639.2

5 3+217 3+403 3638.3

6 3+403 3+682 5822

7 3+682 4+027 4592.8

8 4+027 4+402 9309.4

9 4+402 4+981 11273.4

10 4+981 5+179 3366.1

11 5+179 5+326 3403.8

12 5+326 5+646 7821.8

Notes: - Total Class 3 rock requirement for rock riprap protection works would be 62,800 m3.

- Class 3 rock requirement for rock riprap protection works would be 3.4 times of Class 3 rock

requirement for spur protection works.

- The total opinion of costs for rock riprap bank protection works is $22.4 M (69,800 m3 X $320/m3)

including contingencies and engineering costs. The estimated costs will need to be refined and

are subject to the availability of Class 3 rock. This cost does not include fish habitat compensation

costs.


Upon review of the options and issues considered above in Sections 3.1 to 3.3 of this report and

considering cost, technical feasibility, installation, hydraulic performance, environmental impact

and long term functionality, we recommend to install spurs along study reach to protect

Athabasca River right (south) bank in the vicinity of Town of Whitecourt. The spur protection

works option is more cost effective and has considerably less environmental impact than rock

riprap bank protection works option.


Geotechnical Investigation

March 27, 2015


4.0 GEOTECHNICAL INVESTIGATION

Athabasca River right (south) bank in the vicinity of streambed elevation is composed of river

deposits (mostly granular) along study reach. This material is easily erodible against river flows if

directly impinging on bank. Once the mature vegetation is lost along bank, right (south) bank is

more prone to erosion. The following list provides the description of the geotechnical desktop

study and Stantec geotechnical investigation along study reach.

Boreholes TH98-02, TH11-1, TH11-4, BH14-01, BH14-02 and BH14-03 are located along

Athabsca River right (south) bank along study reach and are shown on Drawings S02-P

and S03-P in Appendix B.

Borehole TH98-02 is located at Hwy 43 bridge this information was received from Alberta

Transportation and is given in Appendix E1. This borehole log shows that material in

vicinity of river bed elevation is Gravel; compact to dense, coarse grained, brown,

rounded to sub rounded cobbles, some sand, trace silt.

Boreholes TH11-1 and TH11-4 are located at Millar Western property adjacent to spurs #5

and #6. This information was provided by Millar Western and is given in Appendix E2.

These boreholes log show that material in vicinity of river bed elevation is Gravel:

compact to very dense, some sand, clay, and silt, trace sand and silt.

Stantec was retained by Town of Whitecourt to carry out at specific borehole locations

along study reach (Boreholes BH14-01, BH14-02 and BH14-03). This geotechnical

investigation report is included in Appendix E3. Borehole BH14-01 is located adjacent to

spur #8. Borehole BH14-02 is located adjacent to spur #10. Borehole BH14-03 is located

adjacent to spur #15 close to pipeline crossing. These boreholes log show that material in

vicinity of river bed elevation is Gravel (60 % to 72 %), Sand (22 % to 32 %) and Fines (6%

to 8%).

Sketches SK-C2-1 to SK-C2-2 given in Appendix C2 shows estimated bed rock elevation

based on available boreholes information given in Appendix F of this report.

4.1 DESIGN SCOUR DEPTH

Based on geotechnical analysis presented above, site visits, bathymetry survey, hydraulic

calculations, engineering judgment and experience the maximum potential scour at the nose of

the spurs is 5 m below the streambed thalweg elevation. Based on the borehole information

obtained the top of bedrock is below the maximum potential scour and will not limit the

potential scour depth. Based on this scour depth a launching apron of 5.0 m length with two

layers of Class 3 rock is designed for spur protection works. Based on past experience, research


Environmental Assessment and Regulatory Approvals

March 27, 2015


studies and field case studies providing launching apron lengths beyond 5 m in width is not

effective. The proposed launching apron would provide stability to rock placed along the side

slopes of spur.

5.0 ENVIRONMENTAL ASSESSMENT AND REGULATORY

APPROVALS

Stantec is carrying out environmental assessment and regulatory approval for this project.

Considerable effort will be required to mitigate the environmental impacts posed by the

proposed protection works. This project does not fall within the criteria of the Code of Practice

as an approval under the Water Act (Alberta Environment and Sustainable Resource

Development [ESRD]) is required. A license of occupation is required for permanent

implementation of river bank protection under the Public Lands Act (ESRD). Permission will be

obtained to do river bank protection works and special precautionary measures will be

implemented during construction. A Request for Review will be submitted to the Department of

Fisheries and Oceans (DFO) to determine if compensation or an approval will be required for

the protection works. A Notice of Works application will be sent to Transport Canada for review

under the Navigable Protection Act to obtain an approval if required.

6.0 CONCLUSIONS AND RECOMMENDATIONS

Lateral erosion of the river bank along this reach of the Athabasca River is ongoing and is a

naturally occurring phenomenon as the river is constantly changing its flow pattern even with

minor flood events. River protection works have been constructed at the two Highway 43

bridges over the McLeod and Athabasca Rivers in order to prevent the bridge from being

severely damaged during major flood events. The protection works have performed quite well

but do need monitoring and be inspected after major flood events and/or every 5 years.

Athabasca River right (south) bank in the vicinity of streambed elevation is composed of river

deposits (mostly granular) along study reach. This material is easily erodible against river flows if

directly impinging on bank. Once the mature vegetation is lost along bank, right (south) bank is

more prone to erosion.

The existing alignment of the main river channel is now more or less directly attacking several

areas of the river bank and it is important that action be initiated to prevent the loss of lands

adjacent to the right river bank in the study reach. What has occurred is that much of the buffer

zone of trees adjacent to the river has been lost over the years and lateral erosion can now


Conclusions and Recommendations

March 27, 2015


occur at a faster pace and continue to remove vegetation and lands. The environmental

impact due to the loss of property, large trees and established vegetation is considerable

including the fisheries habitat.

The conclusion reached from the analysis given in this report is that immediate action,

i.e. 2015, is required or future land and environmental losses will only increase as well as the

remedial river protection costs. The Do Nothing Option was reviewed and the present and

future risk to property and the environment were considered to be too great for this reach of the

river to be left unprotected. Upon review of the options and issues considered above in Sections

3.1 to 3.3 of this report and considering cost, technical feasibility, installation, hydraulic

performance, environmental impact and long term functionality, we recommend to install spurs

along study reach to protect Athabasca River right (south) bank in the vicinity of Town of

Whitecourt. The Spurs protection works option is more cost effective ($7.6 M vs $22.4 M) and has

considerably less environmental impact than rock riprap bank protection works option.

This project is for the construction of 14 spurs constructed with fill material, one existing spur (spur

#2) reinforced with Class 3 rock (max size of rock 1.1 m) and several mini spurs. 13 of the 14 spurs

will be armored with Class 3 rock riprap. The spurs are being constructed to prevent the

Athabasca River from migrating to the south along this reach and putting land, properties and

utilities at risk. Based on funding allocation for this project this year, construction in phases is

recommended. As phase 1 construction; reinforcement of spur #2 and construction of spurs #3,

#4, #6, #7 and #10 and the mini spurs would be a priority this year. If funds dont allow for all of

the Phase 1 works then possibly spur #4 and #10 may need to be dropped.

The Restricted Activity Period (RAP) for the Athabasca River upstream of its confluence with

McLeod River is September 01 to July 15th and September 1 to June 30th downstream of the

confluence. Due to the large extent of the project and the nature of the work, the construction

of spurs in the least sensitive river habitats may have to occur within the RAP. Based on flows in

Athabasca and McLeod River (see Section 2.0 of this report,) instream works, including the

placement of rock and fill for the spurs, would best occur from September 01 to November 30.

Qualitatively speaking from an overall river system point of view, this project would help to arrest

lateral south bank erosion in this study reach and would offset any impact on river hydraulics in

study area due to spurs in place.

There will be no hydraulic impact on the Hwy 43 bridge due to installation of proposed spurs in

Athabasca River. Spur #2 is already installed in river and spur #1 footprints in river are of similar to

spur #2. There will be a minimum additional river constriction due to spur #1, upstream of

Athabasca/McLeod Rivers confluence.

Slumping of left (north) bank and lateral erosion of right (south) bank are natural on-going process

at Pembina pipeline crossing due to confined river channel, steeper slopes and higher local

velocities. Proposed south (right) bank spurs would not impact river hydraulics in this sub reach and

would add some stability to low south (right) bank downstream of spur #15. Spur #15 nose is


Conclusions and Recommendations

March 27, 2015


located approximately, 200 m upstream of nearest operating pipeline. Local scour around pier

#15 would not impact integrity of Pembina pipeline. This would need to be reviewed, if these

proposed spurs are not constructed within five years, as natural river channel changes will

continue to occur without the proposed spurs in place.

It is recommended that the Town of Whitecourt establishes a monitoring program that will

schedule inspections of the bank protection works after significant flood events (1:10 year) or at

a minimum of every five years to identify any problems or maintenance required. This monitoring

should include soundings of the streambed at the spurs to record and determine the scour that

may have taken place and conducted during low flows to assist in determining that the stability

of the toe of the slope is maintained. The smaller rock can be carried away by strong currents,

and sections of rock riprap may settle due to poorly consolidated substrate.

It is also recommended that all phases of this project should be constructed as soon as funds

can be allocated to this project as the active lateral erosion is affecting this complete study

reach. Pipeline owner should be contacted to advise them of this proposed work as they are

downstream and their crossing may be affected by any protection works constructed

upstream. This may be of benefit to them as there would be some efficiency in combining their

reach with this reach in the detailed study.

From a river engineering viewpoint, it is recommended that all phases of this project be

combined, probably in one contract, as there would be some efficiency in construction,

contract preparation and environmental costs. As well there would be a considerable

reduction in risk to the three parties as delaying next phases may increase the loss of lands and

increase the costs of protection works.


Closing

March 27, 2015


7.0 CLOSING

This document entitled Design of Athabasca River Erosion Control Protection Works at

Whitecourt, Alberta " was prepared by Stantec Consulting Ltd. for the Town of Whitecourt and

Woodlands County. This report was prepared to response to comments received during the

meeting with Alberta Environment and Sustainable Resource Development (ESRD) on January 28,

2015 in Spruce Grove, AB.

The material in this report reflects Stantec Consulting Ltd's best judgment in light of the

information available to it at the time of preparation. Any use which a third party makes of this

report, or reliance on or decisions made based on it, are the responsibilities of such third parties.

Stantec Consulting Ltd. accepts no responsibility for damages, if any, suffered by any third party

as a result of decisions made or actions based on this report.

Prepared by: Reviewed by:

Arshed Mahmood, M.Sc., P.Eng. Ralph Walters, M.Eng., P.Eng.

Bridge Planning and River Engineer Senior Bridge Planning and River Engineering

Specialist

APPENDIX A Stantec Responses to ESRD Comments

gc u:\113530338\detailed_design\structures\report\report_final\appendices\a_response to aesrd\table form_113530338_internal_telecon_2 12 2015_action items_ph (2).docx

TABLE A1: Stantec Consulting Ltd. Response to ESRD January 28, 2015 Comments (also see March 27, 2015 design report by Stantec)

ACTION ITEMS RESPONSE

A. Following comments from German Rojas, Hydrologist, AESRD Stantec Response to: German Rojas Comments

1. A clear statement of the consequences of the river training works on the Hwy 43 bridge. A letter of acknowledgement from Alberta Transportation should be included.

Issued a letter to Alberta Transportation (AT) and will forward AT response to AESRD. Please see Section 2.1.3.1 of this report. There would be no hydraulic impact on Hwy 43 bridge due to installation of proposed spurs in Athabasca River. Spur #2 is already installed in river and spur #1 footprints in river are of similar to spur #2. There would be no additional river constriction due to spur #1, upstream of Athabasca/McLeod Rivers confluence.

2. A figure displaying the lateral movement of the Athabasca River at the project site including spur locations. This would determine that the aimed location of the right bank would be the same as for example the year 2000.

Please see Sketches SK-C1-1 to SK-C1-3 given in Appendix C1 of this report.

3. Figure 4 of the Design Drawings set indicated that spurs 9 and 10 would connect the right bank to an existing sand island which would completely block the flow thorough the Thalweg identified as Profile 3. To a question during the meeting on how to avoid a complete blockage of this area, the possibility of installing culvert was expressed by the consultants. This option should be fully described in the report including maintenance works since the culvert would be located in a sediment deposition zone between the two spurs.

Please see Section 2.1.3.5 of this report and Design given in Appendix B (Drawings S06-P, S07-P and S11-P). Based on the hydrotechnical analysis, site visits, bathymetry survey, hydraulic calculations, engineering judgment and experience a single 3.0 m diameter CSP culvert with an invert length of 32.0 m with a theoretical streambed centerline elevation of 684.7 m with no pipe burial depth on a 0.2 % slope would be installed under spur #10 for fish connectivity. It is anticipated that any sediment deposits in the pipe would move downstream during a moderate flood. A previous example of blocking or restricting one channel of a split or twin river channels was carried out by Alberta Transportation approximately in 1972. The location was on Highway 88 over the Peace River near Ft Vermilion. The south channel was blocked by the highway embankment and the north channel was completely bridged. A 3.0 m +/- SPCSP culvert was installed in the south channel in the highway fill. It has apparently been working well and allowing fish passage through this culvert.

Spur #9 was redesigned so that it does not block all of the existing side (south) channel and a

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