CR 6 - Hydrology - Alberta · 2017. 5. 31. · Hydrology Assessment Project 17470, Sept 5, 2012 2 2...

VALUE CREATION INC.

ADVANCED TRISTAR PROJECT HYDROLOGY ASSESSMENT

SEPTEMBER, 2012

ADVANCED TRISTAR PROJECT HYDROLOGY ASSESSMENT

Prepared for: Value Creation Inc. 1100-635 8 Avenue SW Calgary, AB T2P 3M3

Prepared by: Northwest Hydraulic Consultants Ltd.

9819 – 12 Ave SW Edmonton, AB, T6X 0E3

September, 2012 APEGGA Permit P00654

NHC project #17470

VCI ATS Project Hydrology Assessment Project 17470, Sept 5, 2012 i

EXECUTIVE SUMMARY

The regional and local baseline surface water hydrology for Value Creation Inc. (VCI’s) Advanced TriStar (ATS) Project was described and mapped and historical climate and streamflow data were evaluated. Local water levels, streamflows, channel geometry and snow depths were measured. Flow variability was evaluated from the regional data and from a Hydrologic Simulation Program Fortran (HSPF) model calibrated to regional data and validated with local data.

The hydrology evaluation assessed existing and approved development and the Project development. The existing and approved development was found to increase annual runoff volumes by up to 1.0% in some local watersheds relative to conditions defined by the regional hydrology. The Project development is expected to increase annual runoff by up to 4.5% relative to these regional conditions. Average peak flows may increase as much as 2.6% in some areas and there are no perceptible changes in the timing of peak flows. Changes in magnitude of annual minimum flow rates appear to be large on a percentage basis in some of the watersheds, however, they are very small flow rates. In most of the watersheds the net effect will be less years with zero flow.

Annual peak water levels and surface areas in the streams and ponds may change slightly due to changes in annual peak flow. These changes will be imperceptible compared to natural variability. Minimum water levels and surface areas may be slightly higher due to increased minimum flows; however, zero flows will still occur in most of these small watersheds.

Channel morphology and sediment concentrations will not change due to the application development case because changes to the flow regime are small, and because roads and utility corridors do not cross any streams with defined channels.

The effects of the Project will be mitigated by design and by reclamation. The surface disturbances will be designed to discharge runoff into undisturbed vegetated areas, rather than to drain directly to existing channels. Reclamation activities will be initiated when feasible. Upon Project completion, the entire Project disturbance will be reclaimed and the landscape restored to be similar to the pre-existing conditions.

Water volumes from the stormwater ponds will be monitored to determine how much water is pumped into the natural environment.

VCI ATS Project Hydrology Assessment Project 17470, Sept 5, 2012 ii

CREDITS AND ACKNOWLEDGEMENTS

This project was carried out by Gary Van Der Vinne, M.Sc., P. Eng., Tony Ye, M. Eng., E.I.T., James Snyder, E.I.T. and Kerry Paslawski, C.E.T.. Climate data used in this report was obtained from Environment Canada’s National Climate Data and Information Archive. Streamflow data was obtained from Environment Canada’s Water Survey Canada Archived Hydrometric Data and the Regional Aquatics Monitoring Database. Mapping information was obtained from the National Topographic Service’s National Topographic Database (NTDB) and the AltaLIS digital mapping service. Digital elevation data was obtained from Geobase.

DISCLAIMER

This document has been prepared by Northwest Hydraulic Consultants in accordance with generally accepted engineering and geoscience practices and is intended for the exclusive use and benefit of the client for whom it was prepared and for the particular purpose for which it was prepared. No other warranty, expressed or implied, is made.

Northwest Hydraulic Consultants and its officers, directors, employees, and agents assume no responsibility for the reliance upon this document or any of its contents by any party other than the client for whom the document was prepared. The contents of this document are not to be relied upon or used, in whole or in part, by or for the benefit of others without specific written authorization from Northwest Hydraulic Consultants and our client.

VCI ATS Project Hydrology Assessment Project 17470, Sept 5, 2012 iii

TABLE OF CONTENTS 1 Introduction .................................................................................................................. 1

2 Terms of Reference ...................................................................................................... 2

3 Assessment Method .................................................................................................... 3

3.1 Location and Spatial Boundaries ............................................................................. 3 3.1.1 Regional Study Area ........................................................................................ 3 3.1.2 Local Study Area .............................................................................................. 3 3.1.3 Project Footprint ............................................................................................... 4

3.2 Temporal Boundaries .............................................................................................. 4 3.3 Assessment Criteria ................................................................................................ 5

4 Regional Climate .......................................................................................................... 6

4.1 Air Temperature ...................................................................................................... 6 4.2 Precipitation ............................................................................................................ 6 4.3 Evaporation ............................................................................................................. 8

5 Regional Hydrology ................................................................................................... 10

5.1 Flow Characteristics .............................................................................................. 10 5.2 Runoff Coefficients ................................................................................................ 10 5.3 Mean Flows ........................................................................................................... 11 5.4 Extreme Flows ...................................................................................................... 13

6 Local Hydrology ......................................................................................................... 14

6.1 Local Hydrography ................................................................................................ 14 6.2 Local Channel Characteristics ............................................................................... 14 6.3 Local Snow Course Data ....................................................................................... 15 6.4 Local Extreme Flows ............................................................................................. 15

7 Baseline Case ............................................................................................................. 17

7.1 Existing Water Rights ............................................................................................ 17 7.2 Footprint of Existing and Approved Developments ................................................ 17

7.2.1 Surface Disturbances ..................................................................................... 17 7.2.2 Stream Disturbances ...................................................................................... 19

7.3 Hydrologic Impacts from Baseline Case ................................................................ 19 7.3.1 Runoff Volumes and Streamflows .................................................................. 19 7.3.2 Water Levels and Surface Areas .................................................................... 21 7.3.3 Channel Morphology and Sediment Concentrations ....................................... 21

8 Application Case ........................................................................................................ 22

8.1 Project Footprint .................................................................................................... 22 8.1.1 Surface Disturbances ..................................................................................... 22

VCI ATS Project Hydrology Assessment Project 17470, Sept 5, 2012 iv

8.1.2 Stream Disturbances ...................................................................................... 24 8.1.3 Water Supply ................................................................................................. 24

8.2 Potential Hydrologic Impacts ................................................................................. 25 8.2.1 Runoff Volumes and Streamflows .................................................................. 25 8.2.2 Water Levels and Surface Areas .................................................................... 27 8.2.3 Channel Morphology and Sediment Concentrations ....................................... 28

9 Planned Development Case ...................................................................................... 30

10 Mitigation and Monitoring .......................................................................................... 30

10.1 Mitigation .............................................................................................................. 30 10.2 Monitoring ............................................................................................................. 31

11 Summary of Conclusions .......................................................................................... 32

11.1 Baseline Case ....................................................................................................... 32 11.2 Application Case ................................................................................................... 33 11.3 Planned Development Case .................................................................................. 33 11.4 Mitigation and Monitoring ...................................................................................... 33

12 References .................................................................................................................. 35

VCI ATS Project Hydrology Assessment Project 17470, Sept 5, 2012 v

LIST OF TABLES

Table 1 Summary of monthly temperature and precipitation characteristics for the climate normal period from 1971 to 2000 at Fort McMurray Airport ............... 7

Table 2 Rainfall intensity-duration-frequency statistics for Fort McMurray .................. 8

Table 3 Summary of WSC gauges in the region .......................................................11

Table 4 Summary of runoff coefficients and mean flows ...........................................12

Table 5 Summary of extreme flows for the WSC gauges in the region ......................13

Table 6 Summary of flow measurements at the monitoring site on main stem of tributary in Drainage Basin A ........................................................................15

Table 7 Summary of drainage areas and estimated flows for local watersheds .........16

Table 8 Summary of existing disturbance areas within RSA .....................................18

Table 9 Summary of changes in runoff volumes due to existing and approved disturbances .................................................................................................20

Table 10 Summary of Project Components .................................................................23

Table 11 Summary of stormwater pond volumes and peak flows from CPF areas ......26

Table 12 Summary of changes in runoff volumes and streamflows for Application Case .....................................................................................................................27

Table 13 Summary of impact rating on surface water hydrology valued environmental components (VECs) .....................................................................................29

VCI ATS Project Hydrology Assessment Project 17470, Sept 5, 2012 vi

LIST OF FIGURES

Figure 1 Project and station locations

Figure 2 Regional study area

Figure 3 Local study area

Figure 4 Monthly air temperatures

Figure 5 Annual precipitation and winter snowfall

Figure 6 Monthly precipitation

Figure 7 Monthly evaporation and evapotranspiration

Figure 8 Variation of discharge with drainage area

Figure 9 Regional flow frequency distributions

Figure 10 Local hydrography

Figure 11 Channel characteristics at the hydrology monitoring site

Figure 12 Baseline disturbance conditions

Figure 13 Project layout

Figure 14 Drainage of Project development

VCI ATS Project Hydrology Assessment Project 17470, Sept 5, 2012 1

1 Introduction

Value Creation Inc. (VCI) is proposing its Advanced TriStar Project (ATS Project) on VCI’s TriStar leases, which are located in the Regional Municipality of Wood Buffalo. The ATS Project will be developed on an 11 section lease located about 10 km northeast of Fort McMurray (Figure 1). The ATS Project will be implemented as three phases that will increase the reservoir bitumen production from an initial 15,000 barrels per day (bpd) with ATS-1, to 45,000 bpd with ATS-2, and finally to 75,000 bpd with ATS-3.

This report provides a summary of the baseline hydrologic characteristics in the vicinity of the ATS Project, and addresses the impacts of the existing developments and proposed ATS Project on the surface water hydrology. Included in this evaluation is an assessment of the regional meteorological and hydrologic characteristics, the local hydrography, a brief description of the development plan, and an assessment of the impacts of the development on the streamflows, water levels and channel characteristics of the affected watersheds.


2 Terms of Reference

This surface water hydrology assessment was conducted according to the final Terms of Reference (TOR) issued by Alberta Environment and Sustainable Resource Development (AESRD). The specific requirements for surface water hydrology are as follows:

“3.3.1 Baseline Information [A] Describe and map the surface hydrology in the Project Area.

[B] Identify any surface water users who have existing approvals, permits or licenses.

3.3.2 Impact Assessment [A] Describe the extent of hydrological changes that will result from disturbances to groundwater and surface water movement:

a) include changes to the quantity of surface flow, water levels and channel regime in watercourses (i.e., during minimum, average and peak flows) and water levels in waterbodies;

b) assess the potential impact of any alterations in flow on the hydrology and identify all temporary and permanent alterations, channel realignments, disturbances or surface water withdrawals;

c) discuss the effect of these changes on hydrology (e.g., timing, volume, peak and minimum flow rates, river regime and lake levels), including the significance of effects for downstream watercourses; and

d) identify any potential erosion problems in watercourses resulting from the Project.

[B] Describe impacts on other surface water users resulting from the Project. Identify any potential water use conflicts.

[C] Discuss the impact of low flow conditions and in-stream flow needs on water supply and water and wastewater management strategies.”

The effects of the Project on groundwater movement are discussed in the Hydrogeology Environmental Assessment (MEMS, 2012).


3 Assessment Method

3.1 LOCATION AND SPATIAL BOUNDARIES

The proposed ATS Project is located in the Clearwater River watershed, on the north side of the Clearwater River. Its legal location is Section 20 to 30, Township 89, Range 8, West of the 4th Meridian. Figure 1 shows the location of the Project and the relevant climate and hydrometric stations in north-eastern Alberta.

The Project lies within the Central Mixedwood subregion of the Boreal Forest of northern Alberta. This low-relief plain is relatively poorly drained. Organic soils are dominant in the region. Well drained areas consist of mixed-wood forests of deciduous and coniferous species. The most abundant trees are trembling aspen and balsam poplar with white spruce, black spruce, and balsam fir also occurring. Poorly drained areas consist of wetlands including bogs, fens, swamps and marshes which contain tamarack and black spruce.

The spatial boundaries considered for the Surface Water Hydrology Assessment include the:

• Regional Study Area (RSA);

• Local Study Area (LSA); and

• Project Footprint.

3.1.1 REGIONAL STUDY AREA

The Hydrology RSA is defined as the area in which flows and water levels could be affected directly or indirectly by the Project. The boundary of the RSA is shown in Figure 2. With a total area of 75.0 km2, the RSA consists of Drainage Basin A draining west into the Clearwater River. The RSA is limited to this drainage basin because potential impacts to the Clearwater River downstream of the drainage basin are anticipated to be negligible due to the much larger drainage area of the River.

3.1.2 LOCAL STUDY AREA

The Hydrology LSA is defined as the Project Footprint and surrounding areas which would be directly affected by runoff from the Project. The boundary of the LSA is shown in Figure 3 along with the boundaries of the smaller scale watersheds A1 to A5 within the LSA. The LSA covers an area of about 57.5 km2. The LSA is limited within this boundary because no direct impacts to the main stem of the tributary which lies within Drainage Basin A downstream of the LSA are anticipated.


3.1.3 PROJECT FOOTPRINT

The Project Footprint for surface water hydrology is defined as the area of direct disturbance provided by VCI with a total of 406 ha. The Project Footprint is shown in Figure 2 and Figure 3. Elevations within the Project Footprint vary from 380 to 440 m.

3.2 TEMPORAL BOUNDARIES

The temporal boundary for the surface water hydrology assessment was defined by the life span of the Project. The Project will be constructed and operated in a series of phases. However, the assessment considers either that the entire Project is undeveloped or developed. This results in a conservative evaluation so that effects are not underestimated. Construction is scheduled to commence in 2014 with an anticipated operational start date two years later in 2016. The operational phase of the Project is 25 years. Based on this scenario, the operational phase of the Project would extend from 2016 to 2041 with decommissioning commencing in 2040 decade.

Three assessment scenarios were considered: Baseline Case; Application Case; and Planned Development Case. The Baseline Case is defined as existing and approved developments in the LSA as of March 2012. The Application Case is defined as the proposed Project disturbances in addition to the Baseline Case, assuming that all phases of the Project are constructed and operational at the same time. The Planned Development Case includes the assessment of all projects in the Baseline and Application Cases and all reasonably foreseeable projects in the LSA. Hydrologic conditions defined by a regional hydrologic analysis were used as the basis of comparison for the assessment of these scenarios.


3.3 ASSESSMENT CRITERIA

Valued environmental components (VECs) of the surface water hydrology were identified and the residual effects of the Project on these VECs after mitigation were assessed according to the following criteria:

• Type of Effect: Application; Cumulative • Geographical Extent: Local, Regional, Provincial, National, Global • Duration: Short, Long, Extended, Residual • Frequency: Continuous, Isolated, Periodic, Occasional • Reversibility: Short term, Long term, Irreversible • Magnitude: Nil, Low, Moderate, High • Project Contribution: Neutral, Positive, Negative • Confidence Rating: Low, Medium, High • Probability of Occurrence: Low, Median, High • Impact Rating: No Impact, Low, Moderate, High

Potential residual effects on hydrology were assessed quantitatively wherever feasible. Qualitative assessments and professional judgment were incorporated where necessary.

The following list of VECs was included in the hydrology assessment:

• runoff volumes and streamflows

• water levels and surface areas

• channel morphology and sediment concentrations


4 Regional Climate

Climate influences many hydrologic characteristics. Over the long term, the climate and local surficial geology determine the vegetation in the area. Surficial geology and vegetation affect the runoff coefficients and evapotranspiration rates in the area. On a shorter time scale, the magnitude of the winter snowpack and severity of summer rain events affect the severity of spring and summer runoff events.

Environment Canada (EC) provides climate data for a station in the vicinity of the Project. The climate station is located at Fort McMurray Airport (3062693) about 10 km south of the Project (Figure 1) at an elevation of 369 m, which is somewhat lower than the mean elevation in the LSA of 400 m. This station provides a long term continuous climate record for the area, reporting measurements as far back as 1944. This station reports air temperatures and precipitation, as well as rainfall intensity, wind speed and direction, atmospheric pressure, hours of bright sunshine, and humidity.

4.1 AIR TEMPERATURE

Air temperature is an important climatic variable in the hydrologic cycle because it determines the relative proportion of rain and snow within the total annual precipitation and the start and severity of snowmelt runoff in the spring. The average daily maximum, mean, and minimum temperatures for each month at Fort McMurray Airport for the climate normal period between 1971 and 2000 are summarized in Table 1. The monthly mean temperatures are also shown in Figure 4. The monthly mean temperature ranges from 17°C in July to -19°C in January. The average daily maximum and minimum temperatures for each month range from 23°C in July to -24°C in January. The mean daily air temperature drops below freezing in November and rises above freezing in April.

4.2 PRECIPITATION

Precipitation is the most important climate variable that affects the hydrologic cycle. Winter snowfall influences the magnitude and duration of the spring snowmelt flows, while summer rain events produce summer peak flows. Precipitation from previous events also affects the amount of runoff from a rainfall event.

The variations in annual precipitation (Nov-Oct) for Fort McMurray Airport are shown in Figure 5. The maximum annual precipitation of 683 mm occurred in 1973, while the minimum annual precipitation of 238 mm occurred in 1998.The mean annual precipitation for this entire 1945-2011 precipitation record is 437 mm, which is slightly less than the mean annual precipitation of 456 mm for the climate normal period from 1971-2000.


Table 1 Summary of monthly temperature and precipitation characteristics for the climate normal period from 1971 to 2000 at Fort McMurray Airport

Month Average Daily

Maximum Temperature

(°C)

Monthly Mean

Temperature (°C)

Average Daily

Minimum Temperature

(°C)

Monthly Mean

Precipitation (mm)

Daily Extreme

Precipitation (mm)

January -14 -19 -24 19 16

February -8 -14 -20 15 13

March 0 -7 -13 16 30

April 10 3 -3 22 27

May 17 10 3 37 39

June 21 15 8 75 50

July 23 17 10 81 53

August 22 15 9 73 95

September 15 9 3 47 61

October 8 3 -2 30 29

November -4 -9 -13 22 16

December -12 -17 -21 19 23

Annual 1 456

The monthly mean precipitation for the climate normal period from 1971-2000 for Fort McMurray Airport are shown in Figure 6 and listed in Table 1. The greatest monthly precipitation of 81 mm occurs in July. Monthly precipitation in the vicinity of the Project is expected to be same as that of Fort McMurray Airport.

Generally, all of the precipitation between November and March falls as snow and is stored on the ground until April and May, when the snow melts and snowmelt runoff is produced. The variation in winter precipitation (November to April) is shown in Figure 5 along with the annual precipitation. The maximum of 228 mm (water equivalent) occurred 1951 and the minimum of 58 mm occurred in 1949. The average winter precipitation is 116 mm. The winter precipitation is relatively constant from month to month, averaging about 20 mm per month at Fort McMurray (Table 1).

Extreme daily precipitation data for Fort McMurray station for the climate normal period from 1971-2000 are also summarized in Table 1. The extreme daily precipitation of 95 mm occurred in August.


Rainfall intensity-duration statistics are also available for Fort McMurray Airport. The statistics are summarized in Table 2. The 100-year 24-hour rainfall of 93.5 mm is similar to the extreme daily precipitation for the station while the 10-year 24-hr rainfall of 63.4 mm is about two-thirds of this value.

Table 2 Rainfall intensity-duration-frequency statistics for Fort McMurray

Duration Rainfall (mm)

2-year 5-year 10-year 25-year 50-year 100-year

5 minutes 5.1 7.4 8.9 10.8 12.3 13.7

10 minutes 7.0 9.9 11.8 14.1 15.9 17.7

15 minute 8.3 11.7 14.0 16.8 18.9 21.0

30 minutes 10.6 15.3 18.4 22.4 25.3 28.3

1 hour 12.8 17.6 20.9 24.9 28.0 30.9

2 hour 16.6 22.7 26.8 31.9 35.8 39.5

6 hours 25.0 34.8 41.3 49.6 55.7 61.7

12 hours 31.7 44.8 53.5 64.4 72.5 80.6

24 hours 39.3 53.8 63.4 75.6 84.6 93.5

4.3 EVAPORATION

Evaporation causes lake levels and soil moisture levels to drop during the open water season. Evaporation can be measured by evaporation pans or estimated by changes in lake levels. Lake evaporation tends to be about 70% of the measured pan or potential evaporation due to the higher humidity over the lake, although this percentage varies substantially with location (Linsley, et al, 1982). Evaporation from small ponds may be higher than lake evaporation and may approach the potential evaporation measured by evaporation pans.

Lake evaporation can be calculated from consideration of air temperatures, solar radiation, atmospheric pressure, and humidity; however, the first two parameters are most significant, especially in shallow lakes. Alberta Environment (1999) calculated potential and lake evaporation for Fort McMurray from 1972 to 1995. The average annual lake evaporation of 578 mm for this period is about 70% of the average annual potential evaporation of 823 mm for the same period.


Evapotranspiration, the combination of evaporation and transpiration from vegetated land, tends to be lower than lake evaporation due to the limitation of soil moisture availability. The median annual evapotranspiration for Fort McMurray is estimated to be about 288 mm (Alberta Environment, 1999), which is about 50% of the lake evaporation. Figure 7 shows the mean evaporation and evapotranspiration for each month. The majority of evaporation occurs from May to August, with the highest evaporation rates occurring in July.


5 Regional Hydrology

Evaluating the magnitude and variability of stream flows is a major component of a hydrologic assessment. The evaluation of streamflow includes an analysis of runoff coefficients and extreme flows in the region and an assessment of the local hydrography and channel characteristics.

5.1 FLOW CHARACTERISTICS

Water Survey of Canada (WSC) maintains a number of streamflow gauges in the region. The locations of these gauges are shown in Figure 1 and a summary of their characteristics is given in Table 3. The gauges provide a record of discharges for streams with drainage areas ranging from 54 km2 for the Robert Creek River near Anzac (07CE004) to 5990 km2 for the Firebag River near the mouth (07DC001). The period of record begins in 1965. Nine of the gauges listed in Table 3 are currently operated seasonally from March to October with discharge data published to the end of 2010 or 2011. Most of the gauges were operated annually for a period of time before being operated seasonally, so there are some historical winter flow data available.

Flow data available from the Regional Aquatics Monitoring Program (RAMP) database was used to supplement flow records for the Ells River. Flow data from other RAMP gauges were not of sufficient duration to be considered in the regional analysis.

5.2 RUNOFF COEFFICIENTS

Annual runoff coefficients define the fraction of annual precipitation which leaves the watershed as streamflow each year. Annual precipitation was calculated from November to October each year to associate the accumulated winter snowfall with the runoff in the following spring and summer.

Runoff coefficients were calculated from the streamflow records for the gauges listed in Table 4. To provide a meaningful comparison of runoff from the various watersheds, the seasonal runoff for each watershed was calculated from the streamflow for the period from March to October, since winter flow data is only available for portions of the periods of record at most of the gauges. When winter streamflow data was available, it was generally about 6% of the total annual flow so the real annual runoff coefficients may be up to 6% greater than the values provided in Table 5. The median mean seasonal runoff coefficient for the region is 0.20.


Table 3 Summary of WSC gauges in the region Stream Location Gauge Number Gauge Type Period of

Record Drainage

Area (km2)

Robert Creek Anzac 07CE004 Seasonal 1982-1995 54.1

Beaver River Syncrude 07DA018 Continuous Seasonal

1975-1987 1988-2010 165

Joslyn Creek Fort McKay 07DA016 Continuous Seasonal

1975-1981 1982-1993 257

Unnamed Creek Fort McKay 07DA011 Continuous

Seasonal 1975-1981 1982-1993 274

Pony Creek Chard 07CE003 Seasonal 1982-2010 279

Hartley Creek Fort McKay 07DA009 Continuous Seasonal

1975-1987 1988-1993 358

House River Hwy 63 07CB002 Seasonal 1982-2010 781

Hangingstone River

Fort McMurray 07CD004 Continuous

Seasonal 1970-1987 1965-2010 797

MacKay River

Dunkirk River 07DB005 Seasonal 1983-1991 1010

Steepbank River

Fort McMurray 07DA006 Continuous

Seasonal 1972-1986 1987-2011 1320

Muskeg River Fort McKay 07DA008 Continuous Seasonal

1974-1986 1987-2011 1460

Ells River Mouth 07DA017 S14 & S14A1

Continuous Seasonal

1975-1986 2001-2011 2450

Christina River Chard 07CE002 Seasonal 1982-2010 4860

MacKay River Fort McKay 07DB001 Continuous

Seasonal 1972-1987 1988-2010 5570

Firebag River Mouth 07DC001 Continuous Seasonal

1971-1987 1988-2011 5990

1 RAMP gauge

5.3 MEAN FLOWS

Mean seasonal flows calculated from the streamflow records for each of the WSC streamflow gauges are summarized in Table 4. The mean seasonal flow was calculated for the period from March to October, since winter flow data is only available for portions of the periods of records at most of the gauges. The mean flow ranged from 0.17 m3/s for Robert Creek near Anzac to 21.2 m3/s for Firebag River near the mouth. The trend shown in Figure 8 indicates that mean flow is directly proportional to drainage area.


Table 4 Summary of runoff coefficients and mean flows Stream Location Drainage

Area (km2)

Median Seasonal1

Runoff Coefficient

Mean Seasonal1

Flow (m3/s)

Mean Annual Peak Flow (m3/s)

Mean Minimum Monthly

Flow2 (m3/s)

Robert Creek Anzac 54.1 0.24 0.17 2.51 0.01

Beaver River Syncrude 165 0.21 0.49 9.42 0.05

Joslyn Creek Fort

McKay 257 0.13 0.62 13.90 0.01

Unnamed Creek

Fort McKay 274 0.10 0.39 5.79 0.06

Pony Creek Chard 279 0.19 0.81 8.90 0.04

Hartley Creek Fort McKay 358 0.22 1.00 8.46 0.01

House River Hwy 63 781 0.25 2.79 18.66 0.55

Hangingstone River

Fort McMurray 797 0.31 3.40 45.26 0.21

MacKay River

Dunkirk River 1010 0.12 2.46 20.97 0.04

Steepbank River

Fort McMurray 1320 0.27 4.65 37.09 0.38

Muskeg River Fort McKay 1460 0.19 3.73 26.13 0.36

Ells River Mouth 2450 0.21 6.38 55.36 0.74

Christina River

Chard 4860 0.19 13.98 81.60 3.07

MacKay River

Fort McKay 5570 0.16 13.63 120.27 0.43

Firebag River Mouth 5990 0.27 21.17 120.91 9.18 1 Seasonal data are for March to October. Annual flows are typically about 6% higher than seasonal amount. 2 Includes winter flows where available


The mean annual peak flows for the WSC gauges in the region are summarized in Table 5. The mean annual peak flows generally increase with drainage area (Figure 8), but smaller drainage areas produce higher mean annual peak flows relative to their drainage areas.

Average minimum monthly flows are listed in Table 4 for the WSC gauges in the region. These minimum flows include winter flows when available. Minimum flows typically occur during the winter months but can also occur during summer dry periods. The relationship of these minimum flows with drainage area is shown in Figure 8.

5.4 EXTREME FLOWS

Extreme flows from the historical records of the WSC gauges were evaluated. The peak flows for a range of return periods estimated using log-normal distribution are listed in Table 5. Flow frequency distributions of the annual peak flows from the gauges, normalized by mean annual peak flow, are shown in Figure 9. An adopted regional log-normal distribution is also shown in Figure 9.

Table 5 Summary of extreme flows for the WSC gauges in the region Stream Location Drainage

Area (km2)

Estimated Peak Flows (m3/s)

2-Yr 5-Yr 10-Yr 25-Yr 100-Yr

Robert Cr. Anzac 54.1 2.2 3.6 4.6 6.0 8.3 Beaver R. Syncrude 165 6.5 13.9 20.7 31.7 53.6 Joslyn Cr. Fort McKay 257 11.3 20.4 27.8 38.7 58.0

Unnamed Cr. Fort McKay 274 4.7 8.0 10.6 14.2 20.4 Pony Cr. Chard 279 7.3 12.4 16.3 21.9 31.3

Hartley Cr. Fort McKay 358 6.5 13.0 18.6 27.3 43.7 House R. Hwy 63 781 16.3 26.9 34.9 46.1 65.0

Hangingstone R. Ft McMurray 797 36.5 63.2 84.3 114.6 167.0 MacKay R. Dunkirk R. 1010 15.4 32.4 47.9 72.5 120.5

Steepbank R. Ft McMurray 1320 31.8 52.2 67.6 89.2 125.3 Muskeg R. Fort McKay 1460 22.1 37.3 49.1 65.8 94.2

Ells R. Mouth 2450 49.5 105.1 155.9 237.2 397.2 Christina R. Chard 4860 68.3 119.6 160.2 218.8 320.9 MacKay R. Fort McKay 5570 91.8 178.6 252.8 366.3 577.4 Firebag R Mouth 5990 112.2 156.0 185.3 222.6 278.9


6 Local Hydrology

6.1 LOCAL HYDROGRAPHY

The Project lies within the drainage basin of the Clearwater River (Figure 1). Most of the LSA is drained by small tributaries and undefined drainages which flow into the main stem of the tributary which lies within Drainage Basin A before it flows westerly into the Clearwater River. The LSA is subdivided into five small watersheds. The extents of these five watersheds are shown in Figure 10. These watersheds range in size from 3.9 km2 to 23.3 km2.

The mapped stream network in the vicinity of the lease was divided into streams with defined channels and drainages without defined channels (Figure 10). Observations in the region indicate that the stream network obtained from 1:50,000 scale National Topographic Service (NTS) maps provides a reasonable indication of where streams with defined channels occur. The streams with defined channels shown in Figure 10 were derived from NTS maps with some minor modifications to maintain consistency with Digital Elevation Model (DEM) data obtained from the Geobase database and with observations carried out by aerial reconnaissance. Additional hydrography obtained from 1:20,000 scale maps obtained from AltaLIS are shown on Figure 10 as drainages without defined channels.

There are no permanent lakes in the LSA or RSA; however, small beaver ponds exist on a number of the streams and drainages.

6.2 LOCAL CHANNEL CHARACTERISTICS

A hydrology monitoring site was established on the main stem of the tributary which lies within Drainage Basin A near a bridge crossing. The monitoring site was located downstream of the confluence where the tributary draining watershed A2 joins the main stem (Figure 11). The UTM position of the monitoring site is 481453E, 6287013N. The catchment area upstream of the monitoring site is 59.5 km2.

Water levels, widths, depths, and velocities were measured at the site to quantify the local flow characteristics during 2010-2011. Local elevations were referenced to a temporary benchmark at the site. Velocity measurements were carried out using an electromagnetic flow meter mounted on a wading rod. A summary of the flow characteristics observed at the site is given in Table 6. Discharges estimated from the site measurements ranged from 0.0018 m3/s to 0.063 m3/s. The measured discharges tend to be lower than average as defined by the regional relationship of mean annual flow versus drainage area in Figure 8. This is likely due to the lower-than-average precipitation in 2010-2011. The reported annual precipitation for Fort McMurray A was 326 mm in 2010 and 280 mm in 2011, which is lower than the mean annual precipitation of 433 mm.


Table 6 Summary of flow measurements at the monitoring site on main stem of tributary in Drainage Basin A

Date

Wetted Width

(m)

Mean Velocity

(m/s)

Discharge (m3/s)

Water Level (m)

2010-09-22 3.45 0.050 0.0629 98.667

2011-06-14 2.50 0.014 0.0132 98.601

2011-08-23 1.25 0.015 0.0018 98.585

2011-09-20 1.10 0.019 0.0021 98.568

A water level recorder was installed at the site which recorded hourly water level fluctuations from September 2010 to September 2011. These water level records were transformed to discharge records using the flow measurement listed in Table 6. The water level and discharge records for the site are shown in Figure 11 along with cross sections and photographs of the sites. As shown in Figure 8, the estimated peak flow of 0.225 m3/s is below the average established from the regional analysis.

6.3 LOCAL SNOW COURSE DATA

Snow depths and densities were also measured on March 8, 2011 near the site. The snow measurements were taken at approximate 50 m intervals over a 500 m long line about 150 m north of the winter road. The average snow depth was 0.45 m and the average water equivalent was 84 mm. This was greater than the accumulated precipitation for the winter period of 47.5 mm reported at Fort McMurray Airport.

6.4 LOCAL EXTREME FLOWS

Table 7 summarizes the estimated hydrologic characteristics of the local watersheds. The mean annual and annual minimum monthly flows were estimated on the basis of the regional relationships shown in Figure 8. The log-normal distribution adopted for the regional flood frequency analysis shown in Figure 9 was used to estimate the expected flood peaks for each watershed.


Table 7 Summary of drainage areas and estimated flows for local watersheds

Watershed

Location Drainage Area (km2)

Mean Annual Flow

(m3/s)

Mean Annual Peak Flow

(m3/s)

10-Year Peak Flow (m3/s)



Average Minimum Monthly

Flow (m3/s)

A1 Mouth 3.91 0.012 0.32 0.71 1.03 1.64 0.00019 A2 Mouth 13.13 0.039 0.84 1.87 2.73 4.34 0.00087

A3 Mouth 12.34 0.037 0.80 1.78 2.60 4.13 0.00080 A4 Mouth 4.86 0.015 0.38 0.84 1.23 1.96 0.00025

A5 Mouth 23.29 0.070 1.33 2.96 4.32 6.88 0.00180 A Monitoring site 59.49 0.178 2.82 6.29 9.18 14.60 0.00592

A Mouth 75.02 0.225 3.40 7.58 11.06 17.59 0.00794

A Hydrologic Simulation Program – FORTRAN (HSPF) model was developed to simulate local flow conditions. The HSPF model simulates watershed runoff processes including winter snow accumulation, snowmelt, summer runoff, evaporation and evapotranspiration on a continuous basis, with precipitation, potential evaporation, and temperature as the main inputs. At first, the model was calibrated to simulate the Water Survey Canada recorded flow for Beaver River above Syncrude for years 1975 through 2010, as it represents the typical long term flows in the region with a watershed area similar to the area of Drainage Basin A. Precipitation, temperature and potential evaporation inputs were based on the data from Fort McMurray. The model was configured to run at a one hour time step for the period 1961 through 2011. The first two years were used to initialize drainage watershed moisture conditions and the results for these two years were excluded from subsequent analyses. The model was then adjusted to represent the characteristics of the watersheds in the LSA as represented by local flow measurements.

The model was used in the following sections to perform a more detailed process-based assessment of the hydrologic effects of development.


7 Baseline Case

This section describes the hydrologic impacts of the existing and approved developments in the LSA.

7.1 EXISTING WATER RIGHTS

According to Alberta Environment’s Water Rights database, there are no surface water users who have existing approvals, permit or licenses within the LSA.

7.2 FOOTPRINT OF EXISTING AND APPROVED DEVELOPMENTS

To evaluate the total effects on the drainage in the local watershed watersheds, existing and approved disturbances were considered including:

• a pipeline corridor,

• a winter road,

• seismic cutlines, and

• Oil Sands Exploration (OSE) well pads

For convenience, all disturbances within the RSA were considered. The locations of these disturbances are shown in Figure 12.

7.2.1 SURFACE DISTURBANCES

Existing surface disturbances within the RSA include 45.9 ha of pipeline, 31.0 ha of seismic cutlines, 9.3 ha of OSE well pads, and 4.9 ha of winter road. Table 8 summarizes the extent of the spatial disturbances within the individual drainage watersheds. The total disturbed area in the RSA is 91.0 ha, which is 1.2% of the total area of RSA. The most disturbed watershed is A5, with 2.5% of the area disturbed, largely because the pipeline lies within A5.

Pipeline

A major pipeline line in the eastern part of Watershed A5 has total disturbance area of 45.9 ha. The surface of the pipeline area will be non-forested vegetation and no soil compaction is expected. A runoff coefficient of 0.30 is estimated for this type of area relative to the undisturbed runoff coefficient of 0.20.


Table 8 Summary of existing disturbance areas within RSA Watershed Pipeline

(ha) Seismic Cutlines

(ha)

OSE Well Pad (ha)

Winter Road (ha)

Total Disturbed

area (ha)

Total Watershed

Area (ha)

Percentage of

Watershed Disturbed

(%) A1 0.0 4.4 2.0 0.0 6.4 391.4 1.64%

A2 0.0 4.6 0.6 3.8 9.0 1312.6 0.68%

A3 0.0 4.7 0.7 0.5 6.0 1234.4 0.49%

A4 0.0 0.4 0.0 0.0 0.4 486.4 0.08%

A5 45.9 10.0 1.2 0.0 57.1 2329.3 2.45%

A Upstream of Site 0.0 1.1 0.0 0.0 1.1 586.1 0.20%

A Downstream of Site 0.0 5.8 4.7 0.5 11.0 1162.3 0.94%

Grand Total 45.9 31.0 9.3 4.9 91.0 7502.4 1.21%

Winter Road

There is one existing winter road located mainly in A2 and A3. The total area of the winter road is 4.9 ha. There is no gravel on the surface of the road but soil compaction was observed. The runoff coefficient from the soil-compacted road surfaces is expected to about 0.40. The runoff from the road surface will flow into the ditches where some of the runoff will be stored. The remaining surface of the winter road will be non-forested vegetation with a runoff coefficient of about of 0.25. Thus, an effective runoff coefficient of 0.35 is estimated for the winter road.

Seismic Cutlines

There are 31.0 ha of seismic cutlines distributed in all watersheds. These cutlines are temporary use only and will not be maintained after the seismic exploration activity is finished. Soil compaction is not expected. As such, a runoff coefficient of 0.25 is adopted for these cutlines to represent the long term re-vegetating condition.

OSE Well Pads

As shown in Figure 12, OSE well pads are distributed sparsely in most of the watersheds. The total area of these OSE well pads are 9.3 ha. The well pads are constructed during winter with no soil compaction. The pad area is non-forested vegetation during the temporary operation period. Their runoff coefficient is believed to be about 0.25, given that the nature of these well pads will be the same as seismic cutlines in long term. The water quality of the runoff from the well pads is not expected to be substantially different from the runoff from the undisturbed area.


7.2.2 STREAM DISTURBANCES

The winter road crosses the main stem of the tributary near the monitoring site and also crosses a number of mapped drainages. Other surface disturbances are located where they do not disturb any identified streams with defined channels. Locations of these crossings are shown in Figure 12.

7.3 HYDROLOGIC IMPACTS FROM BASELINE CASE

Existing and approved local development in the RSA may affect the hydrology as defined by the regional analysis presented in Section 6. The effects of this development on the hydrology VECs defined in Section 3.3 are evaluated in the following sections.

7.3.1 RUNOFF VOLUMES AND STREAMFLOWS

Existing and approved surface disturbances can cause changes to surface runoff characteristics of the natural environment. Specifically, changes in surface drainage patterns and changes in the runoff coefficients can affect the runoff volumes, peak flow rates, and timing of peak flows in the local streams. Water levels in ponds and wetlands may also be affected.

There are no significant changes in the surface drainage patterns due to existing and approved disturbances. There are no effects on water levels in wetlands since drainage patterns to wetlands were maintained.

The effect of existing and approved disturbances on runoff volumes in each individual watershed depends on the proportions of the watershed that were disturbed for development of pipelines, well pads, seismic cutlines and winter roads, which will tend to increase both runoff volumes and flood peaks due to the reduction in vegetation and the addition of less permeable surfaces.

Changes in runoff volumes were estimated assuming a worst case condition of the disturbed areas being directly connected to the drainage networks in the watersheds and that the estimated runoff coefficients for each disturbance type are applicable for all runoff events. These changes in runoff volumes are summarized in Table 9.


Table 9 Summary of changes in runoff volumes due to existing and approved disturbances

Watershed Total Drainage

Area (ha)

Total Disturbed

Area (ha)

Worst Case

Change in Runoff Volume

(%)

Average Change

in Runoff Volume

(%)

Average Change in 2-Year

Peak Flow (%)

Average Change in 2-Year Minimum

Flow (%)

A1 391.4 6.4 0.41% 0.38% 0.25% 2.7%

A2 1312.6 9.0 0.32% 0.32% 0.17% 1.2%

A3 1234.4 6.0 0.14% 0.15% 0.09% 0.5%

A4 486.4 0.4 0.02% 0.07% 0.02% 0.4%

A5 2329.3 57.1 1.11% 1.0% 0.57% 3.5%

A at monitoring site 5948.8 73.6 0.54% 0.5% 0.32% 1.8%

A Total 7502.4 91.0 0.49% 0.4% 0.31% 1.7%

The greatest worst case change in runoff volume occurs in Watershed A5, which is estimated to have an increase in runoff volume of about 1.11% due to the major pipeline lies in the watershed. Generally the worst case change in runoff volume in the Project RSA is estimated to be an increase up to 0.5% due to the seismic cutlines, winter road and OSE well pads.

HSPF modeling was used to perform a more detailed process-based assessment of the hydrologic effects of existing and approved disturbances. The HSPF model was modified to represent watershed alterations due to these disturbances. For most types of disturbances, the HSPF runoff parameters were adjusted to reflect the effects of clearing and soil compaction. The effects of clearing were simulated using a 25% reduction in potential evapotranspiration for cleared-but-vegetated areas such as pipelines, and ditches of the winter road. An additional 75% reduction in soil storage capacity was assumed to represent the effects of soil compaction for soil-compacted roads and OSE well pads. Seismic cutlines were simulated using a 15% reduction in potential evapotranspiration, reflecting their re-vegetating state.

HSPF simulations were carried out for all local watersheds and changes to runoff volumes, peak flows and minimum flows were assessed. The results of these assessments are summarized in Table 9.


The effects on runoff volumes were greatest for Watershed A5 with an overall average increase of 1.0%. Runoff volume increases were less apparent in wet years but more noticeable in dry years. The change in magnitude in 2-year peak flow was also greatest in Watershed A5, with a predicted increase of 0.57%. There were no perceptible changes in the timing of peak flows. Changes in magnitude of annual minimum flow rates appear to be large in some of the watersheds because they are relative to very small flows. In most of the watersheds the net effect will be less years with zero flow.

7.3.2 WATER LEVELS AND SURFACE AREAS

Annual peak water levels and surface areas in the streams are not anticipated to be affected by existing and approved disturbances since changes to snowmelt-dominated annual peak flows are expected to be small. Stream minimum water levels and surface areas may be slightly higher due to increased minimum flows; however, zero flows will still occur in most of these small watersheds.

Levels in small waterbodies created by beaver dams are controlled by the height of the beaver dams rather than by inflow volumes therefore small changes in streamflows are not expected to affect the water levels and surface areas of these features.

7.3.3 CHANNEL MORPHOLOGY AND SEDIMENT CONCENTRATIONS

Sediment concentrations in streams have the potential to increase due to increases in streamflow or from sediment introduced to the stream from disturbances. Sediment concentrations in the streams in the RSA do not appear to have increased due to changes in the surface runoff characteristics. The changes in the flow regime due to existing and approved disturbances are very small in most cases and would not have a perceptible effect on sediment concentrations.


8 Application Case

This section describes the assessment of potential hydrologic impacts of the combined footprint of the entire ATS Project on the local environment. The Project footprint is described, the potential effects identified and their severity assessed.

8.1 PROJECT FOOTPRINT

The Project will produce additional surface disturbances of approximately 406 ha. Figure 13 shows the layout of the Project. These developments are located in Township 89, Range 8, West of the 4th Meridian.

8.1.1 SURFACE DISTURBANCES

Surface disturbances for the Project include a central processing facility (CPF), well pads, borrow pits, utility and transportation corridors, and soil storage.

Table 10 summarizes the extent of the spatial disturbances for the Project Footprint in addition to the existing and approved disturbances within individual watersheds. The total disturbed area due to the Project is 405.99 ha, which is 5.4% of the total area of the RSA. The greatest percentage area of disturbance due to the Project will be 18.2% in Watershed A4.

Central Processing Facility

The proposed Central Processing facility (CPF) will be located in north half of Section 23, Township 89, Range 8, W4M (Figure13). The CPF will have a total area of 55.5 ha, of which 43 ha will be in Watershed A5 and 12.5 ha will be in Watershed A4. A runoff coefficient value of 0.6 is adopted for the CPF. The runoff from the CPF may be different in quality than the runoff from natural areas. It will be collected and stored in stormwater ponds as described in Section 9.2.1. The water will be used for the process or be discharged if the water quality is within parameters specified in the Environmental Protection and Enhancement Act approval (Hatfield Consultants, 2012). The water will be tested and released slowly and well after the surrounding natural runoff. As such, much of the water will be lost to evaporation and infiltration. It was assumed in the assessment that the stormwater ponds will be discharged proportionally into Watershed A4 and A5 based on the CPF area in each watershed.


Table 10 Summary of Project Components

Land Type A1 A2 A3 A4 A5 A at

monitor site A Total Project Footprint (ha) CPF 12.5 43.0 55.5 55.5 Borrow Pit 15.9 4.5 22.8 5.3 48.5 48.5 Subsoil Storage 0.5 2.8 2.1 9.1 14.6 14.6 Topsoil Storage 5.5 3.7 8.9 6.8 25.0 25.0 Utility Corridor 42.8 34.9 20.9 17.4 115.9 115.9 Well Pad 2.2 40.0 45.0 21.4 37.9 144.3 146.5 Subtotal 2.2 104.7 90.9 88.7 119.5 403.8 406.0 Baseline Case (ha) Pipeline 45.9 45.9 45.9 Seismic Cutlines 4.4 3.9 4.2 0.2 9.8 19.3 29.4 OSE Well Pad 2.0 0.2 0.7 1.2 2.2 8.9 Winter Road 3.5 0.5 4.1 4.6 Natural 382.8 1200.3 1138.0 397.5 2152.8 5473.6 7007.6 Total 391.4 1312.6 1234.4 486.4 2329.3 5948.8 7502.4

Note: All overlapped areas were removed from Baseline Case.

Borrow Pits

As shown in Figure 13, borrow pits will be distributed in Watersheds A2 to A5. These borrow pits will be used for construction material. The total disturbance area for the borrow pits will be 48.5 ha. Water collected in the borrow pits will either evaporate or seep into the ground. No runoff will be generated from these areas.

Soil/Sub-soil Storage

Soil and sub-soil storage areas are distributed through Watershed A2 to A5. (Figure 13). The total area used for soil storage is 39.6 ha. These areas are used to store soil for future reclamation of the disturbed areas. The vegetated slopes of the soil surfaces will be steeper than the undisturbed areas so the runoff coefficient for the soil storage areas is expected to be about 0.40.

Access Corridors

The access corridors will consist of access roads and utility corridors. The total area of the corridors is 115.9 ha (Figure 13). The runoff coefficient from the graveled road surfaces is expected to be about 0.60. The runoff from the road surface will be collected by ditches within the corridor. The remaining area of the access corridor will be non-forested vegetation


with a runoff coefficient of about 0.25. As such, the average runoff coefficient for the corridors is estimated as 0.40.

Well Pads

As shown in Figure 13, 35 well pads will be distributed over the drainage watersheds. The total area of the well pads will be 146.5 ha. The well pads will be constructed of compacted clay fill with a gravel cap. The water quality of the runoff from the well pads is not expected to be substantially different from the runoff from undisturbed areas. The runoff coefficient for the well pads is expected to be about 0.60.

8.1.2 STREAM DISTURBANCES

The Project footprint will not cross streams with defined channels. This was confirmed by low-level aerial inspection and ground inspection of these locations.

There will be 12 crossings of mapped drainages where the drainage pathways will be maintained with adequately sized culverts. These crossings are not navigable because no defined channels are present. The locations of these crossings are shown in Figure 13.

Most of the disturbed areas have been located to avoid mapped watercourses, however, one of the proposed well pads and two of the borrow pits are located on a mapped drainage. These drainages are not navigable as no defined channels are present. These locations are shown in Figure 13. The drainage will be directed around the well pad or borrow pits and back to its original pathway.

Construction will be conducted using best management practices to minimize erosion and sedimentation of watercourses. These practices include the installation of silt fences, seeding of disturbed areas and the use of sediment traps in road ditches.

8.1.3 WATER SUPPLY

The Project will use groundwater sources to supply water. The use of groundwater is not expected to have a measureable effect on flows within the Clearwater River relative to the natural flow variability.

Runoff from the CPF will be collected in stormwater ponds. The runoff volume stored in the stormwater ponds contained on the CPF may be used for process water. The mean annual runoff volume from the plant site is estimated to be about 152,000 m3 (55.5 ha x 0.6 x 456 mm). This is the amount of runoff water which could potentially be diverted on an annual basis for process water if sufficient storage is available to capture the runoff when it occurs.

There are no currently active licenses for surface water withdrawals within the LSA.


8.2 POTENTIAL HYDROLOGIC IMPACTS

The Project may affect the hydrology as defined by the regional analysis presented in Section 6. The effects of the Project on the hydrology VECs defined in Section 3.3 are evaluated in the following sections. A summary of the Project effects on these VECs is presented in Table 13 at the end of this section.

8.2.1 RUNOFF VOLUMES AND STREAMFLOWS

Surface disturbances from the Project developments can cause changes to surface runoff characteristics of the natural environment. Changes in surface drainage patterns or changes in the runoff coefficient may affect the runoff volumes, flow rates, and timing of peak flows in the local streams. Water levels in the lake may also be affected. If these changes are significant, they may in turn produce changes in the channel regime of the local streams.

There will be no significant changes in the surface drainage patterns due to the Project. Existing drainage paths will be maintained. As shown in Figure 14, appropriate drainage will be provided at crossings of identified drainages and there will be no transfer of water from one watershed to another along ditches and road right-of-ways.

The effect of the Project on runoff volumes in each individual watershed depends on the proportions of the watershed area that are used for the CPF, borrow pit, soil storage, multi-use corridors and well pads. The borrow pits will reduce runoff volumes and flood peaks because water will not be released from these areas. Soil storage and multi-use corridors will increase both runoff volumes and flood peaks due to the reduction in vegetation and the addition of less permeable surfaces. The CPF and well pads will tend to reduce the flood peaks because of the detention of runoff.

Runoff from the process areas and remaining non-process areas will be collected in separate stormwater ponds that will be sized to hold the runoff from a 10-year 24-hour rainfall of 63.4 mm. The required pond volumes were calculated based on the drainage areas of each component, assuming a design runoff coefficient of 0.75 to provide a factor of safety of 1.25 over the expected runoff coefficient of 0.60. The area for the main access road to the CPF is not included, as runoff from this area will be diverted into natural drainage pathways in the same way as for the rest of the utility corridors. The following is a summary of the stormwater pond sizes:

• ATS-1: o Main (non-process area) stormwater pond: 11,964 m3 o Process area stormwater pond: 659 m3

• ATS-2: o Main (non-process area) stormwater pond: 3,418 m3


o Process area stormwater pond: 586 m3 • ATS-3:

o Main (non-process area) stormwater pond: 4,181 m3 o Process area stormwater pond: 586 m3

The stormwater pond sizes for the process area and the remaining non-process area for each phase are also listed in Table 11. The 10-year peak runoff flow rates listed in Table 11 were estimated using the rational method. The runoff from the process areas will not be discharged into the natural environment but will be treated and used as process water.

Table 11 Summary of stormwater pond volumes and peak flows from CPF areas

Phase ATS-1 ATS-2 ATS-3

Total Area (ha) 26.55 8.42 10.33 Process Area (ha) 1.39 1.23 1.23 Non-process Area (ha) 25.16 7.19 8.80 Process Area Pond Volume (m3) 659 586 586 Main Pond Volume (m3) 11964 3418 4181 10-year Peak Flow (m3/s) 2.1 0.56 0.67

Changes in runoff volumes when the Project is fully developed were estimated assuming a worst case condition of the disturbed areas being directly connected to the drainage network in the watersheds and that the estimated runoff coefficients for each disturbance type are applicable for all runoff events. These changes in runoff volumes are summarized Table 12. The development of the Project would generally result in increased runoff volumes. The greatest worst case change in runoff volume will occur in Watershed A4 with estimated increases of 15.8%; however, the worst case increase for the entire basin would only be 7.3%.

HSPF modeling was used to provide a more detailed assessment the hydrologic effects of the Application Case. Simulations for the Application Case incorporate the modifications for the Project disturbances in addition to the Baseline Case, assuming a maximum impact scenario with full development of all Project phases before any reclamation occurs. For most types of the Project disturbances, the HSPF runoff parameters were adjusted to reflect the effects of clearing and soil compaction. The effects of clearing were simulated using a 25% reduction in potential evapotranspiration in cleared-but-vegetated areas such as utility corridors. An additional 75% reduction in soil storage capacity was assumed where the land is compacted for gravel roads and well pads. Areas of excavated pits and sumps were assumed to be non-draining and were removed from the drainage contributing areas. After a runoff event it was assumed that the water from the non-process area would be stored in the main stormwater pond, and discharged into Watershed A4 and A5.


Table 12 Summary of changes in runoff volumes and streamflows for Application Case

Watershed Total Drainage

Area (ha)

Total Disturbed

Area (ha)

Worst Case Change in

Runoff Volume

(%)

Average Change in

Runoff Volume

(%)

Average Change in 2-Year

Peak Flow (%)

Average Change

in 2-Year Minimum

Flow (%)

A1 391.4 8.6 1.5% 1.0% 0.5% 3.7%

A2 1312.6 112.3 8.9% 5.4% 1.7% 24.1%

A3 1234.4 96.4 10.4% 6.5% 2.6% 26.6%

A4 486.4 88.9 15.8% 8.4% 0.5% 35.8%

A5 2329.3 176.5 9.3% 5.8% 2.6% 24.1%

A at monitoring site 5948.8 475.2 9.0% 5.2% 1.7% 13.4%

A Total 7502.4 494.8 7.3% 4.5% 1.5% 11.9%

Simulations were carried out for all local watersheds. Changes to runoff volumes, peak flows and minimum flows are summarized in Table 12. The effects for the Application Case on runoff volumes are greatest for Watershed A4 with an overall average increase of 8.4%. The increase in runoff volume for the entire basin would be about 4.5%. Runoff volume increases are less apparent in wet years but more noticeable in dry years.

The changes in magnitude in 2-year peak flow due to the Application Case range from a 0.5% increase in Watershed A1 to a 2.6% increase in Watershed A5. There are no perceptible changes in the timing of peak flows, based on the simulation results.

Increases in magnitude of annual minimum flow rates appear to be large in some of the watersheds because they are relative to very small flows. In most of the watersheds the net effect due to the Application Case will be less years with zero flow.

8.2.2 WATER LEVELS AND SURFACE AREAS

Annual peak water levels and surface areas in the streams may change slightly due to changes in annual peak flow. These changes will be imperceptible compared to natural variability. Minimum water levels and surface areas may be slightly higher due to increased minimum flows; however, zero flows will still occur in most of these small watersheds.


Levels in small waterbodies created by beaver dams are controlled by the height of the beaver dams rather than by inflow volumes therefore small changes in streamflows are not expected to affect the water levels and surface areas of these features.

8.2.3 CHANNEL MORPHOLOGY AND SEDIMENT CONCENTRATIONS

Sediment concentrations in streams have the potential to increase due to increases in streamflow or from sediment introduced to the stream from disturbances. Sediment concentrations in the streams in the RSA are not expected to increase due to changes in the surface runoff characteristics because in most cases the runoff increase is not significant. Even in watersheds where increases in runoff may occur, changes in the flow regime due to surface disturbances are very small and would not have a perceptible impact on the sediment concentrations.


Table 13 Summary of impact rating on surface water hydrology valued environmental components (VECs) VEC Nature of Potential

Impact or Effect Mitigation/

Protection Plan Type of

Impact or Effect

Geographical Extent

Duration Frequency Reversibility Magnitude5 Project Contribution

Confidence Rating

Probability of Occurrence

Impact Rating

1. Runoff Volumes and Streamflows

Changes to runoff volume, peak flows, and low flows

1) Maintain drainage around disturbed areas 2) Reclaim surface disturbances once no longer required 3) Discharge runoff into natural environment away from streams in accordance with EPEA Approval

Application Local Long-term Periodic Reversible in long term

Low Negative High High Low

Cumulative Local Long-term Periodic Reversible in long term


2. Water Levels and Surface Areas

Changes in water levels and surface area due to streamflow changes

1) Maintain drainage around disturbed areas 2) Reclaim surface disturbances once no longer required 3) Discharge runoff into natural environment away from streams in accordance with EPEA Approval





3. Channel Morphology and Sediment Concentration

Changes in channel shape and sediment concentration due to flow changes and crossing construction

1) Maintain drainage around disturbed areas 2) Reclaim surface disturbances once no longer required 3) Design and construct crossings to minimize impacts


Low Negative High Low Low


Low Negative High Low Low


9 Planned Development Case

There are no other planned developments within the hydrology RSA except for a north-south access road which might be located in or to the east of Watershed A5. No additional stream crossings are anticipated within the hydrology RSA and the effect of the additional surface disturbances on runoff volumes and peak flows is expected to have a low impact.

10 Mitigation and Monitoring

Mitigation will be carried out to reduce the impacts of the Project on the identified hydrological indicators and monitoring will be carried out to confirm that the impacts are within their anticipated ranges. The indicators identified for surface water hydrology are runoff volumes and streamflows; water levels and surface areas; and channel morphology and sediment concentrations.

10.1 MITIGATION

The following practices and procedures will be carried out to reduce the effects of the development on the surface water hydrology:

• Water will not be transferred from one watershed to another

• Appropriate drainage culverts will be provided at crossings of any identifiable drainage courses to maintain existing drainage patterns.

• Disturbances will be kept away from streams with defined channels.

• Sediment control will be utilized for construction activity where runoff may potentially flow directly into drainages.

• Runoff from well pads will not be discharged directly to drainages.

• Run-on from upstream of well pads and plant site will be directed around the disturbances and back into their original pathways.

• Surface disturbances will be reclaimed after they are no longer required.

The drainage pathways around the Project components shown in Figure 14 were developed by applying the above practices and procedures.


10.2 MONITORING

Impacts on runoff volumes and streamflows will be difficult to distinguish from natural variability so direct monitoring of streamflows is not necessary. However, the following monitoring should be carried out to ensure that the impacts on the surface water hydrology are low:

• Routine visual inspections should be carried out to ensure that the access road drainage culverts are working as intended to maintain the natural surface drainage patterns.

• Water volumes pumped from the CPF stormwater ponds into the natural environment should be recorded.

• The volume of any runoff water used for process water should be recorded.


11 Summary of Conclusions

A hydrologic assessment was carried out for the VCI ATS Project which evaluated physiography, climate, and streamflow characteristics in the vicinity of the Project, assessed the hydrological effects of the Project footprint, and recommended mitigation and monitoring strategies.

11.1 BASELINE CASE

The regional surface water hydrology for baseline development conditions was described and mapped. A regional analysis of historical climate data was carried out to describe the variation in temperature, precipitation and evaporation. A regional analysis of historical streamflows was carried out to describe flow regimes and peak flows in the region. Regional watersheds were mapped and drainage areas quantified.

Local water levels and streamflows were measured at the site from 2010 to 2011. Snow course measurements were also taken in early spring of 2011. Flow regimes were evaluated from the regional streamflow analysis and from the HSPF hydrologic model calibrated to regional data and verified with local streamflow measurements.

Existing and approved developments in the RSA were described and the effects of these developments on the hydrology were quantified. Effects were evaluated for runoff volumes and streamflows; water levels and surface areas; and channel morphology and sediment concentrations. Runoff volumes were found to increase the greatest in watershed A5 with an increase of 1.0% relative to conditions established from the regional hydrology. There is no perceptible change on the timing of runoff hydrographs. Peak flows tend to be higher with increases in 2-year peak flows of up to 0.6%. Minimum flows in summer months could be higher with increases in 2-year minimum flows of up to 3.5%. Percentage changes in magnitude of annual minimum flow rates appear to be large in some of the drainage watersheds because they are computed relative to very low flows. In most of the watersheds the net effect will be less years with zero flow.

The effects of existing and approved development on water levels and surface areas are imperceptible compared to natural variability.

Channel morphology and sediment concentrations have not changed due to existing and approved development because changes to the flow regime are small. The existing stream crossings do not appear to have caused any increases in sediment concentration or erosion.


11.2 APPLICATION CASE

The Application Case was described and the effects of the proposed development on the hydrology were quantified. The entire Project was assumed to be developed in combination with the existing development to assess the maximum effect on the hydrology. Effects relative to conditions established from the regional hydrology data were evaluated for runoff volumes and streamflows; water levels and surface areas; and channel morphology and sediment concentrations.

The effect of this development scenario on runoff volumes is expected to increase annual runoff by up to 4.5%. The change in magnitude in 2-year peak flow due to development may increase as much as 2.6% in some areas. Changes in the timing of peak flows simulated are imperceptible. Percentage changes in magnitude of annual minimum flow rates appear to be large in some of the drainage watersheds because they are computed relative to very low flows. The predicted changes in flows from these small tributaries will be imperceptible in the Clearwater River due to the much greater flows in the river.

The effect of the Application Case on water levels and surface areas will be imperceptible compared to natural variability.

Channel morphology and sediment concentrations will not change due to the Application Case because changes to the flow regime are small. The access corridor stream crossings will be designed to minimize the disturbance to the channels so sediment inputs are not anticipated to increase.

11.3 PLANNED DEVELOPMENT CASE

The cumulative impact of projects in the hydrology RSA was considered. As there are no other activities planned in the hydrology RSA, the impact rating is low.

11.4 MITIGATION AND MONITORING

The effects of the Project will be mitigated by design and reclamation. The surface disturbances will be designed to discharge runoff into the natural landscape rather than directly into the drainage network as was assumed in the impact assessment. Infiltration, depression storage and evapotranspiration will tend to buffer the effects of increased runoff from compacted soils. Drainage will be provided around the disturbances so that runoff patterns are maintained. In general impacts are expected to be less than what is predicted in this report because some areas will likely be reclaimed before other areas are developed so the maximum footprint will always be less than that of the total Project. As well, the hydrologic impacts presented in this report will be temporary as the entire Project


disturbance will be reclaimed to match the pre-existing conditions as closely as possible after the Project is complete.

Streamflow monitoring is not required because the effects of the Project on streamflows will be small and indistinguishable from natural variability. Water volumes from the stormwater ponds will be monitored to determine how much water, if any, is pumped into the natural environment.


12 References

Alberta Environment, 1999. Evaporation and evapotranspiration in Alberta, Report 1912 to 1985, Data 1912-1996. Water Sciences Branch, Water Management Division, Alberta Environmental Protection. Edmonton, Alberta.

Hatfield Consultants, 2012. VCI Advanced TriStar Project: Surface Aquatic Resources Baseline and Affects Assessment.

Linsley, R. K., Kohler, M.A., Paulhus, J.L.H., 1982, Hydrology for Engineers. 3rd edition. McGraw-Hill Inc., New York, New York

MEMS, 2012. Hydrogeology Assessment for VCI Advanced TriStar Project. Millennium EMS Solutions Ltd.

Morton. F.I, 1983. Operational estimates of aerial evapotranspiration and their significance to the science and practice of hydrology.

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HYDROLOGY ASSESSMENTFOR ADVANCED TRISTAR PROJECT

PROJECT AND STATION LOCATIONS

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Figure 4

HYDROLOGY ASSESSMENT FORADVANCED TRISTAR PROJECT

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MONTHLY AIR TEMPERATURES

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Rating Curve

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PROJECT LAYOUT

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