coal valley robb trend - appendix 8 - end pit lake report · 2014. 11. 3. · suite 200 – 850...

Appendix 8 End Pit Lake Report

Suite 200 – 850 Harbourside Drive, North Vancouver, British Columbia, Canada V7P 0A3 • Tel: 1.604.926.3261 • Fax: 1.604.926.5389 • www.hatfieldgroup.com

An Evaluation of Water Quality in Existing End-Pit Lakes in the Coal Valley Mine Area

Final Report

September 2011

Prepared for:

Coal Valley Resources Inc.Edson, Alberta

#200 - 850 Harbourside Drive, North Vancouver, BC, Canada V7P 0A3 • Tel: 1.604.926.3261 • Toll Free: 1.866.926.3261 • Fax: 1.604.926.5389 • www.hatfieldgroup.com

AN EVALUATION OF WATER QUALITY IN EXISTING END-PIT LAKES IN THE

COAL VALLEY MINE AREA

FINAL REPORT

Prepared for:

COAL VALLEY RESOURCES INC. BAG 5000

EDSON, ALBERTA T7E 1W1

Prepared by:

HATFIELD CONSULTANTS SUITE 200 – 850 HARBOURSIDE DRIVE

NORTH VANCOUVER, BC V7P 0A3

SEPTEMBER 2011

1648.2

Coal Valley Mine: An Evaluation of Water Quality i Hatfield In Existing End-Pit Lakes – Final

TABLE OF CONTENTS

LIST OF TABLES .......................................................................................... ii LIST OF FIGURES ......................................................................................... ii LIST OF APPENDICES ................................................................................. ii

1.0 INTRODUCTION AND BACKGROUND .............................................. 1

1.1 BACKGROUND ....................................................................................................... 1 1.1.1 Creation of End-Pit Lakes in Coal Mining ........................................................... 1 1.1.2 Summary of Existing Information for CVM End-Pit Lakes .................................. 4 1.2 STUDY OBJECTIVES .............................................................................................. 4

2.0 STUDY DESIGN AND FIELD METHODOLOGIES ............................. 7

2.1 LAKES SAMPLED ................................................................................................... 7 2.2 BATHYMETRIC MAPPING ...................................................................................... 7 2.3 DEPTH PROFILES .................................................................................................. 7 2.4 ANALYTICAL WATER SAMPLING ....................................................................... 10

3.0 RESULTS ........................................................................................... 11

3.1 LAKE BATHYMETRY ............................................................................................ 11 3.2 WATER QUALITY .................................................................................................. 11 3.3 LAKE STRATIFICATION AND TURNOVER ......................................................... 11 3.3.1 Holomictic Lakes .............................................................................................. 11 3.3.2 Meromictic Lakes .............................................................................................. 21 3.4 WINTER PROFILE ANALYSIS .............................................................................. 21 3.5 IONIC COMPOSITION ........................................................................................... 21 3.6 ANALYTICAL LAKE WATER QUALITY ................................................................ 23 3.6.1 Differences in Water Quality Between Epilimnion and Hypolimnion ................. 23 3.6.2 Trends in Pit 24 (Stirling Lake) Water Quality ................................................... 24 3.6.3 Lake Trophic Status .......................................................................................... 24

4.0 DISCUSSION OF RESULTS ............................................................. 32

4.1 WATER QUALITY AND THE ECOLOGICAL VIABILITY OF END-PIT LAKES ................................................................................................................... 32

4.2 LAKE STRATIFICATION AND TURNOVER ......................................................... 32 4.2.1 Patterns of Lake Stratification and Turnover in Lakes in the CVM Area ..... 32 4.2.2 Importance of Salinity of Water Inflows to End-Pit Lakes ................................. 33 4.2.3 Importance of Lake Depth ................................................................................ 33 4.2.4 Relative Importance of the Salinity of Inflow Water and Lake Depth ................ 33 4.2.5 Do Stratification and Lake Turnover Matter? .................................................... 34 4.3 COMPARISON WITH END-PIT LAKE DEVELOPMENT GUIDELINES ............... 37

5.0 CONCLUSIONS ................................................................................. 39

6.0 REFERENCES ................................................................................... 40

7.0 CLOSURE .......................................................................................... 42

Coal Valley Mine: An Evaluation of Water Quality ii Hatfield In Existing End-Pit Lakes – Final

LIST OF TABLES

Table 1 Assessment of end-pit lakes in Hatfield (2008) study against lake development criteria from End-Pit Lake Working Group (2004) and against Fairfax Lake. .................................................................................... 6

Table 2 Summary information on the lakes sampled as part of this study. ............... 8

Table 3 Geographic coordinates of sampling locations and sampling requirements. ................................................................................................ 9

Table 4 Analytical and monthly in situ water quality variables measured in each lake. ..................................................................................................... 9

Table 5 Water chemistry of sampled lakes. ............................................................. 25

Table 6 Changes in concentrations of water quality variables in Pit 24 (Stirling) Lake. ............................................................................................. 31

Table 7 Assessment of end-pit lakes against lake development criteria and the natural Fairfax Lake. ............................................................................. 38

LIST OF FIGURES

Figure 1 Location of lakes sampled in current study. .................................................. 2

Figure 2 Temperature depth profiles of sampled lakes. ............................................ 13

Figure 3 Dissolved oxygen depth profiles of sampled lakes. .................................... 15

Figure 4 Conductivity depth profiles of sampled lakes. ............................................. 17

Figure 5 Total dissolved solids depth profiles of sampled lakes. .............................. 19

Figure 6 Ionic characteristics of sampled end-pit lakes, a natural lake, groundwater, and surface watercourses. .................................................... 22

Figure 7 Relationship between end-pit lake volume and dissolved oxygen concentrations. ........................................................................................... 35

LIST OF APPENDICES

Appendix A1 Chemical Design Factors for End-Pit Lakes (from End-Pit Lakes Working Group [2004])

Appendix A2 Bathymetric Maps

Coal Valley Mine: An Evaluation of Water Quality 1 Hatfield In Existing End-Pit Lakes – Final

1.0 INTRODUCTION AND BACKGROUND

This report presents the results of an evaluation of water quality conditions in existing end-pit lakes that have been created as part of reclamation programs undertaken by Coal Valley Resources Inc. (CVRI) at their operations in the Coal Valley Mine area (CVM), approximately 90 km south of Edson, in west-central Alberta, on the eastern slopes of the Canadian Rocky Mountains. This project was conducted by Hatfield Consultants Partnership (Hatfield) for CVRI as an ongoing effort to improve the design and functionality of end-pit lakes at CVM. This report contains the results of five monthly monitoring sessions conducted between July 2010 and February 2011 on nine existing end-pit lakes created in the CVM area and a Fairfax Lake, a natural lake in the vicinity of the CVM area and CVM end-pit lakes. In addition, this report integrates the results of historical water quality monitoring data collected from a number of these end-pit lakes in the 1980s and 1990s.

1.1 BACKGROUND

1.1.1 Creation of End-Pit Lakes in Coal Mining

The continual creation and maintenance of end-pit lakes is an integral component of the CVRI reclamation programs at CVM. With additional end-pit lakes planned for projects in the Mercoal West and Yellowhead Tower Mine (MW/YT) extension areas and the proposed Robb Trend extension area, ensuring their design allows for long-term ecological functionality is an important aspect in their creation.

On completion of mining, final cut end-pits are created where there is an insufficient amount of overburden material available to reclaim the natural profile of the landscape. The construction of end-pit lakes is completed by replacing and reshaping the overburden removed during mining and allowing the end-pits to fill with water from constructed surface inflows, surface runoff, and/or groundwater intrusion.

End-pit lakes in Canada are considered as potential alternatives to restoration of original landscapes in part because of their potential for fish and aquatic habitat. Commonly, end-pit lakes are developed from abandoned metal mines, but are also common in coal mining areas (Castro and Moore 2000, Anderson and Hawkes 1985). Their development is a strategy for reclaiming final end-pits in west-central Alberta.

End-pit lakes are generally characterized by high maximum depth to low surface area ratio. Their shape is a function of the original mining techniques. End-pit lakes created from dragline operations tend to produce long and narrow lakes that are asymmetrical about the long axis of the lake; one side is generally steep-sided, while the opposite side has a more gentle slope. End-pit lakes created from truck and shovel operations tend to be rounder, deeper, and have consistently steep walls at one end of the lake (Mackay 1999).

!

!

ALBERTA

CALGARY

EDMONTON

Lovett LakeSilkstone LakeSilkstone Lake

Pit 24 (Stirling)Lake

Pit 35 Lake

Pit 45 Lake

Fairfax Lake

Pit 25 South

Pit 25 East

Pit 44 Lake

520000

520000

525000

525000

5870

000

5870

000

5875

000

5875

000

5880

000

5880

000

K:\Data\Project\MEMS1648\_MXD\MEMS1648_A_Lakes_20110602.mxd

0 1 20.5km

Projection: UTM Zone 11 NAD83Imagery from BC Airphotos and Bing Maps

Figure 1 Location of lakes sampled in current study.

1:85,000Scale

Mercoal West Mine Yellowhead Tower Mine

Pembina R.

40

South Block

Mercoal Phase 2

Coal Valley ExtensionROBB

COALSPURMERCOALMcLeod R.

McLe

od R.

Pembina R.

Coal Valley Mine

Proposed Mine Permit Boundary

t

!

!

ALBERTA

CALGARY

EDMONTON

Pit 142 Lake

504000

504000

508000

508000

5880

000

5880

000

5885

000

5885

000

K:\Data\Project\MEMS1648\_MXD\MEMS1648_B_Lakes_142_20110602.mxd

0 0.8 1.60.4km

Projection: UTM Zone 11 NAD83Imagery from Geobase SPOT Panchromatic 2009.

Figure 1 (Cont'd.)

1:50,000Scale

Mercoal West Mine Yellowhead Tower Mine

Pembina R.

40

South Block

Mercoal Phase 2

Coal Valley ExtensionROBB

COALSPURMERCOALMcLeod R.

McLe

od R.

Pembina R.

Coal Valley Mine

Proposed Mine Permit Boundary

t


1.1.2 Summary of Existing Information for CVM End-Pit Lakes

There have been two sets of limnological and ecological studies conducted on CVM end-pit lakes:

1. In the 1990s, studies were conducted on Lovett, Silkstone, and Stirling (Pit 24) lakes by Luscar (1994), Agbeti (1998) and Mackay (1999); and

2. In 2006, studies were conducted on Lovett, Silkstone, and Stirling (Pit 24) lakes plus Pit 35 and Pit 45 lakes (Hatfield 2008). The Hatfield (2008) focused on overall limnological characterization of CVM end-pit lakes and comparing and contrasting the limnological characteristics of CVM end-pit lakes to limnological characteristics of Fairfax Lake, a natural lake located in the vicinity of the CVM area.

The Hatfield (2008) study summarized the hydrological, chemical, and biological characteristics of the five end-pit lakes that were studied in comparison with those characteristics of Fairfax Lake and with end-pit lake development guidelines contained in End-Pit Lakes Working Group (2004); these results are summarized in Table 1.

The Hatfield (2008) study concluded that, because of the considerable variation in water quality, sediment quality, and biological characteristics among the end-pit lakes and in comparison to Fairfax Lake, it was unclear which factors (i.e., time since establishment, presence of inflows and outflows, type of mixing, flushing rates, bathymetry, habitat complexity, or other characteristics), were more important to end-pit lake development, to what degree these factors influenced the ecological viability of end-pit lakes, and how these factors interacted to produce sustainable lake ecosystems.

1.2 STUDY OBJECTIVES

This study focused on the water quality component of the limnological and ecological characteristics of CVM end-pit lakes, specifically the Chemical Design Factors for end-pit lakes contained in End-Pit Lakes Working Group (2004). Design guidelines, indicators, and criteria for Chemical Design Factors contained in End-Pit Lakes Working Group (2004) are provided in Appendix A1.

Because end-pit lakes are part of ongoing reclamation activities being implemented by CVRI in the CVM area and will form part of reclamation and closure plans for new and proposed mining projects, CVRI decided to update the water quality information from nine existing end-pit lakes in the CVM area. This would increase the understanding of ecological sustainability of end-pit lakes created from surface coal mine pits using conventional techniques and provide guidance to the design and management of future end-pit lakes.


Key questions guiding this study were:

1. Are end-pit lakes in the CVM area experiencing turnover and what is their mixing regime?

2. What is the water chemistry, at both the surface (epilimnion) and near bottom (hypolimnion) within these lakes?

3. What influences maybe impacting the mixing regime within the nine end-pit lakes?

4. How do environmental conditions in end-pit lakes change over time?

5. What are the similarities and differences in water quality indicators between end-pit lakes and natural lakes found in the same ecoregion and how have these changed over time?

6. What lessons for future end-pit lake development can be learned from the observed water quality conditions in existing end-pit lakes?


Table 1 Assessment of end-pit lakes in Hatfield (2008) study against lake development criteria from End-Pit Lake Working Group (2004) and against Fairfax Lake.

Design Factors1 Indicators1 Variable1 Fairfax Lake Pit 35 Lake Silkstone Lake Pit 45 Lake Stirling Lake

(Pit 24) Lovett Lake

Hydrological

Inlet Presence/ absence Absence Absence Presence Presence Absence Absence

Outlet Presence/ absence Presence Presence Presence Presence Absence Presence*

Sediment Yield-Erosion

Total suspended solids 3 mg/L

Within range

(3-5 mg/L)

Within range

(3-5 mg/L)

Within range

(3-5 mg/L)

Within range

(3-5 mg/L)

Within range

(3-5 mg/L)

Chemical

Toxic Substances

Water guidelineexceedances

sulphide, cadmium

exceedances

similar sulphide,exceeded

phosphorus

similar sulphide, cadmium, exceeded selenium

similar sulphide, cadmium, exceeded aluminum

similar sulphide, exceeded TKN, TP at low depth

similar sulphide, exceeded TP,

TKN at low depth

Overturn Summer

stratification Presence Presence Presence Presence Presence Presence

Fall mixing Presence Absence Absence Absence Absence Absence

Biological

Biodiversity

Diversity of phytoplankton 12 taxa lower (10) higher (15) lower (9) lower (6) lower (10)

Diversity of zooplankton 22 taxa lower (11) lower (13) lower (13) lower (18) lower (13)

Biomass/ Productivity

Biovolume of phytoplankton 214 µm3/m3 lower (79) lower (92) higher (574) lower (12) lower (114)

Biomass of zooplankton 674 mg/m3 lower (345) lower (343) lower (186) lower (130) lower (180)

Biomass of benthic

invertebrates

6,450 individuals/m2

lower (4,233) higher (40,167) higher (14,183) lower (2,033) higher (15,917)

Fish Habitat Effectiveness

Diversity of invertebrates 11 taxa lower (2) equal (11) lower (6) lower (3) within range (10)

1 From End-Pit Lake Working Group (2004). Note End-pit lake assessments were reported based on comparisons with Fairfax Lake characteristics. * Subsurface outflow is present (spring that feeds the Lovett River).


2.0 STUDY DESIGN AND FIELD METHODOLOGIES

2.1 LAKES SAMPLED

Nine end-pit lakes and one natural lake were sampled on six occasions between July 2010 and June 2011; basic information on the sampled lakes is provided in Table 2.

Table 3 contains the coordinates of the sampling locations within each of the ten sampled lakes. Sampling locations correspond to the deepest portion of the lake, determined through bathymetric mapping. Water quality variables that were measured are presented in Table 4.

2.2 BATHYMETRIC MAPPING

Bathymetric mapping was conducted from July 26 to July 28, 2010 on four end-pit lakes for which bathymetric maps did not already exist (Pit 25 East, Pit 25 South, Pit 44 and Pit 142 lakes), and from June 6 to June 8 2011 on two end-pit lakes for which only paper copies of bathymetric maps existed (Lovett and Silkstone lakes).

Soundings were made using a digital sonar system consisting of a Lowrance HDS sonar with a split beam 83/200 KHz transducer, a computer to control the sounder and record data, and an internal Lowrance 16-channel GPS+WAAS differential GPS to geo-code data as they were collected. Sonar recordings at each lake were made on a grid of transects spaced approximately 10 to 20 m apart depending on depth (shallow areas require finer transect resolution). Additional transects were made of the shoreline area and shallow bays to improve accuracy. The geographic location of the shoreline of each end-pit lake was surveyed by CVRI; results were provided to Hatfield as .csv files with locations coded in UTMs.

Digital data files obtained during the fieldwork were processed with DrDepth software to create echograms and .dxf and shape files containing contours of depth, latitude, and longitude for each sounding. ArcGIS 9.3 software was then used to post-process each map, convert the files to NAD 83 and interpolate the depth scale into a regular colour pattern scale.

2.3 DEPTH PROFILES

Depth profiles of a number of water quality variables were completed in all ten lakes during each sampling event. Monthly profiles were used to monitor lake mixing regime and determine the location (lake depth) of any thermoclines, chemoclines and oxyclines within the water column. Monthly water quality profiles were conducted using an HI 9828 Hanna multi-meter probe with an associated 20 m data cable. Water quality variables that were measured in the depth profiles are listed in Table 4.


Table 2 Summary information on the lakes sampled as part of this study.

Lake Year

Created (Age)

Type Location Approximate Surface Area

(ha)

MaximumDepth (m)

Mean Depth

(m) Inflow Outflow Water

Sampling Monitoring

History

End-Pit Lakes

Lovett Lake 1985 (26) Dragline 10-47-19-W5M 6.0 18 5.5 √* Ions 1987, 1989, 1991,

1993, 1998, 2006

Silkstone Lake 1986 (25) Dragline 9-47-19-W5M 6.4 14.8 4.7 √ √ Full, Ions 1987, 1989, 1991,

1993, 1998, 2006

Pit 24 (Stirling)

1993 (18) Truck and shovel 4-47-19-W5M 4.9 23.5 8.1 Full, Ions 1998, 2006

Pit 35 1999 (12) Dragline 26-46-19-W5M 3.5 11.4 5.7 √ Ions 2006

Pit 45 1999 (12) Dragline 26-46-19-W5M 6.5 12.5 6.3 √ √ Ions 2006

Pit 44 1998 (13) Dragline 35-46-19-W5M 8.76 18.5 7.4 √ √ Full, Ions Not monitored prior to 2010

Pit 142 2005 (6) Dragline 24-47-21-W5M 7.24 7.4 2.2 √ √ Ions Not monitored prior to 2010

Pit 25E 1996 (15) Dragline 27-46-19-W5M 6.8 16.2 7.4 √ √ Full, Ions Not monitored prior to 2010

Pit 25S 1999 (12) Dragline 33-46-19-W5M 6.8 12.5 4.7 √ √ Ions Not monitored prior to 2010

Natural Lakes

Fairfax Lake Natural Natural 17-46-18-W5M 28.4 7.6 3.2 √ Full, Ions 1998, 2006

Full = full suite of water quality variables listed in Table 4. Ions = only major ions listed in Table 4. * Outflow is through a subsurface connection to Lovett River.


Table 3 Geographic coordinates of sampling locations and sampling requirements.

Lake Sampling Conducted

Sampling Location

(NAD83, Zone 11)

July 2010

August 2010

September 2010

October 2010

February 2011

June 2011 Easting Northing

End-Pit Lakes

Lovett 1 1 1 1 1 1,2 519831 5876770

Silkstone 1,3 1 1 1,3 ns 1,2 519005 5877082

Pit 24 1,3 1 1 1,3 1 1 519041 5875821

Pit 35 1 1 1 1 1 1 523473 5871553

Pit 45 1 1 1 1 1 1 523704 5871913

Pit 44 1,2,3 1 1 1,3 ns 1 523263 5872762

Pit 142 1,2 1 1 1, 1 1 504351 5880574

Pit 25E 1,2,3 1 1 1,3 1 1 522491 5871813

Pit 25S 1,2 1 1 1 1 1 520671 5873200

Natural Lakes

Fairfax 1,3 1 1,3 1 1 528202 5869205

1 – Monthly water column profiles. 2 – Bathymetric mapping. 3 – Analytical water quality sampling. ns – not sampled due to unsafe ice conditions.

Table 4 Analytical and monthly in situ water quality variables measured in each lake.

In situ Water Quality Depth Profile Variables

dissolved oxygen, conductivity, total dissolved solids, temperature

Conventional Variables dissolved organic carbon, pH, total alkalinity, total dissolved solids, total hardness, total suspended solids, total organic carbon, turbidity

Major Ions bicarbonate, calcium, carbonate, chloride, magnesium, potassium, sodium, sulphate, sulphide

Nutrients ammonia-N, nitrate-N, nitrite-N, total Kjeldahl nitrogen, total phosphorus

Organics/Hydrocarbons naphthenic acids, total phenols, total recoverable hydrocarbons

Metals (total and dissolved) aluminum, antimony, arsenic, barium, beryllium, boron, cadmium, chromium, cobalt, copper, iron, lead, manganese, mercury, ultra-trace mercury1, molybdenum, nickel, selenium, silver, strontium, sulphur, thallium, uranium, vanadium, zinc

1 Total only, sampled with a detection limit of 0.6 ng/L.


Data were subsequently recorded on field note books and downloaded onto field laptops at the end of each day.

2.4 ANALYTICAL WATER SAMPLING

Analytical water samples were collected from a representative subset of four end-pit lakes (Pit 24, Pit 25E, Pit 44 and Silkstone) as well as Fairfax Lake (natural reference lake).

Analytical sampling for selected lakes consisted of one sample collected in July, within the epilimnion (two m below surface), a second set of two samples collected in October (one from the epilimnion and one from the hypolimnion, approximately three m above the lake bottom) and, where possible, a third set of samples collected from the epilimnion and hypolimnion in February 2011. Due to unsafe ice conditions Pit 44, and Silkstone Lake were not sampled in February 2011. Analytical samples were collected at the same location as water quality depth profiles.

During sampling all field personnel followed Hatfield’s ISO9001-certified water quality standard operating procedures. Analytical samples were collected using 3.2 L vertical Van Dorn hand deployed from the side of a boat. The sampler was armed and deployed to the required depth using depth markers on the deployment line. Once triggered the sampler was retrieved to the surface, the pour spout opened and each sample container filled according to laboratory specifications. Where required, samples were filtered using 0.45 µm pore size membrane filters mounted to 60 ml disposable Luerlok Swinnex syringes.

A field blank, trip blank and field split were also collected for QA/QC purposes.

Water quality samples were analyzed by ASL Labs in Edmonton, Alberta; water quality variables that were measured are provided in Table 4.


3.0 RESULTS

Figure 6 presents the ionic characteristics of sampled end-pit lakes, groundwater, and surface water in the study area for 2006 and 2010.

3.1 LAKE BATHYMETRY

The bathymetric maps of all nine end-pit lakes and Fairfax Lake are provided in Appendix A2.

The bathymetric characteristics of the four newly mapped end-pit lakes (Pit 25E, Pit 25S, Pit 44 and Pit 142 lakes; Appendix A2) reflect their origin. All four lakes were created from pits made by dragline operations, resulting in long narrow basins with cross-sections that are steep-sided, steeper on one side than the other, and moderately deep. Contouring techniques used during the reclamation process have reduced the steep-sidedness of Pits 142, 25E and 25S creating a more uniform depth profile. Final reclamation has not yet been completed on Pit 44 and this is reflected in the steep-sided “high-wall” along the western shoreline and its relatively irregular shape (Figure A2.9, Appendix A2).

3.2 WATER QUALITY1

3.3 LAKE STRATIFICATION AND TURNOVER

Figure 2 to Figure 5 present the depth profiles of in situ water quality variables measured monthly in each of the ten lakes between July 2010 and October 2010, February 2011 and June 2011. During the February 2011 field program insufficient ice thickness prevented water quality data collection from Silkstone and Pit 44 lakes.

3.3.1 Holomictic Lakes

Three end-pit lakes, Pit 35, Pit 142, Pit 25S lakes, as well as Fairfax Lake were holomictic2 in 2010. Fall lake turnover had occurred in these four lakes by the time October 2010 sampling was conducted (Figure 2 to Figure 5). These four lakes showed stratification in temperature and dissolved oxygen during the summer months (Figure 2 to Figure 5) but there was little variation in these water quality variables with depth observed post-turnover. Based on the water quality results and sampling periods, it is estimated that Pit 142, Pit 35 and Fairfax lakes experienced complete turnover sometime between mid-August and early September while Pit 25S Lake experienced complete turnover sometime between mid-September and early October. Stratification had re-established in these lakes in June 2011 after the 2010/2011 winter season.

1 Unless indicated, concentrations of all metals presented in this report are for total metals. 2 A holomictic lake is a lake with water that, at some time during the year, has a uniform temperature and density from top

to bottom, allowing lake waters to completely mix.


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Figure 2 Temperature depth profiles of sampled lakes.

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Pit 45

Lovett

Pit 25E

Pit 25S

Pit 142

Silkstone

Pit 44

Pit 24

Pit 35

Note: Pit 44 and Silkstone Lakes were not sampled in February 2011 due to unsafe ice conditions.


Figure 3 Dissolved oxygen depth profiles of sampled lakes.

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July 2010

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Figure 4 Conductivity depth profiles of sampled lakes.

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September 2010

Fairfax

Pit 45

Lovett

Pit 25E

Pit 25S

Pit 142

Silkstone

Pit 44

Pit 24

Pit 35

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Fairfax

Pit 45

Lovett

Pit 25E

Pit 25S

Pit 142

Silkstone

Pit 44

Pit 24

Pit 35

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Pit 25E

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Pit 142

Pit 24

Pit 35

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Pit 45

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Pit 25E

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Pit 35



Figure 5 Total dissolved solids depth profiles of sampled lakes.

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Fairfax

Pit 45

Lovett

Pit 25E

Pit 25S

Pit 142

Silkstone

Pit 44

Pit 24

Pit 35

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Fairfax

Pit 45

Lovett

Pit 25E

Pit 25S

Pit 142

Silkstone

Pit 44

Pit 24

Pit 35

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Lovett

Pit 25E

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Pit 142

Silkstone

Pit 44

Pit 24

Pit 35

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Pit 142

Silkstone

Pit 44

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Pit 35

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Pit 45

Lovett

Pit 25E

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Pit 44

Pit 24

Pit 35



3.3.2 Meromictic Lakes

Lovett, Pit 25E, Pit 24, Silkstone, Pit 45, and Pit 44 lakes showed distinct stratification throughout the sampling program (Figure 2 to Figure 5) although the location of the thermocline and oxycline migrated towards the bottom of these lakes in late summer and early fall, suggesting partial water column mixing of the epilimnion may have occurred. Dissolved oxygen levels in these lakes remained high in the epilimnion (i.e., greater than 8.0 mg/L) but decreased significantly below the oxycline to near zero mg/L (Figure 3). The stratification observed in these end-pit lakes in October 2010 (Figure 2 to Figure 5) suggests either lake turnover had not yet occurred or that these lakes are meromictic and do not turn over.

3.4 WINTER PROFILE ANALYSIS

Water quality profiles collected during the winter field program (February 2011) are discussed separately as ice-on periods provide very different limnological conditions that influence the mixing regime in most lakes (Patterson and Hamblin 1988; Reynolds 1997; Lewis 1983). In general, surface ice limits the influence of mixing capabilities associated with wind and overland inflow and outflow of water. In addition, water density differences begin to form as surface water temperatures fall below 4oC and lakes begin to form inverse thermal stratification. In February 2011, all of the studied lakes had formed shallow, yet distinct, thermoclines in the top two m, with temperatures increasing from 00C at near surface depths to approximately 3.50C at two m (Figure 2). Temperatures became generally stable below two m ranging from 3.50C to 5.50C at lake bottoms. Concentrations of dissolved oxygen declined consistently with increasing depth in all lakes from three to six mg/L at the surface to near zero mg/L at greater depth (Figure 3). Conductivity and concentration of total dissolved solids (TDS) changed little between fall and winter indicating lakes described as meromictic (Section 3.3.2) remained as such and did not experience fall turnover in 2010.

3.5 IONIC COMPOSITION

The ionic composition of most of the end-pit lakes that were sampled in this study and in the Hatfield (2008) study was dominated by sodium and bicarbonate, with lesser amounts of calcium and sulphate (Figure 6). The ionic composition of most of the end-pit lakes is intermediate to that of: (i) surface waters whose anions are also dominated by bicarbonate and whose cations are also dominated by sodium but contain from 20% to 40% calcium; and (ii) groundwater, whose cations contain sodium but no calcium, and whose anions are almost exclusively bicarbonate. The exceptions to this pattern are:

Pit 35 Lake which has an ionic composition similar to surface waters in the CVM area (Figure 6);

The epilimnion of Pit 44 Lake and anions still dominated by bicarbonate with sulphate but also containing higher concentrations of calcium than other end-pit lakes; and

Pit 25E Lake which has higher concentrations of calcium and sulphate than other end-pit lakes.


Figure 6 Ionic characteristics of sampled end-pit lakes, a natural lake, groundwater, and surface watercourses.


3.6 ANALYTICAL LAKE WATER QUALITY

Analytical water quality samples were collected from:

Pit 24, Pit 25E, Pit 44, Silkstone, and Fairfax lakes in July 2010 in which single grab samples were collected from mid-depth according to depth sounder measurements;

Pit 24, Pit 25E, Pit 44, Silkstone, and Fairfax lakes in October 2010 in which two samples were collected in each end-pit lake, one from the epilimnion and one from the hypolimnion, and a single sample collected from Fairfax Lake at mid-depth; and

Pit 24, Pit 25E, and Fairfax lakes in February 2011 in which a hypolimnion and epilimnion sample were collected from Pit 24 Lake and single mid-depth samples were collected from Pit 25E and Fairfax lakes.

In general, all end-pit lakes in all seasons had higher levels of alkalinity, bicarbonate, major ions, conductivity, TDS, and hardness than Fairfax Lake (Table 5). All end-pit lakes had lower levels of dissolved organic carbon (DOC) than Fairfax Lake and none of the lakes, including Fairfax Lake, were circumneutral in 2010. All lakes had low TSS ranging from <3 to seven mg/L. Concentrations of TDS, a measure of total ion content, were three to ten times greater in the end-pit lakes relative to Fairfax Lake, and the highest TDS were recorded in Pit 25E Lake (1,110 mg/L, 1,130 mg/L and 1,140 mg/L in July 2010, October 2010, and February 2011, respectively). The concentrations of all major ions were higher in the end-pit lakes than in Fairfax Lake.

There were few exceedances of water quality guidelines for the protection of aquatic life measured in the end-pit lakes in 2010 (Table 5). Most of the cases in which concentrations of water quality variables exceeded their guideline are attributable to phenols and total phosphorus. In addition, single sample exceedances in concentration of dissolved and total chlorine and total arsenic were recorded in Silkstone Lake and in concentration of total iron in Fairfax Lake. These guideline exceedances were generally similar to those found in Hatfield (2008) and in the historical lake monitoring of Lovett and Stirling Lake (Agbeti 1998).

3.6.1 Differences in Water Quality Between Epilimnion and Hypolimnion

There were differences in water quality between the hypolimnion and epilimnion in the meromictic lakes sampled for full water quality in October 2010 and for Pit 24 Lake in February 2011. With the exception of pH, concentrations of all measured water quality variables were higher in the hypolimnion than the epilimnion for all sampled meromictic end-pit lakes (Table 5), and both water quality guideline exceedances measured in October 2010 and February 2011 were in the hypolimnion of the sampled lakes.


3.6.2 Trends in Pit 24 (Stirling Lake) Water Quality

Pit 24 Lake water chemistry has been monitored in 1998 (five years after reclamation, Agbeti [1998]), 2006 (13 years after reclamation, Hatfield [2008]) and in the summer, fall and winter of 2010 (17 years after reclamation, current study). In general, nutrients, physical variables and concentrations of major ions have decreased overtime in both the epilimnion and hypolimnion (Table 6). TDS concentrations have also decreased since lake formation suggesting a decrease in salinity.

3.6.3 Lake Trophic Status

In 2010, all sampled lakes at all sampled depths had nutrient concentrations corresponding to an oligotrophic trophic status as defined in Wetzel (2001)3 and confirm results from earlier studies (Agbeti 1998, Hatfield 2008). These results indicate that low productivity in end-pit lakes, as well as in Fairfax Lake, have been consistent over time. Lakes on the eastern slopes of the Rocky Mountains are generally oligotrophic4. These results also suggest that meromixis in end-pit lakes does not necessarily inhibit overall trophic status relative to natural lakes in the region.

3 Oligotrophic: total phosphorus: 0.008 mg/L, total nitrogen: 0.661 mg/L. Mesotrophic: total phosphorus: 0.0267 mg/L, total nitrogen: 0.753 mg/L. Eutrophic: total phosphorus: 0.0844 mg/L, total nitrogen: 1.875 mg/L. 4 http://environment.alberta.ca/01715.html.


Table 5 Water chemistry of sampled lakes.

Water Quality Variable Units Regulatory Guideline

Detection Limit

Pit 24 Pit 25E Pit 44 Silkstone Fairfax Pit 24 (Hypo)

Pit 24 (Epi)

Pit 25E (Hypo)

Pit 25E (Epi)

Pit 44 (Hypo)

Pit 44 (Epi)

Silkstone (Hypo)

Silkstone (Epi) Fairfax Pit 24

(Epi) Pit 24 (Hypo) Pit 25E Fairfax

July 2010 October 2010 February 2011

Physical Variables, Nutrients, Ions and Organics/Hydrocarbons Alkalinity, Total (as CaCO3) mg/L 5 241 430 304 539 71.9 253 187 431 226 301 210 521 275 70.7 208 312 463 81.6 Ammonia-N mg/L 1.37A 0.05 <0.05 0.15 0.132 0.474 <0.05 <0.05 <0.05 0.101 <0.05 0.159 <0.05 0.248 <0.05 <0.05 <0.05 0.851 0.136 0.091 Bicarbonate (HCO3) mg/L 5 272 524 371 657 87.7 292 214 500 256 356 239 599 305 86.3 251 380 565 99.5 Biochemical Oxygen Demand mg/L 2 <2 <2 <2 <2 <2 - - - - - - - - <2 2.7 7.9 <2 2.2 Calcium, Dissolved mg/L 0.5 28.3 109 75.2 58.8 18.9 29.3 19.4 106 53.3 77.1 30.5 56.2 32.3 16.9 22.2 33.2 107 18.7 Carbonate (CO3) mg/L 5 11 <5 <5 <5 <5 8.6 7 12.7 9.7 5.2 8.4 18.4 14.6 <5 <5 <5 <5 <5 Chloride (Cl) mg/L 0.5 <0.5 <0.5 <0.5 0.99 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 1.87 0.62 <0.5 <0.5 <0.5 <0.5 <0.5 Color, True T.C.U. 2 19 7 4 9 12 3 3 5.0 13 <2 <2 8 9 10 5 8 8 19 Conductivity (EC) µS/cm 0.2 560 1590 804 1150 144 573 446 1550 692 803 555 1090 579 143 467 637 1590 151 Dissolved Organic Carbon mg/L 1 3.8 2.8 1.9 3.7 7.5 2.9 4.9 1.6 1.8 3.6 4.8 7.9 3.7 3.5 3.6 8.2 Hardness (as CaCO3) mg/L 118 417 240 216 61.1 120 86 403 205 246 108 207 127 55.8 95.9 131 406 60.9 Hydrocarbons, Recoverable (I.R.) mg/L 1 <1 <1 <1 <1 <1 - - - - - - - - <1 <1 <1 <1 <1 Hydroxide (OH) mg/L 5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 Magnesium (Mg)-Dissolved mg/L 0.1 11.4 35.1 12.6 16.9 3.38 11.4 9.13 33.5 17.4 12.9 7.66 16.3 11.3 3.3 9.82 11.8 33.8 3.45 Naphthenic Acids mg/L 1 <1 <1 <1 <1 <1 - - - - - - - - <1.0 <1.0 <1.0 <1.0 <1.0 Nitrate (as N) mg/L 13B 0.05 <0.05 0.132 <0.05 <0.05 <0.05 <0.05 <0.05 0.124 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 0.066 <0.050 Nitrate and Nitrite as N mg/L 0.071 <0.071 0.132 <0.071 <0.071 <0.071 <0.071 <0.071 0.124 <0.071 <0.071 <0.071 <0.071 <0.071 <0.071 <0.071 <0.071 <0.071 <0.071 Nitrite (as N) mg/L 0.06B 0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.050 pH pH 6.5-9C 0.1 8.45 7.87 7.88 7.92 7.74 8.52 8.55 8.41 8.53 8.35 8.54 8.47 8.61 8.15 8.32 8.09 8.00 8.01 Phenols (4AAP) mg/L 0.004 0.001 0.0041 <0.001 0.0046 0.0087 0.0023 - - - - - - - - 0.0037 0.0016 0.0035 <0.0010 0.0026 Phosphorus, Total mg/L 0.05D 0.001 0.0147 0.0206 0.0035 0.164 0.0157 0.0129 0.0073 0.0144 0.0057 0.003 0.011 0.0688 0.0094 0.0145 0.0109 0.279 0.0053 0.0091 Phosphorus, Total Dissolved mg/L 0.001 0.004 0.0024 <0.001 0.0964 0.0094 0.0059 0.0013 0.0033 <0.001 <0.001 0.0125 0.0426 0.0017 0.0033 0.0079 0.237 0.0023 0.009 Potassium, Dissolved mg/L 0.5 2.94 5.6 3.61 3.16 0.76 2.67 2.4 4.99 2.11 3.56 2.98 2.99 2.07 0.77 2.91 3.2 5.42 0.92 Sodium, Dissolved mg/L 1 77.9 227 88.6 189 6.4 76.8 60.5 204 70.1 85.9 75.4 179 77.7 6.3 69.6 91.9 214 6.6 Sulfate (SO4) mg/L 0.5 57 434 125 101 1.19 55.7 47.2 421 137 130 78.2 96.6 43 1.11 53.8 47.6 445 1.07 Sulphide mg/L 0.002 <0.002 <0.002 <0.002 0.121 <0.002 <0.002 <0.002 <0.002 <0.002 <0.002 <0.002 <0.002 <0.002 <0.002 <0.002 0.207 <0.002 <0.002 Total Dissolved Solids mg/L 5 336 1110 512 747 99 347 266 1130 451 541 336 734 353 85 281 397 1140 100 Total Kjeldahl Nitrogen mg/L 0.2 0.34 0.34 0.22 0.91 0.81 0.23 0.23 0.31 0.22 0.25 <0.2 0.56 0.3 0.41 0.34 1.28 0.33 0.47 Total Organic Carbon mg/L 1 3.6 2.9 1.9 4.3 7.8 3 4.9 1.6 2 3.7 4.9 8.7 4.2 4.4 3.8 8.2 Total Suspended Solids mg/L 3 5 <3 <3 <3 7 <3 <3 <3 <3 <3 <3 5 <3 <3 <3 3 <3 <3

Bold Below detection limit. XXX Guideline exceedance. * Metals were not analyzed in October. 1 Guidelines are Alberta Environment (1999) unless otherwise specified. A at pH 8.0, 10°C (CCME 2007). B CCME guideline for nitrate is 13 mg/L; CCME guideline for nitrite is 0.060 mg/L. C CCME (2007). AENV (1999) guideline: "To be in the range of 6.5 to 8.5 but not altered by more than 0.5 pH units from background”. D Guideline is for chronic total (inorganic and organic) phosphorus. E at pH>=6.5; [Ca2+]>=4 mg/L; DOC>=2 mg/L (CCME 2007). F Is equal to 10(0.86*LOG(Hardness)-3.2) (CCME 2007). G Guideline for chromium III is 0.0089 mg/L; guideline for chromium VI is 0.0010 mg/L (CCME 2007). Most stringent guideline (0.0010 mg/L) is used. H Guideline is hardness-dependent: 0.002 mg/L at hardness = 0 to 120 mg/L; 0.003 mg/L at hardness = 120 to 180 mg/L; 0.004 mg/L at hardness > 180 mg/L (CCME 2007). I Guideline is hardness-dependent: 0.001 mg/L at hardness = 0 to 60 mg/L; 0.002 mg/L at hardness = 60 to 120 mg/L; 0.004 mg/L at hardness > 120 mg/L (CCME 2007). J Chronic guideline (AENV 1999). K Guideline is hardness-dependent: 0.025 mg/L at hardness = 0 to 60 mg/L; 0.065 mg/L at hardness = 60 to 120 mg/L; 0.11 mg/L at hardness = 120 to 180 mg/L; 0.15 mg/L at hardness > 180 mg/L (CCME 2007).


Table 5 (Cont’d.)

Water Quality Variable Units Regulatory

Guideline Detection

Limit Pit 24 Pit 25E Pit 44 Silkstone Fairfax Pit 24

(Hypo) Pit 24 (Epi)

Pit 25E (Hypo)

Pit 25E (Epi)

Pit 44 (Hypo)

Pit 44 (Epi)

Silkstone (Hypo)




Dissolved Metals Aluminum mg/L 0.1E 0.001 0.000718 0.000813 0.00027 0.000898 0.000247 * * * * * * * * * 0.00352 0.00217 0.000556 0.000415 Antimony mg/L 0.000001 0.0000855 0.000166 0.00014 0.0000918 0.0000279 * * * * * * * * * 0.0000844 0.0000926 0.00014 0.0000252 Arsenic mg/L 0.005 0.00004 0.00101 0.000304 0.000393 0.00498 0.000413 * * * * * * * * * 0.00082 0.00124 0.000295 0.000349 Barium mg/L 0.0001 0.0914 0.0796 0.0813 0.195 0.0479 * * * * * * * * * 0.0729 0.126 0.0745 0.0411 Beryllium mg/L 0.00001 <0.000003 <0.000003 <0.000003 <0.000003 <0.000003 * * * * * * * * * 0.0000035 <0.000003 0.0000118 0.0000065 Bismuth mg/L 0.00001 <0.000001 <0.000001 <0.000001 <0.000001 0.0000111 * * * * * * * * * <0.000001 <0.000001 <0.000001 <0.000001 Boron mg/L 0.0008 0.0241 0.0463 0.0514 0.0584 0.00529 * * * * * * * * * 0.0224 0.0298 0.0498 0.00682 Cadmium mg/L F 0.000006 0.0000021 0.0000303 0.000025 0.0000035 0.0000028 * * * * * * * * * 0.0000026 <0.000002 0.0000319 <0.000002 Calcium mg/L 0.1 23.9 107 70.3 48.6 18.8 * * * * * * * * * 21.3 30.1 104 18.5 Chlorine mg/L 0.5 0.3 <0.1 0.25 0.186 0.704 0.148 * * * * * * * * * <0.1 0.153 0.303 0.206 Chromium mg/L 0.001G 0.0003 0.0000742 0.0000307 0.000112 0.000132 <0.00003 * * * * * * * * * 0.0000653 0.0000487 <0.00003 <0.00003 Cobalt mg/L 0.00001 0.0000206 0.000126 0.0000977 0.000732 0.0000184 * * * * * * * * * 0.0000157 0.000145 0.00076 0.0000101 Copper mg/L 0.002H 0.0001 0.000233 0.000633 0.000376 0.000256 0.0000903 * * * * * * * * * 0.000392 0.000223 0.000695 0.000115 Iron mg/L 0.3 0.004 <0.002 <0.002 <0.002 0.0179 0.0592 * * * * * * * * * <0.002 0.0219 <0.002 0.0419 Lead mg/L 0.001I 0.00001 <0.000001 <0.000001 <0.000001 0.000003 <0.000001 * * * * * * * * * 0.0000019 0.0000077 0.0000101 0.0000028 Lithium mg/L 0.0002 0.00539 0.0298 0.0297 0.0188 0.00198 * * * * * * * * * 0.00551 0.00824 0.0425 0.00405 Manganese mg/L 0.00003 0.000341 0.161 0.178 1.68 0.373 * * * * * * * * * 0.000233 1.23 0.638 0.00106 Mercury mg/L 0.013J, 0.005 0.00005 <0.00001 <0.00001 <0.00001 <0.00001 <0.00001 * * * * * * * * * <0.00001 0.0000206 <0.00001 <0.00001 Molybdenum mg/L 0.073 0.000008 0.00165 0.00275 0.0107 0.00188 0.000413 * * * * * * * * * 0.00192 0.000502 0.00272 0.000355 Nickel mg/L 0.025K 0.00006 0.000319 0.00246 0.00339 0.00149 <0.000005 * * * * * * * * * 0.000289 0.000223 0.00407 <0.000005 Selenium mg/L 0.001 0.0003 0.000252 0.000661 0.000635 0.000233 <0.0001 * * * * * * * * * 0.000237 0.000129 0.000583 <0.0001 Silver mg/L 0.0001 0.000005 <0.0000005 0.0000065 0.0000008 0.0000026 <0.0000005 * * * * * * * * * 0.0000006 <0.0000005 <0.0000005 <0.0000005Strontium mg/L 0.000008 0.501 1.96 1.43 1.43 0.12 * * * * * * * * * 0.415 0.582 1.93 0.123 Sulphur mg/L 0.6 19.6 190 53.6 41.7 0.476 * * * * * * * * * 17.4 17.2 150 0.354 Thallium mg/L 0.0008 0.000003 0.0000022 0.0000104 0.000004 <0.0000003 0.0000121 * * * * * * * * * 0.0000026 0.0000007 0.0000151 <0.0000003Thorium mg/L 0.00003 0.0000025 0.0000037 0.0000021 0.0000026 0.0000218 * * * * * * * * * 0.0000022 0.0000027 0.0000027 <0.0000003Tin mg/L 0.00007 <0.00003 <0.00003 <0.00003 <0.00003 <0.00003 * * * * * * * * * <0.00003 <0.00003 <0.00003 <0.00003 Titanium mg/L 0.00007 0.000292 0.000673 0.000353 0.00173 0.000313 * * * * * * * * * 0.000119 0.00125 0.00054 0.000236 Uranium mg/L 0.000003 0.0012 0.00518 0.00191 0.00107 0.0000327 * * * * * * * * * 0.00116 0.00106 0.00557 0.00004 Vanadium mg/L 0.00005 0.000205 0.000133 0.0000543 0.000628 0.0000282 * * * * * * * * * 0.000211 0.000361 0.0000671 0.000007 Zinc mg/L 0.03 0.0002 0.00021 0.00189 0.00353 0.00127 0.00144 * * * * * * * * * 0.00227 0.000804 0.00212 0.000644

Bold Below detection limit. XXX Guideline exceedance. * Metals were not analyzed in October. 1 Guidelines are Alberta Environment (1999) unless otherwise specified. A at pH 8.0, 10°C (CCME 2007). B CCME guideline for nitrate is 13 mg/L; CCME guideline for nitrite is 0.060 mg/L. C CCME (2007). AENV (1999) guideline: "To be in the range of 6.5 to 8.5 but not altered by more than 0.5 pH units from background”. D Guideline is for chronic total (inorganic and organic) phosphorus. E at pH>=6.5; [Ca2+]>=4 mg/L; DOC>=2 mg/L (CCME 2007). F Is equal to 10(0.86*LOG(Hardness)-3.2) (CCME 2007). G Guideline for chromium III is 0.0089 mg/L; guideline for chromium VI is 0.0010 mg/L (CCME 2007). Most stringent guideline (0.0010 mg/L) is used. H Guideline is hardness-dependent: 0.002 mg/L at hardness = 0 to 120 mg/L; 0.003 mg/L at hardness = 120 to 180 mg/L; 0.004 mg/L at hardness > 180 mg/L (CCME 2007). I Guideline is hardness-dependent: 0.001 mg/L at hardness = 0 to 60 mg/L; 0.002 mg/L at hardness = 60 to 120 mg/L; 0.004 mg/L at hardness > 120 mg/L (CCME 2007). J Chronic guideline (AENV 1999). K Guideline is hardness-dependent: 0.025 mg/L at hardness = 0 to 60 mg/L; 0.065 mg/L at hardness = 60 to 120 mg/L; 0.11 mg/L at hardness = 120 to 180 mg/L; 0.15 mg/L at hardness > 180 mg/L (CCME 2007).


Table 5 (Cont’d.)

Water Quality Variable Units Regulatory

Guideline Detection

Limit Pit 24 Pit 25E Pit 44 Silkstone Fairfax Pit 24

(Hypo) Pit 24 (Epi)

Pit 25E (Hypo)

Pit 25E (Epi)

Pit 44 (Hypo)

Pit 44 (Epi)

Silkstone (Hypo)




Total Metals * * * * * * * * * Aluminum mg/L 0.1E 0.002 0.0137 0.0371 0.0887 0.0223 0.00288 * * * * * * * * * 0.00784 0.0104 0.0119 0.00369 Antimony mg/L 0.000001 0.0000864 0.000168 0.000141 0.0000927 0.0000282 * * * * * * * * * 0.0000853 0.0000935 0.000141 0.0000255 Arsenic mg/L 0.005 0.00004 0.00102 0.000317 0.00046 0.00515 0.000479 * * * * * * * * * 0.000887 0.00133 0.000366 0.000389 Barium mg/L 0.0001 0.101 0.0837 0.0853 0.226 0.055 * * * * * * * * * 0.0776 0.137 0.0788 0.0445 Beryllium mg/L 0.00001 <0.000003 0.0000064 <0.000003 0.0000061 <0.000003 * * * * * * * * * 0.0000059 0.0000037 0.0000136 0.0000066 Bismuth mg/L 0.00001 <0.000001 <0.000001 <0.000001 <0.000001 0.0000112 * * * * * * * * * <0.000001 <0.000001 <0.000001 <0.000001 Boron mg/L 0.0008 0.0268 0.0481 0.055 0.0616 0.00561 * * * * * * * * * 0.0252 0.0317 0.0519 0.0125 Cadmium mg/L F 0.000006 0.0000055 0.0000351 0.0000278 0.0000091 0.0000033 * * * * * * * * * 0.0000038 0.0000025 0.0000353 <0.000002 Calcium mg/L 0.1 25 110 73.4 50.4 19.8 * * * * * * * * * 22.3 32.2 108 19.4 Chlorine mg/L 0.5 0.3 <0.1 0.284 0.218 0.755 0.149 * * * * * * * * * <0.1 0.155 0.32 0.208 Chromium mg/L 0.001G 0.0003 0.0000749 0.000031 0.000113 0.000133 0.0000365 * * * * * * * * * 0.0000656 0.0000492 <0.00003 <0.00003 Cobalt mg/L 0.00001 0.0000549 0.000179 0.000508 0.00105 0.0000293 * * * * * * * * * 0.0000199 0.000187 0.000863 0.0000163 Copper mg/L 0.002H 0.0001 0.000273 0.000742 0.00137 0.000405 0.0000912 * * * * * * * * * 0.000396 0.000225 0.000702 0.000116 Iron mg/L 0.3 0.004 0.00721 <0.002 0.028 0.175 0.419 * * * * * * * * * <0.002 0.0474 0.0199 0.0928 Lead mg/L 0.001I 0.00001 0.0000061 0.0000226 0.0000431 0.0000476 0.0000072 * * * * * * * * * 0.0000188 0.000021 0.0000217 0.0000091 Lithium mg/L 0.0002 0.00563 0.0299 0.0301 0.0188 0.002 * * * * * * * * * 0.00601 0.00883 0.0444 0.00409 Manganese mg/L 0.00003 0.187 0.173 0.254 1.77 0.664 * * * * * * * * * 0.00258 1.31 0.681 0.039 Mercury mg/L 0.013J, 0.005 0.00005 <0.00001 <0.00001 <0.00001 <0.00001 <0.00001 * * * * * * * * * <0.00001 0.0000208 <0.00001 <0.00001 Molybdenum mg/L 0.073 0.000008 0.00165 0.00285 0.0108 0.002 0.000417 * * * * * * * * * 0.002 0.00055 0.00278 0.000384 Nickel mg/L 0.025K 0.00006 0.000435 0.00264 0.00347 0.00176 <0.000005 * * * * * * * * * 0.000292 0.000311 0.00437 <0.000005 Selenium mg/L 0.001 0.0003 0.000255 0.000675 0.000641 0.000272 <0.0001 * * * * * * * * * 0.000279 0.000177 0.000642 <0.0001 Silver mg/L 0.0001 0.000005 0.0000008 0.0000077 0.0000012 0.0000031 <0.0000005 * * * * * * * * * 0.0000011 <0.0000005 <0.0000005 <0.0000005Strontium mg/L 0.000008 0.515 2.05 1.48 1.48 0.123 * * * * * * * * * 0.432 0.621 2 0.129 Sulphur mg/L 0.6 20.7 196 55.4 43.4 0.556 * * * * * * * * * 18.2 18.4 154 0.483 Thallium mg/L 0.0008 0.000003 0.0000025 0.0000105 0.0000058 <0.0000003 0.0000122 * * * * * * * * * 0.0000028 0.0000007 0.0000171 <0.0000003Thorium mg/L 0.00003 0.0000025 0.0000079 0.000008 0.0000063 0.000022 * * * * * * * * * 0.0000023 0.0000078 0.000003 <0.0000003Tin mg/L 0.00007 <0.00003 <0.00003 <0.00003 <0.00003 <0.00003 * * * * * * * * * <0.00003 <0.00003 <0.00003 <0.00003 Titanium mg/L 0.00007 0.00109 0.00138 0.00249 0.0024 0.000684 * * * * * * * * * 0.000181 0.00152 0.000946 0.000244 Uranium mg/L 0.000003 0.00123 0.00522 0.00194 0.00107 0.0000389 * * * * * * * * * 0.00121 0.00112 0.00587 0.0000426 Vanadium mg/L 0.00005 0.000246 0.000219 0.000191 0.000692 0.0000415 * * * * * * * * * 0.000221 0.000383 0.0001 0.0000143 Zinc mg/L 0.03 0.0002 0.000521 0.00231 0.00393 0.00187 0.00147 * * * * * * * * * 0.00256 0.000812 0.00219 0.000651 Trace Mercury ng/L 13 0.6 1 2.9 1.3 5.4 3.4 * * * * * * * * * <0.6 7.3 4 1.5 Bold Below detection limit. XXX Guideline exceedance. * Metals were not analyzed in October. 1 Guidelines are Alberta Environment (1999) unless otherwise specified. A at pH 8.0, 10°C (CCME 2007). B CCME guideline for nitrate is 13 mg/L; CCME guideline for nitrite is 0.060 mg/L. C CCME (2007). AENV (1999) guideline: "To be in the range of 6.5 to 8.5 but not altered by more than 0.5 pH units from background”. D Guideline is for chronic total (inorganic and organic) phosphorus. E at pH>=6.5; [Ca2+]>=4 mg/L; DOC>=2 mg/L (CCME 2007). F Is equal to 10(0.86*LOG(Hardness)-3.2) (CCME 2007). G Guideline for chromium III is 0.0089 mg/L; guideline for chromium VI is 0.0010 mg/L (CCME 2007). Most stringent guideline (0.0010 mg/L) is used. H Guideline is hardness-dependent: 0.002 mg/L at hardness = 0 to 120 mg/L; 0.003 mg/L at hardness = 120 to 180 mg/L; 0.004 mg/L at hardness > 180 mg/L (CCME 2007). I Guideline is hardness-dependent: 0.001 mg/L at hardness = 0 to 60 mg/L; 0.002 mg/L at hardness = 60 to 120 mg/L; 0.004 mg/L at hardness > 120 mg/L (CCME 2007). J Chronic guideline (AENV 1999). K Guideline is hardness-dependent: 0.025 mg/L at hardness = 0 to 60 mg/L; 0.065 mg/L at hardness = 60 to 120 mg/L; 0.11 mg/L at hardness = 120 to 180 mg/L; 0.15 mg/L at hardness > 180 mg/L (CCME 2007).


Table 6 Changes in concentrations of water quality variables in Pit 24 (Stirling) Lake.

Water Quality Variable1 Units October 1998 September 2006 October 2010 February 2011

Epi. Hypo. Epi. Hypo. Epi. Hypo. Epi. Hypo. Alkalinity, total mg/L 213 336 183 313 187 253 208 312 Ammonia-N mg/L <0.05 0.26 0.05 0.64 <0.050 <0.050 <0.05 0.851 Bicarbonate mg/L 245 410 211 382 214 292 251 380 Calcium mg/L 16.8 23.7 18.7 37.9 19.4 29.3 22.2 33.2 Carbonate mg/L 7 <5 6 5 7 8.6 <5 <5 Chloride mg/L 0.7 2.3 1 1 <0.50 <0.50 <0.5 <0.5 Hardness mg/L 77 97 83 148 86 120 95.9 131 Magnesium mg/L 8.5 9.3 8.7 13 9.13 11.4 9.82 11.8 Nitrate-Nitrite mg/L <0.05 <0.05 0.1 0.1 <0.071 <0.071 <0.071 <0.071 pH pH units 8.6 7.9 8.6 8.3 8.55 8.52 8.32 8.09 Phosphorus, total mg/L 0.006 0.06 0.02 0.24 0.0073 0.0129 0.0109 0.279 Phosphorus, total dissolved mg/L 0.005 0.049 - - 0.0013 0.0059 0.0079 0.237 Potassium mg/L 3.1 3.3 2.7 3.3 2.4 2.67 2.91 3.2 Sodium mg/L 125 156 71 110 60.5 76.8 69.6 91.9 Sulphate mg/L 111 139 54.2 67.5 47.2 55.7 53.8 47.6 Total dissolved solids mg/L 393 536 265 421 266 347 281 397 Total Kjeldahl nitrogen mg/L 0.4 0.6 0.2 1.4 0.23 0.23 0.34 1.28 Total suspended solids mg/L 4 2 3 5 <3.0 <3.0 <3 3 Turbidity mg/L 1.9 2.4 0.4 40 - - - - Aluminum mg/L 0.19 0.13 0.0361 0.0122 - - 0.00784 0.0104 Arsenic mg/L <0.001 <0.001 0.000868 0.00196 - - 0.000887 0.00133 Barium mg/L 0.0541 0.35 0.0706 0.141 - - 0.0776 0.137 Boron mg/L 0.027 0.087 0.0228 0.327 - - 0.0252 0.0317 Iron mg/L 0.18 0.37 0.0155 0.0829 - - <0.002 0.0474 Manganese mg/L 0.0057 1.01 0.00504 0.992 - - 0.00258 1.31 Strontium mg/L 0.323 1.5 0.365 0.647 - - 0.432 0.621 Zinc mg/L 0.074 0.053 0.0057 0.00387 - - 0.00256 0.000812

1 Only water quality variable that were sampled in at least two of the three years indicated are included in the table.


4.0 DISCUSSION OF RESULTS 4.1 WATER QUALITY AND THE ECOLOGICAL VIABILITY OF END-PIT

LAKES

There have now been three sets of limnological and ecological studies conducted on CVM end-pit lakes: the studies in the 1990s conducted on Lovett, Silkstone, and Stirling (Pit 24) lakes (Agbeti 1998, Mackay 1999); the 2006 studies conducted on Lovett, Silkstone, and Stirling (Pit 24) lakes plus Pit 35 and Pit 45 lakes (Hatfield 2008), and the current study.

Taken together, the results of these studies indicate that there may be fewer constraints of water quality to the ecological viability of end-pit lakes in the CVM area than those described in End-Pit Lake Working Group (2004):

1. The concentration of a number of water quality variables, such as nutrients and major ions, are higher in end-pit lakes than in natural lakes, but these higher concentrations are not at levels that would affect the ecological viability of the end-pit lakes.

2. There have been relatively few instances of measured water quality variables, including metals, exceeding provincial or federal water quality guidelines.

3. The incidence of water quality guideline exceedance is not measurably greater in end-pit lakes than in natural lakes in the CVM area.

4. The trophic status of end-pit lakes is similar to that of natural lakes in the CVM area.

The exception to this is dissolved oxygen. The results of this study indicate there are portions of end-pit lakes in all seasons sampled with concentrations of dissolved oxygen that are below provincial guidelines for the protection of aquatic life (Figure 3). The same is true of Fairfax Lake, the natural lake that was surveyed as part of this study (Figure 3). The depth patterns of dissolved oxygen in the lakes that were studied (Figure 3) are related to processes of lake stratification and turnover.

4.2 LAKE STRATIFICATION AND TURNOVER

4.2.1 Patterns of Lake Stratification and Turnover in Lakes in the CVM Area

Patterns of lake stratification and turnover are inconsistent among the end-pit lakes in the CVM area. Early studies (Agbeti 1998, Mackay 1999) suggested that Lovett Lake and Pit 24 (Stirling) Lake stratified in the summer and experienced either complete mixing or weak stratification at greater depths in the fall. Hatfield (2008) found that Lovett Lake and Pit 24 exhibited thermoclines, oxyclines and chemoclines throughout the summer and fall and suggested they did not experience fall turnover. In addition, Hatfield (2008) suggested that Silkstone and Pit 45 lakes did not experience fall turnover, and the results of this study indicate Silkstone, Lovett and Pit 45, and Pit 24 lakes were stratified with at best incomplete turnover. All studies found that Fairfax Lake experienced fall turnover.


4.2.2 Importance of Salinity of Water Inflows to End-Pit Lakes

Figure 6 indicates that the end-pit lakes in the CVM area receive water from both surface water and groundwater sources. The results of the Hatfield (2008) study and this study identify the presence of higher salinity groundwater as a contributing factor as to whether an end-pit lake will become meromictic. Inflow of higher salinity groundwater coupled with inflow of lower salinity surface water sets up the conditions for a chemocline to form, increasing the probability that a lake will not turn over but will instead remain stratified.

While the current study indicated partial turnover occurred in some of the end-pit lakes, only the lakes that had no chemocline turned over in fall 2010 (Fairfax, Pit 35, Pit 142, and Pit 25S lakes). The other six lakes that were studied, Pit 25E, Lovett, Silkstone, Pit 24 (Stirling), Pit 44, and Pit 45 lakes, had a definite chemocline during much of the sampling period in 2010 and either remained stratified or had only incomplete or partial turnover.

4.2.3 Importance of Lake Depth

The results of this study indicate that shallow end-pit lakes have a greater likelihood of being holomictic. Pit 35, Pit 142, Pit 25S and Fairfax lakes were holomictic in 2010 and these four lakes have four of the five shallowest mean depths and the four shallowest maximum depths of any of the lakes sampled in this study (Figure 5).

4.2.4 Relative Importance of the Salinity of Inflow Water and Lake Depth

As indicated above, the same four lakes that had no chemocline and turned over in fall 2010 – Pit 35, Pit 142, Pit 25S and Fairfax lakes – were also the lakes that were among the shallowest lakes that were studied. While lake depth is important, the relative salinity of (any) surface and groundwater inflows is also important. For example, the surface salinity of Pit 25S Lake was the highest of any lake studied, much higher than any of the other three lakes that had no chemocline and exhibited turnover in fall 2010 (Figure 5). It may be that the reason why Pit 25S Lake exhibited no chemocline and exhibited turnover is because the salinity of surface inflows to the lake were sufficiently similar to the salinity of groundwater inflows to the lake such that a salinity gradient could not be created. The relative importance of lake depth and salinity of inflows for Pit 25S Lake is uncertain and, given the current data and information available on end-pit lakes in the CVM area, it is uncertain whether: (i) deeper end-pit lakes with surface and groundwater inflows that have similar salinities would not form chemoclines and would turnover; or (ii) shallower end-pit lakes with a large difference in salinity of surface and groundwater inflows would form chemoclines and permanently stratify.

It should be noted that salinity of groundwater in the CVM area varies widely; MEMS (2008) reported that the concentration of total dissolved solids in groundwater in the CVM area varied from 119 mg/L to 1,330 mg/L. The spatial variability of groundwater salinity may be such that the ability to control the salinity of inputs to end-pit lakes may be limited.


4.2.5 Do Stratification and Lake Turnover Matter?

As indicated above: (i) dissolved oxygen concentrations may be the most significant water quality issue related to the ecological viability of end-pit lakes in the CVM area; (ii) the concentrations of dissolved oxygen are a function of the pattern and degree of lake stratification and turnover; and (iii) these are in turn determined by a number of factors, with lake depth and salinity of water inflows being two of the most important.

Figure 7 indicates the percentage of lake volume that was at a given dissolved oxygen concentration or greater for each of the sampling periods. Of the lakes with bathymetric maps in an electronic format that could be used in this analysis, three exhibited no chemoclines in 2010 and experienced fall turnover – Pit 35, Pit 142, and Pit 25S lakes, while five did exhibit chemoclines in 2010 and did not experience fall turnover – Pit 25E, Pit 44, Silkstone, Lovett and Pit 45 lakes.

With the exception of Pit 25E Lake, the percent of the total lake volume with a concentration of dissolved oxygen that was greater than the Alberta Environment chronic guideline for protection of aquatic life was similar for all lakes within the 2010 sampling periods: 75% or greater in July 2010; 75% or greater in August 2010; 80% in September 2010; 80% in October 2010; and 0% (for all lakes) in February 2011 (Figure 7)5. Results from the June 2011 sampling period were variable with Pit 25E and 25S at 0%, Lovett and Silkstone at 60% or greater and Pit 45, Pit 34, Pit 44 and Pit 142 at 80% or greater. The relative amount of aquatic habitat, as defined by the concentration of dissolved oxygen (in the context of this water quality study) is similar across most end-pit lakes and across seasons irrespective of whether or not chemoclines existed and whether or not the lakes exhibited turnover.

The exception to this is Pit 25E Lake. Pit 25E Lake has one of the highest differences in salinity between surface water (epilimnion) and water at lower levels (hypolimnion) (Figure 5) and also had a chemocline that began relatively close to the surface in 2010 (i.e., less than three m depth).

While these results are preliminary, they do suggest that the effects of chemoclines in end-pit lakes on water quality, particularly dissolved oxygen concentrations, and the consequent inability for end-pit lakes to turnover, may be less than initially thought, and the ability of end-pit lakes be holomictic may be less of an factor in determining amount of viable aquatic habitat than previous studies have indicated (End-Pit Lake Working Group 2004, Hatfield 2008).

5 Available habitat was defined as the volume of water with a dissolved oxygen concentration greater than 6.5 mg/L.

Although many species of fish are able to survive in concentrations much lower, 6.5mg/L is defined as the lower chronic limit by Alberta Environment (1999).


Figure 7 Relationship between end-pit lake volume and dissolved oxygen concentrations.

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Note: Water quality depth profile not collected on Silkstone Lake in February 2011 due to unsafe ice conditions


4.3 COMPARISON WITH END-PIT LAKE DEVELOPMENT GUIDELINES

A comparison of existing end-pit lakes at Coal Valley to the guidelines for end-pit lake development at coal mine operations (End-Pit Lake Working Group 2004) in Hatfield (2008) is presented in Table 1 of this report. Table 7 presents a similar comparison for hydrological and chemical factors, updated to the current study. Water quality characteristics, stratification and lake turnover were screened against Fairfax Lake for each of the relevant guidelines.

As observed in previous studies, end-pit lake water quality was similar to Fairfax Lake. Water quality across all end-pit lakes had very few guideline exceedances in 2010 and is considered of good quality with respect to aquatic life. End-pit lake epilimnion water quality and trophic status were similar to Fairfax Lake with the main difference being the stratification between the epilimnion and hypolimnion layers in meromictic end-pit lakes. While the water quality of end-pit lake hypolimnia is of generally good quality, dissolved oxygen, temperature, pH, conductivity and total dissolved solids were different than epilimnion waters in most of the lakes sampled in this study. While historical results (Hatfield 2008) indicate that permanent stratification in meromictic end-pit lakes likely limits fish habitat to the epilimnion and can restrict fish and other aquatic organism to habitat found in this water layer, the results of this study suggest that this may not be a major water quality issue with respect to the relative amount of suitable habitat for aquatic life in most end-pit lakes.


Table 7 Assessment of end-pit lakes against lake development criteria and the natural Fairfax Lake.

Design Factors1 Indicators1 Parameter1 Fairfax

Lake Pit 35 Silkstone Lake Pit 45

Stirling Lake

(Pit 24) Lovett Lake Pit 44 Pit 25E Pit 25S Pit 142

Hydrological

Inlet Presence/ absence Absence Absence Presence Presence Absence Absence Absence Presence Presence3 Absence

Outlet Presence/ absence Presence Presence Presence Presence Absence Presence2 Presence Presence Presence Absence

Sediment Yield-Erosion

Total suspended

solids

Within range

(3-5 mg/L)

Not sampled

Within range

(3-5 mg/L)

Not sampled

Within range

(3-5 mg/L)

Within range

(3-5 mg/L) < 3 mg/L < 3 mg/L Not

sampled Not

sampled

Chemical

Toxic Substances

Water guideline

exceedances iron none

Phenols, phosphorus,

chlorine, arsenic

Phenols, phosphorus4 none Phenols none none none

Overturn Summer

stratification Presence Presence Presence Presence Presence Presence Presence Presence Presence Presence

Fall mixing Presence Presence Absence Partial Absence Absence Absence Absence Presence Presence

1 From End-Pit Lake Working Group (2004). 2 Subsurface outflow is present (spring that feeds the Lovett River). 3 Observed groundwater inflow above lake surface. 4 Sampled at depth. Note: End-pit lake assessments were reported based on comparisons with Fairfax Lake characteristics. Total suspended solids and guideline exceedances are shown as a project average.


5.0 CONCLUSIONS

This study is the third examination of water quality in end-pit lakes in the Coal Valley area. These studies suggest that there may be fewer constraints of water quality on the ecological viability of end-pit lakes in the Coal Valley area than those described in End-Pit Lake Working Group (2004):

1. The concentration of a number of water quality variables, such as nutrients and major ions, are higher in end-pit lakes than in natural lakes, but these higher concentrations are not at levels that would affect the ecological viability of the end-pit lakes.

2. There have been relatively few instances of measured water quality variables, including metals, exceeding provincial or federal water quality guidelines.

3. The incidence of water quality guideline exceedance is not measurably greater in end-pit lakes than in natural lakes in the CVM area.

4. The trophic status of end-pit lakes is similar to that of natural lakes in the CVM area.

The results of this study suggest that the effects of chemoclines in end-pit lakes on water quality, particularly dissolved oxygen concentrations, and the consequent inability for end-pit lakes to turnover, may be less than initially thought, and the ability of end-pit lakes be holomictic may be less of an factor in determining amount of viable aquatic habitat than previous studies have indicated. It is worth noting that, while lake turnover is generally considered an important ecological process in most productive lakes (Hutchinson 1938, Effler and Perkins 1987 and Wetzel 2001) it is not a necessary process governing the ability of a lake to sustain healthy fish populations (Effler and Perkins 1987, Trimbee and Prepas 1988).


6.0 REFERENCES

Agbeti, M.D. 1998. Water quality of two end-pit lakes in relation to fishery sustainability. Prepared for: Luscar Ltd. Prepared by: Bio-Limno Research & Consulting. 80 pp.

Alberta Environment. 1999. Surface Water quality guidelines for use in Alberta. Accessed at http://environment.gov.ab.ca/info/library/5713.pdf

Anderson, M.T. and C.L. Hawkes. 1985. Water chemistry of Northern Great Plains strip mine and livestock water impoundments. Water Resources Bulletin 21: 499-505.

Castro, J.M. and J.N. Moore. 2001. Pit lakes: their characteristics and the potential for their remediation. Environmental Geology 39: 1254-1260.

CCME (Canadian Council of Ministers of the Environment). 2007. Canadian Environmental Quality Guidelines. Canadian Council of Ministers of the Environment. Winnipeg. Manitoba.

Effler, S.W and W.G. Perkins. 1987. Failure of Spring Turnover in Onondaga Lake, NY. Water, Air, and Soil Pollution, 34: 285-291.

End-Pit Lake Working Group 2004. Guidelines for Lake Development at Coal Mine Operations in Mountain Foothills of the Northern East Slopes, Report # ESD/LM/00-1, Alberta Environment, Environmental Service.

Hatfield 2008. Coal Valley Mine: An Evaluation of Existing End-Pit Lakes. Prepared for Coal Valley Resources Inc. Prepared by: Hatfield Consultants. 42pp + Appendices.

Hutchinson, G.E., 1938. On the relationship between the oxygen deficit and the productivity and topology of lakes. Int. Rev. Hydroiol. 36: 336-355.

Lewis, W.M., Jr. 1983. A revised classification of lakes based on mixing. Can. J. Fish . Aquat. Sci. 40: 1779-1797.

Luscar Ltd, 1994. Development of sport fisheries in lakes created by coal mining operations in the eastern slopes. 151 pp.

Mackay, W.C. 1999. Coal Valley Mine Extension: Cumulative effects of reclaimed end-pit lakes on water quality and fisheries resources. Prepared for: Luscar Ltd. Prepared by: W.C. Mackay & Associates. 39 pp.

MEMS (Millennium EMS Solutions). 2008. Hydrogeology EIA: Mercoal West and Yellowhead Tower. Prepared by Millennium EMS Solutions Ltd. for Coal Valley Resources Inc.

http://environment.gov.ab.ca/info/library/5713.pdf�


Patterson, J.C. and P.F. Hamblin. 1988. Thermal simulation of a lake with winter ice cover. Limnol. Oceanogr. 33: 323-338.

Reynolds, J.B. 1997. Ecology of overwintering fishes in Alaskan Freshwater. Pages 281-302 in A.M. Milner and M.W. Oswood, editors. Freshwaters of Alaska: ecological synthesis. Springer Verlag, New York.

Trimbee, A.M. and E.E. Prepas. 1988. Dependence of lake oxygen depletion rates on maximum oxygen storage in a partially meromictic lake in Alberta. Can. J. Fish. Aquat. Sci. 45:571-576.

Wetzel, R.G. 2001. Limnology: Lake and River Ecosystems. Third Edition. Academic Press, San Diego, California. 1006 pp.


7.0 CLOSURE

We trust the above information meets your requirements. If you have any questions or comments, please contact the undersigned.

HATFIELD CONSULTANTS:

Approved by:

September 8, 2011

Colin Schwindt Project Manager

Date

Approved by:

September 8, 2011

Peter McNamee Project Director

Date

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APPENDICES

Appendix A1

Chemical Design Factors for End-Pit Lakes (from End-Pit

Lakes Working Group [2004])

Coal Valley Mine: An Evaluation of Water Quality A1-1 Hatfield In Existing End-Pit Lakes

A1.0 CHEMICAL DESIGN FACTORS FOR END-PIT LAKES

The following tables are the chemical design factors for end-pit lakes contained in End-Pit Lakes Working Group (2004).


Table A1.1 Chemical design factors for a self-sustaining native salmonid end pit-lake.

Design Factor CHEMICAL

Relative Importance

Degree of Control

Parameter Ranges and Probability of Success

High Medium Low

Water Quality (pH, alkalinity, dissolved oxygen, temperature, suspended solids, turbidity, TDS, major ions, nutrients, metals)

High Variable Close to median water quality values of natural water bodies in the region

Within the range of values for natural water bodies in the region

At the extreme, or outside of the range for natural water bodies in the region

Importance/Relevance • natural water bodies exhibit a wide variation in general water quality • end pit lakes with water quality that is within the general range of

natural variation for the region have a higher chance of supporting a viable ecosystem than those outside of regional variation

• acceptable water quality is essential in supporting aquatic life

Design Considerations • evaluate the anticipated water quality (surface and groundwater) to see if

there are any water quality characteristics that may adversely affect aquatic biota and long-term ecosystem function

• examine possible measures to improve water quality for any parameters that may be of concern

• maximize flow of surface water through lake

Potential Toxic Substances High Variable Meets water quality guidelines

Slightly exceeds guidelines

Significantly exceeds guidelines

Importance/Relevance • potentially toxic substances (e.g. some metals, salinity, H2S)

may seriously compromise the ability of an end pit lake to meet its intended objective of supporting fisheries

• substances that accumulate (e.g. Se, Hg) in aquatic biota may have detrimental effects (e.g. on biota, food webs and human consumption of fish)

Design Considerations • end pit lakes should meet the Surface Water Quality Guidelines for

Use in Alberta (AENV 1999 as amended) or other applicable guidelines for parameters not specifically addressed in Alberta’s guidelines

• if guidelines are exceeded, further investigations to evaluate the source, fate and effect of a particular parameter are required

• known geological sources (e.g. overburden) of toxic substances should be selectively handled to reduce the chances of having them contact lake water

• toxic substances should not be placed in end pit lakes


Table A1.2 Optimum lake characteristics of a self-sustaining native salmonid end pit-lake.

Parameter Optimal Condition

Water level • Fluctuations up to 1 metre are beneficial

Area • Increase surface area to volume ratio to promote productivity

• Connectivity to adjacent lakes and the natural watershed is important.

Depth • The deepest part of the lake should be in the range of 25 m for dragline lakes and 75 m for truck and shovel lakes.

• Mean depth should be 10 to 15 5 metres

Bank slope • Shore slopes should range from 2H:1V to 5H:1V

Shoreline • Long and irregular shorelines provide habitat diversity for fish and wildlife and minimize erosion due to wave action.

Littoral zone • 20% to 40% of the total lake area to maximize productivity, irregular surface to provide microsite diversity of habitat and shelter for fish

Bottom configuration • Irregular bottom in the littoral zone is important for habitat diversity at depths less than 6 m

Substrate • Variation in size and compaction to provide variable benthic habitat.

• Organic soil and boulders in the littoral zone to promote vegetation establishment and growth

• Suitable sized substrate for spawning in inlet and outlet channel.

Lake orientation • Exposed and parallel to prevailing wind direction to promote mixing of the water column

Water quality • Conform to the current Surface Water Quality Guidelines for Use in Alberta

• Water quality should not pose limitations to aquatic organisms

Inlet/outlet channels • Maintenance free inlet and outlet that provide spawning habitat

• Vegetation or some other structure that provides overhead cover

Public access • Access should be stable and safe

Safety • No unusual dangers

• Visible signage

Biological diversity • Comparable biological diversity to other lakes in the region


Table A1.3 Potential water quality monitoring parameters for a self-sustaining native salmonid end pit-lake.

• Dissolved oxygen (DO) (seasonal and winter) • Temperature • Conductivity • Total dissolved solids (TDS) • Major ions (routine analysis) • pH • Alkalinity • Total Suspended Solids (TSS) • Turbidity • Nitrogen (nitrate + nitrite, ammonia, Kjeldahl) • Phosphorus (dissolved, total) • Chlorophyll a • Sulphides • Metals, metalloids • Organic compounds if warranted • Toxicity (acute, chronic) if warranted • Microbiological parameters if warranted


Table A1.4 Potential evaluation/performance assessment criteria for a self-sustaining native salmonid end pit-lake.

Design Factors Indicators Parameters to be measured Targets/Goals

Chemical

Toxic substances • Water chemistry • Tissue concentrations in biota if warranted

• Surface Water quality guidelines for aquatic life used in Alberta.

• Background comparison to other lakes in region

Overturn (mixing) • Summer stratification • Fall mixing

• Presence of annual summer stratification and fall turnover

Water quality • Water chemistry of groundwater leaving lake in discharge areas

• Water chemistry in lake and discharge

• Meet Surface Water Quality Guidelines used in Alberta

• Chemical end points fall within regional range

Appendix A2

Bathymetric Maps

!

!

ALBERTA

CALGARY

EDMONTON

519250

519250

519500

519500

519750

519750

520000

520000

5876

500

5876

500

5876

750

5876

750

5877

000

5877

000

5877

250

5877

250

t

Mapped Area = 66058 m2

Mapped Volume = 323800 m3

Average Depth = 5.5 mMaximum Depth = 18 mContour intervals in meters.

K:\Data\Project\MEMS1648\_MXD\MEMS1648_Lovette1_20110811.mxd

Figure A2.1 Bathymetric map of Lovett Lake.

120 0 12060 m

Projection: NAD83 UTM Zone 11N1:6,000Scale:

Outflow Seepage

Depth Scale (m)0 - 11 - 22 - 33 - 44 - 55 - 66 - 77 - 88 - 99 - 1010 - 1111 - 1212 - 1313 - 1414 - 1515 - 1616 - 1717 - 1818 - 1919 - 20

Rge 19

Twp 47

$

!

!

ALBERTA

CALGARY

EDMONTON

518750

518750

519000

519000

519250

519250

519500

519500

5876

750

5876

750

5877

000

5877

000

5877

250

5877

250

5877

500

5877

500

t



Average Depth = 4.7 mMaximum Depth = 14.8 mContour intervals in meters.

K:\Data\Project\MEMS1648\_MXD\MEMS1648_Silkstone_20110811.mxd

Figure A2.2 Bathymetric map of Silkstone Lake.

120 0 12060 m


Outflow

Inflow

$

$Rge 19

Twp 47

Depth Scale (m)0 - 11 - 22 - 33 - 44 - 55 - 66 - 77 - 88 - 99 - 1010 - 1111 - 1212 - 1313 - 1414 - 1515 - 1616 - 1717 - 1818 - 1919 - 20

!

!

ALBERTA

CALGARY

EDMONTON

519000

519000

519250

519250

5875

500

5875

500

5875

750

5875

750

t




K:\Data\Project\MEMS1648\_MXD\MEMS1648_Pit24_20110811.mxd

Figure A2.3 Bathymetric map of Pit 24 (Stirling) Lake.

60 0 6030 m


Depth Scale (m)0 - 11 - 22 - 33 - 44 - 55 - 66 - 77 - 88 - 99 - 1010 - 1111 - 1212 - 1313 - 1414 - 1515 - 1616 - 1717 - 1818 - 1919 - 20

Rge 19

Twp 47

!

!

ALBERTA

CALGARY

EDMONTON

523500

523500

523750

523750

5871

250

5871

250

5871

500

5871

500

5871

750

5871

750

t





Figure A2.4 Bathymetric map of Pit 35 Lake.

75 0 7537.5 m


Depth Scale (m)0 - 11 - 22 - 33 - 44 - 55 - 66 - 77 - 88 - 99 - 1010 - 1111 - 1212 - 1313 - 1414 - 1515 - 1616 - 1717 - 1818 - 1919 - 20

Rge 19

Twp 46

!

!

ALBERTA

CALGARY

EDMONTON

523500

523500

523750

523750

524000

524000

524250

524250

5871

000

5871

000

5871

250

5871

250

5871

500

5871

500

5871

750

5871

750

5872

000

5872

000

t






125 0 12562.5 m


Outflow

Rge 19

Twp 46

Depth Scale (m)0 - 11 - 22 - 33 - 44 - 55 - 66 - 77 - 88 - 99 - 1010 - 1111 - 1212 - 1313 - 1414 - 1515 - 1616 - 1717 - 1818 - 1919 - 20

$

!

!

ALBERTA

CALGARY

EDMONTON

504000

504000

504500

504500

5880

600

5880

600

5880

900

5880

900

t






100 0 10050 m


Depth Scale (m)0 - 11 - 22 - 33 - 44 - 55 - 66 - 77 - 88 - 99 - 1010 - 1111 - 1212 - 1313 - 1414 - 1515 - 1616 - 1717 - 1818 - 1919 - 20

Rge 21

Twp 47

!

!

ALBERTA

CALGARY

EDMONTON

522250

522250

522500

522500

522750

522750

5871

750

5871

750

5872

000

5872

000

5872

250

5872

250

t




K:\Data\Project\MEMS1648\_MXD\MEMS1648_Pit25E_20110811.mxd

Figure A2.7 Bathymetric map of Pit 25E Lake.

80 0 8040 m


Outflow

InflowDepth Scale (m)

0 - 11 - 22 - 33 - 44 - 55 - 66 - 77 - 88 - 99 - 1010 - 1111 - 1212 - 1313 - 1414 - 1515 - 1616 - 1717 - 1818 - 1919 - 20

Rge 19

Twp 46

$

$

!

!

ALBERTA

CALGARY

EDMONTON

520400

520400

520800

520800

5873

000

5873

000

5873

500

5873

500

t




K:\Data\Project\MEMS1648\_MXD\MEMS1648_Pit25S_20110816.mxd

Figure A2.8 Bathymetric map of Pit 25S Lake.


100 0 10050 m

Outflow

Depth Scale (m)0 - 11 - 22 - 33 - 44 - 55 - 66 - 77 - 88 - 99 - 1010 - 1111 - 1212 - 1313 - 1414 - 1515 - 1616 - 1717 - 1818 - 1919 - 20 $

Rge 19

Twp 46

!

!

ALBERTA

CALGARY

EDMONTON

523000

523000

523250

523250

523500

523500

5872

500

5872

500

5872

750

5872

750

5873

000

5873

000

t






80 0 8040 m


Rge 19

Twp 47

Depth Scale (m)0 - 11 - 22 - 33 - 44 - 55 - 66 - 77 - 88 - 99 - 1010 - 1111 - 1212 - 1313 - 1414 - 1515 - 1616 - 1717 - 1818 - 1919 - 20

!

!

ALBERTA

CALGARY

EDMONTON

527750

527750

528000

528000

528250

528250

528500

528500

528750

528750

529000

529000

5868

500

5868

500

5868

750

5868

750

5869

000

5869

000

5869

250

5869

250

5869

500

5869

500

5869

750

5869

750

t




K:\Data\Project\MEMS1648\_MXD\MEMS1648_Fairfax_20110811.mxd

Figure A2.10 Bathymetric map of Fairfax Lake.

170 0 17085 m


Depth Scale (m)0 - 11 - 22 - 33 - 44 - 55 - 66 - 77 - 88 - 99 - 1010 - 1111 - 1212 - 1313 - 1414 - 1515 - 1616 - 1717 - 1818 - 1919 - 20

Rge 19

Twp 46

Outflow

$

coal valley robb trend - appendix 8 - end pit lake report · 2014. 11. 3. · suite 200 – 850...

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