Preliminary Mine Site Water
Management Plan
Sukunka Coal Mine Project
Prepared for:
Glencore
650 West Georgia Street
Suite 710, PO Box 11611
Vancouver, BC V6B 4N9
Attention: Bryan Tiedt
Prepared by:
Knight Piésold Ltd.
750 West Pender Street
Suite 1400
Vancouver, BC V6C 2T8
Final Rev. 01
123110482
June 28, 2015
PRELIMINARY MINE SITE WATER MANAGEMENT PLAN
Table of Contents
June 28, 2015
Table of Contents
ABBREVIATIONS ....................................................................................................................... III
1.0
1.1
1.2
1.3
1.4
INTRODUCTION ............................................................................................................. 1
PROJECT LOCATION ......................................................................................................... 1
PURPOSE AND SCOPE ...................................................................................................... 1
PERFORMANCE OBJECTIVES ........................................................................................... 1
REGULATORY FRAMEWORK ............................................................................................. 1
2.0
2.1
ENVIRONMENTAL CONSIDERATIONS ........................................................................... 1
HYDROMETEOROLOGY .................................................................................................... 2
2.1.1
Extreme Rainfall Events .................................................................................. 2
WATERSHEDS ...................................................................................................................... 4
2.2
3.0
3.1
3.2
3.3
ENVIRONMENT PROTECTION MEASURES ...................................................................... 4
WATER MANAGEMENT OBJECTIVES ............................................................................... 5
BEST MANAGEMENT PRACTICES...................................................................................... 5
3.2.1
Collection Ditches .......................................................................................... 6
3.2.2
Diversion Ditches............................................................................................. 6
3.2.3
Energy Dissipaters ........................................................................................... 6
3.2.4
Slope Drains ..................................................................................................... 6
3.2.5
Waterbars ........................................................................................................ 7
3.2.6
Temporary Diversion Structures..................................................................... 7
3.2.7
Sediment Basins and Sediment Control Ponds .......................................... 7
3.2.8
Flocculent Addition ........................................................................................ 7
WATER MANAGEMENT MEASURES .................................................................................. 8
3.3.1
Preliminary Mine Site Water Management Plan Overview ...................... 8
3.3.2
Description of Water Management Measures ........................................... 8
3.3.3
Water Management Design Elements ...................................................... 15
3.3.4
Water Management Measures by Project Phase.................................... 16
4.0
4.1
4.2
MONITORING PROGRAM ........................................................................................... 18
MONITORING ................................................................................................................... 18
FOLLOW-UP AND ADAPTIVE WATER MANAGEMENT STRATEGY ................................ 19
4.2.1
Flocculants Use to Aid Settling .................................................................... 19
5.0
REFERENCES................................................................................................................. 20
LIST OF TABLES
Table 2.1-1
Table 3.3-1
Table 3.3-2
Table 3.3-3
Table 3.3-4
Table 3.3-5
Intensity-Duration-Frequency Values ........................................................... 3
Catchment Areas of Key Water Management Features ....................... 15
Design Criteria ............................................................................................... 16
Construction Water Management Measures........................................... 17
Operations Water Management Measures ............................................. 17
Closure Water Management Measures .................................................... 18
i
PRELIMINARY MINE SITE WATER MANAGEMENT PLAN
Table of Contents
June 28, 2015
LIST OF FIGURES
Figure 3.3-1
Figure 3.3-2
Figure 3.3-3
Figure 3.3-4
Sukunka Project Layout ............................................................................... 10
North Collection Channel Typical Section In Rock Cut .......................... 12
North Collection Channel Typical Section In Overburden ..................... 13
North Collection Channel Typical Section In Fill....................................... 14
ii
PRELIMINARY MINE SITE WATER MANAGEMENT PLAN
Abbreviations
June 28, 2015
Abbreviations
BC
British Columbia
BMP
best management practice
CHPP
coal handling and processing plant
EC
Environment Canada
KPL
Knight Piésold Ltd.
LAA
local assessment area
masl
metres above sea level
MOE
Ministry of Environment
NSCP
North Sediment Control Pond
PDA
Project development area
PMP
probable maximum precipitation
SCP
sediment control pond
SSCP
South Sediment Control Pond
the Project
Sukunka Coal Mine Project
WMP
Water Management Plan
WSCP
West Sediment Control Pond
iii
PRELIMINARY MINE SITE WATER MANAGEMENT PLAN
Introduction
June 28, 2015
1.0
Introduction
1.1
PROJECT LOCATION
The Sukunka Coal Mine Project (the Project) is located southeast of the Sukunka River and
northwest of Bullmoose Creek, within the Peace River Regional District. The mine site is located
within the Skeeter Creek and Chamberlain Creek watersheds, which are tributaries of the
Sukunka River.
1.2
PURPOSE AND SCOPE
This report outlines the preliminary mine site Water Management Plan (WMP) for the Project to
support the environmental assessment application. The WMP includes information for the
construction, operations and closure phases of the Project. The WMP, and its components, will
inform the development of other Environmental Management Plans. This plan is submitted as
part of the environmental assessment and is preliminary. A more detailed plan will be submitted
as part of the Mines Act permit application.
1.3
PERFORMANCE OBJECTIVES
The WMP describes the ability of the site water management infrastructure to contain, control,
and convey runoff from snowmelt and rainfall, and in particular short duration extreme rainfall
events (e.g., 1 in 10 year rainfall or 1 in 200 year rainfall events). Water management facilities are
designed with two specific operating modes: 1) service conditions, which include day-to-day
operations and 2) ultimate limit conditions, which include provisions for safely handling runoff
during extreme hydrologic events.
1.4
REGULATORY FRAMEWORK
This WMP is designed to minimize project related effects to the receiving environment,
specifically receiving water bodies, and to meet commitments within the Application
Information Requirement (AIR) document. The WMP may be updated in the future to address
comments made during the environmental assessment review process, or to meet requirements
outlined in applicable permits.
2.0
Environmental Considerations
The Project is located in the Rocky Mountain Inner Foothills region. Topography in the region is
typified by high elevation (1,600 to 2,000 m) mountain ridges and peaks and steep-sided slopes
with relatively flat-bottomed valleys. The property is predominantly forested with lodgepole pine
and occasional spruce, with stands of balsam poplar occurring in the lower or wetter areas of
the property. Climate in the region is typified by cold temperatures and snowfall in the winter,
and warm temperatures and both frontal and convective rainfall in the summer.
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PRELIMINARY MINE SITE WATER MANAGEMENT PLAN
Environmental Considerations
June 28, 2015
Runoff from the project development area (PDA) will naturally want to flow downhill and into the
aquatic environment surrounding the Project, specifically Chamberlain Creek and Skeeter
Creek. In order to mitigate the potential for sediment entrainment or chemical loading to
compromise water quality as it passes through the PDA and into the surrounding aquatic
environment, best management practices (BMP) will be applied.
2.1
HYDROMETEOROLOGY
The Project is located in a rain shadow of easterly flowing Pacific air coming over the main Hart
Ranges of the Rocky Mountains, which creates a strong southwest to northeast precipitation
gradient perpendicular to the mountain range alignment. The region can also be affected by
low-pressure systems built up in central Alberta that can push considerable moisture westward
into the area, resulting in orographic uplift and producing greater volumes of precipitation and
runoff in higher elevation watersheds. Furthermore, cold dense Arctic air often stalls in the region
in the winter bringing periods of intense cold and considerable snowfall (Demarchi 2011).
Annual precipitation within the PDA varies strongly with elevation, and is estimated to range from
545 mm at low elevations (approximately 700 m) to 885 mm at high elevations (approximately
1,700 m). Annual runoff also varies with elevation, and it is estimated to range from approximately
226 to 550 mm between the elevations of 700 and 1,700 m. Hydrometeorological parameters are
based on the results of the Project baseline watershed model, which has been developed using
long-term synthetic precipitation and temperature records calibrated to long-term synthetic
streamflow records. More information is provided in the Watershed Model Report (KP 2014a).
The annual temporal distribution of runoff in the region is dominated by high flows during the
spring (May–June) snowmelt freshet, followed by low flows for much of the remainder of the
year, interspersed by periodic low to moderate magnitude rainfall-runoff events during the
summer and fall. Peak flows typically occur during the freshet or during convective storms in the
summer and fall, while low flows can occur either during the late summer or late winter. More
information regarding local and regional hydrologic characteristics is provided in the Baseline
Hydrology Report (KP 2014b).
2.1.1
Extreme Rainfall Events
Annual extreme 24-hr rainfall values are summarized in Table 2.1-1. Daily precipitation data
collected by Environment Canada (EC) at their Bullmoose Station between 1983 and 2002 were
used to develop the return period values by applying the Extreme Value Type 1 (Gumbel)
distribution to the data. This distribution may be expressed in the form of a frequency factor
equation, as follows:
X T = X + KT S
XT
= extreme event rainfall (mm)
= mean rainfall for return period (mm)
K T = frequency factor
S = standard deviation for return period (mm)
X
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PRELIMINARY MINE SITE WATER MANAGEMENT PLAN
Environmental Considerations
June 28, 2015
The daily values were initially adjusted to 24-hr values using a multiplier of 1.13 (Hershfield 1961),
before the data were scaled to the median site elevation of 1,200 m, from the Bullmoose Station
elevation of 1,100 m, using an orographic adjustment factor of 5 percent per 100 m. The
resultant values were checked against rainfall frequency information published by EC for
Chetwynd and scaled to the Project using the same 5% per 100 m orographic factor. Both sets
of values agree very well and are within 3 mm for all return periods presented below.
The 24-hr probable maximum precipitation (PMP) event for the Project site was estimated to be
375 mm. The Hershfield equation and the mean and standard deviation of the Bullmoose Station
24-hr precipitation data, scaled to 1,200 m, were used to determine an appropriate frequency
factor for use in the estimation of the PMP.
The possibility of snowmelt combined with extreme rainfall must be considered when
determining design flows.
Table 2.1-1
Intensity-Duration-Frequency Values
Return Period (years)
24 hour Rainfall (mm)
2
44
10
71
25
85
50
95
100
106
200
116
500
129
PMP
370
NOTES:
The PMP was derived using standard world meteorological organization procedures (Hershfield 1965) /
Hershfield Method. The PMP is effectively the largest conceivable storm event that could possible impact
the site.
The PMP value should be combined with an estimate of snowmelt when computing the probable
maximum flood (PMF).
Precipitation depths assume a median elevation of 1,200 m, which is the approximate mean elevation of
the PDA.
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PRELIMINARY MINE SITE WATER MANAGEMENT PLAN
Environment Protection Measures
June 28, 2015
2.2
WATERSHEDS
Surface conditions, topography, soil cover and vegetation are key parameters that dictate how
an area will respond to precipitation events. The hydrologic response (as represented by a
hydrograph) varies both temporally and spatially depending on the combination of these basic
parameters.
•
•
•
In general, a catchment with steep terrain, such as those typical of the project tenure area,
tends to yield a quick response to rainfall events, whereas a catchment with flat or
undulating terrain will exhibit a slower, more evenly distributed response. Common
construction and open cut mining activities often flatten portions of the terrain and thereby
reduce the rates of storm runoff.
Soil cover has three key characteristics that affect the rate of runoff, which are soil type,
perviousness and moisture content. A loose, coarse grained, pervious soil with a low moisture
content will promote infiltration and diminish runoff; conversely, a dense fine grained soil with
a high moisture content will inhibit infiltration and promote runoff. Typical construction and
open cut mining activities tend to compact soils and reduce perviousness, and thereby
increase the rates of storm runoff.
Vegetation also plays an important role in regulating the rate of storm runoff. Plants affect
hydrology through physiological processes (uptake of water and transpiration), as well as
providing structure and stability to surficial soils that helps prevent erosion and soil loss.
Catchments with little or no vegetation tend to experience more erosion and exhibit more
rapid storm runoff than vegetated areas. Construction activities often reduce the vegetative
cover of a portion of a catchment, thus increasing the rates of runoff and erosion.
The Project is located within the Chamberlain Creek and Skeeter Creek watersheds. Both
watersheds are characterized by deeply incised channels with steep valley sides consisting
primarily of glacial till and exposed bedrock in their upper regions. Lower in their watersheds
both creeks flow out into the relatively flat Sukunka River valley and discharge over deep alluvial
fans and through a wetland prior to entering the Sukunka River. Both creeks lose sizeable
amounts of surface runoff to the groundwater system as they cross the alluvial fans.
3.0
Environment Protection Measures
The WMP describes how water will be controlled and managed during construction, operations,
and closure of the Project. The objectives of the WMP are to manage water in a manner that
provides sufficient water to support coal processing while minimizing contact water and the
potential for storm flows to cause damage to mine structures, and thereby minimizing the
potential for mining operations to cause adverse effects to downstream water quality. Water will
be controlled in a manner that minimizes erosion in areas disturbed by construction and mine
operation activities and limits the release of sediment or chemically laden water to the receiving
environment. This includes diverting non-contaminated water around the mine area, collecting
4
PRELIMINARY MINE SITE WATER MANAGEMENT PLAN
Environment Protection Measures
June 28, 2015
surface water runoff from the mine area, constructing sediment control ponds, and managing
water systems. The key facilities identified in the WMP are the:
•
•
•
•
3.1
Up to six open pits
Waste rock stockpiles
Collection ditches and diversion ditches
Sediment control ponds
WATER MANAGEMENT OBJECTIVES
This section of the WMP describes the water management objectives and provides guidance for
the control of all water originating from, or brought into, the mine site during the life of mine. The
design criteria for the various sediment control elements required will be primarily based on the
document titled “Guidance for Assessing the Design, Size and Operation of Sediment Ponds
used in Mining”, as issued by the BC Ministry of Environment, Land and Parks (BC MOE-LP 2001).
Water will be controlled in a manner that will minimize erosion in areas disturbed by construction
and operation activities. The water management strategy is to minimize disturbance areas and
implement BMPs as work progresses. The sources of water during construction and operation are
as follows:
•
•
•
•
•
3.2
Runoff from the Mine Site facilities
Runoff from the un-diverted and un-disturbed catchment around PDA
Fresh water from the Sukunka River
Groundwater from the Open Pits
Treated septic and grey water, in small quantities, from the mine wash house and other
facilities
BEST MANAGEMENT PRACTICES
Experience and adaptive management are integral to the successful selection of the
appropriate BMPs and the design and implementation of an overall WMP. Erosion control BMPs
will be implemented prior to and during construction and will be maintained as needed through
operations as needed to minimize erosion and sediment discharge into surrounding areas.
Typical BMPs that could be implemented to meet the objectives of the WMP are:
•
•
•
•
•
•
•
•
Runoff collection ditches
Runoff diversion ditches
Energy dissipaters
Slope drains
Water bars
Diversion structures
Sediment basins and sediment control ponds
Flocculant addition
5
PRELIMINARY MINE SITE WATER MANAGEMENT PLAN
Environment Protection Measures
June 28, 2015
The above is not an exhaustive list of all possible BMPs. The final suite of BMPs to be implemented
will be determined prior to construction and based on the need and appropriateness. Glencore
will provide justification for why specific BMPs are selected.
3.2.1
Collection Ditches
A runoff collection ditch intercepts contact water runoff and diverts it to a stabilized area where
it can be effectively managed. Collection ditches are used within areas to collect runoff and
convey it to appropriate sediment control measures. General locations and conditions may
include:
•
•
•
Below disturbed slopes to divert sediment-laden water to control facilities
At or near the perimeter of construction or operations activities to prevent sediment-laden
runoff from leaving the site
Above disturbed areas to prevent erosion before stabilization is achieved
Collection ditches may be either temporary or permanent structures. Collection ditches will be
inspected and maintained regularly to remove any blockages to flow (accumulated sediment,
debris, etc.) that may occur.
Flocculants will be added to contact water within the collection ditches at times when the
sediment pond capacity and BMPs are predicted to be insufficient to manage TSS levels in the
sediment pond effluent (15 mg/L TSS) as discussed in Section 4.2.1.
3.2.2
Diversion Ditches
A diversion ditch is similar to a collection ditch but is designed for clean water diversion. A
diversion ditch is a channel lined with vegetation, rip-rap, or other material designed for the
conveyance of clean surface runoff to a receiving system, without causing erosion.
3.2.3
Energy Dissipaters
Energy dissipaters are typically rip-rap lined plunge pools used to dissipate the energy of fast
flowing water and prevent erosion of natural stream channels downstream. These structures are
used in conjunction with diversion and collection ditches, and are typically located upstream of
a receiving waterbody (e.g., stream, pond, lake, etc.), or within long diversion ditches to prevent
erosion of the ditch itself. Energy dissipaters will be inspected and maintained regularly to
remove any blockages to flow (e.g., accumulated sediment, debris, etc.) that may occur.
3.2.4
Slope Drains
Slope drains consist of flexible tubing, a perforated pipe bedded in gravel, or a similar conduit
and are required to convey concentrated runoff into the appropriate BMP structure when
ditches are deemed impractical. Slope drains shall be sized according to estimates of peak
flows, which are dependent on contributing drainage area. Slope drains will be inspected and
6
PRELIMINARY MINE SITE WATER MANAGEMENT PLAN
Environment Protection Measures
June 28, 2015
maintained regularly and any blocked or damaged parts will be cleaned, repaired, or removed
and replaced.
3.2.5
Waterbars
Waterbars serve to reduce sheet flow and surface erosion of areas of exposed soil and/or roads
by diverting runoff towards a stable vegetated area or collection ditch. Spacing of waterbars
will be field fitted based on the slope grade and general susceptibility of the surface to erosion.
Waterbars must not direct runoff into a ditch that will channel water toward the watercourse
unless the ditch is adequately prepared with check dams and armouring, where appropriate.
Waterbars will require regular monitoring when subjected to frequent traffic crossings.
3.2.6
Temporary Diversion Structures
A temporary diversion structure typically consists of sandbags stacked in a pyramid formation
with a polyethylene sheet placed diagonally in between the bags. Temporary diversion
structures are useful for diverting concentrated overland flow to an appropriate sediment basin
or other BMP structure where it can be effectively managed.
3.2.7
Sediment Basins and Sediment Control Ponds
A sediment basin is a temporary structure that is used to detain runoff from small drainage areas
so that sediment can settle out. A sediment control pond (SCP) is an engineered structure
designed for the life of mine that is similarly used to detain runoff from larger drainage areas to
settle sediment. Sediment basins and SCPs are generally located in areas where access can be
maintained for sediment removal and proper disposal. Sediment basins and SCPs are typically
constructed at the end of collection ditches to detain sediment-laden runoff long enough to
allow the majority of the sediment to settle out. A sediment basin can be created by excavating
a basin, utilizing an existing depression, or constructing a dam across a channel or depression
downslope from the work area. Sediment-laden runoff from the disturbed site is conveyed to the
basin via ditches, slope drains, or diversion structures. The basin is a temporary measure, with a
nominal design life of approximately six months, and is to be maintained until the site is
permanently protected against erosion by vegetation and/or structures. The size of the
temporary sediment basin is dependent on the size of the drainage area and the estimated rate
of runoff. The exact location and final geometry of each basin should be field-fitted to integrate
with the terrain to minimize disturbance. SCP design and placement is discussed in detailed in
Section 3.3.2.3.
3.2.8
Flocculent Addition
To assure sediment pond discharge suspended solids are within regulatory requirements,
“potable” flocculants may be added to assist solids settlement. Control systems will be in-place
to prevent overdosing flocculants in the run-off water collected.
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PRELIMINARY MINE SITE WATER MANAGEMENT PLAN
Environment Protection Measures
June 28, 2015
3.3
WATER MANAGEMENT MEASURES
3.3.1
Preliminary Mine Site Water Management Plan Overview
The project WMP is depicted visually on Figure 3.3-1. As shown, contact water will be minimized
by the construction of diversion ditches upslope of Pits 1, 2 and 3. Water diverted in these ditches
will be routed back to the main stream that it would have naturally discharged to via natural
micro-tributaries. These micro-tributaries will be enhanced using rip-rap in order to safely convey
the additional discharge.
Contact water will be collected in downslope collection ditches and will be routed through a
sediment basin or SCP prior to being discharged to the natural environment. Waste rock
stockpile contact water will naturally flow downhill into the collection ditches, whereas pit
contact water will flow via gravity in channels to the collection ditches or be collected in
engineered low points in the pit and then be pumped to the collection ditches. Water collected
in the South Collection Ditch will be routed through the south sediment collection pond (SSCP)
prior to discharging to Chamberlain Creek. Water collected within the north collection ditch
(NCD) and west collection ditch (WCD) will be routed through the north and west sediment
control ponds (NSCP and WSCP) before being discharged to the Sukunka River via water pipe.
The sediment basins and SCPs will settle out sediment the size of, or greater than, silt.
Additional details regarding each major water management structure are provided in the
following sections.
3.3.2
Description of Water Management Measures
This section describes specific water management elements that will be utilized on site, and
describes how they will be operated. The location of major surface drainage controls is shown
on Figure 3.3-1.
3.3.2.1 Dewatering
Dewatering of the excavation areas, including the open pit areas, will be accomplished by
directing water to the collection ditches by open channel flow, or by the use of sump pits, wells,
well-points and/or removable pumping stations. Runoff and seepage from construction and
operational dewatering will be collected and discharged to the environment via down gradient
collection ditches and SCPs. In addition, a portion of the contact water in Open Pit 1 may be
pumped for use in the CHPP.
3.3.2.2 Collection and Diversion Ditches
The WMP includes collection ditches to route water to areas within the Mine Site where it is
required, or to divert contact surface runoff to downstream sediment basins or SCPs. Major
collection ditches will be constructed around the downslope footprint edge of the Waste Rock
8
PRELIMINARY MINE SITE WATER MANAGEMENT PLAN
Environment Protection Measures
June 28, 2015
Piles and Open Pits, as shown on Figure 3.3-1. Collection channels will typically be lined with riprap or other engineered protection, when not cut in rock.
The WMP includes diversion ditches to route upslope water around the PDA and into existing
stream channels. Diversion ditches will be constructed upstream of the Open Pits on slopes
conducive to ditch construction and will be similarly lined with vegetation, rip-rap or engineered
protection, when not cut in rock. The location of all major diversion ditches are shown on Figure
3.3-1. The outlets of diversion channels will be fitted with energy dissipation structures and/or
armoured with rip-rap to prevent erosion at points of confluence with natural channels. Both
collection and diversion ditches will be designed in accordance with t the design criteria
detailed in Section 3.3.3.1 below.
The collection and diversion channels proposed in the WMP will be designed to minimize ditch
bypass. Bypass of a collection or diversion channel results from the ability of the structure to
capture and retain water from up-gradient areas. The following criteria and the factors
influencing them are used to evaluate expected channel performance:
•
•
•
Capture Efficiency: The percentage of the total available flow from the up-gradient
catchment that is captured by the channel. This includes surface water flow and
groundwater flow.
− The Capture Efficiency is expected to vary spatially along the proposed collection
channels.
− Capture Efficiency is estimated to be high in areas where the overburden is relatively thin
and where sub-surface conditions promote groundwater discharge to surface.
− The Capture Efficiency will be lower in areas where thicker overburden deposits allow for
groundwater to remain in the sub-surface.
Ditch Loss: The percentage of the flow in the channel that is not conveyed to the outlet, i.e.
lost through seepage out of the channel.
− Ditch loss is dependent on the hydraulic conductivity of the channel lining for lined
channels or surficial material for unlined channels
Net seepage capture efficiency: The overall efficiency considering both capture efficiency
and the ditch loss.
The capture efficiency of the proposed channels varies spatially depending on the thickness of
surficial materials along the channel alignment. Sections of the channel constructed in bedrock
cut will exhibit relatively high Capture Efficiency while those overlying thick surficial overburden
deposits or fill are expected to have lower capture efficiency due to groundwater bypassing
under the channel. The range of capture efficiency values is expected to vary locally between
approximately 65 and 95 percent.
9
!
!
588000
590000
592000
±
!
Sukunka River 6126000
110
0
!
13 00
!
13 00
14
00
!
!
!
900
6126000
586000
!
584000
13
00
!
6124000
A
!
!
12 00
!
!
k a River
!
12
00
12
00
!
A
!
Suk un
!
!
0
90
!
!
!
!
!
!
!
Ì
!
!
!
!
!
!
!
!
!
Skeeter Creek
!
!
Ì
Ì
Ì
Ì
Ì
Ì
6122000
!
6122000
!
Pit 04
!
A
1100
!
!
Pit 01
!
0
70
!
16 00
!
Sukunka River
!
!
A
!
"
6120000
!
6120000
!
Pit 05
A
A
Pit 02
1700
0
80
Pit 06
Ch
am
be
rl
ain
A
Cr
ee
6118000
6118000
k
00
13
Pit 03
13
00
00
13
Camp Options
< Camp Option 1
Camp Option 2
1700
1200
0
18 0
1300
Mt. Chamberlain (1800 m)
#
00
18
CHPP Option 1
Option 2
17 00
Haul Road Options
Option A
18
00
1800
A
13 00
CHPP
0
12 0
1600
Option B
A
Option E
0
1
2
3 km
"
584000
#
AA
16 00
1:40,000
12
00
"
586000
Mountain
Diversion Ditch
Conceptual Open Cut Pit
A
Oil & Gas Well
Collection Ditch
Conceptual Waste Stockpile
"
Oil & Gas Facility
HDPE Pipe
Explosives Reload Facility
Mine Infrastructure
Haul Road
Mine Infrastructure Area
Open Channel
Sediment Control Pond
Road
Railway
Pipeline
Contour Line
(20 metre interval)
Watercourse
Waterbody
Ì
A
588000
No.1 Mine
Chamberlain Seam
Substation
Sukunka Project Tenure Area
Figure does not include mitigations
related to waste rock stockpile placement
required for protection of water quality
590000
592000
SUKUNKA COAL MINE PROJECT
PREPARED BY:
SUKUNKA PROJECT LAYOUT
Project Development Area
ROM Stockpile
No.1 Mine
Skeeter Seam
16 00
0110
19 00
Option D
PREPARED
FOR:
WATER MANAGEMENT PLAN
Data Sources: Glencore, Province of British Columbia, Government of Canada
Disclaimer: Although there is no reason to believe that there are any errors associated with the data
used to generate this product or in the product itself, users of these data are advised that errors in
the data may be present.
File Path: fig_10482_wmp_hydrology_03_03-01_sukunka_project_layout
DATE:
25-JUN-15
FIGURE ID: 123110482
PROJECTION: UTM 10
DRAWN BY:
DATUM:
CHECKED BY: K. TERRY
NAD 83
D. COOK
FIGURE NO:
3.3-1
It should be noted that mitigations related to waste rock stockpile placement and water management identified in the water quality model report
(Appendix 27.0-A.14 Water Quality Model) are not shown on Figure 3.3-1 or discussed in this document
6114000
<
Transmission Line Options
Option 1: Sukunka
!
! FSR to the Spectra
Gas Compressor Station
Option 2: Meikle
Creek Road to
!
!
Transmission Line
at HWY 29
Option 3: Sukunka
!
! FSR to BC Hydro’s
SKN Substation
6114000
6116000
14 00
6116000
A
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00
PRELIMINARY MINE SITE WATER MANAGEMENT PLAN
Environment Protection Measures
June 28, 2015
The ditch loss for the proposed channels at the Sukunka Project is estimated to be less than
5 percent for the majority of channel conditions. The ditch loss for a given channel section is
dependent on the hydraulic conductivity of the channel. Channel sections constructed in
bedrock cut will exhibit relatively low ditch loss. Channels constructed in overburden or on fill
materials will have greater losses. Areas where the in situ materials do not meet the required
hydraulic conductivity criteria will be improved through installation of a liner, grouting or other
ground improvement techniques. Figure 3.3-2, Figure 3.3-3 and Figure 3.3-4 illustrate typical
channel sections constructed in rock cut, overburden and fill materials, respectively. The
channels sections shown on Figure 3.3-3 and Figure 3.3-4 show the potential use of a liner to
minimize ditch loss should it be necessary.
The net seepage efficiency for the Project collection ditches is therefore estimated to be
approximately 60 to 90 percent. The actual value will depend on the proportion of runoff
contributing from areas with relatively high or low capture efficiency and ground conditions
along the ditch alignment encountered during further investigation and construction. For the
purposes of the water quality assessment, an overall net seepage efficiency of 85 percent was
used (Appendix 27.0-A.14 Water Quality Model).
3.3.2.3 Sediment Control Ponds
Sediment control ponds will be constructed downstream of most construction and all operations
activities. The ponds will be designed in accordance with the Guidelines (BC MOE-LP 2001), and
to the design criteria detailed in Section 3.3.3.1 below. General considerations are that the
ponds be constructed with a long and narrow shape (5L:1W), with sufficient surface area to
facilitate settling, and with sufficient depth to provide a minimum 1.5 m of water cover above
accumulated sediment. The SCPs will be designed to settle sediment during 1 in 10 year flood
events. Furthermore, the ponds will be designed with an overflow spillway sized to safely pass 1 in
200 year flood flows. Water treated in the SCPs will either be discharged to existing channels via
energy dissipating structures (SSCP), or via water pipe to the Sukunka River (WSCP and NSCP).
The locations of the three major proposed SCPs (SSCP, WSCP and NSCP) are shown on Figure
3.3-1. All sediment ponds will require inspection and maintenance on a scheduled basis, as well
as after all substantial storm events (e.g., 24-hr rainfall exceeds 10 mm).
11
SUKUNKA COAL MINE PROJECT
NORTH COLLECTION CHANNEL
TYPICAL SECTION IN ROCK CUT
ENVIRONMENTAL ASSESSMENT - DISCIPLINE
Data Sources: Glencore, Province of British Columbia, Government of Canada
Disclaimer: Although there is no reason to believe that there are any errors associated
with the data used to generate this product or in the product
itself, users of these data are advised that errors in the data may be present.
File Path:Fig_3.3-2_rA - North Collection Channel Rock Cut
DATE:
25-JUN-15
FIGURE ID: 123110482
DRAWN BY: PP
PROJECTION: UTM 10
NAD 83
DATUM:
CHECKED BY: DF
PREPARED BY:
PREPARED
FOR:
FIGURE NO:
3.3-2
SUKUNKA COAL MINE PROJECT
NORTH COLLECTION CHANNEL
TYPICAL SECTION IN OVERBURDEN
ENVIRONMENTAL ASSESSMENT - DISCIPLINE
Data Sources: Glencore, Province of British Columbia, Government of Canada
Disclaimer: Although there is no reason to believe that there are any errors associated
with the data used to generate this product or in the product
itself, users of these data are advised that errors in the data may be present.
File Path:Fig_3.3-3_rA - North Collection Channel Overburden
DATE:
25-JUN-15
FIGURE ID: 123110482
DRAWN BY: PP
PROJECTION: UTM 10
NAD 83
DATUM:
CHECKED BY: DF
PREPARED BY:
PREPARED
FOR:
FIGURE NO:
3.3-3
SUKUNKA COAL MINE PROJECT
NORTH COLLECTION CHANNEL
TYPICAL SECTION ON FILL
ENVIRONMENTAL ASSESSMENT - DISCIPLINE
Data Sources: Glencore, Province of British Columbia, Government of Canada
Disclaimer: Although there is no reason to believe that there are any errors associated
with the data used to generate this product or in the product
itself, users of these data are advised that errors in the data may be present.
File Path:Fig_3.3-4_rA - North Collection Channel on Fill
DATE:
25-JUN-15
FIGURE ID: 123110482
DRAWN BY: PP
PROJECTION: UTM 10
NAD 83
DATUM:
CHECKED BY: DF
PREPARED BY:
PREPARED
FOR:
FIGURE NO:
3.3-4
PRELIMINARY MINE SITE WATER MANAGEMENT PLAN
Environment Protection Measures
June 28, 2015
3.3.3
Water Management Design Elements
For the purpose of the WMP, the Project has been subdivided into a number of hydrologic
catchments delineated according to natural drainage boundaries and/or the artificial
boundaries of collection and diversion ditches, as shown on Figure 3.3-1 and listed in Table 3.3-1.
Table 3.3-1
Catchment Areas of Key Water Management Features
Type
Contact
Water
NonContact
Water
Description
Catchment
Area (km2)
Area contributing to the north collection ditch and the north sediment
control pond
9.64
Area contributing to the west collection ditch and the west sediment control
pond
8.85
Area contributing to the south collection ditch and the south sediment
control pond
2.01
Area contributing to the north diversion ditch and Skeeter Creek
3.62
Area contributing to the west diversion ditch and Chamberlain Creek
1.04
Area contributing to the south diversion ditch and Chamberlain Creek
8.49
3.3.3.1 Design Criteria
A risk-based approach is used to select appropriate design storm events for each water
management feature. This approach weighs the likelihood of failure versus the consequence of
failure, on a case-specific basis. BMPs generally dictate minimum prescriptive standards;
however, feature-specific design basis criteria may be used that exceed minimum standards
should the calculated risk warrant it. Design storm events are developed by assessing the annual
recurrence interval of precipitation events of a given magnitude, as described in Section 2.1.3.
Design storm events are typically used as input parameters to a rainfall-runoff type storm water
model such as HEC-HMS, HydroCAD, and TR-55. In northern climates such as in British Columbia,
snowmelt is also considered to occur during the design storm event. The design criteria for
various design elements are listed in the Table 3.3-2 below.
15
PRELIMINARY MINE SITE WATER MANAGEMENT PLAN
Environment Protection Measures
June 28, 2015
Table 3.3-2
Design Criteria
Design Element
Design Criteria
Anticipated Exposure
Time
Diversion Ditches
Peak flow from 1 in 10 year return period flood with
a > 0.2 m freeboard
Life of Mine
Collection Ditches
Peak flow from the 1 in 200 year return period flood
with a > 0.2 m freeboard
Life of Mine
Sediment Control Ponds
(surface area)
1 in 10 year return period flood hydrograph and a
maximum settling velocity of 5 x 10-5 m/s
Life of Mine
Sediment Control Pond
Spillways
Peak flow from the 1 in 200 year return period flood
hydrograph with a > 0.5 m freeboard
Life of Mine
Dewatering Open Pits
1 in 10 year return period 24-hour storm dewatered
in 24 hours
Life of Mine
NOTES:
PMP—Probable Maximum Precipitation
PMF—Probable Maximum Flood
3.3.4
Water Management Measures by Project Phase
This section describes the timing of specific water management elements that will be used
where required throughout the site. The closure water management measures described in
Table 3.3-3 include decommissioning much of the water management infrastructure and
restoring natural drainage. These activities will only be completed once water quality is sufficient
to allow discharge from the closed project site directly to Skeeter and Chamberlain creeks
without resulting in unacceptable water quality within the receiving environment.
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PRELIMINARY MINE SITE WATER MANAGEMENT PLAN
Environment Protection Measures
June 28, 2015
Table 3.3-3
Construction Water Management Measures
Activity
Potential Requirement
Construct access
roads
Interrupt natural drainage
Potable water needs
Construct
Construction Offices
Clearing and
grubbing open pit
and waste rock
stockpiles
Septic and grey water
production
Sediment laden runoff
Water Management Measures
1.
Employ appropriate BMPs to route runoff and
mitigate erosion
2.
Potable water will be trucked to site
3.
Construction office septic and grey water will
be stored in tanks for offsite disposal in
approved municipal waste water treatment
systems
4.
5.
6.
Construct diversion ditches above work area
Construct collection ditches below work area
Construct and route collection ditches to
sediment control ponds
Construct water discharge pipe and route
water from North and West Sediment Control
Ponds to the Sukunka River
Employ appropriate BMPs
7.
8.
Develop open pits
Water requirement for
coal washing and surface
run-off management
Construct CHPP
Table 3.3-4
Dewatering
9.
Prepare and commission dewatering system
and route contact water to collection ditches
10. Construct Sukunka River water supply wells
and pipeline
11. Build diversion ditches to divert
uncontaminated run-off around the
construction site.
12. Build construction collection ditches to divert
surface run-off through a sediment control
pond that will discharge to Skeeter Creek.
After the North Collecting Ditch is constructed,
the CHPP construction sediment pond will
discharge into the North Collection Ditch.
Operations Water Management Measures
Activity
Potential Effect/Need
Water Management Measures
1.
2.
Operate open pits
and waste rock
stockpiles
Collect contact water
Divert non-contact water
Operate sediment
control ponds
Treat contact water
3.
Maintain collection ditches
Pump contact water from Pit 1 to CHPP to
meet plant demand
Pump remaining contact water from Pit 1 and
all contact water from Pits 2 to 6 to nearest
appropriate collection ditch
4.
Maintain diversion ditches
5.
Maintain sediment control ponds
17
PRELIMINARY MINE SITE WATER MANAGEMENT PLAN
Monitoring Program
June 28, 2015
Table 3.3-4
Operations Water Management Measures
Activity
Potential Effect/Need
Water Management Measures
6.
Operate CHPP
Use contact water for coal wash when
sufficient water is available. Use freshwater
from the Sukunka River supply line to cover
short fall
Collect wash water, clarify, and then
recirculate to the CHPP for re-use.
Coal Wash
7.
Operate
Accommodation
Camp
Table 3.3-5
Potable water
Septic and grey water
8.
Maintain potable water supply wells
9.
Maintain treatment system and discharge
treated water into local watershed
Closure Water Management Measures
Activity
Closure/Reclamation of
Open Pits and Waste
Rock Stockpiles =
Potential Effect/Need
Return natural drainage
Water Management Measures
1.
2.
Decommission dewatering systems and
water supply systems
Employ appropriate BMPs
NOTES:
More detailed information regarding closure is provided in the preliminary Reclamation Plan (Section
20.0-A.14)
4.0
Monitoring Program
4.1
MONITORING
Effluent discharge from mining processes is currently regulated under the Environmental
Management Act and effluent discharge permits issued by the BC MOE. Monitoring will be
completed to confirm compliance with the permits issued. Water quality sampling and flow
measuring facilities will be part of the design of the various water management measures to
meet all monitoring requirements.
Septic and grey water discharge is currently regulated by the BC MOE for discharges greater
than 22.7 m3/d and by the BC Ministry of Health for discharges less than 22.7 m3/d. Monitoring will
be completed to confirm compliance with any permits issued. Sampling and flow measuring
facilities will be part of the design of the various water management measures to meet all
monitoring requirements.
Monitoring and reporting objectives are contained in Section 5.2 Water Quality.
18
PRELIMINARY MINE SITE WATER MANAGEMENT PLAN
Monitoring Program
June 28, 2015
4.2
FOLLOW-UP AND ADAPTIVE WATER MANAGEMENT STRATEGY
If effluent is found to be, or modelled to be, repeatedly outside of the guidelines, an adaptive
management plan will be developed to ensure the effluent discharge conforms to permit
requirements. An example of adaptive management is including provisions in the design of the
SCPs for aiding settling (Section 4.2.1). If SCP effluent is not meeting guidelines for total
suspended sediment (TSS), a settling aid will be considered. Further discussion on follow-up and
adaptive water management is provided in Section 5.2 (Water Quality) of the Application.
4.2.1
Flocculants Use to Aid Settling
The sedimentation ponds are being designed to meet the 15 mg/L TSS effluent criterion
described in the Metal Mining Effluent Regulations and to settle particles 10 µm or greater during
the 1 in 10-year, 24-hour runoff condition. The sedimentation ponds will be sized to promote
gravity settling of sediment from the collection ditches within time frames appropriate to the
sediment particle size. For example, sand and coarse silt settle within hours, while fine silt and
clay will require 24 hours or longer to settle. During times of high flow, when TSS levels are high
and there is insufficient time for natural settling to allow the TSS discharge criterion to be met,
flocculants will be used to promote settling of sediment. Flocculants will be added to influent
water upstream of the sedimentation ponds to allow time for settling.
The kind and amount of flocculants to be used will be evaluated prior to operation, and a
suitable dosing regimen developed. Considerations for selection and use of flocculants are
(Clark and Jayasena 2013):
•
•
Potential for toxicity to aquatic life in released effluent (resolved by selecting low-toxicity
flocculants, typically a neutral, anionic or mixed neutral-cationic-anionic type, as higher
toxicity is associated with cationic type flocculants; Clark 2010)
Potential for reduced settling capacity, if the flocculants use is too high (a protective colloid
effect, frequently irreversible, that results in decreased settling efficiency and increased TSS
as more flocculants are added)
The following information will be collected to guide use of flocculants (outlined in MELP 2001)
•
•
•
Review of available flocculants and selection of an effective, low toxicity flocculant
Soil particle size analysis and settling tests on upslope soil samples to identify relevant size
fractions of sediment and any needs for flocculants
Sizing of the sedimentation pond to capture the plus 10 µm particle size when runoff flow into
the pond is for the 10-year, 24-hour rainfall event
The amount of flocculants required will take into account flow rate into the pond, TSS in water
entering the pond, particle surface area, adequate mixing subsequent to adding the
flocculants to the runoff (i.e., location of flocculants addition), and time needed for mixing in the
flocculants.
19
PRELIMINARY MINE SITE WATER MANAGEMENT PLAN
References
June 28, 2015
When flocculants are used to settle sediment, toxicity of the sediment pond water will be tested
using the Ceriodaphnia dubia bioassay (48 hour LC50) and rainbow trout bioassay (96 hour
LC50). Because the flocculants bind to the sediment particles and settle in the ponds, minimal
concentrations (and toxicity) of flocculants in pond discharge water are anticipated. The
Environmental Management Act effluent permit will set the conditions for toxicity testing;
however, it is anticipated that a sample will be collected for testing within 24 hours of starting
flocculants use, and weekly thereafter.
5.0
References
British Columbia Ministry Environment, Land and of Parks (MELP). 2001. Draft – Guidance for
Assessing the Design, Size and Operation of Sedimentation Ponds used in Mining.
Available online at: http://www2.gov.bc.ca/gov/DownloadAsset?assetId=8F1FAE8C9A
D94A2CBFC5C570A41A2D0F.
British Columbia Ministry of Environment. 2013. The Effluent Permitting Process under the
Environmental Management Act – An Overview for Mine Project Applicants. Available
online at: http://www.env.gov.bc.ca/epd/industrial/mining/pdf/effluent_permitting_
guidance_doc_mining_proponents_apr2013.pdf.
Clark, J.P. 2010. Treatment of Mine Site Runoff Containing Suspended Solids Using Sedimentation
Ponds – Optimizing Flocculant Addition to Ensure Discharge Compliance. In:
Wolkersdorfer, C. and A. Freund (Editors), Mine Water and Innovative Thinking
Proceedings of the 2010 International Mine Water Association. Sydney, NS. pp. 217-220
Clark, J.P. and H. Jayasena. 2013. Using the BC Guidance for Assessing the Design, Size and
Operation of Sedimentation Ponds used in Mining to Comply with Federal/Provincial
Sediment Control Legislation. Available at: http://www.academia.edu/6165975/
Clark_J_C_et_al_BC_Mine_2013.
Demarchi, D. 2011. The British Columbia Ecoregion Classification – Third Edition. Ministry of
Environment. Victoria, BC. Available online at: http://www.env.gov.bc.ca/
ecology/ecoregions.
Herschfield, D.M., 1961. Rainfall Frequency Atlas of the United States for Durations from 30
Minutes to 24 Hours and Return Periods from I to 100 Years. U.S. Department of
Commerce, Technical Paper No. 40.
Herschfield, D.M., 1965. Method for estimating probable maximum precipitation, J. American
Waterworks Association, Vol. S7, p. 965-972.
Knight Piesold Ltd. 2014a. Watershed Model Report. Ref. No. VA101-511/1-2, Rev. 0, In Progress.
Knight Piesold Ltd. 2014b. Baseline Hydrology Report. Ref. No. VA101-511/1-1, Rev. 0, January 30
2014.
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