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APPENDIX B
SOUTH EMBANKMENT DAM-TYPE SELECTION STUDY
(Pages B-1 to B-34)
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SOUTH DAM TMF15 OCTOBER 2010
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T es of Water Retainin Dams
Water Retaining Dams for TMF Site ACRD Concept Familiarization ams va uate or Sout am
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TYPES OF WATER RETAINING DAMS
Concrete Faced Rockfill Dam (CFRD)
Zoned Earthfill/Rockfill Dam
Geomembrane Faced Rockfill Dam (GFRD)
Asphaltic Core Rockfill Dam (ACRD)
Roller Compacted Concrete Dam (RCC)
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CONCRETE FACED ROCKFILL DAM
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CFRD PROS AND CONSPros
Rockfill zone is unsaturated and slopes can be constructedsteeper that earth fill dams(1:3H to 1:5H:1V versus 2H to
.
Plinth and grouting can take place independently of the other
dam construction
Design for leakage through opened joints and tension cracks.
Large compression cracks can occur in high CFRD`s in narrow
va eys Cannot provide storage during construction
Not a common construction practice in BC and Canada
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EARTHFILL DAM PROS AND CONSPros
resistance Earth core design most economic if suitable borrow areas are
Earthfill dam have been used for many years and the efficiency
of this type of dam is well documentted
Cons
Difficult to construct in rainy weather
Largest quantity or fill required Foundation treatment in the core zone to avoid erosion of the
core material along the fractured rock surface
More vulnerable to overtopping during construction
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GEOMEMBRANE FACED ROCKFILL DAM
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GFRD PROS AND CONSPros
constructed steeper that earthfill dams(1:3H to 1:5H:1V versus2H to 2.5H:1V)
dam construction
Membrane flexibility to accommodate rockfill deformations
Vulnerable to impacts, ice loads, sabotage, effects ofweathering and aging.
equ res part a or u y covere protect ve ayer t atincreases cost
Cannot provide storage during construction
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ASPHALTIC CORE ROCKFILL DAM
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ACRD PROS AND CONS
Pros
-,
ability to self heal. Core is protected from reservoir debris, impact loads from ice
.
Allows reservoir storage during construction and simplified
coffer dam and water diversion designs
Requires specialized asphalt paver, and asphalt plant
Specialized contractor training
Cost
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A T T A
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RCC PROS AND CONSPros
Smallest dam volume
Cons
Very expensive
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DAM RELATIVE COSTS
Earthfill core dam the most economic.
ACRD and GFRD fits in between. .
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FACTORS THAT DETERMINE WHICH
Construction costs
Weather conditions
Total construction time
ons ruc on exper se
Potential dam overtopping during
constructionMaintenance costs
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Can be built with lower grade rockfill.
Core can be built in rainy cold weather.
the rest of the embankment zones.
permeability material of substantial
is not available close to site
e uc on n cons ruc on sc e u e
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ACRD HISTORY
Technology developed in the 1960s in
Germany.Dams built in Austria, German , Norwa ,
China, Iran, South Africa, Spain, Saudi
ArabiaDam construction underway in Canada
More than 100 dams have been built or.
Highest is 170 m
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EMBANKMENT ZONES
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CORE PAVER SCHEMATIC
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SIMULTANEOUS COMPACTION OF AC
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PLACING ASPHALT MASTIC ON CONCRETE
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CROSSING THE AC ZONE
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SOUTH DAM ALTERNATIVE DESIGN STUDY Relative merits of five embankment design
.
CFRD, Earthfill dams and RCC were not practicalalternatives for the South dam site
ACRD and GFRD options were evaluated to determine
the preferred dam designcontacte o o e e e, orway s ma or asp a tcontractor and a subsidiary of Veidekke a leader inas halt core dam construction to assist with the
ACRD evaluation KP provided a preliminary design concept to Helge
axegaar wor ng on en ers n ue ec w o
provided a design review, cost estimate andconstruction schedule
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KITSAULT SITE CONDITIONS Considerable snow and sub-zero temperatures in
Asphalt and geomembrane work would be suspended inthese two months.
Thin weak overburden layer overlying bedrock,
remove and found dam on rock.verage am e g t o meters un er t e crest
Dam starter crest is 805 meters
freshet
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A I A T
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A A I A T
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GFRD vs ACRD CROSS SECTION
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MAJOR QUANTITY SUMMARY
ITEM AFRD GFRD
Foundation Preparation (m3) 150,000 200,000
Grouting (m) 2,900 4,500
Grout Trench/Concrete 2,800 1,200
Zone F/T (M m3) 0.5 0.8
Zone C Roc i M mPatsy DumpOpen Pit
3.52.1
3.54.0
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COST SUMMARY MILLIONSITEM AFRD GFRD
oun a on re ara on . .
Grouting 1.2 1.8Grout Trench/Concrete Plinth 2.8 1.2
Water Retention Zone 17.3 11.0
Zone F/T 5.0 15.7
Zone C RockfillPatsy DumpOpen Pit
14.921.9
14.940.0
Subtotal 64.6 86.6
Engineering, Permitting (7%)Construction Management (4%)Contingency(30%)
4.52.619.4
6.13.5
26.0
Total 91.1 122.2
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SUMMARY AND CONCLUSIONS50 years of successful experience with the
No case of reported leakage through theasphalt coreComparative stu y was comp ete or a GFRD
and ACRD at the South Dam site.
design alternativeACRD construction schedule is 70 to 90 days
or er an or con ruc on.
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APPENDIX C
TMF SEEPAGE ASSESSMENT AND EMBANKMENT STABILITY ANALYSES
Appendix C1 TMF Seepage Assessment
Appendix C2 TMF Embankment Stability Analyses
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APPENDIX C1
TMF SEEPAGE ASSESSMENT
(Pages C1-1 to C1-11)
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APPENDIX C1
AVANTI KITSAULT MINE LTD
KITSAULT PROJECT
TMF SEEPAGE ANALYSIS
1.1 GENERAL
Steady state seepage analyses for the Tailings Management Facility (TMF) were carried out to estimatethe amount of seepage through the embankments and foundation materials. The analyses were
conducted using the finite element computer program SEEP/W (GEO-SLOPE International, Ltd.).
Seepage rates were estimated for various embankment stages throughout the life of the mine.
The South starter embankment will be constructed using rockfill material with a central asphalt concrete
core. Rockfill placed downstream and a compacted cyclone sand core will be used during subsequent
raises of the dam. The Northeast starter embankment will be constructed using rockfill with a liner on the
upstream face. Compacted cyclone sand will be used during subsequent raises of the dam.
The seepage rate through foundation materials and embankment fill zones is influenced by the following
factors:
Permeability of the embankment zones
Permeability of the foundation materials
The thickness and permeability of the tailings stored within the TMF
Seepage gradients in the embankment and foundation zones, and
The seepage area available (increases with time during operations)
The seepage flow rate is expected to vary over the life of the TMF, as it is gradually filled with tailings.
During operation of the TMF, the tailings deposit will increase in thickness and decrease in permeability
due to on-going consolidation.
Seepage analyses have been performed to predict seepage flows from the TMF for the following cases:
Just prior to mill start-up, when the start-up pond is at El. 750 m and no tailings have been depositedwithin the TMF (embankment crest elevation = 805 m)
Year 2 when the embankments are still water retaining and a suitable tailings beach has beendeveloped (embankment crest elevation = 805 m)
At the end of year 14 (end of mine operations), when the pond elevation is 856 m and the crest is at
861 m.
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Knight PisoldC O N S U L T I N G
Embankment. The seepage flow was calculated based on the seepage flux through the tailings
embankments, and multiplied by the average crest length of the corresponding stage.
1.2 SUMMARY OF MATERIAL PERMEABILITIES
The saturated permeability values have largely been chosen in order to simplify calculations and provide
a conservative estimate of the seepage. The permeability of the tailings embankment, tailings deposit and
foundation materials are described below:
To account for sub horizontal laminations (layers) formed from material segregation during
deposition, the horizontal permeability of the tailings was considered to be one order of magnitudegreater than the vertical permeability. Accordingly, the tailings deposit was assigned an anisotropic
permeability of kv= 1.0 x 10-7
m/s and kh= 1.0 x 10-6
m/s, based on typical values from previous
studies.
Compacted cyclone sand was assigned a permeability of 5.0 x 10-6
m/s, based on similar experience
with sand dam construction. The material was assumed to be isotropic.
A zone of fractured bedrock was modelled and assigned an average permeability of 1.0 x 10-6
m/s,
based on the in-situ packer permeability testing data. The data indicate slightly higher bedrock
permeability towards the surface. The material was assumed to be isotropic.
The bedrock beneath the fractured zone was assigned an average permeability of 1.0 x 10-7
m/s,
based on the in-situ packer permeability testing data. The material was assumed to be isotropic.
Waste rock shell zones of the embankments were assigned a permeability of 1 x 10-4
m/s. The
results of the model revealed that these zones are essentially fully drained and do not affect the
results of the analysis.
The asphalt core for the South starter embankment and the upstream liner for the Northeast starter
embankment were assumed to be impermeable material, in order to simplify the analysis.
1.3 BOUNDARY CONDITIONS
Boundary conditions used in the seepage analyses were selected to represent the hydrogeological
conditions expected during operation of the TMF. The boundary conditions used in the analyses are
summarised as follows:
A total head boundary was used to represent the upstream head pond elevation. The water retained
at mill start-up was estimated to be at an elevation of 750 m, based on 10 Mm3
of water impounded.As tailings are deposited from the embankments, it is anticipated that a gentle sloping beach will form
several hundred metres wide from the embankment crest down to the pond elevation. Accordingly, a
200 m beach was assumed in the seepage analyses.
A total head boundary was used to represent the phreatic surface at the downstream toe of the
K i ht Pi ld
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Knight PisoldC O N S U L T I N G
1.4 SUMMARY OF RESULTS
The SEEP/W Finite Element model is shown on Figures C1.1 to C1.5 for the South and Northeast
embankments. The results of the seepage analyses are summarized in Table C1.1.
1.4.1 South Embankment
Prior to tailings deposition, the embankment will retain water to an elevation of 750 m. The expected
seepage at mill start-up was estimated to be 14 l/s. Once mine operations begin, the fracture zones are
expected to be blinded off by the low permeability tailings within approximately 6 months. From Years 1to 14, the seepage is largely controlled by tailings permeability and pond level. The expected seepage
for the embankment at the end of Years 2 and 14 when at capacity was estimated to be 7 l/s and 19 l/s,
respectively. After Year 14 (post closure), the steady-state seepage rate is expected to remain
approximately constant. The evolution of seepage rate for the South Embankment throughout the mine
life are summarized on Figure C1.6.
1.4.2 Northeast Embankment
The tailings embankment is expected to retain a relatively small volume of water, as the initial operating
pond (El. 750 m) is expected to be lower than the Northeast embankment foundation elevation. The
seepage is not expected to exceed 3 l/s upon mine start-up. The tailings pond is expected to reach the
Northeast embankment approximately 18 months after mill start-up, at which point the seepage is
expected to be controlled by tailings permeability and pond level throughout the remainder of the mine
life. The expected seepage for the embankment at the end of Years 2 and 14 when at capacity was
estimated to be 1 l/s and 14 l/s, respectively. After Year 14 (post closure), the steady-state seepage rate
is expected to remain approximately constant. The evolution of seepage rate for the Northeast
Embankment throughout the mine life are summarized on Figure C1.7.
It is anticipated that the majority of the seepage through both embankments will be recovered by seepage
collection ponds located at the downstream toes. The flows calculated from seepage analyses do not
include for water from cyclone sand operations.
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Bedrock
Ground El. 670
Fractured Bedrock
Waste Rock1.5Pond El. 750
Crest El. 805
1
Elevation(m)
600
650
700
750
800
850
900
TAILINGS MANAGEMENT FACILITY
SEEPAGE ANALYSIS
SOUTH EMBANKMENT - YEAR 0
FIGURE C1.1
AVANTI KITSAULT MINE LTD
KITSAULT PROJECT
REV
0
P/A NO.
VA101-343/6
REF NO.
2
0 05OCT'10 GL DAYISSUED WITH REPORT KJB
DATE DESCRIPTION PREP'D CHK'D APP'DREV
680
700
720
740
Distance (m) (x 1000)
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3500
550
C1-5 of 11
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690
7 3 0
770
Bedrock
Ground El. 670
Tailings
Fractured Bedrock
Waste Rock
1.5
Pond El. 800 Crest El. 805
1
Elevation(m)
550
600
650
700
750
800
850
900
TAILINGS MANAGEMENT FACILITY
SEEPAGE ANALYSIS
SOUTH EMBANKMENT - YEAR 2
FIGURE C1.2
AVANTI KITSAULT MINE LTD
KITSAULT PROJECT
REV
0
P/A NO.
VA101-343/6
REF NO.
2
0 05OCT'10 GL DAYISSUED WITH REPORT KJB
DATE DESCRIPTION PREP'D CH'D APP'DREV
Distance (m) (x 1000)
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3500
C1-6 of 11
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69
0
7
30 7
7 0
81
0
850
Bedrock
Ground El. 670
Tailings
Fractured Bedrock
Waste Rock
Cyclone Sand
1.5
Pond El. 856 Crest El. 861
1
Elevation(m)
600
650
700
750
800
850
900
TAILINGS MANAGEMENT FACILITY
SEEPAGE ANALYSIS
SOUTH EMBANKMENT - ULTIIMATE
FIGURE C1.3
AVANTI KITSAULT MINE LTD
KITSAULT PROJECT
REV
0
P/A NO.
VA101-343/6
REF NO.
2
0 05OCT'10 GL DAYISSUED WITH REPORT KJB
DATE DESCRIPTION PREP'D CHK'D APP'DREV
Distance (m) (x 1000)
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3500
C1-7 of 11
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Bedrock
Grou nd El. 792
Tailings
Fractured Bedrock
LinerPond El. 800 Cres t El. 805
Waste Rock
Elevation(m)
725
750
775
800
825
TAILINGS MANAGEMENT FACILITY
SEEPAGE ANALYSIS
NORTHEAST EMBANKMENT - YEAR 2
FIGURE C1.4
AVANTI KITSAULT MINE LTD
KITSAULT PROJECT
REV
0
P/A NO.
VA101-343/6
REF NO.
2
0 05OCT'10 GL DAYISSUED WITH REPORT KJB
DATE DESCRIPTION PREP'D CHK'D APP'DREV
Distance (m)
0 100 200 300 400650
675
C1-8 of 11
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7
80
8
00
8
2
0
8
40
Bedrock
Ground El. 770
Tailings
Fractured Bedrock
Drains
Cyclone SandLiner
3
Pond El. 856 Crest El. 861
Waste Rock
1
Elevation(m)
700
725
750
775
800
825
850
875
900
TAILINGS MANAGEMENT FACILITY
SEEPAGE ANALYSIS
NORTHEAST EMBANKMENT - ULTIMATE
FIGURE C1.5
AVANTI KITSAULT MINE LTD
KITSAULT PROJECT
REV
0
P/A NO.
VA101-343/6
REF NO.
2
0 05OCT'10 GL DAYISSUED WITH REPORT KJB
DATE DESCRIPTION PREP'D CHK'D APP'DREV
Distance (m)
0 100 200 300 400 500 600 700650
675
C1-9 of 11
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35
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100
200
300
400
500
10
15
20
25
30
See
page(gpm)
Seepage
(l/s)
Water impoundmentfor mill start-up
Initial seepage throughfractured rock foundation
Seepage reduction due totailings deposition blinding offfractures in foundation bedrock
Steady-state postclosure seepage
00
5
-1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Year of Operation
0 05OCT'10 ISSUED WITH REPORT GL BB KJB
DATE DESCRIPTION PREP'D CHK'D APP'DREV
Mill
Startup
Seepage rate controlled by tailingspermeability and head pond level
TAILINGS MANAGEMENT FACILITYTOTAL SEEPAGE DURING MINE OPERATIONS
SOUTH EMBANKMENT
FIGURE C1.6
AVANTI KITSAULT MINE LTD
KITSAULT PROJECT
REV
0
P/A NO.
VA101-343/6
REF NO.
2
C1-10 of 11
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100
200
300
400
500
10
15
20
25
30
Seepage(gpm)
Seepage
(l/s)
Steady-state postclosure seepageInitial seepage through
fractured rock foundation
Seepage reduction due totailings deposition blinding offfractures in foundation bedrock
00
5
-1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Year of Operation
0 05OCT'10 ISSUED W ITH REPORT GL BB KJB
DATE DESCRIPTION PREP'D CHK'D APP'DREV
Mill
Startup
Seepage rate controlled by tailingspermeability and head pond level
TAILINGS MANAGEMENT FACILITYTOTAL SEEPAGE DURING MINE OPERATIONS
NORTHEAST EMBANKMENT
FIGURE C1.7
AVANTI KITSAULT MINE LTD
KITSAULT PROJECT
REV
0
P/A NO.
VA101-343/6
REF NO.
2
C1-11 of 11
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APPENDIX C2
TMF EMBANKMENT STABILITY ANALYSES
(Pages C2-1 to C2-11)
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APPENDIX C2
AVANTI KITSAULT MINE LTD
KITSAULT PROJECT
TMF STABILITY ANALYSIS
1.1 GENERAL
Stability analyses of the South and Northeast embankments were carried out to investigate the slope
stability under both static and seismic loading conditions. These comprised checking the stability of the
embankment arrangement for each of the following cases:
Static conditions
Earthquake loading from the Operating Basis Earthquake (OBE) and the Maximum Design
Earthquake (MDE), and
Post-earthquake conditions using residual (post-liquefaction) tailings strengths.
The analyses were carried out for the following embankment configurations: South Embankment with a crest elevation of 805 m (At Start-up)
South Embankment with a crest elevation of 805 m (Year 2)
South Embankment with a crest elevation of 861 m (Ultimate)
Northeast Embankment with a crest elevation of 861 m (Ultimate)
The stability analyses were carried out using the limit equilibrium computer program SLOPE/W. In this
program a systematic search is performed to obtain the minimum factor of safety from a number of
potential slip surfaces. Factors of safety have been computed using the Morgenstern-Price method.
In accordance with the Canadian Dam Association (CDA) Dam Safety Guidelines (2007), the minimum
acceptable factor of safety for the tailings embankment under static steady-state conditions is 1.5. A
factor of safety of less than 1.0 is acceptable under earthquake loading conditions provided that
calculated embankment deformations resulting from seismic loading are not significant and that the post
earthquake stability of the embankment maintains a factor of safety greater than 1.2, implying there is no
flow slide potential. The TMF would be expected to function in a normal manner after the OBE. Limited
deformation of the tailings embankment is acceptable under seismic loading from the MDE, provided that
the overall stability and integrity of the TMF is maintained and that there is no release of stored tailings or
water (ICOLD, 1995). Some remediation of the embankment may be required following the MDE.
The seismic stability assessment of the TMF has included estimation of seismically induced deformations
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1.2 MATERIAL PARAMETERS AND ASSUMPTIONS
The following parameters and assumptions were incorporated into the stability analyses:
Bulk unit weights for the embankment and foundation materials were based on typical values for
similar materials.
The embankments were assumed to be founded upon average quality rock.
An undrained shear strength was adopted to represent the tailings material strength for the static,
seismic and post-earthquake cases, as described by the following relation:
Su/p = 0.25 (static and seismic loading)
Su/p = 0.05 (post liquefaction residual strength)
where Su= undrained shear strength and p = effective vertical stress
Effective strength parameters for the zoned embankment fill materials were estimated based on
typical values for similar materials.
The shear strength of the rockfill in the embankment is assumed to have zero cohesion and a friction
angle that varies linearly with the log of the normal pressure. The shear strength relation for this type
of material is developed from recommendations by Leps (1970) for average density rockfill, and is
included graphically with Table C2.1. The phreatic surface used in the stability analysis was imported from seepage modelling (see
Appendix C1) of the South and Northeast embankments.
South embankment slopes are constructed at 1.5H:1V.
Northeast starter embankment slopes are constructed at 2H:1V.
Northeast ultimate embankment slopes are constructed at 3H:1V.
The material strength parameters adopted for the stability analyses are summarized in Table C2.1.
1.3 RESULTS OF STABILITY ANALYSES
The potential slip surfaces and calculated factors of safety for the static and post liquefaction loading
conditions are summarized in Table C2.2 and shown on Figures C2.1 to C2.3 for the South embankment
and on Figure C2.4 for the Northeast embankment.
1.3.1 Static Stability Analyses
The calculated factors of safety for each of the dam sections considered in this study exceed the
minimum factor of safety requirement of 1.5 for static normal operating (steady-state) conditions.
Deep seated and shallow slip surfaces were analysed on the upstream side of the starter embankment
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1.3.2 Seismic Stability and Deformation Analyses
The seismic stability assessment of the TMF has included estimation of earthquake induced deformation
of the embankment from the OBE and MDE events. The OBE has been defined as the 1 in 475 year
earthquake with a maximum acceleration of 0.08 g and design earthquake magnitude of 7.0. The MDE
has been conservatively taken as the 1 in 10,000 year earthquake with a peak ground acceleration
(estimated mean average value) of 0.36 g and a design earthquake magnitude of 7.5.
Embankment stability during earthquake loading has been assessed by performing a pseudo-static
analysis, whereby a horizontal force (seismic coefficient) is applied to the embankment to simulate
earthquake loading to determine the critical (yield) acceleration required to reduce the factor of safety to
1.0. The yield acceleration was determined by iterative stability analyses and varies depending on the
embankment configuration. The estimated yield accelerations for the deep seated and shallow slip
surfaces on the South embankment at mill start-up were 0.16 g and 0.3 g, respectively. The estimated
yield acceleration for the South starter embankment (El. 805 m) with 2 years of tailings is 0.25 g and for
the South ultimate embankment (El. 861 m), the estimated yield acceleration is 0.22 g. The estimated
yield acceleration for the Northeast ultimate embankment (El. 861 m) is 0.29 g. Deformation of theembankment is predicted to occur if the yield acceleration is lower than the predicted average maximum
ground acceleration along the potential slip surface from the design earthquake.
Potential slide displacements under earthquake loading from the OBE and MDE have been estimated
using the simplified methods of Newmark (1965) and Makdisi-Seed (1977). These two methods estimate
displacement of the potential sliding mass based on the average maximum ground acceleration along the
slip surface and the yield acceleration. Maximum embankment deformation calculated using the
Newmark approach does not exceed 0.4 m for the South Embankment and 0.1 m for the NortheastEmbankment, under the MDE. Average embankment deformation calculated using the Makdisi-Seed
approach does not exceed 0.5 m for the South Embankment and 0.1 m for the Northeast Embankment,
under the MDE. Maximum embankment deformation was also calculated using the Makdisi-Seed method
and does not exceed 0.8 m for the South Embankment and 0.2 m for the Northeast Embankment, under
the MDE. The displacements calculated using these methods do not impact embankment freeboard or
result in any loss of embankment integrity. Predicted embankment deformations from the OBE are
negligible (if any, as the calculated yield acceleration exceeds the estimated average maximum
acceleration) and would not impact on-going operations at the TMF.
The more recently published method of Bray (2007) was also used to predict seismically induced slide
displacement of the embankment. In addition to the yield acceleration, this method considers the
predominant period of response of the embankment under seismic loading and the corresponding
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expected foundation conditions (no overburden). Predicted embankment deformations from the OBE are
negligible, if any. For the MDE, the predicted displacements for the South and Northeast embankments
are minor and do not exceed 0.1 m.
Some deformation of the embankment is expected to result from settlement of the fill materials during
earthquake shaking. Potential settlement of the embankment crest has been estimated using the
empirical relationship provided by Swaisgood (2003). This relationship was developed from an extensive
review of case histories of embankment dam behaviour due to earthquake loading. Required inputs to
the relationship are the earthquake magnitude, the maximum acceleration on rock at the site, the depth to
rock (overburden thickness) and the embankment height. The embankment heights of the South starter,South ultimate and Northeast ultimate embankments were 135 m, 191 m and 91 m, respectively. The
resulting predicted crest settlements for the OBE do not exceed 0.1 m. For the MDE, the predicted
displacements did not exceed 0.5 m for the South embankment and 0.2 m for the Northeast
Embankment.
Post earthquake conditions, assuming complete liquefaction of the tailings deposit and using residual
(post liquefaction) tailings strengths, were analysed for the South and Northeast embankments. Table
C2.2 shows the results of the post liquefaction stability analyses. The calculated minimum factors ofsafety for each embankment section are the same as the static factor of safety because the critical
potential slip surface does not pass through the liquefied tailings deposit. The factors of safety exceed
the minimum requirement of 1.2 for acceptable post-liquefaction conditions. These results indicate that
the embankments are not dependent on tailings strength to maintain stability, and are not susceptible to a
flow slide or large deformations resulting from earthquake-induced liquefaction of the tailings deposit.
The findings of the seismic stability analyses indicate that the TMF would function normally after the OBE
and MDE. The ongoing increase in tailings strength and reduction in pore water pressures as the tailingsconsolidate will only improve the overall stability and integrity of the embankment after closure.
1.4 REFERENCES
Bray, J.D. and Travasarou, T., 2007, Simplified Procedure for Estimating Earthquake-Induced Deviatoric
Slope Displacements, Journal of Geotechnical and Geoenvironmental Engineering, Vol. 133, No. 4, April
2007, pp. 381-392.
Canadian Dam Association (CDA) 2007, Dam Safety Guidelines, Edmonton, Alberta.
Earthquake Spectra, 2008, Special Issue on the Next Generation Attenuation Project, Vol. 24, No. 1.
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Makdisi, F.I., and Seed, B.H., 1977, A Simplified Procedure for Estimating Earthquake-Induced
Deformations in Dams and Embankments, Earthquake Engineering Research Center Report No.
UCB/EERC-77/19, University of California, Berkeley, California.
Newmark, N.M., 1965, Effects of Earthquakes on Dams and Embankments, Vol. 15, No. 2, pp. 139 -159.
Swaisgood, J.R., 2003, Embankment Dam Deformations Caused by Earthquakes, Proceedings from
Pacific Conference on Earthquake Engineering, Christchurch, New Zealand, Paper No. 14.
TABLE C2.1
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Cycloned Sand (roller compacted) 18 35 0 Los Pelambres Copper Mine, Chile
Waste Rock (traffic compacted) 20 Average Leps 0 See note 1
Tailings Deposit 18 - 0 See note 2Fractured Bedrock 20 33 3.5 See note 3
Bedrock (inpenetrable) - - - Assumed
M:\1\01\00343\06\A\Report\2-Tailings Storage Facility Report\Rev 0\Appendices\Appendix C - Seepage and Stability Assessments\C2\[SLOPE-W Results.xlsx]Materials- Table C2.1
2. A RELATIONSHIP FOR SHEAR STRESS AND EFFECTIVE NORMAL STRESS (SU/P') WAS USED TO MODEL THE TAILINGS. THE SU/P'
VALUES USED FOR THE ANALYSES WERE 0.25 FOR STATIC AND SEISMIC LOADING DURING OPERATIONS AND 0.05 FOR LIQUEFIED
TAILINGS.
1. A RELATIONSHIP FOR FRICTION ANGLE AND EFFECTIVE NORMAL STRESS WAS DEVELOPED WAS BASED ON AVERAGE DENSITY OF
ROCKFILL (LEPS, 1970) - SEE GRAPH 1.
3) FRACTURED ROCK PARAMETERS WERE ESTIMATED USING TYPICAL PROPERTIES FOR AVERAGE QUALITY ROCK MASS (ROCK
ENGINEERING, 1995).
SourceCohesion
(MPa)Material Unit Wt. (kN/m)
Effective Friction
Ang le (deg)
AVANTI KITSAULT MINE LTD
KITSAULT PROJECT
TMF STABILITY ANALYSIS
SUMMARY OF STRENGTH PARAMETERS
Print Jan/27/2011 16:19:48
40
45
50
55
60
n
Angle,
(deg)
Graph 1: Shear Strength of Rockf ill (after Leps , 1970)
Average
20
25
30
35
40
45
50
55
60
10 100 1,000 10,000 100,000
Friction
Angle,
(deg)
Normal Stress, n (kPa)
Graph 1: Shear Strength of Rockf ill (after Leps , 1970)
Average
0 05OCT'10 GL GRGISSUED WITH REPORT VA101-343/6-2 KJB
DATE DESCRIPTION PREP'D CHK'D APP 'DREV
TABLE C2.2
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South at startup (deep seated slip circle) 1.5 1.5 OK
South at startup (shallow slip circle) 1.7 1.5 OK
South (Year 2) 1.6 1.5 OK
South (Ultimate) 1.5 1.5 OK
Northeast (Ultimate) 2.1 1.5 OK
South (Year 2) 1.6 1.2 OK
South (Ultimate) 1.5 1.2 OK
Northeast (Ultimate) 2.1 1.2 OK
Print Jan/27/11 16:21:05
AVANTI KITSAULT MINE LTD
KITSAULT PROJECT
TMF STABILITY ANALYSIS
Static
Static
Post liquefaction
Post liquefaction
Post liquefaction
Static
Static
Static
Section
FACTOR OF SAFETY SUMMARY
ResultRequired
FoS2FoS
1Loading Condition
NOTES:
1. FACTOR OF SAFETY CALCULATED USING SLOPE/W (MORGENSTERN-PRICE METHOD).
2. FOR TAILINGS EMBANKMENT ASSUMPTIONS REFER TO THE DESIGN BASIS.
M:\1\01\00343\06\A\Report\2-Tailings Storage Facility Report\Rev 0\Appendices\Appendix C - Seepage and Stability Assessments\C2\[SLOPE-W Results.xlsx]Sum
0 05OCT'10 GL GRGISSUED WITH REPORT VA101-343/6-2 KJB
DATE DESCRIPTION PREP'D CHK'D APP'DREV
C2-7 of 11
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Bedrock
Ground
El. 670
Critical Factor of Safety = 1.5
Fractured Bedrock
Waste Rock1.5Pond El. 750
Crest El. 805
1
Elevation(m
)
550
600
650
700
750
800
850
900
Criti cal Factor of Safety = 1.7
Distance (m) (x 1000)
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2500
TAILINGS MANAGEMENT FACILITYSTABILITY ANALYSIS
SOUTH EMBANKMENT - AT STARTUP
FIGURE C2.1
AVANTI KITSAULT MINE LTD
KITSAULT PROJECT
REV
0
P/A NO.
VA101-343/6
REF NO.
2
0 05OCT'10 GL GRGISSUED WITH REPORT KJB
DATE DESCRIPTION PREP'D CHK'D APP'DREV
C2-8 of 11
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Bedrock
GroundEl. 670
Tailings
Fractured Bedrock
Critical Factor of Safey = 1.6
Waste Rock
1.5
Pond El. 800 Crest El. 805
1
Elevation
(m)
550
600
650
700
750
800
850
900
TAILINGS MANAGEMENT FACILITY
STABILITY ANALYSIS
SOUTH EMBANKMENT - YEAR 2
FIGURE C2.2
AVANTI KITSAULT MINE LTD
KITSAULT PROJECT
REV
0
P/A NO.
VA101-343/6
REF NO.
2
0 05OCT'10 GL GRGISSUED WITH REPORT KJB
DATE DESCRIPTION PREP'D CHK'D APP'DREV
Distance (m) (x 1000)
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3500
C2-9 of 11
M:\1\01\00343\06\A\Data\Task 0600 (Tailings Management Facility Design)\Stability Analysis\[SLOPE-W Results.xlsx]Figure C2.3 Print 27/01/2011 12:44 PM
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Bedrock
Ground
El. 670
Tailings
Fractured Bedrock
Waste Rock
Cyclone Sand
1.5
Pond El. 856 Crest El. 861
Crit ical Factor of Safety = 1.5
1
Elevation(m)
600
650
700
750
800
850
900
TAILINGS MANAGEMENT FACILITY
STABILITY ANALYSIS
SOUTH EMBANKMENT - ULTIMATE
FIGURE C2.3
AVANTI KITSAULT MINE LTD
KITSAULT PROJECT
REV
0
P/A NO.
VA101-343/6
REF NO.
2
0 05OCT'10 GL GRGISSUED WITH REPORT KJB
DATE DESCRIPTION PREP'D CHK'D APP'DREV
Distance (m) (x 1000)
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3500
550
C2-10 of 11
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Bedrock
Ground El. 770
Tailings
Fractured Bedrock
Drains
Cyclone Sand
Liner
3
Pond El. 856 Cre s t El. 861
Was te Rock
Crit ical Factor of Safey = 2.1
1
Elevation(m
)
700
725
750
775
800
825
850
875
900
TAILINGS MANAGEMENT FACILITY
STABILITY ANALYSIS
NORTHEAST EMBANKMENT - ULTIMATE
FIGURE C2.4
AVANTI KITSAULT MINE LTD
KITSAULT PROJECT
REV
0
P/A NO.
VA101-343/6
REF NO.
2
0 05OCT'10 GL GRGISSUED WITH REPORT KJB
DATE DESCRIPTION PREP'D CHK'D APP'DREV
Distance (m)
0 100 200 300 400 500 600 700650
675
C2-11 of 11
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APPENDIX D
CONSTRUCTION SCOPE OF WORK AND METHODOLOGY
(Pages D-1 to D-6)
APPENDIX D
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APPENDIX D
AVANTI KITSAULT MINE LTD
KITSAULT PROJECT
TMF CONSTRUCTION EXECUTION PLAN
Section 1.0 - CONSTRUCTION SCOPE OF WORK
1.1 MOBILIZATION
The Work in this section comprises the establishment on the Site of all the temporary
accommodation, Plant and equipment necessary for the successful performance and completion
of the Work and shall include, but not necessarily limited to:
a. Assemble all necessary Plant and equipment and transport it to the Site;
b. Establish all the Contractors maintenance facilities, construction roads, temporary
workshops, office accommodation and sanitation facilities on the Site;
c. Maintain all Plant and services for the duration of the Work. The anticipated duration for the
Contractor on site is approximately 24 months; and
d. On completion of the Work, remove all Plant, temporary facilities and clean up and leave the
site in a clean and tidy condition to the satisfaction of the Owner.
1.2 STAGE 1A TMF CONSTRUCTION SCOPE OF WORK
Construction for Stage 1A will focus on the following work areas:
Pioneering construction access roads into Patsy Creek to allow for logging of merchantabletimber in the disturbance area and to allow construction of the construction water
management structures;
Construction water management;
Develop existing Patsy Dump for aggregate production; and
Construct South Embankment to elevation 725 m.
1.2.1 Pioneering Construction Access Roads and Logging
Construction access roads will be pioneered into the South Embankment footprint area
from the existing Patsy Dump to provide access to the embankment abutments and TMF
basin area for logging of merchantable timber. This access will then be used to construct
the construction water management structures.
a. Pioneer roads to the cofferdam locations and install temporary sediment and erosion
control Best Management Practices (BMPs);
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control Best Management Practices (BMP s);
b. Strip the foundation areas for the coffer dams and construct the dams to the
elevations shown;c. Install the temporary pumpstations and pipelines to transfer water from the
cofferdams through the South Embankment footprint and into Patsy Creek; and
d. Dewater the foundation along the Patsy Creek stream channel by excavating
interceptor trenches to drain ponded water to sump pumpstations and ultimately into
Patsy Creek.
1.2.3 Develop Existing Patsy Dump for Aggregate Production
Development of the existing Patsy Dump borrow area for aggregate production will
include the following activities:
a. Construct collection and diversion ditches and an exfiltration pond for sediment and
erosion control;
b. Construct haul roads from the existing Patsy Dump area to the south embankment by
upgrading the pioneer roads;
c. Establish a crushing and screening plant to produce Zone F, Zone D, Zone T, riprapbedding layer material and concrete coarse and fine aggregates; and
d. Establish an asphalt batch plant.
1.2.4 Construct South Embankment to Elevation 725 m
Construction of the South Embankment will include the following activities:
a. Clear and grub the footprint area of the embankment. Strip off topsoil and place intopsoil stockpile;
b. Remove overburden materials and existing Patsy Dump materials in the Stage 1
embankment footprint area to expose foundation bedrock;
c. Shape the bedrock foundation in the plinth area to remove any irregular protrusions
or overhangs;
d. Excavate plinth trench and clean with an air jet and slush grout rock surface. Remove
and clean weak seams and shear zones with a high air/water pressure jet and backfill
with slush grout or dental concrete. In closely jointed rock, cover with a concrete layer
of at least 10 cm;
e. Construct plinth and install anchor bars to provide uplift resistance against grouting
operations;
f Create a grout curtain to increase the length of any potential seepage paths and to
h. Construct the asphaltic core rockfill dam to elevation 725 m according to the zoning
as shown on the figures.
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g
1.3 STAGE 1B TMF CONSTRUCTION SCOPE OF WORK
Construction for Stage 1B will focus on the following work areas:
Construct access roads to the South Embankment, Northeast Embankment, and reclaim
barge from the plant site area bench;
Raise the asphalt core rockfill South Embankment from elevation 725 m to elevation 750 m;
and
Install a pump bypass system to lower water levels prior to freshet.
1.3.1 Construct Access Roads to the South Embankment, Northeast Embankment and
Reclaim Barge From The Plant Site Area Bench
The access roads right-of-way will be logged of merchantable timber. Clearing, grubbing
and topsoil will be removed and pushed into a brush barrier on the downhill side of the
right-of-way. The roadway will then be constructed by excavating to the lines and grades
shown on the figures. The majority of the roads will require drill and blast rockexcavation.
1.3.2 Raise the Asphalt Core Rockfill South Embankment from 725 m to 750 m
Construction water management will include construction dewatering activities as well as
the installation of sediment and erosion control measures as outlined below:
a. Extend the plinth trench up the abutments. Clean with an air jet and slush grout rock
surface. Remove and clean weak seams and shear zones with a high air/waterpressure jet and backfill with slush grout or dental concrete. In closely jointed rock,
cover with a concrete layer of at least 10 cm;
b. Construct plinth and install anchor bars to provide uplift resistance against grouting
operations;
c. Extend grout curtain up the abutments to increase the length of any potential
seepage paths and to generally lower the bulk hydraulic conductivity of the
weathered bedrock and structures within the rock using a single line curtain with
primary, secondary and tertiary holes;
d. Extend embankment drainage system up the abutments. Additional foundation drains
may be required to tie isolated springs and seeps within the embankment footprint
area into this main collector foundation drain; and
e Construct the asphaltic core rockfill embankment to elevation 750 m according to the
Pioneer construction access roads into the Northeast Embankment area to allow for logging
of merchantable timber in the disturbance area and to allow construction of the construction
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water management structures;
Construct water management structures; Develop rock borrow for aggregate and rockfill production;
Construct the NE1 and NE2 water management ponds; and
Construct the geomembrane faced rockfill Northeast Embankment to elevation 805 m.
.
1.4.1 Complete Construction of the Asphalt Core Rockfill South Embankment to Elevation
805m
Construction water management will include construction dewatering activities as well asthe installation of sediment and erosion control measures as outlined below:
a. Extend the plinth trench up the abutments. Clean with an air jet and slush grout rock
surface. Remove and clean weak seams and shear zones with a high air/water
pressure jet and backfill with slush grout or dental concrete. In closely jointed rock,
cover with a concrete layer of at least 10 cm;
b. Construct plinth and install anchor bars to provide uplift resistance against grouting
operations;
c. Extend grout curtain up the abutments to increase the length of any potential
seepage paths and to generally lower the bulk hydraulic conductivity of the
weathered bedrock and structures within the rock using a single line curtain with
primary, secondary and tertiary holes;
d. Extend embankment drainage system up the abutments. Additional foundation drains
may be required to tie isolated springs and seeps within the embankment footprint
area into this main collector foundation drain; and
e. Construct the asphaltic core rockfill embankment to elevation 805 m according to the
zoning as shown on the figures.
1.4.2 Pioneering Construction Access Roads and Logging
Construction access roads will be pioneered into the NE1 and NE2 water management
pond disturbance areas from the main access road to the plant site. This access will then
be used to construct the construction water management structures.
1.4.3 Construction Water Management
Construction water management will include construction dewatering activities as well as
the installation of sediment and erosion control measures as outlined below:
c. Install the temporary pumpstations and pipelines to transfer water from the
cofferdams through the Northeast Embankment footprint areas and into the
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downstream drainages.
1.4.4 Develop Rock Borrow for Aggregate and Rockfill Production
Development of the rock borrow area for aggregate production will include the following
activities:
a. Construct collection and diversion ditches and an exfiltration pond for sediment and
erosion control;
b. Construct haul roads from the rock borrow area to the Northeast Embankments byupgrading the pioneer roads; and
c. Establish a crushing and screening plant to produce Zone F, Zone D, Zone T and
riprap bedding layer material.
1.4.5 Construction Water Management
Construction water management will include construction dewatering activities as well as
the installation of sediment and erosion control measures as outlined below:
a. Pioneer roads to the cofferdam locations and install temporary sediment and erosion
control Best Management Practices (BMPs). This will include temporary bypass
pumping systems and pipelines;
b. Strip the foundation areas for the coffer dams and construct the dams to the
elevations shown; and
c. Install the temporary pumpstations and pipelines to transfer water from the
cofferdams through the Northeast Embankment footprint areas and into thedownstream drainages.
1.4.6 Construct the NE1 and NE2 Water Management Ponds
Construction of the NE1 and NE2 water management ponds will include the following
activities:
a. Clear and grub the footprint area of the structures. Strip off topsoil and place intopsoil stockpile;
b. Remove overburden materials in the pond and embankment footprint areas to
expose foundation bedrock;
c Construct the rockfill embankments according to the zoning as shown on the figures;
a. Clear and grub the footprint area of the embankment. Strip off topsoil and place in
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topsoil stockpile;
b. Remove overburden materials in the Stage 1C embankment footprint area to expose
foundation bedrock;
c. Install foundation and embankment drainage systems. Additional foundation drains
may be required to tie isolated springs and seeps within the embankment footprint
area into this main collector foundation drain;
d. Construct the rockfill embankments according to the zoning as shown on the figures;
e. Create a grout curtain to increase the length of any potential seepage paths and to
generally lower the bulk hydraulic conductivity of the weathered bedrock and
structures within the rock using a single line curtain with primary, secondary andtertiary holes;
f. Excavate grout trench and clean with an air jet and slush grout rock surface. Remove
and clean weak seams and shear zones with a high air/water pressure jet and backfill
with slush grout or dental concrete. In closely jointed rock, cover with a concrete layer
of at least 10 cm;
g. Install geosynthetic facing on upstream face of embankments; and
h. Install tapered wedge of rockfill against the geosynthetic lined embankment face.
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APPENDIX E
WATER BALANCE MODELING
(Pages E-1 to E-9)
APPENDIX E
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AVANTI KITSAULT MINE LTD
KITSAULT PROJECT
SECTION 1.0 - OPERATIONAL MONTHLY STOCHASTIC WATER BALANCE MODEL
1.1 GENERAL
A stochastic analysis was carried out on the base case monthly operational mine site water balance usingthe GoldSim software package. The intent of the modelling is to estimate the magnitude and extent of
any water surplus and/or deficit conditions in the tailings management facility (TMF) based on a range of
possible climatic conditions. The modelling timeline includes one pre-production year (Year -1), and 15
years of operation (Years 1 to 15) at a rate of 40,000 dry metric tonnes per day. The model is shown
schematically on Figure E.1 and incorporates the following major mine components:
Open Pit
Mill
Tailings Management Facility (TMF)
Waste Rock Management Facility (WRMF)
Cyclone Sand Plant, and
Low Grade (LG) Stockpiles.
Model assumptions and parameters are discussed in the following sections and summarized in Table E.1.
1.2 MODEL ASSUMPTIONS
1.2.1 Average Climatic Conditions
The base case monthly operational water balance model was developed using average estimated values
for precipitation. The MAP for the project site was determined to be approximately 2000 mm, with 45% of
the annual precipitation falling as rain and the remainder as snow. The average snowmelt distribution for
the project site was estimated to be 15% in April, 70% in May and 15% in June. The annual averagelong-term potential evapotranspiration for the Project site was estimated to be 450 mm. Complete details
of the derivation of the climate inputs for the project site are outlined in the project Engineering
Hydrometeorology Report (Knight Pisold, 2010).
the monthly mean and corresponding standard deviation values. The monthly mean and standard
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deviation values were used to develop monthly probability distributions, as required for a Monte Carlo
simulation. The distributions of monthly precipitation were modelled assuming an underlying Gammadistribution.
1.2.3 Tailings Streams
The conceptual design of the TMF is based on the assumption that approximately 95% of the tailings will
be geochemically innocuous material (bulk tailings) following pyrite separation. The remaining 5% of the
tailings comprises potentially reactive pyritic tailings that will be discharged by a separate pipeline into the
TMF.
1.2.4 Cyclone Sand Sleds
For six months of the year (July to November) the bulk tailings stream (95% of total tailings by weight) will
be used to produce cyclone sand for embankment fill. During these months, the bulk tailings stream will
be directed to the cyclone stations as slurry (estimated at 36.4% solids by weight). The cyclone
underflow (sand fraction) will be discharged from the cyclone stations as slurry (estimated at 74.4% solids
by weight) to construction cells along the downstream shell of the Northeast TMF embankment. The
cyclone overflow material (fine fraction) will be discharged directly to the TMF as slurry (estimated at
22.2% solids by weight). Water will be recovered from the sand cells to the extent possible using decant
boxes and will be pumped back to the TMF pond. Residual moisture draining from the fill in the
construction cells will be collected in the downstream seepage collection system.
1.2.5 Mill Requirements
The amount of process water required for the tailings slurry and mill processing was provided by AMEC
(email, September 23, 2010). The expected solids content (% by weight) of the tailings slurry was
assumed to be 36.4%. The modelled mine production schedule is 40,000 tpd for 15 years of the mine
life.
The majority of the process water will be supplied by the TMF reclaim system, with the remainder coming
from other sources which could include direct precipitation. The current water balance model includes a
fresh water mill requirement of 120 m3/hr. Ongoing refinements will be made to the model throughout the
feasibility design stage as additional information becomes available.
1.2.6 Pit Dewatering System
1.2.8 Water Retained in Tailings Voids
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The amount of water retained in the tailings is a function of the mine production schedule, and the drydensity and specific gravity for the tailings.
1.2.9 Reclaim Water
The volume of water available for reclaim to the mill was estimated using the TMF water balance.
The primary TMF inflows are:
Water being pumped to the TMF from the mill as part of the tailings slurry Direct precipitation and runoff to the TMF, which includes runoff from the upslope catchments,
and
Sand cells water recovery.
The primary TMF outflows are:
Water retained in the tailings
Evaporation, and
Seepage.
The water available for process use is assumed to be 100% of the difference between these inflows and
outflows.
1.3 RESULTS
Model results were used to determine the likelihood of having a surplus of water in the TMF, as illustrated
on Figure E.2. The figure presents the range of possible cumulative pond volumes available in the TMF
over the life of the mine, as defined by the 95th percentile values (5% chance of being equalled or
exceeded in any year). Overflow volume above the pond capacity of 10 million m3was assumed to be
discharged to the Water Box and ultimately to Lime Creek. The range of pond volumes can also be
thought of as the required active, or live, storage capacity of the TMF pond for a reasonably large range
of anticipated climatic conditions. For all cases, the TMF pond volume accumulates to 10 million m3and
begins to overflow to the Water Box in Year 1. The monthly variation in pond volume through the year is
fairly consistent from year-to-year. The pond volume fluctuates between approximately 8 million m3
tomaximum assumed capacity of 10 million m
3in a year. For the 95
thpercentile dry case, the pond volume
only goes below 8 million m3in Year 1.
For all scenarios, the system (including the TMF and contributing catchments) is able to supply enough
1.4 REFERENCES
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Knight Pisold (2010). Avanti Kitsault Mine Ltd., Kitsault Project Engineering HydrometeorologyReport. VA101-343/9-1, Rev 0, July 15, 2010.
TABLE E.1
AVANTI KITSAULT MINE LTD
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Print Jan/27/11 13:33:59
Component Assumption
Mean Annual Precipitation (mm) 2000
Mean Annual Lake Evaporation (mm) 450
Daily Ore Production (dry metric tonnes) 40,000
Mine Life (years) 15
Freshwater requirement (m3/hr) 120
Tailings dry density (tonnes/m3) 1.4
Bulk tailings (95% by weight)
Bulk tailings solids content (% by weight) 33%
Bulk tailings specifc gravity 2.66
Cyclone Sand (bulk tailings)
Sand fraction (underflow) used for embankment
construction35%
Fine Tailings (overflow) to TMF 65%
Cylone sand slurry solids content (% by weight) 33%
Pyritic tailings (5% by weight)
KITSAULT PROJECT
WATER BALANCE INPUT PARAMETERS
Pyritic tailings solids content by weight 33Pyritic tailings specific gravity 3.0
South Embankment Seepage (L/s)
Year 1 14
Year 3 7
Year 15 19
North Embankment Seepage (L/s) 32
Year 3 1
Year 15 14
Embankment Seepage Recycle rate 50%
M:\1\01\00343\06\A\Data\Task 0500 (Site Wide Water Balance)\TSF WBM\GoldSim\Stochastic
TABLE E.2
AVANTI KITSAULT MINE LTD
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Location Parameter Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Standard deviation (mm) 84 57 49 42 21 22 28 37 54 72 78 87
Mean (mm) 241 163 153 113 70 73 80 129 185 287 251 255
Coefficient of Variation 0.35 0.35 0.32 0.37 0.30 0.30 0.35 0.29 0.29 0.25 0.31 0.34
M:\1\01\00343\06\A\Data\Task 0500 (Site Wide Water Balance)\TSF W BM\GoldSim\Stochastic models\Results\[WBM_013.xlsx]Table_CV
NOTES:
1. COEFFICIENT OF VARIATION = STANDARD DEVIATION/ MEAN
2. THE COEFFICIENT OF VARIATION VALUES ARE BASED ON THE REGIONAL DATA RECORDED AT STEWART A AND NASS CAMP.
Project Site
(el. 650 m)Precipitation
KITSAULT PROJECT
MONTHLY STATISTICAL VALUES FOR WATER BALANCE MODELLING
Print Jan/27/11 13:33:59
0 05NOV'10 ER JGCISSUED WITH REPORT VA101-343/6-2 KJB
DATE DESCRIPTION PREP'D CHK'D APP'DREV
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TABLE E.3
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Runoff Coefficient
Year -1 Year 1 Year 7 Year 15 -
TMF Undisturbed Catchment 3.3 2.8 1.4 0.6 0.70
TMF Beach 0.0 0.1 0.2 0.3 0.70
TMF Pond 0.3 0.8 2.1 2.8 1.00
Other areas contributing to TMF 2.3 2.3 2.3 2.3 0.70
Open Pit 0.0 0.1 0.6 1.1 0.90
Undisturbed OP Catchment 1.4 1.4 0.9 0.3 0.70
East Waste Rock Management Facility 0.0 0.1 0.4 0.9 0.80
LocationArea (km
2)
KITSAULT PROJECT
WATER BALANCE CATCHMENT AREAS
Low Grade Stockpile 0.0 0.0 0.2 0.3 0.80
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0 14DEC'10 ER JGCISSUED WITH REPORT VA101-343/6-2 KJB
DATE DESCRIPTION PREP'D CHK'D APP'DREV
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Number Description
1 Direct Precipition on
2 Open Pit Catchment
3 Pit Dewatering to Lim
4 Fresh Water Make-u
5 Reclaim Water from
6 TMF Pond Evaporati
FRESHWATER
SOURCE21
4
FRESHWATER
SOURCE21
4
FRESHWATER
SOURCE21
4
FRESHWATER
SOURCE21
4
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p
7 TMF Catchment Run
8 TMF Seepage Collec9 TMF Seepage
10 Water trapped in the
11 Tailings from Mill
12 Pyritic Tailings to TM
MILL
CYCLONE
SANDPLANT
OPEN PIT11
13
14
13 Bulk Tailings to Sand
14 Cyclone Overflow to
15 Cyclone Sand Under
16 Process Water to Sa
17 Water from Sand Ce
18 Water Recycle from
19 TMF Surplus to Wate
MILL
CYCLONE
SANDPLANT
OPEN PIT
76
3
5
11
12
13
14
15
18
16
MILL
TAILINGS MANAGEMENTFACILITY
CYCLONE
SANDPLANT
OPEN PIT
76
3
5
11
12
13
14
15
17
18
8910 AVANTI KIT
16
19
MILL
TAILINGS MANAGEMENTFACILITY
CYCLONE
SANDPLANT
OPEN PIT
76
3
5
11
12
13
14
15
17
18
8910
0 14DEC'10 ISSUED WITH REPORT ER JGC KJB
DATE DESCRIPTION PREP'D CHK'D APP'DREV
TAILINGS MANAGEMENT FAC
AVANTI KIT
KITSAU
16
NOTES:
1. DASHED LINES ILLUSTRATE WATER FLOW PATHS DURING SAND PLANT OPERATION FROM JULY TO NOVEMBER, WHEN BULK TAILINGS ARE
DIRECTED TO THE SAND PLANT.
2. DURING DECEMBER TO JUNE, TAILINGS ARE DIRECTED TO THE TMF; 95% BULK TAILINGS AND 5% PYRITIC TAILINGS.
19
E-8 of 9
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10
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4
6
8
Volume
(Mm3)
TMF Pond - 95th Percentile Dry
TMF Pond - Median
TMF Pond - 95th Percentile Wet
Overflow - 95th Percentile DryOverflow - Median
Overflow - 95th Percentile Wet
0
-1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Year of Operation
TAILINGS MANAGEMENT FACILITYMONTHLY WATER BALANCE POND VOLUME
FIGURE E.2
AVANTI KITSAULT MINE LTD
KITSAULT PROJECT
REV0
P/A NO.
VA101-343/6REF NO
2
0 11JAN'11 ISSUED WITH REPORT ER JGC KJB
DATE DESCRIPTION PREP'D CHK'D APP'DREV
NOTE:
1. MAXIMUM TMF POND VOLUME ASSUMED TO BE 10 MILLION M3. EXCESS WATER OVER THEMAXIMUM POND VOLUME ASSUMED TO BE DISHCARGED TO THE WATERBOX.
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APPENDIX F1
BASIS OF ESTIMATE FOR FEASIBILITY STUDY
(Pages F1-1 to F1-19)
APPENDIX F
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AVANTI KITSAULT MINE LTDKITSAULT PROJECT
BASIS OF ESTIMATE FOR FEASIBILITY STUDY
SECTION 1.0 - INTRODUCTION
1.1 PROJECT DESCRIPTION
The Kitsault Project is a proposed re-development of a historical Molybdenum mine located in
northwestern British Columbia. Avanti Kitsault Mine Ltd. (Avanti) acquired the Kitsault Property in
October 2008 and has reactivated the project. Evaluation is underway for a proposed 40,000 tonnes-per-
day mine development with conventional crushing, grinding and flotation processes. Knight Pisold Ltd.
(KP) has been commissioned to develop the feasibility design for the Tailings Management Facility (TMF)
and water management systems. This document summarizes the cost estimate for the proposed design.
The Tailings Management Facility (TMF) has been designed for secure and permanent storage of alltailings from the proposed mining operations in an impoundment created by two embankments
constructed with a combination of local borrow materials, waste rock and cyclone sand from the mining
operation.
1.2 PURPOSE OF ESTIMATE
This appendix presents the feasibility level cost estimate for the TMF and site wide water management
systems. The purpose is to estimate the capital (initial and sustaining) and operating expenditures overthe life of mine for the TMF and water management systems.
1.3 ESTIMATE METHODOLOGY
The cost estimate of the TMF and water management systems was broken down into the following
elements:
General Site Preparation
Roadso Service Roads
o Temporary Haul Roads
Tailings Management Facility
o Surface Run-Off Diversion Systems
o Seepage Collection and Sediment Control Ponds
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North Water Management Ponds South Water Management Pond
Low Grade Stockpile Seepage Collection Pond
o Clary Lake Fresh Water Supply System
In general, a scope of work was developed for each major element of the work breakdown structure
(WBS) and a number of work activities were identified to achieve the scope. Where sufficient detail
existed, estimates of quantities and unit costs were developed for a work activity, and multiplied to arrive
at the estimated cost. Where insufficient detail existed for development of quantities and unit costs, lumpsump allowances based on historical experience were used. The cost estimate was prepared at a
feasibility level with a target level of accuracy of +20% / -20%. The estimate is calculated in 2010
Canadian dollars with no allowance for escalation beyond that time.
The earthworks cost component of the TMF and water management systems, including roads, and
diversion systems, were prepared by estimating the size and production rate of an appropriate equipment
fleet. Assumptions regarding the location of the various construction materials, such as borrows, quarries
or waste rock from the Open Pit were incorporated in the earthworks estimates. In addition, similar
techniques were used to develop unit rates for construction of site roads required for the TMF and water
management systems. All TMF Earthworks and Foundation Preparation, Tailings / Borrow Roads,
Diversion Systems, and Seepage Collection and Sediment Control costs were included as either initial or
sustaining capital costs in the estimate. Sustaining capital generally consisted of construction activities
necessary to raise the TMF embankments.
The capital (initial and sustaining) cost estimates for the Tailings Disposal and Reclaim, Surplus Water
System and Fresh Water Supply, collectively referred to as Pipeworks, were generally estimated based
on a mixture of vendor quotes and historical experience for similar work. Percentage based mark-ups for
manpower and equipment were applied to the material costs to cover installation. Operating costs for
Pipeworks included power and maintenance costs. Power was estimated based on pump sizes and a
unit rate for power ($ per MWh). Annual maintenance costs were estimated as a percentage of the
material component of the capital cost for the various components of the Pipeworks.
1.4 ESTIMATING TEAM
The estimating team included the following:
Greg Smyth, Senior Project Manager
Lead estimator
Quantities for Diversion Systems
Abbas Nasiri, Senior CAD Technician
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Earthworks Quantities
1.5 OUTLINE OF BASIS OF ESTIMATE
This basis of estimate is broken down into seven sections. Section 1 is the introduction, and Section 2
covers general aspects of the cost estimate, including indirects and assumptions / exclusion and
allowances common to the various elements of the cost estimate. The remaining sections are broken
down according to:
Section 3: Site Roads
Section 4: Pipeworks
Section 5: TMF Embankment Earthworks
Section 6: Water Management Ponds
Section 7: Diversion Channels
SECTION 2.0 - GENERAL
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2.1 GENERAL
This section summarizes cost bases and assumptions/exclusions that are common to the majority of the
work activities estimated for the TMF and water management systems.
2.2 COST BASIS
2.2.1 Labour
Cost for contractor labour was based on a blended labour rate of $92 per hour provided by AMECand includes salary, benefits, scheduled overtime, supervision, allowance for small tools, office
overhead and profit.
2.2.2 Equipment
Where applicable, equipment rates were referenced from the 2010-2011 BC Blue Book
Equipment Rental Rate Guide produced by the BC Road Builders and Heavy Construction
Association. These rates include all ownership costs, insurance, repairs, and contractor profit.The rates used do not include the equipment operator costs, as this was handled separately.
2.2.3 Power
A unit rate of $40/MWh was used for estimating the power portion of the annual operating
expenditures of the pump-stations.
2.2.4 Indirects
Indirects for the cost estimate included Construction Indirects, Engineering and Procurement, and
Construction Management.
Construction indirects include:
Overhead staff and support facilities
Bonding/insurance
Health and safety Environmental monitoring and incidental sediment control
Temporary site security
Maintenance of construction roads, and
P itti f
Surveillance for Dam Safety.
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Construction management includes the following items: Contract administration, including acceptance and management of change orders
Schedule management
Management of subcontractors
Project controls (project management and support), and
Field office, vehicles and living expenses from construction management staff.
Construction Indirects were estimated as a fixed percentage of 8% of the direct costs of the TMF
and Water Management costs based on past experience with similar work. Engineering and
Procurement, as well as Construction Management, was estimated based on the duration and
scope of the work, using other recently proposed or completed projects of similar scope and
duration.
No mark-up for indirects was applied to operating expenditures.
2.2.5 Contingencies and Management Reserve
The following contingencies were applied to the direct costs of the various estimate sections to
cover unforeseeable events and uncertainties due to inadequacies in project scope definition and
to reflect the level of engineering design completed for this feasibility level estimate:
General Site Preparation 10%
Roads 25%
TMF Earthworks and Foundation Preparation 25%
Tailings Disposal and Reclaim 10% Seepage Collection and Sediment Control 10%
Low Grade Stockpile 10%
Diversion Systems 25%
Fresh Water Supply 10%, and
Indirects 5%.
No allowance for management reserve to address changes in scope was included in the
estimate. It is understood that a project-wide contingency may be used to replace that which is
estimated here, to be determined by AMEC & Avanti.
2.2.6 Allowances
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SECTION 3.0 - SITE ROADS
3.1 SCOPE OF WORK
Site roads include the construction of temporary haul roads for the initial embankment construction and
construction of the permanent pipeline service roads. Cost components include:
Clearing and grubbing of road corridors.
Stripping of organics and topsoil. Construction of temporary haul roads using a dozer from the existing Patsy Waste Dump to the south
embankment (Stages 1A and 1B).
Construction of a temporary haul road from the edge of the open pit to the south embankment (Stage
1C), construction using a dozer, with some drill and blast and balancing of cuts and fills.
Construction of a temporary haul road for the construction of the Northeast starter embankments
(Stage 1C) using a dozer.
Grubbing and removal of topsoil along the service road corridors.
Construction of the pipeline service roads in rock by drilling and blasting and balancing of cuts andfills.
Processing, stockpiling and spreading a crushed pit rock wearing course on all pipeline services
roads.
Construction and armouring of stream crossing locations.
3.2 COST BASIS
Temporary haul road construction within the existing Patsy Waste Dump and the area near the
Northeast starter embankment was estimated by assuming the use of a CAT D10 Dozer to move
material. Production rates were referenced from the CATEPILLAR Handbook. Correction factors to
account for climatic conditions and material type were applied to the ideal dozer production assuming
a D10 with an average distance of 60 m pushes (twice the width of the haul road).
Grubbing operations were estimated using a production rate of 1 hectare per 12 hour shift, with an
equipment fleet consisting of an excavator, dozer and three 40 tonne trucks. Grubbed stumps and
logging remnants are assumed to be stockpiled and burned. Stripping of organics and topsoil is assumed to be performed by a 200 HP dozer with an average
production rate of 200 m3/hr, pushing material to localised stockpiles or windrow.
Drill and blasting costs were estimated using a quote received from Pacific Drilling and Blasting in the
spring of 2010 in $/BCM (Bank Cubic Metre)
Wearing course costs include drilling and blasting in the open pit, costs to operate a screening plant
(with waste factor included) and placement costs. Placement costs include loading, hauling and
l i i 3 5 k h l f th it d l t i CAT 740 t k
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placing assuming an average 3.5 km haul from the open pit, and placement using a CAT 740 truckand grader.
3.3 ALLOWANCES
A $10,000 allowance per stream crossing was included for the pipeworks access roads.
An allowance of $100 per metre was included for road barriers on the pipeworks roads, for safety
berms and to confine movement of the pipelines.
3.4 ASSUMPTIONS AND EXCLUSIONS
3.4.1 Assumptions
Quantity estimates assume all materials excavated for the Open Pit/TMF haul road was used
as road fill material and is assumed to be non-Potentially Acid Generating (non-PAG). All
additional fill for the road was obtained from the Open Pit (non-PAG waste rock).
Roads for pipeworks were estimated assuming 100% constructed through rock requiringdrilling and blasting.
Screening and stockpiling losses were assumed to be 20%.3.4.2 Exclusions
Closure costs for haul roads.
Mining and haul costs for waste rock utilized in haul roads.
Maintenance costs, including grading, snow clearing and resurfacing.
SECTION 4.0 - PIPEWORKS
4.1 SCOPE OF WORK
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This section accounts for costs associated with the TMF and water management pipeworks including the
supply and install of all pipes, valves, fittings, pipe anchoring, pumps, pump stations and electrical
interconnection for the following systems:
Bulk Tailings Distribution System
Cleaner Tailings Distribution System
Cyclone Sand Distribution System Reclaim water system
Surplus water system
Northeast Embankment Seepage Collection System
South Embankment Seepage Collection and East Waste Rock Dump Run-Off System
Clary Lake Fresh water system
Low Grade Stockpile run-off system
4.1.1 Bulk Tailings Distribution
Bulk tailings from the mill are discharged through a bulk tailings pipeline into the TMF. The flow is
by gravity. Discharge from the pipelines into the TMF is through large diameter knife gate valves
installed at intervals around the TMF South and Northeast embankment crests. With each
embankment raise, the lines are also raised, extended as required and provided with additional
spigots as appropriate. Tailings discharge is managed to develop and maintain beaches against
the embankment and sections along the south and northeast sides of the TMF.
4.1.2 Cyclone Sand Distribution System
Cyclone sand distribution will occur via two cyclone sand sled systems and pipelines along the
Northeast Embankment and one cyclone sand sled system and pipeline along the South
Embankment. Discharge from the pipelines into the TMF is through large diameter knife gate
valves installed at intervals around the TMF South and Northeast embankment crests. With each
embankment raise, the lines are also raised, extended as required, and provided with additional
spigots as appropriate. Cyclone sand discharge is managed to develop and maintain beaches
against the embankment and sections along the south and northeast sides of the TMF.
4.1.3 Reclaim Water System
4.1.4 Surplus Water System
Throughout the year surplus water from the TMF will be released into Lime Creek, either directly
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or after treatment. The surplus water will be pumped from a secondary pump on the floating
barge pump-station via a pipeline to the top of the south embankment, where the water will then
flow by gravity to the water box and from there down to Lime Creek for release.
4.1.5 Northeast Embankment Seepage Collection System
Seepage, surface runoff and supernatant water from the cyclone overflow from the Northeast
embankment will be collected via two water management ponds and pumped back into the TMFvia separate pipelines. Each pond location will contain a pump-station and necessary controls for
operation.
4.1.6 South Embankment Seepage Collection and East Waste Rock Dump Run-Off System
Seepage through the South embankment and run-off from the east waste rock dump pile will be
collected via a water management pond downstream of the South Embankment. Water will be
pumped from a pump-station to either the TMF or allowed to overflow to the Patsy Creekdiversion system in the south wall of the Open Pit.
4.1.7 Clary Lake Fresh Water System
A single fresh water pipeline connects Clary Lake to a freshwater tank at the mill to provide clean
water for process use, fire water and potable water. An intake structure and a fixed pump-station
are required at the lake.
4.1.8 Low Grade Stockpile Run-Off System
Run-off from the low grade stockpile will be collected in a small pond and pumped via a single
pipeline to the water box before release into Lime Creek.
4.2 COST BASIS
Production installation rates, crew sizes and equipment for the installation of steel pipelines, valves
and fittings is based on data from the 2010 RS Means Heavy Construction Cost Data Book and past
KP job experience.
P d ti i t ll ti t f th i t ll ti f HDPE i li i b d t i l b tt f i
Production installation rates, crew sizes and equipment for the installation of butterfly and gate valves
is based on data from the 2010 RS Means Heavy Construction Cost Data Book and past KP job
experience
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experience. Material prices for steel pipe and steel fittings of standard wall thickness are based on quotes
received from ACORN Commerical Trading limited in September 2010. An additional 10% was
added to these quotes to cover freight to the project site.
Material prices for HDPE pipe are based on quotes received from KWH pipe in September 2010. An
additional 10% was added to these quotes to cover freight to the project site.
Material and supply prices for HDPE pipe fittings is based on 2010 RS Means cost data with an
applied location factor to Prince George and a $1.03 USD to CAD exchange rate.
Material and supply prices for butterfly and gate valves is based on 2010 RS Means cost data with anapplied location factor to Prince George and a $1.03 USD to CAD exchange rate.
Supply and install of the Reclaim and Surplus Floating Barge Pump-System is based a quote
received from Chamco Industries Ltd. The quote from Chamco includes supply, installation and
commissioning of the system including all electrical interconnection (transformer and controls).
Cyclone sand system quantities and sled costs were received in an engineers estimate by Paterson
and Cooke.
Supply and install costs for water pumps (seepage collection and fresh water supply) were estimated
using October 2010 material quotes, an assumed 15% freight charge, an install production of 1 pump
per shift, with a crew size of 3 labour, 1 pipefitter and 1 operator for a CAT 966 loader.
Pumpstation civil works were estimated based on similar experience from past projects. The
estimates account for the construction of concrete foundations, a control house, a concrete sump, an
inlet pipe and minor earthwork operations.
Operating expenditures were estimated based on a fixed percentage of capital costs to cover
maintenance and operation of the various components. The fixed percentages were 10% for pipes,
valves and fittings and 7.5% for pump-stations (excluding civil works). Annual power usage was calculated assuming the pump-stations would be running 92% of the time.
4.3 ALLOWANCES
An allowance for reinforced concrete guide blocks spaced every 100 m was included in the estimate.
The concrete quantity is based on the pipe diameter and a minimum of 30 cm concrete thickness
surrounding the pipe in a cube. Quantities of pipe fittings for elbows, tees and weld caps were approximated, as no bill of quantities
existed at the time of the estimate.
Lump sum allowances were made to estimate the costs for the inlet box, drain valve, holding tank,
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5.1.1.4 Filter/Transition Zone
The filter/transition zone was calculated as 0.5 m thick on either side of the asphaltic core. Material will
be processed from blasted pit rock in a screening plant located in the open pit. The estimate containscosts to drill and blast pit rock process stockpile and load haul place spread and compact the
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p p g p p pcosts to drill and blast pit rock, process, stockpile and load, haul, place, spread and compact the
filter/transition zone.
5.1.1.5 Zone C Rockfill
Initial rockfill quantities for the south embankment will be sourced from the existing Patsy Waste Dump
located just downstream of the embankment, afterwards material will be sourced from blasted rock in the
open pit. The estimate includes costs to load, place, haul, spread and compact material sourced from the
Patsy Waste Dump and costs to spread and compact the material sourced from the open pit. Costsassociated with transporting to the embankment site is under AMECs scope of the project cost estimate.
5.1.1.6 Dam Raises
During mine production the south embankment crest will be raised each year. Waste rock will be
transported to the embankment site under the AMEC scope of the project cost estimate. The KP
sustaining cost estimate has included items to cover the spreading of cyclone sand quantities and the
processing, stockpiling, loading, hauling, spreading and compacting of a filter/transition zone. In addition
to the earthworks, costs associated with additional sub-drainage construction have been included in the
sustaining capital costs.
5.1.2 Northeast Embankment
The northeast embankment GFRD consists of a rockfill dam with an upstream filter/transition
zone covered by an impermeable HDPE liner. The HDPE liner is anchored into a liner trench and
covered by an ice-protective layer similar to that of the filter/transition zone. An additional ice
protective layer will be placed on the HDPE liner.
5.1.2.1 Construction Dewatering
Construction dewatering for the northeast Stage 1C em