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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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    35

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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

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    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

    M:\1\01\00343\06\A\Data\Task 0600 (Tailings Management Facility Design)\Stability Analysis\[SLOPE-W Results.xlsx]Figure C2.1 Print 27/01/2011 12:42 PM

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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

    M:\1\01\00343\06\A\Data\Task 0600 (Tailings Management Facility Design)\Stability Analysis\[SLOPE-W Results.xlsx]Figure C2.2 Print 27/01/2011 12:43 PM

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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

    M:\1\01\00343\06\A\Data\Task 0600 (Tailings Management Facility Design)\Stability Analysis\[SLOPE-W Results.xlsx]Figure C2.4 Print 27/01/2011 12:45 PM

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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

    E-6 of 9

    TABLE E.3

    AVANTI KITSAULT MINE LTD

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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

    M:\1\01\00343\06\A\Data\Task 0500 (Site Wide Water Balance)\TSF WBM\GoldSim\Stochastic models\Results\[WBM_013.xlsx]Table_areas

    0 14DEC'10 ER JGCISSUED WITH REPORT VA101-343/6-2 KJB

    DATE DESCRIPTION PREP'D CHK'D APP'DREV

    E-7 of 9

    M:\1\01\00343\06\A\Data\Task 0500 (Site Wide Water Balance)\TSF WBM\GoldSim\Stochastic models\Results\WBM_013WBM_013

    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