High Lake Project Hydrology

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High Lake ProjectHydrology Surface Water
Quality

• Eugene Yaremko,nhc
• Leslie Gomm, GLL

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HydrologyImpact Assessment

• Has followed an Issues-based approach where
  mining activities would have an impact on
•  Surface Water Quantity
• Distribution of Water

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HydrologyImpact Assessment

• Local study area vs. environmental impacts
• It has been assumed that impacts related to
  mining activities and surface water will not
  extend beyond the LSA

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HydrologyBaseline Data

• Streamflow 14 hydrometric stations
• 10 of these associated with Kennarctic River Flow
• 2 stream crossings along all-season road
• Periods of record available range from on to
  three years, beginning in 2004
• Climate station near south end of High Lake
  installed in 2004
• Temperature, rainfall, relative humidity, wind
  speed and direction

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HydrologyBaseline Data

• Snow course measurements immediately prior to
  spring freshet (2004 and 2005)
• Bathymetric surveys of primary lakes within LSA

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HydrologyRegional Assessment

• The short streamflow and climate record available
  within the LSA make it necessary to utilize
  regional information principally
• Six water survey of Canada stations
• Climate records for Lupin/Contwoyto Lake
  Kugluktuk/Copper River and Cambridge Bay. 

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HydrologyWater Balance Assessments LSA

• Three primary components in the process
• Annual precipitation
• Annual evaporation
• Coefficient of runoff

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HydrologyAnnual Precipitation

• Estimate of annual precipitation at mine site has
  to be regional information
• Three long-term climate stations were utilized
• Lupin/ Contwoyto Lake (combined) centered 250
  km south of High Lake
• Kugluktuk/Coppermine (combined) centred 170 km
  south and 50 km north of High Lake
• Cambridge Bay centred 240 km East and 175 km
  north of High Lake

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HydrologyAnnual Evaporation

• Mean Annual Evaporation for Project 240 mm
• Estimate of mean annual evaporation based on
  regional information principally
• Lupin 275 mm
• Doris North Project 220 mm
• Salmita (Reid) 286 mm
• Hydrological Atlas of Canada MAE contours

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HydrologyRunoff Coefficient

• Adopted value of 0.60
• Based on local and regional information

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Surface Water Quality

• Site Water Management - Overview
• Predicted Impacts
• 4 pathways
• Key Issues
• Assessment Approach For Kennarctic River
• Summary of Baseline
• Total vs. Dissolved Metals and TSS
• Water Quality Model
• Water Management Plan

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Site Water Management

• The following principles were used in the design
  of water-related aspects of the Project
• Minimizing the number of drainage areas
  (sub-catchments) affected by the Project by
  limiting most of the development to within the
  High Lake drainage area
• Minimizing the disturbance footprint outside of
  the High Lake drainage area
• Implementation of BMPs for the collection,
  treatment and handling of all site runoff

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Site Water Management

• Filling pits with tailings
• Routing of mill tailings, mine water, pre-treated
  deep groundwater, treated sewage, and runoff from
  the waste rock piles, mill area and buildings to
  the High Lake Tailings Impoundment
• Treatment at or near source
• Maximizing underground mine backfilling of PAG
  material
• Seasonal discharge to Kennarctic River (June
  October) with treatment if required

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Retention Time 2 to 3 Years
Ore StockPile
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Predicting Site Water Quality

• High Lake Water Quality Model
• Predict the water quality, water volumes and
  elevations in High Lake, AB Pit and D Pit
• Source loading terms for mine rock and pit walls
  based on kinetic tests
• Incorporates inputs due to explosives residues
  from mine rock and pits
• Predict water quality any discharges to receiving
  environment including the Kennarctic River, L15,
  and L4 during mine operations, closure and
  post-closure (to Year 150)
• Based on a MAP of 280 mm and MAE of 240 mm and
  run using different hydrological scenarios
  modeled including a 3 yr drought and 2 year wet
  period

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Predicting Site Water Quality

• High Lake Water Quality Model - Results
• All predicted concentrations of regulated
  parameters below MMER except zinc for first 1.5
  years
• Chloride, nitrite, aluminum, antimony, arsenic,
  cadmium, chromium, copper, lead, manganese,
  nickel, selenium, silver and zinc above
  threshold levels
• Copper, zinc and cadmium - existing lake
  conditions - decrease over time from the
  naturally high levels
• Chloride, chromium and cadmium estimated
  pre-treated inflows from underground mine
• Ammonia, nitrate and nitrite nitrogen
  explosives residues and sewage (minor)
• Selenium and other parameters primarily mill
  effluent and secondarily mine rock

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Predicting Site Water Quality

• High Lake Water Quality Model - Results
• Discharge to Kennarctic River will not occur
  until 3rd year of operations
• Treatment of discharge through polishing pond
  will be carried out to reduce metal levels in
  discharge copper, cadmium, chromium and zinc -
  where required
• Long term water cover
• High Lake - 5 m
• D-Pit - gt 10 m

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Surface Water Quality Predicted Impacts

• Surface water quality impacts were assessed using
  the following thresholds
• CCME Guidelines for the Protection of Aquatic
  Life
• Cadmium U.S. EPA Criterion Continuous
  Concentration (CC)
• Chloride U.S. EPA CCC
• Manganese - Canadian Drinking Water Guidelines
  aesthetic objective

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Surface Water Quality Predicted Impacts

• SWQ1 Project activities, including roads,
  outside immediate High Lake catchment
• Based on annual load model predicted
  concentrations above existing baseline
  concentrations but below threshold values for
  protection of aquatic life except for
• Copper in L15 within range of baseline
  concentrations

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Surface Water Quality Predicted Impacts

• SWQ2 Diversion of streams L18 to Kennarctic
  River and L15 to L4
• Permanent diversion of these streams will not
  result in any appreciable changes in water quality

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Surface Water Quality Predicted Impacts

• SWQ3 Construction of High Lake Tailings
  Facility
• Discharge of treated High Lake water during dam
  construction will not result in any changes in
  the water quality in the Kennarctic River except
  for cadmium
• Predicted cadmium concentrations are above
  background levels but below the threshold for
  protection of aquatic life

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Surface Water Quality Predicted Impacts

• SWQ4 Discharge of water from the High Lake
  Tailings Facility to the Kennarctic River
• Predicted open water season concentrations in the
  Kennarctic River immediately downstream of
  discharge are predicted to be above existing
  baseline concentrations but below threshold
  values except for copper and selenium
• Predicted under-ice concentrations (from deep
  groundwater inflows after Year 34) of selenium
  and chromium are above threshold values

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Surface Water Quality Predicted Impacts
Selenium - Other jurisdictions acknowledge
unpredictable effects with wide range of
guidelines. Body burden in fish more useful than
water concentration. Will monitor body burdens in
fish.
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Surface Water Quality Issues

• Kennarctic River
• Concerns have been raised regarding the approach
  taken for assessment of water quality impacts in
  the Kennarctic River
• The following outlines the approach taken in the
  assessment including significance determination

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Surface Water Quality Issues

• Kennarctic River Open Water Season
• Fully mixed concentrations in the Kennarctic
  River downstream of discharge are predicted to be
  above existing baseline concentrations for a
  number of COCs but below threshold values for all
  except for copper and selenium

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Surface Water Quality Issues

• Kennarctic River-Open Water
• Copper
• Max. concentration 0.0034 mg/l (LSA)
• Above CCME threshold (0.002 mg/L) for 5 years
  during operations in both LSA and RSA
• Selenium
• Max. concentration 0.002 mg/L (LSA)
• Above CCME threshold (0.001 mg/L) for 3 years
  during operations in both LSA and RSA

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Surface Water Quality Issues

• Kennarctic River-Under Ice
• Predicted under-ice concentrations (from deep
  groundwater inflows after Year 34) of selenium
  and chromium are above threshold values
• Selenium Max. concentration 0.0012 mg/l
• Above threshold (0.001 mg/L) for 6 years (May
  only) in LSA
• Chromium Max. Concentration 0.0011 mg/l
• Above threshold (0.001 mg/L) for 10 years (May
  only) in LSA

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Surface Water Quality Issues

• Kennarctic River
• Magnitude of impacts were assessed using
  following criteria

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Surface Water Quality Issues

• Kennarctic River
• Summary of Significance Rating Criteria

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Surface Water Quality Issues
Assessment of significance would not change by
making LSA smaller and having RSA start farther
upstream same magnitude (moderate) in both LSA
and RSA.
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Surface Water Quality Issues

• Plume Delineation
• Downstream distance for complete mixing of the
  High Lake discharge 230 m
• Based on a single point channel side discharge
  configuration with instantaneous vertical mixing
• Estimated that at 50 m downstream 90 diluted
• A plume delineation study will be carried out
• Modelling of High Lake discharge
• Field monitoring to calibrate and validate model
  results
• Based on plume delineation study results,
  appropriate mitigation may be implemented to
  minimize mixing zone

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Surface Water QualityIssues

• Summary of Baseline Data
• Concern that baseline data not presented
  adequately to characterize natural variability
• Zinifex will provide an updated summary and
  evaluation of the baseline water quality data set
  including
• Evaluation of temporal and spatial variability
• Additional data collected in 2006 and 2007
• Discussion of linkages to the future site AEMP

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Surface Water Quality Issues

• Total vs. Dissolved Metals and TSS
• Concerns raised of the use of dissolved metals
  for mine rock source terms under-estimates metal
  concentrations
• High Lake model
• Pits and waste rock dissolved metals
• Tailings supernatant, residual drainage, ore
  stock pile total metals
• Road model
• Road construction material - dissolved metals
• Natural drainage total metals

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Surface Water Quality Issues

• Total vs. Dissolved Metals and TSS
• This approach to modelling was adopted given
• In general, in aquatic toxicology, it is the
  dissolved metal fraction is considered to be the
  metal fraction that is bio-available and elicits
  most of any toxic effect.
• BMPs will be used on-site to minimize TSS
  loadings to the receiving environment
• Also note - that fractions estimated as
  dissolved report to tailings area but
  discharge to environment was estimated as total
  metals

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Surface Water Quality Issues

• Total vs. Dissolved Metals and TSS
• Concerns raised with modelling of road runoff
• No particulate fraction
• Assumed 15 mg/L only in first year
• Concerns also raised about use of annual load
  model

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Surface Water Quality Issues

• Total vs. Dissolved Metals and TSS
• Zinifex is committed to re-evaluating the impacts
  of metals associated with particulate matter
  including
• Assessment of the contribution of particulate
  fraction to overall loading and associated
  impacts in both models
• Sensitivity analysis of TSS loading in the road
  runoff model
• Monthly model has subsequently been developed for
  road runoff

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Surface Water QualityIssues

• WQ Model
• Predict the water quality, water volumes and
  elevations in High Lake, AB Pit and D Pit
• Predict water quality any discharges to receiving
  environment including the Kennarctic River, L15,
  and L4 during mine operations, closure and
  post-closure (to Year 150)
• Different hydrological scenarios modeled
  including a 3 yr drought and 2 year wet period
• Model originally in Stella recently transferred
  to Goldsim

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Surface Water QualityIssues

• WQ Model
• Several concerns have been raised during review
  of DEIS regarding the High Lake water quality
  model including
• Lack of rationale for selection of runoff
  coefficients
• Selection of drought/wet scenarios
• Use of average flow conditions

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Surface Water QualityIssues

• WQ Model
• Model has been update for ease of running
  scenarios to adequately characterize the system
  and run scenarios
• Highlights of Goldsim Model
• Water treatment at source (AB Pit, D Pit and ore
  stockpile)
• Desalination of deep groundwater
• Updated source loading terms from mine rock

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Surface Water QualityIssues

• WQ Model
• Highlights of Goldsim Model
• Increased AB Pit Cap and AB NAG cover from 5 m to
  10 m
• Use of thermo-siphons
• Updated estimates of deep and shallow groundwater
  seepage
• Incorporates receiving environment modelling
  including L4, L15 and the Kennarctic River
• Climate change scenario

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Surface Water QualityIssues

• Updated Model Results
• Predicted open water concentrations similar to
  previous results with same duration and extent
• 0.0032 mg/L Copper and 0.002 mg/L Selenium
• Predicted under-ice concentrations no longer
  any parameters above thresholds
• 0.0005 mg/L Chromium and 0.0009 Selenium
• Reduced impact (under ice) but no change in
  overall determination of significance
• Impacts will be further evaluated in an Aquatic
  Risk Assessment

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Surface Water QualityIssues
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Surface Water QualityIssues
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Surface Water QualityIssues
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Surface Water QualityIssues
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Surface Water QualityIssues

• Additional 100-year extreme drought scenario -
  test ability to maintain water cover
• Year 20
• 1100 return event 164 mm
• Evaporation 292 mm
• Year 21
• 150 return event 180
• Evaporation 265 mm
• Year 22
• 110 return event 216
• Evaporation 240 mm

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Surface Water QualityIssues
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Surface Water QualityIssues

• Water Management Plan
• Preliminary Water Management Plan (WMP) was
  provided as part of the DEIS which included a
  summary of
• Site water management facilities including
  treatment
• Mine rock storage plan
• Tailings management
• Predicted performance of water management systems
  (water quality and flows)
• High Lake Water Quality Model
• Monitoring

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Surface Water Quality Issues

• Water Management Plan
• Several concerns have been raised during review
  of DEIS including lack of detail on
• Rationale for assumptions
• Schematics of water management systems
• Drainage management systems including sediment
  and erosion control
• Proposed treatment systems
• Monitoring to support adaptive management and
  system performance monitoring
• Site water modelling and associated results

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Surface Water Quality Issues

• Water Management Plan
• Zinifex is committed to providing an updated
  comprehensive water management plan with
  supporting detailed model documentation to
  address these concerns

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Surface Water QualityIssues

• Additional 100-year extreme drought scenario -
  test ability to maintain water cover
• Year 20
• 1100 return event 164 mm
• Evaporation 292 mm
• Year 21
• 150 return event 180
• Evaporation 265 mm
• Year 22
• 110 return event 216
• Evaporation 240 mm

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Hydrology and Surface Water Quality