Mine Closure, Rehab and TMF
Tailings dam lifts, closure provisions, rehabilitation, and milestone CapEx chart.
TMF Deposition vs Capacity
Cumulative Fill— Capacity LimitBUILD = construction start (lead = build yrs)Source: 2508kt/yr
TMF Fill Schedule (waterfall)
25Mt3Mt remBUILD TMF Lift 2 38Mt0Mt remBUILD TMF Lift 2 410Mt4Mt remBUILD TMF Lift 3 513Mt1Mt remBUILD TMF Lift 3 615Mt4Mt remBUILD TMF Lift 4 (Final) 718Mt1Mt remBUILD TMF Lift 4 (Final) FilledRemainingBuild trigger
TMF Cost Model — $/Tonne Tailings
Unit Cost = (Annual Opex + Annualized Capex) / Tonnes Deposited
Operating Costs (Opex)
Total Annual Opex$5.0M/yr
Capital Costs (Annualized)
Dam Raises (all lifts):
$45M
Closure Works:
$25M
Water Treatment:
$8M
Post-Closure:
$5M
Total Capex:
$83M
LOM Years:
15
Annualized Capex (EAC)$5.5M/yr
TMF Cost per Tonne = (Annual Opex + Annualized Capex) / Tonnes Deposited
($5.0M + $5.5M) / 2,508kt =
Total Annual TMF Cost: $10.5M (2,508kt × $4.19/t)
Closure and Rehabilitation Provisions
TMF Risk Assessment
Failure Modes
| Mode | Likelihood | Consequence | Risk |
|---|
| Overtopping | Low | Very High | High |
| Slope Failure | Low | Very High | High |
| Piping/Seepage | Medium | High | High |
| Foundation | Low | Very High | High |
| Liquefaction | Low | Very High | Medium |
| Erosion | Medium | Medium | Medium |
| Seismic | Low | Very High | Medium |
Controls & Monitoring
Piezometers12 units, 4 autoMonthly
Inclinometers6 unitsQuarterly
Survey Prisms24 prismsMonthly
Seepage Drains3 toe drainsContinuous
FreeboardMin 1.5mWeekly
Visual InspectionCrest & faceDaily
3rd Party ReviewIndependent eng.Annual
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CLOSURE - TMF LIFTS - REHAB - MILESTONE CAPEX - WATERFALL