ToolFusion
πŸ“‹ Case Study

Cadia Valley Copper-Gold Mine Bio-Integrated Landform for Waste Rock Dump Closure

Steep, unvegetated waste rock dumps with acid-generating potential and high erosion risk

πŸ—οΈ Project Overview

New South Wales, Australia – large-scale porphyry copper-gold operation

🎯 Challenge

Steep, unvegetated waste rock dumps with acid-generating potential and high erosion risk

πŸ”§ Design Approach

Geomorphic landform sculpting (≀20Β° slopes) with engineered soil profile: 0.3 m root zone (pH 6.2, OM 5%), 1.2 m moisture-retentive subsoil, 0.5 m capillary break, and 2.0 m inert rock core

πŸ“ Design Diagram

2.0 m inert rock core 0.5 m capillary break 1.2 m moisture-retentive subsoil 0.3 m root zone (pH 6.2, OM 5%) ≀20Β° slope (19.3Β° erosion limit) ΞΈ_sat βˆ’ ΞΈ_wp = 0.28 mΒ³/mΒ³ Inert core Capillary break Engineered soil Slope constraint Cadia Valley Bio-Integrated Landform Waste Rock Dump Closure Design

AI-generated project design illustration

πŸ“ Key Calculations

Erosion Limit Slope Angle

tan⁻¹(Critical Shear Stress / Soil Unit Weight)
Result: 19.3Β°
Maximum stable angle under design rainfall return period

Root Zone Water Holding Capacity

ΞΈ_sat βˆ’ ΞΈ_wp
Result: 0.28 mΒ³/mΒ³
Supports 90-day drought survival for native species

πŸ“Š Results

98% ground cover achieved within 18 months; zero runoff sediment load measured at toe; no ARD detected in leachate (pH >6.5, Fe <0.5 mg/L)

πŸ’‘ Lessons Learned

  • β€’Landform geometry must accommodate future subsidence without ponding
  • β€’Root zone must be placed before monsoon season
  • β€’Micro-topography (swales, berms) enhances seed retention and infiltration

βœ… Key Takeaways

  • 1Landform geometry must accommodate future subsidence without ponding
  • 2Root zone must be placed before monsoon season
  • 3Micro-topography (swales, berms) enhances seed retention and infiltration