ToolFusion
📋 Case Study

Ravensworth Open Pit Coal Mine Progressive Rehabilitation & Capillary Barrier System

Accelerated rehabilitation on haul road embankments and pit walls exposed to high rainfall intensity (>150 mm/hr)

🏗️ Project Overview

New South Wales, Australia – active open-cut thermal coal operation

🎯 Challenge

Accelerated rehabilitation on haul road embankments and pit walls exposed to high rainfall intensity (>150 mm/hr)

🔧 Design Approach

Layered capillary break system: 0.5 m coarse sand layer over compacted clay liner (k < 1×10⁻⁷ cm/s), topped with engineered topsoil and native grasses

📐 Design Diagram

Ravensworth Open Pit: Capillary Barrier SystemCoarse Sand Drainage Layer (k ≥ 1×10⁻⁵ cm/s)Compacted Clay Liner (k < 1×10⁻⁷ cm/s)Engineered Topsoil + Native Grassesh = 0.42 m(Capillary Break)0.5 m0.2 mRainfall >150 mm/hrChallengeHaul Road Embankment / Pit Wall

AI-generated project design illustration

📐 Key Calculations

Capillary Break Thickness

h = (2σ cosθ)/(ρg r)
Result: 0.42 m
Theoretical minimum to prevent upward water migration

Drainage Layer Permeability Requirement

k_drain ≥ 10 × k_clay
Result: ≥1×10⁻⁵ cm/s
Ensures lateral drainage without saturation buildup

📊 Results

Zero erosion gullies observed over 5 wet seasons; vegetation survival >92%; slope stability FoS >1.5 under saturated conditions

💡 Lessons Learned

  • •Field-compacted clay density must be verified via nuclear gauge
  • •Coarse sand layer requires geotextile separation from underlying fines
  • •Progressive rehab must align with haulage sequencing to avoid re-contamination

✅ Key Takeaways

  • 1Field-compacted clay density must be verified via nuclear gauge
  • 2Coarse sand layer requires geotextile separation from underlying fines
  • 3Progressive rehab must align with haulage sequencing to avoid re-contamination