1️⃣ Introduction
Mine closure marks the final phase of the mining lifecycle, ensuring that the mined-out land and water bodies are safe, stable, and environmentally sustainable. The Mineral Conservation and Development Rules (MCDR) 2017 and DGMS guidelines mandate scientific closure, including water reclamation, pit lake formation, slope stabilization, and long-term environmental monitoring.
2️⃣ Objectives of Mine Closure
- Ensure long-term stability of land and slopes.
- Prevent water pollution and uncontrolled seepage.
- Convert mine pits into safe reclaimed lakes or productive land.
- Protect local hydrogeological balance.
- Promote biodiversity and community development.
3️⃣ Statutory Framework for Mine Closure
| Regulation / Rule | Authority | Key Provision |
|---|---|---|
| MCDR 2017 – Rule 23C | IBM | Progressive & Final Mine Closure Plans mandatory. |
| MMR 1961 / CMR 2017 | DGMS | Safety in slope and water handling. |
| Environment (Protection) Act, 1986 | MoEFCC | Pollution control and reclamation obligations. |
4️⃣ Post-Mining Water Management
After mining ceases, proper hydrogeological study is essential to design a safe pit lake or reclaimed water body. This involves assessing inflow sources, evaluating pit geometry, deciding the end-use, and installing overflow systems to ensure water quality compliance.
5️⃣ Pit Lake Design & Safety
Pit lakes are a preferred reclamation strategy. Key design parameters include:
- Side slope: < 30° for stability.
- Depth: Usually 30–50 m (safe zone).
- Freeboard: 1.5–2 m for overflow safety.
- Fencing: Mandatory to prevent unauthorized access.
- Water Quality: pH 6.5–8.5, TSS < 100 mg/L, no heavy metal contamination.
6️⃣ Slope Stabilization and Land Reclamation
Unstable slopes are reshaped to gentle gradients (27°–30°), compacted, and covered with topsoil and native vegetation to control erosion. Techniques include bench slope flattening, toe drains, and geo-textile reinforcement.
7️⃣ Progressive vs. Final Closure
- Progressive Mine Closure Plan (PMCP): Implemented during mining for concurrent reclamation.
- Final Mine Closure Plan (FMCP): Implemented post-mining for rehabilitation of the entire area.
⚡ Quick One-Liners (Revision Points)
- Rule 23C of MCDR 2017 mandates Mine Closure Plans.
- Pit lake slope < 30° ensures stability.
- FMCP is approved by IBM before mine closure.
- DGMS regulates safety during closure activities.
- pH of pit lake should be between 6.5–8.5.
- Topsoil must be preserved for reclamation.
- Constructed wetlands aid natural water treatment.
- Phytoremediation uses plants to clean water.
🧠 Descriptive Model Answer
Q. Discuss post-mining water management and reclamation strategies as per DGMS and MCDR 2017.
Answer: Under MCDR 2017 Rule 23C, every mine must implement a Progressive and a Final Mine Closure Plan. Post-mining water management includes the safe handling of accumulated water in pits, often by creating stable pit lakes with gentle slopes (<30°), lined bottoms, and controlled overflow structures. Water reclamation focuses on sedimentation, filtration, and biological treatments like constructed wetlands. DGMS ensures safety in all closure operations. This approach ensures environmental compliance, long-term water safety, and community benefit through sustainable land and water reuse.
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