Design, Control & Monitoring of Pit and Dump Slopes in Opencast Mines – DGMS Guidelines & Safety Measures

🧾 DETAILED NOTES

1️⃣ Introduction

Pit and dump slope stability is a crucial factor in ensuring safe and efficient opencast mining operations. Any slope failure may cause accidents, equipment loss, or production delays. DGMS emphasizes proper design, control, and continuous monitoring of pit and dump slopes under Regulations 106 & 107 of CMR 2017 and relevant DGMS Technical Circulars.

2️⃣ Slope Design Principles

Bench Height: ≤ 10 m (as per geotechnical design).
Bench Width: ≥ 3 times equipment width or ≥ 10 m (whichever is greater).
Overall Slope Angle: ≤ 28° for OB dumps; varies based on strata.
Safety Factor (FOS): ≥ 1.3 under static, ≥ 1.1 under seismic conditions.
Design Approval: Must be done by a qualified geotechnical engineer and approved by DGMS.

3️⃣ Causes of Slope Failure

Weak strata or clay layers at the base.
Excessive height and steep slopes.
Poor drainage and water accumulation.
Vibrations from blasting and machinery.
Lack of monitoring and maintenance.

4️⃣ DGMS Regulations

Reg. 106 (CMR 2017): Construction and maintenance of OB dumps.
Reg. 107 (CMR 2017): Precautions against slope and dump failure.
DGMS Tech. Circular 7 of 2014: Slope design and monitoring guidelines.
Circular 1 of 2012: Mandates geotechnical studies and regular review.

5️⃣ Monitoring Techniques

Visual Inspections: Regular patrol by safety and geotechnical staff.
Survey Measurements: Using Total Station, GPS, and drones.
Instrumentation: Piezometers (pore water pressure), Inclinometers (movement detection), Extensometers (surface displacement), Prism targets (slope movement).
Remote Monitoring: Radar and LiDAR systems for real-time slope tracking.

6️⃣ Drainage & Control Measures

Garland drains around dump toe and top.
Catch drains to divert stormwater.
Toe walls and retaining structures.
Progressive compaction of dump layers.
Vegetation cover to reduce erosion.

7️⃣ Responsibilities

Mine Manager: Ensure implementation of slope design and maintenance.
Geotechnical Engineer: Regular monitoring and data interpretation.
DGMS: Periodic inspection and design approval.

8️⃣ Case Example

In 2019, a slope failure in a large opencast coal mine resulted in major loss. Investigation revealed absence of toe drains and improper bench configuration. DGMS reinforced mandatory slope monitoring as per Circular 7 of 2014.

⚙️ QUICK ONE-LINERS (Revision Points)

Reg. 106 & 107 – Slope and dump safety.
Max slope angle: 28° (OB dumps).
FOS ≥ 1.3 (static condition).
Drainage is vital for slope stability.
Monitoring by geotechnical engineer mandatory.
Piezometer and prism – key instruments.
Dump failures are most common after heavy rain.
Design approval needed from DGMS.
Circular 7/2014 – Slope stability study.
Garland drains prevent toe erosion.

🧮 DESCRIPTIVE MODEL QUESTION

Q. Explain the design, control, and monitoring measures of pit and dump slopes in opencast mines as per DGMS guidelines.

Answer:
Pit and dump slopes must be scientifically designed and continuously monitored to prevent slope failure. DGMS under CMR 2017 Reg. 106 & 107 mandates geotechnical analysis, slope angle restriction, and drainage management. Monitoring includes visual inspections, use of instruments like piezometers and prisms, and maintaining a factor of safety ≥ 1.3. Regular inspections, record keeping, and adherence to Circular 7/2014 ensure safe operations and prevent accidents.

🧩 25 DGMS-Based MCQs (Dynamic Answers – A–E)

Q1. Regulation dealing with slope stability in opencast mines:

Solution: Regulation 106 of CMR 2017 specifically covers the construction and maintenance of OB dumps and slope stability.

Q2. Maximum overall slope angle for OB dump:

Solution: 28° is the commonly cited safe overall slope angle for overburden dumps under standard conditions.

Q3. Factor of safety for slope design should be:

Solution: A minimum Factor of Safety of 1.3 is required for long-term static stability.

Q4. The key DGMS circular for slope stability:

Solution: DGMS Technical Circular 7 of 2014 provides comprehensive guidelines for dump stability analysis.

Q5. Instrument used for slope movement detection:

Solution: All these instruments are used: Piezometers (water pressure), Extensometers (displacement), and Clinometers (angle changes) all help detect instability.

Q6. Primary cause of slope failure:

Solution: Geotechnical weakness (weak strata) and high water pressure (poor drainage) are the primary drivers of slope instability.

Q7. FOS under seismic condition must be at least:

Solution: Under dynamic (seismic/earthquake) loading, a slightly lower FOS of 1.1 is often considered acceptable.

Q8. Bench height in opencast mine should not exceed:

Solution: 10 m is a common maximum bench height for OB dumps, though pit bench height depends on the excavator's reach.

Q9. Bench width must be:

Solution: This guideline (or 3x dumper width for haul roads) ensures safe movement and berm placement.

Q10. DGMS mandates slope monitoring by:

Solution: Slope stability is a specialized field requiring a qualified Geotechnical Engineer.

Q11. Cracks on slope indicate:

Solution: Tension cracks are a clear visual warning sign that the slope is under stress and may be failing.

Q12. Slope failure often occurs after:

Solution: Rainfall (saturation) and overloading are both major triggers that reduce stability and can cause failure.

Q13. The purpose of garland drains is:

Solution: Garland drains are built around the dump to intercept surface runoff water and divert it away from the slope.

Q14. Safe dump height depends on:

Solution: All these geotechnical factors must be considered in designing a safe dump height.

Q15. Monitoring frequency (visual inspection) should be:

Solution: Weekly inspections by competent persons are a standard requirement, with more frequent checks during/after rain.

Q16. Instrument measuring pore pressure:

Solution: Piezometers are specifically designed to measure pore water pressure within soil or rock.

Q17. Dump failures are categorized under:

Solution: Slope stability is a core subject of geotechnical engineering.

Q18. Stability analysis is performed by:

Solution: Only a qualified geotechnical engineer has the expertise to conduct slope stability analysis.

Q19. Regulation 107 relates to:

Solution: Regulation 107 of CMR 2017 is titled "Precautions against failure of overburden dumps..."

Q20. Real-time slope monitoring can use:

Solution: All these technologies (LiDAR, Radar, robotic Total Stations with prisms) are used for advanced, real-time monitoring of slope movements.

Q21. Catch drain purpose:

Solution: Catch drains are built on benches or at the top of slopes to catch and divert surface runoff before it erodes the slope face.

Q22. DGMS requires geotechnical report to be:

Solution: Geotechnical reports/plans must be prepared, filed, and often approved or reviewed by DGMS, with annual updates.

Q23. Overburden dump must be designed by:

Solution: Safe dump design is a specialized task requiring a qualified geotechnical engineer or institution.

Q24. CMR 2017 came into force replacing:

Solution: The Coal Mines Regulations, 2017, superseded the earlier Coal Mines Regulations, 1957.

Q25. Slope stability factor of safety less than 1 means:

Solution: FOS < 1 indicates that the forces causing failure are greater than the forces resisting failure, meaning the slope is unstable.

🔗 INTERNAL LINKS

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Online Mining Exam

Design, Control & Monitoring of Pit and Dump Slopes in Opencast Mines – DGMS Guidelines & Safety Measures

🧾 DETAILED NOTES

1️⃣ Introduction

2️⃣ Slope Design Principles

3️⃣ Causes of Slope Failure

4️⃣ DGMS Regulations

5️⃣ Monitoring Techniques

6️⃣ Drainage & Control Measures

7️⃣ Responsibilities

8️⃣ Case Example

⚙️ QUICK ONE-LINERS (Revision Points)

🧮 DESCRIPTIVE MODEL QUESTION

🧩 25 DGMS-Based MCQs (Dynamic Answers – A–E)

🔗 INTERNAL LINKS

🏗️ Master DGMS Opencast Safety Topics!

OUR COURSES View More

📚 Daily Quiz • DGMS Prep

Design, Control & Monitoring of Pit and Dump Slopes in Opencast Mines – DGMS Guidelines & Safety Measures

🧾 DETAILED NOTES

1️⃣ Introduction

2️⃣ Slope Design Principles

3️⃣ Causes of Slope Failure

4️⃣ DGMS Regulations

5️⃣ Monitoring Techniques

6️⃣ Drainage & Control Measures

7️⃣ Responsibilities

8️⃣ Case Example

⚙️ QUICK ONE-LINERS (Revision Points)

🧮 DESCRIPTIVE MODEL QUESTION

🧩 25 DGMS-Based MCQs (Dynamic Answers – A–E)

🔗 INTERNAL LINKS

🏗️ Master DGMS Opencast Safety Topics!

OUR COURSES View More

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