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🧠 Detailed Notes

1️⃣ Major Hazards in Highwall Mining 

 Highwall mining combines surface and underground operations, creating specific hazards that must be monitored closely.
Key hazards include:

• Slope Failure / Highwall Collapse – due to weak strata or excessive penetration depth.
• Roof & Rib Fall – within highwall entries caused by stress redistribution.
• Equipment Fire / Electrical Faults – due to high-voltage machinery.
• Gas Emission & Poor Ventilation – methane pockets in the coal seam.
• Water Inrush / Seepage – especially during monsoon or adjacent workings.
• Communication Failure – loss of remote link between operator and miner.

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2️⃣ DGMS Safety Guidelines 

The Directorate General of Mines Safety (DGMS) issues regular circulars for highwall safety.
Important Circulars:

• DGMS Tech Circular 06 of 2018: Guidelines for remote-controlled mining and slope monitoring.
• DGMS Tech Circular 03 of 2016: Maintenance of safe barrier and setback distances.
• DGMS Tech Circular 04 of 2017: Use of slope monitoring radar and SSR (Slope Stability Report).
• DGMS Circular 01 of 2020: Real-time data transmission for safety-critical operations.

Key requirements:

• SSR to be prepared by qualified geotechnical engineer.
• Real-time slope monitoring radar mandatory for all working benches.
• Setback distance ≥ height of the highwall.
• Daily inspection by manager or authorized official.

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3️⃣ Slope Stability & Monitoring

• SSR includes geology, rainfall data, FoS calculation, and radar records.
• Radar alarms must trigger automatic stop if displacement exceeds 10 mm/hr.
• Drainage: Surface drains must divert rainwater away from the highwall toe.
• Pillar stability: Recovery must maintain minimum 1.5 FoS (Factor of Safety).
• DGMS inspection every quarter ensures compliance.

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4️⃣ Case Studies

• Dudhichua Mine (NCL, 2019): Slope slip due to excessive penetration depth.
• Singareni Collieries (2017): Water inrush during monsoon due to inadequate drainage.
• SECL Dipka (2021): Highwall radar successfully warned before collapse, saving equipment.

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5️⃣ DGMS Exam Focus Points

• DGMS Circular 06/2018 → Remote mining and monitoring.
• SSR preparation standards → FoS & rainfall inclusion.
• Drainage & Setback → Safety barriers as per circular.
• Slope radar → Early warning threshold values.
• Inspection reports → Manager’s responsibility under CMR 2017.

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🧩 MCQs (Q1–Q25)

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Q1. The most common hazard in highwall mining is:
A. Roof fall
B. Slope failure
C. Gas explosion
D. Flooding
E. Conveyor failure
Answer: B.
Solution: Slope or wall collapse is the leading hazard due to strata instability.

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Q2. SSR stands for:
A. Safety System Record
B. Slope Stability Report
C. Seismic Safety Register
D. Site Stability Record
E. Structural Strength Report
Answer: B.
Solution: SSR is prepared by a geotechnical engineer to assess slope stability.

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Q3. Minimum setback distance from highwall toe should be:
A. ½ × bench height
B. Equal to bench height
C. Twice the bench height
D. 10 m minimum
E. As per local decision
Answer: B.
Solution: Setback must not be less than the height of the highwall.

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Q4. Slope stability factor of safety should not be below:
A. 1.2
B. 1.3
C. 1.5
D. 1.0
E. 2.0
Answer: C.
Solution: DGMS requires a minimum FoS of 1.5 for stable slopes.

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Q5. DGMS Circular 06 of 2018 deals with:
A. Lighting in mines
B. Remote control and slope monitoring
C. Explosives management
D. PPE requirement
E. Transport safety
Answer: B.
Solution: It defines automation and slope monitoring protocols for highwall mining.

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Q6. Radar displacement alarm limit is:
A. 2 mm/hr
B. 5 mm/hr
C. 10 mm/hr
D. 20 mm/hr
E. 50 mm/hr
Answer: C.
Solution: Above 10 mm/hr, automatic alarm and machine halt are required.

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Q7. SSR must include which of the following?
A. Rainfall data
B. Geology details
C. FoS values
D. Monitoring records
E. All of the above
Answer: E.
Solution: SSR integrates all slope, rainfall, and FoS parameters.

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Q8. Daily highwall inspections are carried out by:
A. Surveyor
B. Geologist
C. Manager or authorized official
D. Safety officer only
E. Foreman
Answer: C.
Solution: The mine manager is responsible for daily inspection.

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Q9. DGMS mandates radar installation for:
A. Deep underground mines
B. Surface workshops
C. Highwall benches
D. Explosive magazines
E. Conveyor areas
Answer: C.
Solution: Every active highwall bench must have slope radar.

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Q10. Water seepage near highwall toe should be:
A. Ignored
B. Pumped immediately
C. Allowed to accumulate
D. Used for dust control
E. Measured only weekly
Answer: B.
Solution: Seepage should be drained or pumped to maintain slope integrity.

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Q11. The SSR must be approved by:
A. Mine Manager
B. DGMS Regional Inspector
C. DGMS (Tech.)
D. Owner only
E. Geologist
Answer: B.
Solution: The Regional Inspector reviews and approves SSR submissions.

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Q12. The minimum inspection frequency by DGMS is:
A. Monthly
B. Quarterly
C. Half-yearly
D. Weekly
E. Annual
Answer: B.
Solution: DGMS conducts quarterly safety and SSR compliance checks.

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Q13. Highwall slope radar calibration is recommended:
A. Daily
B. Monthly
C. Quarterly
D. Yearly
E. None
Answer: C.
Solution: Calibration every quarter ensures reliability and accuracy.

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Q14. Real-time radar monitoring transmits data to:
A. Local server
B. DGMS portal
C. Manager’s office
D. OEM control center
E. All of the above
Answer: E.
Solution: Data is sent simultaneously to multiple destinations for safety.

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Q15. The DGMS circular requiring real-time data sharing is:
A. 01/2018
B. 04/2017
C. 01/2020
D. 06/2018
E. 05/2019
Answer: C.
Solution: Circular 01/2020 enforces real-time monitoring and cloud sharing.

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Q16. Highwall failure probability increases with:
A. Steeper slope angle
B. Lesser rainfall
C. High FoS
D. Proper drainage
E. Dry weather
Answer: A.
Solution: Steep slopes (>70°) have higher risk of failure.

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Q17. Drainage channels must have a minimum gradient of:
A. 0.2%
B. 1%
C. 2%
D. 3%
E. 5%
Answer: C.
Solution: Minimum 2% slope ensures continuous water runoff.

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Q18. SSR should be updated:
A. Yearly
B. After every monsoon
C. Every 6 months
D. Quarterly
E. Every 3 years
Answer: B.
Solution: Post-monsoon SSR review is mandatory for all highwall mines.

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Q19. DGMS-approved radar sensors are typically:
A. Thermal
B. Laser
C. Ground-based InSAR
D. Optical
E. Microwave
Answer: C.
Solution: Ground-based InSAR systems measure slope deformation precisely.

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Q20. During slope instability, mining operations:
A. Continue normally
B. Should be suspended
C. Shifted to adjacent bench
D. Doubled output
E. Wait for next inspection
Answer: B.
Solution: Immediate suspension until slope stability is restored.

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Q21. Safety barricades must be built at least:
A. 0.5 m high
B. 1 m high
C. 1.5 m high
D. 2 m high
E. As convenient
Answer: C.
Solution: Minimum height of 1.5 m prevents accidental vehicle slips.

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Q22. SSR rainfall correction factor ensures:
A. Better output
B. Safety of spoil dump
C. Slope stability evaluation
D. Machine performance
E. Weather prediction
Answer: C.
Solution: Rainfall intensity alters slope shear strength, requiring correction.

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Q23. Data backup of slope monitoring logs should be retained for:
A. 3 months
B. 6 months
C. 1 year
D. 3 years
E. 5 years
Answer: D.
Solution: DGMS mandates minimum 3-year record retention.

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Q24. Parapet walls along haul roads are provided for:
A. Drainage
B. Edge protection
C. Dust control
D. Road widening
E. Decoration
Answer: B.
Solution: Prevents accidental overrun of heavy machinery.

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Q25. During slope radar alarm, operator must:
A. Reduce speed
B. Inform DGMS only
C. Stop operations immediately
D. Ignore warning
E. Restart system
Answer: C.
Solution: Immediate stoppage avoids disaster due to wall collapse.

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                    ✅ Conclusion 

Highwall mining operations demand strict compliance with DGMS safety circulars and slope monitoring standards.
By maintaining SSR records, radar monitoring, drainage systems, and setback distances, mines can ensure safe and efficient operations while meeting DGMS inspection requirements.

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