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Water Hazards in Underground & Opencast Mines – DGMS Notes

πŸ’§Introduction
Water is one of the most dangerous hazards in mining. Sudden inrush of water from old workings, surface sources, aquifers, or heavy rains can cause catastrophic mine inundations. Many of India’s worst mine disasters (e.g., Chasnala 1975) were caused by uncontrolled water hazards. The DGMS (Directorate General of Mines Safety) prescribes strict provisions under the Mines Act, Coal Mines Regulations 2017, Metalliferous Mines Regulations 1961, and DGMS circulars to prevent and control water hazards. Understanding these rules is critical for DGMS exams and for safe mine management.
⚠️ Types of Water Hazards
  • Surface Water Inflow: Heavy rains, rivers, or surface reservoirs entering through cracks, shafts, or opencast benches.
  • Old Workings: Accidental connection with water-logged abandoned workings.
  • Aquifers / Water-bearing Strata: Sudden inflow during drivage of headings or shaft sinking.
  • Overburden Dumps / Seepage: Water from OB benches or seepage through highwalls in opencast mines.
  • Seasonal Hazards: Monsoon flooding in opencast pits.
Exam Tip: DGMS often asks: β€œWhat is the most dangerous source of water hazard in underground coal mines?” β†’ Answer: Old water-logged workings.
πŸ’‘ Prevention & Drainage Systems
  1. Survey & Plan Control
    • Accurate plans showing adjacent old workings (survey within 15 m accuracy).
    • Protective barrier thickness (Coal Mines Regulation 127).
  2. Shaft Sinking & Drivage Precautions
    • Fore-poling, borehole drilling, and cover drilling ahead of face.
    • Adequate pumping arrangements.
  3. Pumping & Drainage
    • Main pumps with standby units (CMR 2017 Reg. 126).
    • Sump capacity β‰₯ 4 hours maximum inflow.
    • Regular inspection of pump houses.
  4. Opencast Mines
    • Garland drains, sump pumps, dewatering wells.
    • Bench sloping and catch drains.
    • Storm water diversion channels.
  5. Monitoring & Emergency Measures
    • Water gauges, borehole monitoring.
    • TARP (Trigger Action Response Plan) for sudden inflows.
    • Refuge chambers and emergency escapeways.
πŸ“‘ DGMS Case Studies (H3)
  • Chasnala Disaster (1975): 375 miners killed due to inrush from old workings.
  • Kundra Pahar (2001): Fatal inundation in coal mine due to insufficient barrier.
  • Opencast flooding (Jharkhand, 2019): Heavy monsoon inflow overwhelmed pit drainage.
Lesson: Every water disaster highlights the importance of survey, protective barriers, pumping, and drainage systems.
πŸ“ Quick One-Liners
  • Old water-logged workings β†’ biggest water hazard.
  • Survey accuracy: 15 m (CMR 127).
  • Protective barrier thickness mandatory between mine boundaries.
  • Pumping capacity: Standby pump + 4 hours sump capacity.
  • Garland drain + sump system = standard in opencast mines.
  • TARP = Trigger Action Response Plan for water inflows.
  • CMR 126 β†’ drainage and pumping arrangements.
  • DGMS circulars stress survey, boreholes, and risk analysis.
✍️ Descriptive Model Answer
Q: What are the statutory provisions and preventive measures for water hazards in coal mines?
Answer:  Water hazards in mines are regulated under CMR 2017 (Regs. 126–128), which mandate accurate surveys, barrier thickness, pumping arrangements, and preventive boreholes. The main measures are:
  • Surveys: Plans must show water bodies and old workings with ≀15 m accuracy.
  • Barriers: Protective coal barrier thickness left between adjacent mines.
  • Pumping: Main and standby pumps, sumps for 4 hours inflow, regular inspections.
  • Boreholes: Cover drilling to detect water before drivage.
  • Drainage: Garland drains, diversion channels, sump pumps in opencast mines.
  • Emergency: TARP, escape routes, and training.
Conclusion: Strict adherence to CMR 2017 and DGMS guidelines is vital to prevent disasters like Chasnala.
🎯 20 MCQs – Water Hazards (DGMS Exam Practice)
Q15.1 The most dangerous source of water hazard in underground coal mines is:
 A. Aquifer seepage
B. Old water-logged workings
C. Rainwater inflow
D. Pump failure
E. High humidity
Answer: B.
Solution: Inundations mainly occur from old flooded workings.
Q15.2 Minimum accuracy of survey for detecting old water-logged workings is:
 A. 30 m
B. 20 m
C. 15 m
D. 10 m
E. 5 m
Answer: C.
Solution: CMR 2017 requires ≀15 m accuracy.
Q15.3 Sump capacity must be at least:
 A. 2 hours inflow
B. 3 hours inflow
C. 4 hours inflow
D. 6 hours inflow
E. 8 hours inflow
Answer: C.
Solution: Regulation 126 requires 4 hours inflow capacity.
Q15.4 Protective barrier thickness between adjacent mines is required under:
 A. Reg. 124
B. Reg. 125
C. Reg. 127
D. Reg. 129
E. Reg. 131
Answer: C.
Solution: Reg. 127 covers barrier thickness.
Q15.5 DGMS mandates standby pumps because:
 A. Save electricity
B. Handle peak inflow
C. Ensure pumping during breakdown
D. Reduce manpower
E. None
Answer: C.
Solution: Standby ensures safety if main pump fails.
Q15.6 In opencast mines, primary drainage system is:
 A. Forepoling
B. Garland drains and sumps
C. Shaft pumps
D. Borehole drilling
E. None
Answer: B.
Solution: Standard OC drainage uses garland drains + sump pumps.
Q15.7 The Chasnala Disaster (1975) was caused by:
 A. Fire
B. Gas explosion
C. Inrush of water from old workings
D. Roof fall
E. Slope failure
Answer: C.
Solution: Over 375 miners died due to inundation.
Q15.8 Pumping arrangements are covered under:
 A. CMR 121
B. CMR 124
C. CMR 126
D. CMR 127
E. CMR 131
Answer: C.
Solution: Regulation 126 = drainage & pumping.
Q15.9 Which system detects water before drivage?
 A. Borehole drilling
B. Gas detectors
C. Fire hydrant system
D. Air shaft
E. Roof bolting
Answer: A.
Solution: Cover boreholes detect water hazards ahead.
Q15.10 TARP stands for:
 A. Technical Action Recovery Plan
B. Trigger Action Response Plan
C. Training Action Relief Program
D. Technical Accident Response Procedure
E. None
Answer: B.
Solution: TARP = emergency water hazard management system.
Q15.16 Water danger plan in a mine is prepared by:
 A. Overman
B. Mine Manager
C. Surveyor
D. Mining Engineer in training
E. Shotfirer
Answer: B.
Solution: The Manager is legally responsible for preparing a water danger plan under CMR/MMR.
Q15.17 Minimum borehole cover drilling distance ahead of face for detecting water hazards is:
 A. 10 m
B. 15 m
C. 20 m
D. 30 m
E. 50 m
Answer: C.
Solution: Standard DGMS guideline: at least 20 m cover drilling ahead of the drivage.
Q15.18 Water danger plan is required to be updated:
 A. Every 3 months
B. Every 6 months
C. Every year
D. Every 2 years
E. Once in mine life
Answer: C.
Solution: Plans must be updated annually to reflect changes in water hazard zones.
Q15.19 Which regulation requires boreholes to be drilled before approaching suspected water-logged areas?
 A. CMR 124
B. CMR 125
C. CMR 128
D. CMR 130
E. CMR 132
Answer: C.
Solution: Regulation 128 mandates boreholes before advancing near suspected water bodies.
Q15.20 Main pumps in underground mines must have:
 A. No standby arrangement
B. One standby pump of equal capacity
C. Smaller pump for emergencies
D. Portable hand pump only
E. None
Answer: B.
Solution: At least one standby pump of equal capacity is compulsory (CMR 126).
Q15.21 In opencast mines, storm water diversion channels are constructed:
 A. Only after monsoon
B. Around the pit to prevent rain inflow
C. Inside haul roads
D. In workshop area only
E. To collect drinking water
Answer: B.
Solution: Diversion channels prevent storm water from entering pits.
Q15.22 Which DGMS circular emphasizes water danger plans and borehole drilling?
 A. Tech Circular 2 of 2010
B. Tech Circular 1 of 1999
C. Tech Circular 5 of 2012
D. Legis Circular 3 of 2020
E. General Circular 1 of 2023
Answer: B.
Solution: DGMS Tech Circular 1 of 1999 highlights survey, boreholes, and plans for water hazard prevention.
Q15.23 Which Act empowers DGMS to enforce water hazard safety?
 A. Mines Act, 1952
B. Factories Act, 1948
C. Petroleum Act
D. Boilers Act
E. Electricity Act, 2003
Answer: A.
Solution: Mines Act 1952 empowers DGMS to enforce safety provisions in mining, including water hazards.
Q15.24 Inundation from surface water in opencast mines is controlled by:
 A. Boreholes
B. Garland drains and pumping systems
C. Increasing gradient of haul roads
D. Using OB dumps
E. Stopping blasting
Answer: B.
Solution: Garland drains and pumps are primary defenses against surface water flooding in opencast mines.
Q15.25 Chasnala mine disaster (1975) highlighted the need for:
 A. Better roof support
B. Larger winding engines
C. Stronger ventilation fans
D. Accurate water danger plans & barriers
E. More explosives storage
Answer: D.
Solution: The tragedy emphasized importance of barrier thickness and water danger planning.

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