With reference to 'Rat-hole mining' as practiced in parts of Northeast India, identify the correct statements.

Question

With reference to 'Rat-hole mining' as practiced in parts of Northeast India, identify the correct statements.

I. It is a process of digging narrow horizontal tunnels into the hill slopes by extraction workers.

II. The National Green Tribunal has banned this practice.

III. Acid Mine Drainage (AMD) caused by this practice is characterized by high pH levels, making the water highly alkaline.

1. A. I and III only
2. B. II only
3. C. I and II only (Correct answer)
4. D. All of the above

Correct Answer

Option C — I and II only

Detailed Solution & Explanation

The correct answer is I and II only.

Key Points

• Statement I is correct. Rat-hole mining is a primitive method of coal extraction in which narrow horizontal tunnels — typically only 3–4 feet high, just wide enough for one person to crawl through — are dug into hill slopes to reach thin coal seams. It is practised mainly in Meghalaya, especially in the Jaintia Hills.
• Statement II is correct. The National Green Tribunal (NGT) banned rat-hole mining in April 2014, citing the deaths of workers, the absence of safety measures and severe water pollution. The Supreme Court upheld the ban in 2019.
• Statement III is incorrect. Acid Mine Drainage (AMD) is characterised by low pH, making water strongly acidic — not alkaline. When pyrite (FeS₂) in exposed coal seams reacts with water and oxygen, it produces sulphuric acid, driving the pH of nearby rivers down to 2–4.

Additional Information

• Effects of rat-hole mining:
  • Rivers such as the Lukha and Myntdu in Meghalaya turned blue-green and became devoid of fish because of acidification.
  • Frequent fatal accidents — the Ksan mine tragedy (December 2018) in East Jaintia Hills trapped 15 miners.
  • Loss of forest cover, soil erosion and land subsidence.
• Acid Mine Drainage in brief:
  • $2FeS_2 + 7O_2 + 2H_2O \rightarrow 2Fe^{2+} + 4SO_4^{2-} + 4H^+$
  • The released $H^+$ ions lower the pH; the dissolved metals then become mobile and toxic.
• Exam pointer: any statement describing acid drainage as "alkaline" or "high pH" is self-contradictory — the word *acid* settles it.