In Uttarakhand, experts have turned to ‘rat-hole’ mining as part of the efforts to rescue 41 workers trapped inside the collapsed Silkyara tunnel. As of Tuesday morning (Nov 28), a section of five to six meters was yet to be manually drilled, while simultaneous vertical drilling was underway.
By Tuesday morning, the drilling from above the tunnel had reached a depth of 36 meters, out of the required 86 meters. A team of 12 rat-hole mining experts is actively engaged in the rescue operations. It’s essential to understand what rat-hole mining entails and the associated risks.
Rat-hole mining involves the excavation of narrow pits into the ground, commonly employed in the northeastern states of India for extracting coal from tight, horizontal seams. These ‘rat holes’ are sufficiently large for one person to access and extract coal. In the current context, experts in Uttarakhand are utilizing rat-hole mining to manually remove rubble from the collapsed tunnel, with the flexibility to dig these holes both vertically and horizontally.
Rat-hole mining is broadly categorized into two procedures: the side-cutting method and box-cutting. In the side-cutting procedure, narrow tunnels are dug on hill slopes, and workers enter until they locate the thin coal seam. Alternatively, box-cutting involves initially digging a vertical rectangular pit, typically 100 to 400 feet deep, and subsequently creating horizontal passages to better reach the coal seam.
However, rat-hole mining comes with significant risks as it is largely unregulated, and miners often operate without proper ventilation, safety equipment, or structural support. This lack of oversight raises concerns about the safety of workers engaged in such mining practices.
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