What is rat-hole mining? A technique being used to help rescue Uttarakhand workers

Experts in Uttarakhand resorted to ‘rat-hole’ mining to help rescue 41 workers trapped inside the collapsed Silkyara tunnel. All the workers were rescued and rat-hole mining was used to clear the last few metres in the rescue operations. By Tuesday morning, drilling from above the tunnel had reached a depth of 36 metres out of the 86 metres needed.

A total of 12 rat-hole mining experts were involved in the rescue operations. Let’s understand what is rat-hole mining, and what are the risks associated with it?

What is rat-hole mining?

The term ‘rat-hole’ refers to a narrow pit dug into the ground. Generally, this technique is used in Northeastern states of India to extract coal from narrow, horizontal seams.

These ‘rat holes’ are large enough to allow one person to move in and extract coal.

In a similar manner, experts in Uttarakhand are digging narrow ‘rat holes’ to manually extract the rubble from pipe. These rat holes can be dug both vertically and horizontally. 

Rat-hole mining is broadly classified into two categories: Side-cutting procedure and box-cutting.

“In the side-cutting procedure, narrow tunnels are dug on the hill slopes and workers go inside until they find the coal seam. The coal seam in hills of Meghalaya is very thin, less than 2 m in most cases,” OP Singh, professor of environmental studies at North Eastern Hill University (NEHU) in Shillong, was quoted as saying by The Indian Express.

Box-cutting involves digging a vertical rectangular pit first, 100 to 400 feet deep, and then digging horizontally as and when required to better reach the coal seam.

Risks associated with rat-hole mining

Rat-hole mining is largely unregulated and miners have to work without proper ventilation, safety gears and any structural support.

Authorities around the world and India have attempted to regulate this method, or ban it altogether; but the practice still persists due to economic factors and the absence of viable alternatives.

(With inputs from agencies)