Explained: What Is Rat-Hole Mining — Vital Technique Used In Uttarkashi Tunnel Rescue Operation

After relentless efforts to rescue 41 workers trapped inside the collapsed Silkyara tunnel in Uttarakhand, a team of "rat-hole miners" has taken on the task of drilling through the debris.

The collapsed portion of the under-construction tunnel on the Char Dham route presented a challenging situation for the rescuers.

Shift In Rescue Strategy

After more than two weeks of a multi-agency rescue mission, officials have shifted their focus to alternatives.

The first option involves manual drilling through the remaining stretch of rubble, while the second, more likely option, is drilling down 86 metres from above.

The horizontal drilling using a large auger machine faced obstacles when the machine got stuck in the rubble, leading to the consideration of the alternative drilling approach from above.

A group of twelve rat-hole mining experts has been mobilised for manual drilling and excavation. Their focus is on the last 10- or 12-metre stretch of debris separating the rescuers from the trapped workers.

The Uttarakhand government's nodal officer, Neeraj Khairwal, clarified that the individuals brought to the site were experts in the rat-hole mining technique, emphasising the importance of their skills in this critical situation, reports Indian Express.

Rajput Rai, a rat-hole drilling expert, explained that teams would be divided for specific tasks, including drilling, collecting rubble, and transporting it out using a trolley.

The rat-hole method, a technique involving narrow burrows or tunnels, is seen as a beacon of hope as the rescuers are just 5 metres away from reaching the trapped individuals after 17 days.

What Is Rat-Hole Mining?

Rat-hole mining, a prevalent coal extraction method in Meghalaya, involves the retrieval of coal from narrow, horizontal seams.

The term "rat hole" signifies the small pits dug into the ground, typically sized just enough for a single person to descend and extract coal.

After the pits are excavated, miners descend using ropes or bamboo ladders to access the coal seams.

The rat-hole mining encompasses two primary types.

In the side-cutting procedure, narrow tunnels are dug on the hill slopes, and workers venture inside until they locate the thin coal seam, which is often less than 2 metres in most cases in the hills of Meghalaya.

The alternative method, known as box-cutting, involves creating a rectangular opening ranging from 10 to 100 square metres. Through this opening, a vertical pit is excavated, reaching depths of 100 to 400 feet.

Once the coal seam is identified, rat-hole-sized tunnels are horizontally dug to facilitate coal extraction by workers.

Given the thin coal seam in Meghalaya, alternative methods are deemed economically impractical. The prospect of extracting rocks from the rugged terrain and installing support pillars inside the mines to avert collapses presents a substantially higher cost.

Consequently, the locally developed technique of rat-hole mining has become the most prevalent and economically viable approach in Meghalaya.

Why Is It banned?

Rat-hole mining lacks regulation, and safety measures, and raises environmental concerns. The miners, often working in dangerous conditions without proper safety provisions, use tools like pickaxes, shovels, and baskets.

Rat-hole mining has been associated with tragic incidents, including the death of 15 miners trapped in a flooded coal mine in Meghalaya in 2019.

The practice has faced criticism for dangerous working conditions, accidents, and environmental damage.

The impact of rat-hole mining is acutely felt in the water sources of numerous rivers, particularly in the Jaintia Hills district. Alarming reports indicate a shift towards acidity in these water bodies.

The environmental toll extends beyond water contamination to include significant pollution from the roadside dumping of coal.

While the National Green Tribunal banned rat-hole mining in 2014, the Supreme Court overturned the ban in 2019, allowing scientific mining methods in Meghalaya.