The first visuals of manual drilling inside the Silkyara tunnel in Uttarakhand’s Uttarkashi to rescue the 41 trapped workers were released by news agency ANI on Tuesday morning. While the manual drilling is underway, the auger machine is being used for pushing the pipe.

So far, about two metres of manual drilling has been completed, ANI reported. Rat-hole mining experts called in to help rescue the 41 workers began manual drilling on Monday through the rubble.

Simultaneously, vertical drilling from above the tunnel has reached a depth of 36 metres out of the 86 metres needed.

Twelve rat-hole mining experts are involved in manual drilling and excavation horizontally through the last 10- or 12-metre stretch of debris of the collapsed portion of the under-construction tunnel on Uttarakhand’s Char Dham route.

This drilling was earlier being carried out by a huge auger machine that got stuck in the rubble on Friday, forcing officials to focus on an alternative option — drilling down from above the tunnel. About 40 per cent of the 86-metre vertical drilling required is now done.

For the horizontal through-the-rubble option, officials decided that the final stretch would be handled through a manual approach in which individual workers will go into the escape passage with drills, as well as gas-cutters to tackle obstacles like iron girders.

By Monday evening, the last bit of the stuck auger had been cut out piece by piece and a steel pipe inserted further into the partially complete escape passage.

In Delhi, National Disaster Management Authority (NDMA) member Lt Gen (retd) Syed Ata Hasnain said vertical drilling, which began Sunday, has already reached a depth of 36 metres.

Rescuers hope to pull out workers through this one-metre-wide shaft when it breaks through the top of the tunnel below, hopefully by Thursday. Another eight-inch wide shaft being drilled from a nearby point has reached about 75 metres down.

This probe, which is also expected to act as a supply line for the trapped workers, has indicated that there were no serious geological obstacles for the main shaft up to this point, the NDMA member and officials at Silkyara said.

The vertical drilling, however, encountered some water underground and “dewatering” was carried out, officials said. But it didn’t seriously affect the operation.

Two teams of seven and five men who are experts in the technique of rat-hole mining were called in by two private companies involved in the rescue operation.

Rat-hole mining is a controversial and hazardous procedure in which miners in small groups go down narrow burrows to excavate small quantities of coal.

Uttarakhand government’s nodal officer Neeraj Khairwal made it clear that the men brought to the site were not rat-hole miners but people who are experts in the technique, news agency PTI reported.

They are likely to be divided into teams of two or three. Each team will go into the steel chute laid into the escape passage for brief periods.