Pipes have been inserted up to 52 metres through the rubble at Silkyara tunnel, Uttarakhand Chief Minister Pushkar Singh Dhami said on Tuesday as efforts to rescue the 41 workers trapped there continued for the 17th day.
The breakthrough point is 57 metres, he told reporters in Silkyara.
Twelve rat-hole mining experts are involved in the horizontal excavation 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 since Monday.
This drilling was earlier carried out by a huge auger machine that got stuck in the rubble on Friday at around 47 metres.
"We have just crossed 50 metres," L&T team leader Chris Cooper told PTI early on Tuesday. It raised hopes of an early evacuation as rescuers have to go only up to 10 metres to make a breakthrough.
However, the speed of the operation depends on whether or not the rescuers encounter any hurdle in the course of excavation which has often been hampered by something or the other.
Later, Chief Minister Dhami, while visiting the rescue operation site, said, "Pipe has gone in up to 52 metres. Earlier it was at 51 metres. It was pushed one metre further in my presence. It will be pushed two metres more to 54 metres after which one more pipe will be laid." When asked whether there were hurdles on the way, he said steel and iron girders were not being encountered. "Stones are coming in the way but they are being broken using cutters," the chief minister said.
A skilled team of workers is removing muck by hand using the rat-hole mining technique while 800-mm diameter pipes are being inserted by a auger machine through the rubble.
Praveen Yadav, who is involved in cutting and removing the hurdles from the debris, said 51 metres have been drilled.
A worker from the Trenchless company, which is pushing the pipes with the auger machine, said if no hurdles are faced, some good news could be expected by this evening.
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.
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. Rajput Rai, a rat-hole drilling expert, said one man will do the drilling, another collects the rubble with his hands and the third places it on a trolley to be pulled out.