The operation to rescue the workers trapped in Uttarakhand's Silkyara tunnel has been going on for 17 days. The delay in bringing out the workers was partly due to the obstructions faced by the drilling machines while clearing the debris.
Auger and drilling machines kept hitting metal obstructions in the debris, stalling the rescue work.
This led to manual intervention with rescue workers entering the the narrow pipes pushed through the rescue holes to cut the metal structures using gas cutters.
According to the Indian Express, on the 12th day of the rescue operation, the teams faced a similar situation.
Praveen Yadav, an underground tunnelling expert for Trenchless Engineering, told Indian Express that several people tried to enter the narrow pipes but could not in the absence of a proper oxygen supply.
He volunteered to go in but his boss asked him to wait for the National Disaster Response Force personnel to try.
Yadav told the Indian Express that NDRF jawans were to big and the rescue pipes too small so he ultimately went in with two other people.
Yadav said he took a gas cutter, two bottles of water and crawled into the pipes on his knees and elbows.
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He said that sometimes the work requires him to go inside those pipes two or three times a day.
Yadav and his aides found the metal girders and cut them using gas cutters. They then removed the cut pieces.
He said that the process generated a lot of heat and they faced the risk of sustaining burn injuries.