Rescuers have started manual horizontal digging, in addition to the ongoing vertical drilling, at the Silkyara tunnel in Uttarkashi, the National Disaster Management Authority (NDMA) said on Monday.
Vertical drilling by SJVNL was progressing fast as rescuers had drilled nearly 36 m out of 86 m. The machine encountered boulders in its way and faced watering during the process. “The dewatering was soon done,” a source in the know said. Pipes of 1.2 m in diameter will have to be laid vertically through the top of the tunnel, on which work began on Sunday as a second option to reach the 41 stranded workers.
NDMA member Syed Ata Hasnain said rat-hole miners would engage in manual digging. “Rat-mining is a method to remove coal deposits through narrow passages. We hope this method may deliver good results. Rat-miners have to dig nearly 12 m for the evacuation of trapped workers,” another source at the tunnel collapse site said, adding that other options are also available to carry out manual drilling.
“Broken parts of the auger machine have been removed from the rubble with the help of a plasma cutter flown in from Hyderabad,” the source said. The head of the machine got stuck during drilling and the process to pull out this part was underway till Monday afternoon, he added.
Vertical and manual horizontal drilling are the two methods on which rescue efforts are now focused. Work on other options, such as horizontal drilling from the Barkot end of the tunnel, is also underway.
Manual drilling was resorted to as the auger drill – a corkscrew-like device with a rotary blade at the front end, which drilled up to 47 m – was busted as it hit several hurdles on the way and got entangled in a girder in the debris.
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