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After repeated setbacks, vertical drilling operations commenced from atop the hill above the collapsed section of the tunnel yesterday. By the end of the day, rescuers had successfully penetrated nearly 20 metres into the mountainside.
National Highways and Infrastructure Development Corporation Limited (NHIDCL) managing director Mahmood Ahmed said the drilling process will be successfully concluded by Thursday, provided no unforeseen obstacles arise.
As the vertical boring operation progresses, workers carefully insert 700-mm wide pipes to create a secure passageway for those trapped inside the tunnel. Simultaneously, a 200-mm probe is also being pushed in. It has reached the 70-metre mark.
The heavy auger drill, brought in from the US to break through nearly 60 metres of debris, was damaged on Friday and is now being pulled out. The last 10-15 metres will now have to be broken with hand-held power tools, a significantly more time-consuming process. Workers are entering the unfinished escape passage, equipped with a steel chute, to dismantle the jammed auger blades and shaft.
Prime Minister Narendra Modi's Principal Secretary PK Mishra reached the tunnel today to review the rescue operations. He was accompanied by Chief Secretary Sukhbir Singh Sandhu. Some senior officials of the Centre will also be present.
Rescuers will now adopt a new approach: manual drilling to eliminate the remaining 10 to 12 metres of debris. A worker will enter the steel chute laid out and operate a drill while another will use a pulley system to remove the resulting debris. Rescue officials said other extraction plans are also being considered.
From Tuesday, a horizontal 180-metre alternate escape tunnel will be excavated into the hillside by rescue workers, an endeavor that could take 12-14 days to complete. Drilling is advancing at the Barkot-end of the tunnel, with about 10 metres out of 483 metres completed. This strategy could take up to 40 days of drilling, officials estimated.
The trapped workers are located within a 2-kilometre segment of the tunnel that remains structurally stable. They are receiving food, medical supplies, and other items through a six-inch wide pipe. A communication network has also been set up so that the trapped workers can talk to their families.
Forty-one ambulances remain on standby at the tunnel's entrance, ready to whisk the workers away to the Chinyalisaur Community Health Centre. A designated ward has also been set up with 41 oxygen-equipped beds, prepared to provide each worker with prompt medical care.
Situated about 30 km from Uttarkashi and a seven-hour drive from Dehradun, the Silkyara tunnel is an integral part of the central government's Char Dham all-weather road project.
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