As multiple agencies raced against time to rescue the 41 workers who were trapped inside Uttarakhand's Silkyara tunnel, a team from Nagpur-based Western Coal Fields monitored the level of carbon dioxide there to ensure that the workers did not gasp for breath.
The workers were rescued from the collapsed tunnel in Uttarkashi after a gruelling 16-day operation that culminated on Tuesday evening.
Three experts from Western Coal Fields, a subsidiary of Coal India Limited, camped at the Silkyara tunnel site from November 20.
They were part of the core committee involved in discussions and key decisions, said general manager (rescue services) Dinesh Bisen, a member of the team.
Deputy manager (rescue services) M Vishnu and CMPDI director AK Rana were also part of the team, he said.
A portion of the under-construction on Uttarakhand's Char Dham route collapsed on November 12, blocking the exit of the workers who were inside the tunnel and triggering a massive rescue operation.
Bisen told PTI that equipment like American-made auger boring machine, cranes and lifts were used inside the tunnel and their operation produced carbon dioxide.
He said their team's role was to monitor the level of carbon dioxide and ensure that it did not increase inside the tunnel and cause any breathing difficulties for the workers.
Whenever CO2 level went up, machines were stopped and efforts were initiated to improve ventilation inside the tunnel, he said.
Bisen said the mission was particularly challenging as it was different from a similar operation inside a mine. In the case of a mine, the width of the “gallery” (passageway) is 4.5 metres to 5 metres, but the Silkyara tunnel is 16 metres wide, he said.
Besides, new problems, including the breaking down of the auger boring machine, were encountered every now and then.
Bisen said their WCL rescue team has won several national and international awards for its role in rescue missions, but this job was special.
“It was a once-in-a-lifetime opportunity to work in such a situation. We thank CIL for giving us this opportunity. The entire world was watching and we were able to rescue our brothers safely. There is no other big achievement in life than this,” he said.
When those executing the rescue operation started vertical drilling to reach the trapped workers after the auger machine got stuck, Bisen said they provided the design of a rescue capsule and helped in its fabrication.
“Had the evacuation happened through that capsule, then we, along with NDRF, would have been responsible for lifting them (the trapped workers) safely,” he added.