The rescue operation to extract 41 labourers from an under-construction tunnel in Uttarakhand’s Uttarkashi that collapsed on 12th November entered its seventh day on Saturday (18th November). 165 personnel-strong rescue team from multiple agencies is working round-the-clock and all necessary measures have been put in place including roping in assistance from tunnel rescue experts from Thailand and Norway.
However, the rescue efforts have encountered various challenges, with intermittent pauses attributed to factors such as fumes produced by the diesel-driven machinery in confined spaces, vibrations during drilling in the tunnel, and technical malfunctions in the drilling equipment.
Notably, on Friday (17th November) afternoon, the rescue operation was briefly halted for nearly an hour. The drilling work was halted after a loud cracking sound was heard in the tunnel at around 2:45 pm. The precautionary halt was taken as debris began once again falling toward the drilling machine while the rescue team was inserting the fifth tube into the tunnel. Soon, the rescue workers inside the tunnel were quickly evacuated to ensure their safety.
The current rescue plan involves inserting six-meter sections of steel pipes one after the other as the machine drills through the debris. Each pipe has a diameter of 800 or 900 mm providing enough space for trapped labourers to squeeze out once the rescue team drills through the 60-meter debris and the pipes are inserted.
“The machine is not able to push further as the machine is getting lifted and its bearings are getting damaged. Now they are anchoring the machine to a platform,” NHIDCL, which is building the tunnel said in a statement.
Additionally, on Friday, the rescue operation also faltered as the second drilling machine also suffered damage, forcing authorities to slow down operations. Moreover, they were also forced to call in another auger machine and prepare a contingency plan.
Amid reports that the American auger machine, employed for drilling, encountered a technical fault, the construction company refuted these claims. It asserted that another American auger machine weighing approximately 25 tonnes was being brought in from Indore as a mere ‘backup’. As per media reports, it was slated to arrive at the rescue site today morning.
Further, according to the National Highways and Infrastructure Development Corporation Limited (NHIDCL) director Anshu Manish Khalkho, the operation occasionally pauses due to factors such as fumes generated by the diesel-driven machine in confined spaces and vibrations induced in the tunnel during drilling.
Another reason for the delay in the rescue operation is the complexity of achieving precise alignment of pipes and welding them before pushing through the debris has been taking time, the company director noted.
Khalkho explained, “The pipes, each 6 metres in length, are aligned on the machine and pushed forward, with the auger drilling through debris and pushing muck backward. While this part of the process is relatively quick, the complexity arises during the alignment and welding of the pipes. The meticulous approach is intentional to prevent any misalignment, even for a centimetre.”
Earlier while explaining the challenges faced by the rescue team, Khalkho said, “The nature of the rocks here is quite fragile, posing a significant challenge to the operation.”
An additional hurdle in the rescue operation is that they are forced to use diesel-powered auger machines within a confined space which pose breathing difficulties and should not be used in closed spaces.
Khalkho added, “Diesel machines should ideally not operate in such confined spaces as the vibrations and need for continuous ventilation pose risks. But there is no other option, which is why we must run at optimal speed without rushing.”
Plan C involving the Indian Army
The repeated halts and operational difficulties coupled with machines developing technical slags have forced the rescue teams to develop a contingency plan. As horizontal drilling is facing challenges, the rescue team will now start separately drilling from the upper section of the tunnel. Uttarkashi DFO DP Baluni said that a spot right above the tunnel has been identified to start the vertical drilling. He said that a hole will be drilled from the top of the hill to reach the section of the tunnel where the workers are trapped. The depth of the whole would be approximately 300-350 feet.
#WATCH | Uttarkashi, Uttarakhand: On the rescue operation at the under-construction tunnel collapse, Uttarkashi DFO DP Baluni says, "… We were trying to reach them horizontally, now we will also try vertically… A spot right above the tunnel has been identified and marked. A… pic.twitter.com/0f4wlqVRd1
— ANI (@ANI) November 18, 2023
Earlier an official involved in the rescue operation said that a team of geological experts was exploring a “plan C” and trying to identify suitable locations for creating a “parallel vertical tunnel followed by a horizontal one and vice versa”.
The official had said, “Initially, we did not conduct this survey as we believed we could navigate through the 60 metres of debris. However, based on a previous survey, we identified that a minimum drill depth of 103 metres will be required for this plan C. Implementing a 103-metre vertical drill poses risks as it may lead to additional debris falling. Nevertheless, if the current plan proves ineffective, we may consider exploring this alternative option.”
#WATCH | Uttarkashi tunnel rescue | "We have been given the work to build a trek so that we can do vertical drilling…We have to build around 320 meters trek so that we can take the drinking rig at the top. Our target is that we have to complete it by tomorrow. We are working at… pic.twitter.com/Rt06YKWb50
— ANI (@ANI) November 18, 2023
The Indian Army has been deployed to build a trek to the top of the hill, from where vertical drilling will be done. Major Naman Narula said, “We have been given the work to build a trek so that we can do vertical drilling…We have to build around 320 meters trek so that we can take the drilling rig at the top. Our target is that we have to complete it by 9 AM tomorrow morning. We are working at war footing.”
The army official said around 150 people are working on it, and trees will be cut if needed to make the path. He added that at present one hole will be drilled as there is one machine, and around 80-100 meters will be needed to drill to reach the trapped workers.
Apart from this, another horizontal drilling from the Barkot end of the tunnel, the other end, will also be taken up. However, these two will be alternate options, the the drilling from the Silkyara will continue.
The third Rescue operation ongoing
Initially, it was believed that 40 persons were trapped inside the tunnel, but on Friday evenings officials said rescuers have now identified that 41 people have been trapped inside. According to officials, they have been monitoring the health of those trapped and they are safe. Additionally, officials have asserted that the temperature inside the tunnel is greater than outside conditions and there is no complaint of cold by persons stuck inside the tunnel.
Small steel pipes have been inserted through the debris, which is being used to supply air, water and food to the trapped workers. Communication devices have also been provided to communicate with them. Their health statuses are continuously monitored.
The official said, “Nuts, roasted chickpeas, popcorn, and medicines were being sent to them via a pipe every two hours.”
The officials supervising the rescue operation have asserted that while the progress in reaching the workers has been slow, the drilling machine has been able to drill a distance of 22 metres till Friday, approximately one-third.
They said, “We have made a significant progress and reached approximately 22 metres inside. Our goal is to reach the opposite side as quickly as possible.”
In the first four days of operations, two rescue attempts failed. In the first, rescuers tried to dig through the rubble using heavy excavator machines, but loose rock and sand collapsing from the roof of the tunnel impeded progress. Then they tried to drill a hole using an auger machine and fitting large pipes. But the attempt was stymied when the machine suffered damages after hitting a boulder.
At around 10:30 am on Thursday, the third attempt began using a heavier American auger machine transported from Delhi. The initial auger machine, boasting 35 HP (horsepower), could drill at a rate of 1 meter per hour. In contrast, the new 175-200 HP machine demonstrated the capability to cut through rock at a speed of 5 meters per hour. However, on Friday, this machine also encountered difficulties and has been unable to advance further.
Earlier during the rescue operation, the drilling machine had stopped after it hit a metallic object. After a halt of a few hours, the matching started working on Friday morning. As per officials, there could be a JCB machine or other similar earth-moving equipment of large size under the debris. This is why it is taking so long to dig through it and make a way for a safe escape.
It is important to note at this pace, even if operations continue uninterrupted under the current method, the rescuers will need at least two more days to reach the workers.
