Rescue operations at the Silkyara Tunnel in Uttarkashi, where 41 workers remain trapped, continue.

The 2 km section of the tunnel, with completed concrete work ensuring the safety of the workers, is the focal point of the rescue efforts.

Various government agencies are working on assigned tasks to ensure the safe evacuation of the workers.

National and international experts are present at the site to provide advice on the rescue operation.

NHIDCL Lifeline Efforts

Freshly cooked food and fresh fruits are being inserted inside the tunnel at regular intervals using the second lifeline (150 mm dia) service, which has been extended from the initial position to a distance of 12 m to ensure higher stability and safety.

A consignment consisting of roti, dal, mixed vegetables, and fruits like apples, oranges, bananas, etc., along with medicines and salts has also been supplied.

A modified communication system with wire connectivity developed by SDRF is being used for communication regularly. People inside have reported that they are safe.

Horizontal Boring by NHIDCL

Auger drilling started at 12:45 AM on November 22, 2023, but was halted due to a metallic object (Lattice girder rib) being encountered in front of the pipe, and the pipe could not be inserted further. Cutting of the metallic object (Lattice Girder rib) using gas cutters has been completed. Pushing of the 9th pipe reached an additional 1.8-meter distance.

When a minor vibration was noted, the auger was pushed slightly back to reassess the force to be applied. Obstructions were observed.

A bent part of the forepole (pipe) from tunnel lining was stuck in the auger assembly, which led to vibrations.

Strengthening of the platform for the auger machine using an accelerating agent for rapid hardening of concrete is completed.

The platform for the auger machine has been strengthened by way of anchoring, bolting, concreting foundation, etc.

Further, the auger was required to pull back fully to assess any other damage to the pipe. Auger pulling has been completed. GPR (Ground Penetration Radar) test has been completed. Cutting of the bent pipe is completed too.

Auger re-assembly work was completed and reinserted by 1430 hrs. After placing of auger 800 mm dia, the next pipe fitted will be placed in position in line with the auger drilling machine.

Placing, positioning of the next pipe is under progress, and pushing will commence after completion of welding joints.

Vertical Drilling for Rescue by SJVNL

The platform for launching the drilling machine has been completed. Marking of the drilling point over the tunnel has been finalized.

Horizontal Drilling from Barkot Side by THDCL

THDC has initiated the construction of a rescue tunnel from the Barkot end, with four blasts already completed, resulting in a 9.10-meter drift.

Shotcreting and rib erection have been completed, and additional rib fabrication work is in progress.

Perpendicular-Horizontal Drilling by RVNL

Equipment for micro tunneling required for horizontal drilling to rescue labourers has reached the site. The platform is likely to be completed by November 24, and the equipment is to be set up by November 25, 2023.

Vertical Drilling (6 inches) by RVNL at Silkyara end

The access road of 1,150 meters has been completed by BRO and handed over to RVNL. The machine for drilling towed to the location by BRO. Vertical drilling is likely to be completed by November 26, 2023.

Vertical Drilling Toward Barkot End by ONGC

An air drilling Rig machine from Indore has reached the site. Submission of the report by ONGC will be made after the completion of the field survey.

Drift Tunnel by Manual-Semi Mechanized Method by the Joint Team of THDCL/Army/Coal India and NHIDCL

Work is underway to create a drift inside the tunnel. The Army is mobilizing box culverts for this purpose. Fifteen numbers of frames have been fabricated.

Road Cutting and Supportive Work by BRO

The BRO has completed the construction of the approach road for vertical drilling by SJVNL and RVNL.

BRO is also building an approach road for ONGC, with geological surveys conducted by ONGC. Seven hundred meters of the approach road have been constructed so far.

Recap

On 12 November, 2023, a collapse occurred in the under-construction tunnel from Silkyara to Barkot due to debris falling in a 60-meter stretch on the Silkyara side. Immediate mobilization of resources by the State and Central Governments ensued to rescue the 41 trapped laborers.

Initially opting for a 900 mm pipe through the debris, safety concerns led to the exploration of multiple rescue options simultaneously. The area of entrapment, measuring 8.5 meters in height and 2 kilometers in length, is the built-up portion of the tunnel, offering safety to the laborers with available electricity and water supply.

Five agencies—ONGC, SJVNL, RVNL, NHIDCL, and THDCL—have been assigned specific responsibilities, working collaboratively with occasional task adjustments for operational efficiency.