AMR SLBC tunnel project has a long way to go for completion

The project, initially known as the Srisailam Left Bank Canal Tunnel Project, has been on cards since 1983. But the works on the project commenced only in 2006.

Hyderabad: Moves are afoot to resume work on the Alimineti Madhava Reddy SLBC tunnel project very soon. The ambitious project, said to be the world’s longest tunnel without intermediate access, was intended to transfer floodwater from the Krishna River at the Srisailam project to the erstwhile Nalgonda district. This tunnel aims to provide irrigation to 4,00,000 acres and clean drinking water to 516 villages along its route.

The project, initially known as the Srisailam Left Bank Canal Tunnel Project, has been on cards since 1983. But the works on the project commenced only in 2006. It was designed to address the water needs of fluoride-affected areas in Nalgonda and parts of Nagarkunool. The tunnel, once completed, will span 43.5 kilometres, making it the longest of its kind in the world.

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Two 10-metre diameter double shield tunnel boring machines (TBMs) engaged in the work were assembled onsite to undertake this massive task. However, tunnelling progress has been hampered by significant geological challenges. A major portion of the tunnel passes through a shear zone with a strongly deformed crust, causing delays and mechanical issues. Consequently, the project deadline has been extended six times. Despite these setbacks, the government is keen on resuming work in the coming months, with a target to complete the project by June 2026. However, the availability of TBM components and funding issues remain significant hurdles. The revised project cost is estimated at Rs.4,658 crore, with Rs.2,646 crore already spent. Currently, a 20.5 km stretch of the tunnel is ready from one end, and another 14 km was completed from the other end. The remaining 9.5 km pose the most challenging task due to heavy seepage.

Efforts to address the seepage issues have been ongoing for the last eight months. As of November 2020, both TBMs had excavated at least 70 per cent of their respective stretches. The project has faced extremely hard and abrasive rock conditions, necessitating the use of more durable cutter rings. A cabinet minister from the State, accompanied by officials, recently visited Ohio, to ascertain the availability of the necessary components for the TBMs.

A senior officer from the Irrigation Department expressed optimism about resuming work soon, despite the challenges. The successful completion of this tunnel will be a significant milestone, providing much-needed water resources to the region.