Work on inlet side of SLBC tunnel resumes after a gap of about 13 months

About a month after work on the Srisailam Left Bank Canal (SLBC) tunnel resumed from the outlet side, the work on the tunnel excavation from the inlet side also resumed on Friday (March 20), as part of the government’s plans to fast-track the work, Minister for Irrigation and Civil Supplies N. Uttam Kumar Reddy announced.

Work on the tunnel from outlet (Devarakonda) side was resumed in the third week of February, and from the inlet (Domalapenta near Srisailam dam) side was resumed on Friday. “The government aims to complete the world’s longest tunnel excavated without any intermediate access shafts,” the Minister said. The tunnel runs for 43.93 km between Srisailam and Dindi reservoirs, as per the design.

Another tunnel linking the Dindi reservoir to the main canal of the Alimineti Madhava Reddy Project (AMRP) runs for 7.13 km to complete the tunnel project.

The Minister chaired a high-level review meeting to assess the progress of the SLBC tunnel, the Dindi Lift Irrigation Scheme and the Achampet branch canal. Stating that the government was giving top priority to workers’ safety following the accident of 2025 February due to tunnel roof collapse at about 14 km inside the mouth of inlet, the Minister insisted on ensuring proper ventilation right up to the last point of the tunnel face, along with continuous monitoring and deployment of all necessary safeguards.

The February 22 incident of last year had buried alive 8 workers, technicians and engineers and only two bodies were retrieved after over a month-long exercise involving several national and State-level agencies.

The resumption of tunnel work from the inlet side comes after preparations including a 20-metre open cut and deployment of additional safety installations. The progress made from the outlet so far is about 50 meters as the tunnel traverses challenging quartzitic and granitic formations crossing 15 nalas, four of which being perennial streams.

To better understand subsurface risks, a helicopter-borne VTEM Plus Magnetic Geophysical Survey (Heli-borne AEM) was conducted over more than 200 km of the alignment by experts from the National Geophysical Research Institute (NGRI). The survey’s data, penetrating 800-1000 metres deep, helped identify shear zones, water bodies and other hazards for tailored excavation strategies, Mr. Uttam Reddy explained.