A stupendous task has finally been accomplished. Excavation of the 7.2 km-long and 10m diametre Tunnel II of the Rs 2,813-crore Srisailam Left Bank Canal (SLBC) project, the longest in the State, has been completed about 350-500 metres underground in Nalgonda district.
The achievement made by using manual blasting method is expected to give a boost to the project which is expected to provide a solution to water woes of the fluoride-affected district. Village folks are jostling to see the tunnel that has become a tourist spot, with openings at Teldevarapalli and Neredugommu.
Tunnel II is only a segment of the project’s gravitation canal meant to draw Krishna water into a 7.54 tmcft capacity artificial lake being created at Teldevarapalli in Dindi Valley. Tunnel I, which will be the fifth longest in the world, spanning 43.9 km, will, in turn, bring these waters to the lake from Srisailam dam reservoir.
Dream project
Tunnel I is viewed as an engineering marvel as it is drilled through granite strata some 500 metres below Nallamala forest hill ranges. An 18-km of its stretch has been completed till now — 6 km down from Srisailam and 12 km upwards from DindiValley.
The late NTR, who took up this project to fulfil a long-cherished dreams of Nalgonda people and laid the foundation stone for its works in deep forests, had to give it up as the possibility of excavating tunnels of this magnitude at such depth, was ruled out at that time. Tunnel I, without any opening throughout its 43.9 km length, was held as necessary under Central guidelines to avoid disturbance to wildlife on the surface. A fully developed technology was unavailable then, nor was the cost within the Government’s reach.
Two giant tunnel boring machines (TBM) purchased by the firm implementing the project Jaiprakash Associates, from Robbins, US, for Rs. 300 crore each, made the job feasible.
The TMBs are excavating their way from both sides of Tunnel I, covering 30 metres daily each. Hundreds of engineers and workers labour in the mammoth subterranean burrow, receiving oxygen from outside.
Tunnel II opens into Pendlipakala reservoir from where the project’s open canal starts.
The tunnels will transfer 30 tmcft of water from Srisailam dam to the district to irrigate over 3 lakh acres and meet drinking needs of 516 villages.
R. Prabhakar Reddy, project advisor, says Tunnel I will be ready by December 2014. Once this project is completed, Puttamgandi scheme through which water is being brought from Nagarjunasagar to the district now, will be used exclusively for Hyderabad.
