Geological challenges lead to a first-of-its-kind design
All the components of the Tehri Pumped Storage project are located underground, essentially inside one hill within the vicinity of the existing 1000 MW Tehri Hydro Power Project.
The upstream and downstream surge shaft chambers were proposed to be 20-25m wide. As can happen with such projects, as geological information became available, it was apparent that the geological environment was too poor to construct chambers this wide.
Through extensive 3D analysis, including modelling rock bolting to replicate actual underground conditions, we re-planned the chambers and a width of 15m was determined as the best solution. However, the hydraulic conditions made it impossible to reduce the surge shaft diameter.
With a team of global experts in hydropower, tunnelling, and dams on the project, we designed a surge shaft chamber with the surge shaft slanting inward, in inverted form. “This is the first time such a solution has been adopted in India, and potentially worldwide,” says Prashant Agrawal, General Manager, Hydropower and Dams “It was made a reality through the vast experience of the global specialist team.”