Design and Construction Aspects of Pressure Shafts of Teesta-III Project

The Teesta-III HE project (1200 MW) is under construction and is slated for commissioning by June 2015. The project involves construction of steel lined pressure shaft (2 Nos) of 1.4 km each including the vertical shaft of 650 m. The conventional working by way of one activity at a time would have taken more than 36 months to complete. However innovative construction planning by way of concurrent working like fit-up, welding, NDT and concreting works being done concurrently reduced the cycle time substantially. The detailed erection methodology was planned for taking up activities in tandem which required high capacity winch, wire rope, series of platforms separately for welding, NDT and concreting to ensure that all works goes smoothly. The concreting was planned from bottom through high capacity pump so that even this activity is handled separately. This paper deals with various aspects of design and erection methodology of steel liners for this Teesta-III pressure shaft, which can be a great experience for other projects in similar situations.