Minimizing Civil Works Cost of Dam Based Schemes

Project: Brindavan River:  Cauvery Capacity: 3 x 3500 kW
Click to Go Back to Main Page State: Karnataka Energy:  62 GWh/year

Dam based schemes such as Brindavan especially in Karnataka state typically required as per  the original proposals extensive excavation through rock in order to construct entirely new intakes and tunnels to by-pass the sluices in the existing dams.  In the new layouts, the existing sluices are fitted with a trash rack, gate or stoplog,, hoists and a  bellmouth made of RCC. Steel  penstocks are to be anchored in the existing sluices to which the turbines are fixed. Conical straight draft tubes convey the water to a rectangular pool from which the existing canal starts.


The original layout involved extensive civil works (i.e., excavation of rock shown in red and with downstream elbow turbine shown on right) to construct a by-pass channel to divert water from the existing reservoir through a powerhouse and into the existing canal. The revised layout (shown in green with tubular turbines on left) eliminates  the tunnel by using the existing irrigation sluices as the intake for the proposed mini-hydro scheme.
At 1990 prices, the original layout  required an expenditure of Rs. 9.6 million, Rs. 3.6 million, and Rs. 3.4 million for the intake structure and tunnel, the powerhouse structure, and the tailrace/spillway structures respectively. By eliminating the tunnel and simplifying the powerhouse structure, the expenditure would be reduced to about Rs. 2.0 million; a savings of about Rs. 10 million in the cost of civil works. A detailed breakdown of cost estimates for civil works are presented.


Civil Works Component

Estimated Costs in (Rs. million)

  Original Layout Revised Layout
Intake Channel 7.00 0.43
Inlet Tunnel 2.65 -
Power House 3.56 0.67
Tailrace 2.56 0.50
By-pass/Spillway 0.86 0.07
Miscellaneous 0.32 0.15
Total 16.95 1.82

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