The Idukki Golden Jubilee Extension Scheme, which envisages a second, 800 MW power station in Idukki, is designed to have minimal impact on the environment, according to the Kerala State Electricity Board (KSEB).
That said, the scheme also offers some complex technical challenges. Much of the civil construction, including the power station, will be positioned underground with minimal disturbance to the forestland above. The tail-race water, after power generation, would be let out into the Thodupuzha river, the same as the existing 780 MW power station, KSEB officials said.
Tail water
An important question pertains to whether the Thodupuzha river and the Malankara dam can accommodate the tail water. A senior KSEB official said that the pre-feasibility study by the WAPCOS showed that they could. One option is the construction of a balancing pool/reservoir downstream to hold the outflow, but this would require additional land.
A second engineering challenge is the construction of the actual structures, majority of which, including the 800 MW power station, will be positioned underground, according to the pre-feasibility study. This includes the 1.9-km head-race tunnel, surge shaft, pressure shaft, and the 1.46-km tail-race tunnel. The powerhouse, which will be equipped with four 200 MW generators, also is to be housed in an underground cavern.
Land requirement
The project also required 16 hectares of private land for the construction of the switch yard and transmission facilities, the KSEB officials said.
