Kerala submits proposal for new Mullaperiyar dam (The Hindu 02 October 2011)

Ahead of the October 10 meeting of the Empowered Committee headed by former Chief Justice of India A.S. Anand, the Kerala government has submitted the feasibility report for new Mullaperiyar Dam to be located at 366 m below the centre line of the existing dam.
According to the Kerala government, the old dam will be demolished only after completion of the new dam and as such diversion of river flow for carrying out the construction of new dam will not be a major problem.
The present arrangement of water diversion to Tamil Nadu will continue to function uninterruptedly during the construction of the new dam and also after its commissioning.
According to the 130-page report, a copy of which is with The Hindu the total estimated amount for the new dam is Rs.663 crore and it is to be built spread over a period of four years.
“It is a straight gravity concrete dam. The structure consists of a main dam and a small saddle dam on the right side. The spillway is located in river portion and is located +366.0m downstream of the existing old Mullaperiyar Dam. The favourable geomorphological conditions coupled with reduced additional area of submergence (26.33Ha) of flora and fauna make the location highly technically and environmentally acceptable. The new dam has been designed for earthquake forces also.”
The height of the new dam will be 52.16 metres (from deepest foundation up to road level) and its length will be 305.9 m (including piers) and bottom width will be 42.253 m. The crest level and FRL is kept the same and hence actually no shutters are necessary at 52.16 m.
But since the outflow is to be restricted to 1.22 lakh cusecs, whenever reservoir level reaches a particular level between 148 and 149 feet, the effective vent way is to be reduced by lowering the shutters to the required level.
The report says a special purpose vehicle is being created to carry out the effective and efficient management of the construction of the New Mullaperiyar Dam after obtaining all the mandatory clearances. Kerala will commission the New Dam most expeditiously and in the minimum time frame to safeguard the lives and properties of its thousands of people and to ensure continued supply of water to the needy farmers of Tamil Nadu.
Justifying the necessity for construction of a new dam, the report says, “There is a limit to the number of years one can keep dams in service through maintenance and strengthening measures. In the case of Mullaperiyar dam, the dam has to be there for another 884 years for diverting water to Tamil Nadu as per Lease Deed. This is an impossible proposition. All over the world, safety of dams is being reviewed as per modern standards and hundreds of dams have already been dismantled considering the safety aspects of human life and property.”
The report says, “In view of the definite conclusions of the scientific studies conducted by national institutions of repute and the persistent threat which the dam poses, it is imperative that the present old Mullaperiyar Dam demands urgent decommissioning for discharging the responsibility of the State to protect the lives and properties of its citizens.”