Orissa Hydro Power Corporation.
Diversion Tunnels were constructed in Orissa's Balimela, Upper Kolab & Upper Indravati Hydro Electric Projects to divert the summer flow of the river to facilitate the construction of dams across the main river channel. Subsequently, the diversion tunnels were to be plugged with concrete plugs after lowering the gates through the gate shafts with a view to bring workable conditions inside the tunnel at the plug areas. The present paper highlights the construction problems faced during plugging in each of the three projects, all arising out of a single reason which is excessive leakage through the gates. The author was associated with the construction of all the three projects at different times and he outlines the construction problems faced and the remedial measures taken at exhorbitantly high cost. The author feels that the authorities’ construction planning should have been better to provide reliable controlled structures at the gate shafts to reduce the leakage through the gates to a minimum workable discharge. Even though the projects have been commissioned since long, these crucial issues were never highlighted earlier through published papers. These experiences may be of some help to the construction Engineers of the present generation who would be executing similar works in future.
