An engg marvel to give solace to power-starved state

A few hundred technocrats are inching towards the September 1998 deadline for commissioning the first of the four 250 MW generators as the fourth stage of the Koyna hydroelectric project has entered its final lap.

The engineering marvel giving a much needed solace to power-starved Maharashtra, poses to be the state’s premier peaking station. The Rs 1140-crore project will ensure optimum utilisation of available 67.5 TMC Koyna water for power generation within a shorter duration, Srikant Huddar, the Koyna project superintendent engineer told The Indian Express.

Indian engineers are using the state-of-the-art Swedish techniqueof lake bottom tapping for the first time at Koyna.

The sprawling Shivsagar reservoir of Koyna would be tapped for a two-way intake tunnel 12 kilometres upstream the dam wall. "Today, we are 10 metres below the lake bed," said Huddar associated with the project for over a decade.

"We will pierce up till six metres, then bore the holes for gelatin sticks right up to half-a-metre below the water," he said.

"Currently, the serge, pressure shafts are being given finishing touches with fitting of various valves and gates and erection of generators is underway," he pointed out.

The project engineer is planning to capture the million dollar moment of lake tapping by fixing video cameras right at the intake point.

"Surely it would be a proud moment for all of us who have been facing a plethora of oddities here in (rather under) Koyna," Huddar added.

Mind boggling tunneling has been a major feature of the project which is being constructed exploiting the steep gradients of Sahyadris. Steep inclinedpressure shafts, use of laser beam technology to bore a tunnel from base upward and the underground gas-insulated switch yard, part of an about 150-metre high rock-cut hall are some of the vital features of the final phase of the project. Only the naphtha-based Jhakri power project in Uttar Pradesh has a tunnel network matching the 17-km underground tunnel network linking all the four phases of the Koyna hydro project, available information indicates.

The French turbo-generator manufacturers Cegelec has supplied the generators which would also be set up for the first time in the country. The Koyna dam which has been in the eye of a storm in the wake of ongoing debate on reservoir-induced seismicity, at present feeds 920 MW capacity power stations in the first three phases of the project, besides catering to the irrigation needs of Maharashtra’s sugar bowl, downstream.

The project, "The lifeline of Maharashtra," as described by eminent economist late C D Deshmukh, was scheduled to be operational byDecember 1996 under the original plans, and has been about 21-months behind the schedule.

The delay was attributed to the hold up in finalising the details of the project, since this has been a World Bank-aided project. The total cost of Phase IV, at current rates, is estimated at Rs 1,140 crore with the WB loan to be used for civil and engineering work.

Phase IV would have a peaking capacity of two-and-a-half hours morning and evening, giving a total of about five hours a day. Since this is a hydro-project, it could go from rest to full generation levels within three minutes, while it would use the same quantum of water — presently being used by the first three phases of the project. The Krishna-Godavari inter-state water tribunal award has allotted 67.5 TMC of Koyna’s total 98.78 TMC water for power generation which could later be turned westward.

The total quantity of water being used at present under stages I and II will be shared under stages I, II and IV together. However, as the total generatingcapacity will increase under stage IV, the diversion of water in a day will be for a shorter duration, compared to the present utilisation. The water from stage IV will be released into the Kolkewadi reservoir and will be reused in stage III.