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Thursday , February 24 , 2000
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SSP dam stilling basin damaged


SSP DAM SITE, FEB 23: Major damage is reported to have occurred in the stilling basin of the Sardar Sarovar Dam compelling the authorities to carry out operations to clear the debris. The damage has occurred on the concrete floor of the basin, a few metres away from the main dam structure.

Repairs are yet to be carried out as the area is still water-logged. Electric motors of large horse-powers are being operated almost round-the-clock to pump out water.

The stilling basin is an integral part of the dam structure. It checks the velocity of falling water on the dam's downstream side in order to prevent damage to the dam's foundation.

This correspondent saw dumper trucks doing rounds to lift the debris scattered in a vast area near the dam's main structure during a visit to the site. While this debris is being lifted and dumped on either side of the Narmada waters nearby, a major portion has been dumped in river Narmada near Vadia village in Tilakwada.

Work to clear the concrete and rock structures has reportedly been on for the last two months. The damage reportedly occurred in front of the middle bays of the dam after the monsoon. The damage is at least the third of its kind since it occurred for the first time in 1994.

Superintending Engineer (Narmada dam) D D Parmar confirmed that the damage has occurred. He, however, hastened to add that it occurred every year. According to him, around 10,000 cubic meters of concrete has been washed off. The exact damage is not measurable as water is still in the stilling basin, he added. Financially, the damage runs to crores of rupees. ``Every year repair work is done before June,'' Parmar added.

``Whatever was constructed last year has been washed off,'' says Ramnik Mochi (named changed), one of the several drivers who drove around 30 kilometres to Vadia to dump the concrete material.

A talk with the drivers revealed that for more than a month, 15-tonne capacity dumper trucks did rounds round-the-clock to dump the debris. Shyam Vasava (name changed), another driver, says that the entire chunk of material has been dumped near Vadia to create a road. The gravel has been laid to smoothen the road, which is now used to bring in material.

It happens every year, claims another labourer working at the site. Vasava says that a few months ago several officers came in cars from Gandhinagar and instructions were given to take away the debris some distance.

Says Bhimsinh Tadvi, who earlier worked as a supervisor with the company which has been awarded the dam construction contract, ``the work is sub-standard''. He even alleges that engineers hardly visit the site for supervision.

The recent damage rakes up another issue. The repeated damage, alleges Shripad Dharmadhikari of the Narmada Bachao Andolan (NBA), ``indicates faulty planning and design of the stilling basin''. He also questions the quality of construction.

He says that the stilling basin has to be designed to withstand the flow of water at every dam height -- from low to high -- since the dam necessarily passes through all phases during construction.

The risk due to repeated damages, and large amounts of public money going waste, calls for a thorough public investigation by independent experts, Dharmadhikari says. He says the concrete structures could not have come from anywhere else other than the stilling basin.

Narmada Minister Jaynarayan Vyas says, ``The damage was anticipated. It hasn't surprised us. It is not at all alarming, there is no need to panic. The damage has been caused by an imbalance in the hydrodynamic forces. Unless the dam reaches its full height of 110 metres -- ideally it should reach 138 metres -- the damage may recur.'' Damage to the stilling basin won't have any impact on the dam, he says.

``We have referred the matter to the Board of Consultants appointed by the Narmada Control Authority. They are proposing some anchorage that will give stability to the stilling basin.''

Like Vyas, soil expert M D Desai, who constructed the Ukai dam, says the stilling basin could be damaged until the fullest height is reached and dam construction work in the beneficiary states of the project is over, so that water can be released in a controlled manner.

About why the stilling basin had not been designed to handle the flow of water at all dam heights, Vyas said nobody knew it would take so many years to complete the work. A.J. Gajjar, executive engineer (Narmada dam), denied any damage to the stilling basin. When probed further, he said concrete structures surfacing is an annual phenomenon. ``We are awaiting the expert committee report,'' he said.

Copyright © 2000 Indian Express Newspapers (Bombay) Ltd.


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