Andhra Pradesh

No main dam sans cofferdam, says panel

The Polavaram Dam Design Review Panel (DDRP) has rejected the proposal to build the main dam across the Godavari without a cofferdam. It took this decision after a meeting with Andhra Pradesh Water Resources Department engineers in New Delhi on Friday.

The National Hydro Power Corporation, in a report released a couple of days ago, said that the section of the dam built with earth and rock that stretches across the river be built without the help of a cofferdam (temporary embankment needed to create a dry area for construction on river bed).

The DDRP, which finalises the designs, rejected the proposal of the NHPC.

Andhra Pradesh Water Resources Principal Secretary Shashi Bhushan Kumar told The Hindu that the panel recommended building cofferdamas — one upstream and the other downstream of the main dam. This is the design proposed by the State Water Resources Department headed by Engineer-in-Chief M. Venkateswara Rao, he said. Mr. Kumar said that based on the minutes of the DDRP, the Central Water Commission (CWC) would give the final approval.

The Polavaram dam has two components — one Earth Cum Rock Filled dam across the main river and a concrete spillway across a diversion in the river. After passing the spillway the diversion rejoins the river.

While NHPC experts felt that a temporary dam across the main river 40 metres high having the capacity to withstand a flood of 23 lakh cusecs was sufficient, Engineering-in-Chief Venkateswara Rao explained that a dam or embankment 42.5 metres high with the capacity to withstand a flood of 28 lakh cusecs was needed.

According to the project design, a dam across the main river would help in impounding floodwater and divert it into a channel through the gates of the spillway.

Equipment seized

Meanwhile representatives of Dena Bank, which provided credit to the prime contractor Transstroy, got a court order to seize excavators mortgaged to it at the dam site on Friday. Bank sources said the principal advanced to the contractor was ₹84 crore, interest ₹36 crore putting the total dues at ₹120 crore.

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Printable version | Feb 25, 2021 11:15:40 AM | https://www.thehindu.com/news/national/andhra-pradesh/no-main-dam-sans-cofferdam-says-panel/article22379303.ece

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