Hirakud dam spillway stuck in approval delay in Odisha

Over two years have passed since the Odisha government planned an additional spillway to protect the dam as per the Central Water Commission's (CWC) recommendation.
Hirakud dam spillway stuck in approval delay in Odisha

BHUBANESWAR: Every time there is a flood in the Mahanadi system, Hirakud, the world’s longest earthen dam gets everyone’s attention. Strategies to improve its water-carrying capacity and structural safety are chalked out. But everything goes back to square one once the phases passes.

Over two years have passed since the Odisha government planned an additional spillway to protect the dam as per the Central Water Commission's (CWC) recommendation. But the project is yet to get the required administrative approval. Of the two spillways planned five years ago, one was taken up by a joint venture (JV) of Tata Projects Limited and Turkey-based AGE Group at an estimated Rs 369 crore under the World Bank (WB)-funded Dam Rehabilitation and Improvement Project (DRIP).

However, the project got stuck after the JV backed out citing delay in resolution of displacement issues. In 2020, the government cancelled the work contract and decided to construct the additional spillway with its own funding through Odisha Construction Corporation (OCC). But it is yet to be decided whether one or two spillways will be constructed.

The estimated cost of the single spillway has now been revised to Rs 786 crore and as it is more than 15 per cent of the preliminary estimate, the Finance department had sought some clarifications, which the Water Resources department has already complied with.

Sources said the project is caught in the delay in decisions on the number of spillways to be constructed. “Several rounds of discussions have been made on whether we should go for two spillways or one. If one spillway is to be constructed instead of two, then the present plan and design require some modifications, which is why it is getting delayed,” the sources said.

The spillway is critical to Hirakud’s health because it can decrease load of water on the dam in case the reservoir reaches a peak maximum flood (PMF) level caused by extreme precipitation events. The CWC had reviewed the inflow design flood and pegged PMF at 24.5 lakh cusec in 1997. As the existing total discharge capacity stands at 15 lakh cusec through 98 gates, effective discharge is about 13 lakh cusec due to operational constraint of few gates. Once two spillways are built, the discharge capacity would increase to 18 lakh cusec.

Engineer-in-chief (water resources) Bhakta Ranjan Mohanty said all technical formalities for spillway construction are being looked into. “Hopefully, we will reach a conclusion within a month and approval will be obtained,” he added.

Meanwhile, a team of experts of the Central Soil and Materials Research Station, New Delhi studied the cracks in different structures of Hirakud reservoir. Though the team found no immediate threat to the dam, it has proposed a detailed assessment of downstream face for locating any cracks and underwater videography of upstream concrete spillway to check its condition as it could not be inspected visually.

Official apathy

 A spillway planned five years back got stuck after the JV backed out of theproject
 It is yet to be decided whether one or two spillways will be constructed
 The estimated cost of the single spillway has been revised to Rs 786 crore

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