NHPC’s Teesta power station damaged due to landslide

New Delhi: The 510 MW Teesta 5 power station of National Hydroelectric Power Corp. (NHPC) in Sikkim has been damaged a severe landslide on Tuesday.

In a statement, NHPC said that the landslide has affected the "TRT Gate hoist structure and part of the GIS Building". However, no casualties have been reported so far as the power station was evacuated in the past few days amid frequent landslides.

NHPC’s expert team from the corporate office is visiting the project to assess the situation, take stock of losses and plan for remedial works, the statement said.

The Stage 5 dam was defunct since the October 2023 glacial lake outburst in the Teesta River basin that had damaged Teesta Stage 3 dam of Sikkim Urja Ltd. The cloudburst triggered a massive flash flood that washed away parts of the dam at Chungthang, the biggest hydropower project in Sikkim. Rising waters flowed through unabated in North Sikkim's Mangan district.

These floods happen when glacial lakes formed by melting ice accumulate water behind weak moraine dams. Unlike sturdy earthen dams, the moraine dams can fail abruptly, releasing large volumes of water in minutes to days, leading to devastation downstream. 

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Tuesday’s landslide at NHPC's 510 MW Teesta-V Power Station affected the hoist structure of the tail race tunnel (TRT) outlet—that carries water out of the power plant—and the GIS building (high-voltage substation), according to the NHPC. The power plant is currently not operational and undergoing restoration work after the flash flood of October 2023, it said.

Last October, NHPC told the stock exchanges that its two units--Teesta-V power station (510 MW) and Teesta-VI HE Project (500 MW)--were affected due to floods in Sikkim’s Lachen Valley. 

Sikkim has been badly hit this year due to incessant monsoon rain. In June, at least six people were killed and around 2,000 tourists were stranded in the Himalayan state because of landslides and floods after 36 hours of heavy rainfall. So far in the four-month monsoon season (June-September), Sikkim has received 32% more rainfall than normal compared to 4% above normal precipitation across India at 642.9 mm, according to the India Meteorological Department.

At least 179 people had died last year in Sikkim when a Himalayan glacial lake outburst triggered floods.

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