Aug 2024: Massive Landslide damages NHPC’s Teesta V Hydropower station

A massive landslide (location: [27.2515, 88.4594]) at Dipu Data near Singtam in Gangtok district that brought down a huge part of a hill above the power house of the NHPC’s 510 MW Teesta V hydropower project on Teesta river in Sikkim at 7.30 in the morning of Aug 20 2024 has damaged the power house. The GIS building above the underground power house located at Balutar can be seen getting destroyed in the massive landslide and getting buried under the debris. The project has been out of operation since the Oct 4 2023 GLOF disaster in Teesta river [i] had over topped the dam and seriously damaged the project.

Photo of the Teesta V Power House of NHPC in Nov 2023 (Photo by: https://savethehills.blogspot.com/)

Fortunately, no causalities have been reported from the latest disaster affecting this project as after the recent smaller landslides at the same location, the buildings of and around power house were evacuated. A large number of videos[ii] shot by the nearby workers and others are available on social and electronic media. The landslide had damaged the NHPC GIS (Gas Insulated Switchgear) building and six residential houses belonging to local citizens. Large cracks have developed along the Singtam-Dikchu road, rendering it inaccessible[iii].

East Mojo [iv], NDTV [v] and even ANI reported that the power house of NHPC’s Teesta V HEP has been totally destroyed. Mint reported [vi], “Another dam has collapsed at the Teesta power project in Sikkim in less than a year.” All these seem inaccurate.

However, it is not clear how much damage has been caused to the underground sections of the power house. According to one report: “Officials said the station’s powerhouse experienced heavy damage, in addition to the GIS building on site. This report also described: “In 2019, Teesta V was rated as an example of international good practice in hydropower sustainability, according to an independent report. The station was reviewed by a team of accredited assessors using the Hydropower Sustainability Assessment Protocol (HSAP). The assessment, the first of its kind in India, was conducted between January and June 2019 and involved two visits to the project area, with stakeholder interviews.” Both International Hydropower Association and HSAP have become a laughing stock after multiple disasters the project has faced.

“As a Gangtok District Disaster Management Authority report on facebook [vii], a technical team from NHPC is travelling from Delhi to assess the extent of damage and decide about the remedial measures. The Gangtok district collector has directed the Department of Mines and Geology to conduct a detailed investigation of the landslide and provide recommendations for short-term and long-term restoration efforts.

Above map by SANDRP shows the location D as that of Teesta V Project dam and after a 17.106 km long tunnel its power house is just upstream of location of Teesta VI dam (under construction) marked at No. 30.

By way of initial response, Prof. David Petley, international expert on landslides and the Vice-Chancellor of the University of Hull in the United Kingdom told SANDRP on Aug 20 that following the massive flood in the Teesta river in the aftermath of the Oct 2023 Glacial Lake Outburst Flood (GLOF) the Teesta V power house, “site was really badly affected by the flood – the pictures are very stark – so a very initial response would be that the toe of the slope was eroded by the flood, leaving the slope inadequately supported” as a possible reason for the landslide on Aug 20 morning. However, he added that further work is required before this can be confirmed.

This is not the first time that a massive landslide has badly damaged the Teesta V hydropower project of Sikkim. It has already happened on a number of earlier occasions including in March 2023 [viii], June 2020 [ix], among others. There have been other disasters [x] related to the project.

Following the disaster, media has been quoting NHPC official statement, but no such statement is available on NHPC website [xi] or its official twitter [xii] page. Business Standard quoted NHPC statement [xiii] saying: “the company confirmed the mishap, stating that several structures of the plant have been affected due to the landslide. NHPC mentioned that the Teesta Basin Region has been subject to periodic natural subsidence and landslides… Today’s incident of a landslide at NHPC’s 510 MW Teesta-V Power Station (Sikkim) also occurred due to subsidence/landslide over the Tail Race Tunnel (TRT) outlet structure and behind the GIS Building. This has affected the TRT Gate hoist structure and part of the GIS Building.”

Interestingly, Congress criticised the government on Aug 21 2024 [xiv] that hydropower projects are coming up in the ecologically fragile Himalayan region in the past few years without adequate thought to their cumulative environment impacts. It also asserted that he dams on the Teesta River are the prime example of how ecology is being fundamentally altered with grave consequences for this and future generations.

In his blog on Aug 21 2024, Dave Petley [xv] wrote: “Whilst I cannot say definitively, there are indications in this image that the slope may have been altered. If so, failure less than two decades later would ask serious questions about the engineering at this site. Of course, there is also underground infrastructure here, so there are other ways in which the integrity of the slope might have been damaged… The second question related to the fact that this area was affected by the massive 4 October 2023 glacial lake outburst flood (GLOF) from South Lhonak, which caused immense damage along the Teesta. Whether the slope was affected by the flood, either through direct erosion of the toe or by changes to toe buttressing, for example? At this stage there is insufficient information to know.”

Some serious questions Petley warned: “It is clear that the planning of these projects is repeatedly failing consider adequately both the complex geological settings and the occurrence of events that can cause complete loss of these pieces of infrastructure… This situation is only going to get worse. The rate of warming caused by anthropogenic climate change in these high elevations is rapid, and we have strong evidence from around the world that this is increasing the rate at which large rock slope failures are occurring… This is an urgent issue – many more hydroelectric projects are planned in the Himalayas, but it appears that no actions is being taken… We cannot continue like this.”

The series of disasters in Sikkim, across Himalayas and also at other dam sites across India raise these and many other questions. But will we get any honest answers?

SANDRP (ht.sandrp@gmail.com)

POST SCRIPT: The Nagaland University scientist Dr Manasi Debnath analysed the satellite images of the landslide site and highlighted the role of manmade reasons and not extreme weather events behind the event. “There was no presence of vegetation over the slid hills. The hill slope is inclined to more than 45 degrees showing the possibility of high soil erosion due to manmade activities (including NHPCs construction work) from both sides caused pressure over fragile phyllite stone” said Debnath who is researching GLOF in Sikkim.
– Besides, Debnath also underlined huge rainfall in the region in June and July would have also possibly triggered seepage through porous phyllite stone. It would have loosened the soil in the region which unsuitable for huge construction activities.
https://www.newindianexpress.com/nation/2024/Aug/21/man-made-activities-triggered-landslide-at-teesta-dams-power-station-say-scientists Aug 21 2024

PS2: In discussion with a TV Channel, NHPC CMD said on Aug 29 2024 that rehabilitation of the Teesta V power house will take at least an year. https://www.youtube.com/watch?v=J1J5X3eP-rQ

PS 3: Sept 6 2024 This photo blog from Save the Hills Darjeeling very well explains the ground situation post Aug 20 2024 landslide at Dipudara in Sikkim, which buried part of NHPC’s Teesta V Power house.
1. This structure on the banks of Teesta just below the landslide was totally destroyed and buried as can be seen in the next photo. This photo was taken on 19 Nov 2023. Both photos, thanks to Save the Hills.