GANGTOK: Over a year after the deadly glacial lake outburst flood (GLOF) in Sikkim, which caused significant damage and washed away a major dam of the Teesta-III hydroelectric project, the Environment Ministry has approved a proposal to build a new, taller concrete gravity dam in its place.
This new dam will be 118.64 meters high and is set to replace the previous 60-meter-high rockfill concrete dam. The approval was given by the Ministry’s Expert Appraisal Committee (EAC) on January 10, 2024, despite concerns about the dam’s safety and the design being unapproved yet.
The flood, triggered by the burst of the South Lhonak glacial lake in October 2023, killed 40 people and destroyed the 1,200 MW Teesta-III Chungthang Dam located 55 km downstream.
Following the incident, the EAC formed a sub-committee to evaluate the new dam’s feasibility and safety. While the new concrete gravity dam is considered stronger, it is also more expensive to build.
During their review, the EAC noted that the design of the dam had not been fully approved by several key agencies, including the Central Water Commission (CWC) and the Geological Survey of India (GSI).
They also raised concerns about the dam’s ability to withstand future floods, especially considering the risks of another GLOF. However, Sikkim Urja Ltd, the project operator, has upgraded the dam’s spillway capacity to handle larger floods.
There were also concerns about the potential dangers posed by upstream glacial lakes, with the company identifying 13 such lakes as potentially hazardous. Despite these ongoing concerns, the EAC approved the proposal without calling for a fresh public hearing, citing that no new land acquisition or displacement was involved.
Independent experts have questioned the speed of the decision, urging for updated flood studies and a new environmental impact assessment.
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