Tehri Hydel Power Project: A Profile

(As of 30 January 2001)

he Tehri Hydel Power Project is being implemented by Tehri Hydro Development Corporation Ltd. Located in the Tehri Garhwal district of the State, this is the largest investment project in the State. The project envisages the construction of a 260 metre high rockfill dam at the intersection of two rivers – Bhageerathi and Bhalingna[d1] . This huge water reservoir, with 1,500 metre wide base, would irrigate 2.7 lakh hectares of land, and generate 2,400 MW of hydro-electric power.

The project is divided into three phases. In the first phase, currently being implemented at an outlay of Rs.4,657 crore, 1,000 MW of power generating capacity would be installed through four submerged turbines of 250 MW each. An identical capacity would be added in the second phase, while the remainder 400 MW (through surface generators) has been envisaged in the last phase.

The project implementing agency, Tehri Hydro Development Corporation (THDC), is a 75:25 joint venture between the Union Government and the Uttar Pradesh State Government, incorporated in July 1988. The project, conceived as the State government’s responsibility, was transferred to THDC in June 1989. The Union Government cleared the project in March 1994 and made an annual commitment of Rs.300 crore towards the project cost.

The project that experienced a delayed start (See Tehri Dam: Environmental Issues) is currently under active implementation. As per latest information available, the foundation of the main dam has been laid, and this would be increased to a height of 15 metres. All the four diversion tunnels of the main dam have been constructed, and so has been the coffer dam. With regard to power generation, Bharat Heavy Electricals Ltd (BHEL) has been awarded the contract for the supply and commissioning of power generators.

Meanwhile, THDC is passively implementing the phase III of the project. This phase entails the construction of a minor dam that would act as a balancing reservoir to operate the 400 MW (4x100 MW) surface powerhouse. Global tenders, inviting pre-qualification bids for this phase, were floated in May 1999. The turnkey contract entails the supply of the generating plant, auxiliary equipment and services.

Tehri Dam: Environmental Issues: The Tehri Dam Project has been in the thick of controversy for the past two decades; the controversy emanating from environmental issues such as the displacement of local inhabitants (estimated at around 70,000) and permanent destruction of agricultural land. These issues, though they sowed the seeds of controversy, now seem trifling. It is the grave ecological consequence of the project that forms the backbone of the present antagonism.

Leading geologists strongly feel that the benefits of the dam are short-lived, and that the construction of the dam can have devastating effects on the State. They aver that owing to the high siltation rate (rate at which silt would get deposited into the reservoir), the life of the dam would only be around 30 to 40 years, as against 100 years projected by the implementing authorities. This challenges the basic objective of the project.

More importantly, the dam is being constructed in a low seismic zone – an area highly prone to earthquakes.  In the event of an earthquake – a distinct possibility during the lifespan of the dam – the dam could burst, with a potential of submerging cities like Hardwar and Hrishikesh.

Protesting local inhabitants and environmentalists obstructed the project construction work during April and May 1995. The government however overruled the protests on the strength of a project review carried out in July 1995. The Government, later in June 1996, constituted a Group of Experts to further examine the safety aspect of the Tehri Dam. The Group, in its report, stated, “the design of the dam was safe to withstand the Maximum Credible Earthquake”.

Despite the government’s repeated assurances about the safety of the project and the fact that the Tehri Dam Project is very much under implementation, a section of geologists and environmentalists still feels that a careful reappraisal of the project is necessary.