The site of the Kameng hydro-electric project. Picture by Rajiv Konwar

Kimi (Arunachal Pradesh), Oct. 15: There will soon be light at the end of the tunnel, literally.

Engineers of North Eastern Electric Power Corporation (Neepco) Limited are just 3km away from breaking out through the mountains to complete construction of a 14.5-km-long tunnel for the Kameng hydroelectric project, nestled in the hills overlooking Kimi and straddling two rivers in West Kameng district of Arunachal Pradesh.

The tunnel starts at Bichom river, a tributary of Kameng (Jia Bharali in Assam), and passes through hills and under the Tenga river (Bichom’s tributary) before ending at Kimi where it would release water at a speed of 5km/second to turn four turbines to generate 600MW of power.

The run-of-the-river project is Neepco’s biggest venture since its inception in 1976.

Besides the 69-metre-tall Bichom dam, a 24.5-metre-tall dam on Tenga is being constructed to supplement water requirement of the project during winter when the water from Bichom would be insufficient for constant supply to the Kimi project, 160km north of Tezpur in Assam.

Neepco is determined to complete the project by June 2016, a seven-year time overrun caused by “geological” and “geographical” conditions.

Work on the project, which was earlier scheduled for completion in 2009, started in 2005.

“The rock condition at the project site was different from what was mentioned in the initial report based on which the work started, delaying the tunnel construction process. Besides, in 2008, floods washed away our machines and dealt a blow to the infrastructure, further setting us back. Communication was another big challenge. However, we are hopeful of completing the project by 2016,” said Dilip Kumar Nath, executive director of Neepco (Hydro).

Assam’s share in the project is 65MW while Arunachal Pradesh has agreed to purchase 300MW from it.

Although the distance between the project and Bichom is just 14.5km, it is 175km by road. Similarly, the road distance between the Tenga dam and the project is 46km.

Roads are undulating, spiralling and at a high altitude, sometimes over 5,000 feet from sea level. During the monsoon, often avalanches of stone or landslides block them. “Sometimes roads are blocked for several days. Besides, given the distance between the project sites and the plains we have to wait for days to bring in a part of a machine or for repairs,” said Sanjeev Baruah, general manager and head of the project.

The delay has escalated the project cost two-fold. The cost, which was estimated to be Rs 2,496.90 crore initially, has increased to Rs 5,139 crore. Neepco has submitted the proposed revised estimate to the Central Electricity Authority.

The MoU for execution of the project was signed between Neepco and the Arunachal government in 1999. In 2004, the Cabinet Committee on Economic Affairs accorded clearance to complete it by 2009.

Neepco officials said the Central Water Commission carried out a dam-break analysis for both the dams, concluding that the spillways and sluices for both have adequate capacity to negotiate probable maximum floods.