Built by HCC in a joint venture with Halcrow Group of U.K., the ₹5,750 crore and 330 MW Kishanganga Hydro Electric Power project has achieved many firsts in the history of Indian infrastructure construction
Inaugurated by the Prime Minister of India, the Kishanganga Hydro Electric Power project is the first mega hydro power plant to be awarded as EPC to HCC by NHPC. Located at Bandipore in north Kashmir, the project envisages diversion of water of the Kishanganga River to the underground power house through a 23.25 km long head race tunnel (located 1.5km deep in the mountain) to generate 1,713 million units of power per annum. Apart from the many states which would be the project’s energy beneficiaries, 12% of the power generated will be provided to the Jammu & Kashmir.
KHEP is a $864-million dam, which is part of a run-of-the-river hydroelectric scheme that is designed to divert water from the Kishanganga River to a power plant in the Jhelum River basin. The project includes a 37m (121-ft) tall concrete-face rock-fill dam to divert a portion of the Kishanganga River south through a 24 km (15 mi) tunnel. The tunnel is received by a surge chamber before sending water to the underground power house, which contains 3 x 110 MW Pelton turbine-generators. After the power plant, water is discharged through a tail race channel into the Wular Lake. The drop in the elevation from the dam to the power station will afford a hydraulic head of 697 m (2,287 ft).
Challenges: Tunneling and TBM Logistics
The construction of the project began in January 2009 on three fronts: Head Race Tunnel (HRT), Power House and Ventilation Tunnel. The 23.65 km-long Head Race Tunnel carries the water from the dam to the powerhouse. The tunnel is constructed using two methodologies - 14.75 km tunnel is constructed by a Tunnel Boring Machine and the remaining 8.9 km tunnel is constructed by the conventional drill and blast method. This is one of the longest HRT in India with a maximum overburden (height of mountain above tunnel) of 1470m.
HCC team created a world record of the first successful Tunnel Boring Machine (TBM) operation in the Himalayan region and accomplished a national record by achieving the “highest tunnel progress in a month” of 816 meters in November 2012. While doing so, the team has successfully overcome several geological and engineering challenges.
A complex geology consisting of Andesite basalt and Meta siltstone along with some traces of granodirite were anticipated at the site. Besides the challenging Himalayan terrain, temperatures dropping to -23 degrees Celsius made the job tougher.
A big logistical challenge was in transporting the TBM up to Bandipora. It took three months to transport the 225m-long TBM with a cutter head of 6.18m to the project site via Mumbai in 160 containers. The convoy travelled about 2,300 kms and a major hurdle was crossing the Jawahar Tunnel connecting Jammu with Kashmir. The tyres of the special trailers were deflated so that the consignment could pass through the tunnel. At times, the convoy had to travel on winding roads with high gradients of 1:6 at some places.
Based on the detailed study conducted with the help of IIT Roorkee, the shear and squeezing zones, water pressure, and glow and geothermal anomalous conditions were predicted, and the appropriate tunnel boring machine was ordered from SELI, Italy. The double shield TBM with additional features to comply with the geological conditions of the Himalayan region was manufactured and mock assembled at SELI’s Aprillia factory near Rome.
Working like a giant earthworm, the TBM burrowed 14.5 km of tunnel through rock towards Gurez from Bandipora, even as it fixed concrete segments on the walls. From the Gurez end, the traditional drill blast method was used to bore 9 km of the tunnel. Starting May 2011, it took more than 30 months for the entire 23.24 km tunnel to be completed. According to the engineers at the site, this was the first time that a TBM was used successfully in the Himalayas.
More than its commercial value, KHEP is of great strategic value. It is an assertion of India’s rights under the Indus Waters Treaty. Besides being a feat of engineering in the Himalayan heights, and a successful “inter-basin” transfer of water from the Gurez Valley to the Kashmir Valley, and an assertion by India over the territory of J&K and its resources.
It was critical to complete the project at the earliest in view of the dispute raised by Pakistan in 2010 in the Hague’s Permanent Court of Arbitration (CoA), arguing that the Kishanganga Hydro Power Project violates the Indus River Treaty. On 20 Dec 2013, the International Court of Arbitration gave its final award, which unequivocally allowed India to proceed with construction of the Kishanganga Dam in Jammu & Kashmir.
Commenting on the project, Arjun Dhawan, Director & Group CEO, HCC, said, “The timely completion of this strategically important hydro power project along the LoC speaks volumes about HCC’s capabilities and scale of operations. Our team has soldiered to commission this project in the face of stiff challenges, countering logistical, geological and climatic hurdles, besides the odd shelling from across the LoC. This being the first major EPC project of NHPC, HCC has been involved in the whole lifecycle of the project, from design through construction and commissioning. Our nine decades of experience in developing crucial infrastructure in India has equipped us with the expertise to deliver complex projects such as KHEP, which we are proud to have inaugurated by our Prime Minister.”
Facts & Features of KHEP
KHEP is the largest EPC contract awarded by the Central government in the last decade. It is also one of the most complex to have been executed in recent times due to the following challenges:
- Three-unit, 330 MW power project to produce 1,713 million units of electricity annually
- Project being executed in the geologically complex Himalayan region
- Located in sensitive area (close of LoC) under very tough climatic conditions
- Remote location throws up logistical and connectivity challenges for transportation of heavy machinery, men and material
- Construction of head race tunnel done using tunnel boring machine (TBM) for the first time in the Himalayan region
- It was an integrated project with rockfill dam, tunnel, powerhouse being built under one single contract
- Winter temperatures at dam site around -23 degrees C
- Spread over 379 hectares across two valleys
- In Sept 2007, approved cost ₹3,642.04 crore; by March 2018, ₹5,750 crore
- 23.24 km of tunnel dug through rock with first successful use of TBM in the Himalayas
- Dam: Concrete Faced Rockfill Dam (CFRD) of 37m height
- Head Race Tunnel (HRT): 1 No, horseshoe/circular shaped 5.2m dia, 23.2 km total length
- Power House: Underground, 3 Units of 110 MW each (330 MW).