Punatsangchhu-II is the second Project of the 10,000 MW initiative taken by the Royal Government of Bhutan (RGoB) and the Government of India (GoI) in May 2008, for development by 2020. Agreement between the GoI and the RGoB for implementation of the Punatsangchhu-II Hydroelectric Project was signed on 30 April 2010 by H.E. Shri S.M. Krishna, Hon’ble Minister for External Affairs on behalf of the GoI and H.E. Lyonpo Khandu Wangchuk, Hon’ble Minister for Economic Affairs on behalf of the RGoB. On the same auspicious day, the foundation stone of the Project was laid jointly by H.E. Dr. Manmohan Singh, Hon’ble Prime Minister of India & H.E. Jigmi Y. Thinley, Hon’ble Lyonchhen of Bhutan.
The Project is located on the right bank of Punatsangchhu along the Wangdue- Tsirang highway between 22 km and 35 km downstream of Wangdue Bridge. The dam site is about 94 km from Thimphu and connected by a highway. The project sanctioned at a cost of ₹/Nu. 37.78 billion excluding IDC on March 2009 price level with installed capacity of 990 MW (now revised to 1020 MW) is being funded by the GoI: 30% grant and 70% loan @ 10% interest p.a. repayable in 30 equated semi-annual installments commencing one year after the mean date of commercial operation.
Punatsangchhu-II Hydroelectric Project Authority (PHPA), an autonomous body was set-up for implementation of the Project on 08 June 2010. The project implementation started on 17 December 2010 with a completion schedule of 7 years including 2 years of infrastructure development.
The Punatsangchhu-II Hydroelectric Project is an environment friendly run-of-the river scheme. The Project area starts from dam site about 22km downstream of Wangdue bridge to Tail Race Tunnel which is located about 35km downstream of Wangdue bridge. The Project involves construction of the following:
Concrete Dam, 86m high and 213.5m wide at the top
Diversion Tunnel, 12m diameter, 888m long.
Four Desilting Chambers, each of 420m length x 19m width x 24.7m depth.
Layout of Dam, Intakes, Desilting Chambers& Highway Tunnel
Headrace Tunnel, 11m diameter, 8.6km long.
Surge Shaft, 31m diameter 137m height.
Three Pressure Shafts, 5.5m diameter 997m long & 6 penstocks of 3.86m diameter.
Underground Power Station, 236m x 23m x 51m size to house 6 turbo generators.
Tailrace Tunnel, 11m diameter 3.3km long.
Underground Transformer Cavern, 215.4m x 14m x 26.5m size to accommodate 20 single phase generator transformers each of 13.8kV/400kV & 70MVA capacity.
Two Double Circuit 400kV LILO with Punatsangchhu-I Transmission Lines.
Layout of Power House Complex
One Double Circuit 400kV line from PHEP-II to Jigmeling.
WAPCOS Ltd. (a Government of India Undertaking) are the engineering design Consultants to the Authority. The expertise of premier organizations of GoIe.g., CEA, CWC, Central Water & Power Research Station (CWPRS), Central Soil & Materials Research Station (CSMRS), GSI and Survey of India (SoI) are made available to the Project through WAPCOS.
The concerned RGoB authorities have approved lease/acquisition of 479 acres of GRF land, 14 acres of private land (involving 17 land owners) and 5 acres of Institutional Land (3 institutions) till the end of April 2013 for the project construction.
MAIN CIVIL WORKS
The Main Civil Works of the Project have been divided into three packages: C-1, C-2 & C-3
C-1: Construction of Diversion Tunnel, Dam, Intake and Desilting Arrangement including Hydro‑Mechanical works and Highway tunnel was awarded to M/s Jaiprakash Associates Ltd. at a contract sum of ₹/Nu.12.24 billionon 26 June 2011 with a completion time of 66 months.
C-2:Construction of Headrace Tunnel (HRT) from Adit I &Adit II was awarded to M/s Gammon (India) at a contract sum of ₹/Nu.3.98billionon 26 June 2011 with a completion time of 60 months.
C 3: Construction of Headrace Tunnel (from Surge Shaft end), Surge Shaft, Butterfly Valve Chamber, Pressure Shafts, Power House, and Tailrace Tunnel (TRT) including Hydro Mechanical works was awarded to M/s Jaiprakash Associates Ltd. at a contract sum of ₹/Nu.8.56 billionon 26 June 2011 with a completion time of 66 months.
MAIN ELECTRO-MECHANICAL (EM) WORKS
Generating Plant & Equipment: The first EM works contract of Generating Units and Associated Auxiliaries was awarded to M/s Bharat Heavy Electricals Limited, a GoI Undertaking (BHEL) at a cost of ₹/Nu.9.5 billion on 18 June 2012 with a completion period of 57 months.
Transformers: The second EM works contract of Generator Transformers, Reactors etc., was awarded to BHEL at a cost of ₹/Nu.1.07 billion on 08 April 2013.
Gas Insulated Switchgear: The third EM works contract of 420kV Gas Insulated Switchgear was awarded to Hyosung Corporation, South Korea at a cost of ₹/Nu.0.96 billion on 08 April 2013.
400kV XLPE Cables:The fourth EM works contract of 400kV XLPE cables was awarded to L.S. Cables, South Korea at a cost of ₹/Nu. 0.36billion on 08 April 2013.
The Authority has entrusted the execution of the transmission System to BPC, a RGoB Undertaking on ‘Deposit Work’ basis. POWERGRID is providing consultancy to the BPC.
CLEAN DEVELOPMENT MECHANISM (CDM)
Intention to get the Project registered for availing Carbon Emission Reduction (CER) benefits communicated to National Environment Commission (NEC), Bhutan, Ministry of Environment and Forest, GoI and United Nations Framework Convention on Climate Change (UNFCCC), was accepted by the concerned. Consultancy work of CDM Project was awarded to M/s ITP Synergy Ltd. & RITES Ltd. Consortium, New Delhi on 14th Jan., 2012 at a fixed fee of ₹/Nu. 3.0 million and Success-Sharing Fee of 0.29%.
The Project is scheduled to be completed in seven years w.e.f17thDecember 2010(zero date),the start date of construction i.e. on 17thDecember 2017.
The 1020MW Punatsangchhu-II Hydroelectric Project is envisaged to generate 4.36billion units in an average year.