Xe Pian & Xe Namnoy Hydropower Scheme Lao PDR Client Dong Ah Construction Industrial Company Ltd. Seoul, Korea Project Hydropower storage project Service Provider Pöyry Energy Ltd. Services Feasibility study: • Photogrammetric and terrestrial topographic mapping • Geological investigations • Environmental impact assessment • Feasibility design • Simulation and optimisation of plant size and operation • Economic and financial analyses • Advisory services during PPA negotiations Execution Period Project Description The Xe Pian & Xe Namnoy hydropower scheme is being implemented by the client as a BOT venture with the government of People’s Democratic Republic of Laos for power exports to Thailand. The headworks of the high-head project are located on the Bolaven plateau some 500 km south-east of the capital city of Vientiane. The tailworks discharge into the Sekong river, a major Mekong tributary, at the foot of a steep, 800 m deep escarpment. The headworks consist of a diversion weir and two fill dams which are 49m and 78 m high with their appurtenances. The impounded reservoirs are inter- connected via water transfer tunnels. The 17 km long waterways comprise headrace tunnel, surge tank, vertical shaft, high pressure tunnel and open steel penstock Three Pelton units of 124 MW are installed in the open-air powerhouse. Pöyry Energy Ltd. Hardturmstrasse 161, P.O. Box, CH-8037 Zurich, Switzerland Phone: +41 44 355 55 54, Internet: www.poyry.com 1994 – 1995 Xe Pian & Xe Namnoy Hydropower Scheme Key Data Xe Pian dam Type Height Fill volume Length of crest earth-rockfill 49 m 1.1 million m3 1240 m Xe Pian reservoir Catchment area Total storage Active storage 212 km2 20 million m3 14 million m3 Xe Namnoy dam Type Height Fill volume Length of crest rockfill with core 78 m 4.6 million m3 1560 m Xe Namnoy reservoir Catchment area Total storage Active storage 533 km2 1001 million m3 907 million m3 Xe Pian river diversion Phase 1 open Phase 2 through concrete section Xe Namnoy river diversion One tunnel of Diameter Length Xe Pian spillway Three radial gates 9.5 m 462 m 10.1 m ×10 m Xe Namnoy spillway Ungated chute Crest length 45 m Water transfer conduit Xe Pian to Xe Namnoy Internal diameter Length 4.75 m 8,050 m Power waterways Pressure tunnel upper part: Ø 4.75 m, L 13,700 m (concrete) Pressure shaft: Ø 4.5 m, height 497 m (concrete) Pressure tunnel lower part: Ø 4.5 m, L 410 m (concrete) Ø 3.25/3.00 m, L 1,425 m (steel) Cut and cover steel penstock Ø 3.0 m, L 695 m Powerhouse Type Installed capacity Pelton units Design discharge Gross head Energy production at Thai border open-air 3 ×124 = 372 MW 40 m3/s 656m– 691 m 1927 GWh/year Xe Namnoy dam Project layout