The Project is located on the Nam Ngiep River, a tributary of the Mekong River (MAP 1). The river joins the Mekong at Pakxan which is located about 150 km away from Vientiane Capital. The Nam Ngiep River originates in Xiang Khouang Province and runs about 160 km before joining the Mekong, 1,300 m lower in elevation. The Project area stretch from Bolikhamxay Province to Vientiane Province, the main dam, re-regulation dam and powerhouse are located in Bolikhan District, Bolikhamxay Province while major part of the reservoir area belongs to Hom District, Vientiane Province.
Nam Ngiep 1 is a 290-megawatt hydropower project under construction in Bolikhamxay and Xaysomboun provinces of the Lao PDR. The project is being built and will be operated by the Nam Ngiep 1 Power Company Limited, whose goal is to build a socially and environmentally responsible power project that will provide clean renewable electricity and contribute to poverty reduction in Laos.
NNP1 is working with local people and authorities to build high-quality new houses and community facilities for the villagers moving to the Houaysoup area, The Company is also developing a range of livelihood programmes for people directly affected by the project.
Environmental protection is also crucial to the long-term success of the project and NNP1 has created a dedicated Environmental Management Office to ensure that the project minimizes its local footprint and also contributes to improved conservation measures and environmental awareness on a national scale.
What is now known as the Nam Ngiep 1 Hydropower Project was identified in the early 1990s and a preliminary feasibility study conducted in 1991. The Lao government’s agreements with the Project’s initial developers expired and in 1996 the government requested the Japan International Cooperation Agency (JICA) to conduct a full feasibility study into social and environmental impacts and technical and commercial aspects.
The JICA study, conducted over two phases from 1998-2000 and from 2001-2002, confirmed the Project’s technical feasibility on a build-operate-transfer basis and made recommendations for its optimal development based on physical, economic and environmental and social safeguard considerations.
Japan’s Kansai Electric Power Company joined other interested Japanese partners on further studies in May 2003, and in April 2006 signed a project development agreement with the government. A year later Kansai and the Electricity Generating Authority of Thailand (EGAT) entered an agreement to develop the Project. Consultations with people living in the project area continued alongside technical studies on topography and geology. On the legal development side, a revised memorandum of understanding on tariffs was concluded in July 2011 and a power purchase agreement signed in 2013.
In late 2013 and early 2014 preparations for construction began, with the planning of the access road. As agreements were reached with local people and authorities, work began on the road while discussions continued on how best to arrange resettlement and compensation for all people affected by the Project. In May 2014 national-level consultations involving villagers, local officials, senior politicians, the project developers and financial backers, followed village, district and provincial level meetings. In September that year financial close was reached as the nine banks backing the project reached agreement on fiscal and legal terms, paving the way for full construction to commence.
The Project has a gravity dam by means of RCC construction method, which creates about 70 km long reservoir. Reservoir water will be used by two units of turbine at the powerhouse located on immediate downstream of the main dam. The general layout of the main dam is shown in Figure 2. The facilities around the main dam are composed of one lane of river diversion tunnel, a gated spillway, an intake structure and penstock, a surface type powerhouse, outlet facilities, related accessory equipment, etc. The dam is 167 m high and 530 m crest length and the total volume is around 2.3 MCM. Further, the re-regulation dam is installed at 5 km downstream from the main dam to release the 16-hour peaking inflow from the main dam evenly on a 24-hour basis. The river water will be diverted by one diversion tunnel driven through the left abutment, together with two cofferdams to be installed at the upstream and downstream sides of the main dam. After completion of its function as river diversion the tunnel will be permanently plugged with concrete.
The spillway is a gated overflow structure on the main dam. Maximum outflow equivalent to 1,000-year flood can be discharged through the spillway at Flood Water Level.
Power intakes, intake gates and penstocks are installed in the main dam body. The powerhouse will be located at the downstream of the main dam, semi-underground type of power house.
Transmission lines of the Project will be comprised of a double-circuit 230 kV line for the electricity exportation to Thailand and a single-circuit 115 kV line for the domestic electricity supply (Figure 1). The 230 kV transmission line will be from Nam Ngiep (Main Dam Switchyard) to Nabong substation. The length of the transmission line is approximately 130 km. The 115 kV transmis sion line will be from Nam Ngiep (Re-regulation Dam Switchyard) to the existing Pakxan Substation. The length of the transmission line is approximately 40 km.