【Introduction of the project】
The Nam Ngum1 Hydropower Plant is a gravity-type concrete dam located approximately 65 km north of Vientiane, the capital of Laos, and was completed in 1971 with technical assistance from Japan. In 1984, the dam was subsequently expanded into a hydropower plant equipped with five generators and a total output of 155 MW. The hydropower plant is managed and administered by Electricité Du Laos Génération (EDL-Gen) and has a large reservoir with a total storage capacity of 7 billion m3 that enables stable power generation through a seasonal adjustment effect.
The demand for electricity in Laos is growing faster than its supply, which prompted the development of a number of new and expansion projects in various forms in the country. The Nam Ngum1 Hydropower Plant Expansion Project was initially proposed in the World Bank Master Plan in 1995 and was later transferred to a Japanese ODA Project (JICA). The expansion project started the construction in 2017 under JICA and it aims to increase the power generation capacity by 40 MW through the construction of a new intake by drilling holes in the existing dam body and installation of a sixth generator.
The main features of this project were [the first piercing of an existing dam embankment in South-East Asia by installation of submersible-type temporary coffering bulkhead] and [construction of a new powerhouse in a very narrow and congested construction area adjacent to an existing powerhouse in operation]. The aforementioned aspects posed a high degree of technical difficulty and required innovative construction ingenuity.
The project was successfully completed in January 2022 without accidents or disasters, despite the challenges during the construction period including inundation of the construction yard due to an emergency discharge of water in 2018, and labor shortages and material procurement delays due to COVID-19 outbreak in 2020.