Sustainability-Based Construction of the Restoration Projects for the Guguan Hydropower Station

In Taiwan, the Dajia River is one of the most important rivers that provides hydroelectric energy. A couple of well-operated hydropower stations have been placed in different sections of this river for several decades. The 921 earthquake that hit central Taiwan in 2000 and Typhoon Toraji that attacked this area in 2001 caused severe damage to almost all hydropower stations. To continue to provide sufficient power for the public, the restoration of these power stations is necessary. Taiwan Power Company (Taipower) was responsible for the restoration projects. The Guguan hydropower station, which could provide 212.8 MW power, is one of the most damaged power stations. The Guguan power station restoration project, executed by the New Asia Construction and Development Corporation (NA Corp.), was started in April 2002. During the project, a series of typhoons and heavy storms attacked central Taiwan between 2004 and 2007 (especially Typhoon Mindulle in 2004). Consequently, the restoration work was greatly hindered; in particular, there was massive groundwater leakage from all external walls of the tunnel and powerhouse structures. The maximum leakage of groundwater was up to 84 tons/min. This situation not only caused extreme difficulty that interrupted the restoration work but also made the construction site a dangerous environment to continue restoration or future operation. In addition, the construction facilities were damaged, resulting in suspension of the restoration work. For safety construction of the restoration work, a series of temporary protection structures/platforms and a large quantity of grouting work had been performed. This power station was well restored and engaged in commercial operation in October 2008. In this paper, the detailed working procedures of the safety construction methods are presented. (paper)