Visit to Plant

5MW Solar Plant Built on 26-degree Sloping Dam Wall (page 3)

Slope specialists hired for construction

2016/06/21 15:21
Shinichi Kato, Nikkei BP CleanTech Institute
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Slope specialists

The length of the dam body slope is about 150m (about 50m at both Gongen Dam and Heiso Dam). The height is about 80m (about 33m at Gongen Dam and 26m at Heiso Dam), and the average pitch is about 26° (about 22° on average at both Gongen Dam and Heiso Dam). Sloping more (Fig. 5) and being longer, it was more difficult to set up solar panels on this site.

Fig. 5: The average 26-degree slopes give the impression of slopes used by advanced-level skiers. (source: top Novac, bottom Nikkei BP)

As I walked around the body of Kotani Dam when I visited for an interview, I got the impression I was walking on slopes for advanced-level skiers.

Based on these conditions, construction staff called "slope workers," who are proficient in working on sides and other slopes, were hired (Fig. 6). During the peak construction period, approximately 100 workers were engaged in construction on the slopes each day.

Fig. 6: Construction staff trained for working on slopes were used. Novac also took all possible safety measures, for example by selecting the staff's shoes and keeping them from working while the slopes were wet. (source: Novac)

At Kotani Dam, where the length of the slopes is as long as about 150m, a monorail for construction work was used (Fig. 7). Laying tracks on completed foundations along the stairs that had originally been set up for dam body inspection and other purposes, the plant operated monorails from the top to the bottom of the dam body so they could transport heavy loads. Monorails were laid along the stairs that had been built on both sides of the dam body.

Fig. 7: Heavy loads were transported by a monorail for construction work. Because of the slopes being as long as about 150m, cranes could not be used for transporting heavy loads in some areas. (source: Novac)