The Naruse Dam, currently under construction by the national government in Higashi-Naruse Village, Akita Prefecture, is due for completion in three and a half years, and the largest trapezoidal CSG dam in Japan has been revealed. Its height is the height of a 30-story apartment building, and its length is roughly equivalent to the distance between Tokyo Station and Yurakucho Station. Meanwhile, the dam construction tours, which are popular in the Tokyo metropolitan area, have drawn the attention of young people to the village, and the “Naruse Dam Sri Lankan curry” taught by a Sri Lankan worker has also become popular, making Japan’s largest dam already a contributing factor to the revitalization of the region.
The cross section is a pyramid
The bus passed a super-large 50-ton dump truck as it descended the construction road toward the bottom of the valley of the Naruse River, which originates from Mount Kurikoma (1,626 meters) that straddles the three prefectures of Iwate, Miyagi, and Akita. The Naruse Dam Construction Office of the Ministry of Land, Infrastructure, Transport, and Tourism held a press release on July 12.
Looking up from the valley floor upstream of the dam, the embankment is 96 meters high and 755 meters long. Its grey surface is exposed against the summer sky, blocking out the entire valley with its overwhelming size.
CSG stands for cemented sand and gravel, and will use local gravel and crushed stone. “CSG will be poured 25 centimeters thick, with three layers per step, and stacked so that the cross section is trapezoidal. Pouring will be completed in about 150 steps before winter,” said Tsuyoshi Abe, director of the office. The final height will be 114.5 meters. The surface of the cross section is stepped, just like the pyramids of Egypt.
DX at construction sites
Kajima Construction, which is in charge of the construction, and other companies are boldly promoting digital transformation (DX). For the construction of the embankment, 14 heavy machinery are operated 24 hours a day by remote control by just three operators. The grain size measurement of CSG sand and gravel is being carried out using AI, and the progress management of crushed stone extraction is being dramatically reduced by using 3D modeling of drone photography.
Preliminary surveys for Naruse Dam began in 1983, and after the relocation of the national highway that was submerged in the dam lake and the damming of the river, construction of the dam itself began in 2018. The total project cost is approximately 260 billion yen, and it is the largest trapezoidal CSG dam in Japan in terms of height, length, volume, and total water storage capacity of 78.5 million cubic meters.
In addition to regulating floods and maintaining flow rates, the irrigation system will irrigate approximately 10,000 hectares of farmland in the central-southern Yokote Basin, enabling the intake of up to approximately 13,000 cubic meters of water for drinking water use per day.
The power plant that the prefecture will build downstream of the dam will be able to supply electricity for 7,400 households. This hydroelectric power plant will not be dedicated to generating electricity, but will also be used to maintain flow, and for water supply and irrigation.
Interested by young people and women
The office holds public tours of the advanced construction work several times each month between May and October, and last year about 1,200 people participated, including from the Tokyo metropolitan area.
A 19-year-old employee from the same office, originally from Akita City, was so impressed by the tour that he started working at the Tohoku Regional Development Bureau last spring. A man who graduated from the University of Tokyo this spring was also fascinated by the cutting-edge technology in the dam’s construction, so he joined the Ministry of Land, Infrastructure, Transport and Tourism and was assigned to the same office.
Digital transformation has dramatically changed the image of the construction industry, leading to a sharp increase in visits by schools and women’s professional organizations, and construction sites are now being used for human resource development as well.
Sri Lankan Connection
As of June, there were 774 construction workers, of which 109 were foreigners from Asia, with Sri Lankans making up the largest proportion at any one time, at 84.
“The village’s food and beverage businesses learned the recipe from them and developed it,” said Tomoya Ishikawa, secretary general of the village’s chamber of commerce, about the “Naruse Dam Sri Lankan Curry.” A 100-gram retort pack costs 540 yen.
“Even though we make it less spicy than the original, it’s still quite hot and spicy. It’s become known nationwide in the two years since its release, and we’re considering making a second specialty product. The Naruse Dam has been very helpful in developing new industrial areas for the village, such as tourism and hospitality,” Ishikawa confides.
Deputy Mayor Tanito Noboru said, “Our village’s population is the only one in the prefecture that has increased due to the dam construction, but it will decrease once it is completed. However, the dam, which is the largest in Japan and utilizes cutting-edge technology, has changed the image of our village and has attracted the attention of young people. I hope that the new dam lake will also have an endearing name, which will lead to the revitalization of the village.” (Yanamami Tomomasa)
Source: Japanese