STAFF INTERVIEW
Director of Shin-Maruyama Dam JV Construction Office
Keiji Sasaki
Maruyama Dam construction started in 1943 (Showa 18) and then it was interrupted due to the war, and it was completed in 1956 (Showa 31). It is the first 100m class-height dam in Japan. Therefore, it was decided to construct the Shin-Maruyama Dam, which is 20.2m heightened than the current and has a flood control storage of 3.6 times more than before, at a point 47.5m downstream of the Maruyama Dam. This is the largest heightening of dam construction work in Japan.
Normally, river flow is diverted, and the dam is constructed, but this time it is a renovation construction work while operating the existing dam. We will work in a two-step process, first, constructing the dam body from the left bank, and connecting it to the Maruyama Dam with a bulkhead so that it can be operated, and then advancing construction work on the right bank.
We always consider the possibility of disaster occurrence related to torrential rain and floods as we advance with the construction work while maintaining the functions of Maruyama Dam located on the Kiso River of large river. Therefore, it is necessary to constantly monitor the weather in the upstream area and information on dam discharge and decide whether to continue or stop the work. Care shall be taken not to impair the function of the existing dam during excavation and blasting.
In addition, it is important to harmonize with the local community without violating the living environment of local people in the vicinity of the dam construction site. To gain an understanding of the residents, we always visualize the construction status and developing technology and communication is done in an easy-to-understand manner.
I was taken part in the construction of the San Vicente Dam in San Diego, USA before. Like the Shin-Maruyama Dam construction work, the existing dam was raised, but as it was a dam to store water for daily uses, there was little danger of flooding, so I think the Shin-Maruyama Dam is a highly difficult construction. However, as points to keep in mind are common in terms of construction and quality control for raising construction, so I would like to make use of the experience I have accumulated in this construction.
The time we confirm the dams that were constructed in the past can store water well and are useful for the lives of the local people, we will be rewarded for all our hard work. There are many difficulties during involvement with the dam construction, but it is also a great rewarding job.
Shin-Maruyama Dam is a multi-purpose dam to be constructed on the border of Yaotsu Town, Kamo County, Gifu Prefecture, and Mitake Town, Kani County, on the Kiso River in the Kiso River system.
This is a renovation of an existing dam project to construct a 20.2m heightening than the current at a position 47.5m downstream of the existing Maruyama Dam to improve power generation and flood control functions
Construction title: 2020 Shin-Maruyama Dam body construction first phase
Client: MLIT Chubu Regional Development Bureau Shin-Maruyama Dam Construction Office
Construction site:（Right bank）Yaotsu area, Yaotsu-cho, Kamo-gun, Gifu Pref （Left bank）Kowasawa area, Mitake-cho, Kani-gun, Gifu Pref.
Construction period: Jan. 29, 2021 to Mar. 31, 2025 * Construction period for the first phase of construction only.
Contractor: Obayashi, Oomoto, Ichikawa special construction consortium
Dam type: Gravity concrete dam（dam height 118.4m, crown length 340.3m）
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