Hitachi, Ltd.

Yutaka Shimada

Seiji Miura

Sadashi Tanaka

Kunio Takada

Masayuki Yamada

Akira Manabe

In a drainage pump station, a driving machine has a capacity greater than a shaft power necessary for no-discharge operation of a pump, and during severe flooding the pump is operated at an overload exceeding its design capacity. During maintenance operation water is fed from a river on the delivery side of the pump station into the station. When an inflow of rainwater into the pump station is great the pump is operated at the necessary capacity, when it becomes small the water level is kept above a rated value, and when the inflow rate is zero the pump discharge is increased to a capacity at which sediment can be discharged. A suction blower is disposed at the top of a suction sump and interstage valves are disposed in entrances of vertical shafts to effect efficient ventilation of the underground waterway. A feed channel is operated as a pressure channel and the pump is of variable capacity and the water level in the underground waterway is controlled to be constant.

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Ibaraki-ken, Japan

Yutaka Shimada