PURPOSE: To improve functionability by having the first passage to connect the first drain port to a drain chamber and a filter section, a screen section, and the filter section and the drain chamber, and the second passage to connect the screen section to the drain chamber.
CONSTITUTION: An ordinary rainfall flows from a flow-in section into a regulating pondage after eart and sand are removed in a filter section 17, flows through the first passage 29 into a drain chamber 15, and passes through the first drain port 7 and discharges from the first drainage canal 11, and the earth and sand are piled up in an earth and sand piling up section 1701. When water quantity flowing from the flow-in section increase further, water from which the flowing water is removed by a screen section 19 passes through the second passage 31 into a drain chamber 15, and passes through the first drain port 7 and discharges from the first drainage canal 11. When the quantity of rainfall at the time of a heavy rain becomes more than the water quantity discharged from the drainage canal 11, the water is gradually stored in the reservoir, and the quantity of drainage is restricted. When the quantity of stored water exceeds water storing limit determined by height H2 from the bottom of the reservoir 1 to the top of an overflow weir 1303, the water passes from the second drainage port 9 through the second drainage canal 13 and discharges.
TSUCHIYA HIROAKI
OKUDA TAKAO
TSURUMI CONCRETE KK
KEIHAN CONCRETE KOGYO KK