INNER SUB-PIPE APPARATUS FOR COMBINED SEWERAGE

PROBLEM TO BE SOLVED: To prevent damages to an inner sub-pipe apparatus for combined sewerage caused by a load of sewage in rainy weather while suppressing the erosion and damages to a bottom face of a manhole by allowing the sewage to directly flow into the manhole in rainy weather. SOLUTION: The inner sub-pipe apparatus 10 for the combined sewerage includes a sewage receiving part 12 formed in funnel shape opened at the upper part, and a vertical pipe part 14 formed at the lower end of the sewage receiving part 12. The sewage receiving part 12 is mounted on the basis of the pipe bottom 110 of an inflow pipe 104 connected to the manhole 100, and its upper end 20 has a height difference lower on the manhole center side by a predetermined dimension than the manhole wall surface side. The predetermined dimension of the height difference is set to lower the manhole center side upper end 20 of the sewage receiving part 12 to the maximum within a range in which the total amount of sewage in fine weather flows into the inner sub-pipe apparatus 10 for the combined sewerage. In rainy weather when the flow rate and flow velocity of sewage increase, the sewage thereby flows directly into the manhole 100 over the inner sub-pipe apparatus 10 for the combined sewerage while hardly colliding against the pipe wall of the inner sub-pipe apparatus 10 for the combined sewerage. COPYRIGHT: (C)2011,JPO&INPIT