| 摘要 |
PROBLEM TO BE SOLVED: To eliminate bothersome work such as cutting of pavement, excavation, and back-filling, which has been conventionally executed when a cap is connected to a pipe line in order to prevent a foreign matter from entering the pipe line. SOLUTION: There is provided an inner cover for a downstream pipe in a drainage basin, which is formed by opening a cover for an upper portion of the drainage basin and arranging the inner cover into the downstream pipe.
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