| 摘要 |
PROBLEM TO BE SOLVED: To provide a lid device for covering a side ditch capable of maintaining a high efficiency of permeability over a long period of time and of maintaining a good appearance. SOLUTION: A dish-shaped permeable grating 9 having a grid portion 14 at the bottom surface is installed at the upper opening portion of the side ditch 1, and many small natural stones 16 are roughly filled in the permeable grating 9 in a fluid and unbonded state.
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