1. French drain closed conduit covered gutter blind drainage subdrain...
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2. Provided that no covered drain shall have an internal diameter of less than 100 mm.
但任何暗置排水渠的内径不得少于100毫米。
3. If half of your landscaped areas are paved or covered with nonporous materials, precipitation will drain to other to drain to planted soil areas.
如果您的花木种植区一半的道路，或与无孔材料覆盖，降水将流失到其他排的种植面积的土壤。