Sub-grade

From LID SWM Planning and Design Guide
Revision as of 18:48, 3 August 2022 by Kyle menken (talk | contribs) (Created page with "The term “sub-grade” refers to the excavated bottom of native soils that forms the bottom of a ground-level LID practice. Excavation to the subgrade will differ depending on whether the design is for an infiltrating or a non-infiltrating LID system. If it’s an infiltrating practice, the sub-grade should be as level as possible to promote even infiltration across the facility’s footprint. For non-infiltrating practices, excavate sub-grade slopes to the design gra...")
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The term “sub-grade” refers to the excavated bottom of native soils that forms the bottom of a ground-level LID practice. Excavation to the subgrade will differ depending on whether the design is for an infiltrating or a non-infiltrating LID system. If it’s an infiltrating practice, the sub-grade should be as level as possible to promote even infiltration across the facility’s footprint. For non-infiltrating practices, excavate sub-grade slopes to the design grade in the direction of the underdrain, typically 1 to 5 %. As with all infiltrating LID practices, avoid compaction of sub-grade soils whenever possible. However, depending on the design and the local municipality, compaction of the sub-grade may be required.