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→Design
==Design==
==Design==
===Geometry and Site Layout===
Infiltration chambers and soakaways can be designed in a variety of shapes, although facilities should have level or nearly level bottoms to spread flow evenly throughout. Typically designed with an impervious drainage area to pervious facility footprint area ratio (i.e. I:P ratio) between 5:1 on low permeability soils (HSG C & D) to 20:1 on high permeability soils (HSG A & B). Not typically deeper than 4 m.
===Inlets===
Recommended to distribute inflow between multiple inlets to reduce risk of failure. May include delivery of runoff to the facility as concentrated overland or concentrated underground (i.e. pipe) flow.
For concentrated overland flow:
*(i) Draining roads Catch basins or other inlet structures should be located at all sag points in the gutter grade and immediately upgrade of median breaks, crosswalks and street intersections,
*(ii) Inlet types include curb openings, side inlet catch basins, trench drains, and other pre-fabricated inlet structures,
*(iii) Spillways aid in turning flow 30, 45 or 90 degrees into the practice,
*(iv) If the inlet structure itself does not provide sedimentation or filtration pre-treatment, incorporate a pre-treatment gravel diaphragms geotextile and stone filter inlet at curb opening or spillway locations to isolate sediment, trash and debris for ease of removal, and
*(v) Provide provide a 50 to 100 mm drop in elevation between inlet invert and top elevation of the gravel diaphragmpre-treatment practicestone cover.
===Sizing===
===Sizing===
[[Infiltration: Sizing and modeling]]
[[Infiltration: Sizing and modeling]]