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Line 104: − + − *In the conceptual design stage it is recommended to set aside approximately 10 - 20 % of the contributing drainage area for bioretention facility placement. Line 114:
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→Available Space
===Available Space===
===Available Space===
*Reserve open space equal to roughly 10 to 20% the size of the contributing drainage area.
*In the conceptual design stage it is recommended to reserve approximately 10 to 20% of the contributing drainage area for the bioretention facility footprint.
*For optimal performance bioretention facilities should receive runoff from impervious drainage areas between 5 to 20 times their own permeable footprint surface area.
*For optimal performance bioretention facilities should receive runoff from impervious drainage areas between 5 to 20 times their own permeable footprint surface area.
*Bioretention cells work best when distributed, so that no one facility receives runoff from more than 0.8 Ha, although there is a trade off to be considered regarding distributed collection and treatment versus ease of maintenance.
*Bioretention cells work best when distributed, so that no one facility receives runoff from more than 0.8 Ha, although there is a trade off to be considered regarding distributed collection and treatment versus ease of maintenance.
*Bioretention can be almost any shape, from having very curvilinear, soft edges with variable depth, to angular, hard-sided and uniform depth.
*Bioretention can be almost any shape, from having very curvilinear, soft edges with variable depth, to angular, hard-sided and uniform depth.
*Proximity to underground utilities and overhead wires: Consult with local utility companies regarding horizontal and vertical clearance required between storm drains, ditches, and surface water bodies. Further, check whether the future tree canopy height in the bioretention area will not interfere with existing overhead wires.
*Proximity to underground utilities and overhead wires: Consult with local utility companies regarding horizontal and vertical clearance required between storm drains, ditches, and surface water bodies. Further, check whether the future tree canopy height in the bioretention area will not interfere with existing overhead wires.
The principles of bioretention can be applied in any scenario where planting or vegetation would normally be found.
The principles of bioretention can be applied in any scenario where planting or vegetation would normally be found.
===Site Topography===
===Site Topography===
Contributing slopes should be 1 to 5%. The filter bed surface should be flat to allow flow to spread out. A stepped, multi-cell design can also be used.
Contributing slopes should be 1 to 5%. The filter bed surface should be flat to allow flow to spread out. A stepped, multi-cell design can also be used.