Changes

*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.

*In the conceptual design stage it is recommended to reserve approximately 10 to 20% of the contributing drainage area for the bioretention facility footprint.

*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 recommended ratios of impervious drainage area to pervious facility footprint area (I:P area ratio) range from 5:1 on low permeability soils (HSG C and D) to 20:1 on high permeability soils (HSG A and B).

*For optimal performance recommended ratios of impervious drainage area to pervious facility footprint area (I:P area ratio) range from 5:1 to 15:1 on low permeability soils (HSG C and D) and 10:1 to 20:1 on high permeability soils (HSG A and B).

*Minimum bioretention facility footprint area (i.e., filter bed area) is based on the design storm runoff volume and effective surface ponding depth.

*Minimum bioretention facility footprint area (i.e., filter bed area) is based on the design storm runoff volume and effective surface ponding depth.

*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.  

==Inspection and Maintenance==

==Inspection and Maintenance==

Bioretention requires regular, routine inspection and maintenance of the landscaping as well as periodic inspection of other parts of the facility. Routine maintenance should include weeding, pruning, and mulching, similar to other landscaped areas, as well as the removal of trash, debris and sediment accumulated in pretreatment areas, inlets and outlets. Watering may be needed until plant establishment (first 2 years). <br>

Bioretention requires regular, routine inspection and maintenance of the landscaping as well as periodic inspection of other parts of the facility. Routine maintenance should include weeding, pruning, and mulching, similar to other landscaped areas, as well as the removal of trash, debris and sediment accumulated in pretreatment areas, inlets and outlets. Watering may be needed until plant establishment (first 2 years). Periodic replacement of the top 5 cm of filter media around inlets (e.g., every 5 to 10 years) will help maintain treatment performance.<br>

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Inspections should occur twice annually (spring and late fall) and after major storm events. Inspect for vegetation density (≥ 80% coverage), damage by foot or vehicle traffic, erosion, debris and sediment accumulation, and damage to pretreatment devices.<br>

Inspections should occur twice annually (spring and late fall) and after major storm events. Inspect for vegetation density (≥ 80% coverage), damage by foot or vehicle traffic, erosion, debris and sediment accumulation, and damage to pretreatment devices.<br>

Cleanouts and access points should be provided to allow clean-out of the underdrain and overflow pipe. Camera inspection of these pipes should be conducted every 5 years to ensure pipes are free of roots, sediment and debris. Hydraulic flushing or root removal may be needed to clear debris or obstructions.

Cleanouts and access points should be provided to allow clean-out of the underdrain and overflow pipe. Camera inspection of these pipes should be conducted every 5 years to ensure pipes are free of roots, sediment and debris. Hydraulic flushing or root removal may be needed to clear debris or obstructions.