Summary of Bioretention Variants for Permeability of Native Soils and Potential Land use Pollutant Loading
(Link to this table)

Bioretention Type Variant Underlying Soil Performance Criteria
Bioinfiltration
(Infiltration/Recharge Facility)
No underdrain Higher recharge potential (facility drain time without underdrain is 48 hours or less)
Biofiltration with underdrain at the bottom
(Filtration/Partial Recharge Facility)
Underdrain Lower recharge potential (facility drain time without underdrain is > 48 hours)
Biofiltration with internal water storage underdrain Lower recharge potential (facility drain time without underdrain is >48 hours)
Biofiltration with elevated underdrain
(Infiltration/Filtration/Recharge Facility)
Elevated underdrain Higher nutrient loadings and/or quantity control
Biofiltration with liner
(Filtration Only Facility)
Underdrain with liner Hot Spot Treatment