This table shows guidance on BMP selection based on physical feasibility characteristics of a site.
Link to this table.
|BMP group||Surface areaa||Drainage area||Soil infiltration rate||Head||Separation from bedrock||Depth to seasonally high water table||Maximum slopec||Ultra-urban|
|Bioretention||7-10%; Minimum 200 ft2||5 acre maximum; 0.5-2.0 acre preferred||Any soil; use underdrain for C and D soilsd||3 feet||3 feet||20%||Yes|
|Filtration - media||Negligible, except for access||5 acre maximum; 0.5-2.0 acre preferred||Media part of designd||2-6 feet||0 feet if enclosed||3 feet for vegetated; 0 feet if enclosed||20%||Yes|
|Filtration - vegetative||Varies based on depth||10 acre maximum||Media part of design||2-6 feet||0 feet if enclosed||3 feet for vegetated; 0 feet if enclosed||20%||Possible|
|Infiltration trench||Varies based on depth||5 to 10 acre maximum||Native soils with i >= 0.2 inches/hour||2-12 feet||3 feet||3 feet||15%||Possible|
|Infiltration basin||Varies based on depth||5 to 50 acre maximum||Native soils with i >= 0.2 inches/hour||2-12 feet||3 feet||3 feet||15%||No|
|Stormwater ponds||1-3%||10 to 25 acres recommendedb||A or B soils may require liner||3-10 feet||0 feet (shallow soil limits design)||0 feet (except if hotspot or aquifer)||25%||No|
|Constructed wetlands||2-4%||25 acre minimumb||A or B soils may require liner||3-10 feet||0 feet||0 feet (except if hotspot or aquifer)||25%||No|
aSurface area as a function of contributing surface area, except for ponds and wetlands, where it is a function of entire drainage area
b10 acres or less may be feasible if groundwater is intercepted and/or if water balance calculations indicate a wet pool can be sustained
cSlope is defined as the slope across the proposed location of the practice
dInfiltration gallery could be designed to provide limited recharge