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 feet0 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

This page was last edited on 3 October 2019, at 17:49.

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