Low Impact Development Manual for Michigan - OSEH - University ...

Key Design Features
• Depth to water table or bedrock
• Pretreatment is often needed to prevent clogging
• Often requires level infiltration surface
• Proximity to buildings, drinking water supplies,
karst features, and other sensitive areas
• Soil types
• Provide positive overflow in most uses
Site Factors
• Maximum Site Slope: 20 percent
• Minimum depth to bedrock: Two feet
• Minimum depth to seasonally high water table: Two
feet
• Potential Hotspots: Yes with pretreatment and/or
impervious liner
• NRCS Soil type: A, B, C*, D*
*C & D soils have limited infiltration ability and may
require an underdrain.
Infiltration BMP Max. Drainage Area
Berming 5 acres
Dry Well 1 acre
Infiltration Basin 10 acres
Infiltration Trench 2 acres
Subsurface Infiltration Bed 5 acres
Benefits
• Reduces volume of stormwater runoff
• Reduces peak rate runoff
• Increases groundwater recharge
• Provides thermal benefits
Limitations
• Pretreatment requirements to prevent clogging
• Not recommended for areas with steep slopes
Erosion control matting and rock can be used at surface
flow entrances
Bioretention is one variation of an infiltration BMP, such as
this rain garden at the Macomb County Public Works Building
LID Manual for Michigan – Chapter 7 Page 194