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

BMP Fact Sheet Variations
• Inflow
Level Spreaders
Level spreaders promote infiltration and improve water quality by evenly
distributing flows over a stabilized, vegetated surface. This allows for
better infiltration and treatment. There are several different types of level
spreaders. Examples include concrete sills, earthen berms, and level perforated
pipes.
LaVista Storm Drain Project Level Spreader
Source: City of Battle Creek
Applications Stormwater Quantity Functions
Residential Yes Volume Low
Commercial Yes
Groundwater
Recharge
• Outflow
Key Design
Features
• Ultimate outlet from structural
BMPs
• Roof downspout connections
(roof area > 500sf)
• Inlet connections
(impervious area > 500sf)
• Inflow to structural BMP, such
as filter strip, infiltration basin,
vegetated swale
Site Factors
• Water table to bedrock
depth – N/A
• Soils – Permeability not critical
but should be considered
for erodibility
• Slope – 1-8 percent max.
• Potential hotspots – Yes
• Maximum drainage area –
Varies (five acres max.)
Benefits
• Low cost
• Wide applicability
• Ability to work with other
BMPs in a treatment train
• Avoids concentrated discharges
and their associated potential
erosion
Limitations
• Low stormwater benefits
by itself
• Careful design and construction
required to function properly
LID Manual for Michigan – Chapter 7 Page 221
Low
Ultra Urban No Peak Rate Low
Industrial Yes Stormwater Quality Functions
Retrofit Yes TSS Low
Highway/Road Yes TP Low
Recreational Yes
NO3
Low
Temperature Low
Additional Considerations
Cost Low
Maintenance Low
Winter Performance High