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

In general, the techniques described in this manual can
be used very effectively in cold climate settings such
as Michigan (when the appropriate recommendations
are followed). In addition, LID encourages stormwater
management systems and treatment trains that can offer
increased resiliency for cold climate issues.
Critical aspects of winter conditions are extremely cold
temperatures, sustained cold periods, and polluted snowmelt,
as well as a short growing season (Table 7.2).
Extreme cold can cause rapid freezing and burst pipes.
Sustained cold can result in development of thick ice or
frozen soil layers in some BMPs. On the other hand,
the deeper and more persistent the snow layer, the
less severe the soil freezing. Water quality problems
associated with snow melt occur because of the large
volume of water released during rain and snow events.
This runoff carries material that has accumulated in the
snowpack all winter, as well as material it picks up as it
flows over the land’s surface.
Chloride is the cause of many problems associated with
snowmelt runoff. Chloride is a very soluble chemical
that migrates easily through treatment systems and
soil. Avoiding over-application of chloride, and routing
runoff properly are effective ways to reduce damage to
LID BMPs.
Table 7.2
Cold Climate Design Challenges
Climactic Condition BMP Design Challenge
Cold Temperatures
Deep Frost Line
Short Growing Season
Significant Snowfall
• Pipe freezing
• Permanent pool ice cover
• Reduced biological activity
• Reduced oxygen levels during ice cover
• Reduced settling velocities
• Frost heaving
• Reduced soil infiltration
• Pipe freezing
General considerations
Avoid pipe freezing by laying pipes and installing
underground systems below the typical frost line. Pipe
freezing for standpipes is not likely to be an issue, but
conveyance pipes laid nearly horizontal should be
below the freezing line. In Michigan, most communities
plant at least a foot or two of groundcover over
stormwater pipes to minimize the risk of pipe freezing.
Over-excavation and filling with sand and gravel around
stormwater pipes will also help with frost penetration
and frost heave.
Figure 7.2
Chloride damaged white pines
• Short time period to establish vegetation
• Different plant species appropriate to cold climates than moderate climates
• High runoff volumes during snowmelt and rain-on-snow
• High pollutant loads during spring melt
• Other impacts of road salt/deicers
• Snow management may affect BMP storage
Source: Michigan State University Extension
LID Manual for Michigan – Chapter 7 Page 126