Seasonal Performance Variations for Storm-Water Management Systems in Cold Climate Conditions

Lack of widespread adoption of low-impact development (LID) designs in northern climates is in large part due to concerns about poor winter performance relating to (1) frozen filter media; and (2) dormant biological functions. An examination of six varied LID designs, in contrast with conventional best-management practices (BMPs) and manufactured systems illustrated that seasonal functionality was evident for many systems; however, the LID designs were consistently top storm water management performers. The designs were tested and monitored for cold climate performance from 2004-2006 to assess: filter media frost penetration, hydraulic efficiency, and seasonal variations of contaminant removal efficiency. LID systems evaluated included: two types of bioretention systems, a surface sand filter, a subsurface gravel wetland, a street tree, and porous asphalt. The LID performance data were contrasted with conventional structural BMPs (swales, retention pond) and some select manufactured storm-water systems (hydrodynamic separators); (3) a filtration system, and a subsurface infiltration system. Seasonal performance evaluations indicate that LID filtration designs differ minimally from summer to winter, while smaller systems dependent largely on particle settling time demonstrated a marked winter performance decline.