Many regions have turned to low impact development technologies (LIDs), which are implemented to restore the changes in stormwater runoff that have resulted from urbanization. Green roofs are one typical type of LID. Until now, many studies have validated their roles in managing urban stormwater runoff. However, they have also revealed that the performance of green roofs largely varies with their design configuration, as well as their hydro-climatic exposure. The objectives of this review paper are to statistically synthesize the effects of the influential factors, including design and hydrologic variables, on green roof performance and to explore their effects in different climatic zones. The review’s results confirm the differences in the influential variables and, thus, the performance of green roofs in different climatic zones. These are the barriers to knowledge translation among engineering designers, stormwater managers, and policymakers in different climatic zones when implementing green roofs. Consequently, region- or site-specific studies are necessary to implement green roofs with confidence.

This paper examined and compared the hydraulic and environmental performance of permeable interlocking pavers (PICPs), porous asphalt (PA), and porous concrete (PC) under cold climate conditions in Calgary, Alberta, Canada. Assessments were made of their hydraulic performance in terms of storm runoff reduction and surface infiltration capacity, and environmental performance in terms of the removal of several pollutants including total suspended solids (TSS), total nitrogen (TN), total phosphorous (TP) and, heavy metals: copper (Cu), lead (Pb), and zinc (Zn). Results from this paper demonstrated that PA, PC, and PICPs are all effective in mitigating storm runoff under cold climate conditions. Surface infiltration rate was substantially affected by winter sanding materials for PA, PC, and PICPs. Pressure washing was demonstrated to be able to partially restore surface infiltration rates for all three types of pavements. All pavement types in general have the same level of performance in removing TSS, TP, TN, and heavy metals. The removal of TSS, TP, and heavy metals appears to be independent of climatic conditions, whereas TN removal tends to decline with a decrease in pavement temperature.

This study examined the effectiveness of open-joint inter-locking pavers in a permeable pavement in cold (winter) conditions. A field-scale inter-locking paver cell (UNI Eco-Optiloc^®) was built to evaluate the hydraulic performance and water quality improvements experienced during freeze-thaw and frozen conditions in Calgary, Alberta, Canada. Hydraulic performance was assessed using stormwater runoff reduction (peaks and volumes) and surface infiltration capacity. Water quality performance for removal of total suspended solids (TSS), total nitrogen (TN), total phosphorous (TP) and three heavy metals: copper, lead and zinc, was assessed. Results from the study demonstrated that the inter-locking pavers were effective in attenuating stormwater runoff peak volumes. The surface infiltration capacity decreased significantly due to the deposition of sanding and de-icing materials on the pavement surface during winter operation. Infiltrated stormwater was stored and treated within the pavement structure, which showed removal rates of 91% for TSS, 78% for TP, 6% for TN, 68% for zinc, 69% for copper and 55% for lead.