456 - Permeable Pavement Subsurface Temperature Properties: Implications for Deicer Reduction

Permeable pavement (PP) has been shown to be an effective urban stormwater management tool, reducing stormwater peak flows, volumes, and sediment-associated pollutants entrained in runoff. Although PP appears to provide little treatment for dissolved ions, such as chloride, some water quality benefits may be realized in cold-weather climates where deicers are the primary form of treatment for snow and ice. Studies have suggested 50% to 100% less deicer is needed for PP than impervious surfaces to perform at similar levels.
Seven years of sub-surface temperature data from permeable interlocking concrete pavers (PICP), pervious concrete (PC), and porous asphalt (PA) were evaluated. Temperature profiles showed subsurface temperatures remained above freezing, even when air temperature was below freezing. This thermal lag, combined with the porous nature of PP, produced favorable conditions for rain and snowmelt infiltration during winter months while limiting surface ice formation. Air spaces also act as an insulator, delaying and reducing the depth of frost compared to impermeable surfaces. PICP outperformed PC and PA with fewer days below freezing, higher temperatures on melt days, slower freeze and faster thaw times, and less penetration of freezing temperatures at depth. This study builds on an ongoing body of evidence that can be used to inform environmental managers about freeze-thaw responses of PP and the implications for the reduction of deicers in cold-weather climates.