Water Quality and Hydrologic Performance of a Porous Asphalt Pavement as a Storm-Water Treatment Strategy in a Cold Climate

This study examined the functionality of a porous pavement storm-water management system in coastal New Hampshire where 6 months of subfreezing temperatures typically occur. The usage of porous pavements for storm-water management in northern climates has many challenges, most of which relate to the extreme cold and significant frost penetration into the porous media. The porous pavement system was monitored for hydraulic and water-quality performance from 2004 to 2008. The use of porous pavements for parking lots for new and redevelopment projects are one watershed-based strategy that can both mitigate impacts for new development and reverse impacts in areas with redevelopment. Surface infiltration capacity and frost penetration were measured monthly to assess winter performance. Because of the well-drained nature of the porous pavement and reservoir base, issues related to frozen media were minimized. Significant frost penetration was observed up to depths of 71 cm without declines in hydrologic performance or observable frost heave. No consistent statistical difference was observed for seasonal hydrologic performance with mean infiltration capacity ranging from 1,490 to 2,690 cm/h . Adverse freeze-thaw effects, such as heaving, were not observed, and for that reason, the life span is expected to exceed that of typical pavement applications in northern climates. Observed hydrologic response resembled shallow depth groundwater drainage, as is the goal for low-impact development designs. Peak flows were reduced by 90% to 0.58 m3/s/km2±0.74 in comparison with standard impervious cover=5.5 m3/s/km2±7.7 . There was exceptional water-quality treatment performance for petroleum hydrocarbons, zinc, and total suspended solids with nearly every value below detection limits. Only moderate removal was observed for phosphorous, and treatment for nitrate (NO3) was negative.