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*Full Infiltration: Full infiltration designs are more effective because little if any of the pollutants generated on the impermeable surfaces leave the site as surface runoff.
*Full Infiltration: Full infiltration designs are more effective because little if any of the pollutants generated on the impermeable surfaces leave the site as surface runoff.
*Partial Infiltration: Partial infiltration designs with underdrains generate more runoff.
*Partial Infiltration: Partial infiltration designs with underdrains generate more runoff.
Studies in North Carolina have shown the average curve number of permeable pavements to range from a low of 45 to a high of 89. <ref>Bean, E.Z., Hunt, W, F., Bidelspach, D.A. 2007a. Evaluation of Four Permeable Pavement Sites in Eastern North Carolina for Runoff Reduction and Water Quality Impacts. Journal of Irrigation and Drainage Engineering. Vol. 133. No. 6. pp. 583-592.</ref>
Studies in North Carolina have shown the average curve number of permeable pavements to range from a low of 45 to a high of 89. <ref>Bean, E.Z., Hunt, W, F., Bidelspach, D.A. 2007a. Evaluation of Four Permeable Pavement Sites in Eastern North Carolina for Runoff Reduction and Water Quality Impacts. Journal of Irrigation and Drainage Engineering. Vol. 133. No. 6. pp. 583-592.</ref><br>
Partial infiltration designs with underdrains generate more runoff, and as a result, are often used in studies investigating the water quality impact of permeable pavements on surface waters. These studies show load reductions above 50% for total suspended solids, most metals, and hydrocarbons <ref>Legret, M and V. Colandani. 1999. Effects of a porous pavement structure with a reservoir structure on runoff water: water quality and fate of metals. Water Science and Technology. 39(2): 111-117</ref> <ref>Pratt, C.J., Mantle, J.D.G., Schofield, P.A. 1995. UK research into the performance of permeable pavement reservoir structures in controlling stormwater discharge quantity and quality. Water Science Technology. Vol. 32. No. 1. pp. 63-69.</ref> <br>
As with all stormwater infiltration practices, risk of groundwater contamination from infiltration of runoff laden with road de-icing salt constituents (typically sodium and chloride) is a significant concern. Chloride ions are extremely mobile in the soil and are readily transported by percolating water to aquifers.
==Construction Considerations==
==Construction Considerations==