User:Nestorfi/sandbox

Climate
Cold climates may present special challenges. Road salt contains chlorides that could migrate through the porous pavement into groundwater. Sand cannot be used for snow and ice control on pervious asphalt or concrete because it will plug the pores and reduce permeability. Infiltrating runoff may freeze below the pavement, causing frost heave, though design modifications can reduce this risk. These modifications include higher porosity, thus limiting the amount of water saturated into the paving and reducing the risk of freezing. These potential problems do not mean that porous pavement cannot be used in cold climates. Porous pavement designed to reduce frost heave has been used successfully in Norway. Furthermore, experience suggests that rapid drainage below porous surfaces increases the rate of snow melt above. This is best achieved by placing 6 to 18 inches of rock or gravel as it might not only support the paving, but also increase draining into the soil.