Porous Asphalt

​Porous asphalt used in place of traditional impervious paving materials decreases the total amount of runoff leaving a site. It promotes infiltration of runoff into the ground, reduces the amount of pollutants carried to a storm drain or waterway, and aids with reducing peak runoff velocity and volume.

Developing land for residential, commercial and industrial use carries the detrimental effect of vastly increasing the amount of impervious surface area as land is paved to create roads and parking lots. During a storm runoff flows over impervious pavement picking up pollutants such as dirt, grease, oil, and transports these contaminants to streams and storm sewer systems.

In response to this issue, designers developed porous paving systems that allow runoff to pass through the pavement into a stone base, then into the soil below to recharge the groundwater supply. With proper installation and maintenance, porous paving allows for infiltration of up to 80% of annual runoff volume. Additionally, studies indicate that porous paving systems can remove between 65 and 85 percent of undissolved nutrients from runoff and up to 95% of sediment from run off.