TechNote 11 Permeable Pavement  

Permeable pavement systems, also referred to as pervious or porous paving, allow stormwater runoff to filter through the pavement section and infiltrate into the soil below. By allowing the water to infiltrate into the ground, the water undergoes absorption, filtration and microbiological degradation; in turn, reducing pollutants entering downstream water bodies. Permeable pavements also reduce the volume and velocity of stormwater runoff off site. There are four types of permeable pavement systems: pervious concrete (PC), porous asphalt (PA), reinforced turf or gravel (RT or RG), and permeable interlocking concrete pavers (PICP). All four variations include a surface pavement layer, aggregate bedding and base layers, filter fabric, and an underdrain if required.