Case Study:
Pervious Pavement
Before roads and parking lots, the majority of rainwater hit the landscape and soaked into the ground, was taken up by trees and plants, and was slowly returned to the hydrologic cycle through infiltration, evapotransipiration, or becoming part of the surface water flow. Paved surfaces changed all of that and flushed pollution-laden runoff directly into rivers and streams.
Pervious pavement (sometimes also called porous asphalt or porous pavement), consists of a permeable surface course underlain by a uniformly-graded stone bed. It allows stormwater to drain through the surface, be temporarily held in the voids of the stone bed, and then slowly drain into the underlying, uncompacted soil mantle, mimicking the natural system that once occurred on the site.
