surfaces promote stormwater infiltration through one of two methods:
either through voids in the material itself or voids surrounding the
material. Impermeable surfaces increase the stormwater runoff rate
and quantity potentially causing pollution and erosion of local
Permeable pavements are engineered asphalt or concrete surfaces
designed to let stormwater pass through voids in the material
itself. This is accomplished by removing small aggregate from the
paving material during the manufacture process.
In contrast, permeable pavers are effective due to an open grid that is
created in between a network of interlocking paving materials.
Bricks are a common example of permeable pavers. Stormwater
infiltration occurs due to the voids in between the brick rather
than the brick itself. Permeable paver systems are available which
contain larger voids (see Figure 1). Vegetation, typically grass, is
grown in the voids. Gravel beds are often placed underneath
permeable pavers and pavements to increase infiltration capacity.