Porous asphalt provides better water quality - Pt1
Posted by Jesse Willoughby on Tue, Apr 21, 2009 @ 12:55 PM
Porous asphalt...
• Conserves water
• Allows for better use of land
• Reduces runoff
• Promotes infiltration
• Cleans stormwater
• Replenishes aquifers
• Protects streams
Porous asphalt offers a powerful tool in the toolbox for storm-water management.
In the natural environment, rainfall sinks into soil, filters through it, and eventually finds its way to streams, ponds, lakes, and underground aquifers. The built environment, by way of contrast, seals the surface. Rainwater and snowmelt become unoff which may contribute to flooding. Contaminants are washed from surfaces directly into waterways without undergoing the filtration that nature intended.
For these reasons, managing stormwater is a significant issue in land use planning and development. Stormwater management tools can serve to mitigate the impact of the built environment on natural hydrology. Unfortunately, however,they also can lead to unsound solutions such as cutting down stands of trees in
order to build detention ponds.
Porous asphalt pavements allow for land development plans that are more thoughtful, harmonious with natural processes, and sustainable. They conserve water, reduce runoff, promote infiltration which cleanses stormwater, replenish aquifers,
and protect streams.
A typical porous pavement has an opengraded surface over an underlying stone recharge bed. The water drains through
the porous asphalt and into the stone bed, then, slowly, infiltrates into the soil. If contaminants were on the surface at the time of the storm, they are swept along with the rainfall through the stone bed. From there they infiltrate into the subbase so that they are subjected to the natural processes that cleanse water.