About Porous Asphalt
General Information Performance Data Water Quality Treatment Process Design


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Water Quality Treatment Process

1. Rain drains through the porous asphalt and the choker course and into the sand filter course.

2. In the filter course, the physical process of filtration removes fine particulates from the solution, and the chemical process of sorption binds contaminants like heavy metals, petroleum hydrocarbons, and phosphorus to the sand surfaces. It is likely that some microbial activity also degrades petroleum hydrocarbons and nutrients.

3. Water passes into the infiltration reservoir of uniformly graded crushed stone, where infiltration into sandy clay loam soils can occur.

4. Treated water that flows below the elevated subdrain infiltrates into the subgrade, where it can recharge the groundwater supply.

5. When a storm’s rainfall exceeds system design, water flows through the elevated subdrain to the surface. If the system is completely drained from a previous storm, it can store a four-inch rain event in its infiltration basin. The void spaces contained within the entire subbase provide sufficient storage for a 15-inch rain event. This design reflects the researchers’ need to install in poor soils and high groundwater. UNHSC recommends other design criteria for other settings.