Porous (Permeable, Pervious) Pavement

Last year, I was part of a project where we designed a porous pavement system as part of the stormwater management plan, which was constructed late last year (videos at the end of this post if you do not want to read).

Typical Porous Pavement Cross-Section

 Image Source: NJDEP BMP Manual

As the name suggests, this type of asphalt or concrete mixture allows for infiltration of stormwater through the surface layer compared to traditional pavement (IMpervious). This is another example of green infrastructure technology "mimicking" the natural hydrologic cycle. Essentially, stormwater will infiltrate into the surface where the reservoir base course layer will temporarily provide storage prior to allowing stormwater to seep into groundwater through the uncompacted subgrade (groundwater recharge). Layer thickness, porous asphalt mixture, different configurations, types of material for your base course, addition of underdrains, etc. are site-specific.

Porous pavement systems have been successfully installed throughout the U.S.  Porous pavement systems can reduce stormwater runoff volume, rate and provide water quality benefits. If you have a project where you are proposing additional impervious areas already, you should definitely consider porous pavement as part of the stormwater management plan.

Of course, before you consider porous pavement, there are several site-specific conditions that must be met. These include, but are not limited to:

• load-bearing and infiltration capacities of subgrade,
• anticipated load and volume of traffic in proposed condition,
• anticipated use of the proposed site (e.g., do not install in areas with potential for spills and leakages of hazardous materials such as industrial and commercial areas),
• seasonal high groundwater table (groundwater separation criteria - typically the min. is at least 2-3 ft.),
• surface slopes (site grading),
• consideration for maintenance (must be committed to maintain the system), etc.

Below are two videos of the constructed porous pavement system from the project I worked on:

 

Enjoy!