Permeable pavements can be used as a stormwater management approach, and examples may include pervious concrete, porous asphalt, concrete grid pavement, or several others.1 These designs allow for runoff reduction by allowing for slow infiltration into the top layer and then into the underlying layers of soil and gravel.2,3 Permeable pavement usually consists of an underlying stone reservoir that temporarily stores runoff as it infiltrates into the soil. Conventional, impermeable pavement surfaces force rainwater to run off much faster without absorbing into nearby soil.4 Alternatively, permeable surfaces can reduce runoff pollution by filtering out harmful substances before entering stormwater collection systems and nearby streams.
Additionally, reducing directly connected impervious areas (DCIA) with permeable pavements or other green infrastructure designs can lower the accumulation of pollutants on impermeable surfaces and improve water quality.5 Roadways, parking lots, and other impervious structures prevent infiltration and can contribute to flooding.
How it Helps
Permeable pavement designs have many benefits, including reductions in runoff volume, pollutant concentrations, and runoff temperature.6 It can also prevent flooding and erosion by controlling runoff velocity.
This solution is an example of a low impact development (LID) practice that protects water quality and aquatic habitats by mimicking or preserving natural stormwater drainage processes.7,8 This approach focuses on recreating natural landscape features and minimizing impervious structures. By emphasizing infiltration, LID can reduce runoff, minimize flooding risk, reduce groundwater pollution, mitigate the urban heat island effect, and improve neighborhood aesthetics.
Due to its load capacity and structural limitations, permeable paving is typically only used in low-traffic areas, such as sidewalks, parking lots, driveways, or overflow parking areas.9 When determining the location of permeable pavements, planners and engineers should also analyze soil types and sources of runoff to ensure that the site is acceptable.
The type of permeable pavement design is an important factor to consider before implementation since various designs have different runoff volume and pollutant reduction capabilities.2 Paving depth, materials, and compactness can all influence permeability and effectiveness.9
Permeable pavements tend to cost more than impermeable surfaces; however, construction costs will largely be depend on the application.9 For instance, permeable pavements may reduce the need to construct other stormwater management structures and result in other cost savings.
Permeable pavements should be regularly maintained to ensure their long-term performance. This can include visual inspections and measuring surface infiltration rates.10
1) Texas A&M AgriLife Study on Permeable Pavement Types
A study conducted by a research team at the Texas A&M AgriLife Center at Dallas analyzed the performance of different kinds of permeable pavement, including grass pavers, concrete grid pavers, porous concrete, and plastic reinforced gravel pavers. The study found an average runoff volume reduction ranging from 73% to 85%.
2) Westfarms Mall, Connecticut Grass Pavers
Westfarms Mall in Connecticut built over four acres of grass pavers to handle overflow mall parking. This allowed the mall to expand its parking capacity while not needing to enlarge the current storm drainage system.