Strategies To Address Stormwater Runoff Issues Through Permeable Surfaces
Conventional paved pavement surfaces are relatively impermeable, allowing precipitation to run off much faster than it does from vegetated or undeveloped surfaces. In addition, in urban environments, runoff from impermeable surfaces is often directed to stormwater collection systems and thus is not absorbed into the nearby soil. That runoff, because it does not benefit from being naturally filtered through the soil, can pollute and raise the temperature of the nearby surface waters and streams to which it is being diverted. Furthermore, the collection of runoff in this manner during high precipitation events can cause stormwater collection systems to overflow, potentially resulting in flooding and erosion because of the speed with which the runoff leaves the paved surface. In cases where the stormwater collection system is combined with the sanitary sewage system, the release of raw sewage may occur as the result of the system being overwhelmed during high precipitation events, causing significant environmental and economic impact for treatment and clean up. Finally, typical stormwater management solutions, including the reliance on retention ponds, are difficult to accommodate in areas with space constraints (such as built-up urban areas); consequently, innovative solutions to reducing road surface runoff, including the use of permeable pavement surfaces, are needed.
Practices available to pavement managers, designers, and specification developers that can be used to address stormwater runoff issues are provided in table 1. See Chapter 6 (.pdf) of the Reference Document for more details.
|Stormwater Runoff Objective||Stormwater Runoff Improving Practices||Economic Impact||Environmental Impact||Societal Impact|
|Increase Structural Capacity for Application in High-Speed, High-Load Areas.||Pervious concrete.
|Increased initial cost over comparable impermeable concrete and asphalt. Cost of handling and treating stormwater may be less than other BMP.||Improved stormwater quality. Impact on other impact categories has not been evaluated.||Uncertain.|
|Permeable pavers.||Not applicable for high-speed applications.||Not applicable for high-speed applications.||Not applicable for high-speed applications.|
|Vegetated pavement.||Not applicable for high-speed applications.||Not applicable for high-speed applications.||Not applicable for high-speed applications.|
|Create Lower Maintenance Permeable Pavement Surfaces.||Pervious concrete.
|Research is still underway to develop improved durability without sacrificing hydraulic performance, and to develop better structural designs. Trade-offs between initial and life-cycle costs to be determined.||Longer life pavement designs should reduce environmental impact of materials production and construction.||Longer life pavement designs should improve societal impact of repeated construction.|
|Vegetated pavement.||Improved designs for vegetation selection and management should reduce economic, environmental (water use) and societal impacts.||Improved designs for vegetation selection and management should reduce economic, environmental (water use) and societal impacts.||Improved designs for vegetation selection and management should reduce economic, environmental (water use) and societal impacts.|
|Understand the Potential for Ground-water Contamination.||All permeable pavement types.||Investment required in research to determine level of risk and mitigation approaches, although initial results positive.||Uncertain. Once the level of risk is fully assessed it can be weighed against alternatives, as needed.||Uncertain. Once the level of risk is fully assessed it can be weighed against alternatives, as needed.|