Water Quality Benefits of the Permeable Friction Course
Research Idea Scope
The Permeable Friction Course (PFC also known as Open Graded Friction Course)is a two inch thick overlay applied to existing pavement to reduce splash and spray behind vehicles, and to reduce noise. Limited research in the US and Europe indicates that this material also reduces the pollutants in runoff by as much as 90%. PFC accomplishes this by trapping pollutants within the pore spaces of the pavement and reducing the washoff of pollutants from the bottom of vehicles during storm events. Additional research is needed to confirm the water quality benefits, determine how long the water quality benefits persist, and to identify appropriate maintenance practices to preserve the water quality benefits.
Urgency and Payoff
PFC substantially reduces the concentration of many pollutants in stormwater runoff. The observed reduction in pollutants may allow DOTs to incorporate stormwater treatment into the pavement itself, rather than constructing and maintaining the expensive structural treatment controls now used. Many DOTs are looking for highway specific stormwater controls, appropriate for linear systems. If the water quality benefits and maintenance requirements can be adequately documented, this material, which is widely used for safety reasons, can help DOTs meet water quality requirements at no additional cost, since the safety aspects alone justify its use.
Michael Barrett, University of Texas at Austin