Analysis of stormwater runoff from permeable friction course

Recently, the Texas Department of Transportation began using Permeable Friction Course (PFC), a 5 cm overlay of porous pavement that is applied over conventional pavement. PFC was initially developed because it allows water to drain off the surface of roads much more rapidly, thus reducing visual impairment due to splash and spray as well as reducing the risk of hydroplaning. While investigating the water quality of stormwater runoff, researchers at the University of Texas discovered that PFC caused a reduction in many common stormwater pollutant concentrations. Monitoring of stormwater at one site has been ongoing for 5 years without any indication of a decline in water quality. A second location provided paired samples to analyze the particle size distribution. Results show a significant reduction in the mass of particles commonly associated with heavy metals and nutrient loads. A third location was chosen based on tests indicating it to have a lower hydraulic conductivity relative to other locations. The paired samples provided a comparison of runoff quality at a site believed to be heavily clogged. The results show PFC continues to produce significantly lower runoff pollutant concentrations despite the decreased hydraulic conductivity.