Written By: Bill Handlos, P.E. Not All Porous Pavements Clog Well-designed porous pavement systems resist clogging When designing porous pavement systems, it is important to consider the effects of silt, grit, sand, and other fine material that can slow or stop water from infiltrating. However, it is a common myth that all porous pavement systems eventually clog. A good PPS system design, simple but effective site design, and careful construction inspection and field guidance can all but eliminate the clogging threat. System Design Do’s and Don’ts Cross-sections will vary according to the porous pavement selected, but following some simple practices can ensure a successful system with long-lasting percolation. Never place filter fabric immediately below the porous pavement surface. Whether you are using pervious concrete, porous asphalt, polyethylene injection-molded paving block (such as GEOBLOCK vegetated or GEOPAVE aggregate PPS), or concrete paving stone, your cross-section should allow free flow from the paving layer to the base and storage layers. The last thing you want is to trap water in your pavement layer. Surprisingly, at least one aggregate PPS manufacturer sells their product with a filter fabric attached to the bottom of the units. Always use a filter fabric or other separator at the bottom of… Read more »