1. INTRODUCTION
It is generally perceived that a major problem with permeable interlocking concrete pavements (PICP) is clogging. Closely related to this is the fact that permeable pavements can retain up to 90% of solids suspended in the water infiltrating the pavements [Pezzaniti et al., 2009]. However, experience in Europe shows reductions in PICP permeability due to clogging reach a near equilib-rium condition between 5 and 10 years after construction [Dierkes et al., 2002; Borgwardt, 2006] as pollutants are retained in the pavement. This needs to be considered in the design of PICP [Pezza-