Abstract
Permeable interlocking concrete pavements (PICPs) are being increasingly utilised in urban developments globally to promote stormwater infiltration, reduce catchment runoff volumes and to improve the quality of downstream receiving waters. However, clogging of PICPs due to the sediment contained in stormwater runoff has been shown to significantly reduce the infiltration capacity of PICPs over time. There have been numerous PICP clogging studies undertaken in the past. Many of these studies have used laboratory-based PICP models, using synthetic stormwater, in an attempt to replicate and predict the clogging processes that occur in PICP field installations. A variety of sediment types and sizes, and stormwater application rates have been used in these studies with mixed results. The current study investigated the effects that varying sediment types, varying particle size distributions and varying testing durations had on clogging of PICP models. Eighteen specially constructed PICP models were tested in the laboratory using the accelerated semi-synthetic stormwater simulation technique. Three different sediment types were tested: 1) specialised silica sand; 2) real stormwater sediment <300 μm and; 3) real stormwater sediment <1.18 mm. Six different stormwater application rates (intensities) were tested in the study. The study results generally indicated that silica sediment clogging processes were inversely proportional to the stormwater application rate. That is, lower application rates (longer test duration) resulted in less clogging of the PICP models. Conversely, for the real sediment <300 μm, the clogging processes were directly proportional to the stormwater application rate, i.e., lower application rates (longer test duration) resulted in more clogging of the PICP models. Stormwater application rates did not appear to effect the clogging results of real sediment <1.18 mm. The study results have revealed new insights into the reliability and validity of laboratory-based PICP clogging testing results and how the results should be viewed.