Although permeable pavements have been used all over the world in recent years to infiltrate and treat stormwater, only limited research has been undertaken to investigate and compare the long-term performance of these sustainable urban drainage system devices. This paper presents the results of an extensive international review of research on the reduction of infiltration capacity of permeable pavements over time. The results of these studies, coupled with specific knowledge of the key environmental factors on the individual research locations and infiltration testing methods used, enables the maintenance of these SUDS to be strategically planned in order to meet specific European and international infiltration capacity guidelines.
This study describes field investigations designed to compare the infiltration capacities of 55 permeable pavement systems installed in the Netherlands and in Australia. The ages of the pavements varied from 1 to 12 years. Using infiltrometer testing, the performance of the pavements has been compared in terms of their ability to infiltrate a three month average recurrence interval storm event in the case of the Australian pavements or the minimum specification for European infiltration capacities of 97.2 mm/h for the Dutch pavements. Many of the tested pavements broadly follow a hypothetical decay curve of infiltration rate with age of pavement. However, these are clustered into two distinct groups (Dutch and Australian) with the older Australian pavements appearing to maintain higher infiltration rates relative to their age. The study has shown that the performance of the clogged permeable pavement systems was still generally acceptable, even after many years in service.
This research used a newly developed, full-scale infiltration testing (FSIT) procedure to determine the saturated surface infiltration rate of 16 existing permeable pavement installations in the Netherlands that have been in service for a number of years. Newly installed permeable pavements in the Netherlands must demonstrate a minimum infiltration capacity of 194 mm/h (540 L/s/ha). Only four of the 16 pavements tested in this study had an infiltration capacity higher than 194 mm/h. Most previous research has focused on unsaturated infiltration rates. However, the results of this study show that the difference in infiltration capacity between saturated and unsaturated can differ by up to 300%. If the unsaturated infiltration capacity is used as design input for computer models, the infiltration capacity may be significantly overestimated. The study demonstrated that the FSIT method is a reliable and accurate way to measure surface infiltration rates of permeable pavements. However, it is recommended that a minimum of three different FSIT tests should be undertaken at the same pavement location, and that the results should be averaged, to ensure appropriate infiltration rates are observed, recorded, and used in design. The results of this study should help stormwater managers with the planning, testing, and scheduling of maintenance requirements for permeable pavements with more confidence so that they will continue to perform satisfactorily over their intended design life
