Forensic engineering as a tool for permeable pavement hydrological maintenance planning: lessons learned and future prospects

Resumen

Permeable pavements (PP) are a robust stormwater control measure (SCM) when it comes down to source point runoff control from hard urban surfaces, becoming comprehensively investigated from different angles, with a particular focus in operation and maintenance lately. This paper reports the experience gathered during 13 years of monitoring activities on a parking lot with no maintenance carried whatsoever, flagging a bottom-line performance whilst opening new viewpoints for hydraulic performance analysis. Porous asphalt (PA), porous concrete (PC) and interlocking concrete pavement (ICP) were tested using international standard methods such as the ASTM’s C1781/C1781M-15 and C1701/C1701M-17a, the Spanish normative NLT-327/00 and the European Standard EN 12697-40. This investigation provides trends in infiltration rates, showing the decrease in infiltration capacity for each PP, signposting hydraulic failure for porous mixtures after 5-6 years with no maintenance. Instead, ICP were found to keep providing infiltration rates above 2,500 mm/hr after 10 years. What is more, a comparative analysis of their hydraulic response after 11 and 13 years did not yield any statistically significant difference, which may point out to a threshold of steady minimum infiltration with time. Overall, this research informs about optimised times to deliver maintenance activities with the aim to keep PP filtration functionality. Finally, a methodology for accurate monitoring, based in this long-term experience, is proposed in order to improve PP design and maintenance efficiency.