Application of Porous Concrete Infiltration Techniques to Street Stormwater Inlets That Simultaneously Mitigate against Non-Point Heavy Metal Pollution and Stormwater Runoff Reduction in Urban Areas: Catchment-Scale Evaluation of the Potential of Discrete and Small-Scale Techniques

The expansion of pervious areas is an essential and common concept in mitigating non-point pollution runoff in urban areas. In this review, literature related to the expansion of pervious areas is introduced. In addition, the potential application of porous concrete as a medium for constructing the bottom and side walls of street stormwater inlets is investigated. The effectiveness of this medium in reducing (i) the stormwater runoff volume via porous concrete by exfiltrating from the bottom and the wall, and (ii) the heavy metal pollution runoff loads via infiltration through the porous concrete is assessed using data obtained by the author and published in the literature. The urban hydrological model Infoworks ICM (Innovyze) was used to estimate the exfiltration rates through the porous concrete plates set at the bottom and side walls of the street stormwater inlets. The exfiltration rates used in the pre-reported literature varied depending on the methods used. In the present study, sensitivity tests were performed by changing the exfiltration rates. The results of this study indicated that porous concrete used at only the bottom and side walls of the street stormwater inlets is suitable for reducing the runoff volume and removing any heavy metals from stormwater at a catchment scale.