Internal Water Storage Enhances Exfiltration and Thermal Load Reduction from Permeable Pavement in the North Carolina Mountains

Abstract

Thermally-enriched stormwater runoff can negatively impact coldwater streams and their associated ecosystem services. The introduction of local and federal guidelines specifically targeting urban runoff temperature in the United States and Canada promulgate the use of practices that reduce thermal pollutant load from a catchment. Several stormwater control measures (SCM) have been shown to buffer thermal impacts to waterways by passing water through cooler subsurface media or by reducing overall discharge volume. Permeable pavement exposes stormwater to these mechanisms, which makes it a promising practice for thermal mitigation. A newly constructed permeable interlocking concrete paver (PICP) parking lot was monitored for 1 year in the mountain region of North Carolina to quantify runoff reduction, temperature buffering, and thermal load export. The effects on hydrology caused by internal water storage (IWS) in the pavement profile were also investigated by dividing the