Year-round monitoring of chloride releases from three zero-exfiltration permeable pavements and an asphalt parking lot. (15th February 2023)

• Record Type: Journal Article
• Authors: Sehgal, Kirti; Sidhu, Virinder; Oswald, Claire; Drake, Jennifer
• Is Part Of: Journal of environmental management. Volume 328(2023)
• Publication Date: 2023-02-15
• Subjects: Chloride -- Road salt -- Permeable pavement -- Permeable interlocking concrete pavers (PICP) -- Porous asphalt -- Pervious concrete; Environmental policy -- Periodicals; Environmental management -- Periodicals; Environment -- Periodicals; Ecology -- Periodicals; 363.705
• DOI: 10.1016/j.jenvman.2022.116903
• Languages: English
• ISSNs: 0301-4797

Abstract

Abstract: Winter deicers, though essential for maintaining safe pavement conditions in winter, increase chloride (Cl − ) concentrations in receiving water bodies above recommended environmental guidelines. Zero-exfiltration or lined permeable pavement is an important technological innovation for controlling particulate-bound pollutants at the source. As stormwater does not infiltrate into the ground, soluble pollutants like Cl − are ultimately discharged into receiving water bodies. Our aim was to examine Cl − concentrations in effluents from three zero-exfiltration permeable pavement cells (Permeable Interlocking Concrete Pavement (PICP), Pervious Concrete (PC), Porous Asphalt (PA)) and compare them with runoff from a Conventional Asphalt (ASH) cell. The study conducted at a parking lot in St. Catharines, Ontario, Canada, from January 2016 to May 2017 observed that the permeable pavements provided only temporary attenuation of Cl − during winter but exhibited a quick release during spring melt. Cl − concentrations and loadings were different for each permeable pavement system in terms of timing and magnitude. Cl − concentration in ASH runoff frequently had very high spikes (21, 780 mg/L); however, the median winter Cl − concentration in ASH runoff was lower than Cl − levels in the permeable pavements' effluents and later declined drastically after spring melt, but in few instances, was above the chronic water quality guideline (120 mg/L). The average event mean concentration (EMC) of Cl − was 1600 and 120 mg/L in the permeable pavements' effluents during salting and non-salting season, respectively. In one year, each permeable pavement system released approximately 67–81 kg of Cl − with significant differences being observed in Cl − loads between the 2016 and 2017 seasons. Therefore, a multi-year data collection and monitoring plan captured the variability in winter conditions. The study provided insights into the behaviour, retention and release of Cl − from traditional and permeable hardscape surfaces and possible avenues for Cl − attenuation, source control and aquatic habitat conservation. Graphical abstract: Fig. 1: Seasonal cumulative distribution functions of 15-min Cl − concentrations in stormwater from different permeable pavements (PICP, PC and PA). Non-Salting season 2017 only includes measurement from May 2017. The orange dashed line signifies the Canadian Water Quality Guidelines (CWQG) chronic limit for Cl − (120 mg/L), and the brown dashed signifies the CWQG acute limit for Cl − (640 mg/L). Since Cl − concentrations range by order of magnitude, different x-axis scales are used for readability for each season. Image 1 Highlights: Multi-year data collection study captured variability in winter conditions. Permeable pavements provided temporary attenuation of chloride during winter. Permeable pavements exhibited a quick release of chloride during spring melt. Conventional asphalt runoff had very high spikes of chloride concentration. The ecological implications of temporary attenuation of chloride were unclear.