Highway deicing salt dynamic runoff to surface water and subsequent infiltration to groundwater during severe UK winters

Abstract

Dynamic impact to the water environment of deicing salt application at a major highway (motorway) interchange in the UK is quantitatively evaluated for two recent severe UK winters. The contaminant transport pathway studied allowed controls on dynamic highway runoff and storm-sewer discharge to a receiving stream and its subsequent leakage to an underlying sandstone aquifer, including possible contribution to long-term chloride increases in supply wells, to be evaluated. Logged stream electrical-conductivity (EC) to estimate chloride concentrations, stream flow, climate and motorway salt application data were used to assess salt fate. Stream loading was responsive to salt applications and climate variability influencing salt release. Chloride (via EC) was predicted to exceed the stream Environmental Quality Standard (250mg/l) for 33% and 18% of the two winters. Maximum stream concentrations (3500mg/l, 15% sea water salinity) were ascribed to salt-induced melting and drainage of highway snowfall without dilution from, still frozen, catchment water. Salt persistance on the highway under dry-cold conditions was inferred from stream observations of delayed salt removal. Streambed and stream-loss data demonstrated chloride infiltration could occur to the underlying aquifer with mild and severe winter stream leakage estimated to account for 21 to 54% respectively of the 70t of increased chloride (over baseline) annually abstracted by supply wells. Deicing salt infiltration lateral to the highway alongside other urban/natural sources were inferred to contribute the shortfall. Challenges in quantifying chloride mass/fluxes (flow gauge accuracy at high flows, salt loading from other roads, weaker chloride-EC correlation at low concentrations), may be largely overcome by modest investment in enhanced data acquisition or minor approach modification. The increased understanding of deicing salt dynamic loading to the water environment obtained is relevant to improved groundwater resource management, highway salt application practice, surface-water - ecosystem management, and decision making on highway drainage to ground.

Emergent archetype patterns of coupled hydrologic and biogeochemical responses in catchments

“…All three patterns can be characterized by an empirical power law relationship, C = aQ b , with the exponent b indicating the specific C-Q archetype [Godsey et al, 2009;Herndon et al, 2015;Jawitz and Mitchell, 2011;Musolff et al, 2015;Zhang et al, 2016]. For dilution (b < 0), C decreases with increasing Q, as observed for silica [Herndon et al, 2015;Maher, 2011] in "natural" catchments, or Na + and Cl À in urban catchments [Rivett et al, 2016]. For the enrichment archetype (b > 0), C increases with increasing Q, as found for dissolved organic carbon [Ledesma et al, 2015;Seibert et al, 2009;Strohmeier et al, 2013].…”

Chloride source delineation in an urban‐agricultural watershed: Deicing agents versus agricultural contributions

“…The magnitude of salinization in northern regions has a strong relationship with land use, with urban land use associated with the largest increase in Cl − concentration (Dugan et al, 2017; Herlihy, Stoddard, & Johnson, 1998; Kaushal et al, 2005; Lax, Peterson, & Van Der Hoven, 2017). Overland flow and infiltration during precipitation and melt events is the primary transport mechanism for deicing salt to move to streams and into the subsurface (Cañedo‐Argüelles et al, 2013; Lax & Peterson, 2009; Ledford et al, 2016; Rivett et al, 2016). Elevated base flow salinity is attributed to storage of road salt derived Cl − in groundwater (Cañedo‐Argüelles et al, 2013; Kaushal et al, 2005; Kelly et al, 2008).…”

A Review of the Contribution of Mechanomutable Asphalt Materials Towards Addressing the Upcoming Challenges of Asphalt Pavements

“…Given that hazardous weather conditions can increase the susceptibility of traffic accidents, especially with snowfall being a particularly high risk factor in road accidents [42], these solutions can be used as environmental-friendly and smart alternative strategies for traditional "de-icing salts". While these salts have been shown to be economically accessible and effective, they affect the roadside soil, underground and surface water and vegetation integrity [43,44], as well as the long-term structural performance of the road infrastructure and vehicle health [45]. [30,48,53] With respect to the second type of maintenance operation, with the aim to transform roads into more resilient structures through self-healing, recent research efforts have designed and evaluated the use of encapsulated healing agents (oily rejuvenators) [54][55][56] and the effect of resting periods [57].…”