DETERMINING HOW TOPOGRAPHY AND HYDRAULIC HETEROGENEITY CONTROL TÓTH FLOW CHARACTERISTICS AND IMPACT THE TRANSPORT OF ROAD SALT IN AQUIFERS: A GUIDE FOR POLICY AND MANAGEMENT

Usage of road salt as a deicing agent continues to dominate areas with hazardous winter weather conditions due to its effectiveness, availability, and relatively low cost. This reliance has the potential to cause damage to subsurface aquifers, contaminate fresh groundwater resources, and impact public health and the environment. Many surface water bodies are finding elevated salt concentrations in the summer months. This shows that road salt is being stored in aquifers over time and slowly getting released into streams during the summer as base-flow. However, the process of subsurface salt storage, its residence time, and how topography driven flow and aquifer heterogeneity controls these processes are not well understood. In this study, a computational model that solves for groundwater and advection-dispersion equations is formulated to simulate how road salt is transported in subsurface aquifers. Sensitivity to variables such as water-table topography, stratigraphic heterogeneity, presence of clay and sand lenses, and frequency of salt loading related to climate change are studied. Each topographic and heterogenic scenario are evaluated for how the concentration of salt builds up and is released over time, its flushing intensity, and the mean residence time. The results from these computational models will aid policy makers to craft legislation to minimize the impact of the damages associated with road salt. Using these results, we make suggestions to the policy makers of potential suggestions of policy that both balances maintaining safety on roadways and protecting our groundwater resources.