Spatial modeling and analysis of chloride contamination due to deicing agents

Cases of chloride contamination in drinking water have become more frequent in recent years, creating serious health hazards and prompting local efforts to better monitor and understand the cause of rising chloride contamination levels. Regions with heavy winter precipitation and harsh conditions tend to experience higher levels of chloride in local drinking water. A small rural town located in the northeastern region of the US (“case study site”) has experienced particularly high levels of chloride contamination measured at several times the recommended maximum concentration posted by EPA Secondary Drinking Water Regulations. Local authorities in the Department of Public Health (DPH) of the state along with representatives from the Association of State Drinking Water Administrators have been tracking this trend for the past several years trying to determine the cause of the severely high levels of chloride contamination. One of the major suspected factors in these high contamination levels is deicing agents. The case study site experiences harsh winters with heavy snowfall, sleet, and freezing conditions, all of which require extensive preventative and reactive measures to mitigate the harmful effects they have on drivers and pedestrians. Of the many types of different deicing agents, road salt (sodium chloride) is the most popular solution, used heavily on major roadways across the US to keep people safe. As the name implies, this road salt contains chloride, and this chemical is soluble in water. The salt eventually mixes with precipitation and usually ends up flowing into a body of water which ultimately leads to drinking water, increasing chloride levels by various degrees in the water we use and consume daily. While road salt usage is certainly not the only cause of chloride contamination in drinking water, some studies point to a strong relationship between road salt and chloride levels. The primary goal of the research described in this project is to conduct an in depth correlation analysis to determine the major factors contributing to chloride contamination in the case study site. Such information could assist local authorities in developing policies or strategies to combat and mitigate contamination levels in drinking water.