SHORT-TERM AND LONG-TERM IMPACTS OF ROAD SALTING ON WATER QUALITY IN FRACTURED CRYSTALLINE BEDROCK

Several studies have shown an increasing trend in surface and ground water salinity, primarily due to the application of salt on pavement for deicing. In 2006, the Connecticut Department of Transportation implemented new practices for deicing by reducing the use of sand and incorporating the application of liquid salts. While these deicing developments are more efficient and less costly, the resulting impact is increased salt flux to shallow groundwater and bedrock aquifers.

This study uses specific conductance profiles (as a surrogate for chloride) from 2003-2016 to quantify the short-term and long-term impacts of salting on water quality in a crystalline bedrock well at the University of Connecticut in Storrs, CT. The average specific conductance in the upper flow zone increased from 270 μS/cm in 2003 to 1558 μS/cm in 2016. In the lower flow zone, specific conductance increased from 316 μS/cm in 2003 to 1106 μS/cm in 2016. In all cases specific conductance increased over time despite varying salt volume application, suggesting that concentrations may be cumulative. Continuous specific conductance measurements were also collected hourly from March 2014-October 2014 in the upper and lower flow zones to identify daily and monthly impacts of the spring snowmelt and precipitation events. The time-series shows a four-month lag in increasing specific conductance following water level rise. A temporary increase in specific conductance is observed following large precipitation events (> 2.3 cm) throughout the year, indicating that chloride is transported through bedrock aquifers for months following the final salt application of the season.