EVALUATING THE EFFECT WINTER DE-ICING HAS ON GROUNDWATER QUALITY UNDER PERMEABLE PAVEMENT

Permeable pavement has increasingly been used to replace traditional pavement in urban landscapes to help reduce loading to storm water systems and to increase groundwater recharge. While studies show that permeable pavement reservoirs are capable of filtering out chemical contamination, emphasis has been placed on the removal of hydrocarbon contaminants with little attention paid to dissolved ions. This project will evaluate the effect winter salting has on shallow groundwater beneath permeable pavement. The primary contaminant of concern is chloride, due to its mobility in soils and groundwater. Issues related to chloride contamination include increases in sodium content of groundwater and surface water, as well as the mobilization through cation exchange of calcium, magnesium, and potentially uranium and radium in native soils and bedrock. The study area contains an 8400 square foot permeable pavement parking lot located in Storrs, Connecticut. Monitoring wells have been installed at 3 locations throughout the site, equipped with electrical conductivity (EC) probes. Water samples will be collected biweekly and analyzed for chloride and major metals. EC values have been compared with chloride laboratory analyses creating a predictive relationship between observed EC levels and chloride content, allowing EC data to serve as a proxy for chloride concentrations. Long term EC and water level data will be collected continuously at 10 minute intervals for 1 year and be used to monitor for potential chloride changes in response to infiltration of snow melt containing dissolved de-icing salts. If successful, this project will help guide future permeable pavement installations and winter salting best practices.