IMPACT OF LAND USE ACTIVITIES ON GROUNDWATER GEOCHEMISTRY AND IDENTIFICATION OF AQUIFER PARAMETERS FROM A CCSU WELL FIELD

Central Connecticut State University (CCSU) constructed five monitoring wells into an unconfined aquifer back in October 2016 on a grass plot. The well field has a central well drilled to a depth of 25 feet with a 2-inch diameter casing, surrounded by four other wells drilled to a depth of 20 feet below the surface with an inch diameter PVC casing. The wells were fully developed, producing about 7-10 Liters of water per minute, and have been used for teaching hydrogeology, geochemistry, and environmental-related classes since then. However, about a year ago a gravel parking lot was built for students on the site of the well field area. Studies have shown the influence of vehicular emissions and the use of road salt on groundwater chemistry. Thus, this research project focused on the characterization of the aquifer parameters and assessment of well field water chemistry and usability. To accomplish this, four Hobo Pressure Transducers were deployed into the wells to record periodic changes in water level at 30-second intervals. Bi-monthly water samples are extracted from each well, with analyses conducted for cations using an ICP-OES, and anions using a Shimadzu HPLC-IC. In addition, all-day constant rate and recovery pumping tests will be conducted to ensure steady-state drawdown has been achieved. From these tests, along with information of aquifer thickness from the well-logs, aquifer transmissivity, hydraulic conductivity, and storativity will be determined with analysis utilizing Aqtesolv software. These aquifer parameters are useful in discovering the rate of porewater movement and possible yield of groundwater. The HOBO data loggers showed a high correlation in water fluctuation with precipitation events with little to no delayed response indicating a possible high infiltration and recharge rates to the aquifer. Chemical analyses from the wells indicate elevated levels of Chloride (600-725 ppm), Sodium (280-320 ppm), Calcium (130-170 ppm), and Magnesium (35-50 ppm). No detectable trace-element concentrations were observed in this well. Data monitoring will continue indefinitely to provide a long-term record which will provide enough background dataset for use in teaching and professional development.