Date of Award
Master of Science (MS)
Radium is a common contaminant to the deep Cambrian- Ordovician aquifer in northern Illinois. Deep groundwater aquifers are used as fresh water resource in many parts of the world. Due to overuse, increase in salinity, natural and human-driven contamination, sustainability of these aquifer systems is uncertain. The purpose of this study is to better understand the groundwater flow system in deep bedrock aquifers in northern Illinois, and its control on the radium contamination in Rochelle’s Public Water Supply Wells (PWSW). We have tested two hypotheses: (1) the Radium (Ra) transport is driven by large pumping centers that interrupt groundwater flow (groundwater divide) and direct elevated level of Ra from areas that have already recorded Ra to PWSW and (2) Increased pumping results in leakage of water from the Franconia Formation which is fraught with glauconite into the PSWS that is opened to the Ironton-Galesville aquifer. The hypotheses are tested using a 3D steady-state numerical groundwater model using MODFLOW. The numerical model was calibrated using in-situ groundwater level measurement data, and pseudo wells created from head data from Illinois Groundwater Flow Model (IGWFM), with Mean Error (ME), Root Mean Squared Error (RMSE), and coefficient of determination (R2) values of 0.07 m, 1.74 m, and 0.991, respectively. Using the calibrated model, scenario models, stochastic and capture zone analysis were conducted. The results indicated that the large pumping centers have less control on the shift in regional groundwater divide, hence preventing flow of radium rich waters to Rochelle’s PWSW. On the other hand, capture zone results and mass balance shows leakage from the Franconia Formation into the Ironton-Galesville aquifer which might indicate the source of radium being upgradient into the PWSW. Generally, it is recommended to tap water from shallower bedrock aquifers located above the Franconia Formation in Rochelle.
Oware, Prince Kojo, "Capture Zone Analysis of a Wellfield to Assess Contaminant Transport" (2019). Theses and Dissertations. 1119.