EVALUATING MISSOURI'S OZARK AQUIFER WATER-QUALITY FOR A POTENTIAL CARBON SEQUESTRATION INJECTION MONITORING PROGRAM

Of the three major aquifer systems within Missouri (Springfield Plateau aquifer, Ozark aquifer, and St. Francois aquifer), the Ozark aquifer is the most accessible, and regionally available aquifer system. Previous studies have simplified the Ozark aquifer as an Upper Cambrian to Devonian aged carbonate aquifer system with homogenous water quality. More recent data and modern database analysis methods offer the possibility of subdividing the Ozark aquifer. Unfortunately, in order to achieve satisfactory production rates, municipal wells penetrate different sections of the Ozark aquifer, Historically, little or no effort was made to investigate if any sections of the Ozark aquifer possessed unique water-quality. Fortunately, detailed strip logs have been archived by Missouri’s Department of Natural Resources (MoDNR) which can provide the detailed stratigraphy of wells that withdraw water exclusively from the Ozark aquifer. In addition, periodic Ozark aquifer water quality data has been archived by the US Geological Survey (USGS), MoDNR, and the US Environmental Protection Agency (EPA). Therefore, it is now possible to investigate the possibility of constituent Ozark aquifer formations yielding unique water quality by processing the combined database. The Missouri Carbon Sequestration Project, a feasibility study of shallow CO2 injection into the deeper St. Francois aquifer, has generated interest for a greater understanding of the Ozark aquifer in order to monitor potential changes that may result from sequestration within the St. Francois aquifer. By evaluating the aforementioned database, and using geochemical modeling simulations where needed, the historic assumption that the Ozark aquifer is a single homogenous unit will be tested. Details of this methodology and results of the testing will be presented along with our conclusion as to whether the Ozark aquifer should be considered a single hydrostratigraphic unit, or if data supports sub-dividing the Ozark aquifer into two or more hydrologic sub-units. This material is based upon work sponsored by the Department of Energy National Energy Technology Laboratory under Award Number DE – FE0001790 to City Utilities of Springfield, MO.