Water Resources Research Act Program

Details for Project ID 2019SD239B

Assessment and improvement of performance of septic systems in cold climates

Institute: South Dakota
Year Established: 2019 Start Date: 2019-05-31 End Date: 2020-05-30
Total Federal Funds: $10,000 Total Non-Federal Funds: $20,000

Principal Investigators: Stu Geza

Abstract: Approximately 25 percent of South Dakota residents rely upon on-site septic systems for wastewater treatment. About 90 percent of Rapid City’s drinking water originates from groundwater in the Madison aquifer. The Madison aquifer is composed of limestone and dolomite, and is karstic, highly permeable and heterogeneous. Two of the hydrogeologic settings in the Black Hills area are alluvial deposits and karst limestone formations. These aquifers provide the largest single source of drinking water in the Black Hills; however, because of their karstic characteristics, recharge areas for these aquifers are sensitive to contamination. Various studies have indicated that there are several potential sources of contamination in recharge water for the Madison aquifer, including wildlife, livestock, and septic systems. While there is some knowledge of contaminant sources for the groundwater in the aquifer, there is little understanding about contaminant flow paths and potential risks. The goal of this study during the initial phase is to conduct a bench scale investigation of the potential for groundwater and surface water contamination from septic systems under vulnerable soil, geological settings, and climate conditions. The research will be extended to a watershed scale investigation and evaluation of options for effective subsurface treatment system to improve treatment performance. A laboratory experiment will be conducted to assess the performance of local soils, geologic materials and selected media types. The experiment will also help identify parameter values such as nitrification, denitrification and sorption rates for native materials and other treatment media (e.g. biochar) that can be used for the development of effective subsurface or mound systems and for assessment of watershed scale impacts. To evaluate effects of temperature, the experiments will be conducted under ambient conditions at two different seasons (winter and summer).