Advanced Applications of the Dissolved Oxygen Alteration Method

Detailed flow characterization in groundwater wells is important for water supply assessments, including the identification of water sources and evaluation of sustainability, discerning contamination sources and spreading, and in remediating contaminated groundwater. Despite advancements in groundwater flow characterization, its application remains limited primarily due to the high cost and logistical difficulty of conventional techniques. The series of applications described here are an expansion upon the dissolved oxygen alteration method, a borehole dilution technique originally developed by Chlebica and Robbins (2013) to locate transmissive fractures and decipher vertical borehole flow conditions in fractured crystalline bedrock wells, providing a qualitative assessment of in-well flow. The method involves bubbling air into a well using a porous polypropylene “bubbler”, then profiling the dissolved oxygen with time. Inflow zones are identified by the regions where DO concentrations decrease over time. Vertical movement is determined by the vertical movement of diluted low-DO water and shifts in the DO profile. This work expands on the original method by developing advanced applications in crystalline bedrock wells for quantifying vertical flow rate, identifying interconnecting fractures between wells, and aiding in the sampling of individual fractures. The method was also further developed for characterizing flow conditions in screened wells in porous media. These advanced applications provide a cost-effective and highly-sensitive alternative for characterizing flow in wells to aid in water supply and contamination assessments