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The Use of NMR Logging Measurements to Estimate Hydraulic Conductivity in Glacial Aquifers

The Place

Central Wisconsin

The Problem

The Glacial Aquifer System is the largest drinking water and public supply source in terms of aerial extent in the United States. This groundwater system is an important national water supply source, delivering water to 41 million people. Availability of water in this glacial system is often constrained by climatic conditions, poor water quality, the geologic setting, and by potential conflicts between current groundwater users and management priorities. The large aerial extent of the aquifer complicates most efforts to characterize the system. Given the aquifer’s extensive use as a public water supply, there is a need to characterize the aquifer’s properties to provide a scientific basis for groundwater management.

Our Approach

Nuclear magnetic resonance (NMR) is a geophysical method directly sensitive to water in the subsurface. With some empirical calibration, this method has been used to quantify aquifer parameters important for groundwater management, such as hydraulic conductivity (K). We proposed to use a combination of NMR and well-logging tools to quantify K in the Glacial Aquifer System. Futhermore, we will use the co-located data from the NMR and well-logging tools to explore the fundamental link between NMR measured parameters and K at two separate locations.

In May/June 2018 we conducted a two week field campaign in collaboration with the USGS and Kansas Geological Survey (KGS) in central Wisconsin. Two PVC-cased wells were installed to a depth of 66 ft (~20 m). At each location, NMR and a direct push permeameter (DPP) were used to measure K as a function of depth. A core sample was also collected at one location to be studied further in the laboratory. This field data is currently in the process of being analyzed.