Soil-bentonite slurry cutoff walls are used to prevent the movement of contaminated groundwater. Defects which reduce the overall efficacy of the wall may become present during construction or the aging of the wall. In this research, we use ground penetrating radar (GPR) and electrical resistivity (ER) as non-invasive and minimally invasive geophysical techniques, respectively, in an attempt to characterize the shallow portions of a soil bentonite slurry cutoff wall and detect defects within the wall. Sandbags and a limestone block were placed within the northernmost section of an experimental soil-bentonite slurry cutoff wall in Montandon, PA to represent defects that could lead to high hydraulic conductivity within the wall. GPR surveys were collected along the wall and surrounding area to investigate the unsaturated zone and determine if GPR could reliably observe the elevation difference of the water table across the wall. GPR estimates of the soil water content (SWC) differences were also evaluated as a possible way to determine the location of more permeable zones (e.g., fractures) within the unsaturated zone of the cutoff wall. The apparent resistivity of both defect and non-defect locations in the wall were collected using long point-source electrodes in Wenner and dipole-dipole arrays at various depths, as well as non-traditional geometries. The point electrodes inserted into the wall at a 1 meter a-spacing indicate a higher apparent resistivity associated at defect locations relative to at the non-defect locations. Additionally, the mise-a-la-masse method with in-wall electrodes and surface electrodes was used to measure the change in voltage along the wall and the surrounding areas in both defect and non-defect locations. We will discuss how data from the individual or concurrent use of these two methods may help locate potential defects within soil-bentonite slurry cutoff walls. The ability to reliably detect defects within slurry walls using non-invasive or minimally invasive techniques will help retain the integrity of the wall, allow for quality assurance for construction companies, and monitor walls throughout their life at a low cost.