Dam Seepage Investigation of an Earthfill Dam in Warren County, Missouri Using Geophysical Methods

Electrical resistivity tomography (ERT), induced polarization (IP) and spontaneous potential (SP) data were acquired across and in proximity to a leaking earth-fill dam (Wolf Creek dam) in Warren County, Missouri. The objectives were to identify and map probable seepage pathways through the dam and to determine if the outlet works drainage pipe used in the construction of the dam was leaking. On the basis of the integrated interpretation of the acquired geophysical data two probable seepage pathways through the leaking earth-fill dam were identified and mapped. These two pathways are referred to as the Groin Leak and Water Fall Leak, respectively. The Groin Leak and Water Fall Leak seepage pathways are both characterized by relatively low resistivity and low chargeability. It is also concluded that there is high probability that water is leaking from the downstream end of the outlet works drainage pipe. The interpreted drainage pipe leak (Outlet works Leak) is characterized by relatively low resistivity, high chargeability and negative self-potential values.