DSM Saves the Dam

The Miami Conservancy District built five flood control dams after the catastrophic flood of 1913 in Dayton, Ohio. Lockington Dam was one of these five hydraulic fill structures. The Ohio State Department of Natural Resources (ODNR) issued new regulations in 1981 requiring that design flood for class I dams be considered equal to the Probable Maximum Flood (PMF). Flood routing studies performed for the PMF calculated inflow indicated that the reservoir rose to the crest of the dam. Therefore, the existing dam core required extending to the crest level to maintain dam safety. The extension was constructed using a deep soil mix soil cement cutoff wall. This paper will describe the cutoff wall from conceptual design through to construction, including alternates considered, construction methods and data obtained, both prior to and during construction. While Deep Soil Mixing (DSM) has been used on contaminated sites as a method of containment and for dam foundations to decrease the risk of liquefaction, Lockington Dam represents one of the first applications as a conventional cutoff on an existing dam.