Rough River Dam Safety Modification Project Evolution

This paper is a case study documenting how the Rough River Dam Safety Modification Project evolved over time. Rough River Dam is an embankment dam located in west-central Kentucky that is owned and operated by the U.S. Army Corps of Engineers (USACE) for flood risk management. The project has a right abutment cut-and-cover outlet conduit founded upon karstic limestone. In 2012, a Dam Safety Modification Report (DSMR) was completed that identified multiple internal erosion-related potential failure modes requiring mitigation. The DSMR recommended a multi-phased approach. The Phase I project included construction of a work platform in order to perform exploratory drilling and grouting for two partial grout lines. The Phase II project was to consist of grout line completion, construction of a full-length cutoff wall over and around the existing outlet conduit, grouting within the outlet conduit, and construction of a downstream filter. Based on encountered conditions, the Phase I grouting contract was modified to complete both partial grout lines for slurry control prior to cutoff wall construction. During design of the Phase II cutoff wall, the existing outlet conduit was determined to be structurally inadequate to support the cutoff wall. A Supplemental DSMR recommended a new left abutment outlet works to permit the existing conduit to be severed and to allow for construction of the full cutoff wall across the dam foundation. The Phase II design was completed in the fall of 2021. This paper summarizes the key information, findings, and decisions that informed the final direction of the project.