Abstract:
Rough River Dam is a high hazard flood risk management embankment dam, owned and operated by the US Army Corps of Engineers (USACE), located in west-central Kentucky. In 2005, Rough River Dam was classified as a “ High Urgency” project due to concerns with untreated karstic bedrock within the dam foundation. The dam spans an incised valley flanked by upper and lower karst formations. The dam’ s outlet works is founded upon the lower karst formation at the base of the right abutment. Two high pool events between 2008 and 2011 triggered observable changes in instrumentation trends and, along with anomalies in the performance history, were interpreted to represent internal erosion near the outlet conduit. A series of automated piezometers were installed in 2012 which confirmed significant tailwater influence extending across the dam centerline. The project was approved for implementation of an exploratory grouting program intended to define the foundation conditions and inform the design for a future cutoff wall. A construction contract to install two partial grout lines along the dam crest was awarded in 2015, modified in 2016 after grout was found exiting into the retreat channel, and completed in 2017. The drilling and grouting at Rough River Dam represented the culmination and execution of several key drilling and grouting Lesson’ s Learned from USACE and across Industry. The grouting utilized down-hole instrumented packers for all grouting operations, complied with updated USACE requirements for drilling in earthen embankments and grouting in dam foundations, and included an ADAS with over 100 instruments. The project confirmed the need for a cut-off wall and successfully installed 328 production grout holes requiring 40, 000 linear feet of drilling and a total of 212, 763 gallons grout. This paper will detail the history of the Rough River Dam foundation, instrumentation, exploratory grouting, and postconstruction performance.