Monitoring and alleviating AAR growth at Santeetlah Dam

Santeetlah Dam, originally constructed 1926-1928, has undergone periodic modifications throughout its operating history. The concrete gravity dam with integral arch section has been subjected to alkali- aggregate reactivity (AAR), which has caused localized base movement, overall cracking, leakage and deterioration. Many programs have been initiated to curtail the impacts of the concrete growth, including the installation of post tensioned rock anchors and through bolts, concrete additions to anchor sections of the dam, comprehensive grouting programs, and historic slot cutting programs. Based on the findings from these programs, data from the over 400 manual and automated instruments installed in the dam, and a predictive three dimensional finite element model of the dam, a new slot cut was planned, and successfully cut during the late fall and winter of 2012/2013. This article discusses the practice of monitoring the state of the AAR growth at the dam, as well as the concrete removal techniques employed during the most recent slot cutting effort.