It's Miller Time. The Tom Miller Dam Modernization Project

Tom Miller Dam is a 100+ year old concrete and masonry dam located on the Colorado River in Austin, Texas. The dam provides hydropower for central Texas and the reservoir (Lake Austin) serves as the sole source of water for the City of Austin. The high hazard dam was first constructed in 1890 and suffered two catastrophic failures prior to a major reconstruct in 1938. The recent modernization project, undertaken by the Lower Colorado River Authority, includes assessment of the foundation and sliding stability of the dam utilizing current flood projections that are substantially higher than the original and subsequent reconstruction design levels.

This paper/presentation contains an overview of the colorful and somewhat tragic history of the dam, and the geotechnical/geological investigative techniques used for the sliding stability assessment. In addition to traditional exploratory and testing methods (core drilling, packer pressure testing, etc.), down-hole video camera imaging and cross-hole seismic testing were used to evaluate the dam and rock foundation materials. Back-calculation analyses of the two failures were also utilized to aid in the interpretation of the sliding parameters. The comprehensive investigation concluded that only part of the dam required stabilization, thus saving the LCRA millions of dollars based on preliminary assessments of full stabilization. The stabilization procedures include high capacity post tension rock anchors, concrete infilling, and stitch anchors. Construction began in June, 2003 and is expected to be complete in September, 2004. 13 pp., 1 table, 16 figures, 3 references.