2006 – A Summary Of Major Dam Safety Deficiencies Identified By The Initial U.S. Army Corps Of Engineers’ Screening Portfolio Risk Assessment Program

Jeffrey A. Schaefer, Ph.D., P.E., P.G. and David M. Schaaf, P.E.

In 2005 the U.S. Army Corps of Engineers (USACE) developed and implemented a Screening Portfolio Risk Assessment (SPRA) process for Dam Safety. The screening process considered loading frequency, an engineering rating to estimate a relative probability of failure, and both human life and economic consequences of failure. The results were utilized as a tool to help prioritize funding for dam safety modification projects and required studies. Three multidisciplinary cadres evaluated what was considered the worst 10% of the USACE’s dam projects in 2005 and the next worst 10% in 2006. The dams evaluated included flood control, navigation, and multi-purpose dams. Approximately seventy facilities were evaluated each year.

As a result of the aging of the USACE’s dam portfolio and the state of the art at the time of design and construction (mostly 1940’s-50’s), significant dam safety deficiencies exist at many USACE dams. This paper summarizes the major deficiencies identified from the SPRA process. Examples, including foundation seepage, karst development, embankment stability, gate deterioration, liquefiable foundations, and inadequate spillway capacity are provided along with discussion on which deficiencies contribute the greatest risk.