Review of 1938 Construction Slide at Fort Peck Dam: Download

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This webinar will review the 1938 construction failure of the upstream slope of Fort Peck Dam, Montana. The failure began at about 1:15 PM on September 22, 1938 as the construction work progressed to within 20 feet of the final dam crest elevation. One hundred eighty men were working in the area. Thirty-four men were injured. Eight men lost their lives, six of whom were never found and are buried somewhere in the dam.

This webinar will be presented in two parts. The first part will cover the background of the project through the reconstruction of dam in the area where the slide occurred and the early performance of the dam following first filling of the reservoir. Part II explores the broader technology and human factors that influenced the design and post failure investigation, including the controversies that the expanded Board of Consultants encountered in preparing a report on the cause of failure and in reviewing the redesign of the portion of the dam that failed. This part begins with a discussion of the differences of opinions about technical matters that were revealed in the project literature. It presents a summary of the state of the practice at the time of design and construction, and briefly traces technology advances during the next 40 years following the slide. This includes a discussion of evolution of technology related to the shear strength of shales, and the liquefaction of sands.

Key Takeaways:

Liquefaction and clay shale technology and failure mode timelines.
Taking action when distress indicators appear.
Importance of qualifications and experience of engineers in responsible charge of dams.
Key factors contributing to stability related failure mode development.

Keith A. Ferguson, P.E.,DWRE

Dam and Hydraulic Structure Practice Director

HDR Engineering, Inc.

Mr. Ferguson has over 44 years of planning, design, and construction experience on over 160 dams, levee, spillways, outlet works, canals, tunnels, and tailing impoundment projects across the US and internationally. He holds Bachelor and Master of Science degrees from the University of Colorado in civil and geotechnical engineering and is a registered professional engineer in 18 states. He is a recognized leader in dam safety, risk analysis, seepage and stability analyses, seismic response evaluations for embankment and concrete dams, in rock mechanics, and in design of embankment, roller compacted concrete, and rockfill dams. He was chair of the ASDSO Dam Safety Journal Editorial Committee from 2008 to 2013. He has been a member of the ASDSO Advisory Committee for over 20 years and is an active participant in the ASDSO Dam Failures and Incidents Committee. He recently completed a 7-year term as director, including a 2-year term as president, of the United States Society on Dams (USSD). He previously served as chair of the USSD Advocacy Initiative and the joint USSD Advocacy, Communication, and Public Awareness Committee from 2015 to early 2020. He served as chair of the USSD History Committee from 2015 to 2020 and is actively promoting the importance of understanding the historical context of major dam failures and incidents and the development of dam safety technology. He is a principal professional associate and dam and hydraulic structure practice director for HDR Engineering, Inc.