Webinar: Review of the 1938 Construction Slide at Fort Peck Dam

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 had 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.

As a result of this slope failure, the original design Board of Consultants was expanded to assess the cause of the failure, and review options for completing the dam construction including repairs in the failure area. There were many lessons learned, contributing to industry-wide changes . The failure as well as other performance factors during first filling of the reservoir altered the U.S. Army Corps of Engineers (USACE) design and construction practices significantly. The failure has also imparted important lessons to the U.S. community of practice for dams and levees and continues to be studied today in an effort to better understand the shear strength of contractive, liquefiable soils.

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. 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. includes a discussion of evolution of technology related to the shear strength of shales, and the liquefaction of sands.