Foundation Designs for a 345 kV Transmission Line Constructed in the Lakebed of Glacial Lake Agassiz

摘要

The Fargo - Saint Cloud 345 kV transmission line project led by Xcel Energy as part of the CapX2020 transmission expansion initiative includes about 52 miles containing 284 tubular steel structures located in the lakebed of Glacial Lake Agassiz (GLA) in northwest Minnesota and eastern North Dakota. GLA was an immense glacial lake. It was larger than all of the Great Lakes combined and held more water than all lakes in the world today. When GLA drained about 8,500 years ago, it left deep soft clay deposits that can create a challenge for foundation installation and can introduce potential for long-term creep in foundation deflections. A study, which included full scale constructability testing, was conducted to evaluate appropriate design and construction methods to address these concerns. This paper will describe the study and the design and construction methods used to install foundations in the deep soft clay deposits of GLA.