Posted on December 7, 2021
Nick-named “Old Banana Boat”
by Marc Krumholz
Congress authorized the 9-foot Navigation Channel to increase commerce on the river in 1930. Upon the project’s approval, the Corps of Engineers began constructing a series of 29 locks and dams from Minneapolis to St. Louis, creating the stairway of water for river traffic that exists today.
Since the river is constantly shifting its load of sand and sediment, in addition to tributaries contributing more along the way; it is necessary to remove the material from the bottom of the channel to prevent a closure to navigation. This process of underwater excavation is called dredging.
The St. Paul District operated three hydraulic dredges in the 1920s and ‘30s. The Vesuvius, Peelee and Cahaba were responsible for the majority of the dredging. Many million cubic yards of dredged material had to be removed from the river to establish and maintain the navigation channel and the old steam dredges were slow with the capability to move only 500,000 cubic yards of material during a season. A new dredge with a much bigger capability and modern equipment was needed to meet the challenge of maintaining the navigation channel.
Plans and specifications for a new more efficient hydraulic dredge started in 1935. The vessel was to be named after William A. Thompson (b. Dec. 16, 1854), who graduated from the University of Vermont with a degree in civil engineering in 1878 and entered federal service that same year with the Corps of Engineers. In 1896, he was appointed to the position of assistant engineer responsible for the improvements on the Upper Mississippi River.
Built by Dravo Corporation in Pittsburgh, Pennsylvania, the Dredge William A. Thompson was christened there in March 1937. A granddaughter of William Thompson broke the
traditional bottle on the hull. The new vessel arrived at the Corps’ Fountain City, Wisconsin, boatyard 14 days later.
The Dredge Thompson removed dredged material from the river much like a vacuum cleaner works. Its pipeline cutterhead sucked up the sand from the river bottom. She was capable of extracting 1,800 cubic yards per hour.
The Thompson was the biggest single piece of equipment used by the St. Paul District at the time. She was 267 feet long from the tip of the cutterhead to her stern. She was 48 feet wide and had a minimum bridge-clearing elevation of 52 feet, 9 inches. She had a 22-inch intake and 20-inch discharge pipe. The vessel could dredge to a depth of 26 feet and cut a channel 350 feet wide from one mooring.
In order to maintain a three-shift operation, the 1,370-ton dredge could carry up to 66 crew members. This allowed the vessel to dredge 24 hours a day, seven days a week. The Thompson normally dredged 1.5 to 2 million cubic yards each year. During her first 50 years of service, more than 100,000,000 cubic yards of material were removed from the navigation channel. This quantity would create a pyramid one square mile approximately and 300 feet high.
After a storied career, the Dredge Thompson was replaced by the Dredge William L. Goetz, in 2005. The Thompson continued to serve as a quarters boat until 2008. In 2012, the Thompson was sold to Community Development Alternatives, or CDA, in Prairie Du Chien, Wisconsin. She departed on her last voyage on June, 12, 2012, arriving at her new home the following day. The CDA is working to preserve the Thompson and her rich history of service on the Upper Mississippi River. The CDA is currently developing plans to convert the Dredge Thompson into a Museum of River Transportation.
12 The St. Paul Distict
