Posted on July 18, 2022
Story by Patrick Moes
Maintaining the Mississippi River 9-foot Navigation Channel is one of the primary missions for the St. Paul District.
To maintain the channel, the district typically removes around 1 million cubic yards of sand every year. While the sand is a nuisance for the navigation chan- nel and the shippers moving bulk commodities to markets up and down the river, it’s a blessing for developers looking for free, clean material to raise land above the flood plain, said Paul Macha- jewski, St. Paul District dredged material manager.
Machajewski said his team within the district’s channels and har- bors branch recently worked with the city of La Crosse, Wisconsin, to support their efforts to elevate an area out of the flood plain. “In all, a local contractor removed around 200,000 cubic yards of river sand from our Brownsville, Minnesota, placement site and moved it to a site within The La Crosse beneficial use project is a big deal, said Mach- ajewski. “Typically, contractors will come in and take about 30- 40,000 cubic yards of material per year, the contractors for the La Crosse project are taking 3-5 times that amount.”
Getting general construction fill material for free is a win-win for the community and the Corps of Engineers, said Machajewski. The benefits come from the fact that the city doesn’t need to use their tax dollars on the sand while also being able to protect an area within their community from future flood threats. In addition to the benefits that the city receives, Machajewski said the Corps of Engineers receives significant benefits, too, by creating additional storage capacity for future dredging needs to maintain the navigation channel. He said he estimates that the La Crosse beneficial use project will generate an additional 4-5 years of future storage capacity.
Dan DeVaney, St. Paul District channel maintenance coordinator, said one of the key parts of the channel maintenance program is placing the material at specific…upland placement sites, or river sand resource centers, for communities to reuse the sand for a variety of purposes. “The material is ideal for use in winter road maintenance, construction site fill, or even general fill material for the local farming communities as cattle bedding,” said DeVaney.
Corps staff are exploring other options for placing river sand, too. Eric Hanson, St. Paul District senior ecologist and environmental planner, said he is a part of a team that is exploring the possibility of using agricultural fields near the Mississippi River as options for permanently plac- ing river sand removed from the navigation channel. He said they are looking at several methods that would use the river sand to improve the soil structure and function on poorly drained and semi-poorly drained agricultural lands with the end goal of im- proving overall crop production. Hanson said plans are currently in development, and the team hopes to test the concepts over the next 2-3 years to verify the hypothesis that incorporating river sand would improve agricultural production. “If successful,” Hanson said, “this study would open up tens of thousands and perhaps hundreds of thousands Dredging operations near La Crosse, Wisconsin, September 24, 2021. USACE photo by Patrick Moes of acres nationwide not previous- ly considered for the permanent placement of river sand, and provide an eco-friendly, cost-effective and collaborative solution to managing river sand.”
Machajewski said the potential for agricultural field placement is just one area where the team is looking for future solutions to the annual need to place river sand removed from the navigation channel. He said the team continues exploring opportunities and have started looking at blending it with soils for use around new road construction to improve drainage near roads.
