Posted on March 10, 2020
WINONA — With the levels of river discharge up, the amount of material floating down the Mississippi River — and dropping to the bottom of the river — is up as well.
That means more material dredged up each year, said Paul Machajewski, a dredged material manager for the U.S. Army Corps of Engineers, St. Paul District.
“It’s doubled,” Machajewski said, pointing to the historic average of dredge material removed from Pool 6, which runs from Lock and Dam No. 5A near the city of Goodview to Lock and Dam No. 6 downriver at Trempealeau, Wis. Dredging has gone from about 23,000 cubic yards of material a year to a recent 10-year average of 62,500 cubic yards.
Despite the increased amount of material dredged to maintain the 9-foot navigation channel for barge traffic, the city of Winona and surrounding areas have never really needed to worry about permanent storage of dredge material like the residents around Wabasha.
“Everything we’ve ever dredged here has gone to beneficial use,” Machajewski said. “The only thing that hasn’t, and that’s minimal, is sitting on the piles here.”
Pool 6 is expected to produce 1.25 million cubic yards of dredge material over the next 20 years, the Corps estimates. Compared to other nearby pools, Pool 6 has seen its average dredging volume substantially increase over the last four decades, the Corps reports. The average annual dredging volume in the 2010s was 62,400 cubic yards, nearly five times the average from the period of 1981-2009.
Even with the increased amount of sand and silt, Machajewski said he’s hopeful projects requiring sand around the Winona area will continue to use everything the Corps pulls from the river bottom. However, the Corps does need to ensure that its temporary storage sites have enough capacity to hold the sand until it gets used each year.
“We’re working hand-in-hand with the city to come up with a solution,” he said. “We’re working close with the city staff.”
Winona City Administrator Steve Sarvi said that while the Corps has a mission to keep the channel open and navigable, the agency has worked with the city to find the best places to store sand. Still, he has a few concerns as the Corps continues to hear public comments through April 10 for the plan.
“There’s some environmental issues in the larger plan on Latsch Island,” Sarvi said. “(The plan) says it’s not a high-value wetland. I guess I’d like to know more about that.”
Sarvi said a group opposing the dredge material management plan has posted on social media a false representation of what the Corps’ use of Latsch Island might look like, but the city still has concerns about what the island might look like from the city’s riverfront.
“There’s certainly an aesthetic piece to it that we want to maintain, and we think the buffering might be beneficial,” he said.
The city plans to form a committee to continue working with the Corps on sand placement until the dredge material management plan is completed, however the city could vote to support the plan by the end of March or beginning of April.
Machajewski said he’s hopeful to see the sand continue to be used, and projects ranging from new uses such as Fastenal’s new downtown building or construction along the city’s east end, or continuing projects such as road construction or salt-and-sanding operations in the winter should fill the need.
“The concern would be to keep the beneficial use keeping up with the amount of sand we’re bringing in on an annual basis,” Machajewski said.
Source: postbulletin.com
