Levee upgrades continue
Outside of Cahokia, south of Levin Drive, workers using heavy equipment meticulously lower and seal into place 8-foot-long pieces, 36-inch in diameter, concrete pipes 25 feet below the surface.
It’s a long process that is repeated more than 900 times as workers install a 2,000-foot long pipe that will be used to move water into the adjacent Dead Creek that flows into the Mississippi River, while keeping water away from properties.
“We have great operators. ... We’ve had great support from the labor unions and craftsmen they’ve sent out to do the work,” said Kevin Williams, construction manager for Amec Foster Wheeler, the engineering firm overseeing the projects for the Southwestern Illinois Flood Prevention District Council.
So far the district council has completed about 85 percent of the construction work needed to bring the levees to a 100-year flood protection level. That work is expected to be completed in 2017.
“The vast majority of levee improvements we’re doing are for under seepage,” said Randy Cook, engineer for Amec Foster Wheeler. “A lot of people here the word levy and think we’re raising the levees. That’s not the case here ... Once we cover (the improvements) up, we’re hoping we’ll never see them and they’re out of the way.”
Madison, Monroe and St. Clair counties, which make up the Southwestern Illinois Flood Prevention District Council, set out to make these improvements and ultimately work toward a 500-year-flood protection level when Federal Emergency Management Agency was planning to de-certify the levees, which would have led to higher flood insurance rates.
To help pay for these levee improvements, the county boards in St. Clair, Madison and Monroe counties passed a quarter-cent sales tax.
The vast majority of levee improvements we’re doing are for under seepage. A lot of people here the word levy and think we’re raising the levees. That’s not the case here... Once we cover (the improvements) up, we’re hoping we’ll never see them and they’re out of the way.
Randy Cook, engineer for Amec Foster Wheeler
At the Cahokia-area work location, sandy soil is prevalent and water has an easier time flowing through, Cook said.
“Sandy soil is a problem,” Cook said. “Water moves faster through sandy soil than through clay.”
This particular project is expected to be completed in the spring, but if spring floods become an issue, the work may continue into the summer, Cook said.
But the work is mainly taking place in the winter, when the temperatures have dropped.
“There’s only certain times of the year we could work because of the river. If the ground water is too high, we can’t excavate here,” Cook said. “Winter is the ideal time. Historically, it’s when the river is low. Last winter was abnormally high. Last year we had floods in December, so that delayed a lot of construction.”
Cook said a lot of the work that is going on now was originally planned for last winter.
“It’s just taken that long for the river to come down,” Cook said.
Cook said the relief wells and the pipe being installed to carry water back to the creek are important to the entire system.
“It’s meant to protect the whole levee system. If there’s a break right here, it affects all the way to Granite City,” Cook said. “A breach here would have affects all the way to East St. Louis, Madison, Venice, (and) obviously Cahokia here.”
The district council also just recently approved storm sewer work in East St. Louis and two new sluice gates, which help control water flow, in Prairie DuPont area, for just under $700,000. The work is part of the district council’s efforts to reach the 100-year flood protection level.
The district council also just recently approved storm sewer work in East St. Louis and the installation of two new gates to help control water flow in Prairie DuPont area, for just under $700,000, Cook said. The work is part of the district council’s efforts to reach the 100-year flood protection level.
In East St. Louis there is a concrete sewer that runs under a levee that has leaks and needs to be rehabilitated. The 126-inch in diameter sewer, which was built before the 1950s, has outlived its life span, Cook said.
“The typical life span that we design for is a 50-year life,” Cook said.
The two gates that are being replaced are from the 1950s or ’60s and are malfunctioning, Cook said.
A lot of the corps of engineers design criteria for these levies was dated back to the 1950s, Cook said. That design criteria has changed and has improved over the years, he added.
“We don’t think they provide adequate protection anymore under the new criteria. Not necessarily because of failed maintenance or anything, but we know more about engineering, geotechnical engineering now, than we did in the 1950s. With the new criteria, we don’t think they’ll protect,” Cook said.
With the 100-year flood protection level nearly complete, work on the 500-year flood protection level is in the planning stages.
We hope to expend the money we have and hope the corps gets sufficient funds over the next several years.
Chuck Etwert, chief supervisor of Construction and the Works for the Southwestern Illinois Flood Prevention District Council
Engineering and design work for the 500-year-flood protection is underway, and is expected to be completed in late summer or early fall, said Chuck Etwert, chief supervisor of construction and the works for the district council. Actual construction projects on bringing levees to a 500-year flood protection level could be under contract by early 2018, he added.
The Flood Prevention District Council will pay for 35 percent of the costs of bringing the levees to a 500-year level through work-in-kind credit; the U.S. Army Corps of Engineers will pay for 65 percent of the work, when it has projects funded, Etwert said.
He said if everything goes perfectly where the river stayed low enough and the Corps of Engineers receives enough funding from Congress, the projects to bring the levees to the 500-year flood protection level could be completed in 2024.
“We hope to (spend) the money we have and hope the corps gets sufficient funds over the next several years,” Etwert said.