DECATUR — Crews are set to begin work in the coming weeks on the last leg of the $91 million dredging project in Lake Decatur, moving into the basin north of the William Street Bridge, according to City Engineer Paul Caswell.
"(Workers) will still have a lot of cleanup and breakdown the following year, but the hope is to complete the dredging this year so they don't have to winter over again," Caswell said.
It's a milestone years in the making for contractor Great Lakes Dredge & Dock, which started the work in fall 2014. After a severe drought hit the region in 2012, leading to the most severe water restrictions in Decatur's history, city officials launched what was described as their largest public works project since the lake was built in the 1920s to increase the lake's storage capacity. To fund the work, the Decatur City Council voted in April 2013 to more than double water rates over three years, raising money to pay off bonds to cover the cost of the project and other improvements to the water system.
The lake's water is a critical component of grain processing at nearby facilities run by Archer Daniels Midland Co. and Tate & Lyle North America, Inc. While it provides drinking water for residents in Decatur and Mount Zion, just 10 percent of the city's water supply is used by residences.
Once the project is finished, officials have said, the lake's capacity will be 30 percent larger than when work first began — equal to an additional 52 days of water supply.
"They are ahead of schedule, but ... the tail end of the last year, that had to stop a little bit sooner due to capacity issues to where the sediment is," City Manager Tim Gleason said.
The dredge machines are essentially vacuuming tons of sediment out of the lake floor, pumping it through miles of pipes running along the lake bottom into a 523-acre site off Angle Crossing Road in Oakley. The basin was full of sediment from previous, smaller-scale dredging efforts, and crews from subcontractor Terra Contracting Services spent more than two years in the early part of the project raising the berms, or barriers, around the site to increase its capacity.
But more work at that site may be needed. The sediment is not settling and compacting at a normal rate because of wet weather conditions, Gleason said. "That has presented a minor problem ... but we're planning to add to the height of the berm," he said.
The benefits of the project have already been realized, when last summer almost 13 percent of the state experienced a moderate drought, mainly across Central Illinois along the Interstate 72 corridor, from Missouri to Indiana.
With 42 days of water storage to the lake, Public Works Director Matt Newell said in November, the city was able to avoid implementing preliminary stages of water rationing. That would have resulted in the city requesting that all water customers voluntarily conserve water.
Where crews start up work this year will begin around the city's water main in the lake, Caswell said. Part of the contract with Great Lakes is to replace the main with a bigger pipe. The community’s need for water has increased since the 1960s when the original line was built.