DECATUR — In a region married to industry and marred by drought, how much is water worth?
The Decatur City Council will soon tackle the question as it considers an $89.3 million contract with a dredging firm that promises to restore roughly 30 percent of Lake Decatur’s capacity by removing sediment that has collected on the lake bottom.
Officials hailed it as one of the largest projects the city has undertaken and one of the most vital to its future. They acknowledged, however, that residents might experience some sticker shock.
“It’s an enormous investment in our water system and an enormous improvement in the capacity of the lake,” City Manager Ryan McCrady said. “We know it’s a big number; $90 million is a big number to anybody, but I also think it’s very important that we do it.”
McCrady, Mayor Mike McElroy, Director of Water Management Keith Alexander and Director of Finance Gregg Zientara reviewed details of the proposal with the Herald & Review editorial board Wednesday.
The city selected Great Lakes Dredge & Dock, which was the low bidder in a months-long process of searching for a firm to dredge Basins 1, 2, 3 and 4. The project also would increase the capacity of a 523-acre site in Oakley Township that stores sediment pumped out from the lake.
The council is expected to discuss the contract in a study session at its meeting Tuesday but will not vote on the measure that night.
Council members took a major step toward the project last year when they approved a series of water rate increases meant to fund improvements to the city’s water system. The push came after severe drought in 2012 forced Decatur into mandatory water restrictions that temporarily closed some businesses, including car washes.
Dredging was always intended to be the most costly portion of the enhancements. The city would pay for the project by selling bonds over several years, with the debt set to be paid off completely in 2039.
“There will be no additional adjustment in water rates to be able to pay for this project. This was the plan all along,” McCrady said.
Had the project been executed before the 2012 drought, Alexander said the city might never have needed to turn to mandatory water restrictions.
The lake’s current capacity is 22,452 acre feet, and the project would remove an additional 6,655 acre feet. One acre foot is the equivalent of about 326,000 gallons of material.
Such a long-term commitment to the water supply could show businesses that Decatur is serious about preserving its resources, McElroy said.
“Certainly, anybody that’s doing business or looking to do business is really going to look at this and say, ‘Hey, they’ve got their act together. They’re doing everything that they can to solve a huge problem that they had the year before,’” he said.
The basins targeted in this project have not been dredged since the lake was built in the early 1920s. Previous dredging tackled Basins 5 and 6, but this contract would dwarf them in cost and scope.
Great Lakes could begin work on the Oakley site when weather allows, with dredging to start once that work is completed. The project is expected to last five to six years.
The contract does not require Great Lakes, which performed the dredging of Basin 6 in 2010 and 2011, to use local labor. However, city officials said the company has assured them it will employ many local people, particularly for work on the sediment storage site.
Officials said they considered alternate bids that would have reduced the scope of the project. Ultimately, they found dredging all four basins at once would cost the least per unit at $8.42 per cubic yard of material.
By contrast, dredging just three basins would cost $8.79 per cubic yard, with a total price tag of $86.7 million. Dredging two basins would cost $72.4 million, or $10.19 per cubic yard.
“It’s easy to focus on the overall cost and to probably move forward and say, ‘Let’s do the cheapest one right now, and let’s do the rest of them later.’ The problem with doing that is that it’s not the most efficient way to do it,” McCrady said.
As part of the project, the contractor would create two “sediment traps” near the Big Creek and Sand Creek arms of the lake. A sediment trap is an area that is deeper than the surrounding lake bottom, allowing sediment to sink as water passes through.
A sediment trap was also dredged in Basin 6 in 2011. The contractor would clean out that area at the conclusion of this project, Alexander said.
In the future, the city would be able to clean the sediment traps, rather than dredging an entire basin again.
“You’ll need a much smaller dredge,” Alexander said. “It’ll be there for a smaller time period, and it’ll be removing a much smaller quantity of material than the last three dredging projects.”
Additionally, the city already invests money in projects that aim to reduce the amount of sediment that gets into the lake. The Macon County Soil and Water Conservation District and Agricultural Watershed Institute have both received city funds for that purpose, Alexander said.
The watershed area for Lake Decatur is 925 square miles.
“That’s a big area to try to control as far as erosion and sediment goes. If it rains anywhere between here and Champaign, the lake sometimes sees a benefit from that,” McCrady said.