BELLEVILLE — The City Council voted Monday to approve an extra $140,000 to clear muck and debris from the site of Kimball Plaza at Bicentennial Park.

The muck was found in the area of the parking lot and roadway leading to the proposed park, which is about 40 acres off 20th Street at the old Angler's Club.

The park is being developed with plans to be open by the city's 200th anniversary in 2014.

Contractor Jason Mettler, of Mettler Development, said the "unsuitable material" is from an old creek bed that goes for 8,000 yards, and is 6 feet deep in some areas and up to 12 feet deep elsewhere.

Workers will remove, dry and reuse the moist soil with up to 6,000 tons of rock to achieve stability. Workers will use the minimum amount of rock necessary, so the estimated figure is for the "worst case scenario," Mettler said.

Aldermen voted 10-5 to approve the extra work. Ward 2 Alderwoman Melinda Hult was absent.

Aldermen who voted "no" were: Ward 4 Aldermen Dean Hardt and Tim Carpenter, Ward 5 Alderman Joe Hayden, and Ward 7 Alderwoman Lillian Schneider and Ward 8 Alderman Joe Orlet.

Hardt asked whether a watershed study revealed the issue.

Geri Boyer, of Kaskaskia Engineering, said the area was covered in trees before developers cleared the land and there was no indication of any problems. Crews have since checked other parts of the park where there will be light structures, like the restrooms and gazebos, and those areas are fine.

Carpenter asked whether engineers could redesign the roadway to avoid the muck.

City Engineer Tim Gregowicz a redesign of the park would need state approval, delaying the project. Also, there isn't much leeway because of the existing creek.

Schneider and Orlet said they were concerned about how quickly aldermen learned of the problem, got a cost estimate and had to vote on the issue.

Hayden asked why the mayor didn't share the information with aldermen right away.

Eckert said he was not hiding anything. He was waiting for a cost estimate of the extra work.

Eckert said the city will use funds left over from the 17th Street project to pay for the extra work.

Ward 1 Alderman Ken Kinsella said the issue is a common construction problem and he has enough information to make a decision.

Ward 7 Alderman Phil Elmore said he did not support the city purchasing the park, but understands that change orders happen frequently in construction projects. Elmore said, for example, the sewer plant has had more than $1 million in change orders.

Elmore said he voted to approve the extra work because, otherwise, the city would be in jeopardy of finishing the plaza by Dec. 15 as stated in an agreement with the Kimball family.

Work on the park began in August after the City Council approved an $845,083 contract with Mettler for the first two phases. The contract will be paid for in part by tax increment financing funds and what's left of the $400,000 Kimball gift.

The first phase includes the plaza, parking lot, gazebo, sculpture, nature garden and trails. The park will be open to the public in spring 2013 after restrooms and lighting are installed in the second phase.

Contact reporter Jacqueline Lee at jlee@bnd.com or 239-2655. Follow her on Twitter at twitter.com/BNDBelleville.