Lake County engineering staff told the Public Works and Transportation Committee on Oct. 8 that construction on the Winchester Road intersection at Illinois Route 83 requires additional soil remediation after crews excavated existing pavement and discovered an unanticipated area of unsuitable soil.

Shane Schneider, county engineer, said the project is about three-quarters complete on the south leg and that geotechnical borings done during design missed a large pocket of soft, peat-like material. Contractors will drive rammed aggregate piers to stabilize the soil. “They’re driving piers in the ground to stabilize the soil,” Schneider said. “Each column supports 3,000 pounds per square inch of pressure… those go down about 20 feet into the ground to a stronger soil.”

The committee approved a joint resolution appropriating $921,000 of quarter-percent sales-tax transportation funds and approving Change Order No. 4 in the amount of $1,294,769.65 to pay for the additional mitigation work. Schneider said the county has asked the Illinois Department of Transportation to cover 50% of the additional cost; IDOT gave verbal agreement and a written reimbursement agreement was expected to follow.

Timing and cost: the intersection remained closed at the time of the meeting, and county staff said work is still scheduled for completion this year unless another unforeseen issue arises. Schneider told the committee that contractors are holding unit prices from the original bid and that the county followed IDOT specifications for soil borings in the design phase; the pocket of bad soil was not discovered until pavement removal.

Committee members pressed staff on whether extra sampling or wider borings would reduce future change orders in areas with variable glacial soils. Schneider said the team followed IDOT-prescribed spacing for borings but agreed to review whether additional borings would be valuable in similar sites.

Outcome: The committee approved the appropriation and the change order; formal vote was recorded as carried.