55 ILCS 5/5-32036
Notice shall be given by the Committee that bids will be received for the construction of such an improvement, either as a whole or in such sections as the Committee shall specify in its notice, in accordance with the ordinance therefor. This notice shall state the time of opening of the bids, and shall further state where the specifications for the improvement are to be found, and whether the contracts are to be paid in cash or in bonds, and if in bonds, then the rate of interest the vouchers or bonds shall draw. The notice shall be published at least twice, not more than 30 nor less than 15 days in advance of the opening of the bids, in one or more newspapers published in the county as designated by the Committee in an order entered in its records, or if no newspaper is published therein then in one or more newspapers with a general circulation within the county.
Proposals or bids may be made either for the work as a whole or for specified sections thereof. All proposals or bids shall be accompanied by cash, or by a check payable to the order of the Committee, certified by a responsible bank, for an amount which shall not be less than 10% of the aggregate of the proposal, or by a bid bond, for an amount which shall not be less than 10% of the aggregate of the proposal. These proposals or bids shall be delivered to the Committee. That committee, in open session, at the time and place fixed in the specified notice, shall examine and publicly declare the proposal or bids. However, no proposal or bids shall be considered unless accompanied by such a check or cash.
55 ILCS 5/5-32036