70 ILCS 2605/11.7
All proposals to award purchase orders or contracts involving amounts in excess of the mandatory competitive bid threshold shall be published at least 12 calendar days in advance of the date announced for the receiving of bids, in a secular English language newspaper of general circulation in said sanitary district and shall be posted simultaneously on readily accessible bulletin boards in the principal office of the sanitary district. Nothing contained in this section shall be construed to prohibit the placing of additional advertisements in recognized trade journals. Advertisements for bids shall describe the character of the proposed contract or agreement in sufficient detail either in the advertisement itself or by reference to plans, specifications or other detail on file at the time of publication of the first announcement, to enable the bidders to know what their obligation will be. The advertisement shall also state the date, time and place assigned for the opening of bids. No bids shall be received at any time subsequent to the time indicated in the announcement; however, an extension of time may be granted for the opening of such bids upon publication in the same newspaper of general circulation in said sanitary district stating the date to which bid opening has been extended. The time of the extended bid opening shall not be less than 5 days after publication, Sundays and legal holidays excluded.
Cash, cashier's check or a certified check payable to the clerk and drawn upon a bank, as a deposit of good faith, in a reasonable amount not in excess of 10% of the contract amount, may be required of each bidder by the director of procurement and materials management on all bids involving amounts in excess of the mandatory competitive bid threshold. If a deposit is required, the advertisement for bids shall so specify. Instead of a deposit, the director of procurement and materials management may allow the use of a bid bond if the bond is issued by a surety company that is listed in the Federal Register and is authorized to do business in the State of Illinois.
70 ILCS 2605/11.7