70 ILCS 2205/23
Except as otherwise provided in this Section, all contracts for work to be done and supplies and materials to be purchased by the sanitary district, the expense of which will exceed $10,000 shall be let to the lowest responsible bidder therefor, upon not less than 14 days' public notice of the terms and conditions upon which the contract is to be let, having been given by publication in a newspaper of general circulation published in the district, and the board of trustees may reject any and all bids and readvertise. All purchases or sales of $10,000 or less may be made in the open market without publication in a newspaper as above provided, but whenever practical shall be based on at least 3 competitive bids.
Where the board of trustees declares, by a 2/3 vote of those elected, that there exists an emergency affecting the public health or safety, contracts totaling not more than $40,000 may be let to the extent necessary to resolve such emergency without public advertisement or competitive bidding. The ordinance or resolution embodying the emergency declaration shall contain the date upon which such emergency will terminate. The board of trustees may extend the termination date if in its judgment the circumstances so require. A full written account of the emergency, together with a requisition for the materials, supplies, labor or equipment required therefor shall be submitted immediately upon completion and shall be open to public inspection for a period of at least one year subsequent to the date of such emergency purchase.
No person may be employed on the work except citizens of the United States, or those who in good faith have declared their intention to become citizens, and 8 hours constitutes a day's work.
70 ILCS 2205/23