70 ILCS 200/155-55
All contracts for sale of property of the value of more than $10,000 , or for a concession in or lease of property, including air rights, of the Authority for a term of more than one year, shall be awarded to the highest responsible bidder, after advertising for bids. All construction contracts and contracts for supplies, materials, equipment and services, when the expense thereof will exceed $10,000 , shall be let to the lowest responsible bidder, after advertising for bids, except: (1) when repair parts, accessories, equipment or services are required for equipment or services previously furnished or contracted for; (2) when the nature of the services required is such that competitive bidding is not in the best interest of the public, including, without limiting the generality of the foregoing, the services of accountants, architects, attorneys, engineers, financial advisors, investment bankers, physicians, superintendents of construction, and others possessing a high degree of skill; and (3) when services such as water, light, heat, power, telephone or telegraph are required.
All contracts involving less than $10,000 shall be let by competitive bidding to the lowest responsible bidder whenever possible, and in any event in a manner calculated to ensure the best interests of the public.
In determining the responsibility of any bidder, the Board may take into account the past record of dealings with the bidder, the bidder's experience, adequacy of equipment, and ability to complete performance within the time set, and other factors besides financial responsibility, but in no case shall any such contract be awarded to any other than the highest bidder (in case of sale, concession or lease) or the lowest bidder (in case of purchase or expenditure) unless authorized or approved by a vote of at least 5 of the members of the Board, and unless such action is accompanied by a statement in writing setting forth the reasons for not awarding the contract to the highest or lowest bidder, as the case may be, which statement shall be kept on file in the principal office of the Authority and open to public inspection.
Members of the Board, officers and employees of the Authority, and their relatives within the fourth degree of consanguinity by the terms of the civil law, are forbidden to be interested directly or indirectly in any contract for construction or maintenance work or for the delivery of materials, supplies or equipment.
The Board shall have the right to reject all bids and to readvertise for bids. If after any such advertisement no responsible and satisfactory bid, within the terms of the advertisement, shall be received, the Board may award such contract, without competitive bidding, provided that it shall not be less advantageous to the Authority than any valid bid received pursuant to advertisement.
The Board shall adopt rules and regulations to carry into effect the provisions of this Section.
70 ILCS 200/155-55