(a) All contracts for construction work whose estimated cost will exceed $30,000 shall be let to the lowest responsible bidder after publication of notice for bids. Notice for bids shall be published once in a newspaper published and having general circulation in the township, if there is one. If there is no such newspaper, notice for bids shall be published in a newspaper published and having general circulation in the county. Notice for bids shall be published at least 10 days before the date set for receiving bids. Bids shall be opened and publicly read, and an award shall be made to the lowest responsible bidder within 15 days after the receipt of bids.
     (b) This Section shall not apply to engineering, legal, or other professional services, but it shall apply to the purchase of equipment unless the township board, by a resolution adopted by a three-fourths vote, determines that it is for the best interests of the township that advertising for bids for the equipment be dispensed with.