Any public work or improvement may be executed either by contract or by the employment of the necessary labor and the purchase of the necessary supplies and materials directly by the City. Any public work or improvement executed directly by the City shall be authorized by the Council only after detailed estimates have been submitted by the department or office authorized to execute such work or improvement, and there shall be separate accounting as to each work or improvement so executed. All the contracts for public work or improvements shall be awarded to the lowest and best responsible bidder, after public advertisement and competition as may be prescribed by ordinance, but the City Manager shall have the power to reject any and all bids and advertise again. All advertisements as to such contracts shall contain a reservation of the foregoing right. Contracts entered into by the City shall be signed by the City Manager or by such other officer, or officers, of the City as the Council may by ordinance provide. (Amended 11-8-11)