Ala. Code § 11-44C-71
Any city improvement costing more than $2,000.00 shall be executed by contract except where such improvement is authorized by the council to be executed directly by a city department in conformity with detailed plans, specifications and estimates. All such contracts for more than $2,000.00 shall be awarded to the lowest responsible bidder after such public notice and competition as may be prescribed by resolution or ordinance; provided, however, the mayor shall have the power to reject all bids and advertise again. Alteration in any contract may be made when authorized by the council upon the written recommendation of the mayor. Nothing in this chapter shall be construed to supersede or nullify provisions of state law requiring or governing competitive bidding.
Ala. Code § 11-44C-71 (1975)