SECTION 5.10 PURCHASES AND CONTRACTS.
   (a)    Competitive Bidding. Before the City Manager makes any purchase of, or contract for supplies, materials or equipment costing in excess of one thousand dollars ($1,000.00), or such higher amount as may be determined by ordinance, he/she shall take competitive bids under such rules and regulations, and with such exceptions as the Council shall prescribe by ordinance.
 
   (b)    Emergency Purchases and Expenditures. In case of emergency, purchases and expenditures may be made without competition if the Council authorizes a purchase or expenditure by resolution. In such cases a copy of the order issued shall be filed with the City Clerk, together with a certificate by the City Manager, stating the facts of the emergency. A copy of his/her certificate shall also be attached to and filed with the voucher covering payment for supplies, equipment and services.
   (c)    Contracts for City Improvements. Any City improvement, except emergency purchases and expenditures provided for in Section 5.10 (b), costing in excess of one thousand dollars ($1,000.00), or such higher amount as may be determined by ordinance, 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 shall be awarded to the lowest and best bidder after such public notice and competition as may be prescribed by ordinance, provided the City Manager shall have the power to reject all bids and advertise again. Alterations in any contract may be made when authorized by the Council upon the written recommendation of the City Manager.
 
   (d)    Accounting Control of Purchases. All purchases made and contracts executed by the City Manager shall be pursuant to a written requisition from the head of the division, department or agency whose appropriation will be charged, and no contract or order shall be issued to any vendor unless and until the Director of Finance certifies that there is to the credit of such division, department or agency a sufficient unencumbered appropriations balance to pay for the supplies, materials, equipment or contractual services for which the contract or order is to be issued.
   (e)    No Contract Executed Until Bond or Note Ordinance Effective. No contract shall be executed for the acquisition of any property or the construction of any improvement or betterment to be financed by the issuance of bonds until the ordinance authorizing the issuance of such bonds, or notes in anticipation of the issuance of such bonds, shall have taken effect and any contract executed before such day shall be unenforceable in any court of law.