No contract involving the expenditure of money or purchase order shall be made unless there is attached thereto the certificate of the Manager that the amount required to meet the obligation has been appropriated for such purpose and is available or in the process of collection. Notwithstanding the above provision, however, provisions of general law regarding appropriations and availability of funds shall govern as to contracts running beyond the fiscal year in which they are made and contracts paid in whole or in part by special assessment for improvements.
All purchases and contracts shall comply with general statutory law in regard to the necessity of advertising and bids in relation to purchases and contracts above the authorized limits.