The county council shall by ordinance establish procedures for purchasing supplies, services, materials and equipment, the awarding of contracts, the processing of claims, and the sale or refunding of bonds. The ordinance shall provide when bids shall be required and how invitations for bids shall be advertised.

All purchases, contracts and bonds subject to bid procedures shall be advertised and, unless all bids are rejected, shall be awarded on the basis of sealed bidding to the lowest responsible bidder.