85. Unless it involves an expenditure of less than $50,000, and subject to any preferential provisions in the Agreement relating to the Crees, every contract for the performance of work or the supply of equipment or materials or the providing of services other than professional services shall not be awarded by the Council except after a call for public tenders. The Council shall establish, by by-law, the procedures and requirements relating to the calling of tenders and awarding of contracts.