In the case of any contract for Services wherein motor bus service is to be rendered to the general public on any facility owned by the City, or in the case of any contract for the transportation within the boundaries of the City of any Commodities owned or in the possession of the City, the Purchaser, on recommendation of the department head concerned and approval of the Mayor or the Mayor’s designee provided that the designee is not the department head of the department concerned or the board or commission in charge of such department upon the ground that the public interest would be best served by requiring the inclusion of such a provision in the contract, may require that any person performing labor thereunder shall be paid not less than the highest general prevailing rate of wages, including fringe benefits or the matching equivalents thereof, paid in private employment for similar work in the area in which the contract is being performed, as determined by the Civil Service Commission; provided, however, if such a provision is to be included in the contract the notice inviting offers under Section 102.2 of this Code must call attention of Offerors to the requirements of said provision.