In accordance with section three hundred seventeen, bids may be solicited from vendors who have been prequalified for the provision of a good, service or construction pursuant to section three hundred twenty-four by mailing notice to each prequalified vendor or, if special circumstances require, to a selected list of prequalified vendors. Award of the contract shall be made in accordance with the provisions of section three hundred thirteen of this chapter. A determination to employ selective solicitation for a particular procurement or for a particular category of procurement shall be made in writing by the agency and approved by the mayor; unless the mayor, upon adequate assurances of an agency's capacity to comply with procedural requirements in relation to this section, has determined that such approval is not required for an agency's contracts or particular categories of contracts.