After expiration of the period stated in the publications or other public announcements, the department shall evaluate statements of qualifications and performance data which have been submitted to the department. Discussions shall be conducted with no less than three firms regarding the required service. Where three firms cannot be found which could provide the required service, a full explanation including names and addresses of firms and individuals requested to submit proposals must be entered in the files. From the firms with which discussions are held, the department shall select no less than three, provided at least three firms submit proposals, in order of preference, based upon the established criteria, which are deemed to be the most highly qualified to provide the services required.