Upon a determination by the Community Development Director and City Engineer that the lots proposed for merger are legal lots, that the subject lots are under common ownership, and that all public improvements normally required for parcel map approval have either been installed and accepted or will be required as part of a future entitlement for use or development of the subject lot(s), a certificate of lot merger shall be prepared. Said certificate shall describe the new exterior boundary of the lot after merger and shall be recorded in the office of the County Recorder.