All subpoenas issued under the provisions of this article may be served by any person who is not a party and who is not less than 18 years of age. When the witness is subpoenaed at the instance of the finance director, the cost of service of the subpoena shall be borne in the same manner as other expenses under the provisions of this article. When a witness is subpoenaed at the instance of any party to any such proceeding, the finance director may require that the cost of service of the subpoena be borne by the party at whose instance the witness is summoned. The finance director, in his or her discretion, may require a deposit to cover the cost of such service. A subpoena issued as aforesaid shall be served in the same manner as a subpoena issued out of the municipal court. (Code 1979, § 36-206)