Any bonds of the authority at any time outstanding may at any time and from time to time be refunded by the authority by the issuance of its refunding bonds in such amount as the authority may deem necessary but not exceeding an amount sufficient to refund the principal of the bonds so to be refunded, together with any unpaid interest thereon and any premiums, commissions, service fees and other expenses necessary to be paid in connection therewith.
SDCL 1-16A-53