SDCL § 6-8B-32: Voluntary surrender required to refund bonds not maturing or callable for twenty-five years--Provision for payment.

No bonds may be refunded unless the holders thereof voluntarily surrender them for exchange or payment, or unless they either mature or are callable for prior redemption under their terms within twenty-five years from the date of issuance of the refunding bonds. Provision shall be made for paying the bonds being refunded within the period of time.