The corporate authorities of any forest preserve district, without submitting the question to the electors thereof for approval, may authorize by ordinance the issuance of refunding bonds (1) to refund its bonds prior to their maturity; (2) to refund its unpaid matured bonds; (3) to refund matured coupons evidencing interest upon its unpaid bonds; (4) to refund interest at the coupon rate upon its unpaid matured bonds that has accrued since the maturity of those bonds; and (5) to refund its bonds which by their terms are subject to redemption before maturity.
     The refunding bonds may be made registerable as to principal and may bear interest at a rate not to exceed six per cent annually, payable at such time and place as may be provided in the bond ordinance.
     The refunding bonds shall remain valid even though one or more of the officers executing the bonds ceases to hold his or their offices before the bonds are delivered.