Section 18.09 - Bond security and redemption fund(1) When bonds are authorized, there shall be established in the state treasury a bond security and redemption fund separate and distinct from every other fund, which shall contain separate and distinct sinking funds for each particular bond issue.(2) Each sinking fund shall be expended, and all moneys from time to time on hand therein are irrevocably appropriated, in sums sufficient, only for the payment of principal and interest on the bonds giving rise to it, premium, if any, due upon redemption of any such bonds, and payment due, if any, under an agreement or ancillary arrangement that has been entered into under s. 18.06(8) (a) with respect to any such bonds and that has been determined to be payable from the bond security and redemption fund under s. 18.06(8) (a) 2(3) One year after interest has ceased to accrue on all of the bonds giving rise to a sinking fund, all moneys on hand in such sinking fund shall be paid over and transferred to the state building trust fund and the sinking fund shall be closed. An amount equal to the aggregate face value of all outstanding bonds and the accrued interest thereon for which no sinking fund exists shall be maintained in the state building trust fund applicable exclusively to the payment of such bonds and interest.(4) Moneys of the bond security and redemption fund may be commingled only for the purpose of investment with other public funds, and they may be invested only as provided in s. 18.04(6) or 25.17(3) (dr) . All such investments shall be the exclusive property of such fund and all earnings on or income from such investments plus any transfers from the capital improvement fund under s. 18.08(3), (5) or (6) shall be distributed to the respective sinking funds by the department of administration for use in meeting periodic principal and interest payments on bonds issued.(5) There shall be transferred to each sinking fund a sum sufficient for the payment of the principal, interest and premium due, if any, on the bonds giving rise to it as the same falls due. Such transfers shall be so timed that there is at all times on hand in the sinking fund an amount not less than the aggregate amount of principal, interest and premium, if any, to be paid out of it during the ensuing 15 days. The amount of any transfer scheduled to be made to the sinking fund from an escrow account established under a refunding escrow agreement on or before the due date of any payment of principal, interest or premium shall be treated as an amount on hand in the sinking fund as of the 16th day before the due date or as of the 46th day before the due date if operating notes are outstanding. Notwithstanding the foregoing, no further such transfer need be made after there are on hand in the sinking fund from any source assets sufficient to pay the aggregate face value of all of the bonds giving rise to it outstanding, the amount of any premium payable on such payment and the amount of interest to accrue on such bonds until payment.1971 c. 125; 1983 a. 27 s. 2202 (5); 1985 a 6; 1987 a. 27; 2007 a. 20.