S.C. Code § 6-21-500
If any surplus shall be accumulated in the contingent fund over and above that which the governing body shall find may be necessary for reasonable and proper improvements, betterments and extensions to the existing system, project or combined system during the current calendar, operating or fiscal year and the next ensuing calendar, operating or fiscal year, any such excess may be transferred to the bond and interest redemption fund or may be applied, in so far as possible, in the purchase or retirement of outstanding bonds issued under the provisions of this chapter and for that purpose the governing body may purchase bonds not due in the open market at not more than the fair market value thereof. When such bonds are purchased for investment the income from such investment shall be carried into the contingent fund.
S.C. Code § 6-21-500