S.C. Code Ann. § 57-5-1390: Bond interest, maturity, and redemption.

Turnpike bonds shall bear interest, payable on occasions prescribed by the State Fiscal Accountability Authority, at a rate not exceeding the maximum prescribed by Section 11-9-350. Each issue of turnpike bonds shall mature on the occasion prescribed by the State Fiscal Accountability Authority, not exceeding forty years from the date the bonds bear. Turnpike bonds may, in the discretion of the State Fiscal Accountability Authority, be made subject to redemption at par and accrued interest, plus such redemption premium as it approves and on occasions and under conditions it prescribes. Turnpike bonds are not redeemable before maturity unless they contain a statement to that effect.