S.C. Code Ann. § 57-5-1630

No construction contract may be extended to include work not contemplated in the original award, except within the limitations imposed by the contract. Where in the judgment of the Secretary of the Department of Transportation it is in the public's interest and prices advantageous to the department are obtained, the department may extend contracts to include additional work. In every case, the commission must ratify the contract extension at the next succeeding commission meeting. Advertisement in the case of extensions of contracts under this section shall consist of detailed reports of the transactions made public at open meetings of the commission.