S.C. Code Ann. § 9-1-250

At least once in each five-year period, the first of which began in 1947, the actuary shall make an actuarial investigation into the mortality, service and compensation experience of the members and beneficiaries of the System and shall make a valuation of the contingent assets and liabilities of the System and the Board, after taking into account the results of such investigations and valuations, shall adopt for the System such mortality, service and other tables as shall be deemed necessary.