In order to finance the continuing liability established with other agencies of state government, the Workers' Compensation Trust Fund is authorized to retain all moneys paid into the fund as premiums on policies of insurance and all moneys received as interest and all moneys received from other sources as a reserve for the payment of such liability and the expenses necessary to the proper conduct of such insurance program administered by the fund. Any amounts held by the Workers' Compensation Trust Fund which are available for investment shall be paid over to the Office of Treasury and Fiscal Services. The director of the Office of Treasury and Fiscal Services shall deposit such funds in a trust account for credit only to the Workers' Compensation Trust Fund. The director of the Office of Treasury and Fiscal Services shall invest such funds subject to the limitations of Code Section 50-5A-7 and Chapter 17 of this title. All income derived from such investments shall accrue to the Workers' Compensation Trust Fund. When moneys are paid over to the Office of Treasury and Fiscal Services, as provided in this Code section, the commissioner shall submit an estimate of the date such funds shall no longer be available for investment. When the commissioner wishes to withdraw funds from the trust account provided for in this Code section, he or she shall submit a request for such withdrawal, in writing, to the director of the Office of Treasury and Fiscal Services.