Any amounts held by the health insurance 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 health insurance fund. The director of the Office of Treasury and Fiscal Services shall invest these health insurance funds subject to the limitations of Code Section 50-5A-7 and Chapter 17 of Title 50. All income derived from such investments shall accrue to the health insurance 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.