There is hereby created in the State Treasury a revolving fund for the Department of Mental Health and Substance Abuse Services to be designated the “Intra-agency Reimbursement Revolving Fund”. The fund shall be a continuing fund not subject to fiscal year limitations. Revenues to the fund shall consist only of intra-agency payments from the allocation of operating costs among budgeted activities. All monies accruing to the credit of said fund are hereby appropriated and may be budgeted and expended by the Department of Mental Health and Substance Abuse Services for operating expenses of the Department of Mental Health and Substance Abuse Services. Expenditures from said fund shall be made upon warrants issued by the State Treasurer against claims filed as prescribed by law with the Director of the Office of Management and Enterprise Services for approval and payment.