A county board may purchase or lease any real estate or personal property for public purposes under contracts providing for payment in installments over a period of time of not more than 20 years in the case of real estate, and not more than 10 years in the case of personal property, with interest on the unpaid balance owing not to exceed the maximum rate authorized by the Bond Authorization Act, as amended at the time of the making of the contract. The indebtedness incurred under this Section when aggregated with existing indebtedness may not exceed the debt limits provided in Section 5-1012.
     With respect to instruments for the payment of money issued under this Section or its predecessor either before, on, or after the effective date of Public Act 86-4, it is and always has been the intention of the General Assembly (i) that the Omnibus Bond Acts are and always have been supplementary grants of power to issue instruments in accordance with the Omnibus Bond Acts, regardless of any provision of this Act or “An Act to revise the law in relation to counties”, approved March 31, 1874, that may appear to be or to have been more restrictive than those Acts, (ii) that the provisions of this Section or its predecessor are not a limitation on the supplementary authority granted by the Omnibus Bond Acts, and (iii) that instruments issued under this Section or its predecessor within the supplementary authority granted by the Omnibus Bond Acts are not invalid because of any provision of this Act or “An Act to revise the law in relation to counties”, approved March 31, 1874, that may appear to be or to have been more restrictive than those Acts.