620 ILCS 25/33
In any case in which: (1) it is desired to remove, lower, or otherwise terminate a non-conforming structure or use; or (2) the approach protection necessary cannot, because of constitutional limitations, be provided by airport zoning regulations under this Act; or (3) it appears advisable that the necessary approach protection be provided by acquisition of property rights rather than by airport zoning regulations, the Department, on behalf of and in the name of the State, within the limitation of available appropriations, or each political subdivision within which the property or non-conforming use is wholly or partly located or the political subdivision owning, operating, controlling or which is lessee or lessor of the airport or is served by it may acquire, by purchase, grant, or condemnation in the manner provided by the law under which the Department, on behalf of and in the name of the State, or political subdivisions are authorized to acquire real property for public purposes, such air right, avigation easement, or other estate or interest in the property or non-conforming structure or use in question as may be necessary to effectuate the purposes of this Act.
620 ILCS 25/33