420 ILCS 20/21.1

(a) For the purpose of conducting subsurface surveys and other studies under this Act, officers and employees of the Agency and officers and employees of any person under contract or subcontract with the Agency shall have the power to enter upon the lands or waters of any person upon written notice to the known owners and occupants, if any.

(b) In addition to the powers under subsection (a), and without limitation to those powers, the Agency and any person under contract or subcontract with the Agency shall also have the power to enter contracts and agreements which allow entry upon the lands or waters of any person for the purpose of conducting subsurface surveys and other studies under this Act.

(c) The Agency shall be responsible for any actual damages occasioned by the entry upon the lands or waters of any person under this Section.