220 ILCS 75/35
For the purpose of making land surveys and land use studies, any applicant that has been granted a certificate of authority under this Section may, 30 days after providing written notice to the landowner thereof by registered mail and after providing a second notice to the owner of record, as identified in the records of the relevant county tax assessor, by telephone or email or by registered mail if the landowner has not been notified by other means, at least 3 days, but not more than 15 days, prior to the stated date in the notice, identifying the date when land surveys and land use studies will first begin on the landowner's property and informing the landowner that the landowner or the landowner's agent may be present when the land surveys or land use studies occur, enter upon the property of any landowner who has refused permission for entrance upon that property, but subject to responsibility for all damages which may be inflicted thereby.
220 ILCS 75/35