210 ILCS 95/13

Whenever the Department determines that there are reasonable grounds to believe that there has been a violation of any provision of this Act or the rules and regulations issued hereunder, the Department shall give notice of such alleged violation to the owner, operator, licensee or permit holder as herein provided. Such notice shall: (a) be in writing; (b) include a statement of the reasons for the issuance of the notice; (c) allow reasonable time as determined by the Department for the performance of any act it requires; (d) be served upon the owner, licensee or permit holder as the case may require; provided, that such notice or order shall be deemed to have been properly served upon such owner, licensee or permit holder when a copy thereof has been sent by registered or certified mail to his last known address as furnished to the Department; or, when he has been served with such notice by any other method authorized by the Laws of this State; (e) contain an outline of remedial action, which, if taken, will be required to effect compliance with the provisions of this Act and the rules and regulations issued hereunder. (Source: P.A. 84-650.)