(415 ILCS 5/55.5) (from Ch. 111 1/2, par. 1055.5)
    Sec. 55.5. (a) The Agency shall investigate alleged violations of this Title XIV, or of any regulation promulgated hereunder, or of any approval granted by the Agency, and may cause such other investigations to be made as it may deem advisable.
    (b) If an investigation discloses that a violation may exist, the Agency shall take action pursuant to Title VIII of this Act in a timely manner.
    (c) Notwithstanding the provisions of subsection (b) of this Section, prior to taking action pursuant to Title VIII for violation of subsection (a), (b) or (c) of Section 55 of this Act, the Agency or unit of local government shall issue and serve upon the person complained against a written warning notice informing such person that the Agency or unit of local government intends to take such action. Such written warning notice shall specify the alleged violation, describe the corrective action which should be taken, and provide a period of 30 days in which one of the following response actions may be taken by such person:
        (1) initiation and completion of the corrective
    
action, and notification of the Agency or unit of local government in writing that such action has been taken; or
        (2) notification of the Agency or unit of local
    
government in writing that corrective action will be taken and completed within a period of 45 days from the date of issuance of the warning notice.
    In the event that the person fails to take a response action, initiates but does not adequately complete a response action, or takes other action in contravention of the described corrective action, the Agency or unit of local government may proceed pursuant to subsection (b) of this Section. If the same person has been issued 2 written warning notices for similar violations in any calendar year, thereafter the Agency or unit of local government may proceed pursuant to subsection (b) without first following the provisions of this subsection for the remainder of such calendar year with respect to such person.
(Source: P.A. 91-357, eff. 7-29-99.)