d) If the results of testing of leachate samples in accordance with subsection (b) of this Section confirm that the leachate exceeds the limits for potentially usable waste as defined in Section 817.106, the operator shall:

1. 1) notify the Agency in writing of this finding within 10 days following the finding;
2. 2) verify the exceedence by taking additional samples within 45 days after the initial observation;
3. 3) report the results of the verification sampling to the Agency within 60 days after the initial observation;
4. 4) determine the cause of the exceedence which may include, but not be limited to, the waste itself, natural phenomena, sampling or analysis errors, or an offsite source;
5. 5) notify the Agency in writing of a confirmed exceedence and provide the rationale used in such a determination within ten days after the determination; and
6. 6) if the exceedence is attributable to the landfill, return to a quarterly sampling program for organics until such time as the exceedences cease.

e) If, as a result of further testing of the leachate pursuant to subsection (d)(2) of this Section and statistical analysis of the results in accordance with 35 Ill. Adm. Code 811.320(e), it is determined that the facility leachate exceeds the Section 817.106 limits for potentially usable waste, but does not exceed the limits for low risk waste, the facility shall:

1. 1) no longer be subject to the potentially usable waste landfill requirements of Subpart C of this Part;
2. 2) immediately be subject to the requirements for Low Risk Waste Landfills of 35 Ill. Adm. Code 814.602.

f) If the results of the retesting completed pursuant to Section 817.305(d)(2) indicate that the leachate exceeds the Section 817.106 limits for low risk waste landfills, the facility shall:

1. 1) no longer be subject to the potentially usable waste landfill requirements of Subpart C of this Part;
2. 2) immediately cease accepting waste;
3. 3) within 60 days, develop a closure plan that incorporates the requirements of 35 Ill. Adm. Code 811.Subpart C; and
4. 4) initiate closure within 90 days pursuant to a closure plan and complete closure within one year or pursuant to an alternate closure schedule that has been approved, in writing, by the Agency.