Section 2.23 - Affirmative Defenses(1) It shall be an affirmative defense to any enforcement action that the noncompliance was caused by an Upset as defined in 360 CMR 10.004: General Requirements. In such action, the Person seeking to establish the occurrence of an Upset shall have the burden of proof, which will be met if the Person:(a) Has reported the following information to the Authority within 24 hours of becoming aware of the Upset (if the information is provided orally, a written submission must be provided within five days):1. A description of the discharge and cause of noncompliance;2. The period of noncompliance, including exact dates and times or, if not corrected, the anticipated time the noncompliance is expected to continue; and3. Steps being taken and/or planned to reduce, eliminate, and prevent recurrence of the noncompliance; and(b) Demonstrates through properly signed contemporaneous operating logs or other relevant evidence that: 1. An Upset occurred and that the Person can identify the cause(s) of the Upset; and2. The facility was at the time being operated in a prudent and skillful manner and in compliance with applicable operation and maintenance procedures and with the requirements of 360 CMR 10.013(5)(a).(2) It shall be an affirmative defense to any enforcement action brought for noncompliance with 360 CMR 10.021: General Prohibitions that:(a) the Person did not know or have reason to know that its discharge, alone or in conjunction with a discharge or discharges from other sources, would violate 360 CMR 10.021: General Prohibitions; and(b) the Person's discharge complied with 360 CMR 10.023: Specific Prohibitions and 360 CMR 10.024: Specific Discharge Limitations/Local Limits, the specific discharge limitations and prohibitions in any permit issued to it by the Authority, and any applicable National Categorical Pretreatment Standard.Amended by Mass Register Issue 1399, eff. 9/6/2019.