A user shall have an affirmative defense to an enforcement action brought against it for noncompliance with the general prohibitions in §
187-5A of this Part
1 or the specific prohibitions in §
187-5B of this Part
1 if it can prove that it did not know, or have reason to know, that its discharge, alone or in conjunction with discharges from other sources, would cause pass-through or interference and that either:
A. A local limit exists for each pollutant discharged and the user was
in compliance with each limit directly prior to, and during, the pass-through
or interference; or
B. No local limit exists, but the discharge did not change substantially
in nature or constituents from the user's prior discharge when the
POTW-TP was regularly in compliance with its NPDES permit and, in
the case of interference, was in compliance with applicable sludge
use or disposal requirements.