this rule and the specific prohibitions in subrule (2)(c), (d), (e), and (f) of this rule if the
user can demonstrate both of the following:
(a) It did not know or have reason to know that its discharge, alone or in
conjunction with a discharge or discharges from other sources, would cause pass-
through or interference.
(b) A local limit designed to prevent pass-through or interference was developed in
accordance with subrule (4) of this rule for each pollutant in the user's discharge that
caused pass-through or interference, and the user was in compliance with each local limit
directly before and during the pass-through or interference, or if a local limit designed
to prevent pass-through or interference has not been developed in accordance with
subrule (4) of this rule for the pollutant that caused the pass-through or interference, the
user's discharge directly before and during the pass-through or interference did not
change substantially in nature or constituents from the user's prior discharge activity
when the publicly owned treatment works was regularly in compliance with its
national pollutant discharge elimination system permit requirements and, in the case of
interference, applicable requirements for sewage sludge use or disposal.
(4) All of the following provisions apply to local limits:
(a) Publicly owned treatment works required by permit to develop a pretreatment
program shall develop and enforce local limits to implement the prohibitions listed in
subrules (1) and (2) of this rule. Each publicly owned treatment works that has an
approved pretreatment program shall review and update the local limits, as follows:
(i) When new pollutants are introduced.
(ii) When new pollutants that are previously unevaluated are identified.
(iii) When substantial increases of pollutants are proposed as required in the
notification of new or increased uses in accordance with the provisions of 40 C.F.R.
(iv) As required in a national pollutant discharge elimination system permit
application in accordance with the provisions of 40 C.F.R. §122.21(j)(4) (1990).
(b) In addition to the requirements of subdivision (a) of this subrule, each publicly
owned treatment works shall evaluate the need for local limits for all pollutants of
concern. At a minimum, the publicly owned treatment works shall evaluate the
following parameters for local limits: arsenic, cadmium, chromium, copper, cyanide,
lead, mercury, nickel, silver, and zinc. Sufficient representative data shall be obtained
for determining the limits by performing any of the following monitoring plans:
(i) One sample each per month for a year of wastewater treatment plant influent,
effluent, sludge, discharges at other locations, as appropriate, and sanitary sewage, with
not less than 2 separate sampling events each weekday, Monday to Friday.
(ii) Six samples each taken over a 4-week period of wastewater treatment plant
influent, effluent, sludge, discharges at other locations, as appropriate, and sanitary
sewage, with at least 1 sampling event each weekday, Monday to Friday.
(iii) An alternative plan, which may include historical data, which is approved by
the approval authority.
(c) Local limits shall not be adopted without public notice and an opportunity to
(d) Where local limits are developed by a publicly owned treatment works in
accordance with this subrule, the limits shall be deemed pretreatment standards.