35 Ill. Adm. Code 310.921
Substantial Modifications Defined
Section 310
Section 310.921Â Substantial
Modifications Defined
Substantial modifications
include the following types of modifications:
a)Â Â Â Â Â Â Â Â Modifications that relax POTW legal authorities (as described
in Section 310.510(a)), except for modifications that directly reflect a
revision to this Part or to 35 Ill. Adm. Code:Â Subtitle C, and are reported
pursuant to Section 310.923;
b)Â Â Â Â Â Â Â Â Modifications that relax local limits, except for the
modifications to local limits for pH and reallocations of the maximum allowable
industrial loading of a pollutant that do not increase the total industrial
loadings for the pollutant, which are reported pursuant to Section 310.923.Â
For this Section, "maximum allowable industrial loading" means the
total mass of a pollutant that all industrial users of a POTW (or a subgroup of
industrial users identified by the POTW) may discharge pursuant to limits developed
under Section 310.210;
c)Â Â Â Â Â Â Â Â Changes to the POTW's control mechanism, as the control
mechanism is described in Section 310.510(a)(3);
d)Â Â Â Â Â Â Â Â A decrease in the frequency of self-monitoring or reporting
required of industrial users;
e)Â Â Â Â Â Â Â Â A decrease in the frequency of industrial user inspections or
sampling by the POTW;
f)Â Â Â Â Â Â Â Â Changes to the POTW's confidentiality procedures; and
g)Â Â Â Â Â Â Â Â Other modifications designated as substantial modifications by
the Agency on any of the following bases:
1)Â Â Â Â Â Â Â Â The modification could have a significant impact on the
operation of the POTW's pretreatment program;
2)Â Â Â Â Â Â Â Â The modification could result in an increase in pollutant
loadings at the POTW; or
3)Â Â Â Â Â Â Â Â The modification could result in less stringent requirements
being imposed on industrial users of the POTW.
BOARD NOTE:
Derived from 40 CFR 403.18(b) (1997), as amended at 62 Fed. Reg. 38414 (July
17, 1997).