Current through Register Vol. 49, No. 13, September 23, 2024
Subpart
1.
General.
A. The
combined waste stream formula described in this part is used to derive fixed
alternative discharge limits to be applied to the mixed effluent when waste
streams subject to national categorical pretreatment standards are mixed with
waste streams subject to other categorical standards or waste streams not
subject to categorical standards. Alternative discharge limits may be derived
using the combined waste stream formula by the control authority or by the
industrial user with the prior written concurrence of the control authority.
Alternative limits must be derived for all applicable limits. When deriving
alternative categorical limits, the control authority or industrial user shall
calculate both an alternative daily maximum value using the daily maximum
values specified in the appropriate categorical pretreatment standards and an
alternative consecutive sampling day average value using the monthly average
values specified in the appropriate categorical pretreatment standards. The
industrial user shall comply with the alternative daily maximum and long-term
average limits fixed by the control authority until the control authority
modifies the limits or approves an industrial user modification request.
Modification is authorized whenever there is a material or significant change
in the values used in the calculation to fix alternative limits for the
regulated pollutant. An industrial user shall immediately report any material
or significant change to the control authority. If appropriate, new alternative
categorical limits shall be calculated within 30 days. The industrial user may
change monitoring points only after receiving prior written approval from the
control authority. The control authority shall ensure that any change in an
industrial user's monitoring points will not allow the industrial user to
substitute dilution for adequate treatment to achieve compliance with
applicable standards.
B. If process
effluent is mixed prior to treatment with wastewaters other than those
generated by the regulated process, fixed alternative discharge limits shall be
derived by the control authority or by the industrial user with the prior
written concurrence of the control authority.
C. If a treated regulated process waste
stream is combined prior to treatment with wastewaters other than those
generated by the regulated process, the industrial user may, with the approval
of the control authority, monitor either the segregated process waste stream or
the combined waste stream to determine compliance with applicable pretreatment
standards. If the industrial user chooses to monitor the segregated process
waste stream, the industrial user shall apply the applicable categorical
pretreatment standard. If the industrial user chooses to monitor the combined
waste stream, the industrial user shall apply an alternative discharge limit
calculated using the combined waste stream formula as provided in this part.
The industrial user may change monitoring points only after receiving prior
written approval from the control authority. The control authority shall ensure
that any change in an industrial user's monitoring points will not allow the
industrial user to substitute dilution for adequate treatment to achieve
compliance with applicable standards.
D. If a regulated process waste stream is
combined without treatment with wastewaters other than those generated by the
regulated process, the industrial user may, with the approval of the control
authority, monitor either the segregated process waste stream or the combined
waste stream to determine compliance with applicable pretreatment standards. If
the industrial user chooses to monitor the segregated process waste stream, the
industrial user shall apply the applicable categorical pretreatment standard.
If the industrial user chooses to monitor the combined waste stream, the
industrial user shall apply an alternative discharge limit calculated using the
combined waste stream formula as provided in this part. However, when no
treatment is provided, all waste streams other than the regulated process waste
stream are considered to be dilute waste streams in deriving alternative
discharge limits. If more than one regulated process waste stream is present at
the chosen monitoring point, the combined waste stream formula shall be applied
to each regulated process waste stream separately, with all other waste streams
considered to be dilute waste streams, and the most restrictive limit applied,
for each pollutant. The industrial user may change monitoring points only after
receiving approval from the control authority. The control authority shall
ensure that any change in an industrial user's monitoring points will not allow
the industrial user to substitute dilution for adequate treatment to achieve
compliance with applicable standards.
Subp. 2.
Alternative limit calculation;
definitions.
For purposes of the formulas in subpart
3, the following symbols have
the meanings specified.
Ct = the alternative concentration limit
for the combined waste stream.
Mt = the alternative mass limit for a
pollutant in the combined waste stream.
Ci = the categorical pretreatment
standard concentration limit for a pollutant in the regulated stream i.
Mi = the categorical pretreatment
standard mass limit for a pollutant in the regulated stream i (the categorical
pretreatment mass limit multiplied by the appropriate measure of
production).
Fi = the average daily flow (at least a
30-day average) of stream i to the extent that it is regulated for the
pollutant.
FD = the average daily flow (at least a
30-day average) of dilute waste streams.
If waste streams contain a significant amount of a pollutant
and the combination of the streams, prior to treatment, with an industrial
user's regulated process waste streams will result in a substantial reduction
of that pollutant, the control authority shall determine whether the streams
should be classified as dilute or unregulated. Dilute waste streams include,
but are not limited to:
A. boiler
blowdown streams, noncontact cooling streams, storm water streams, and
demineralizer backwash streams;
B.
sanitary waste streams when the streams are not regulated by a categorical
pretreatment standard; and
C.
process waste streams from processes that were or could have been entirely
exempted from categorical pretreatment standards because:
(1) the regulated pollutants are not
detectable in the effluent from the industrial user;
(2) the regulated pollutants are present only
in trace amounts and are neither causing nor likely to cause toxic
effects;
(3) the regulated
pollutants are present in amounts too small to be effectively reduced;
or
(4) the waste stream contains
only pollutants that are compatible with the receiving POTW.
FT = the total average daily flow
through the combined treatment facility (this includes all
Fi, FD, and unregulated
streams).
N = the total number of regulated streams.
For purposes of this subpart, "average daily flow" means a
reasonable measure of the average daily flow for at least a 30-day period. For
new sources, flows shall be estimated using projected values.
Subp. 3.
Alternative limit calculation; formula.
The alternative limit for a specified pollutant is derived by
the use of either of the following formulas:
A. alternative concentration limit under Code
of Federal Regulations, title 40, section 403.6(e)(1)(i); or
B. alternative mass limit under Code of
Federal Regulations, title 40, section 403.6(e)(1)(ii).
Subp. 4.
Alternate limits below
detection limit.
An alternative pretreatment limit derived by the combined waste
stream formula may not be used if the alternative limit is below the analytical
detection limit for any of the regulated pollutants.
Statutory Authority: MS s
115.03
