Authority: IC 13-13-5; IC 13-14-8; IC 13-14-9; IC 13-15-1-2;
IC 13-15-2-1; IC 13-18-3
Sec. 5.
(a) All
discharges from continuous discharge sanitary wastewater treatment facilities
with a design flow of five-hundredths (0.05) MGD or less (which are not
considered to be lake or sinkhole dischargers as defined under section 4 of
this rule) are subject to the following effluent limitations in the absence of
a site-specific water quality modeled waste load allocation:
(1) Effluent limitations for
CBOD5, TSS, and dissolved oxygen (DO):
|
Summer |
Winter |
|
Dilution Ratio (DR) |
CBOD5/TSS/DO |
CBOD5/TSS/DO |
|
DR less than or equal to 1 |
15 /18 / 6 |
25 /30 / 5 |
|
DR greater than 1, less than or equal to
3 |
20 /24 / - |
25 /30 / - |
|
DR greater than 3 |
25 /30 / - |
25 /30 / - |
(2)
Limitations for ammonia nitrogen shall be determined as follows:
(A) Effluent limitations for
NH3-N (ammonia nitrogen), calculated in accordance with
subdivision (5)(C):
|
Summer |
Winter |
|
(May-November) |
(December-April) |
|
Ammonia nitrogen |
Ammonia nitrogen |
|
1.06 + 0.43 DR |
1.58 + 0.69 DR |
(B)
When a properly designed and operated treatment facility qualifying for these
limitations, which is not hydraulically or organically overloaded is of the
type that is inherently capable of achieving the water quality standards for
ammonia nitrogen, and ammonia nitrogen will not be discharged at a level that
will cause, have the reasonable potential to cause, or contribute to an
excursion above a water quality criterion for ammonia under
327 IAC 2-1 or
327 IAC 2-1.5, the commissioner,
based on cost and other considerations, may exclude the ammonia nitrogen
effluent limitations or monitoring requirements from the permit. Such action is
not considered to be a variance from the applicable water quality
standards.
(C) When DR exceeds 16:1
for the summer period and 10:1 for the winter period, ammonia nitrogen
limitations will not be included in the permit, unless the commissioner can
demonstrate that ammonia will be discharged at a level that will cause, have
the reasonable potential to cause, or contribute to an excursion above a water
quality criterion for ammonia under
327 IAC 2-1 or
327 IAC 2-1.5.
(3) The alternative limitations
for total suspended solids applicable to waste stabilization lagoons as
described under
327 IAC 5-5-3(b)
may be applied to small sanitary discharges
from properly designed, operated, and loaded waste stabilization lagoon
treatment facilities in lieu of the limitations for TSS contained in
subdivision (1).
(4) If deemed
necessary to comply with water quality standards contained under
327 IAC 2-1 or
327 IAC 2-1.5, such as discharges
to streams which are classified for cold water aquatic life, more stringent
limitations for dissolved oxygen and ammonia nitrogen may be applied on a
case-by-case basis.
(5) The
following conditions apply within this subsection:
(A) All effluent limitations in subdivisions
(1) and (2) are expressed in milligrams per liter.
(B) CBOD5, TSS, and
ammonia nitrogen limitations are monthly average concentrations. Weekly average
limitations are one and five-tenths (1.5) multiplied by monthly average
limitations, except where CBOD5 equals twenty-five (25)
milligrams per liter, in which case the weekly average is forty (40) milligrams
per liter.
(C) Ammonia nitrogen
limitations are derived using conservation of mass principles, applying
one-half (½) stream flow (Q7,10) and using the
criteria contained in
327 IAC
2-1-6(b)(5)(A), using year-round
stream pH of seven and eight-tenths (7.8) s.u., instream temperature of
twenty-five degrees Celsius (25°C) summer, ten degrees Celsius (10°C)
winter, and two-tenths (0.2) milligrams per liter background ammonia nitrogen
year-round. If the discharge is in the Great Lakes system, ammonia nitrogen
limitations shall be derived using the criteria for ammonia nitrogen contained
in 327 IAC 2-1.5-8, the stream
design flow, mixing zone, and background determined in accordance with
327 IAC 5-2-11.4, and the
procedures to calculate WQBELs under
327 IAC 5-2-11.6.
(D) DR is calculated as
Q7,10 of receiving stream divided by the design flow of
the discharge.
(6) In
addition, water quality-based limitations for any other toxic substance may be
included in the permit if the toxic substance is or may be discharged at a
level that will cause, have the reasonable potential to cause, or contribute to
an excursion above any applicable narrative or numeric water quality criteria
or value promulgated under
327 IAC 2-1 or
327 IAC 2-1.5.
(b) Continuous discharges include
all discharges not designed, approved, and operated as controlled discharges
from multicelled waste stabilization ponds.
(c) Industrial plants with small sanitary
discharges mixing with other nontoxic, nonorganic, nonnutrient containing
wastewaters, such as cooling water, ash sluicing, etc. prior to discharge may
use the other wastewaters as dilution in applying the criteria of subsection
(a).
