Indiana Administrative Code › Title 327 - WATER POLLUTION CONTROL DIVISION › Article 5 - INDUSTRIAL WASTEWATER PRETREATMENT PROGRAMS AND NPDES › Rule 10 - Additional Treatment Requirements › Section 10-5 - Small sanitary discharge

Current through July 10, 2024
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
Affected: IC 13-11-2; IC 13-18-4
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 (May-November)
Winter (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.