Virginia Administrative Code
Title 9 - ENVIRONMENT
Agency 25 - STATE WATER CONTROL BOARD
Chapter 31 - VIRGINIA POLLUTANT DISCHARGE ELIMINATION SYSTEM (VPDES) PERMIT REGULATION
Part III - Permit Conditions
Section 9VAC25-31-230 - Calculating VPDES permit conditions
Universal Citation: 9 VA Admin Code 25-31-230
Current through Register Vol. 41, No. 3, September 23, 2024
A. Permit effluent limitations, monitoring requirements, standards and prohibitions shall be established for each outfall or discharge point of the permitted facility, except as otherwise provided under 9VAC25-31-220 and subsection H of this section (limitations on internal waste streams).
B. Production-based limitations.
1. In the case of POTWs, permit
effluent limitations, standards, or prohibitions shall be calculated based on
design flow.
2.
a. Except in the case of POTWs or as provided
in subdivision 2 b of this subsection, calculation of any permit limitations,
standards, or prohibitions which are based on production (or other measure of
operation) shall be based not upon the designed production capacity but rather
upon a reasonable measure of actual production of the facility. For new sources
or new dischargers, actual production shall be estimated using projected
production. The time period of the measure of production shall correspond to
the time period of the calculated permit limitations; for example, monthly
production shall be used to calculate average monthly discharge limitations.
b.
(1)
(a) The
department may include a condition establishing alternate permit limitations,
standards, or prohibitions based upon anticipated increased (not to exceed
maximum production capability) or decreased production levels.
(b) For the automotive manufacturing industry
only, the department may establish a condition under subdivision 2 b (1) (a) of
this subsection if the applicant satisfactorily demonstrates to the department
at the time the application is submitted that its actual production, as
indicated in subdivision 2 a of this subsection, is substantially below maximum
production capability and that there is a reasonable potential for an increase
above actual production during the duration of the permit.
(2) If the department establishes permit
conditions under subdivision 2 b (1) of this subsection:
(a) The permit shall require the permittee to
notify the department at least two business days prior to a month in which the
permittee expects to operate at a level higher than the lowest production level
identified in the permit. The notice shall specify the anticipated level and
the period during which the permittee expects to operate at the alternate
level. If the notice covers more than one month, the notice shall specify the
reasons for the anticipated production level increase. New notice of discharge
at alternate levels is required to cover a period or production level not
covered by prior notice or, if during two consecutive months otherwise covered
by a notice, the production level at the permitted facility does not in fact
meet the higher level designated in the notice;
(b) The permittee shall comply with the
limitations, standards, or prohibitions that correspond to the lowest level of
production specified in the permit, unless the permittee has notified the
department under subdivision 2 b (2) (a) of this subsection, in which case the
permittee shall comply with the lower of the actual level of production during
each month or the level specified in the notice; and
(c) The permittee shall submit with the DMR
the level of production that actually occurred during each month and the
limitations, standards, or prohibitions applicable to that level of
production.
C. All permit effluent limitations, standards, or prohibitions for a metal shall be expressed in terms of total recoverable metal as defined in 40 CFR Part 136 unless:
1. An applicable effluent standard or
limitation has been promulgated under the CWA and specifies the limitation for
the metal in the dissolved or valent or total form; or
2. In establishing permit limitations on a
case-by-case basis under
40 CFR
125.3, it is necessary to express the
limitation on the metal in the dissolved or valent or total form to carry out
the provisions of the CWA and the law; or
3. All approved analytical methods for the
metal inherently measure only its dissolved form (e.g., hexavalent
chromium).
D. For continuous discharges all permit effluent limitations, standards, and prohibitions, including those necessary to achieve water quality standards, shall unless impracticable be stated as:
1.
Maximum daily and average monthly discharge limitations for all dischargers
other than publicly owned treatment works; and
2. Average weekly and average monthly
discharge limitations for POTWs.
E. Discharges which are not continuous, as defined in 9VAC25-31-10, shall be particularly described and limited, considering the following factors, as appropriate:
1. Frequency;
2. Total mass;
3. Maximum rate of discharge of pollutants
during the discharge; and
4.
Prohibition or limitation of specified pollutants by mass, concentration, or
other appropriate measure.
F. Mass Limitations.
1. All pollutants limited in permits shall
have limitations, standards or prohibitions expressed in terms of mass except:
a. For pH, temperature, radiation, or other
pollutants which cannot appropriately be expressed by mass;
b. When applicable standards and limitations
are expressed in terms of other units of measurement; or
c. If in establishing technology-based permit
limitations on a case-by-case basis, limitations expressed in terms of mass are
infeasible because the mass of the pollutant discharged cannot be related to a
measure of operation (for example, discharges of TSS from certain mining
operations), and permit conditions ensure that dilution will not be used as a
substitute for treatment.
2. Pollutants limited in terms of mass
additionally may be limited in terms of other units of measurement, and the
permit shall require the permittee to comply with both limitations.
G. Pollutants in intake water.
1. Upon request of the discharger,
technology-based effluent limitations or standards shall be adjusted to reflect
credit for pollutants in the discharger's intake water to the extent necessary
to meet the applicable technology-based limitation or standard, up to a maximum
value equal to the influent value. Credit shall be granted only if:
a. The applicable effluent limitations and
standards contained in the regulations incorporated by reference in
9VAC25-31-30
specifically provide that they shall be applied on a net basis; or
b. The discharger demonstrates that the
control system it proposes or uses to meet applicable technology-based
limitations and standards would, if properly installed and operated, meets the
limitations and standards in the absence of pollutants in the intake
waters.
2. Credit for
generic pollutants such as biochemical oxygen demand (BOD) or total suspended
solids (TSS) should not be granted unless the permittee demonstrates that the
constituents of the generic measure in the effluent are substantially similar
to the constituents of the generic measure in the intake water or unless
appropriate additional limits are placed on process water pollutants either at
the outfall or elsewhere.
3. Credit
for the level of pollutants in the intake water may be considered in setting
water quality-based effluent limitations according to
9VAC25-31-220
D. Where a total maximum daily load has been established for the receiving
waterbody and it is applicable to the discharge, it shall be considered when
such effluent limitations are developed. The department may consider the
presence of intake pollutants when determining either that water quality-based
effluent limitations are not necessary under
9VAC25-31-220
D or that any water quality-based effluent limitations justified by
9VAC25-31-220
D will be established in a manner that does not hold the permittee responsible
for removing pollutants originating in its intake water.
4. Additional monitoring may be necessary to
determine eligibility for any credits and compliance with permit
limits.
5. Credits shall be granted
only if the discharger demonstrates that the intake water is drawn from the
same body of water into which the discharge is made. The department may waive
this requirement for technology-based effluent limitations, standards, and
prohibitions if he finds that no environmental degradation will result.
a. An intake pollutant is considered to be
from the same body of water as the discharge if the department finds that the
intake pollutant would have reached the vicinity of the outfall point in the
receiving water within a reasonable period had it not been removed by the
permittee. This finding may be deemed established if:
(1) The background concentration of the
pollutant in the receiving water (excluding any amount of the pollutant in the
facility's discharge) is similar to that in the intake water;
(2) There is direct hydrological connection
between the intake and discharge points; and
(3) Water quality characteristics (e.g.,
temperature, pH, hardness) are similar in the intake and receiving waters.
Other site-specific factors relevant to the transport and fate of the pollutant may be considered in making this finding.
b. An intake pollutant
from groundwater may be considered to be from the same body of water if the
department determines that the pollutant would have reached the vicinity of the
outfall point in the receiving water within a reasonable period had it not been
removed by the permittee, except that such a pollutant is not from the same
body of water if the groundwater contains the pollutant partially or entirely
due to human activity, such as industrial, commercial, or municipal operations,
disposal actions or treatment processes.
c. For pollutants in intake water provided by
a water supply system, where the raw water supply is removed from the same body
of water as the discharge, the concentration of the intake pollutant shall be
determined at the point where the water enters the water supplier's
distribution system.
d. Where a
facility discharges intake pollutants that originate in part from the same body
of water and in part from a different body of water, the effluent limitation
may provide for intake credits for the portion of the pollutants derived from
the same body of water, provided that adequate monitoring to determine
compliance can be established and is included in the permit.
6. Credits shall not be granted if
the discharger contributes to the level of the pollutant in the intake water
prior to the intake.
7. Credits for
intake pollutants do not apply to technology-based limitations on the discharge
of raw water clarifier sludge generated from the treatment of intake
water.
H. Internal waste streams.
1. When permit effluent limitations
or standards imposed at the point of discharge are impractical or infeasible,
effluent limitations or standards for discharges of pollutants may be imposed
on internal waste streams before mixing with other waste streams or cooling
water streams. In those instances, the monitoring required by
9VAC25-31-220
I shall also be applied to the internal waste streams.
2. Limits on internal waste streams will be
imposed only when the fact sheet sets forth the exceptional circumstances which
make such limitations necessary, such as when the final discharge point is
inaccessible, the wastes at the point of discharge are so diluted as to make
monitoring impracticable, or the interferences among pollutants at the point of
discharge would make detection or analysis impracticable.
I. Disposal of pollutants into wells, POTWs or by land application.
1. When part of a
discharger's process wastewater is not being discharged into surface waters or
into the contiguous zone because it is disposed into a well, into a POTW, or by
land application thereby reducing the flow or level of pollutants being
discharged into surface waters, applicable effluent standards and limitations
for the discharge in a VPDES permit shall be adjusted to reflect the reduced
raw waste resulting from such disposal. Effluent limitations and standards in
the permit shall be calculated by one of the following methods:
a. If none of the waste from a particular
process is discharged into surface waters, and effluent limitations guidelines
provide separate allocation for wastes from that process, all allocations for
the process shall be eliminated from calculation of permit effluent limitations
or standards.
b. In all cases other
than those described in subdivision 1 a of this subsection, effluent
limitations shall be adjusted by multiplying the effluent limitation derived by
applying effluent limitation guidelines to the total waste stream by the amount
of wastewater flow to be treated and discharged into surface waters, and
dividing the result by the total wastewater flow. Effluent limitations and
standards so calculated may be further adjusted to make them more or less
stringent if discharges to wells, publicly owned treatment works, or by land
application change the character or treatability of the pollutants being
discharged to receiving waters. This method may be algebraically expressed as:
|
P = |
E x N |
|
T |
where P is the permit effluent limitation, E is the limitation derived by applying effluent guidelines to the total wastestream, N is the wastewater flow to be treated and discharged to surface waters, and T is the total wastewater flow.
2. Subdivision 1 of this subsection does not
apply to the extent that promulgated effluent limitations guidelines:
a. Control concentrations of pollutants
discharged but not mass; or
b.
Specify a different specific technique for adjusting effluent limitations to
account for well injection, land application, or disposal into POTWs.
3. Subdivision 1 of this
subsection does not alter a discharger's obligation to meet any more stringent
requirements established in the permit.
Statutory Authority: § 62.1-44.15 of the Code of Virginia; § 402 of the federal Clean Water Act; 40 CFR Parts 122, 123, 124, 403, and 503.
Disclaimer: These regulations may not be the most recent version. Virginia may have more current or accurate information. We make no warranties or guarantees about the accuracy, completeness, or adequacy of the information contained on this site or the information linked to on the state site. Please check official sources.
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