A. The Department of Environmental Quality,
after consultation with the Virginia Department of Wildlife Resources and the
U.S. Fish and Wildlife Service, has determined that the majority of Virginia
freshwaters are likely to contain, or have contained in the past, freshwater
mussel species in the family Unionidae and contain early life stages of fish
during most times of the year. Therefore, the ammonia criteria presented in
subsections B and C of this section are designed to provide protection to these
species and life stages. In an instance where it can be adequately demonstrated
that either freshwater mussels or early life stages of fish are not present in
a specific waterbody, potential options for alternate, site-specific criteria
are presented in subsection D of this section. Acute criteria are a one-hour
average concentration not to be exceeded more than once every three
years
1 on the average, and chronic criteria are
30-day average concentrations not to be exceeded more than once every three
years on the average.
2 In addition, the four-day
average concentration of total ammonia nitrogen (in mg N/L) shall not exceed
2.5 times the chronic criterion within a 30-day period more than once every
three years on the average.
1The default design flow for
calculating steady state wasteload allocations for the acute ammonia criterion
for freshwater is the 1Q10 (see
9VAC25-260-140
B footnote 6) unless statistically valid methods are employed that demonstrate
compliance with the duration and return frequency of the water quality
criteria.
2The default design flow for
calculating steady state wasteload allocations for the chronic ammonia
criterion for freshwater is the 30Q10 (see
9VAC25-260-140
B footnote 6) unless statistically valid methods are employed which demonstrate
compliance with the duration and return frequency of the water quality
criteria.
B. The acute
criteria for total ammonia (in mg N/L) for freshwaters with trout absent or
present are in the following tables:
View Image
View Image
The acute criteria for trout present shall apply to all
Class V-Stockable Trout Waters and Class VI-Natural Trout Waters as listed in
9VAC25-260-390
through
9VAC25-260-540.
The acute criteria for trout absent apply to all other fresh waters.
To calculate total ammonia nitrogen acute criteria values
in freshwater at different pH values than those listed in this subsection, use
the following equations and round the result to two significant digits:
Where trout are absent:
Acute Criterion Concentration (mg N/L) =
0.7249 X (
|
0.0114
|
+
|
1.6181
|
) X MIN
|
1 +
107.204-pH
|
1 +
10pH-7.204
|
Where MIN = 51.93 or 23.12 X 100.036 X (20 -
T), whichever is less
T = Temperature in
oC
Or where trout are present, whichever of the following
calculation results is less:
Acute Criterion Concentration (mg N/L) =
(
|
0.275
|
+
|
39.0
|
)
|
1 +
107.204-pH
|
1 +
10pH-7.204
|
or
0.7249 X (
|
0.0114
|
+
|
1.6181
|
) X (23.12 X 100.036X(20 °
T))
|
1 +
107.204-pH
|
1 +
10pH-7.204
|
T = Temperature in
oC
C. The chronic criteria for total ammonia
nitrogen (in mg N/L) where freshwater mussels and early life stages of fish are
present in freshwater are in the following table:
View Image
To calculate total ammonia nitrogen chronic criteria values
in freshwater when freshwater mussels and early life stages of fish are present
at different pH and temperature values than those listed in this subsection,
use the following equation and round the result to two significant
digits:
Chronic Criteria Concentration =
0.8876 X (
|
0.0278
|
+
|
1.1994
|
) X (2.126 X 100.028 X (20 -
MAX(T,7)))
|
1 + 107.688-pH
|
1 + 10pH-7.688
|
Where MAX = 7 or temperature in degrees Celsius, whichever
is greater
T = temperature in °C
D. Site-specific considerations and alternate
criteria. If it can be adequately demonstrated that freshwater mussels or early
life stages of fish are not present at a site, then alternate site-specific
criteria can be considered using the information provided in this subsection.
Recalculated site-specific criteria shall provide for the attainment and
maintenance of the water quality standards of downstream waters.
1. Site-specific modifications to the ambient
water quality criteria for ammonia to account for the absence of freshwater
mussels or early life stages of fish shall be conducted in accordance with the
procedures contained in this subdivision. Because the department presumes that
most state waterbodies have freshwater mussels and early life stages of fish
present during most times of the year, the criteria shall be calculated
assuming freshwater mussels and early life stages of fish are present using
subsections B and C of this section unless the following demonstration that
freshwater mussels or early life stages of fish are absent is successfully
completed. Determination of the absence of freshwater mussels requires special
field survey methods. This determination must be made after an adequate survey
of the waterbody is conducted by an individual certified by the Virginia
Department of Wildlife Resources for freshwater mussel identification and
surveys. Determination of absence of freshwater mussels will be done in
consultation with the Department of Wildlife Resources. Early life stages of
fish are defined in subdivision 2 of this subsection. Modifications to the
ambient water quality criteria for ammonia based on the presence or absence of
early life stages of fish shall only apply at temperatures below 15°C.
a. During the review of any new or existing
activity that has a potential to discharge ammonia in amounts that may cause or
contribute to a violation of the ammonia criteria contained in subsection B of
this section, the department may examine data from the following approved
sources in subdivisions 1 a (1) through (5) of this subsection or may require
the gathering of data in accordance with subdivisions 1 a (1) through (5) on
the presence or absence of early life stages of fish in the affected waterbody.
(1) Species and distribution data contained
in the Virginia Department of Wildlife Resources Wildlife Information System
database.
(2) Species and
distribution data contained in Freshwater Fishes of Virginia, 1994.
(3) Data and fish species distribution maps
contained in Handbook for Fishery Biology, Volume 3, 1997.
(4) Field data collected in accordance with
U.S. EPA's Rapid Bioassessment Protocols for Use in Streams and Wadeable
Rivers, Second Edition, EPA 841-B-99-002. Field data must comply with all
quality assurance and quality control criteria.
(5) The American Society for Testing and
Materials (ASTM) Standard E-1241-88, Standard Guide for Conducting Early
Life-Stage Toxicity Tests with Fishes.
b. If data or information from sources other
than subdivisions 1 a (1) through (5) of this subsection are considered, then
any resulting site-specific criteria modifications shall be reviewed and
adopted in accordance with the site-specific criteria provisions in
9VAC25-260-140
D and submitted to EPA for review and approval.
c. If the department determines that the data
and information obtained from subdivisions 1 a (1) through (5) of this
subsection demonstrate that there are periods of each year when no early life
stages are expected to be present for any species of fish that occur at the
site, the department shall issue a notice to the public and make available for
public comment the supporting data and analysis along with the department's
preliminary decision to authorize the site-specific modification to the ammonia
criteria. Such information shall include, at a minimum:
(1) Sources of data and
information.
(2) List of fish
species that occur at the site as defined in subdivision 3 of this
subsection.
(3) Definition of the
site. Definition of a "site" can vary in geographic size from a stream segment
to a watershed to an entire eco-region.
(4) Duration of early life stage for each
species in subdivision 1 c (2) of this subsection.
(5) Dates when early life stages of fish are
expected to be present for each species in subdivision 1 c (2) of this
subsection.
(6) Based on
subdivision 1 c (5) of this subsection, identify the dates (beginning date,
ending date), if any, where no early life stages are expected to be present for
any of the species identified in subdivision 1 c (2) of this
subsection.
d. If, after
reviewing the public comments received in subdivision 1 c of this subsection
and supporting data and information, the department determines that there are
times of the year when no early life stages are expected to be present for any
fish species that occur at the site, then the applicable ambient water quality
criteria for ammonia for those time periods shall be calculated using the table
in this subsection, or the formula for calculating the chronic criterion
concentration for ammonia when early life stages of fish are absent.
e. The department shall maintain a
comprehensive list of all sites where the department has determined that early
life stages of fish are absent. For each site the list will identify the
waterbodies affected and the corresponding times of the year that early life
stages of fish are absent. This list is available either upon request from the
Office of Water Quality Programs at 1111 East Main Street, Suite 1400 Richmond,
VA 23219, or from the department website at
http://www.deq.virginia.gov/programs/water/waterqualityinformationtmdls/waterqualitystandards.aspx.
2. The duration of the "early life
stages" extends from the beginning of spawning through the end of the early
life stages. The early life stages include the prehatch embryonic period, the
post-hatch free embryo or yolk-sac fry, and the larval period, during which the
organism feeds. Juvenile fish, which are anatomically similar to adults, are
not considered an early life stage. The duration of early life stages can vary
according to fish species. The department considers the sources of information
in subdivisions 1 a (1) through (5) of this subsection to be the only
acceptable sources of information for determining the duration of early life
stages of fish under this procedure.
3. "Occur at the site" includes the species,
genera, families, orders, classes, and phyla that are usually present at the
site; are present at the site only seasonally due to migration; are present
intermittently because they periodically return to or extend their ranges into
the site; or were present at the site in the past or are present in nearby
bodies of water, but are not currently present at the site due to degraded
conditions, and are expected to return to the site when conditions improve.
"Occur at the site" does not include taxa that were once present at the site
but cannot exist at the site now due to permanent physical alteration of the
habitat at the site.
4. Any
modifications to ambient water quality criteria for ammonia in subdivision 1 of
this subsection shall not likely jeopardize the continued existence of any
federal or state listed, threatened, or endangered species or result in the
destruction or adverse modification of such species' critical
habitats.
5. Site-specific
modifications to the ambient water quality criteria for ammonia to account for
the absence of freshwater mussels shall be conducted in accordance with the
procedures contained in this subsection. Because the department presumes that
most state waterbodies have freshwater mussel species, the criteria shall be
calculated assuming mussels are present using subsections B and C of this
section unless the demonstration that freshwater mussels are absent is
successfully completed and accepted by DEQ and the Department of Wildlife
Resources.
6. Equations for
calculating ammonia criteria for four different site-specific scenarios are
provided in subdivisions 6 a through d of this subsection as follows:
(i) acute criteria when mussels are absent
but trout are present,
(ii) acute
criteria when mussels and trout are absent,
(iii) chronic criteria when mussels are
absent and early life stages of fish are present, and
(iv) chronic criteria when mussels and early
life stages of fish are absent. Additional information regarding site-specific
criteria can be reviewed in appendix N (pages 225-242) of the EPA Aquatic Life
Ambient Water Quality Criteria to Ammonia--Freshwater 2013 (EPA 822-R-13-001).
a. Acute criteria: freshwater mussels absent
and trout present. To calculate total ammonia nitrogen acute criteria values
(in mg N/L) in freshwater with freshwater mussels absent (procedures for making
this determination are in subdivisions 1 through 5 of this subsection) and
trout present, use the following equations . The acute criterion is the lesser
of the following calculation results . Round the result to two significant
digits.
(
|
0.275
|
+
|
39
|
)
|
1 +
107.204-pH
|
1 +
10pH-7.204
|
or
0.7249 X (
|
0.0114
|
+
|
1.6181
|
) X (62.15 X 100.036X(20 °
T))
|
1 +
107.204-pH
|
1 +
10pH-7.204
|
b.
Acute criteria: freshwater mussels absent and trout absent. To calculate total
ammonia nitrogen acute criteria values (in mg N/L) in freshwater where
freshwater mussels are absent and trout are absent, use the following equation.
Round the result to two significant digits.
0.7249 X (
|
0.0114
|
+
|
1.6181
|
) X MIN
|
1 +
107.204-pH
|
1 +
10pH-7.204
|
Where MIN = 51.93 or 62.15 X 100.036 X (20
-T), whichever is less
T = Temperature in
oC
c. Chronic criteria: freshwater mussels
absent and early life stages of fish present. The chronic criteria for total
ammonia nitrogen (in mg N/L) where freshwater mussels are absent (procedures
for making this determination are in subdivisions 1 through 5 of this
subsection) in freshwater shall not exceed concentration values calculated
using the following equation. Round the result to two significant digits.
0.9405 X (
|
0.0278
|
+
|
1.1994
|
) X MIN
|
1 +
107.688-pH
|
1 +
10pH-7.688
|
Where MIN = 6.920 or 7.547 X 100.028 x (20 -
T) whichever is less
T = temperature in °C
d. Chronic criteria: freshwater mussels
absent and early life stages of fish absent. The chronic criteria for total
ammonia nitrogen (in mg N/L) where freshwater mussels are absent and early life
stages of fish are absent (procedures for making this determination are in
subdivisions 1 through 5 of this subsection) in freshwater shall not exceed
concentration values calculated using the following equation . Round the result
to two significant digits.
0.9405 X (
|
0.0278
|
+
|
1.1994
|
) X(7.547 X 100.028 X (20
-MAX(T,7)))
|
1 +
107.688-pH
|
1 +
10pH-7.688
|
Where MAX = 7 or temperature in degrees Celsius, whichever
is greater
T = temperature in °C
E. The one-hour average
concentration of total ammonia nitrogen (in mg N/L) in saltwater shall not
exceed, more than once every three years on the average, the acute criteria in
the following table:
Acute Ammonia Saltwater Criteria
Total Ammonia Nitrogen (mg N/L)
Salinity = 10 g/kg
|
Temperature °C
|
pH
|
0
|
5
|
10
|
15
|
20
|
25
|
30
|
35
|
7.00
|
231.9
|
159.8
|
110.1
|
75.88
|
52.31
|
36.08
|
24.91
|
17.21
|
7.20
|
146.4
|
100.9
|
69.54
|
47.95
|
33.08
|
22.84
|
15.79
|
10.93
|
7.40
|
92.45
|
63.73
|
43.94
|
30.32
|
20.94
|
14.48
|
10.03
|
6.97
|
7.60
|
58.40
|
40.28
|
27.80
|
19.20
|
13.28
|
9.21
|
6.40
|
4.47
|
7.80
|
36.92
|
25.48
|
17.61
|
12.19
|
8.45
|
5.88
|
4.11
|
2.89
|
8.00
|
23.37
|
16.15
|
11.18
|
7.76
|
5.40
|
3.78
|
2.66
|
1.89
|
8.20
|
14.81
|
10.26
|
7.13
|
4.97
|
3.48
|
2.46
|
1.75
|
1.27
|
8.40
|
9.42
|
6.54
|
4.57
|
3.20
|
2.27
|
1.62
|
1.18
|
0.87
|
8.60
|
6.01
|
4.20
|
2.95
|
2.09
|
1.50
|
1.09
|
0.81
|
0.62
|
8.80
|
3.86
|
2.72
|
1.93
|
1.39
|
1.02
|
0.76
|
0.58
|
0.46
|
9.00
|
2.51
|
1.79
|
1.29
|
0.95
|
0.71
|
0.55
|
0.44
|
0.36
|
Salinity = 20 g/kg
|
|
Temperature °C
|
pH
|
0
|
5
|
10
|
15
|
20
|
25
|
30
|
35
|
7.00
|
247.6
|
170.5
|
117.5
|
80.98
|
55.83
|
38.51
|
26.58
|
18.36
|
7.20
|
156.3
|
107.7
|
74.21
|
51.17
|
35.30
|
24.37
|
16.84
|
11.66
|
7.40
|
98.67
|
68.01
|
46.90
|
32.35
|
22.34
|
15.44
|
10.70
|
7.43
|
7.60
|
62.33
|
42.98
|
29.66
|
20.48
|
14.17
|
9.82
|
6.82
|
4.76
|
7.80
|
39.40
|
27.19
|
18.78
|
13.00
|
9.01
|
6.26
|
4.37
|
3.07
|
8.00
|
24.93
|
17.23
|
11.92
|
8.27
|
5.76
|
4.02
|
2.83
|
2.01
|
8.20
|
15.80
|
10.94
|
7.59
|
5.29
|
3.70
|
2.61
|
1.86
|
1.34
|
8.40
|
10.04
|
6.97
|
4.86
|
3.41
|
2.41
|
1.72
|
1.24
|
0.91
|
8.60
|
6.41
|
4.47
|
3.14
|
2.22
|
1.59
|
1.15
|
0.85
|
0.65
|
8.80
|
4.11
|
2.89
|
2.05
|
1.47
|
1.07
|
0.80
|
0.61
|
0.48
|
9.00
|
2.67
|
1.90
|
1.36
|
1.00
|
0.75
|
0.57
|
0.46
|
0.37
|
Salinity = 30 g/kg
|
Temperature °C
|
pH
|
0
|
5
|
10
|
15
|
20
|
25
|
30
|
35
|
7.00
|
264.6
|
182.3
|
125.6
|
86.55
|
59.66
|
41.15
|
28.39
|
19.61
|
7.20
|
167.0
|
115.1
|
79.31
|
54.68
|
37.71
|
26.03
|
17.99
|
12.45
|
7.40
|
105.5
|
72.68
|
50.11
|
34.57
|
23.87
|
16.50
|
11.42
|
7.92
|
7.60
|
66.61
|
45.93
|
31.69
|
21.88
|
15.13
|
10.48
|
7.28
|
5.07
|
7.80
|
42.10
|
29.05
|
20.07
|
13.88
|
9.62
|
6.68
|
4.66
|
3.27
|
8.00
|
26.63
|
18.40
|
12.73
|
8.83
|
6.14
|
4.29
|
3.01
|
2.13
|
8.20
|
16.88
|
11.68
|
8.10
|
5.64
|
3.94
|
2.78
|
1.97
|
1.42
|
8.40
|
10.72
|
7.44
|
5.18
|
3.63
|
2.56
|
1.82
|
1.31
|
0.96
|
8.60
|
6.83
|
4.77
|
3.34
|
2.36
|
1.69
|
1.22
|
0.90
|
0.68
|
8.80
|
4.38
|
3.08
|
2.18
|
1.56
|
1.13
|
0.84
|
0.64
|
0.50
|
9.00
|
2.84
|
2.01
|
1.45
|
1.06
|
0.79
|
0.60
|
0.47
|
0.39
|
To calculate total ammonia nitrogen acute criteria values
in saltwater at different pH and temperature values than those listed in this
subsection, use the following formulas:
I =
|
19.9273S
|
(1000 - 1.005109S)
|
Where I = molal ionic strength of water
S = Salinity ppt (g/kg)
The regression model used to relate I to pKa (negative log
of the ionization constant) is
pKa = 9.245 + 0.138(I)
pKa as defined by these equations is at 298 degrees Kelvin
(25°C).
T °Kelvin = °C + 273
To correct for other temperatures:
pKaST =
pKaS298 + 0.0324(298 - T
°Kelvin)
The unionized ammonia fraction (UIA) is given by:
The acute ammonia criterion in saltwater is given
by:
Multiply the acute value by 0.822 to get the ammonia-N
acute criterion.
F. The
30-day average concentration of total ammonia nitrogen (in mg N/L) in saltwater
shall not exceed, more than once every three years on the average, the chronic
criteria in the following table:
Chronic Ammonia Saltwater Criteria
Total Ammonia Nitrogen (mg N/L)
Salinity = 10 g/kg
|
pH
|
Temperature °C
|
0
|
5
|
10
|
15
|
20
|
25
|
30
|
35
|
7.00
|
34.84
|
24.00
|
16.54
|
11.40
|
7.86
|
5.42
|
3.74
|
2.59
|
7.20
|
21.99
|
15.15
|
10.45
|
7.20
|
4.97
|
3.43
|
2.37
|
1.64
|
7.40
|
13.89
|
9.57
|
6.60
|
4.55
|
3.15
|
2.18
|
1.51
|
1.05
|
7.60
|
8.77
|
6.05
|
4.18
|
2.88
|
2.00
|
1.38
|
0.96
|
0.67
|
7.80
|
5.55
|
3.83
|
2.65
|
1.83
|
1.27
|
0.88
|
0.62
|
0.43
|
8.00
|
3.51
|
2.43
|
1.68
|
1.17
|
0.81
|
0.57
|
0.40
|
0.28
|
8.20
|
2.23
|
1.54
|
1.07
|
0.75
|
0.52
|
0.37
|
0.26
|
0.19
|
8.40
|
1.41
|
0.98
|
0.69
|
0.48
|
0.34
|
0.24
|
0.18
|
0.13
|
8.60
|
0.90
|
0.63
|
0.44
|
0.31
|
0.23
|
0.16
|
0.12
|
0.09
|
8.80
|
0.58
|
0.41
|
0.29
|
0.21
|
0.15
|
0.11
|
0.09
|
0.07
|
9.00
|
0.38
|
0.27
|
0.19
|
0.14
|
0.11
|
0.08
|
0.07
|
0.05
|
Salinity = 20 g/kg
|
Temperature °C
|
pH
|
0
|
5
|
10
|
15
|
20
|
25
|
30
|
35
|
7.00
|
37.19
|
25.62
|
17.65
|
12.16
|
8.39
|
5.78
|
3.99
|
2.76
|
7.20
|
23.47
|
16.17
|
11.15
|
7.69
|
5.30
|
3.66
|
2.53
|
1.75
|
7.40
|
14.82
|
10.22
|
7.04
|
4.86
|
3.36
|
2.32
|
1.61
|
1.12
|
7.60
|
9.36
|
6.46
|
4.46
|
3.08
|
2.13
|
1.47
|
1.02
|
0.71
|
7.80
|
5.92
|
4.08
|
2.82
|
1.95
|
1.35
|
0.94
|
0.66
|
0.46
|
8.00
|
3.74
|
2.59
|
1.79
|
1.24
|
0.86
|
0.60
|
0.43
|
0.30
|
8.20
|
2.37
|
1.64
|
1.14
|
0.79
|
0.56
|
0.39
|
0.28
|
0.20
|
8.40
|
1.51
|
1.05
|
0.73
|
0.51
|
0.36
|
0.26
|
0.19
|
0.14
|
8.60
|
0.96
|
0.67
|
0.47
|
0.33
|
0.24
|
0.17
|
0.13
|
0.10
|
8.80
|
0.62
|
0.43
|
0.31
|
0.22
|
0.16
|
0.12
|
0.09
|
0.07
|
9.00
|
0.40
|
0.28
|
0.20
|
0.15
|
0.11
|
0.09
|
0.07
|
0.06
|
Salinity = 30 g/kg
|
Temperature °C
|
pH
|
0
|
5
|
10
|
15
|
20
|
25
|
30
|
35
|
7.00
|
39.75
|
27.38
|
18.87
|
13.00
|
8.96
|
6.18
|
4.27
|
2.95
|
7.20
|
25.09
|
17.29
|
11.91
|
8.21
|
5.67
|
3.91
|
2.70
|
1.87
|
7.40
|
15.84
|
10.92
|
7.53
|
5.19
|
3.59
|
2.48
|
1.72
|
1.19
|
7.60
|
10.01
|
6.90
|
4.76
|
3.29
|
2.27
|
1.57
|
1.09
|
0.76
|
7.80
|
6.32
|
4.36
|
3.01
|
2.08
|
1.44
|
1.00
|
0.70
|
0.49
|
8.00
|
4.00
|
2.76
|
1.91
|
1.33
|
0.92
|
0.64
|
0.45
|
0.32
|
8.20
|
2.53
|
1.75
|
1.22
|
0.85
|
0.59
|
0.42
|
0.30
|
0.21
|
8.40
|
1.61
|
1.12
|
0.78
|
0.55
|
0.38
|
0.27
|
0.20
|
0.14
|
8.60
|
1.03
|
0.72
|
0.50
|
0.35
|
0.25
|
0.18
|
0.14
|
0.10
|
8.80
|
0.66
|
0.46
|
0.33
|
0.23
|
0.17
|
0.13
|
0.10
|
0.08
|
9.00
|
0.43
|
0.30
|
0.22
|
0.16
|
0.12
|
0.09
|
0.07
|
0.06
|
To calculate total ammonia nitrogen chronic criteria values
in saltwater at different pH and temperature values than those listed in this
subsection, use the following formulas:
I =
|
19.9273S
|
(1000 - 1.005109S)
|
Where I = molal ionic strength of water
S = Salinity ppt (g/kg)
The regression model used to relate I to pKa (negative log
of the ionization constant) is
pKa = 9.245 + 0.138(I)
pKa as defined by these equations is at 298 degrees Kelvin
(25°C).
T °Kelvin = °C + 273
To correct for other temperatures:
pKaST =
pKaS298 + 0.0324(298 - T
°Kelvin)
The unionized ammonia fraction (UIA) is given by:
The chronic ammonia criterion in saltwater is given
by:
Multiply the chronic value by 0.822 to get the ammonia-N
chronic criterion.
G.
Implementation of freshwater ammonia water quality criteria in subsections B
and C of this section through VPDES permits issued pursuant to Virginia
Pollutant Discharge Elimination System (VPDES) Permit Regulation (9VAC
25-31).
1. The criteria in subsections B and C of
this section shall be implemented in VPDES permits that are being reissued to
facilities in accordance with the following schedule:
a. Major municipal facilities with design
flows greater than or equal to five million gallons per day and major
industrial facilities - 12 months following the Water Quality Standards
effective date.
b. Municipal
facilities with design flows greater than or equal to 500,000 gallons per day
and less than five million gallons per day and all minor industrial facilities
- 24 months following the Water Quality Standards effective date.
c. Minor municipal facilities with design
flows that are less than 500,000 gallons per day - 36 months following the
Water Quality Standards effective date.
2. VPDES permits shall not be revoked and
reissued to avoid or delay being subject to the freshwater ammonia water
quality criteria in subsections B and C of this section in accordance with the
schedule in subdivision G 1 of this section.
3. The provisions of
9VAC25-31-250
A 3 notwithstanding, a permittee may request and the board may authorize, as
appropriate, an extended schedule of compliance, which exceeds the term of the
VPDES permit and may include multiple permit cycles to achieve effluent limits
based on the freshwater ammonia water quality criteria in subsections B and C
of this section.
a. Any extended schedule of
compliance necessary for the implementation of the freshwater ammonia water
quality criteria shall require compliance as soon as possible in accordance
with
9VAC25-31-250
A 1. The board may consider the following factors on a case-by-case basis,
relying on information provided by the permittee, in making a determination of
the timeframe that meets the standard of "as soon as possible":
(1) The relative priority of freshwater
ammonia water quality criteria and other water quality and water infrastructure
needs of the local community or permittee;
(2) Availability of grant funding pursuant to
§
10.1-2131
of the Code of Virginia and other treatment facility expansion and upgrade
plans;
(3) Whether an extended
schedule of compliance is appropriate for facilities or classes of facilities;
and
(4) Appropriate mechanisms to
address affordability limitations and financial hardship situations remaining
notwithstanding subdivisions G 1 a, G 1 b, and G 1 c of this section.
b. Any request by the permittee
for an extended schedule of compliance shall include at the time of permit
application at a minimum the following information:
(1) Documentation of other water quality and
water infrastructure projects that are in the planning, design, or construction
process and the relative priority of the projects in relation to compliance
with the freshwater ammonia water quality criteria.
(2) A preliminary engineering analysis of
treatment facility upgrade or source reduction alternatives necessary to meet
the freshwater ammonia criteria. The analysis may include any additional
upgrade or expansion plans currently under consideration. The analysis shall be
prepared by a professional engineer registered in Virginia and shall include an
estimation of the capital and operations and maintenance costs.
(3) An assessment of project affordability
and identification of all potential sources of funding for enhanced ammonia
treatment. In the case of publicly owned treatment works, include an evaluation
of the required sewer use fees versus median household income.
(4) Documentation that demonstrates the
minimum estimated time required and schedule to design, fund, and construct the
selected treatment or source reduction alternative.
(5) An evaluation prepared by a professional
engineer registered in Virginia of the highest achievable condition (HAC)
regarding nitrification capabilities of the existing treatment facility under
the influent loading conditions expected during the term of the VPDES permit as
well as under design loading conditions.
c. Any VPDES permit that authorizes an
extended schedule of compliance for meeting the freshwater ammonia water
quality criteria that exceeds the permit term shall include interim effluent
limitations based on the HAC attainable during the term of the permit, final
effluent limitations, and a final compliance date.
d. New dischargers defined in 9VAC
25-31 are
not eligible for extended schedules of compliance under this section; however,
they remain eligible for schedules of compliance consistent with
9VAC25-31-250.
A permittee may seek a site-specific modification or
variance to the freshwater ammonia water quality criteria under
9VAC25-260-140
D or E as applicable.