301(h) Tentative Decision: AK0021466
City of Wrangell Wastewater Treatment Plant
Application For A Modified NPDES Permit Under Section 301(h) Of
The Clean Water Act
Tentative Decision Document
October 2022
United States Environmental Protection Agency
Region 10
1200 6th Avenue
Seattle, WA 98101
-------
301(h) Tentative Decision: AK0021466
Contents
1) Introduction 5
2) Decision Criteria 5
3) SUMMARY OF FINDINGS 8
4) DECISION AND RECOMMENDATION 9
5) DESCRIPTION OF TREATMENT SYSTEM 9
6) DESCRIPTION OF RECEIVING WATERS 9
A. General Features 9
B. Currents and Flushing 10
7) PHYSICAL CHARACTERISTICS OF THE DISCHARGE 10
A. Outfall/Diffuser Design and Initial Dilution 10
8) APPLICATION OF STATUTORY AND REGULATORY CRITERIA 11
A. Compliance with Primary or Equivalent Treatment Requirements
[CWA Section 301(h)(9); 40 CFR 125.60] 11
1. Total Suspended Solids 11
2. Biochemical Oxygen Demand 13
B. ATTAINMENT OF WATER QUALITY STANDARDS RELATED TO TSS AND BOD5
[CWA § 301(h)(1); 40 CFR § 125.61] 15
1. Turbidity and Light Transmittance/Attenuation 15
2. Dissolved Oxygen 17
C. Attainment of Other Water Quality Standards and Impact Of the Discharge On Shellfish, Fish
And Wildlife; Public Water Supplies; And Recreation
[CWA Section 301(h)(2); 40 CFR 125.62] 19
1. pH 19
2. Temperature 20
3. Toxics 20
4. Bacteria 20
D. Impact of the Discharge on Public Water Supplies [40 CFR § 125.62(b)] 23
E. Biological Impact of Discharge [40 CFR § 125.62(c)] 23
F. Impact of Discharge on Recreational Activities [40 CFR § 125.62(d)] 23
G. Establishment of Monitoring Programs [CWA § 301(h)(3); 40 CFR §125.63] 24
1. Influent/Effluent Monitoring Program [40 CFR §125.63(d)] 24
2. Receiving Water Quality Monitoring Program [40 CFR §125.63(c)] 24
-------
301(h) Tentative Decision: AK0021466
3. Biological Monitoring Program [40 CFR §125.63(b)] 25
H. Effect of Discharge on Other Point and Nonpoint Sources [CWA § 301(h)(4); 40 CFR §125.64].. 25
I. Urban Area Pretreatment Program [CWA § 301(h)(6); 40 CFR §125.65] 25
J. Toxics Control Program [CWA § 301(h)(7); 40 CFR §125.66] 26
1. Chemical Analysis and Toxic Pollutant Source Identification [40 CFR §§125.66(a) and (b)] 26
2. Industrial Pretreatment Program [40 CFR §125.66(c)] 26
3. Nonindustrial Source Control Program [40 CFR §125.66(d)] 26
K. Effluent Volume and Amount of Pollutants Discharged [40 CFR § 125.67] 26
L. COMPLIANCE WITH OTHER APPLICABLE LAWS [40 CFR § 125.59] 27
1. Coastal Zone Management Act 27
2. Marine Protection, Research, and Sanctuaries Act 27
3. Endangered or Threatened Species 27
4. Essential Fish Habitat 28
M. STATE DETERMINATION AND CONCURRENCE [40 CFR § 125.61(b)(2); 40 CFR § 125.64(d)] 28
9) References 29
10) Appendices 30
A. Facility Figures and Process Flow Diagram 30
B. Outfall Location and Receiving Water Monitoring Maps 32
Figure 1 34
Figure 2 35
C. Summary Statistics of Discharge Monitoring Data (2016-2021) 36
D. Alaska WQS 37
E. Equations and Analysis 42
1. Section 8.B.1: Attainment of TSS Standard 42
2. Section 8.B.2: Attainment of DO Standard 42
3. Section 8.C.3. Toxics Analysis 43
F. TVS Survey Results 46
G. Dilution Modeling Report 47
-------
301(h) Tentative Decision: AK0021466
-------
301(h) Tentative Decision: AK0021466
1) Introduction
The City of Wrangell, Alaska, ("the City," "the applicant," "Wrangell," or "the permittee") has requested a
renewal of its variance (sometimes informally called a "waiver" or "modification") under Section 301(h) of the
Clean Water Act (the Act or CWA), 33 USC § 1311(h), from the secondary treatment requirements contained in
Section 301(b)(1)(B) of the Act, 33 USC § 1311(b)(1)(B).
EPA approved the City of Wrangell's first request for modification of secondary treatment requirements and
issued its first CWA Section 301(h)-modified NPDES permit on October 6,1983 [AK0021466]. The most recent
NPDES permit was issued on December 4, 2001, became effective on January 7, 2002, and expired on January
8, 2007 (hereinafter, referred to as the 2002 permit). A timely and complete NPDES application for permit
reissuance was submitted by the permittee on April 25, 2006. Pursuant to Title 40 CFR Part 122.6, the permit
has been administratively continued and remains fully effective and enforceable.
The variance is being sought for the City of Wrangell's Wastewater Treatment Plant ("WWTP" or "the
facility"), a publicly owned treatment works (POTW). The applicant is seeking a 301(h) variance to discharge
wastewater receiving less-than-secondary treatment from a single outfall into Zimovia Straight. The effluent
quality attainable by secondary treatment is defined in regulations at 40 Code of Federal Regulations (CFR)
Part 133 in terms of BOD5, TSS, and pH. Pursuant to 40 CFR Part 133.102, secondary treatment requirements
forTSS, BODs, and pH are as follows:
TSS: (1) The 30-day average concentration shall not exceed 30 mg/l;
(2) The 7-day average concentration shall not exceed 45 mg/l; and
(3) The 30-day average percent removal shall not be less than 85%.
BOD5: (1) The 30-day average concentration shall not exceed 30 mg/l;
(2) The 7-day average concentration shall not exceed 45 mg/l; and
(3) The 30-day average percent removal shall not be less than 85%.
pH: The pH of the effluent shall be maintained within the limits of 6.0 to 9.0 pH standard units.
The City requested a modification forTSS and BOD5, but not pH.
This document presents EPA Region 10's tentative findings, conclusions, and recommendations as to whether
the applicant's proposed 301(h)-modified discharge (proposed discharge) will comply with the criteria set
forth in sections 301(h) of the Act, as implemented by regulations at 40 CFR 125, Subpart G, and Alaska Water
Quality Standards (Alaska WQS), as amended.
2) Decision Criteria
Under Section 301(b)(1)(B) of the Act, 33 USC § 1311(b)(1)(B), POTWs in existence on July 1, 1977, are
required to meet effluent limits based on secondary treatment as defined by the Administrator of EPA ("the
Administrator"). Secondary treatment is defined by the Administrator in terms of three parameters: TSS,
BOD5, and pH. Uniform national effluent limitations for these pollutants were promulgated and included in
National Pollutant Discharge Elimination System (NPDES) permits for POTWs issued under Section 402 of the
CWA. POTWs were required to comply with these limitations by July 1, 1977.
-------
301(h) Tentative Decision: AK0021466
Congress subsequently amended the Act, adding Section 301(h) which authorizes the Administrator, with
State concurrence, to issue NPDES permits that modify the secondary treatment requirements of the Act with
respect to certain discharges. P.L. 95-217, 91 Stat. 1566, as amended by P.L. 97-117, 95 Stat. 1623; and S303 of
the Water Quality Act of 1987. Section 301(h) provides that:
[T]he Administrator, with the concurrence of the State, may issue a permit under section 402 [of
the Act] which modifies the requirements of subsection (b)(1)(B) of this section [the secondary
treatment requirements] with respect to the discharge of any pollutant from a publicly owned
treatment works into marine waters, if the applicant demonstrates to the satisfaction of the
Administrator that:
(1) there is an applicable water quality standard specific to the pollutant for which the modification
is requested, which has been identified under section 304(a)(6) of [the CWA];
(2) the discharge of pollutants in accordance with such modified requirements will not interfere,
alone or in combination with pollutants from other sources, with the attainment or
maintenance of that water quality which assures protection of public water supplies and the
protection and propagation of a balanced, indigenous population of shellfish, fish and wildlife,
and allows recreational activities, in and on the water;
(3) the applicant has established a system for monitoring the impact of such discharge on a
representative sample of aquatic biota, to the extent practicable, and the scope of the
monitoring is limited to include only those scientific investigations which are necessary to study
the effects of the proposed discharge;
(4) such modified requirements will not result in any additional requirements on any other point or
nonpoint source;
(5) all applicable pretreatment requirements for sources introducing waste into such treatment
works will be enforced;
(6) in the case of any treatment works serving a population of 50,000 or more, with respect to any
toxic pollutant introduced into such works by an industrial discharger for which pollutant there
is no applicable pretreatment requirement in effect, sources introducing waste into such works
are in compliance with all applicable pretreatment requirements, the applicant has in effect a
pretreatment program which, in combination with the treatment of discharges from such works,
removes the same amount of such pollutant as would be removed if such works were to apply
secondary treatment to discharges and if such works had no pretreatment program with respect
to such pollutant;
(7) to the extent practicable, the applicant has established a schedule of activities designed to
eliminate the entrance of toxic pollutants from nonindustrial sources into such treatment works;
(8) there will be no new or substantially increased discharges from the point source of the pollutant
into which the modification applies above that volume of discharge specified in the permit; and
(9) the applicant at the time such modification becomes effective will be discharging effluent which
has received at least primary or equivalent treatment and which meets the criteria established
under [section 304(a)(1) of the CWA] after initial mixing in the waters surrounding or adjacent
to the point at which such effluent is discharged.
For the purposes of this subsection the phrase "the discharge of any pollutant into marine
waters" refers to a discharge into deep waters of the territorial sea or the waters of the
-------
301(h) Tentative Decision: AK0021466
contiguous zone, or into saline estuarine waters where there is strong tidal movement and other
hydrological and geological characteristics which the Administrator determines necessary to
allow compliance with paragraph (2) of this subsection, and [section 101(a)(2) of the Act]. For
the purposes of paragraph (9), "primary or equivalent treatment" means treatment by
screening, sedimentation, and skimming adequate to remove at least 30 percent of the
biological oxygen demanding material and of the suspended solids in the treatment works
influent, and disinfection, where appropriate. A municipality which applies secondary treatment
shall be eligible to receive a permit pursuant to this subsection which modifies the requirements
of subsection (b)(1)(B) of this section with respect to the discharge of any pollutant from any
treatment works owned by such municipality into marine waters. No permit issued under this
subsection shall authorize the discharge of sewage sludge into marine waters. In order for a
permit to be issued under this subsection for the discharge of a pollutant into marine waters,
such marine waters must exhibit characteristics assuring that water providing dilution does not
contain significant amounts of previous discharged effluent from such treatment works. No
permit issued under this subsection shall authorize the discharge of any pollutant into saline
estuarine waters which at the time of application do not support a balanced, indigenous
population of shellfish, fish and wildlife, or allow recreation in and on the waters or which
exhibit ambient water quality below applicable water quality standards adopted for the
protection of public water supplies, shellfish, fish and wildlife or recreational activities or such
other standards necessary to assure support and protection of such uses. The prohibition
contained in the preceding sentence shall apply without regard to the presence or absence of a
causal relationship between such characteristics and the applicant's current or proposed
discharge. Notwithstanding any of the other provisions of this subsection, no permit may be
issued under this subsection for discharge of a pollutant into the New York Bight Apex consisting
of the ocean waters of the Atlantic Ocean westward of 73 degrees 30 minutes west longitude
and westward of 40 degrees 10 minutes north latitude.
On August 9, 1994, EPA promulgated final regulations implementing these statutory criteria at 40 CFR Part
125, Subpart G. The regulations provide that a Section 301(h)-modified NPDES permit may not be issued in
violation of 40 CFR 125.59(b) which requires, among other things, compliance with provisions of the Coastal
Zone Management Act, as amended, 16 USC § 1451 etseq., the Endangered Species Act, as amended, 16 USC
§ 1531 etseq., Title III of the Marine Protection Research and Sanctuaries Act, as amended, 16 USC § 1431 et
seq., the Magnuson-Stevens Fishery Conservation and Management Act, as amended, 16 USC § 1801 et seq.,
and any other applicable provisions of local, state, and federal laws or Executive Orders.
In accordance with 40 CFR 125.59(i), the decision to grant or deny a CWA Section 301(h) waiver shall be made
by the Administrator and shall be based on the applicant's demonstration that it has met all the requirements
of 40 CFR 125.59 through 125.68, as described in this 301(h) Tentative Decision Document (301(h) TDD). EPA
has reviewed all data submitted by the applicant in the context of applicable statutory and regulatory criteria
and has presented its findings and conclusions in this 301(h) TDD.
-------
301(h) Tentative Decision: AK0021466
3) SUMMARY OF FINDINGS
Based upon review of the data, references, and empirical evidence furnished by the applicant and other
relevant sources, EPA Region 10 makes the following tentative findings regarding the statutory and regulatory
criteria:
1. The applicant's proposed discharge will comply with Alaska WQS for dissolved oxygen and turbidity.
[CWA Section 301(h)(1); 40 CFR 125.61]
2. The applicant has demonstrated it can consistently achieve Alaska WQS and federal CWA Section
304(a)(1) water quality criteria at and beyond the zone of initial dilution (ZID). [CWA Section 301(h)(9);
40 CFR 125.62(a)]
3. The applicant's proposed discharge, alone or in combination with pollutants from other sources, will
not adversely impact public water supplies or interfere with the protection and propagation of a
balanced, indigenous population (BIP) of shellfish, fish, and wildlife, and will allow for recreational
activities in an on the water. [CWA Section 301(h)(2); 40 CFR 125.62(b), (c), (d)]
4. The applicant has a well-established and adequate program to monitor the impact of its proposed
discharge on aquatic biota and has demonstrated it has adequate resources to continue the program.
These monitoring requirements will remain enforceable terms of the permit. [CWA Section 301(h)(3);
40 CFR 125.63]
5. The applicant's proposed discharge will not result in any additional treatment requirements on any
other point or nonpoint sources. The applicant sent a letter to the Alaska Department of
Environmental Conservation (ADEC) requesting concurrence with this determination. [CWA Section
301(h)(4); 40 CFR 125.64]
6. The applicant will continue to implement its nonindustrial source control program, consisting of public
outreach and education designed to minimize the amount of toxic pollutants that enter the treatment
system from nonindustrial sources. [CWA Section 301(h)(7); 40 CFR 125.66]
7. There will be no new or substantially increased discharges from the point source of the pollutants to
which the 301(h) variance applies above those specified in the permit. [CWA Section 301(h)(8); 40 CFR
125.67]
8. The discharge is not expected to conflict with applicable provisions of State, local, or other Federal
laws or Executive Orders, including compliance with the Coastal Zone Management Act of 1972, as
amended, 16 USC 1451 et seq.; the Endangered Species Act of 1973, as amended, 16 USC 1531 et seq.;
Title III of the Marine Protection, Research and Sanctuaries Act, as amended, 16 USC 1431 et seq.; and
the Magnuson-Stevens Fishery Conservation and Management Act, as amended, 16 USC § 1801 etseq.
9. The applicant has demonstrated the proposed discharge will comply with federal primary treatment
requirements. [CWA Section 301(h)(9); 40 CFR 125.60]
-------
301(h) Tentative Decision: AK0021466
4) DECISION AND RECOMMENDATION
EPA has concluded that the applicant's proposed discharge will comply with the requirements of CWA Section
301(h) and 40 CFR 125, Subpart G, and recommends that the applicant be granted a CWA Section 301(h)
variance in accordance with the above findings, contingent upon satisfaction of the following conditions:
1. All requirements determined necessary by ADEC as part of its final CWA Section 401 Certification to
ensure that the proposed discharge will comply with applicable provisions of State law, including WQS,
in accordance with Section 401 of the CWA and the regulations at 40 CFR 124.54 and 40 CFR
125.61(b)(2).
2. The determination by ADEC that the proposed discharge will not result in any additional treatment
requirements on any other point or nonpoint sources, in accordance with 40 CFR 125.64.
3. The determination by the National Marine Fisheries Service that issuance of a 301(h)-modified permit
will not jeopardize the continued existence of any threatened or endangered species or result in the
destruction of critical habitat and does not conflict with applicable provisions of the Magnuson-Stevens
Fishery Conservation and Management Act, as amended.
5) DESCRIPTION OF TREATMENT SYSTEM
The WWTP serves the community of Wrangell, Alaska, which has a population of approximately 2,100 people.
According to the facility, peak design flow is 0.131 m3/sec (3 mgd) and average daily design flow is 0.026
m3/sec (0.6 mgd). In accordance with 40 CFR 125.58(c) the facility is a "small applicant." The collection system
is a separate sanitary sewer system and effluent is entirely domestic in origin. The existing outfall (001)
discharges to Zimovia Straight approximately 1500 feet offshore at a depth of 100 feet below mean lower low
water (MLLW). The outfall location is at a lat/long of: 56.453298 -132.391262
Raw sewage enters the WWTP through a mechanical screen where solids are automatically removed and
bagged for disposal at the municipal landfill. Screened sewage then flows into a 3.6 mgd capacity aeration
basin with a retention time of six days. Aeration is provided by fine bubble membrane diffusers attached to
floating aeration chains which are moved across the basin by the air released from the diffusers. Aeration basin
wastewater flows over V-shaped weirs where it then moves through a settling basin that has a detention time of
two days. The effluent leaves the settling basin by gravity flow where it is then discharged into Zimovia Strait.
See Appendix A for facility figures, area maps, and the treatment process flow diagram.
6) DESCRIPTION OF RECEIVING WATERS
A. General Features
The WWTP discharges into the saline estuarine waters of Zimovia Straight, approximately 1500 feet from the
shore of Cemetery Point and Heritage Harbor off the west side of Wrangell Island, Alaska. Zimovia Straight is a
tidal estuary within the Alexander Archipelago east of Clarence Straight, bounded by Wrangell Island to the
east, Etolin and Woronkovski Islands to the west, and the Stikine River delta to the north. Surface water
densities near the outfall vary due to local freshwater inputs from nearby streams and rivers. The major
freshwater input is the Stikine River, which discharges an annualized average flow of 55,078 ft3/s, with the
maximum average monthly discharge of 134,000 ft3/s occurring in June (USGS 2019). The Stikine River also
-------
301(h) Tentative Decision: AK0021466
contributes a substantial volume of suspended sediment to the estuary, with concentrations exceeding 1000
mg/L and volumes in excess of 250,000 tons a day during spring run-off (USGS 2022)
Zimovia Straight is classified in Alaska WQS as classes IIA(l)(ii)(iii), B(l)(ii), C and D, for use in aquaculture,
seafood processing and industrial water supply, water contact and secondary recreation, growth and
propagation of fish, shellfish, aquatic life and wildlife, and harvesting for consumption of raw mollusks or
other raw aquatic life.
B. Currents and Flushing
According to NOAA, the mean tide range at Wrangell is 13.57 ft, with a diurnal range of 15.96 ft., and a mean
tide level of 8.29 ft. above MLLW (NOAA 2019a). At a monitoring station 1.6 miles east of Wrangell Harbor
(Station 1257), the average maximum flood current is 0.8 knots with a bearing of 050° (northeast); the average
minimum before flood is 0.1 knots with a bearing of 290° (west-northwest); and the average maximum ebb is
0.8 knots, with a bearing of 235° (southwest) (NOAA 2019b). It is likely local boundary conditions nearer to the
outfall (i.e., Wrangell Island) result in currents that flow predominantly northwest (flood) and southeast (ebb)
because local currents would be forced this direction by Wrangell Island.
7) PHYSICAL CHARACTERISTICS OF THE DISCHARGE
A. Outfall/Diffuser Design and Initial Dilution
Pursuant to 40 CFR 125.62(a)(1), the outfall and diffuser must be located and designed to provide adequate
initial dilution, dispersion, and transport of wastewater to meet all applicable WQS at and beyond the
boundary of the ZID during periods of maximum stratification and during other periods when discharge
characteristics, water quality, biological seasons, or oceanographic conditions indicate more critical situations
may exist.
The WWTP outfall and diffuser are made of 12-inch diameter high density polyethylene pipe. The outfall is
1500 feet in length from MLLW, terminating in a 240-foot diffuser. The depth of the outfall is 100 feet at
MLLW (i.e., on the bottom of Zimovia Strait). The diffuser has sixteen 12-inch ports spaced 16 feet apart on
alternate sides of the pipe.
Zone of Initial Dilution (ZID)
Section 301(h)(9) of the CWA and 40 CFR 125.62 require 301(h) discharges to meet state WQS and federal
304(a) criteria at the boundary of the ZID, which is the region of initial mixing surrounding or adjacent to the
end of the outfall pipe or diffuser ports. The ZID may not be larger than allowed by mixing zone restrictions in
applicable water quality standards. 40 CFR 125.58(dd). The dilution ratio achieved at the completion of initial
mixing at the edge of the ZID is used to determine compliance with these requirements. Dilution is defined as
the ratio of the total volume of the sample (ambient water plus effluent) to the volume of effluent in the
sample. The ZID is not intended to describe the area bounding the entire mixing process or the total area
impacted. Rather, the ZID, or region of initial mixing is the area of rapid, turbulent mixing of the effluent and
receiving water and results from the interaction between the buoyancy and momentum of the discharge and
the density and momentum of the receiving water. Initial dilution is normally complete within several minutes
after discharge. In guidance EPA has operationally delimited the ZID to include the bottom area within a
-------
301(h) Tentative Decision: AK0021466
horizontal distance equal to the water depth from any point on the diffuser and the water column above that
area. USEPA 1994. Beyond the ZID boundary (i.e., after initial mixing is complete) the effluent is diluted further
by passive diffusion processes and far-field ambient receiving water conditions. The ZID is not inclusive of this
far-field mixing process.
The 2002 permit used a dilution factor of 880:1. EPA was unable to recreate this dilution factor using available
effluent and receiving water data.
EPA modeled the current discharge to determine the dilution achieved at the edge of the ZID using recent
effluent and receiving water data provided by the applicant (2016-2021). In accordance with the 301(h) TSD,
EPA used data reflecting critical discharge and receiving water conditions to determine dilution under critical
conditions. The dilution modeling report is included in Appendix G.
According to the model the discharge achieves initial mixing and a dilution of 112:1 about 40 feet from the
outfall at a depth of approximately 80 feet within two minutes of discharge under critical discharge and
receiving water conditions. EPA used 112:1 dilution as the basis for determining compliance with 301(h)(9)
and 40 CFR 125.62. Consistent with the recommendations in the 301(h) TSD for setting spatial boundaries for
the ZID, EPA has established the spatial dimensions of the ZID to include the entire water column within 100
feet of any point of the 240-foot diffuser. This is the same ZID spatial boundary as the 2002 permit. In its draft
401 certification ADEC authorized acute and chronic dilution factors of 3.9:1 and 29:1, respectively. These
dilutions fall within the boundary of the ZID.
8) APPLICATION OF STATUTORY AND REGULATORY CRITERIA
The sections below describe the statutory and regulatory requirements of 301(h) discharges and explains the
basis for the permit conditions.
A. Compliance with Primary or Equivalent Treatment Requirements
[CWA Section 301(h)(9); 40 CFR 125.60]
Under CWA Section 301(h)(9) and 40 CFR 125.60, the applicant must demonstrate it will be discharging
effluent that has received at least primary or equivalent treatment at the time the 301(h)-modified permit
becomes effective. 40 CFR 125.58(r) defines primary or equivalent treatment as treatment by screening,
sedimentation, and skimming adequate to remove at least 30 percent of the biochemical oxygen demanding
material and other suspended solids in the treatment works influent, and disinfection, where appropriate. To
ensure the effluent has received primary or equivalent treatment, the regulation at 40 CFR 125.60 requires
the applicant to perform monitoring of their influent and effluent and assess BODs and TSS removal rates
based on a monthly average.
Applicants for 301(h) waivers request concentration and loading (lb/day) limits for BOD5 and TSS based on
what the facility can achieve. Therefore, the technology-based requirements for POTWs with 301(h) waivers
are established on a case-by-case basis taking into consideration best professional judgement (BPJ), facility
performance, the federal primary treatment standards, and state WQS.
1. Total Suspended Solids
EPA reviewed influent and effluent monitoring data for TSS between 2016 and 2021. A summary table and
graphical representation of the data is provided below.
-------
301(h) Tentative Decision: AK0021466
f
TSS (mg/L)
300
250
200
150
100
50 \
0
!1 il_f
rgP
&
/
Influent (mg/L)
Effluent (mg/L)
Permit Limit (Ave Monthly) Permit Limit (Max Daily)
J-
Figure 2: Monthly Influent and Effluent TSS Concentrations (mg/L)
The facility has achieved the minimum 30% removal requirement for TSS 100% of the time, with the lowest
monthly removal being 42%. Between 2016 and 2021 the facility achieved an average of nearly 80% removal
of TSS, with maximum percent removal efficiencies as high as 97%.
-------
301(h) Tentative Decision: AK0021466
Table 1: INFLUENT AND EFFLUENT TSS DATA (2016-2021)
Statistic
Influent, TSS,
mg/L, Mo. Avg
Effluent, TSS,
mg/L, Max Daily1
Effluent, TSS,
mg/L, Mo. Avg1
Percent
Removal
LIMIT
—
200
140
>30%
COUNT
68
68
68
68
MEAN
86.8
13.9
13.9
78.9
MINIMUM
27
4
4
42
MAX
280
48
48
96.7
STDV
48.6
6.43
6.43
12
CV
0.56
0.46
0.46
0.15
5th
32.9
4.8
4.8
59
95th
185.5
24.1
24.1
95.6
1) The 2002 permit required monthly influent/effluent TSS monitoring, so maximum and average reported values are identical
The applicant has demonstrated it will be discharging effluent that has received at least primary or equivalent
treatment when the 301(h)-modified permit becomes effective [301(h)(9) and 40 CFR 125.60].
2. Biochemical Oxygen Demand
EPA reviewed influent and effluent data for BODs between 2016 and 2021. A summary table and graphical
representation of the data is provided below.
BOD5 (mg/L)
Percent Removal (BOD5) Primary Treatment Standard
v *
Figure 3: Minimum Monthly BOD5 Removal (2016-2021)
-------
301(h) Tentative Decision: AK0021466
r ~s
BOD5 (mg/L)
Influent (mg/L) Effluent (mg/L)
Permit Limit (Ave Monthly) Permit Limit (Max Daily)
^ J
Figure 4: Monthly Influent and Effluent BOD5 Concentrations (2016-2021)
The facility has achieved the minimum 30% removal requirement for BOD5 nearly 100% of the time, with one
month below 30% removal (28.5%, November 2019). Between 2016 and 2021 the facility achieved an average
of 77.6% removal of BOD5, with maximum percent removal efficiencies as high as 94.2%.
Table 2: INFLUENT AND EFFLUENT BOD5 DATA (2016-2021)
Statistic
Influent, BOD5, mg/L,
Mo. Avg
Effluent, BODs,
mg/L, Max Daily1
Effluent, BODs,
mg/L, Mo. Avg1
Percent
Removal
LIMIT
—
200
120
>30%
COUNT
68
68
68
68
MEAN
92.5
18.42
18.42
77.6
MIN
32
8.4
8.4
28.5
MAX
240
100
100
94.2
STDV
46.7
11.75
11.75
10.6
CV
0.50
0.64
0.64
0.14
5th
37.5
9.9
9.9
60.3
95th
185.5
33.6
33.6
89.7
1) The 2002 permit required monthly influent/effluent BOD5 monitoring, so reported values for maximum and
average are identical
The applicant has demonstrated it will be discharging effluent that has received at least primary or equivalent
treatment when the 301(h)-modified permit becomes effective [301(h)(9) and 40 CFR 125.60].
-------
301(h) Tentative Decision: AK0021466
B. ATTAINMENT OF WATER QUALITY STANDARDS RELATED TO TSS AND BODb
[CWA § 301(h)(1); 40 CFR § 125.61]
Under 40 CFR 125.61, which implements Section 301(h)(1), there must be water quality standards applicable to the
pollutants for which the modification is requested, and the applicant must demonstrate that the proposed
discharge will comply with these standards. The applicant has requested modified secondary treatment
requirements for BODs, which affects dissolved oxygen (DO), and TSS, which affects the color or turbidity in the
receiving water. The State of Alaska has water quality standards for DO and turbidity.
1. Turbidity and Light Transmittance/Attenuation
Alaska WQS applicable to the estuarine waters of Zimovia Strait provide that turbidity shall not exceed 25
nephelometric turbidity units (NTU), may not interfere with disinfection, may not cause detrimental effect on
established levels of water supply treatment, and may not reduce the depth of the compensation point for
photosynthetic activity by more than 10% (Table X). In addition, turbidity may not reduce the maximum secchi disc
depth by more than 10%. Alaska WQS for turbidity can be found in Appendix E.
The applicant has been collecting annual receiving water data for turbidity and secchi depth. Sampling is
conducted in August at the surface, mid-depth, and bottom of the receiving water at the following sites:
Site 1:1000 feet northwest of the ZID
Site 2:1000 feet southeast of the ZID
Site 3: <5 meters northwest of the ZID boundary
Site 4: <5 meters southeast of the ZID boundary
Sites 1 and 2 are considered reference sites and sites 3 and 4 are boundary sites of the ZID. Monitoring results
are presented in Tables XX, YY, and ZZ below.
Secchi depths were similar between reference sites 1 and 2 and ZID boundary sites 3 and 4, with minimum
secchi depths of 1 foot observed in August 2021. The average of reference sites 1 and 2 was 4.9 feet, while the
average for the ZID boundary sites was 4, approximately 18% lower.
Table 3: SECCHI DEPTH MONITORING
SECCHI (FT)
2016
2017
2018
2019
2020
2021
Ave
Max
Min
Aug
Aug
Aug
Aug
Aug
Aug
Stations
1
2.5
5
4.5
5
6
1
4
6
1
2
11
4
6
5
6
3
5.8
11
3
3
6.6
3
5
2.5
6
1
4
6.6
1
4
6
3.5
5
2.5
5.5
1
3.9
6
1
Average receiving water turbidity values at reference sites 1 and 2 were 12.8, 4.7, and 4.9 NTU for surface,
mid, and bottom depths respectively. Average values within ZID sites 3 and 4 were 19, 6.1, and 4.9 NTU for
surface, mid, and bottom depths respectively. The maximum NTU values of 68.2 and 46.5 were observed in
the surface samples collected at the ZID boundary and reference sites during the August 2021 sampling event,
respectively, the same month of minimum secchi observations.
-------
301(h) Tentative Decision: AK0021466
Table 4: ZID BOUNDARY TURBIDITY MONITORING
Year
Site
Surface
Mid
Bottom
2016
S
te 3
7.83
2.85
1.61
S
te 4
7.72
1.1
1.22
2017
S
te 3
4.59
1.7
3.43
S
te 4
4.68
1.98
3.05
2018
S
te 3
8.82
1.7
2.32
S
te 4
8.25
1.74
2.39
2019
S
te 3
14.3
9.26
8.72
S
te 4
17.8
9.35
9.49
2020
S
te 3
7.91
16.1
7.27
S
te 4
10.2
13.8
8.9
2021
S
te 3
68.2
7.2
5.03
S
te 4
67.7
6.98
4.96
Max
68.2
16.1
9.5
Min
4.6
1.1
1.2
Average
19.0
6.1
4.9
Table 5: TABLE XX: REFERENCE SITE TURBIDITY MONITORING
Year
Site
Surface
Mid
Bottom
2016
S
te 1
14.6
4.06
3.65
S
te 2
6.02
1.3
1.44
2017
S
te 1
2.29
3.06
2.89
S
te 2
4.42
2.19
2.75
2018
S
te 1
8.05
1.92
1.34
S
te 2
10.6
2.43
2.63
2019
S
te 1
6.53
3.54
3.19
S
te 2
9.76
3.56
2.51
2020
S
te 1
23.5
18.3
20.1
S
te 2
6.74
6.03
7.3
2021
S
te 1
46.5
5.77
4.73
S
te 2
14.7
3.67
6.03
Max
--
46.5
18.3
20.1
Min
--
2.3
1.3
1.3
Average
--
12.8
4.7
4.9
EPA considers the low secchi readings and maximum reported surface NTU values to be the result of natural
turbidity from the Stikine River and its significant loading of suspended sediment into the estuarine receiving
waters of Zimovia Straight, not the result of the effluent discharge. Publicly available satellite imagery of the
receiving waters off the west side of Wrangell Island clearly shows the large influence of suspended sediment
originating from the Stikine River to the north. The available receiving water data also supports this
-------
301(h) Tentative Decision: AK0021466
conclusion, with the clear presence of a lower salinity freshwater layer high in suspended sediment over the
top of a higher salinity layer low in suspended sediment. Further, the dilution analysis performed for the
WWTP discharge indicates the effluent plume becomes trapped at a depth of approximately 24 meters (~80
feet), thus preventing the discharge from traveling up through the water column and influencing suspended
solids concentrations near the surface. This strongly indicates that any difference in Secchi depths observed
between sites is the result of local ambient conditions and their results need to be interpreted with caution.
The change in suspended solids in the water column is indirectly related to turbidity measurements. To further
assess the potential for the discharge to cause or contribute to a violation of Alaska WQS for turbidity and light
transmittance, EPA determined the maximum change in suspended solids concentration of TSS in the
discharge at the edge of the ZID using formula B-32 from the 301(h) TSD. The results show a 0.40 mg/L
increase in suspended solids in the receiving water after initial dilution, or 0.8%.
As discussed in the 301(h) TSD, an increase in TSS of less than 10% after initial dilution is not expected to have
a substantial impact on water quality.
Based on the above analyses, the proposed discharge is expected to comply with AK WQS for turbidity and
light transmittance/attenuation. transmittance. See Appendix E for the full equations.
2. Dissolved Oxygen
The effect of the effluent on ambient DO can occur in the nearshore and farfield as effluent mixes with the
receiving water and the oxygen demand of the effluent BOD', load is exerted. Pursuant to 40 CFR 125.61(b)(1)
and 125.62(a)(1), the applicant must demonstrate that the proposed discharge will comply with water quality
criteria for DO and that the outfall and diffuser are located and designed to provide adequate initial dilution,
dispersion, and transport of wastewater such that the discharge does not exceed criteria at and beyond the
ZID. Alaska WQS for DO applicable to the estuarine waters of Zimovia Strait provide that DO may not be less
than 5.0 mg/L except where natural conditions cause this value to be depressed, and in no case may DO levels
exceed 17 mg/L [18 AAC 70.15(a)(i)]. Alaska WQS for DO are shown in in Appendix D.
In accordance with EPA's Amended Section 301(h) Technical Support Document (301(h) TSD), EPA assessed
attainment of the water quality criteria for DO based on review of effluent (2016-2021) and receiving water
monitoring data (2016-2021).
The 301(h) TSD (USEPA 1994) provides several procedures for assessing whether a proposed discharge will
meet water quality criteria for DO at the edge of the ZID. These include calculating the final DO concentration
of the effluent at the edge of the ZID using discharge and receiving water data and assessing the accumulation
of suspended solids around the outfall.
DO Concentration at the Edge of the ZID
EPA calculated the DO concentration at the ZID boundary using receiving water data provided by the applicant
and the procedures described in Equation B-5 of the 301(h) TSD.
The discharge results in a maximum near field DO depletion at the ZID boundary of 0.06 mg/L, or a 0.7%
reduction from ambient concentrations. The minimum DO concentration of the receiving water immediately
following initial dilution is between 4.68 and 7.95 and varies by water depth (surface, mid, or bottom) and
location (reference or outfall). Receiving water sampling data indicates the low DO measurements are the
-------
301(h) Tentative Decision: AK0021466
result of natural conditions within the receiving water. For example, the lowest DO readings occur at the
bottom of the water column at the reference sites, which are located approximately 1000 feet from the ZID
and outside the influence of the discharge. Further, a 0.7% DO reduction at the completion of initial dilution
would be very unlikely to result in the low DO measurements observed at the reference sites 1000 feet away.
Far Field DO Impacts
To assess the potential for far field impacts to DO the final BODs concentration after initial mixing was
determined using the simplified procedures described in Appendix B of the 301(h) TSD and outlined in
Appendix E of this 301(h) TDD. The calculation resulted in a final BOD5 concentration of 1.3 mg/L after initial
mixing, a concentration that is not anticipated to cause or contribute to any measurable far field DO impacts
beyond the ZID.
Suspended Solids Accumulation
Impacts to DO concentrations resulting from the discharge of wastewater can also be assessed by examining
the accumulation of suspended solids. 40 CFR 125.62 states that wastewater and particulates must be
adequately dispersed following initial dilution so as not to adversely affect water use areas. The accumulation
of suspended solids may lower DO in near-bottom waters and cause changes in the benthic communities.
Accumulation of suspended solids in the vicinity of a discharge is influenced by the amount of solids
discharged, the settling velocity distribution of the particles in the discharge, the plume height-of-rise, and
current velocities. Hence, sedimentation of suspended solids is generally of little concern for small discharges
into well-flushed receiving waters.
The questionnaire submitted by the applicant in 2006 states there are no known water quality issues
associated with the accumulation of suspended solids from the discharge.
To evaluate the potential impact of solids sedimentation, a simplified approach for small dischargers that are
not likely to have sediment accumulation related problems can be found in Figure B-2 of the 301(h) TSD. To
use Figure B-2 of the 301(h) TSD to evaluate whether steady state solids accumulation will result in sufficient
sediment accumulation to cause a 0.2 mg/L oxygen depression, the TSS mass emissions rate is needed, as well
as plume height-of-rise. The mass emission or loading rate was calculated using the TSS concentration limit,
facility design flow, and a conversion factor (Loading (lbs/day)) = 45 mg/L X 0.6 mgd X 8.34=225 lbs/day, or
102 kg/day). Plume height-of-rise was calculated to be 60 feet (18.2 meters), using the approach on page B-5
in the 301(h) TSD, which involves multiplying the water depth at the point of discharge (100 feet at MLLW) by
0.6. When a height-of-rise of 18.2 meters and a loading rate of 102 kg/day are input in Figure B-2, steady state
accumulation is well below the line at which greater than 0.2 mg/L oxygen depression is expected. Per the
301(h) TSD, no further analysis is needed to demonstrate that accumulating solids will not result in
unacceptable DO depressions.
Based on the above analyses of DO depletion and suspended solids accumulation, the proposed discharge is
expected to comply with AK WQS for dissolved oxygen. For the complete equations used in this analysis refer
to Appendix E.
-------
301(h) Tentative Decision: AK0021466
C. Attainment of Other Water Quality Standards and Impact Of the Discharge On Shellfish, Fish
And Wildlife; Public Water Supplies; And Recreation
[CWA Section 301(h)(2); 40 CFR 125.62]
CWA Section 301(h)(2) requires that the proposed discharge not interfere, either alone or in combination with
other sources, with the attainment or maintenance of that water quality which assures protection of public
water supplies and protection and propagation of a balanced, indigenous population of shellfish, fish, and
wildlife, and allows recreational activities in and on the water. Pursuant to 40 CFR 125.62(a), the applicant's
outfall and diffuser must be located and designed to provide adequate initial dilution, dispersion, and
transport of wastewater such that the discharge does not exceed, at and beyond the ZID, all applicable EPA-
approved state WQS and, where no such standards exist, EPA's CWA Section 304(a)(1) aquatic life criteria for
acute and chronic toxicity and human health criteria for carcinogens and noncarcinogens, after initial mixing in
the waters surrounding or adjacent to the outfall. In addition, 40 CFR 125.59(b)(1) prohibits issuance of a
301(h)-modified permit that would not assure compliance with all applicable NPDES requirements of 40 CFR
Part 122; under these requirements a permit must ensure compliance with all water quality standards.
Attainment of water quality criteria for DO and turbidity was previously discussed. However, in accordance
with 40 CFR 125.62(a), the applicant must also demonstrate that the proposed discharge will attain other
WQSs, including those for pH, temperature, toxic pollutants, and bacteria. EPA used Alaska WQS, the
processes described in the 301(h) TSD and the 1991 Technical Support Document for Water Quality-based
Toxics Control, and dilution factors of 3.9:1 (acute criteria) and 29:1 (chronic criteria) to determine whether
the proposed discharge has the reasonable potential to cause or contribute to an excursion above AK WQS, to
calculate WQBELs, and to assess compliance with CWA Section 301(h)(2) and 40 CFR § 125.62. To determine
reasonable potential, EPA compares the maximum projected receiving water concentration after mixing to the
water quality criterion for that pollutant. If the projected receiving water concentration exceeds the criterion,
there is reasonable potential for that pollutant to cause or contribute to an excursion above AK WQS, and a
WQBEL must be included in the permit. If a permittee is unable to meet their WQBEL it would fail to satisfy
CWA Section 301(h)(9) and 40 CFR 125.62 and would be ineligible for a CWA Section 301(h) modification.
Pursuant to 40 CFR 125.62(a)(l)(iv), EPA's evaluation of compliance with WQSs must be based upon
conditions reflecting periods of maximum stratification and during other periods when discharge
characteristics, water quality, biological seasons, or oceanographic conditions indicate more critical situations
may exist, commonly referred to as critical conditions.
1. pH
The applicant did not request a CWA Section 301(h) modification for pH, but the proposed discharge must still
meet the WQS for pH. Alaska's WQSs provide that pH may not be less than 6.5 or greater than 8.5 and may
not vary more than 0.2 pH unit outside of the naturally occurring range.
The effect of pH on the receiving water following initial dilution was estimated using Table 1. Estimated pH
Values After Initial Dilution in the 301(h) TSD.
EPA reviewed DMR data for pH between 2016 and 2021. The facility met the pH limits in the 2002 permit
100% of the time. The maximum, minimum, and average pH values observed were 7.8, 6.5, and 7.3 s.u.,
respectively. By utilizing the minimum measured effluent pH value of 6.5, an effluent alkalinity of 0.5 mq/L
(suggested as reasonable for primary effluents with no industrial component on pg 65, 301(h) TSD), a
-------
301(h) Tentative Decision: AK0021466
seawater temperature of 15°C (95th percentile of trapping depth temperature was 13.7° C), and an assumed
initial dilution of 100 (actual initial dilution is 112), the expected resulting pH range after initial dilution is 6.99
to 8.49 over an assumed seawater pH range of 7.00 to 8.50. This is within the range of 6.5 to 8.5 and meets
Alaska WQS for pH.
The proposed discharge is expected to comply with Alaska WQS for pH after iniitial mixing at the edge of the
ZID.
2. Temperature
Alaska's most stringent WQS for water temperature provides that the discharge may not cause the weekly
average temperature to increase more than 1 degree C. The maximum rate of change may not exceed 0.5
degree C per hour. Normal daily temperature cycles may not be altered in amplitude or frequency.
The maximum ocean temperature recorded at the trapping depth of the discharge during receiving water
monitoring from 2016 to 2021 was 13.7°C, and the maximum recorded effluent temperature between 2016
and 2021 was 18.6°C. EPA conducted a mass balance analysis using these values and calculated a final
receiving water temperature of 13.7 after initial dilution. Based upon the above analysis the proposed
discharge is expected to comply with Alaska WQS for temperature at the edge of the ZID.
3. Toxics
Alaska WQS for toxics for marine uses can be found in 18 AAC 70.020(b)(23) and the Alaska Water Quality Criteria
Manual for Toxics (ADEC, 2008).
To assess whether the proposed discharge will comply with Alaska WQS for toxics after initial mixing EPA reviewed
DMR data collected between 2016 and 2021 and the results of three priority pollutant scans performed on the
effluent on March 21, March 28, and April 5, 2006.
Several metals were reported above their respective detection limits. Using this data along with DMR data for
ammonia, EPA performed reasonable potential analyses using the numeric criteria in the Alaska Water Quality
Criteria Manual (ADEC 2008) and the processes outlined in the Technical Support Document for Water Quality-
based Toxics Control (USEPA 1991).
Chlorine and ammonia are the only pollutants with the reasonable potential to cause or contribute to a
violation of Alaska WQS after mixing. WQBELs have been developed and included in the draft permit for
chlorine and ammonia.
The effluent limits for chlorine and ammonia are protective of Alaska WQS.
4. Bacteria
Alaska's WQS for bacteria are found at 18 AAC 17.020(b)(14).
I. Fecal Coliform
Alaska's most restrictive marine criterion for fecal coliform bacteria concentrations is in areas protected for
the harvesting and use of raw mollusks and other aquatic life. The criterion specifies that the geometric mean
of samples shall not exceed 14 MPN/100 mL, and that not more than 10 percent of the samples shall exceed
43 MPN/100 mL. Because Zimovia Straight is protected for this use, this standard must be met at the edge of
the ZID.
-------
301(h) Tentative Decision: AK0021466
On August 2, 2001, ADEC provided a CWA Section 401 Certificate of Reasonable Assurance (401 certification)
that included a mixing zone defined as an arc of a circle with a 1600-meter radius, centered on the outfall
going from one shoreline to the other extending on either side of the outfall line, and extending from the
marine bottom to the surface. ADEC also required in the preliminary certification that fecal coliform limits not
exceed 200 FC/100 mL at the shoreline within the designated mixing zone, except in "Area A," a known
community shellfish gathering area, where 14 FC/lOOmL as a monthly average and 43 FC/lOOmL as a daily
max were to be met. The number of fecal coliform bacteria in the primary treated effluent was not to exceed a
30-day average of 1.0 million FC per 100 mL and a daily limit of 1.5 million FC per 100 mL of sample. Outside
this mixing zone the fecal coliform concentrations were not to exceed a maximum of 14 FC/100 mL for a
monthly average and 43 FC/100 mL for a daily maximum. Facility DMR data from the past 5 years shows fecal
coliform values ranges from 72—60,000 FC/lOOmL, with a 95th percentile of 48,300 FC/lOOmL and a geometric
mean of 7910 FC/lOOmL. Summary statistics of DMR data are provided in Table X below.
Table 6: Fecal Coliform DMR Summary Data 2016-2021
# of
samples
Min
Max
95th
Percentile
Average
Geomean
Fecal Coliform (FC/lOOmL)
68
72
60,000
48,300
14,893
7410
The 2002 permit required the facility to conduct fecal coliform sampling at four receiving water locations
during April, June, August, and November, and at six intertidal locations monthly from May through August for
the life of the permit. The results are presented in Table X below.
Table 7: Fecal Coliform Statistics by Station (2016-2021)
# of samples
Max (FC/lOOmL)
Average (FC/lOOmL)
Geomean (FC/lOOmL)
Station 1
35
280.0
14.7
13.7
Station 2
35
30.0
3.7
15.11
Station 3
35
55.0
6.9
10.7
Station 4
35
50.0
4.0
9.1
Station 5
35
26.0
3.0
7.6
Station 6
35
36.7
1.8
5.7
Station 7
35
10.0
1.0
6.6
Station 8
35
20.0
1.1
10.0
Station 9
35
10.0
0.9
5.0
Station 10
35
25.0
2.2
8.6
Station 11
35
20
1.7
7.8
Area A
35
13.3
5
7
^PA used the maximum geometric mean of the available data as the background concentration (Cu)
in the reasonable potential analysis and effluent limit calculations
Station 1: 1.5 meters from shore along centerline of diffuser, at the head of Cemetary Point
Station 2: 91 meters north of Site 1
Station 3: 91 meters south of Site 1
Station 4: south of Site 1, where 1600-meter mixing zone intersects shore
Station 5: north of Site 1, where 1600-meter mixing zone intersects shore
Station 6: northwest of the outfall at the 1600-meter mixing zone boundary
Station 7: southeast of the outfall at the 1600-meter mixing zone boundary
-------
301(h) Tentative Decision: AK0021466
Station 8: northwest of the outfall in between the 1600-meter mixing zone and the 100-foot radius ZID
Station 9: southeast of the outfall in between the 1600-meter mixing zone and the 100-foot radius ZID
Station 10: 5 meters northwest of ZID boundary
Station 11: 5 meters southeast of ZID boundary
Area A: outside beach area of Point Shekesi, about 3,500 feet northeast of the outfall
The maximum fecal coliform result of 280 occurred at the intertidal shoreline area closest to the outfall,
Station 1. The highest average and geometric mean results were reported at Stations 1, 2, and 3, the three
intertidal stations closest to the outfall. CWA Section 301(h)(9) requires 301(h) discharges to meet WQS and
federal 304(a) criteria at the edge of the ZID. The current 1600-meter mixing zone for fecal coliform is
inconsistent with the statutory or regulatory definition of a ZID: the region of initial mixing surrounding or
adjacent to the outfall.
Consistent with 301(h)(9) and 40 CFR 125.62, EPA used the 112:1 dilution achieved at the edge of the ZID to
evaluate reasonable potential and assess compliance with CWA Section 301(h)(9) and 40 CFR 125.62. ADEC
will not reauthorize the 1600-meter mixing zone for fecal coliform and the point of compliance for all bacteria
limits is now the edge of the ZID.
Using effluent data from 2016 to 2021 and the same process and equations as those used for toxics, EPA
conducted a reasonable potential analysis and determined fecal coliform has the reasonable potential to
cause or contribute to a violation of Alaska WQS at the point of discharge. EPA calculated WQBELs for bacteria
using Alaska WQS and the ZID dilution. For more information on the effluent limits for fecal coliform refer to
the Fact Sheet.
The effluent limits developed for fecal coliform will meet Alaska criteria at the edge of the ZID and will satisfy
the requirements of 301(h)(9) and 40 CFR 125.63(a).
II. Enterococcus Bacteria
Enterococci bacteria are indicator organisms of harmful pathogens recommended by the EPA to protect
primary contact recreation for marine waters. The EPA Beaches Environmental Assessment and Coastal Health
Act (BEACH Act) requires states and territories with coastal recreation waters to adopt enterococci bacteria
criteria into their WQS. EPA approved Alaska's WQS for enterococcus in 2017. The WQS at 18 AAC
70.020(b)(14)(B) for contact recreation specifies that the enterococci bacteria concentration shall not exceed
35 enterococci CFU/lOOmL, and not more than an 10% of the samples may exceed a concentration of 130
enterococci CFU/lOOmL.
The 2002 permit does not contain effluent limitation for enterococcus bacteria because there was no
applicable enterococcus standard in effect when the permit was issued in December 2001.
40 CFR 122.44(d)(1) requires EPA to account for existing controls on discharges when determining whether a
discharge has the reasonable potential to cause or contribute to an excursion of state WQS. The WWTP does
not currently disinfect its effluent, resulting in the high bacterial loads observed in the available fecal coliform
data. The 2002 permit did not require enterococcus monitoring, but it reasons that the high fecal coliform
loads observed are also indicative of high loads of other pathogens commonly found in WWTP effluents,
including enterococcus. With the available fecal coliform data and lack of disinfection capacity at the facility,
EPA has determined there is reasonable potential for the discharge to cause or contribute to a violation of
-------
301(h) Tentative Decision: AK0021466
Alaska WQS for enterococcus. EPA calculated WQBELs using Alaska WQS and the ZID dilution. For more
information on the effluent limits for enterococcus refer to the Fact Sheet.
The effluent limits developed for enterococcus will be protective of Alaska WQS; limits will meet criteria at the
edge of the ZID and will satisfy the requirements of 301(h)(9) and 40 CFR 125.63(a).
D. Impact of the Discharge on Public Water Supplies [40 CFR § 125.62(b)]
40 CFR § 125.62(b) requires that the applicant's 301(h)-modified discharge must allow for the attainment or
maintenance of water quality which assures protection of public water supplies and must not interfere with
the use of planned or existing public water supplies. Based on the 2006 Questionnaire submitted by the
applicant, there are no existing or planned public water supply intakes in the vicinity of the discharge, and the
EPA concludes that the applicant's proposed discharge will have no effect on the protection of public water
supplies and will not interfere with the use of planned or existing public water supplies.
E. Biological Impact of Discharge [40 CFR § 125.62(c)]
40 CFR. § 125.62 requires that in addition to complying with applicable WQS, the proposed improved
discharge must allow for the attainment or maintenance of water quality that assures the protection and
propagation of a balanced indigenous population (BIP) of shellfish, fish, and wildlife. A BIP of shellfish, fish, and
wildlife must exist immediately beyond the ZID and in all other areas beyond the ZID that where marine life is
actually or potentially affected by the applicant's discharge.
According to the applicant the discharge will not cause adverse impacts to habitats of limited distribution or
commercial or recreational fisheries. There have been no known cases of mass mortalities offish or
invertebrates, no increased incidence of disease in marine organisms, and no other known cases of adverse
biological impacts. The application materials indicate the discharge does not cause or contribute to significant
biological impacts. The discharge is relatively small in volume and is composed entirely of domestic
wastewater, with limited quantities of toxics, and no industrial users. Acutely toxic conditions are not
expected since the effluent achieves rapid mixing within minutes of discharge, minimizing the potential
exposure area.
The 2002 permit required the facility to conduct biological monitoring, which consisted of a benthic survey
and sediment analysis for total volatile solids (TVS) at the ZID boundary, within the ZID, and at two reference
locations. Based on the results of the TVS analysis of sediment presented in Table XX, it does not appear that
excess organic sediment is accumulating around the outfall as compared to stations at the ZID Boundary and
reference sites. The results of the TVS analysis are presented in Appendix F. Based on visual observations of
the benthic infauna collected in sediment samples, it does not appear that the Wrangell sewer outfall
discharge is causing significant changes in the benthic community structure.
The Biological Monitoring Program from the 2002 permit is being retained in the draft permit.
F. Impact of Discharge on Recreational Activities [40 CFR § 125.62(d)]
Under 40 CFR 125.62(d), the applicant's discharge must allow for the attainment or maintenance of water
quality that allows for recreational activities beyond the zone of initial dilution, including, without limitation,
swimming, diving, boating, fishing, and picnicking, and sports activities along shorelines and beaches. There
-------
301(h) Tentative Decision: AK0021466
must be no Federal, State, or local restrictions on recreational activities within the vicinity of the applicant's
outfall unless such restrictions are routinely imposed around sewage outfalls.
In its 2006 Questionnaire, the applicant stated that no impacts on recreational activities were expected due to
the proposed discharge. Swimming is not common in Zimovia Straight due to the cold-water temperatures and
diving is expected to be rare due to the turbid nature of the receiving water. In its 2006 Questionnaire, the
facility indicated that recreational fishing for salmon and halibut occur in the receiving water as well as
commercial crab fishing. No adverse effects have been reported.
The 2002 permit required signs to be placed on the shoreline near the 1600-meter fecal coliform mixing zone
and the outfall line that state primary treated domestic wastewater is being discharged, mixing zones exist,
and certain activities such as the harvesting of shellfish for raw consumption and bathing should not take
place within the mixing zone. EPA has retained this language in the draft permit.
G. Establishment of Monitoring Programs [CWA § 301(h)(3); 40 CFR §125.63]
Under 40 CFR 125.63, which implements Section 301(h)(3) of the Act, the applicant must have a monitoring
program designed to provide data to evaluate the impact of the proposed discharge on the marine biota,
demonstrate compliance with applicable WQSs, and measure toxic substances in the discharge. The applicant
must demonstrate the capability to implement these programs upon issuance of a 301(h)-modified NPDES
permit. In accordance with 40 CFR 125.63(a)(2), the applicant's monitoring programs are subject to revision as
may be required by EPA.
1. Influent/Effluent Monitoring Program [40 CFR §125.63(d)]
40 CFR. § 125.63(d) requires an effluent monitoring program and the applicant proposes continuation of the
current monitoring program. In addition to the 301(h) specific monitoring requirements, Section 308 of the
CWA and federal regulation 40 CFR 122.44(i) require monitoring in permits to determine compliance with
effluent limitations. Monitoring may also be required to gather effluent and receiving water data to determine
if additional effluent limitations are required and/or to monitor effluent impacts on receiving water quality.
Throughout the previous permit term (and the administratively continued period), the applicant faithfully
submitted effluent monitoring data to the EPA as required by the 2002 permit.
Summary statistics of the effluent data submitted by the permittee between 2016 and 2021 is presented in
Appendix C.
The draft permit retains largely the same effluent and influent monitoring requirements but includes the new
requirement to monitor the effluent for copper. Consistent with 40 CFR 125.66, the draft permit also includes
a new requirement for the permittee to perform an analysis of their effluent for all toxics and pesticides
identified in 40 CFR Part 401.15 twice during the term of the new permit, once during the wet season and
once during the dry season.
2. Receiving Water Quality Monitoring Program [40 CFR §125.63(c)]
40 CFR 125.63(c) requires that the receiving water quality monitoring program must provide data adequate to
evaluate compliance with applicable WQS. The applicant proposes continuation of the current receiving water
monitoring program. As in the case of effluent monitoring, NPDES permits include receiving water monitoring
requirements to allow for compliance assessment, and to determine if additional effluent limitations and/or
-------
301(h) Tentative Decision: AK0021466
monitoring requirements are necessary in future permitting actions. Since the last permit reissuance the
applicant has faithfully submitted results of receiving water monitoring conducted in accordance with the
terms of the 2002 permit.
EPA is retaining most of the receiving water monitoring program from the 2002 permit in the draft permit.
Changes to the receiving water monitoring program include slight adjustments to the ZID boundary
monitoring locations, the addition of enterococcus to the suite of parameters analyzed, the addition of one
monitoring location over the center of the ZID, and the removal of sampling at the edge of the 1600-meter
mixing zone (Stations 6 and 7). Sampling at the edge of the 1600-meter mixing zone is no longer required since
it is not being reauthorized by ADEC.
3. Biological Monitoring Program [40 CFR §125.63(b)]
40 CFR 125.63(b) requires a permittee to implement a biological monitoring program that provides data
adequate to evaluate the impact of the applicant's discharge on the marine biota. Such a program should, at a
minimum, allow for evaluation of any ecosystems impacts; any changes in the amount of organic material in
the seafloor sediment; any changes to benthic communities; and the effectiveness/bases for permit
conditions.
The Biological Monitoring Program in the 2002 permit consisted of a benthic survey and sediment analysis for
total volatile solids (TVS) at the ZID boundary, within the ZID, and at two reference locations.
Based on the results of the TVS analysis of sediment, it does not appear that excess organic sediment is
accumulating around the outfall as compared to stations at the ZID Boundary and reference sites.
Based on visual observations of the benthic infauna collected in sediment samples, it does not appear that the
Wrangell sewer outfall discharge is causing significant changes in the benthic community structure.
The Biological Monitoring Program from the 2002 permit is being retained in the draft permit.
H. Effect of Discharge on Other Point and Nonpoint Sources
[CWA § 301(h)(4); 40 CFR §125.64]
Under 40 CFR §125.64, which implements Section 301(h)(4) of the Act, the applicant's proposed discharge
must not result in the imposition of additional treatment requirements on any other point or nonpoint source.
The applicant reports that the proposed discharge would not place any additional treatment requirements on
point or nonpoint sources. Pursuant to 40 CFR §125.64(b), the applicant is required to submit a determination
signed by the State of Alaska indicating whether the applicant's discharge will result in an additional treatment
pollution control, or other requirement on any other point or nonpoint sources. The State determination must
include a discussion of the basis for its conclusion. EPA cannot take final action on the 301(h)-modified permit
until this determination is received.
I. Urban Area Pretreatment Program
[CWA § 301(h)(6); 40 CFR §125.65]
Under 40 CFR §125.65 dischargers serving a population greater than 50,000 are required to have a
pretreatment program. As previously discussed, the Wrangell WWTP serves a population of approximately
2,100 people so this provisions in not applicable to this analysis.
-------
301(h) Tentative Decision: AK0021466
J. Toxics Control Program [CWA § 301(h)(7); 40 CFR §125.66]
1. Chemical Analysis and Toxic Pollutant Source Identification [40 CFR §§125.66(a) and (b)]
Under 40 §125.66(a) and (b), applicants are required to perform chemical testing for toxic pollutants and
pesticides and identify the source of any parameters detected, respectively.
As previously discussed, the permittee conducted three toxic pollutant scans in 2006, the results of which EPA
used in development of the draft permit. The applicant indicates that absent any industrial users the likely
source of the copper observed in the 2006 toxic scans is copper drinking water piping and fixtures used
throughout the service area. The new permit requires monthly copper monitoring of the effluent.
Pursuant to 40 CFR 125.66, the draft permit requires a updated toxics and pesticides scan and source
identification analysis be submitted at the time of permit reapplication.
2. Industrial Pretreatment Program [40 CFR §125.66(c)]
40 CFR § 125.66(c) requires that applicants that have known or suspected industrial sources of toxic pollutants
shall have an approved pretreatment program in accordance with the requirements of 40 CFR Part 403
(Pretreatment Regulations). This requirement shall not apply to any applicant which has no known or
suspected industrial sources of toxic pollutants or pesticides and so certifies to EPA. In 2022, the permittee
provided an updated certification that there are no known industrial inputs into the treatment system.
Because the facility has certified that there are no known industrial sources of toxic pollutants, under 40 CFR §
125.66(c)(2), the facility is not required to have an approved pretreatment program.
Pursuant to 40 CFR 126.66, the draft permit requires a updated industrial user survey be submitted at the time
of permit reapplication.
3. Nonindustrial Source Control Program [40 CFR §125.66(d)]
40 CFR §125.66(d), which implements Section 301(h)(6) of the Act, requires the applicant to submit a
proposed public education program designed to minimize the entrance of non-industrial toxic pollutants and
pesticides into its POTW. The applicant must also develop and implement additional nonindustrial source
control programs on the earliest possible schedule. The requirement to develop and implement additional
nonindustrial source control programs does not apply to a small Section 301(h) applicant that certifies there
are no known or suspected water quality, sediment accumulation, or biological problems related to toxic
pollutants or pesticides in its discharge.
The applicant provided this certification, as well as documentation that a public education program meeting
the requirements of 40 CFR 125.66(d)(1) has been developed and implemented. The applicant publishes an
annual Household Hazardous Waste bulletin in the newspaper, on a community bulletin board, and online.
The applicant also advertises and hosts an annual collection event at the Wrangell Waste Transfer Station,
where the public is invited to bring in household hazardous wastes for proper disposal. Wrangell has satisfied
the requirements for nonindustrial source control.
K. Effluent Volume and Amount of Pollutants Discharged [40 CFR § 125.67]
Under 40 CFR § 125.67, which implements Section 301(h)(7) of the Act, the applicant's proposed discharge
may not result in any new or substantially increased discharges of the pollutant to which the modification
-------
301(h) Tentative Decision: AK0021466
applies above the discharge specified in the 301(h)-modified permit. The applicant has applied on the basis of
the current discharge and does not propose any new or substantially increased discharges of TSS or BOD5, the
two parameters for which the facility has requested a waiver.
L. COMPLIANCE WITH OTHER APPLICABLE LAWS
[40 CFR § 125.59]
Under 40 CFR 125.59(b)(3), a 301(h)-modified permit may not be issued if such issuance would conflict with
applicable provisions of Alaska, local, or other federal laws or executive orders. As part of the application
renewal, the applicant must demonstrate compliance with all applicable Alaska and federal laws and
regulations, and executive orders which include the Coastal Zone Management Act, Marine Protection
Research and Sanctuaries Act, and the Endangered Species Act.
1. Coastal Zone Management Act
Alaska withdrew from the voluntary National Coastal Zone Management Program on July 1, 2011 (NOAA
2019c); therefore, this requirement is not applicable.
2. Marine Protection, Research, and Sanctuaries Act
Under 40 CFR 125.59(b)(3), no section 301(h) modified permit shall be issued if such issuance would conflict
with Title III of the Marine Protection, Research, and Sanctuaries Act, 16 USC § 1431 etseq., authorizes the
Secretary of Commerce (i.e., NOAA) to designate and protect areas of the marine environment with special
national significance due to their conservation, recreational, ecological, historical, scientific, cultural,
archeological, educational or esthetic qualities as national marine sanctuaries. In the U.S., there are 14
national marine sanctuaries and 2 marine national monuments, none of which are in Alaska (NOAA 2019d).
The draft permit is therefore expected to comply with Title III of the Marine Protection, Research, and
Sanctuaries Act.
3. Endangered or Threatened Species
Under 40 CFR 125.59(b)(3), no section 301(h) modified permit shall be issued if such issuance would conflict
with the Endangered Species Act (ESA), 16 USC 1531 et seq. The ESA requires federal agencies to consult with
the National Marine Fisheries Service (NMFS) and the U.S. Fish and Wildlife Service (USFWS), or "the Services"
if their actions could beneficially or adversely affect any threatened or endangered species (ESA-listed species)
or designated critical habitat.
EPA has prepared a biological evaluation that identified the following species and/or critical habitat in the
vicinity of the discharge using the following web-based applications. All lists will be verified with the Services.
• NOAA's Alaska Protected Resource Division Species Distribution Mapper:
(https://alaskafisheries.noaa.gov/portal/apps/webappviewer/index.html?id=0c4a81f75310491d9010c
Sc081c81)
o Western Distinct Population Segment (Western DPS or WDPS) Steller sea lions, and
o Mexico DPS humpback whales
• USFWS' Information for Planning and Consultation (IPaC): https://ecos.fws.eov/ipac/
o None
-------
301(h) Tentative Decision: AK0021466
EPA has determined the draft permit may have an effect on these ESA-listed species and/or their critical
habitats and, pursuant to Section 7 of the ESA, will consult with the Services prior to taking final action.
4. Essential Fish Habitat
Under 40 CFR 125.59(b)(3), no section 301(h) modified permit shall be issued if such issuance would conflict
with the Magnuson-Stevens Fishery Conservation and Management Act (MSFCMA), 16 USC 1801 etseq., which
protects against adverse impacts to Essential Fish Habitat (EFH).The MSFCMA requires federal agencies to consult
with the National Marine Fisheries Service (NMFS) when any activity proposed to be permitted, funded, or
undertaken by a federal agency may have an adverse effect on designated Essential Fish Habitat (EFH) as defined
by the Act. The EFH regulations define an adverse effect as any impact which reduces quality and/or quantity of
EFH and may include direct (e.g. contamination or physical disruption), indirect (e.g. loss of prey, reduction in
species' fecundity), site-specific, or habitat-wide impacts, including individual, cumulative, or synergistic
consequences of actions.
EPA will prepare an EFH assessment to assess the impacts of the discharge on EFH. If the EFH assessment concludes
there will be adverse impacts EPA will consult with the NMFS prior to final permit action.
M. STATE DETERMINATION AND CONCURRENCE
[40 CFR § 125.61(b)(2); 40 CFR § 125.64(d)]
Under 40 CFR 125.61(b)(2) the applicant must provide a determination signed by the state or interstate
agency(s) authorized to provide certification under 40 CFR 124.53 and 124.54 that the proposed discharge will
comply with applicable provisions of state law, including WQS. This determination must include a discussion of
the basis for the conclusion reached. Furthermore, pursuant to 40 CFR 124.53 and 124.54, the state must either
grant a certification pursuant to Section 401 of the CWA or waive this certification before EPA may issue a 301(h)-
modified permit. The applicant did not provide this certification at the time of application; EPA will request
401-certification and a determination under 40 CFR § 125.61(b)(2) from ADEC during the public notice period
of the draft permit.
40 CFR 125.64(d) requires applicants to provide a determination from the state or interstate agency(s) having
authority to establish wasteload allocations indicating whether the applicant's discharge will result in an
additional treatment pollution control, or other requirement on any other point or nonpoint sources. The
state determination shall include a discussion of the basis for its conclusion. The applicant did not submit this
determination with their application; EPA will request that this determination be included in ADEC's 401-
certification of the permit.
-------
301(h) Tentative Decision: AK0021466
9) References
ADEC. 2003.18 AAC 70, Water Quality Standards, As Amended Through June 26, 2003. Approved by the EPA in
2004. Available at: https://www.epa.eov/was-tech/water-auality-standards-reeulations-alaska.
ADEC. 2008. Alaska Water Quality Criteria Manual for Toxic and other Deleterious Organic and Inorganic
Substances. Available at: https://www.epa.eov/sites/default/files/2014-12/documents/ak~toxics-manual.pdf
USEPA. 1991. Technical Support Document for Water Quality-based Toxics Control. EPA/505/2-90-001.
USEPA. 1994. Amended Section 301(h) Technical Support Document. EPA-842-B-94-007.
NOAA. 2019a. High and Low Water Predictions West Coast of North and South America Including the Hawaiian
Islands. Retrieved at https://tidesandcurrents.noaa.eov/tk rtml
NOAA. 2019b. Tidal Current Tables 2020 Pacific Coast of North America and Asia. Retrieved at
https://tidesandcurrents.noaa.eov/historic tide ta
NOAA. 2019c. Coastal Zone Management Programs. Web. ttps://coast. * m/mystate/.
NOAA. 2019d. National Marine Sanctuaries. Web. loaa.gow,.
USGS. 2019. National Water Information System. USGS 15024800 Stikine R NR Wrangell AK. Retrieved at
https://waterdata.uses.eov/nwis/inventor -->=15024800.
USGS. 2022. USGS Surface-Water Daily Statistics for the Nation. USGS 15024800 STIKINE R NR WRANGELL AK.
Parameter 80154, Suspended Sediment. 1981-1983.
-------
-------
UD
ID
*—5
(N
O
O
<
-------
301(h) Tentative Decision; AK0021466
B, Outfall Location and Receiving Water Monitoring Maps
Northwestern
Passages
Canada
Hudson Bay
United States
Petersburg
Kupreanof
Island
Mitkof Island
Kuiu Island
Zarembo
Island
Port Protection
Port Alexander
Kosciusko
island.
Coffman Cove
Naukati
-------
301(h) Tentative Decision; AK0021466
FIGURE 6
OUTFALL / DIFFUSFR PLAN A. PROF11 F
ctata.
-------
301(h) Tentative Decision; AK0021466
The location of the outfall pipe on NOAA
Nautical Chart 17384 (Wrangell Harbor and
Approaches) was reported as inaccurate by the
permittee. The outfall line shown in green was
provided and confirmed by the permittee. The
angle of the outfall pipe and sampling site
coordinates were mapped using information
from the permittee and the shoreline mapped in
NOAA Nautical Chart 17334.
Location
Diffuser Midpoint
N Midpoint ZID
E Midpoint ZID
S Midpoint ZID
W Midpoint ZID
Site 1
Site 2
Site 3
Site 4
Site 5
Long
•132.391262
•132.39131
-132.390164
-132.391214
-132.39234
-132.386187
-132.386458
-132.3862
-132.385079
-132.383446
56.453298
56.453571
56.453356
56.453026
56.45324
56.453246
56.454053
56.455983
56.4527
56.450968
. \ Costing
\ \p/ers
® Sampling Locations
Diffuser
Pipeline Path
f J Zone of Initial Dilution
Legend
nrssss- Rgure 1. Receiving Water Sampling
iprr Locations. Qty of WrangeJI °. °.M °°5 °°8 °:1 M4es
——'— Wastewater Treatment Plant. NPDES ,—
Permit No. AK0021466.
Figure 1
-------
301(h) Tentative Decision; AK0021466
The location of the outfall pipe on NOAA
Nautical Chart 17384 (Wrangell Harbor and
Approaches) was reported as inaccurate by the
permittee. The outfall line shown in green was
provided and confirmed by the permittee. The
angle of the outfall pipe and sampling site
coordinates were mapped using information
from the permittee and the shoreline mapped in
NOAA Nautical Chart 17334.
Location
Long
Lat
Diffuser Midpoint
-132.391262
56.453298
N Midpoint ZID
-132.39131
56.453571
E Midpoiftt ZID
-132.390184
56.453356
S Midpoint ZID
-132.391214
56.453026
W Midpoint ZID
-132.39234
56.45324
Site 1
-132.386187
56.453246
Sw2
-132.386458
56.454053
Site 3
-132.3862
56.455983
Site 4
-132.385079
56.4527
Ste 5
-132.383446
56.450968
SpecWl Site A
-132.386036
56.462827
N Reference Ste
-132.401554
56.459212
S Reference Ste
-132.401941
56.447599
U \ \ \ N1 \ \
Legend
© Sampling Locations \
Diffuser s
Pipeline Path
r J Zone of Initial Dik-fon .
\ ¦ s
^9ure 2. Receiving Water Sampling
Locations. Qty of Wrangell ° °;1 o^Miies
sr=.c:.tsrss-— Wastewater Treatment Plant NPDES
Permit No. AK0021466.
60
t
N Reference
6? V /*
/ / •/.
\ I
\ /
ajuvAA/HUVVVVV
J . ' 44
I o \
J*
S CO ' I
V• \ ** \
/< 44
\ % > J i
* % \
i -
\ \
I t
•i5 Reference
Site @
I \
Figure 2
-------
301(h) Tentative Decision: AK0021466
C. Summary Statistics of Discharge Monitoring Data (2016-2021)
1 5th Percentile
I 95th Percentile
I 99th Percntile
o
<
1 Std Dev 1
I Count
I Minimum
I Maximum
08/31/2021 I
I 07/31/2021 I
06/30/2021
05/31/2021 I
04/30/2021 I
03/31/2021 I
02/28/2021 I
01/31/2021 I
I 12/31/2020 I
11/30/2020
10/31/2020 I
09/30/2020 I
08/31/2020 I
07/31/2020 I
I 06/30/2020 I
I 05/31/2020 I
I 04/30/2020 I
| 03/31/2020 |
I 02/29/2020 I
01/31/2020
12/31/2019 I
I 11/30/2019 I
I 10/31/2019 I
I 09/30/2019 I
08/31/2019
07/31/2019 I
I 06/30/2019 I
5/1/2019 I
4/1/2019 I
3/1/2019 I
2/1/2019 I
1/1/2019 I
12/1/2018 I
11/1/2018 I
I 10/1/2018 I
I 9/1/2018 I
8/1/2018
7/1/2018 I
6/1/2018 I
I 5/1/2018 I
4/1/2018
3/1/2018 I
2/1/2018 I
1/1/2018 I
I 12/1/2017 I
1 11/1/2017 I
10/1/2017
9/1/2017 I
8/1/2017 I
7/1/2017 I
6/1/2017 I
5/1/2017 I
4/1/2017 I
3/1/2017 I
2/1/2017 I
1/1/2017 I
12/1/2016 I
11/1/2016 I
10/1/2016 I
I 9/1/2016 I
8/1/2016
I 7/1/2016 I
6/1/2016
5/1/2016 I
4/1/2016 I
I 3/1/2016 I
2/1/2016
I 1/1/2016 I
I Effluent Limitation
Statistical Basis
Parameter
1 37.45 1
I 185.50 I
I 226.60 I
p
1 46.71 I
I 68.00 I
I 32.00 I
I 240.00 I
a
a
g
a
S
3
3
o
s
ro
¦P»
i
§
¦P»
CO
¦P»
CO
s
2
s
2
S
M
i
£
s
S
g
g
§
$
g
a
CD
2
g
2
g
2
a
a
a
a
s
¦p*
2
g
g
2
¦p*
CD
S
a
a
a
8
2
8
2
z
>
INFLUENT
03
O
D
3
[Q g
C Q.
in
o
a
1
ro
&
ro
¦P>.
a
r 68.00 I
| oo oou J
a
K
CO
¦p>.
£
s
5
s
CO
K
3
s
a
g
8
£
s
6J
s
¦p*
-
s
=
£
a
2
£
¦p*
5
2
5
CO
s
-
a
¦p*
CD
ro
s
s
s
s
£
u
s
1
DAILY MAX
03
O
o
Q S
£ Q.
in
o
a
1
ro
&
ro
a
r 68.00 I
00 00I-.,
a
K
CO
CO
s
5
s
S
s
a
g
8
£
s
6J
s
-
s
a
2
5
2
5
s
-
a
-
CO
CO
ro
s
s
s
CO
s
CD
u
s
a
9AV0IA1
r 22.60 |
CO
ro
CO
£
r 68.00 I
r 17.35 I
s
S
I 36.73 I
O
CO
I 38.75
I 32.03
I 29.21
I 57.42
CO
£
I 27.01
I 30.69
1 46.33
I 51.34
I 79.34 I
I 47.13 I
I 26.72 I
I 41.31 |
¦p»
^1
41.06
CO
I 296.7 I
p
I 100.98 I
39.44
I 43.57
"
I 25.07
I 27.92
I 40.16
I 30.03
p
I 26.53
I 26.37 I
I 56.08 I
S
41.21
17.35
I 38.26 I
34.17
46.01
41.18
I 48.12 I
I 29.89 I
s
I 35.01
1 62.14
I 42.04
I 31.51
I 50.79
I 45.45
I 33.75
CO
¦P»
CO
CO
I 24.36
2
27.82
t
ro
¦P»
2
£
1 1001 I
DAILY MX
BOD5 20 deg. C
(lbs/day)
09*33 „
CO
1
CO
£
r 68.00 I
r 17.35 I
s
S
36.73 I
E
38.75 I
*>¦
32.03 I
57.42 I
CO
£
2
30.69 I
46.33 1
51.34 I
79.34 I
47.13 I
26.72 I
41.31 |
^1
41.06
296.7 I
$
100.98 I
39.44
43.57 I
25.07 I
!3
27.92 I
40.16 I
30.03 I
p
26.53
26.37 I
56.08 I
s
41.21
17.35
38.26 I
5
34.17
46.01
41.18
48.12 I
29.89 I
K
2
62.14
42.04 I
2
50.79 I
45.45 I
33.75 I
CO
24.36 I
2
27.82
t
2
£
2
MOAVG
£
to
r 91.83 I
¦P>.
r 10.56 I
r 68.00 I
£
r 94.17 I
a
I 71.05 I
S
a
I 85.39 I
I 87.27 I
I 74.19 I
I 56.76 I
I 84.93 I
76.56
I 69.38 I
1 82.43 1
I 84.44 I
I 74.55 I
I 82.31 I
I 65.85 I
I 83.13 |
<3i
I 84.09 1
s
S
s
86.67
I 66.67 I
2
CD
94.17
67.31
s
s
3
6978 |
75.79 I
2
I 83.85 I
I 90.67 I
I 78.08 I
2
I LZ'LL I
I 78.26 I
77.36 I
71.05
a
72.97
88.33
81.16
86.43
68.52
ro
I 76.54 I
I 67.35 I
I 85.39 I
%
I 71.79 I
89.09
2
a
3>
ro
5
a
2
a
Min %
Removal
BOD5
(% removal)
1 32.90 I
I 185.50 I
I 239.80 I
ro
I 48.56 I
I 68.00 I
I 27.00 I
I 280.00 I
i
3
s
§
D
s
3
2
o
s
3
8
§
¦P»
s
CD
CD
§
s
3
<3i
s
2
2
s
§
CO
s
s
g
§
a
g
g
s
&
2
a
s
a
s
s
a
a
g
a
£
g
CO
a
§
S
§
S3
a
s
g
Z
£
INFLUENT
TSS (mg/L)
r 24.10 I
S
ro
ro
¦P>.
CO
r 68.00 I
r 48.00 I
=
s
5
s
£
5
5
o
B
£
s
£
£
3
£
t*
CO
il
s
8
a
5
£
s
5
ro
£
5
s
5
5
¦p*
CD
=
s
ro
CO
o,
5
5
a
1
DAILY MX
TSS (mg/L)
2
r 24.10 I
S
ro
ro
CO
r 68.00 I
r 48.00 I
=
s
5
s
£
5
5
o
K
£
s
CD
3
£
CO
il
il
il
s
to
a
5
£
s
5
ro
£
5
s
5
5
£
3
s
ro
CO
o,
5
5
a
¦p*
9AV0IA1
r 12.03 I
3
r 81.89 I
CO
r 16.78 I
r 68.00 I
9)
r 99.17 I
I 13.36 I
CO
CO
I 30.44 I
¦P*
CO
I 34.32 I
S
I 57.42 I
I 59.59 I
£
22.74
18.79
16.75
16.87
I 62.34 I
I 32.78 I
I 30.54 I
53.11 |
s
¦P*
CO
CO
34.24
s
I 27.61 I
13.41
s
S)
14.33
5
23.93
40.16
39.27
I 13.18 I
I 29.26 I
73.38
99.17
I 35.87 I
i
27.34
39.44
41.18
I 44.42 I
I 39.85 I
17.68
30.89
40.39
I 33.03 I
I 36.36 I
I 37.43 I
I 34.63 I
I 26.72 I
I 30.44 I
S
I 18.73 I
I 12.68 I
S
37.09
t±
s
I 60.34 I
I 34.63 I
1
£
i
DAILY MX
TSS (lbs/day)
r 12.03 I
s
r 81.89 I
CO
r 16.78 I
r 68.00 I
s
r 99.17 I
I 13.36 I
CO
I 30.44 I
CD
I 34.32 I
I 36.51 I
I 57.42 I
I 59.59 I
e
22.74
18.79
16.75
16.87
I 62.34 I
I 32.78 I
I 30.54 I
I 53.11 |
CO
CO
34.24
s
I 27.61 I
13.41
I 12.91 I
s
I 14.33 I
5
23.93
40.16
39.27
10.61
I 13.18 I
I 29.26 I
*>¦
I 73.38 I
I 99.17 I
I 35.87 I
27.34
39.44
41.18
| 44.42 I
I 39.85 I
17.68
I 30.89 I
I 40.39 I
I 33.03 I
I 36.36 I
I 37.43 I
I 34.63 I
I 26.72 I
I 30.44 I
£
I 18.73 I
I 12.68 I
£
37.09
JO
s
I 60.34 I
I 34.63 I
p
£
9AV0IA1
r 59.04 |
r 95.60 I
r 96.10 I
p
r 12.02 I
r 68.00 I
r 42.00 I
r 96.70 I
CD
CO
I 88.89 I
a
o
80.82
82.95
61.54
48.39
I 76.19 I
SI
s
82.86
93.56
93.48
I 80.36 I
I 86.21 I
I 65.22 I
79.07 |
S
66.07
95.35
g
S
I 78.13 I
95.47
86.67
g
P?
s
95.71
64.58
63.83
sn
D
s
s
I 80.47 I
I 58.26 I
a
£
I 82.35 I
g
I 70.59 I
I 69.23 I
I 73.33 I
70.67
I 84.69 I
I 81.16 I
I 87.64 I
I 80.77 I
3
I 74.07 I
I 76.25 I
I 78.18 I
I 72.73 I
S3
2
I 69.23 I
86.67
3?
3
S
I 74.07 I
a
g
a
Min %
Removal
TSS
(% removal)
r 394.00 |
r48300.00 I
| 00 0998S J
£
3>
o
r 68.00 I
r 72.00 I
| 00 00009 J
7700
I 5400 I
3300
4100
8400
12000
I 5700
I 27000
I 12000 I
35000
1
1
1
58000
I 45000 I
I 4000 I
I 14000 I
3100 |
1 30000 1
2700
2300
I 21000 I
I 60000 I
I 24000 I
23000
§
1
3600
21000
3200
36000
15000
21000
IS
3
I 20000 I
i
I 26000
I 12000
I 23000 I
2000
I 2800
1 23000
I 7500
I 7300 I
I 4600 I
2000
I 20000
I 25000
g
§
I 24000
|
I 30000
I 25000
I 30000
I 51000
I 4100
1
I 2100 I
1
|
g
I 18000
I 44000
I 30000 I
16000
I 12000 I
1 1500000 I
DAILY MX
Fecal coliform, MPN,
44.5 C (#/100mL)
r 394.00 |
§
00 0998S „
£
3>
r 68.00 I
r 72.00 I
00 00009 „
7700
5400 I
3300
4100
8400
12000
5700
27000
12000 I
35000
1
1
1
58000 I
45000 I
4000 I
14000 I
3100 |
30000 1
2700
2300
21000 I
60000 I
24000 I
23000
4500
g
3600
21000
3200 I
36000 I
15000 I
21000 I
1
3
20000 I
1
26000 I
12000 I
23000 I
2000
2800 I
23000 1
7500 I
7300 I
4600 I
2000
20000 I
25000 I
1
4500 I
24000 I
|
30000 I
25000 I
30000 I
51000 I
4100 I
1200 I
2100 I
i
I 0009
g
18000 I
44000 I
30000 I
16000
12000 I
1000000 I
MO GEO
CO
CO
1
&
£
I 68.00 I
1
I 0.494 I
I 0.36394 I
0.604
CO
I 0.619 I
0.84164
0.762
0.7975
£
1
1.176
0.71189
5
I 0.78302 I
I 0.43317 I
I 0.4149 I
I 0.48746 I
I 0.667 |
1 0.762 1
1.034
0.6799
I 0.786 I
I 0.652 I
I 0.56346 I
0.56346
I 0.25781 I
0.575
0.379
I 0.42106 I
I 0.36737 I
I 0.83966 I
I 0.828 I
I 0.58014 I
I 0.855 I
I 0.87436 I
0.658
I 0.75165 I
I 0.335 I
I 0.372 I
p
I 0.488 I
1 0.45522 1
p
p
I 0.515 I
0.579
I 1.352 I
I 1.23953 I
1 0.50068 1
I 0.448 I
I 0.92952 I
1 0.625 1
I 0.533 I
I 0.896 I
I 0.689 I
I 1.26693 I
I 0.79265 I
I 0.584 I
I 0.909 I
0.45523
1 0.45471 I
0.311
I 0.645 I
I 0.822 I
I 0.533 I
0.695
I 0.745 I
£
DAILY MAX
Flow (mgd)
£
ro
s
p
g
I 68.00 I
p
p
I 0.314 I
I 0.243 I
0.281
I 0.315 I
I 0.436 I
s
I 0.434 I
I 0.442 I
0.497
s
s
0.453
0.333
I 0.315 I
I 0.249 I
I 0.287 I
0.321 |
1 0.459 1
0.426
0.412
I 0.559 I
I 0.391 I
I 0.362 I
p
I 0.212 I
1 0.264 1
I 0.234 I
I 0.288 I
I 0.274 I
I 0.298 I
I 0.427 I
I 0.372 I
I 0.351 I
I 0.317 I
0.294
I 0.283 I
I 0.235 I
I 0.273 I
0.286
I 0.355 I
1 0.317 I
I 0.358 I
I 0.375 I
I 0.316 I
0.382
I 0.439 I
I 0.429 I
1 0.374 1
I 0.348 I
I 0.368 I
1 0.317 I
I 0.346 I
I 0.379 I
I 0.408 I
I 0.435 I
I 0.379 I
I 0.282 I
I 0.452 I
p
I 0.292 I
0.247
CO
I 0.343 I
I 0.346 I
0.359
I 0.382 I
S
MOAVG
CO
I 27.20 I
I 27.12 I
t
I 23.00 I
1 28.00 1
a
£
=
2
£
£
s
¦p*
8
5
£
s
s
£
CO
£
DAILY MX
Nitrogen,
ammonia total
£
r 10.22 I
r 10.59 I
p
I 68.00 I
1 10.62 I
s
£
CD
2
s
s
CO
1
s
2
o
Lo
Lo
CD
¦P*
I
S
CO
io
5i
CD
CD
fe
S)
io
§o
5
£
£
s
£
s
CO
t-
^1
Lo
CO
CO
io
CD
£
3
5
ro
CO
ro
D
CO
s
S
I 10.58 I
I 10.62 I
CD
5
CD
CD
8
io
£
=s
lAiniAJIXVIAl
D.O. (mg/L)
o
is
p
S
I 68.00 I
CO
ro
&
S
£
1
¦f*
3>
O)
O)
£
CD
3>
3>
CO
CO
§
k
in
;P>.
CO
->l
¦P»
5
£
CO
ro
3
ro
ro
o,
£
£
CD
g
p»
D
ro
P»
S
&
a
8
*
*
3
8
ro
¦P»
ro
Id
ro
8
S
5
8
S
*
lAlfllAIINIlAI
Ej
5
s
p
=
I 68.00 I
£
CD
s
2
£
s
2
s
a
CD
s
io
Hi
b>
5
2
5
b>
£
*2
2
CO
ro
b
s
5
5
ro
ro
3
a
2
3
s?
ro
s
5
S
2
5
3
2
£
MAX
pH (S.U.)
s
^1
g
I 68.00 I
g
^1
CO
£
s
£
s
s
£
I
£
CO
s
5
5
b:
10
s
3>
s
5
£
5
2
s
s
£
g
ro
5
5
5
£
5
D
ro
p
z
§
1 17.96 I
I 18.48 I
p
I 68.00 I
N
I 18.63 I
16.85
I 17.71 I
s
5
CO
S
£
10.35
£
15.57
16.41
I 13.28 I
2
£
£
S
I 10.23 I
I 14.78 I
17.09
18.63
1 16.05
I 1418
g
s
£
3>
I 10.71 I
I 1406 I
18.12
3)
I 16.04
£
2
ro
L
S
ro
10.43
I 16.47
1 15.87
I 1449
I 12.24
5
CO
CO
8
3
£
I 1476 I
17.63
I 13.13
I 10.71
ro
&
M
1
MOAVG
Temp (C)
-------
301(h) Tentative Decision: AK0021466
D. Alaska WQS
Alaska WQS for Turbidity for Marine Uses
Water Quality Standards for Designated Uses
POLLUTANT & WATER USE
CRITERIA
(24) TURBIDITY, FOR MARINE
WATER USES
(A) Water Supply
(i) aquaculture
May not exceed 25 nephelometric turbidity units
(NTU).
(A) Water Supply
(ii) seafood processing
May not interfere with disinfection.
(A) Water Supply
(iii) industrial
May not cause detrimental effects on established
levels of water supply treatment.
(B) Water Recreation
(i) contact recreation
Same as (24)(A)(i).
(B) Water Recreation
(ii) secondary recreation
Same as (24)(A)(i).
(C) Growth and Propagation of
Fish, Shellfish, Other Aquatic
Life, and Wildlife
May not reduce the depth of the compensation
pointfor photosynthetic activity by more than 10%.
May not reduce the maximum secchi disk depth by
more than 10%.
(D) Harvesting for Consumption
of Raw Mollusks or Other
Raw Aquatic Life
Same as (24)(C).
Alaska WQS for Dissolved Gas for Marine USes
Water Quality Standards for Designated Uses
POLLUTANT & WATER USE
CRITERIA
(15) DISSOLVED GAS, FOR
MARINE WATER USES
(B) Water Supply
(i) aquaculture
Surface dissolved oxygen (D.O.) concentration in
coastal water may not be less than 6.0 mg/l for a
depth of one meter except when natural conditions
cause this value to be depressed. D.O. may not be
reduced below 4 mg/l at any point beneath the
surface. D.O. concentrations in estuaries and tidal
tributaries may not be less than 5.0 mg/l except
where natural conditions cause this value to be
depressed.
In no case may D.O. levels exceed 17 mg/l. The
concentration of total dissolved gas may not
-------
301(h) Tentative Decision: AK0021466
exceed 110% of saturation at any point of sample
collection.
(A) Water Supply
(ii) seafood processing
Not applicable.
(A) Water Supply
(iii) industrial
Not applicable.
(C) Water Recreation
(i) contact recreation
Same as (15)(A)(i).
(B) Water Recreation
(ii) secondary recreation
Same as (15)(A)(i).
(C) Growth and Propagation of
Fish, Shellfish, Other Aquatic
Life, and Wildlife
Same as (15)(A)(i).
(D) Harvesting for Consumption
of Raw Mollusks or Other
Raw Aquatic Life
Same as (15)(A)(i).
Alaska WQS for pH for Marine Uses
Water Quality Standards for Designated Uses
POLLUTANT & WATER USE
CRITERIA
(18) pH, for marine water uses
(variation of pH for waters naturally
outside the specified range must be
toward the range)
(A) Water Supply
(i) Aquaculture
May not be less than 6.5 or greater than 8.5, and may
not vary more than 0.2 pH unit outside of the
naturally occurring range.
(A) Water Supply
(ii) seafood processing
May not be less than 6.0 or greater than 8.5.
(A) Water Supply
(iii) industrial
May not be less than 5.0 or greater than 9.0
(D) Water Recreation
(i) contact recreation
May not be less than 6.0 or greater than 8.5. If the
natural pH condition is outside this range, substances
may not be added that cause any increase in
buffering capacity of the water.
(B) Water Recreation
(ii) secondary recreation
Same as (18)(A)(iii).
-------
301(h) Tentative Decision: AK0021466
(C) Growth and Propagation of
Fish, Shellfish, Other Aquatic
Life, and Wildlife
Same as (18)(A)(i).
(D) Harvesting for Consumption
of Raw Mollusks or Other
Raw Aquatic Life
Same as (18)(A)(ii).
Alaska WQS for Temperature for Marine Uses
Water Quality Standards for Designated Uses
POLLUTANT & WATER USE
CRITERIA
(22) TEMPERATURE, FOR
MARINE WATER USES
(C) Water Supply
(i) aquaculture
May not cause the weekly a\ erage temperature
toincrease more than 1° (' The maximum rate of
change may not exceed 0.5UC per hour. Normal
daily temperature cycles may not he altered
i nam pi i tude or frequency.
(A) Water Supply
(ii) seafood processing
May not exceed 1 5" ('
(A) Water Supply
(iii) industrial
May not exceed 25" C
(E) Water Revival ion
(i) contact recreation
Not applicable
(B) Water Recreation
(ii) secondary ivcivalion
Not applicable
((') (irowill and Propagation of
I'ish. Shellfish. Other
Aquatic
l.ile. and Wildlife
Same as (22)(A)(i).
(D) 1 hi nesting for
Consumptionof Raw
Mollusks or Other
Raw Aquatic 1 .ill-
Same as (22)(A)(i).
Alaska WQS for Toxics for Marine Uses
Water Quality Standards for Designated Uses
POLLUTANT & WATER USE
CRITERIA
(23) TOXIC AND OTHER
DELETERIOUS ORGANIC
AND INORGANIC
SUBSTANCES, FOR MARINE
WATER USES
(D) Water Supply
(i) aquaculture
Same as (23)(C).
-------
301(h) Tentative Decision: AK0021466
(A) Water Supply
(ii) seafood processing
The concentration of substances in water may not
exceed the numeric criteria for aquatic life for marine
water shown in the Alaska Water Quality Criteria
Manual (see note 5). Substances may not be
introduced that cause, or can reasonably be expected
to cause, either singly or in combination, odor, taste,
or other adverse effects on the use.
(A) Water Supply
(iii) industrial
Concentrations of substances that pose hazards to
worker contact may not be present.
(F) Water Recreation
(i) contact recreation
There may be no concentrations of substances in
water, that alone or in combination with other
substances, make the water unfit or unsafe for the
use.
(B) Water Recreation
(ii) secondary recreation
Concentrations of substances that pose hazards to
incidental human contact may not be present.
(C) Growth and Propagation of
Fish, Shellfish, Other Aquatic
Life, and Wildlife
The concentration of substances in water may not
exceed the numeric criteria lor aquatic life for marine
water and human health for consumption of aquatic
organisms only shown in the . \laska Water Quality
("riteria Manual (see note 5), or any chronic and
acute criteria established in this chapter, for a toxic
pollutant of concern, to protect sensitive and
biologically important life stages of resident species of
this state There may be no concentrations of toxic
substances in water or in shoreline or bottom
sediments, that, singly or in combination, cause, or
reasonably can be expected to cause, adverse effects on
aquatic life or produce undesirable or nuisance aquatic
life, except as authorized by this chapter. Substances
may not be present in concentrations that individually
or in combination impart undesirable odor or taste to
fish or other aquatic organisms, as determined by either
bioassay or organoleptic tests.
(l)j 1 lar\ esting lor Consumption
of Raw Mollusks or Other
Raw Aquatic l.ile
Same as (23)(C).
-------
301(h) Tentative Decision: AK0021466
Alaska WQS for Bacteria for Marine Uses
Water Quality Standards for Designated Uses
POLLUTANT & WATER USE
CRITERIA
(14) BACTERIA, FOR MARINE
WATER USES, (see note 1)
(E) Water Supply
(i) aquaculture
For products normally cooked, the geometric mean of
samples taken in a 30-day period may not exceed 200fecal
coliform/100 ml, and not more than 10% of the samples
may exceed 400 fecal coliform/100 ml. For products not
normally cooked, the geometric mean ofsamples taken in a
30-day period may not exceed 20
fecal coliform/100 ml. and not more than 10% of the
samples may exceed 40 fecal coliform/100 ml.
(A) Water Supply
(ii) seafood processing
In a 30-day period, the geomelric mean of samples may
not exceed 2<> leeal coliform 1 <)<> ml. and not more than
10% of the samples may exceed 4<) leeal
coliform Inn ml
(A) Water Supply
(iii) industrial
Where worker contact is present, the geomelrie meanof
samples taken in a 30-dav period may nol exceed 200
fecal coliform/100 ml. and nol more than 10% of
the samples max exceed 4<>t) fecal coliform/100 ml.
(G) Water Recreation
(i) contact recreation
In a 30-dav period, the geomelrie mean of samples may
not exceed 35 enlerococci CM 100 ml, and notmore
than 1')% of die samples ma\ exceed a statistical
threshold \alue (S I V) of 130 enterococci
( 11 1 ill
(B) Water Recreation
(ii) secondary recreation
In a 3
-------
301(h) Tentative Decision: AK0021466
E. Equations and Analysis
1. Part 8.B.1: Attainment of TSS Standard
EPA calculated the maximum change in the concentration of TSS at the edge of the ZID using formula B-32
from the 301(h) TSD. The maximum daily TSS limitation of 45 mg/L and the modeled critical initial dilution of
112:1 were used in the equation. The results show a 0.40 mg/L increase in suspended solids in the receiving
water after initial dilution, or 0.8%.
Formula B-2
SS = SSe/Sa
where,
SS = change in suspended solids concentration following initial dilution
SSe = effluent suspended solids concentration (45 mg/L)
Sa = critical initial dilution (112:1)
45/112 = 0.4 mg/L
2. Part 8.B.2: Attainment of DO Standard
EPA calculated the final concentration of DO at the boundary of the ZID using equation B-5 from the 301(h)
TSD. The analysis is presented in Table X below.
Table X: Dissolved Oxygen Analysis
Dissolved Oxygen in mg/L
Surface
Mid
Bottom
Notes
Ambient DO concentration (DO ) =
(reference sites)
7.95
5.33
4.68
minimum observed
at two reference
sites
Ambient DO concentration (DO ) =
(ZID boundary sites)
8.11
5.61
4.98
minimum observed
at two outfall sites
Effluent DO concentration (DO ) =
3.6
3.6
3.6
5th Percentile
Immediate DO demand (IDOD) =
2.0
2.0
2.0
Table B-3 301(h) TSD1
Initial dilution (Sa) =
112
112
112
Dilution modeling
results
Final DO at Reference Sites
DOf = DOa - (DOa + IDOD - DOe)/Sa =
(using reference site ambient DO)
7.89
5.30
4.65
Equation B-5 from
301(h) TSD, using
reference site
ambient DO
Assuming 0 mg/L effluent (worst-case)
DOf = DOa - (DOa + IDOD - DOe)/Sa =
7.86
5.26
4.62
Worst-Case
FINAL DO at ZID Boundary
DOf = DOa - (DOa + IDOD - DOe)/Sa =
(using ZID boundary ambient DO)
8.05
5.57
4.95
Equation B-5 from
301(h) TSD, using
outfall site ambient
DO
Depletion at Refence Sites
-0.06 (0.7%)
-0.03 (0.6%)
-0.03 (0.6%)
Depletion at ZID Boundary Sites
-0.06 (0.7%)
-0.04 (0.7%)
-0.03 (0.6%)
-------
301(h) Tentative Decision: AK0021466
1 Primary facility, effluent BODs 50-100 mg/L, travel time 0-100 minutes.
The final BOD5 after initial dilution was also calculated to assess the potential for far field DO impacts using a
simplified procedure from Appendix B of the 301(h) TSD. The maximum reported average monthly BOD5 value
is first converted to ultimate BOD5 by multiplying it by the constant 1.46. The ultimate BOD5 is then divided by
the initial dilution factor (112) to determine the final BOD5 after initial dilution.
Max BOD5: 100 mg/L
Ultimate BOD5: 100 mg/L x 1.46= 146 mg/L
Final BOD5: 146 mg/L
= 1.3 mg/L BODs
112
A final BOD5 concentration of 1.3 mg/L after initial dilution is not expected to cause or contribute to any
measurable far field DO impacts.
3. Part 8.C.3. Toxics Analysis
The following mass-balance equation was used to determine whether the discharge has reasonable potential to
cause or contribute to an excursion above Alaska WQS:
Ce + [ Cu ( Sa -1) ]
Cd = where
Sa
Cd = Resultant magnitude or predicted concentration at edge of mixing zone, |ig/L
Ce = Maximum projected effluent concentration, |.ig/L
Cu = Background receiving water concentration, |.ig/L
Sa = dilution factor
The maximum projected effluent concentration (Ce) in the mass balance equation is represented by the highest
reported concentration measured in the effluent multiplied by a reasonable potential multiplier. The reasonable
potential multiplier accounts for uncertainty in the data. The multiplier decreases as the number of data points
increases and variability of the data decreases. Variability is measured by the coefficient of variation (CV) of the
data. When there is not enough data to reliably determine a CV (n<10), the TSD recommends using 0.6 as a default
value. A partial listing of reasonable potential multipliers can be found in Table 3-1 of the TSD. The resulting
maximum projected effluent concentration is then divided by the minimum critical dilution. This product
represents the maximum effluent concentration at the edge of the ZID. The maximum effluent concentration at the
edge of the ZID is then added to the background concentration, Cu, which is represented by the 95th percentile
value from the background data set (the 5th percentile value is used for DO). The sum Cd represents the projected
maximum receiving water concentration at the edge of the ZID. This concentration is compared to the water
quality criterion to determine whether a water-quality based effluent limitation is needed. If the receiving water
concentration at the edge of the ZID exceeds the water-quality criteria a water-quality based effluent limitation is
-------
301(h) Tentative Decision: AK0021466
developed. If a permittee is unable to meet their WQBEL they would fail to satisfy CWA § 301(h)(9) and 40 CFR
125.62 and would be ineligible for a 301(h)-modified permit.
A summary of the reasonable potential analyses is presented in Table X. The Table footnotes indicate the
criterion source used to evaluate reasonable potential (i.e., the criterion in effect for Clean Water Act
purposes). Chlorine is the only constituents that demonstrated reasonable potential. A WQBEL for chlorine
have been developed and included in the draft permit. The effluent limits developed for chlorine are
protective of Alaska WQS, and the proposed discharge is expected to comply with AK WQS for toxics after
initial mixing, satisfying the requirements of CWA § 301(h)(9) and 40 CFR 125.62. For more information on the
process used to develop effluent limits refer to Part IV of the Fact Sheet.
Reasonable Potential Analysis for Toxic Pollutants in the Effluent
Parameter
n
Max
Value
(M-g/L)
TSD
Multiplier
at 95th
Percentile
Max Ce
(M-g/L)
Cu
(me/l)
Sa (dilution
factor)
Cd
(Mg/L)
WQC
(Mg/L)
RP1
(Y/N)
Arsenic
2
1.5
7.4
11.4
0.0
3.9 (acute)
29 (chronic)
0.1
36.02
N
Chlorine3
—
750
4.7
3552.0
0.0
3.9 (acute)
29 (chronic)
317.1
132
Y
Chromium VI
1
1.5
13.2
19.1
0.0
3.9 (acute)
29 (chronic)
1.7
502
N
Copper4
3
51.2
5.6
286.7
1.1
3.9 (acute)
29 (chronic)
3.2
3.12
N4
Lead
3
1.4
5.6
7.8
0.0
3.9 (acute)
29 (chronic)
0.7
8.12
N
Nickel
3
3.7
5.6
20.7
0.7
3.9 (acute)
29 (chronic)
2.5
8.22
N
Silver
1
1.6
13.2
21.1
0.0
3.9 (acute)
29 (chronic)
1.6
1.92
N4
Zinc
2
110.0
3.8
418.0
1.1
3.9 (acute)
29 (chronic)
4.2
81.02
N
Ammonia
23
28,000.0
1.9
53,200.0
0.2
3.9 (acute)
29 (chronic)
471.0
1,200.02,5
N
1. RP based on formula:
Ce+ [Cu (Sa-1) ]
Cd =
Sa
Where:
n= number of samples
Max Value = Max facility-reported effluent concentration in ng/L
TSD X = Multiplier using 95th Percentile, CV of 0.6, and n=2 (except for ammonia, where CV=0.4 and n=211) found in EPA's
Technical Support Document for Water Quality-based Toxics Control (EPA/505/2-90-001, March 1991).
Max Ce = Max effluent concentration X TSD multiplier
Ce = Max effluent concentration
Cu = Background receiving water concentration in ng/L
Sa = dilution factor
Cd = Resultant magnitude or predicted concentration at edge of mixing zone, ng/L
WQC= Most stringent Alaska marine water quality criterion in ng/L (see additional footnotes)
RP= Reasonable Potential to exceed WQC after mixing
-------
301(h) Tentative Decision: AK0021466
2. Saltwater criteria from Alaska Water Quality Criteria Manual for Toxic and Other Deleterious Organic and Inorganic Substances,
May 15, 2003.
3. Chlorine data was not available; EPA used an assumed Ce of 750 ng/L. See Part IV.A.2 of the Fact Sheet.
4. See Part IV.A.3.C of the Fact Sheet for a discussion of the RPA for copper and silver.
5. Saltwater chronic ammonia criteria were derived from Table IX in Alaska Water Quality Criteria Manual for Toxic And Other
Deleterious Organic and Inorganic Substances using a temperature of 15 °C (facility surface water monitoring 95th percentile value
for trapping depth was 13.7 °C in 2019), a salinity of 10 g/kg (facility surface water monitoring 5th percentile was 5.7 ppt or g/kg at
the trapping depth in 2017), and a pH of 8.0 (facility surface water monitoring 95th percentile value was 7.9 between 2016-2021).
CV was calculated using the 23 data points.
-------
301(h) Tentative Decision: AK0021466
F. TVS Survey Results
Table X. Total Volatile Solids Results (2006)
Sample Location
Date & Time
Method
Total
Volatile
Solids
(TVS)
Units
Station 1-TVS #1
Outfall
8/22/06 16:26
SM2540G
4.5
%
Station 1-TVS #2
Outfall
8/22/06 16:50
SM2540G
4.4
%
Station 2-TVS #1
1000' NW
8/22/06 15:55
SM2540G
4.4
%
Station 2-TVS #2
1000' NW
8/22/06 16:09
SM2540G
4.5
%
Station 3-TVS #1
1000' SE
8/22/06 14:51
SM2540G
4.6
%
Station 3-TVS #2
1000' SE
8/22/06 14:55
SM2540G
4.4
%
Station 4-TVS #1
NW ZID Boundary
8/22/06 15:13
SM2540G
4.4
%
Station 4-TVS #2
NW ZID Boundary
8/22/06 15:25
SM2540G
4.3
%
Station 5-TVS #1
SE ZID Boundary
8/22/06 14:15
SM2540G
4.4
%
Station 5-TVS #2
SE ZID Boundary
8/22/06 14:32
SM2540G
4.3
%
Station 1: Outfall; Stations 2/3: Reference; Stations 4/5: ZID boundary
-------
301(h) Tentative Decision: AK0021466
G. Dilution Modeling Report
The dilution model is available on our website with the other permit documents: https://www.epa.ee es-
permits/npdes-permit-wrangell-wastewater-treatment-plant-alaska
------- |