NC0027341_Fact Sheet_20240401

DEQ/ DWR / NPDES
EXPEDITED FACT SHEET - NPDES PERMIT DEVELOPMENT
NPDES Permit NCO027341
Joe R. Corporon P.G., Compliance & Expedited Permitting Unit updated 27Mar2024
Facility Information
Applicant:
Tennessee Valley Authority (TVC)
Facility Name:
Fontana Hydro Plant
EPA ID Number:
NC6640006650
Facility Address:
Power House Road (off NC-28), near Fontana Village, NC 28733
Mailing Address:
1101 Market Street LP, 2K-C, Chattanooga, TN 37402
Facility Contact:
Jacinda B. Woodward, Senior VP, Power Operations 423-751-2022
Obwoodward tva.gov]
Contact Address:
1101 Market Street LP,2K-C, Chattanooga, TN 37402
Facility Operator:
Eric D. Hamby, Fontana Plant Manager [[e-mail]]
Permitted Flow (MGD)
Not limited
Type of Waste:
100% industrial; cooling waters and wastewaters.
SIC Code:
SIC: 4911 / Primary: 48
Facility Class:
PCNC
County:
Graham
Permit Status:
Renewal
Regional Office:
ARO
Stream Characteristics
Receiving Stream:
Little Tennessee River
(Cheoah Lake,
Calderwood Lake
Stream Classification
C; Tr
Stream Segment:
2-(167)
Drainage basin
Temperature, and
pH
Summer 7Q10 (cfs)
—
Subbasin
HUC
04-04-02
060102040401
Winter 7Q10 (cfs)
—
Use Support
2014: 2-(167)a:
Supporting (Cat 2)
30Q2 (cfs)
—
303(d) Listed
Average Flow (cfs)
—
State Grid
F3NW
IWC (%)
—
USGS Topo Quad
Fontana Dam, NC
FACILITY SUMMARY: The Tennessee Valley Authority (TVC) Fontana Hydro Plant produces
electricity via hydraulic turbine generation. Production averages 2,548 megawatt -hours per day, with peak
power generation at 7,051 megawatt -hours per day.
Permitted Outfalls Monthly Ave. Flow (gad)
001: station pump flow
from wheel pit leakage and powerhouse floor drains 1,872,000
002: discharge unwatering sump water 4,890,000
003, 004 &-005: discharge non -contact cooling water 3,900,000
006: discharge lower, intermediate, and upper gallery's leakage 163,000
Total 10,825,000
Fact Sheet
Renewal Mar202418 -- NPDES Permit NCO027341
Page 1

PARAMETERS OF CONCERN SUMMARY — BY OUTFALL:
For Outfalls 001, 002 & 006:
LIMITS
MONITORING REQUIREMENTS t
EFFLUENT CHARACTERISTICS
Sample
[parameter codes]
Monthly
Daily
Measurement
Sample
2
Average
Maximum
Frequency
Type
Location
Flow (MGD)
50050
Monitor & Report a
Quarterly
Estimate
E
Free Oil Visual Sheen (yes=1 no=0) 3 ' 4
51689
Monitor & Report
Quarterly
Estimate
E
pH (su) 4,5,6
00400
Monitor & Report 6' b
Footnotes 4, 5
Grab c
E
Oil & Grease (O&G) (mg/L) 4 ' 5
00556
15 mg/L d
20 mg/L d
Footnotes 4, 5
Grab c
E
For Outfall 003, 004 & 005:
EFFLUENT CHARACTERISTICS
[parameter codes]
LIMITS
MONITORING REQUIREMENTS t
Monthly
Avera a
Daily
Maximum
Measurement
Frequency
Sample
T e
Sample
Location
Flow (MGD)
50050
Monitor & Report 9
Semi-annually
Estimate
E
Temperate (°C) 3
00010
Monitor & Report 3, h
Semi-annually
Grab
E
pH (su) 4
00400
Monitor & Report 4'
Semi-annually
Grab'
E
Data Review - Reasonable Potential Analyses (RPAs) — Monitoring includes Flow, pH, Oil &
Grease, and Temperature. There are no parameters of concern that require RPA in this permit.
COMPLIANCE HISTORY: BIMS lists no compliance issues for the past five (5) years.
RENEWAL SUMMARY: The Division has made no changes for this renewal except to update permit text
PROPOSED SCHEDULE FOR PERMIT ISSUANCE
Draft to Public Notice:
April 2, 2024
Submit Permit final for signature [estimated]:
May 3, 2024
Permit Issue [estimated]:
May 17, 2024
Effective Date [estimated]:
July 1, 2024

NPDES DIVISION CONTACT
If you have questions about the above information, or about the attached permit, please email Joe
R. Corporon, P.G. [e-mail]].
DATE: 27Mar2024
NPDES Implementation of Instream Dissolved Metals Standards — Freshwater Standards
The NC 2007-2015 Water Quality Standard (WQS) Triennial Review was approved by the NC
Environmental Management Commission (EMC) on November 13, 2014. The US EPA subsequently
approved the WQS revisions on April 6, 2016, with some exceptions. Therefore, metal limits in draft permits
out to public notice after April 6, 2016 must be calculated to protect the new standards - as approved.
Table 2. NC Dissolved Metals Water Quality Standards/Aquatic Life Protection
Parameter
Acute FW, µg/1
(Dissolved)
Chronic FW, µg/1
(Dissolved)
Acute SW, µg/1
(Dissolved)
Chronic SW, µg/1
(Dissolved)
Arsenic
340
150
69
36
Beryllium
65
6.5
---
---
Cadmium
Calculation
Calculation
40
8.8
Chromium III
Calculation
Calculation
---
---
Chromium VI
16
11
1100
50
Copper
Calculation
Calculation
4.8
3.1
Lead
Calculation
Calculation
210
8.1
Nickel
Calculation
Calculation
74
8.2
Silver
Calculation
0.06
1.9
0.1
Zinc
Calculation
Calculation
90
81
Table 2 Notes:
1. FW= Freshwater, SW= Saltwater
2. Calculation = Hardness dependent standard
3. Only the aquatic life standards listed above are expressed in dissolved form. Aquatic life standards
for Mercury and selenium are still expressed as Total Recoverable Metals due to bioaccumulative
concerns (as are all human health standards for all metals). It is still necessary to evaluate total
recoverable aquatic life and human health standards listed in 15A NCAC 213.0200 (e.g., arsenic at
10 µg/1 for human health protection; cyanide at 5 µg/L and fluoride at 1.8 mg/L for aquatic life
protection).
Fact Sheet
Renewal 2024 -- NPDES NCO027341
Page 3

Table 3. Dissolved Freshwater Standards for Hardness -Dependent Metals
The Water Effects Ratio (WER) is equal to one unless determined otherwise under 15A NCAC
02B .0211 Subparagraph (11)(d)
Metal
NC Dissolved Standard, 1
Cadmium, Acute
WER*{1.136672-[In hardness] (0.041838)) e^{0.9151 [1n hardness]-
3.1485}
Cadmium, Acute Trout
waters
WER* { 1.136672-[ln hardness] (0.041838)}
3.6236}
e^{0.9151 [ln hardness] -
Cadmium, Chronic
WER*{1.101672-[In hardness] (0.041838)}
4.4451 }
e^{0.7998[ln hardness]-
Chromium III, Acute
WER*0.316 e^{0.8190[ln hardness] +3.7256}
Chromium III, Chronic
WER*0.860 e^{0.8190[ln hardness]+0.6848}
Copper, Acute
WER*0.960 e^{0.9422[ln hardness]-1.700)
Copper, Chronic
WER*0.960 e^{0.8545[ln hardness]-1.702)
Lead, Acute
WER* { 1.46203-[ln hardness](0.145712)}
1.460 }
e^{ 1.273[ln hardness]-
Lead, Chronic
WER*{1.46203-[In hardness](0.145712)}
4.705 }
e^{1.273[ln hardness]-
Nickel, Acute
WER*0.998 e^{0.8460[ln hardness]+2.255}
Nickel, Chronic
WER*0.997 e^{0.8460[ln hardness] +0.05 84)
Silver, Acute
WER*0.85 • e^{ 1.72[ln hardness]-6.59}
Silver, Chronic
Not applicable
Zinc, Acute
WER*0.978 e^{0.8473[ln hardness] +0.884}
Zinc, Chronic
WER*0.986 e^{0.8473[ln hardness] +0. 8841
General Information on the Reasonable Potential Analysis (RPA)
The RPA process itself did not change as the result of the new metals standards. However, application of
the dissolved and hardness -dependent standards requires additional consideration in order to establish the
numeric standard for each metal of concern of each individual discharge.
The hardness -based standards require some knowledge of the effluent and instream (upstream) hardness and
so must be calculated case -by -case for each discharge.
Metals limits must be expressed as `total recoverable' metals in accordance with 40 CFR 122.45(c). The
discharge -specific standards must be converted to the equivalent total values for use in the RPA
calculations. We will generally rely on default translator values developed for each metal (more on that
below), but it is also possible to consider case -specific translators developed in accordance with established
methodology.
I ,Ik vt

RPA Permitting Guidance/WOBELs for Hardness -Dependent Metals - Freshwater
The RPA is designed to predict the maximum likely effluent concentrations for each metal of concern,
based on recent effluent data, and calculate the allowable effluent concentrations, based on applicable
standards and the critical low -flow values for the receiving stream.
If the maximum predicted value is greater than the maximum allowed value (chronic or acute), the
discharge has reasonable potential to exceed the standard, which warrants a permit limit in most cases. If
monitoring for a particular pollutant indicates that the pollutant is not present (i.e. consistently below
detection level), then the Division may remove the monitoring requirement in the reissued permit.
To perform a RPA on the Freshwater hardness -dependent metals the Permit Writer compiles the
following information:
• Critical low flow of the receiving stream, 7Q10 (the spreadsheet automatically calculates
the 1Q10 using the formula 1Q10 = 0.843 (s7Q10, cfs) 0.993
• Effluent hardness and upstream hardness, site -specific data is preferred
• Permitted flow
• Receiving stream classification
2. In order to establish the numeric standard for each hardness -dependent metal of concern and for
each individual discharge, the Permit Writer must first determine what effluent and instream
(upstream) hardness values to use in the equations.
The permit writer reviews DMR's, Effluent Pollutant Scans, and Toxicity Test results for any
hardness data and contacts the Permittee to see if any additional data is available for instream
hardness values, upstream of the discharge.
If no hardness data is available, the permit writer may choose to do an initial evaluation using a
default hardness of 25 mg/L (CaCO3 or (Ca + Mg)). Minimum and maximum limits on the
hardness value used for water quality calculations are 25 mg/L and 400 mg/L, respectively.
If the use of a default hardness value results in a hardness -dependent metal showing reasonable
potential, the permit writer contacts the Permittee and requests 5 site -specific effluent and upstream
hardness samples over a period of one week. The RPA is rerun using the new data.
The overall hardness value used in the water quality calculations is calculated as follows:
Combined Hardness (chronic) _
(Permitted Flow, cfs *Avg. Effluent Hardness, mg/L) x (s7010, cfs *Avg. Upstream Hardness, mg/L)
(Permitted Flow, cfs + s7Q10, cfs)
The Combined Hardness for acute is the same but the calculation uses the IQ 10 flow.
3. The permit writer converts the numeric standard for each metal of concern to a total recoverable
metal, using the EPA Default Partition Coefficients (DPCs) or site -specific translators, if any have
been developed using federally approved methodology.
4. The numeric standard for each metal of concern is divided by the default partition coefficient (or
site -specific translator) to obtain a Total Recoverable Metal at ambient conditions.
In some cases, where an EPA default partition coefficient translator does not exist (i.e. silver), the
dissolved numeric standard for each metal of concern is divided by the EPA conversion factor to
obtain a Total Recoverable Metal at ambient conditions. This method presumes that the metal is
dissolved to the same extent as it was during EPA's criteria development for metals. For more
information on conversion factors see the June 1996 EPA Translator Guidance Document.
Pact Sheet
Renewal 2024 -- NPDES NC0027341
Page 5

The RPA spreadsheet uses a mass balance equation to determine the total allowable concentration (permit
limits) for each pollutant using the following equation:
Ca = (s7010 + Ow) (,Cwgs) — (s7O10) (Cb)
Qw
Where: Ca = allowable effluent concentration (µg/L or mg/L)
Cwqs = NC Water Quality Standard or federal criteria (µg/L or mg/L)
Cb = background concentration: assume zero for all toxicants except NH3* (µg/L, or mg/L)
Qw = permitted effluent flow (cfs, match s7Q10)
s7Q10 = summer low flow used to protect aquatic life from chronic toxicity and human health
through the consumption of water, fish, and shellfish from noncarcinogens (cfs)
* Discussions are on -going with EPA on how best to address background concentrations
Flows other than s7Q10 may be incorporated as applicable:
1Q10 = used in the equation to protect aquatic life from acute toxicity
QA = used in the equation to protect human health through the consumption of water, fish,
and shellfish from carcinogens
30Q2 = used in the equation to protect aesthetic quality
5. The permit writer enters the most recent 2-3 years of effluent data for each pollutant of concern.
Data entered must have been taken within four and one-half years prior to the date of the permit
application (40 CFR 122.21). The RPA spreadsheet estimates the 95th percentile upper
concentration of each pollutant. The Predicted Max concentrations are compared to the Total
allowable concentrations to determine if a permit limit is necessary. If the predicted max exceeds
the acute or chronic Total allowable concentrations, the discharge is considered to show reasonable
potential to violate the water quality standard, and a permit limit (Total allowable concentration) is
included in the permit in accordance with the U.S. EPA Technical Support Document for Water
Quality -Based Toxics Control published in 1991.
6. When appropriate, permit writers develop facility specific compliance schedules in accordance with
the EPA Headquarters Memo dated May 10, 2007 from James Hanlon to Alexis Strauss on 40 CFR
122.47 Compliance Schedule Requirements.
7. The Total Chromium NC WQS was removed and replaced with trivalent chromium and hexavalent
chromium Water Quality Standards. As a cost savings measure, total chromium data results may be
used as a conservative surrogate in cases where there are no analytical results based on chromium
III or VI. In these cases, the projected maximum concentration (95th %) for total chromium will be
compared against water quality standards for chromium III and chromium VI.
8. Effluent hardness sampling and instream hardness sampling, upstream of the discharge, are inserted
into all permits with facilities monitoring for hardness -dependent metals to ensure the accuracy of
the permit limits and to build a more robust hardness dataset.
9. Hardness and flow values used in the Reasonable Potential Analysis for this permit included:
Table 4- Parameter
Value
Comments (Data Source)
Average Effluent Hardness (mg/L)
[Total as, CaCO3 or (Ca+Mg)]
N/A
Discontinued metals monitoring
Average Upstream Hardness (mg/L)
[Total as, CaCO3 or (Ca+Mg)]
N/A
Discontinued metals monitoring
7Q10 summer (cfs)
Tidal
N/A
1Q10 (cfs)
Tidal
N/A
Permitted Flow (MGD)
Not limited
Fact Sheet
Renewal 2024 -- NPDES NC0027341
Page 6