NC0066711_Draft Permit_20210419

ROY COOPER
Governor
ELIZABETH BISER
Secretary
RICHARD E. ROGERS, JR
Director
NORTH CAROLINA
Ern+Ironmental Quality
April 19, 2022
Mark D. Smith, Operations Manager
Buckeye Terminals, LLC
1312 South Front Street
Wilmington, NC 28401-6117
Subject: NPDES Permit Draft NC0066711
Wilmington Terminal — WPCS Grade PCNC
New Hanover County
Mr. Smith:
The Division of Water Resources (DWR or the Division) reviewed your request to renew the subject permit on
June 21, 2021. We therefore submit this draft permit for your review comment.
Please review the attached carefully to ensure your thorough understanding of the information, permit conditions,
and requirements. This draft includes the following decisions and changes for renewal:
➢ updated text for the Supplement to Permit Cover Sheet.
➢ maintained Turbidity monitoring as Monthly; discontinued permit limits based
on eDMR data, and because the receiving stream is not impaired for Turbidity;
updated Turbidity footnote [Table A. (1)]
➢ maintained TSS with limits; no change from previous
➢ updated text for Section A. (3.), Acute WET test (TGE3E)
➢ maintain Monthly average limits for TSS, per current Permitting Guidance.
➢ per RPA and current permitting guidance, BTEX monitoring continues
without permits limits.
With this notification, the Division will solicit public comment on this draft by publishing a notice in newspapers
having circulation in the general New Hanover County area, per EPA requirements. Please provide your written
comments, if any, to me no later than 30 days after receiving this draft. Note that you must continue to operate
under your existing permit until the effective date of the renewal in progress. Your comments are welcome, but
they are not mandatory.
Following the 30-day public comment period, the Division will review all pertinent comments and take appropriate
action prior to issuing a final permit. If you have questions concerning the draft, please contact the undersigned by
e-mail [[e-mail]].
cc: NPDES Unit
Wilmington Regional Office (WiRO)
ATB, Attn Zach Thomas
OCU, Attn. Maureen Kenney
Sincer
ly,
Jo R. Corpo on, P.G
t �mpliance . d Exp dited Permitting Unit
-DECO
North Carolina Department of Environmental Quality I Division of Water Resources
512 North Salisbury Street 11617 Mail Service Center I Raleigh, North Carolina 27699-1617 — 919.707.3616

Permit NC0066711
STATE OF NORTH CAROLINA
DEPARTMENT OF ENVIRONMENTAL QUALITY
DIVISION OF WATER RESOURCES
PERMIT
TO DISCHARGE WASTEWATER UNDER THE
NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM
(NPDES)
In compliance with the provisions of North Carolina General Statu 1 -215.1, other lawful standards
and regulations promulgated and adopted by the North Car in. ' vironmental Management
Commission, and the Federal Water Pollutio7 of c as amended,
Buckeye Termi
is hereby authorized to discharge
to receiving waters designated as
River Basin in accordance with of
forth in Parts I, II, III and IV hereof
This permit shall become effective
utfalls located at the
ruin
Wilmington
ounty
tributary to the Cape Fear River within the Cape Fear
ations, monitoring requirements, and other conditions set
2022.
This permit and authorization to discharge shall expire at midnight on December 31, 2026.
Signed this day
2022.
Richard E. Rogers. Jr. Director
Division of Water Resources
By Authority of the Environmental Management
Page 1 of 8

Permit NC0066711
SUPPLEMENT TO PERMIT COVER SHEET
All previous NPDES Permits issued to this facility, whether for operation or discharge are hereby
revoked. As of this permit issuance, any previously issued permit bearing this number is no longer
effective. Therefore, the exclusive authority to operate and discharge from this facility arises under the
permit conditions, requirements, terms, and provisions included herein.
Buckeye Terminals, LLC
is hereby authorized to:
1. continue to operate a Water Pollution Prevention Contro
blowdown water, truck and loading rack wash waters
from floor cleaning, this system consisting of
• oil/water separator(s) and,
• an unlined two -stage lagoon
• flow -monitoring device
em ad
ostatic tank`
sing stormwater, boiler
waters, and wash waters
these facilities located at the Bual, 1312 South Front Street,
Wilmington, New Hanover Coun
2. discharge from said treatment works via Outfall 001, at a location specified on the attached map, into
the Cape Fear River (stream segment 18 (71)a], a waterbody in subbasin 03-06-17, currently
classified SC waters within hydrological unit [HUC:030300050503] of the Cape Fear River Basin.
Page 2 of 8

Permit NC0066711
A. (1.)
PART I
EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS
[15A NCAC 02B.0400 et seq., 15A NCAC 02B.0500 et seq.] [WPCS Grade PCNC; 15A NCAC 08G .0302]
Beginning on the effective date of the permit and lasting until expiration, the Permittee is authorized to
discharge from Outfall 001. Such discharges shall be limited, monitored, and reported' by the Permittee
as specified below:
EFFLUENT
CHARACTERISTICS
Parameter Code
LIMITS
MONITORING REQUIREMENTS
Monthly
Average
Daily
Maximum
Measurement
Frequency
Sample
Type 2
Sample
Location
Flow (MGD)
50050
/ Monthly 3
stimate
Effluent
Oil and Grease 4 (mg/L)
EPA Method 1664 (SGT-HEM)
00556
M th y
r
Effluent
Total Suspended Solids
C0530
30.0 mg/L
4 .
thly
Grab
Effluent
Benzene (µg/L)
34030
Z
o
Grab
Effluent
Xylenes Mixture (µg/L)
81551
ly
Grab
Effluent
Toluene (µg/L)
3
Monthly
Grab
Effluent
Ethylbenzene (µg/L)
4371
Monthly
Grab
Effluent
Naphthalene (µg/L)
3 696
>
Monthly
Grab
Effluent
MTBE (µg/L)
22417
/ 1
Quarterly
Grab
Effluent
Turbidity 5
00070
25 NTU
25 NTU
Monthly
Grab
Effluent
Acute Toxicity 6
TGE3E
Annually
Grab
Effluent
Footnotes:
1. The permittee shall submit discharge monitoring reports electronically using the Division's eDMR
system [see A. (4.)].
2. Sampling shall accurately reflect the physical and chemical character of a discharge event, collected
downstream of all treatment facilities, prior to mixing with other waters.
3. Flow — During periods of no flow [no discharge], the Permittee shall submit a signed, monthly
electronic Discharge Monitoring Report (eDMR) indicating "No discharge." Flow may be
documented using any one of the following four (4) methods:
1. measure flow continuously via weir or flow meter (totalizer preferred);
2. estimate flow at 20-minute intervals during the entire discharge event;
3. report flow based on discharge pump logs; or
4. calculate flow based on total rainfall per unit area draining to the outfall using the
Rational Method (see formula, Section A. 2).
Page 3 of 8

Permit NC0066711
4. Oil and Grease — Where possible, the grab sample for oil and grease should be skimmed from the
surface of a quiescent (calm water) zone.
5. Turbidity — Effluent turbidity shall not cause receiving -stream turbidity to exceed 25 NTU. If
background turbidity naturally exceeds 25 NTU, the effluent shall not cause background turbidity to
increase. Any discharge exceeding this permit limit will require sufficient instream sampling
(upstream and/or downstream) to verify compliance, effluent vs. background [NCAC 02B .0220(19)].
6. If an Acute WET test fails [TGE3E], the Permittee shall test each of three (3) subsequent consecutive
discharge events. If resulting tests indicate "pass," the Permittee may resume Quarterly monitoring in
accord with Section A. (3). If after a subsequent five (5) consecutive Quarterly events, WET results
demonstrate no toxicity (i.e., Pass), the Permittee may petition the Division to relax monitoring, as
data may warrant. WET -test samples shall be collected concurrently with sampling other parameters of
concern (POCs), as appropriate to monitoring frequencies.
Conditions:
• The Permittee shall discharge no floating solids or foam v o oth an trace amounts.
• Direct discharge of untreated tank solids, tank botto ' a , or the rag la not permitted.
• The Permittee shall discharge no tank solids, tank botto ater rag -lay- tank/piping test
contents unless Benzene is reported less than :1 ;/L and o en= is reported 1- han 370 µg/L
[per testing limits for Class SC waters.
A. (2.) RATIONAL FLOW
[G.S. 143-215.1(b)]
si
The Rational Method/'Det nati
[REF: FHWA Urba
Q=KuC
Q =
Ku =
C =
I =
flow (peak
unit conversati
nual, 3.2.2. Rational Method (3-1)]
cfs or m3/sec)
tor = 1.008 for U.S. standard units (usually
ignored because it is so close to 1), or 0.278 for metric units
dimensionless runoff coefficient for the watershed, loosely defined
as the ratio of runoff to rainfall
intensity of rainfall [taken from the intensity -duration -frequency
curves for the specified design return period at the time of
concentration, tc (in/h or mm/h). tc = time of concentration (time
after beginning rainfall excess when all portions of the drainage
basin are contributing simultaneously to outlet flow).
A = area of tributary watershed (acres or km2)
The rational equation is used to calculate the runoff from a region, given:
• the runoff coefficient (accounts for infiltration losses in the region),
• the rainfall intensity to the region,
• the time for runoff to travel from the region's upper reaches to its outlet, and
• the region's drainage area.
Page 4 of 8

Permit NC0066711
A. (3.) ACUTE TOXICITY PASS/FAIL - MONITORING ONLY (QUARTERLY)
[15A NCAC 02B .0500 et seq.]
The permittee shall conduct acute toxicity tests on a quarterly basis using protocols defined in the
North Carolina Procedure Document entitled "Pass/Fail Methodology For Determining Acute Toxicity
In A Single Effluent Concentration" (Revised December 2010, or subsequent versions). The monitoring
shall be performed as a Mysid Shrimp (Mysidopsis bahia) 24-hour static test. The effluent concentration
at which there may be at no time significant acute mortality is 90 % (defined as treatment two in the
procedure document). The tests will be performed during the months of January, April, July, and
October. These months signify the first month of each three-month to ,•raty testing quarter assigned to
the facility. Effluent sampling for this testing must be obtained duri
and shall be performed at the NPDES permitted final effluent dis
Should any single quarterly monitoring indicate a failure tmeet specified limits, then monthly
monitoring will begin immediately until such time that . Ingle test is pass d. Upon passing, this
monthly test requirement will revert to quarterly in th nth;ecifiedi ve.
All toxicity testing results required as part of this
the Division's eDMR system for the mont . ' whic
TGE3E. Additionally, DWR Form A
ources
ology Branch
esentative effluent discharge
elow all treatment processes.
will be entered electronically using
, using the parameter code
ollowing address:
Or, results can be sent to the e
Completed Aquatic Toxicity Test h, be filed with the Water Sciences Section no later than 30
days after the end of the reporting per e a 'or which the report is made.
Test data shall be complete, accurate, include all supporting chemical/physical measurements and all
concentration/response data, and be certified by laboratory supervisor and ORC or approved designate
signature.
Total residual chlorine of the effluent toxicity sample must be measured and reported if chlorine is
employed for disinfection of the waste stream.
Should there be no discharge of flow from the facility during a month in which toxicity monitoring is
required, the permittee will complete the information located at the top of the aquatic toxicity (AT) test
form indicating the facility name, permit number, pipe number, county, and the month/year of the report
with the notation of "No Flow" in the comment area of the form. The report shall be submitted to the
Water Sciences Section at the address cited above.
Should the permittee fail to monitor during a month in which toxicity monitoring is required, then
monthly monitoring will begin immediately until such time that a single test is passed. Upon passing,
this monthly test requirement will revert to quarterly in the months specified above. Assessment of
toxicity compliance is based on the toxicity testing quarter, which is the three-month time interval that
Page 5 of 8

Permit NC0066711
begins on the first day of the month in which toxicity testing is required by this permit and continues
until the final day of the third month.
Should any test data from either these monitoring requirements or tests performed by the North Carolina
Division of Water Resources indicate potential impacts to the receiving stream, this permit may be re-
opened and modified to include alternate monitoring requirements or limits.
NOTE: Failure to achieve test conditions as specified in the cited document, such as minimum control
organism survival and appropriate environmental controls, shall constitute an invalid test and will
require immediate follow-up testing to be completed no later than the last day of the month following
the month of the initial monitoring.
A. (4.) ELECTRONIC REPORTING OF DISCHA: 146 TORING REPORTS
[NCGS 143-215.1 (b)]
Federal regulations require electronic submittal of all discharg, snitorin_ reports 1 \I Rs) and program reports.
The final NPDES Electronic Reporting Rule was adopt-d and be.. g e e ' e on De.- 'ber 21, 2015.
NOTE: This special condition supplements or superse
(Standard Conditions for NPDES Permits):
• Section B. (11.) Signatory
• Section D. (2.) Reporting
• Section D. (6.) R
• Section E. (5.)
1.
Re s ortin • Re ' uireme
The permittee shall report disch
Discharge Monitoring Report
r: - monit
e\ ill e
llowi
ections within Part II of this permit
and Section E. 5.
g data electronically using the NC DWR's Electronic
et application.
Monitoring results obtained during the srevious month(s) shall be summarized for each month and submitted
electronically using eDMR. The eDMR system allows permitted facilities to enter monitoring data and
submit DMRs electronically using the internet. Until such time that the state's eDMR application is
compliant with EPA's Cross -Media Electronic Reporting Regulation (CROMERR), permittees will be
required to submit all discharge monitoring data to the state electronically using eDMR and will be required
to complete the eDMR submission by printing, signing, and submitting one signed original and a copy of the
computer printed eDMR to the following address:
NC DEQ / Division of Water Resources / Water Quality Permitting Section
ATTENTION: Central Files
1617 Mail Service Center
Raleigh, North Carolina 27699-1617
If a permittee is unable to use the eDMR system due to a demonstrated hardship or due to the facility being
physically located in an area where less than 10 percent of the households have broadband access, then a
temporary waiver from the NPDES electronic reporting requirements may be granted and discharge
monitoring data may be submitted on paper DMR forms (MR 1, 1.1, 2, 3) or alternative forms approved by
the Director. Duplicate signed copies shall be submitted to the mailing address above. See "How to Request
a Waiver from Electronic Reporting" section below.
Page 6 of 8

Permit NC0066711
Regardless of the submission method, the first DMR is due on the last day of the month following the
issuance of the permit or in the case of a new facility, on the last day of the month following the
commencement of discharge.
Starting on December 21, 2020, the permittee must electronically report the following compliance
monitoring data and reports, when applicable:
• Sewer Overflow/Bypass Event Reports;
• Pretreatment Program Annual Reports; and
• Clean Water Act (CWA) Section 316(b) Annual Reports.
The permittee may seek an electronic reporting waiver from the Division "How to Request a Waiver
from Electronic Reporting" section below).
2. Electronic Submissions
In accordance with 40 CFR 122.41(1)(9), the permittee mu id- ify the initi.. - cipient at the time of each
electronic submission. The permittee should use the EPA ebsite resources tntify the initial recipient
for the electronic submission.
Initial recipient of electronic NPDES information f ted facilities means the entity (EPA or
the state authorized by EPA to impleme PDE o_ . tha e designated entity for receiving
electronic NPDES data [see 40 CFR
EPA plans to establish a web - that
electronic submission an
reporting tool will be a
ht • ://www2.e . a. ov/co
reporting -rule.
ropriate electronic reporting tool for each type of
to access and use the appropriate electronic
NPDES Electronic Reporting Rule is found at:
ischar e-elimination-s stem-n • des -electronic -
Electronic submissions must sta b .te. listed in the "Reporting Requirements" section above.
3. How to Request a Waiver from Electronic Reporting
The permittee may seek a temporary electronic reporting waiver from the Division. To obtain an electronic
reporting waiver, a permittee must first submit an electronic reporting waiver request to the Division.
Requests for temporary electronic reporting waivers must be submitted in writing to the Division for written
approval at least sixty (60) days prior to the date the facility would be required under this permit to begin
submitting monitoring data and reports. The duration of a temporary waiver shall not exceed 5 years and
shall thereupon expire. At such time, monitoring data and reports shall be submitted electronically to the
Division unless the permittee re -applies for and is granted a new temporary electronic reporting waiver by the
Division. Approved electronic reporting waivers are not transferrable. Only permittees with an approved
reporting waiver request may submit monitoring data and reports on paper to the Division for the period that
the approved reporting waiver request is effective.
Information on eDMR and the application for a temporary electronic reporting waiver are found on the
following web page:
http://deq.nc.gov/about/divisions/water-resources/edmr
Page 7 of 8

Permit NC0066711
4. Signatory Requirements [Supplements Section B. (11.) (b) and Supersedes Section B. (11.) (d)1
All eDMRs submitted to the permit issuing authority shall be signed by a person described in Part II, Section
B. (11.)(a) or by a duly authorized representative of that person as described in Part II, Section B. (11.)(b). A
person, and not a position, must be delegated signatory authority for eDMR reporting purposes.
For eDMR submissions, the person signing and submitting the DMR must obtain an eDMR user account and
login credentials to access the eDMR system. For more information on North Carolina's eDMR system,
registering for eDMR and obtaining an eDMR user account, please visit the following web page:
http://deq.nc.gov/about/divisions/water-resources/edmr
Certification. Any person submitting an electronic DMR using the st. 's • 1 MR system shall make the
following certification [40 CFR 122.22]. NO OTHER STATEME S CERTIFICATION WILL BE
ACCEPTED:
"I cert, under penalty of law, that this document and al. at . chments were p - ' . red under my direction or
supervision in accordance with a system designed to assurt quay' : d person • e , roperly gather and
evaluate the information submitted. Based on my ' • . iry oft : , ' . on . r persons i anage the system, or
those persons directly responsible for gathering th - . ation, th- information sub itted is, to the best of
my knowledge and belief true, accurate, and comp : t. away: t t there are significant penalties for
submitting false information, including e p. ibili o i •r'. onment for knowing violations."
5. Records Retention Su s lement
The permittee shall retai
records or copies shall
may be extended by requ
Reports, including eDMR submissions. These
od of at . s : years from the date of the report. This period
time [40 CFR 122.41].
Page 8 of 8

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Buckeye Terminals LLC
Wilmington Terminal, 1312 South Front Street
Latitude:
Lon2itude:
Receiving Stream:
HUC:
Sub -Basin:
34° 13' 08" N
77° 57' 02" W
Cape Fear River
030300050503
03-06-17
State Quad; Wilmington
Permitted Flow: N/A
Drainage Basin: Cape Fear
Stream Class: SC
Facility
Location
(not to scale)
NPDES Permit NC0066711
New Hanover County

FACT SHEET - EXPEDITED PERMIT RENEWALS
This form must be completed by Permit Writers for all expedited permits which do not require full
Fact Sheets. Expedited permits are generally simple, 100% domestics (e.g., schools, mobile home
parks, etc.) or stormwater mixes in secondary containment that can be administratively renewed
with minor changes but can include facilities with more complex issues (Special Conditions, 303(d)
listed water, toxicity testing, instream monitoring, and/or compliance concerns).
Basic Information for Expedited Permit Renewals
Permit Writer/Date
Joe R. Corporon, P. G. 20Apr2022
Permit Number
NC0066711
Permittee
Buckeye Terminals LLC
Facility Name
Buckeye Wilmington Terminal
Facility Address
1312 South Front Street, Wilmington
Facility Type
Contained stormwater in proximity to Bulk Fuel
Surface Storage exceeding 1.00 M. gallons
Site Contacts:
Mark D. Smith, Operations Manager
MSmith@ buckeye.com (?)
[e-mail]
Basin Name/Sub-basin number
Cape Fear / 03-06-17
Receiving Stream
Cape Fear River
Hydrological Unit
HUC:030300050503
Stream Classification in Permit
SC [Tidal]
Does permit need Daily Max NH3 limits?
N/A
Does permit need TRC limits/language?
N/A
Does permit have toxicity testing?
Yes
Does permit have Special Conditions?
Yes
Does permit have instream monitoring?
N/A
Is the stream impaired (on 303(d) list)?
For what parameter?
Yes - Aquatic Life
Any obvious compliance concerns?
No
Any permit mods since last permit?
No
Current expiration date
12/31/2021
New expiration date
12/31/2026
Comments received on Draft Permit?
Peer Review, Emily Richards (NPDES)
• annual fees paid Jan2022 (BIMS)
• registered for eDMRs (BIMS)
• Compliance - DWR has issued no NOVs or CPAs to the
Permittee since a "late DMR" in 2016 (BIMS)
• Established flow max monthly average used for RPA = 0.9214 MGD
• ran RPA on BTEX, Naphthalene, and Xylene Mixture
• ran RPA on Turbidity
Permitting Strategies: This draft permit includes the following decisions and changes for renewal:
➢ updated text for the Supplement to Permit Cover Sheet.
➢ maintained Turbidity monitoring as Monthly; discontinued permit
limits based on eDMR data, and because the receiving stream is not
impaired for Turbidity; updated Turbidity footnote [Table A. (1)]
➢ maintained TSS with limits; no change from previous
➢ updated text for Section A. (3.), Acute WET test (TGE3E)
➢ maintain Monthly average limits for TSS, per current Permitting Guidance.
➢ per RPA and current permitting guidance, BTEX monitoring continues
without permits limits.

PROPOSED SCHEDULE FOR PERMIT ISSUANCE
Draft Permit to Public Notice:
[Tentative] Permit Scheduled to Issue:
[Tentative] Effective date
If you have questions, email [[e-mail]]
19Apr2022
April 19, 2022
June 15, 2022
August 1, 2022
Joe R. C. . oron, P f ., NPD : S Permitting Date
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 1. 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 1 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 2B.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).
Table 2. 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, µg/1
Cadmium, Acute
WER*{1.136672-[ln hardness](0.041838)} • e^{0.9151 [ln
hardness]-3.1485}
Cadmium, Acute Trout
waters
WER* { 1.136672-[ln hardness](0.041838)} • e^ {0.9151 [ln
hardness]-3.6236}
Cadmium, Chronic
WER*{1.101672-[ln hardness](0.041838)} • e^{0.7998[In
hardness]-4.4451 }
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)} • e^ {1.273 [ln hardness]-
1.460 }
Lead, Chronic
WER* { 1.46203-[ln hardness](0.145712)} • e^ {1.273 [ln hardness]-
4.705 }
Nickel, Acute
WER*0.998 • e^{0.8460[ln hardness]+2.255}
Nickel, Chronic
WER*0.997 • e^{0.8460[ln hardness]+0.0584}
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]+0.884}
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.
RPA Permitting Guidance/WQBELs 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.
1. 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 (s7Q10, cfs *Avg. Upstream
Hardness, mg/L)
(Permitted Flow, cfs + s7Q10, cfs)
The Combined Hardness for acute is the same but the calculation uses the 1Q10
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.
EPA default partition coefficients or the "Fraction Dissolved" converts the
value for dissolved metal at laboratory conditions to total recoverable metal
at in -stream ambient conditions. This factor is calculated using the linear
partition coefficients found in The Metals Translator: Guidance for
Calculating a Total Recoverable Permit Limit from a Dissolved Criterion
(EPA 823-B-96-007, June 1996) and the equation:
Cdiss =
Ctotal
1
1 + [Kpo] [SS(1+a)] [10-6]
Where:
ss = in -stream suspended solids concentration [mg/1], minimum of 10 mg/L
used, and
Kpo and a = constants that express the equilibrium relationship between
dissolved and adsorbed forms of metals. A list of constants used for each
hardness -dependent metal can also be found in the RPA program under a
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
(ie. 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.
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 = (s7Q10 + Qw) (Cwqs) — (s7Q10) (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 s7Q 10)
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:
1 Q 10 = 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
6. 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.
7. 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.
8. 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.
9. 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.
10. Hardness and flow values used in the Reasonable Potential Analysis for this permit
included:
Parameter
Value
Comments (Data Source)
Average Effluent Hardness (mg/L)
[Total as, CaCO3 or (Ca+Mg)]
N/A
No metals monitoring
Average Upstream Hardness (mg/L)
N/A
No metals monitoring

[Total as, CaCO3 or (Ca+Mg)]
7Q10 summer (cfs)
0.0
1 Q 10 (cfs)
0.0
Permitted Flow (MGD)
N/A
Flow not limited