NC0046892_Fact Sheet_20201215

NCDEQ / DWR / NPDES
FACT SHEET - NPDES PERMIT RENEWAL
NPDES Permit NCO046892
Joe R. Corporon, P.G. Compliance & Expedited Permitting Unit 15Dec2020
Facility Information
Applicant/Facility Name
Motiva Enterprises, LLC/Charlotte South Terminal
Applicant Address
410 Tom Sadler Rd, Charlotte NC 28214
Facility Address
6851 Freedom Drive, Charlotte NC 28214
Permitted Flow (MGD)
not limited
Type of Waste
100% Industrial, fuel (bulk storage); treated stormwater
Facility Class
PC-1
County
Mecklenburg
Permit Status
Renewal
Regional Office
MRO
Stream Characteristics
Receiving Stream
UT to Long Creek
Stream Classification
WS-IV
Stream Segment
11-120-(2.5)
Drainage basin
Catawba
Summer 7Q10 (cfs)
0.0
Subbasin
03-08-34
Winter 7Q10 (cfs)
0.0
Use Support
Supporting
30Q2 (cfs)
0.0
303(d) Listed
No
Average Flow (cfs)
0.0
State Grid
F15SW
IWC (%)
100%
USGS Topo Quad
Mt. Island Lake, NC
Facility Summary
Motiva Enterprises, LLC - Charlotte South Terminal (Motiva) is a petroleum fuel -storage and distribution
facility (flow <1 MGD) collecting stormwater via a Surface -Water Pollution Prevention System in
proximity to above -ground storage tanks (ASTs). Facilities are NPDES permitted as surface storage of
petroleum hydrocarbons in excess of one (1) million gallons and fuel -truck loading racks.
The previous permit included a discharge from treating contaminated groundwater still in progress but no
longer discharging under this permit (see renewal application). There are no other significant changes to
this facility since last renewal. Motiva's treatment facilities consist o£
• bermed areas (secondary containment for ASTs);
• oil -water separator [1,500-gallons] - truck -loading rack wastes
disposed off -site at a permitted facility;
• detention pond (with hand -operated discharge valve, normally closed)
Receiving Stream — Outfall 001 discharges to an unnamed tributary (UT) to Long Creek [Stream
Segment 11-120-(2.5)], Class Water Supply WS-IV. The segment is listed as "supporting" in the
2018 North Carolina Integrated report [303(d) list].
Fact Sheet
Renewal Dec2020 -- NPDES Permit NC0046892
Page 1

FLOW DICHARGE HISTORY (MGD) — Jun2015- Ju12020:
Max
Min
Average
Number
2015
1.218
0.009
0.268
24
2016
1.059
0.0007
0.207
21
2017
0.529
0.0018
0.188
25
2018
0.4841
0.0006
0.198
34
2019
0.5885
0.0009
0.2323
27
2020
0.641
0.0011
0.2942
14 [thru 07Ju1 ]
Compliance History — DWR records document that Motiva received no permit violations during the
previous permit cycle (June 2015 through Sep202O).
Whole Effluent Toxicitv (WET) Samnling - Ouarterly vs. Annually. Reauest Denied — For
renewal, Motiva has requested to relax the WET -test frequency from Quarterly to Annually in order to
reduce operating costs [app. cover, page 3 of 3]. However, the Division does not agree that annual
monitoring is sufficiently frequent to evaluate the potential environmental impact of this discharge (24
to 48 discharge events per year) — no changes recommended.
Reasonable Potential Analysis (RPA) -- Based on test results and reasonable potential
analyses (RPAs), DWR has relaxed monitoring and removed permit limits for some previous
parameters ofconcern. Results recommend discontinuing monitoring for Total Recoverable
Phenolics, Toluene, Ethylbenzene, MTBE and Naphthalene due to non -detect data above the
rest -limit PQL. However, Benzene's database continues to show reasonable potential to exceed
its surface water -quality standard, therefore monitoring continues for Benzene with permit
limits equal to the standard [zero -flow receiving -stream conditions], see section A. (L).
Renewal Summary —
• updated permit text and facility map
• Benzene monitoring continues with limit based on RPA
• Monitoring discontinued for Total Recoverable Phenolics, Toluene,
Ethylbenzene, MTBE and Naphthalene)
• Acute Toxicity, Quarterly (Ceriodaphnia dubia) Pass/Fail, limited [no changes]
• Electronic Reporting text updated
Proposed Schedule:
Public Notice (estimated):
Issuance (estimated):
Effective Date (estimated):
December 22, 2020
February 5, 2021
March 1, 2021
Fact Sheet
Renewal Dec2020 -- NPDES NCO046892
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NPDES DIVISION CONTACT
If you have questions regarding any of the above or the attached permit, please contact Joe R.
Corporon, P.G., email [e-mail]].
NAW
TE: 15DEc2020
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-[ln hardness] (0.041838)1 - e^{0.9151 [In hardness]-3.14851
Cadmium, Acute Trout waters
WER* 11.136672-[ln hardness](0.041838)1 - e^{0.915l [ln hardness]-3.62361
Cadmium, Chronic
WER* { 1.101672-[ln hardness](0.041838)1 - e^{0.7998[ln hardness]-4.44511
Chromium III, Acute
WER*0.316 e^{0.8190[ln hardness]+3.72561
Chromium III, Chronic
WER*0.860 e^{0.8190[ln hardness]+0.68481
Copper, Acute
WER*0.960 e^{0.9422[ln hardness]-1.7001
Copper, Chronic
WER*0.960 e^{0.8545[ln hardness]-1.7021
Lead, Acute
WER* 11.46203-[ln hardness] (0. 145712)1 • e^{1.273[In hardness]-1.4601
Lead, Chronic
WER* 11.46203-[ln hardness](0.145712)1 • e^{1.273[ln hardness]-4.7051
Nickel, Acute
WER*0.998 e^{0.8460[ln hardness]+2.2551
Nickel, Chronic
WER*0.997 e^{0.8460[ln hardness]+0.05841
Silver, Acute
WER*0.85 • e^{1.72[ln hardness]-6.591
Silver, Chronic
Not applicable
Zinc, Acute
WER*0.978 e^{0.8473[ln hardness]+0.8841
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.
Fact Sheet
Renewal Dec2020 -- NPDES NC0046892
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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.
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 1 Q 10 using the formula 1 Q 10 = 0.843 (s7Q 10, 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.
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Renewal Dec2020 -- NPDES NC0046892
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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,
Ing/1-1
(Permitted Flow, cfs + s7Q10, cfs)
The Combined Hardness for acute is the same but the calculation uses the 1Q10 flow.
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 - I
Ct.w 1 + f [Kp.] [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 sheet labeled DPCs.
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.
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Renewal Dec2020 -- NPDES NCO046892
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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 = (s7Q 10 + Qw) (Cwgs) — (s7Q 10) (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)
s7Q 10 = 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 s7Q 10 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
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.
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Renewal Dec2020 -- NPDES NCO046892
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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)]
Average Upstream Hardness
(mg/-)
[Total as, CaCO3 or (Ca + Mg)]
7Q10 summer (cfs)
1 Q 10 (cfs)
Permitted Flow (MGD)
0.450 MGD
Outfall 001 (per permit)
Fact Sheet
Renewal Dec2020 -- NPDES NC0046892
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