NC0090182_Fact Sheet_20230616

Fact Sheet
June 2023 – New NPDES Permit NC0090182
Page 1
NCDENR / DWR / NPDES
EXPEDITED FACT SHEET – NEW NPDES PERMIT
NPDES Permit NC0090182
Joe R. Corporon P.G., Compliance & Expedited Permitting Unit 16Jun2023
Table 1 - Facility Information
Applicant / Facility: Daniel Realty Company, LLC /
Graham & 6th Street
Applicant Contacts:
Andrew Irish, Senior Development Mgr. [[e-mail]];
Camron Conner, VP;
Consultant Joseph P. Nestor, P.G., P.E., [[e-mail]]
Environmental Principal, ECS Southeast Limited LLP
Pauline Burdette, Enviro MGR [[e-mail]]
Facility Address: 301 North Graham & 420 West 6th Street, Charlotte
Flow: Permitted @ 0.075 MGD [proposed treatment as continuous @ 0.050 MGD]
Type of Waste: 100% Industrial - Remediated Groundwater
1) Excavation and, 2) Permanent Structure Dewatering
WET Testing Acute 48-hr, Monthly [TAA6C] - monitor only
Facility Class: Physical/Chemical
PCNC County: Mecklenburg
Permit Status: New Regional Office: MRO
Stream Characteristics
Receiving Stream UT to Irwin Creek Stream Classification C
Stream Segment 11-137-1 Drainage basin Catawba
Summer 7Q10 (cfs) 0 Subbasin 03-08-34
Winter 7Q10 (cfs) 0 Use Support Impaired for fish consumption;
water-column mercury, copper 30Q2 (cfs) 0 303(d) Listed
Average Flow (cfs) 0 State Grid G15NE
IWC (%) 100% USGS Topo Quad Charlotte East, NC
FACILITY SUMMARY - Daniel Realty Company, LLC (the Applicant) proposes to treat groundwater
exposed by excavations below the groundwater table. The dewatering treatment system will support both
excavations and permanent long-term dewatering for permanent subterranean structures. The treatment
system proposes to polish the effluent via granular activated carbon (GAC) filters. Unless modified, the
system consists of:
• one (1) 18,000-gallon frac tank [w/ injector for CO2 gas to adjust pH, as needed. The
CO2 gas system to be removed for permanent (long-term) dewatering unless needed]
• one (1) 1,000-gallon surging tank [w/ recirculating pump, as needed <14,000 GPD]
• two (2) each particle filters [in series]
• two (2) each 1000-pound activated carbon vessels [in series]
• sample ports, as needed, to establish filter contaminant breakthrough
• appurtenant piping, instrumentation, and valving
• totalizing flow meter
• discharge line to stormsewer inlet
RECEIVING STREAM - Outfall 001 will discharge to a stormsewer inlet adjacent to the site on the SW
corner of Graham Street and flow north to surface waters as an unnamed tributary (UT) to Irwin Creek.
Treated effluent shall discharge via Outfall 001 under zero-flow receiving stream conditions [7Q10 and
30Q2 = 0.0 cfs], i.e., this effluent receives no dilution credit from the receiving stream, consistent with
similar discharges statewide. Current stream impact conditions indicate “Fair, Poor or Severe
Bioclassification in its Fish Community and Benthos [DEQ 303d list for 2022].
Fact Sheet
June 2023 – New NPDES Permit NC0090182
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SUMMARY OF GROUNDWATER SAMPLES - ANALYTICAL RESULTS

Table 2: Application list of contaminants detected, and therefore “thought to be present.” *

* DWR notes that BTEX [likely gasoline fuel related] and Naphthalene [likely diesel fuel related]
dominate as contaminants of concern (COCs). Except for chloroform, no other chlorinated solvents have
been detected to date.

ENGINEERING ALTERNATIVES ANALYSIS (EAA)
The Applicant documents their requests for discharge alternatives from local agencies [City of
Charlotte WWTP and Charlotte Water and Sewer Authority], but these agencies have yet to respond,
and did not respond with the allotted 15-day period. The Applicant will provide these
correspondences as they are received.
As required of all new discharges, the Applicant presented an Engineering Alternatives Analysis
(EAA) as Ground surface/subsurface applications including:
• spray/drip irrigation,
• infiltration galleries
• wastewater reuse
• injection wells
After considering the above, the Applicant judged these discharge alternatives “not feasible”
because conditions and suitable land are not available. In consequence, they did not evaluate present
value costs analysis [PVCA]. The EAA further evaluated surface-waters for potentially impacted
species [none known to present] and identifying impaired waters downstream in Irwin Creek [see
Receiving Stream]. They conclude the proposed effluent would make no impact.
Fact Sheet
June 2023 – New NPDES Permit NC0090182
Page 3
ESTABLISHING LIMITS AND MONITORING
Whole Effluent Toxicity (WET) Testing -- This facility proposes to apply granular activated carbon
(GAC) filters as a final effluent treatment. Based on similar treatment systems statewide, DWR considers
that GAC-polished effluent may likely render the discharge devoid of necessary nutrients (too clean) to
support aquatic test species, and therefore may likely fail [see A. (1.)]. DWR has therefore applied WET
testing as Acute 48-hr, Monthly [TAA6C], Monitor and Report only.

RPA – Reasonable Potential Analyses (RPAs) were not conducted because to date, there is no treated
effluent database. The permit reflects site-assessment data only, as provided on the Application for
Discharge.
Establishing Contaminants of Concern (COCs) - COCs are based on analytes “known to be
present” [See EPA Application form 2D] and other potential contaminants. Considering that current
chemical evaluation of local groundwater is limited in scope, DWR has included VOCs and Semi-VOCs
[EPA Methods 624.1 and 625.1 as a spot check for contaminants influent to the treatment system that
remain unestablished [see Permit Section A. (1.) and Special Condition A. (4.)]. Rationale:
• If an analyte is known to be present and has an established surface water quality
standard or criteria, DWR has applied this standard or criteria as the permit limit
[whichever is more stringent], both as acute and chronic limits [see section A. (1.)].
• DWR recommends Monthly monitoring for these organic and inorganic analytes
considering a continuous flow (see permit Section A. (1.)].
• DWR finds no analyses for metals in the current site-assessment database.
Therefore, Total Lead monitoring will be required as may be related to vehicle fuel.
• Metals in dissolved fraction require effluent monitoring for Total Hardness to
established compliance with EPA guidelines.

PROPOSED SCHEDULE FOR PERMIT ISSUANCE:

Public Notice (estimated): June 28, 2023
Issuance (estimated): August 4, 2023
Effective Date (estimated): September 1, 2023

NPDES DIVISION CONTACT

If you have questions regarding any of the above or the attached permit, please contact Joe R.
Corporon, P.G., email preferred [[e-mail]].

NAME: _____ DATE: 16JUN2023

Fact Sheet
June 2023 – New NPDES Permit NC0090182
Page 4

9.0 EPA METALS EVALUATION – for TOTAL HARDNESS

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 3. NC Dissolved Metals Water Quality Standards/Aquatic Life Protection
Parameter Acute FW, µg/l
(Dissolved)
Chronic FW, µg/l
(Dissolved)
Acute SW, µg/l
(Dissolved)
Chronic SW, µg/l
(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 3 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/l for human health protection; cyanide at 5
µg/L and fluoride at 1.8 mg/L for aquatic life protection).
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, µg/l
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[ln 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}
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June 2023 – New NPDES Permit NC0090182
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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.
Fact Sheet
June 2023 – New NPDES Permit NC0090182
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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.

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
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__ = _______1_______________
Ctotal 1 + { [Kpo] [ss(1+a)] [10-6] }

Where:
ss = in-stream suspended solids concentration [mg/l], 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.

Fact Sheet
June 2023 – New NPDES Permit NC0090182
Page 7
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 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

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.
Fact Sheet
June 2023 – New NPDES Permit NC0090182
Page 8
10. 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)] ? TBD
Average Upstream Hardness (mg/L)
[Total as, CaCO3 or (Ca + Mg)] ? TBD
7Q10 summer 0.0 cfs Discharge to storm sewer
1Q10 0.0 cfs “
Permitted Flow (MGD) 0.075 Outfall 001 (per permit)

Daniel Realty Company, Inc. LLC NC0090182/ NEW

Public Notice Blurb:
27Jun2023

Daniel Realty Company, Inc. LLC, operating at the site, 301 N. Graham & 420 West 6th Street,
Charlotte, Mecklenburg County, has applied for new NPDES permit NC0090182 to discharge
remediated groundwater to surface waters of the State. The parameters Chloroform, Benzene,
and Toluene are water-quality limited. This discharge my affect future wasteload allocations to
this portion of the receiving watershed. The Division will accept comments on this draft if
received within 30 days of this notice.