Appendix I - Technical Memo - WWTP

Piedmont Lithium Carolinas, Inc. I Response to DEMLR Additional Information Request
Appendices
a
PIEDMONT
LITHIUM
Appendix I: Technical
Memorandum — WWTP
Considerations

DAAO Technical
I E N T
Memorandum
Wastewater Treatment Plant
Considerations
Piedmont Lithium Carolinas, Inc.
Gaston County, North Carolina
November 5, 2021

Piedmont Lithium Carolians, Inc. I Wastewater Treatment Plant Considerations ���
Contents
Contents
Contents ............
Introduction................................................................................................................................ 1
Projected PLCI Wastewater Characteristics............................................................................... 2
TotalWastewater Flow........................................................................................................... 2
Total Wastewater Flow Characteristics................................................................................... 3
Potential Impact of PLCI Wastewater on WWTPs...................................................................... 4
PermittedFlows...................................................................................................................... 4
NC Water Quality Standards.................................................................................................. 5
Effluent Characteristics........................................................................................................... 6
Considerations for Long Creek WWTP................................................................................... 7
Conclusion and Recommendations............................................................................................ 8
Tables
Table 1. Projected Nominal Flow from PLCI Facilities................................................................ 3
Table 2. Combined Wastewater Flow from PLCI........................................................................ 3
Table 3. Existing Plant Flows..................................................................................................... 5
Table 4. Evaluation of Impact of PLCI water on WWTP effluents ............................................... 6

Piedmont Lithium Carolians, Inc. I Wastewater Treatment Plant Considerations ���
Introduction
Introduction
Piedmont Lithium Carolinas, Inc. (PLCI) is proposing to construct an open pit mine in the
Carolina Tin-Spodumene Belt (TSB) of North Carolina where lithium -bearing pegmatites have
been identified. The PLCI Carolina Lithium Project consists of the Concentrate Operations and
the Lithium Hydroxide Conversion Plant (the Site) and is located in the TSB of the Piedmont
physiographic province in south-central North Carolina. The Site is approximately 1,548 acres in
size and is in an unincorporated area of Gaston County on private land surrounding portions of
Hephzibah Church Road, Whitesides Road, and St. Mark's Church Road, approximately 1 mile
east of Cherryville, North Carolina.
The overall Concentrate Operation is composed of three components: the Piedmont Lithium
Carolinas Mine #1, a Concentrate Plant, and an Industrial Minerals Plant. The Piedmont Lithium
Carolinas Mine #1 will consist of four open pits of varying sizes, a waste rock disposal area,
topsoil stockpiles areas, haul roads, and other mine support areas. This process will produce
native overburden and dry -stacked concentrator tails at the Concentrate Plant. PLCI is proposing to
dry -stack the co -mingled mine refuse streams (native overburden and concentrator tails) in the
waste rock disposal area and/or use the refuse for reclamation to backfill the mine pits. The Lithium
Hydroxide Conversion Plant will accept concentrated ore from the Concentrate Plant and
ultimately produce Analcime tailings, which PLCI is also proposing to dry -stack and co -mingle as
mine refuse in the waste rock disposal area. Tailings from either the Concentrate Operation or
Lithium Hydroxide Conversion Plant will be mechanically dewatered and dry stacked; slurry
impoundments are not proposed. This integrated approach (Concentrate Operations and Lithium
Hydroxide Conversion Plant) will allow PLCI to concentrate and convert mined ore to battery -
grade lithium hydroxide within Gaston County, Cleveland County, and surrounding areas.
HDR Engineering Inc. of the Carolinas (HDR) has been tasked with developing an
understanding of potential receiving municipal wastewater treatment plants (WWTPs) that could
accept industrial wastewater discharged from the PLCI chemical conversion process. In order to
evaluate the potential capability of WWTPs to accept the PLCI process water discharge,
National Pollutant Discharge Elimination System (NPDES) permit discharge criteria and size of
receiving streams were evaluated against wastewater characterization parameters developed
by HDR based on production information provided by Primero.' NPDES permit discharge
criteria are based on the North Carolina 15A NCAC 02B Water Quality Standards for Surface
Water and In -Stream Target Values for Surface Waters.2
Four options were identified for possible treatment of the PLCI discharge: the City of
Cherryville's Cherryville WWTP, the City of Gastonia's Long Creek WWTP, the City of Shelby's
First Broad River WWTP, and the City of Lincolnton's Lincolnton WWTP (Figure 1). The
Cherryville WWPT is the closest facility to the PLCI site and was initially considered as the best
option due to proximity; however as discussed herein, the three alternative plants all have larger
18605-MEM-PR-009 C, Primero, dated June 14, 2021
2 https://deq.nc.gov/documents/nc-stdstable-06102019

Piedmont Lithium Carolians, Inc. I Wastewater Treatment Plant Considerations ���
Projected PLCI Wastewater Characteristics
treatment facilities and larger receiving streams. In addition, the larger municipalities have active
industrial pretreatment programs.
LEGEND
Q PLCI Carolina Lithium Project
Wastewater Treatment Plants
r — — — — — — — -- I ' v„ ,p
owa,
0 Miles 4 ��� ,/,'',or�P
of
Lur�di ib.n r°Ff
VCherryville WWTP
(City of Cherryville)
1=a uslon E Lincolnton WWTP
C rouse
1_3,rndak � _ _ _ (City of Lincolnton)
f -
- � '". � - • High
r �
F til.�nl�;
r,
Long Creek WWTP
(City of Gastonia)
4�
t
er:,. tell• "'�c,.
All I I_!4;
Bessemer Crly I .
First Broad River WWTP
(City of Shelby) ` ` Gastonia
Patterson Kinus
�rnngs P.1��unla Jn &ilm�rll
�Rn�i=. i}it.0 nia
Projected PLCI Wastewater Characteristics
Total Wastewater Flow
The PLCI discharge, based on the Primero memo cited above, is projected to be an average of
0.16 mgd (Table 1) for which Tables 2-4 calculations are based and a peak discharge rate of
0.22 mgd (150 gpm) is proposed. The majority of the flow comes from the Lithium Hydroxide
Conversion Plant. A smaller stream of wastewater is also generated from the Concentrate Plant,
with sanitary wastewater being combined with process wastewater at site boundary for a
proposed disposal to a municipal WWTP. Sanitary wastewater was calculated using NC
standards for wastewater production from manufacturing facilities with showers, at a peak
manpower loading of 200 people onsite.
V,

Piedmont Lithium Carolians, Inc. I Wastewater Treatment Plant Considerations ���
Projected PLCI Wastewater Characteristics
Table 1. Projected Nominal Flow from PLCI Facilities
gpm
gpd
mgd
Concentrator Process Wastewater'
28.8
41,472
0.042
Conversion Process Wastewater'
75.5
108,720
0.109
Sanitary Wastewater— Peak
4.9
7,056
0.007
Total:
109
157248
0.158
derived from 18605-CAL-PR-502 Utilities RvB, Primero, dated October 11, 2021
^ calculated using NC standards for wastewater production from manufacturing
facilities with showers, at a peak manpower loading of 200 people onsite
Total Wastewater Flow Characteristics
The projected wastewater characteristics from the PLCI facility are shown below in Table 2.
These are based on the flow from the Concentrator area discharging after pretreatment via
dissolved air flotation and activated carbon adsorption. Due to the high fluoride and organic
carbon concentrations, this pretreatment is necessary. The Concentrator treatment system is
intended to treat water for recycle back to plant resulting in a bleed stream for which constituent
characterization is not available at this; HDR assumed typical removal rates for the process
described and refinement would be necessary when more information is available. The Lithium
Hydroxide water discharge is taken as partially treated water via a
precipitation/clarification/filtration process and includes 12 m3/d of additional solution bleeds and
miscellaneous discharges that are known to be needed but have not been characterized This
projection is based on an updated evaluation that includes the blowdown streams and sanitary
wastewater at the flowrates noted above.
Table 2. Combined Wastewater Flow from PLCI
Parameter
lb/day
mg/L
Sodium
11971
9,137
Chloride
11,413
8,711
Fluoride
17
13
Sulfate
5,470
4,175
Lithium
24
18
Potassium
1,057
807
Phosphate
165
126
Calcium
34
26
Carbonate
139
106
TDS, inorganic
30,289
23,118
TOC
30
23
COD/BOD
81
61
BTEX
0.09
0.067
PAH
0.003
0.003
organic N
4.3
3.3
The sanitary wastewater (sometimes referred to as black water) was projected as having a five-
day biochemical oxygen demand (BOD5) of 250 mg/L, which is a typical standard value. There
are three measurements used to characterize the organic content of wastewater. The one
applied most industrially is total organic carbon (TOC). This is measured by injecting a sample
3

Piedmont Lithium Carolians, Inc. I Wastewater Treatment Plant Considerations ���
Potential Impact of PLCI Wastewater on WWTPs
into a furnace and measuring the resulting carbon dioxide produced. Another measure is the
chemical oxygen demand (COD), which is determined by reacting a sample with a strong
oxidant and measuring the consumption of the oxidant. In theory, there should be a strong
relationship between TOC and COD. The BOD is determined by a test in which a small sample
of wastewater is mixed with an oxygen -containing solution and a seed bacteria source. The test
bottle is sealed and allowed to react for a typical period of 5 days, after which the residual
oxygen concentration is measured, and the depletion of oxygen is used to calculate the BOD5.
Longer periods can be used for this test, which would change the subscript on BOD, but 5 days
is standard. There is typically a correlation for a specific wastewater stream between BOD5 and
COD, but it varies from stream to stream based on the makeup of the organics present. For the
PLCI wastewater, COD was estimated from TOC based on the molecular weights of carbon
versus oxygen. It was further assumed that all COD present was biodegradable, so the BOD is
essentially the same as COD, which is the worst -case condition.
The projections on water quality made by Primero are based on chemical consumption and
mass balance calculations, which in turn are based on assumptions for chemical dosages and
soluble constituents. Laboratory process simulations would provide a clearer definition of water
quality and blowdown flows. In Table 1, the sanitary wastewater and conversion plant (lithium
hydroxide) flow values are nominal flow values, while the remaining flow values listed are
nominal daily values Peak flows are undefined at this point for other operations. For these
reasons, some conservatism should be applied to the interpretation of the wastewater
characteristics.
Potential Impact of PLCI Wastewater on WWTPs
Permitted Flows
Table 3, below, shows the current and permitted flows to each of the wastewater treatment
plants considered, along with the estimated low flow in the receiving stream. Of the WWTPs
considered, the Long Creek WWTP has the highest permitted flow capacity, approximately 10
million gallons per day (mgd) more than the next highest flow capacity. Table 3 (below) ranks
the WWTPs in order of highest flow capacity to least flow capacity. The higher the flow capacity,
the more advantage a WWTP would have for dilution of the influent wastewater.
Table 3 also summarizes the receiving stream minimum flowrates used for NPDES permit limits.
The Long Creek and First Broad River WWTPs have substantially more dilution capability as
their receiving stream flow is larger and would dilute the WWTP effluent to a greater degree,
potentially allowing higher concentrations for some parameters in the effluent discharges (like
sulfate and chloride). Allowable parameter effluent levels are determined by the state modelling
the receiving streams' mixing zone, to ensure enough dilution of a certain discharge parameter
can occur relative to NC stream standards within a short distance of the discharge point.
C!

Piedmont Lithium Carolians, Inc. I Wastewater Treatment Plant Considerations ���
Potential Impact of PLCI Wastewater on WWTPs
Table 3. Existing Plant Flows
Flow
m d
Low Flow'
Instream
Receiving
Current
Rank
Facility
Current
Current
Average
Mam
Waste
Stream
(cfs)
(mgd)
Permit
Average
+ PLCI
Concentration
Long Creek
South Fork
1
WWTP
16
9.3
9.46
27.2
o
19/o
Catawba River
130
84
- Class WS-V
2
First Broad
6
3.24
3.40
11.8
17%
First Broad River
55
36
River WWTP
Class C
Lincolnton
South Fork
3
WWTP
3.5
1.96
2.12
12.75
6.5%
Catawba River
83
54
Class WS-IV
4
Cherryville
2
0.65
0.81
1.5
34%
Indian Creek
g
5.8
WWTP
- Class C
Low flow based on permitted flow and instream waste concentration provided in facility specific NPDES Permits.
Evaluation of the Cherryville WWTP indicates that the flow from PLCI would make up almost
one quarter of the average flow to the treatment plant. Given the projected high concentration of
chlorides and sulfates in the PLCI discharge, Cherryville could not meet the receiving stream
water quality criteria for these parameters if the PLCI discharge is directed there. The dilution
available in Indian Creek is limited and requires that the Cherryville WWTP discharge be close
to the stream water quality standards. By calculation, the chloride concentration in the
Cherryville effluent would be 1,734 mg/L Chloride, versus a stream standard of 250 mg/L.
Therefore, the Cherryville WWPT is removed from consideration.
Based on dilution potential under low flow conditions of receiving streams, particularly for
chlorides in this case, it is highly desirable to convey the PLCI wastewater effluent to the Long
Creek WWTP and undesirable to convey the PLCI water to the Cherryville WWTP.
NC Water Quality Standards
All surface waters in North Carolina are assigned a primary classification by the NC Division of
Water Resources (DWR). All waters must at least meet the standards for Class C (fishable and
swimmable) waters. The other primary classifications provide additional levels of protection for
primary water contact recreation (Class B) and drinking water (Water Supply [WSJ Classes I
through V). The state of North Carolina has established water quality standards for surface
waters and in -stream target value standards .3 These stream standards define the required
quality in the stream, and a WWTP's receiving stream must meet them for its assigned surface
water classification, as approved in a WWTP effluent NPDES permit limits.
• Class C Waters — is the base waters classification for basic protection of aquatic life and
secondary recreation (i.e. fishable and swimmable waters); all waters must at least meet
the standards for Class C Waters;
Class WS-IV Waters — water supply waters used as sources for drinking, culinary, or
food processing purposes where a WS-I, II or III classification is not feasible; usually in
moderately to highly developed watersheds;
3 https://deq.nc.gov/about/divisions/water-resources/planning/classification-standards/surface-water-standards
5

Piedmont Lithium Carolians, Inc. I Wastewater Treatment Plant Considerations ���
Potential Impact of PLCI Wastewater on WWTPs
• Class WS-V Waters — water supply waters which are generally upstream and draining to
Class WS-IV waters or waters used by industry to supply their employees with drinking
water or as waters formerly used as water.
The criteria of concern for receiving streams classified as Class WS IN receiving the PLCI
discharge would include Chloride (230 mg/L), Sulfate (250 mg/L), Methylene Blue Active
Substances (MBAS) (0.5 mg/L), Arsenic (10 pg/L), Benzene (1.10 pg/L), and polynuclear
aromatic hydrocarbons (PAHs) (2.8 qg/L). In comparison, Class C receiving waters have
required water quality for the following criteria: Arsenic (150 pg/L) and Chloride (230 mg/L).
Class C waters are more heavily monitored for metals.
The MBAS test measures the presence of anionic surfactants or detergents to monitor the
potential for foaming. In the biological process employed at all four of the plants noted above,
foaming in the biological system would:
(1) be damaging to the treatment process, as foam formation would limit oxygen transfer;
(2) limit the WWTP's ability to separate solids from liquid by stabilizing small particles; and,
(3) present operational issues that could result in the WWTP not accepting the influent.
The concern is that frothing agents used in flotation would continue to froth once they reach the
WWTP. Any of these WWTPs would likely require a stipulation in a pretreatment permit about
frothing characteristics with a conservative approach of prohibiting discharge of constituents to
the WWTP that would cause foaming.
Effluent Characteristics
An evaluation was made of the potential impact of the PLCI wastewater on the effluent from the
candidate treatment plants (Table 4). The high flow capacity at the Long Creek WWTP provides
the most dilution, and the receiving stream also provides the most dilution as compared to the
First Broad River and Lincolnton WWTPs. For the Long Creek WWTP, the sulfate, chloride and
TDS concentrations are sufficiently low and would likely meet stream standards in the effluent
before considering dilution in the receiving stream. Other parameter concentrations are within or
reasonably close to stream standard values. Those parameters without assigned stream
standards can be evaluated with a whole effluent aquatic toxicity test to account for potential
impacts to aquatic life. Thus, the best fit for the PLCI wastewater is the Long Creek WWTP.
The First Broad River WWTP would be a second choice and is also the furthest from the Site.
Combined with PLCI effluent, the First Broad River WWTP TDS concentration would be two
times the predicted level in the Long Creek WWTP. However, since the First Broad River is
Class C, there is no stream standard for TDS. In communication with the City of Shelby, staff
indicated that the nearest connection point in Shelby's collection system would need to be
upgraded to accept the flow from PLCI.
Table 4. Evaluation of Impact of PLCI water on WWTP effluents
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Piedmont Lithium Carolians, Inc. i Wastewater Treatment Plant Considerations ���
Potential Impact of PLCI Wastewater on WWTPs
Long Creek
Shelby
Lincolnton
Cherryville
Parameter
Units
Stream
Standards
existing
with PLCI
Discharge
existing
with PLCI
Discharge
existing
with PLCI
Discharge
existing
with PLCI
Discharge
effluent
Limits
effluent
Limits
effluent
Limits
effluent
Limits
Flow
mgd
9.3
9.46
16
3.24
3.40
6
1.96
2.12
3.5
0.65
0.81
2
BOD5
mg/L
3
3.1
5 / 10
5.7
5.7
25
5.8
5.8
30
5.6
19
30
Ammonia N
mg/L
0.20
0.20
2/4
4.5
4.3
14.1
0.73
0.7
12
0.1
0.1
2.5
Total N
mg/L
21.1
20.78
17.1
16.7
13.9
13.1
5.02
4.7
Sulfate
mg/L
250
66
134
77
267
246
537.4
55
857.5
Chloride
mg/L
250
56
200
65
465
208
839.8
47
1734.3
TDS
mg/L
1000
223
604
260
1318
830
2485.1
186
4652.5
Fluoride
mg/L
1.8
1.0
1.2
1
1.0
1
1.9
1
3.3
Lithium
mg/L
0.20
0.50
0.20
1.03
0.2
1.5
0.2
3.7
Benzene*
mg/L
0.0011
<0.001
<0.001
0.0058
<0.0085
<0.005
<0.0095
<0.001
<0.013
PAH
mg/L
0.0000028
<0.0001
<0.00014
<0.0325
<0.0325
<0.0089
<0.0089
<0.0001
<0.0006
Note: Values in red are estimated from TDS value and typical distribution in wastewater. Values in blue are based on calculated
COD = BOD, which assumes biodegradability of all organics present in PLCI wastewater.
* Benzene calculated using 100% of BTEX value from Table 2.
Finally, the Lincolnton WWTP may not be a desirable choice, because the smaller WWTP with
the PLCI effluent would have the highest concentrations of sulfate, chloride and TDS. Also, the
Lincolnton WWTP was originally a 6 mgd facility that was downgraded by the NC Department of
Environmental Quality to 3.5 mgd. This downgrade was due to condition of assets within the
WWTP and could indicate a potential infrastructure issue.
Considerations for Long Creek WWTP
The Long Creek WWTP appears to be the best option for the PLCI wastewater; however, based
on the information supplied by Primero, the following parameters still need to be considered and
may become discussion points for a pre-treatment permit: Benzene, PAHs, Fluoride, Lithium,
TDS, and MBAS. In addition, Gastonia will also evaluate any impacts on biosolids utilization
under pretreatment regulations.
Benzene is largely biodegradable and should be effectively removed in the WWTP biological
treatment process; however, the Primero characterization does not include data for benzene.
PAHs are not generally well biodegraded and if further characterization work indicates that PAH
concentrations in the wastewater are problematic, pretreatment for PAH removal may be
required. It is not expected that Fluoride or Lithium would negatively impact the South Fork
Catawba River at the concentrations shown.
MBAS is a concern because the frothing agents used in flotation would continue to froth once
they reach the WWTP, so the potential exists for a foaming issue. Any of these WWTPs would
likely require a stipulation in a pretreatment permit discharge agreement about frothing
characteristics.
Additionally, the anticipated increase in sulfate, chloride and TDS concentrations could have ar
impact on the Long Creek WWTP's toxicity testing; however, only bench scale testwork or
actual testing would accurately determine this. Bench scale testing could be conducted on a
mixture of actual municipal wastewater from the Long Creek WWTP and a synthetic solution of
7

Piedmont Lithium Carolians, Inc. I Wastewater Treatment Plant Considerations ���
Conclusion and Recommendations
PLCI wastewater once the PLCI stream is better characterized. It would be ideal for the mixture
to be subject to the same treatment processes employed at the Long Creek WWTP, which may
be difficult. A literature -based evaluation of potential toxicity issues for a municipal wastewater
and PLCI wastewater mixture is likely effective in lieu of actual treatment per Long Creek
WWTP processes.
It is recommended to pursue connection to Gastonia based on:
• The Long Creek WWTP has a pretreatment program;
• the capacity at Gastonia's Long Creek WWTP is best able to accept the waste stream of
the WWTPs evaluated; and
• the receiving stream (South Fork Catawba River) has the largest flow of all receiving
streams associated with the evaluated WWTPs.
There are two potential connection points to Gastonia's collection system for initial consideration
— one at the Apple Creek Business Industrial Park and one at the High Shoals Lift Station near
Gaston County Landfill (upstream of the Long Creek WWTP). The next steps would be to
continue discussions with Gastonia on connection points, determine alternatives for the
infrastructure needed to convey the waste to the connection point, and then implementation
(design, permitting, construction). It is also recommended that discussions with Gastonia's
pretreatment staff begin soon so that their input can provide direction to furthering a
pretreatment regime, as necessary.
Conclusion and Recommendations
In conclusion, the best WWTP option to discharge PLCI's wastewater would ultimately be to the
Long Creek WWTP. Not only is the WWTP facility equipped to handle the volume and
characteristics of the PLCI wastewater, but the receiving stream also has a flow capacity that
will further dilute the wastewater to desirable stream standards.
It is recommended that a full wastewater characterization be completed as there are some gaps
in PLCI effluent data, including: MBAS and organic alcohol characterization, as well as the
Concentrator treatment plant bleed discharge. If possible, lab analysis of PLCI wastewater
samples of the parameters noted in Table 2 is recommended.
In lieu of a full wastewater characterization, a literature -based review of the impact of the
various components of the PLCI water on the treatment process and potential toxicity impacts
could be conducted. It would be beneficial to discuss this with the City of Gastonia and the Long
Creek WWTP Director prior to initiation to determine if this would be an acceptable way of
characterizing potential toxicity of the combined wastewater.
It is also recommended to initiate discussions with Gastonia's pretreatment staff in advance of
pretreatment permitting and with utility staff to determine potential infrastructure connection
points and routes.
0