Appendix K - Technical Memorandum – Evaluation of Mine Pit Operations on Water Quality

Piedmont Lithium Carolinas, Inc. I North Carolina Mining Permit Application
Appendices
PIEDMONT
LITHIUM
Appendix K: Technical
Memorandum — Evaluation of
Mine Pit Operations on Water
Quality

DAAONT Technical
NEMemorandum
Evaluation of Mine Pit Operations on
Water Quality
Piedmont Lithium Carolinas, Inc.
Gaston County, North Carolina
August 30, 2021

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Piedmont Lithium Carolinas, Inc. I Technical Memorandum — Evaluation of Mine Pit Operations on Water Quality
Contents
Contents
1 Introduction....................................................................................................................... 1
2 Data Comparison.............................................................................................................. 1
2.1 Groundwater..............................................................................................................1
2.1.1 Groundwater Levels.......................................................................................................... 2
2.1.2 Groundwater Quality......................................................................................................... 2
2.1.3 Leaching Potential of Tailings........................................................................................... 3
2.2 Surface Water............................................................................................................ 4
2.2.1 Surface Water Flow.......................................................................................................... 4
2.2.2 Surface Water Quality....................................................................................................... 5
2.3 Comparison of Groundwater and Surface Water Quality ............................................ 5
3 Conclusions...................................................................................................................... 7
4 References....................................................................................................................... 8
Tables
Table 1. Well construction details............................................................................................... 2
Table 2. Model Predicted Dewatering Withdrawal Rates (HDR, 2021 a) ..................................... 5
Table 3. Comparison of groundwater and surface water samples .............................................. 6
Figures
Figure 1 — Sample and Measurement Points Location Map
Figure 2 — Plots of Groundwater Elevations Over Time
Figure 3 — Box and Whisker of Groundwater Elevations
Figures 4a through 4n — Box and Whisker of Groundwater and Surface Water Quality Data
Figure 5 — Measured and Modeled Stream Flow

Piedmont Lithium Carolinas, Inc. I Technical Memorandum — Evaluation of Mine Pit Operations on Water Quality ���
Contents
List of Acronyms
2L
NCDEQ 15A NCAC 02L .0202 groundwater standards
DWM
Division of Waste Management
HDR
HDR Engineering, Inc. of the Carolinas
IMAC
Interim Maximum Allowable Concentrations
UGH
Lithium hydroxide
MCC
Maximum Concentration of Contaminants
MO
Metso-Outotec
NCDEQ
North Carolina Department of Environmental Quality
PACE
Pace Analytical Services, LLC
PCB
polychlorinated biphenyls
PSRG
Preliminary Soil Remediation Goals
PLCI
Piedmont Lithium Carolinas, Inc.
RCRA
Resource Conservation and Recovery Act
SVOC
Semi -volatile Organic Compounds
TCLP
Toxicity Characteristic Leaching Procedures
TSB
Tin-Spodumene Belt
USEPA
Environmental Protection Agency
VOC
Volatile Organic Compounds

Piedmont Lithium Carolinas, Inc. I Technical Memorandum — Evaluation of Mine Pit Operations on Water Quality ���
Introduction
1 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 approximately 1,548-acre Site 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 one mile east of Cherryville, North Carolina. Planned
mine operations will consist of the Piedmont Lithium Carolinas Mine #1, a Concentrate Plant, an
Industrial Minerals Plant, and a Lithium Hydroxide Conversion Plant. This process will produce
native overburden and dry -stacked concentrator tails at the Concentrator Plant as well as inert
analcime residue from the Lithium Hydroxide Conversion Plant. PLCI is proposing to dry -stack the
co -mingled mine refuse streams (native overburden, concentrator tails, and analcime residue) in the
waste rock disposal area and/or use the refuse for reclamation to backfill the mine pits.
In advance of mine development Piedmont Lithium Carolinas, Inc. (PLCI) commissioned HDR
Engineering, Inc. (HDR) to develop and implement a baseline groundwater and surface water
monitoring program to evaluate naturally -occurring conditions. In addition, HDR obtained one
sample of analcime tailings produced in a microcosm study that mimicked potential lithium
hydroxide conversion operations, for the purpose of testing to evaluate use of tailings as
reclamation material. The analcime tailings were characterized as non -hazardous per Toxicity
Characteristic Leaching Procedure (TCLP) testing.
2 Data Comparison
2.1 Groundwater
HDR compared groundwater elevation and quality data, surface water quality data, and toxicity
testing data, in conjunction with anticipated dewatering rates and periods to evaluate potential
effects of mine pit dewatering on water quality within the mine pit boundaries. Between June
2018 and February 2020, PLCI implemented a baseline groundwater and surface water flow
and quality monitoring program to assess existing conditions prior to potential development of
the mine site. These activities consisted of the installation of five monitoring wells (MW-1
through MW-5), one aquifer test pumping well (PW-1), and four aquifer test observation wells
(OW-1 S, OW-1 D, OW-2S, and OW-21D). Subsequent to installation of monitoring and
observation wells in 2018, HDR conducted 17 groundwater gauging events, 12 groundwater
sampling events, 2 surface water flow monitoring events, and 12 surface water sampling events,
and 1 aquifer pumping test. Construction and geologic details for monitoring wells installed
during this program are presented in Table 1.

Piedmont Lithium Carolinas, Inc. i Technical Memorandum — Evaluation of Mine Pit Operations on Water Quality ���
Data Comparisons
Table 1. Well construction details
Well ID Top of Casing (Feet msl) Depth (Feet) Geologic Material
PW-1
756.75
500
Amphibolite
MW-1
762.49
110
Amphibolite/Pegmatite
MW-2
864.49
110
Amphibolite/Pegmatite
MW-3
840.39
170
Amphibolite
MW-4
884.97
153
Biotite Gneiss
MW-5
756.75
152
Amphibolite
OW-1S
760.63
60
Unconsolidated Regolith
OW-1 D
761.14
302
Amphibolite
OW-2S
755.87
30
Unconsolidated Regolith
OW-2D 755.05 300 Amphibolite
2.1.1 Groundwater Levels
Groundwater levels were measured, and groundwater elevations were calculated, in each well
during 17 well gauging events conducted between August 2018 and February 2020. Water
levels collected during this time indicate that seasonal fluctuations in groundwater elevations
were evident throughout the monitoring period. In general, groundwater elevations increased in
fall and winter months, and decreased in spring and summer months, as would be expected in
the Piedmont Region of North Carolina. Based on these data, well MW-3 exhibited the widest
range of groundwater elevation fluctuation (about 10 feet), while well MW-1 exhibited the
smallest range of fluctuation (less than 4 feet). Groundwater elevations across the Site ranged
from approximately 850 feet mean sea level (msl) at MW-4 to about 740 feet msl in MW-1.
Groundwater elevations were plotted by month for each well and are shown on Figures 2a and
2b. Box and whisker plots for bedrock and overburden wells were generated to show the range
of groundwater elevations in each well (Figures 3a and 3b).
2.1.2 Groundwater Quality
Monitoring wells were purged and sampled during 12 sampling events between August 2018
and February 2020. Additionally, pH field measurements were observed above and below the
North Carolina Department of Environmental Quality (NCDEQ) groundwater quality standard
(21- Standard) range of 6.5-8.5 standard units (SU) in each of the wells during the monitoring
period (Figure 4a). Baseline groundwater and surface water monitoring is documented in the
Technical Memorandum - Water Quality Testing (HDR, 2020).
Concentrations of arsenic, chromium, lead, manganese, and fluoride that exceeded the 2L
Standards were reported in wells MW-2, MW-5, OW-1 D, OW-2S, and PW-1 during the
monitoring period. Box and whisker plots for each constituent that exceeded 2L Standards were
generated and are presented in Figures 4b, 4c, 4d, 4e, and 4f, respectively.
Barium, cadmium, lithium, mercury, selenium, chloride, and sulfate were detected in at least one
sample above the laboratory reporting limit, but below the respective regulatory standards
during the monitoring period, as shown in Figures 4g, 4h, 4i, 4j, 4k, 41, and 4m, respectively.

Piedmont Lithium Carolinas, Inc. I Technical Memorandum — Evaluation of Mine Pit Operations on Water Quality ���
Data Comparisons
2.1.3 Leaching Potential of Tailings
As documented in the Technical Memorandum — Toxicity Testing of Lithium Hydroxide
Conversion Plant Tailings (HDR, 2021), PLCI commissioned Metso-Outotec (MO) to replicate ore
concentrate conversion methods to be undertaken by PLCI during operation of the proposed
Lithium Hydroxide Conversion Plant through bench -scale testing to convert spodumene
concentrate into battery -grade lithium hydroxide (LiOH). On behalf of PLCI, HDR obtained one
sample of the Analcime tailings produced by the MO study to characterize the material via
Toxicity Characteristic Leaching Procedures (TCLP).
The pH of the fluid used for the TCLP analysis had an initial pH of 5.45 Standard Units (SU) and
a final pH of 2 SU. Aluminum and calcium leached from the MO sample at concentrations above
the laboratory reporting limit; however, neither constituent has a 2L Standard or United States
(U.S.) Environmental Protection Agency (EPA) Maximum Concentration of Contaminants (MCC)
for toxicity characteristic testing. Arsenic, barium, beryllium, copper, magnesium, manganese,
strontium, titanium, and zinc leached at estimated concentrations (J-values) above the method
detection limit established by USEPA, but below the laboratory reporting limit. For this Technical
Memorandum, TCLP results for select constituents were plotted on the box and whisker plots
for arsenic (Figure 4b) and barium (Figure 4g).
2.1.3.1 ARSENIC
A total of 120 groundwater samples were analyzed for arsenic during the monitoring period;
arsenic was detected 8 times, each time at a concentration that exceeded the 2L Standard.
Arsenic exceedances occurred in samples obtained from MW-5 and PW-1 during the monitoring
period.
Arsenic was detected in the granular material (MO sample) used for the TCLP testing, but at an
estimated concentration of 0.96J mg/kg. Arsenic leached from the granular sample at a
concentration 0.22J Ng/L. Both concentrations were below the laboratory reporting limits.
Arsenic is mobile under reducing conditions and rock type and high pH can contribute to
elevated concentrations of arsenic in groundwater (USGS, 2021). Groundwater samples from
MW-5 and PW-1 had pH levels above the 2L Standard (range of 6.5 to 8.5) in sampling events
that corresponded to elevated concentrations of arsenic, indicating that while arsenic may be
naturally occurring at the Site, it also may be biased high by high pH in the groundwater.
Arsenic was not detected in any of the surface water samples collected from the Site.
Well MW-5 was completed as a Type III well with a 2-inch diameter well set within a 6-inch
diameter outer casing. The outer casing was set into the top of competent bedrock and grouted
in place to reduce vertical migration of groundwater from the regolith aquifer into fractured
bedrock. One possible explanation for the outlier concentrations reported in the August 2018
sample is that the sample was affected by high pH grout, causing concentrations of inorganic
constituents to be biased high.
Well PW-1 also exhibited high concentrations of arsenic. The four samples collected from PW-1
with high arsenic concentrations occurred in the first 5 sampling events after the well was
constructed, possibly indicating that samples were affected by high pH grout in PW-1 as well.
3

Piedmont Lithium Carolinas, Inc. I Technical Memorandum — Evaluation of Mine Pit Operations on Water Quality ���
Data Comparisons
Note that arsenic is a naturally occurring element in bedrock, unconsolidated overburden soils,
groundwater, and surface water within the Piedmont Physiographic Province of North Carolina.
The USEPA has established a standard, called the maximum contaminant level (MCL), for
arsenic in water of less than 10 tag/L for public water systems; however, naturally -occurring
arsenic is present in groundwater throughout North Carolina at concentrations from 1 pg/L to
800 tag/L (NCDEQ, 2021). Thus, the concentrations of arsenic detected during periodic
groundwater monitoring conducted between August 2018 and February 2020 are consistent
with naturally -occurring conditions in North Carolina.
2.1.3.2 FLUORIDE
Fluoride exceedances occurred in groundwater samples from PW-1 and detections occurred it
samples from other monitoring wells (MW-1, MW-4, MW-5, OW-1 S, OW-1 D, OW-2S, and OW-
2D) (Figure 4f). The presence of fluoride indicates that fluoride may be naturally occurring in
bedrock at the Site and mobile in the aquifer. Fluoride occurs naturally in groundwater through
dissolution of fluoride bearing minerals like amphibolite (Kumar, 2017). Alkalinity (high pH) is a
factor for dissolution of fluoride (Kumar, 2017). Groundwater samples from MW-1, MW-3, MW-
4, MW-5, and PW-1 had pH levels above the 2L Standards (range of 6.5 to 8.5). Fluoride was
not detected in the TCLP leachate testing or in surface water at the Site.
2.1.3.3 MANGANESE
The granular material from the TCLP analyses contained iron and manganese at levels above
the Protection of Groundwater PSRGs, but the concentrations are typical of naturally occurring
soils in the Piedmont Physiographic Province (HDR, 2021 a). The concentration of manganese
in the leachate was at an estimated concentration (J-value) but does fall inside the range of
concentrations detected in groundwater samples (Figure 4e).
2.1.3.4 BARIUM
The granular material from the TCLP analyses contained barium at a concentration of 4.8
mg/kg. Barium was detected in the leachate sample at an estimated concentration of 43J tag/L.
The concentration of barium in the TCLP leachate is similar to or an order of magnitude higher
than the concentrations observed in groundwater samples (Figure 4g).
2.2 Surface Water
2.2.1 Surface Water Flow
Surface water flow was measured at 15 locations within the mine permit boundary in May and
June 2019 (Figure 1). Measured stream flow ranged from more than 10,000 gallons per minute
(gpm) to less than 1,000 gpm on larger streams (FM-1 through FM-6) and smaller tributaries
(Weir-1 through Weir-9), respectively (Figure 5). Rainfall occurred prior to and/or during both
measurement periods, thus, neither of the measurement events appear to represent baseflow
conditions.
Dewatering for removal of resource from mine pits intercepts water that would naturally enter
nearby streams and may cause or increase the flow of water from the streams to groundwater.
Groundwater removed from mine pits during dewatering will be discharged to settling ponds
prior to controlled release through permitted outfalls. After release, the water may flow out

Piedmont Lithium Carolinas, Inc. I Technical Memorandum — Evaluation of Mine Pit Operations on Water Quality
Data Comparisons
through streams or wetlands or infiltrate into the groundwater system. The current operations
plan has no more than two pits actively mined simultaneously. Dewatering discharge will be
monitored through National Pollutant Discharge Elimination System (NPDES) permitting and
compliance. Dewatering rates were estimated with groundwater modeling described in the
Technical Memorandum — Groundwater Model (HDR, 2021 b) and are shown in Table 2.
Dewatering rates range from 575 gpm in the first year South Pit is operating to 2,000 gpm in
year 12 when both East and West Pits are being mined.
Table 2. Model Predicted Dewatering Withdrawal Rates (HDR, 2021a)
Pumping Rate (gpm)
Model Year
South Pit
East Pit
50
West Pit North Pit
Total
1
525
575
2
975
1,225
2,300
3
725
775
1,500
4
25'
1,025
1,050
5
751
950
1,025
6-10
N/A2
1,250
1,250
11
N/A2
1,575
1,575
12
N/A2
1,050
950
2,000
13
N/A2
0
500 850
1,350
14-16
N/A2
N/A2
1,0753
1,075
2.2.2 Surface Water Quality
There were no exceedances of NCDEQ surface water standards 15A NCAC 02B (213
Standards) during surface water sampling events between August 2018 and February 2020.
The range of concentrations of constituents in surface water samples are shown in box and
whisker plots (Figures 2a through 4n). Phosphorus, lithium, and manganese concentrations
shown in Figures 4n, 4i, and 4e, respectively, were generally higher during the warm season
(May 2019 through October 2019). Chloride concentrations oscillated with the highest
concentrations occurring in November 2019 (Figure 41). Sulfate concentrations were highest
during the cold months with the highest concentrations occurring in December 2019
(Figure 4m). The highest pH values occurred in June 2019 and the lowest in February 2019
(Figure 4a). Arsenic and fluoride were not detected in any of the surface water samples.
2.3 Comparison of Groundwater and Surface Water Quality
PLCI anticipates pumping groundwater from the mine pits to settling ponds prior to release to
streams through permitted outfalls. Characteristics of the groundwater (dissolved oxygen,
turbidity, pH, temperature, and constituent concentrations) may change depending on the length
of time water is retained in the settling ponds. Thus, comparison of the average and range of
concentrations for selected constituents with detections in both groundwater and surface water
is appropriate to evaluate if groundwater discharge to surface water may affect surface water
quality (Table 3).

Piedmont Lithium Carolinas, Inc. I Technical Memorandum - Evaluation of Mine Pit Operations on Water Quality
Data Comparisons
Table 3. Comparison of groundwater and surface water samples
Average
Maximum
Minimum
Constituent
Groundwater Water Surface
Groundwater Water Surface
Groundwater Surface
Water
Turbidity (NTU)
5.62
9.21
64.60
21.30
0.17
3.04
DO (mg/L)
4.58
10.47
9.09
26.75
0.14
6.23
pH
8.12
7.08
11.97
8.67
5.87
6.17
Temperature (°C)
16.38
14.18
20.50
22.00
12.00
6.10
Manganese
(pg/L)
16.92
46.78
65.50
161.00
5.00
6.50
Lithium (pg/L)
Chloride m /L
229.05
16.73
1370.00
3.30
45.90
5.70
30.50
6.40
1.58
3.70
1.00
2.20
Sulfate (mg/L) 4.65 2.22 19.40 3.90 1.00 1.00
Box and whisker plots comparing constituents that were detected in both groundwater and
surface water samples are shown in Figures 4a through 4n. Comparison of these data indicate
the following:
• Manganese and barium concentrations are typically higher in surface water compared to
concentrations in groundwater (Figure 4e and 4g, respectively). The concentration of
manganese in most groundwater samples is below the 2L Standard. Barium
concentrations are well below the 2L Standard. Discharge of groundwater to steams is
not expected to raise concentrations of manganese or barium in the streams.
• Lithium concentrations are lower in surface water compared to groundwater (Figure 4i).
Discharge of groundwater directly into streams would not raise lithium levels above the
standards. However, dewatering of mine pits will intercept groundwater that would
naturally discharge to streams and may cause or increase water to flow out of the
streambed into the ground.
• Chloride concentrations are similar for both groundwater and surface water and are
below the 2L Standard (Figure 41).
• Sulfate is also present in both the groundwater and surface water at concentrations well
below the 2L Standard. Groundwater has a higher range of concentrations of sulfate
extending both above and below the range of sulfate concentrations in surface water
samples.
• Arsenic, chromium, lead, and fluoride were detected in a few groundwater samples but
were not detected in any surface water samples (Figures 4b, 4c, 4d, and 4f,
respectively). Some groundwater samples exhibited concentrations of arsenic,
chromium, lead, and fluoride above the 2L Standards. Eight out of 120 samples had
detections of arsenic. The number of detections for chromium, lead, and fluoride were
also small relative to the number of samples collected. Groundwater is naturally
discharging to streams on the Site and does not cause elevated levels of these
constituents in the stream water. Discharging groundwater pumped during dewatering is
not likely to raise concentrations of arsenic, chromium, lead, and fluoride in stream
water.
• Cadmium, mercury, and selenium were detected in groundwater samples but were not
detected in any surface water samples (Figures 4h, 4j, and 4k, respectively). Cadmium

Piedmont Lithium Carolinas, Inc. I Technical Memorandum — Evaluation of Mine Pit Operations on Water Quality
Conclusions
concentrations in all groundwater samples were below the 2L Standards. Selenium was
only detected in the one sample collected from MW-5 after well construction (August
2018 event) and is likely not a constituent of concern at the Site. Mercury was only
detected in three groundwater samples during one sampling event and is likely not a
constituent of concern.
• The average pH and the range of values of pH of groundwater samples is higher than
that of the surface water samples.
3 Conclusions
Comparison of groundwater and surface water quantity and quality data, as well as TCLP
testing results, yield the following conclusions regarding potential effects of mine pit operation
on water quantity and quality within the mine permit boundaries:
• Groundwater levels appear to have a seasonal variation with fluctuations ranging up to
10 feet. Groundwater geochemistry also fluctuates and loosely follows a seasonal
pattern.
o Phosphorus, lithium, and manganese concentrations were generally higher
during the warm season (May 2019 through October 2019). Chloride
concentrations oscillated with the highest concentrations occurring in November
2019. Sulfate concentrations were highest during the cold months with the
highest concentrations occurring in December 2019. The highest pH values
occurred in June 2019 and the lowest in February 2019.
• Based on modeled dewatering rates, the maximum decrease in baseflow is predicted to
occur in Beaverdam Creek below the confluence with Little Beaverdam Creek during
dewatering plan years 14 through 20 (end of year 20) when the combined West and
North Pit is being dewatered and groundwater is flowing back into East Pit (HDR,
2021 b).
Groundwater is naturally discharging to streams on the Site and does not cause
elevated levels of naturally -occurring constituents in the stream water. Discharging
groundwater pumped during dewatering is not likely to raise concentrations of arsenic,
chromium, lead, and fluoride in stream water. Comparison of groundwater and surface
water quality indicates the following.
o Discharge of groundwater to steams is not expected to raise concentrations of
manganese, barium, chloride, or sulfate in the streams.
o Lithium concentrations are lower in surface water compared to groundwater.
Discharge of groundwater directly into streams would not raise lithium levels
above the standards. However, dewatering of mine pits intercepts groundwater
that would naturally discharge to streams and may cause or increase water to
flow out of the streambed into the ground.
o Arsenic, chromium, lead, and fluoride were detected in a few groundwater
samples, but were not detected in any surface water samples. Eight out of 120
samples had detections of arsenic. The number of detections for chromium, lead,
and fluoride were also small relative to the number of samples collected.
Discharging groundwater to streams is not likely to raise concentrations of
arsenic, chromium, lead, and fluoride in stream water.

Piedmont Lithium Carolinas, Inc. I Technical Memorandum — Evaluation of Mine Pit Operations on Water Quality
References
PLI plans to dry -stack non -hazardous mine refuse streams of native overburden,
concentrator tails, and analcime tailings and/or use the refuse to backfill mine pits for
reclamation (MMA, 2019). The results of the TCLP analysis indicate that the analcime
tailings do not qualify as toxic hazardous waste (HDR, 2021 a). TCLP testing did not
result in mobilization of arsenic. Precipitation and native groundwater will fill the porous
space around refuse used to backfill mine pits. Native groundwater has a higher pH than
the fluid used in the TCLP analysis. Geochemical reactions may differ from reactions
that occurred in the TCLP analysis.
4 References
HDR, 2019. Technical Memorandum Groundwater Model. Prepared for Piedmont Lithium. July
2, 2019.
HDR, 2020. Technical Memorandum Water Quality Testing. Prepared for Piedmont Lithium.
March 20, 2020.
HDR, 2021 a. Technical Memorandum Toxicity Testing of Lithium Hydroxide Conversion Plant
Tailings. Prepared for Piedmont Lithium Carolinas, Inc. August 26, 2021.
HDR, 2021 b. Technical Memorandum Groundwater Model. Prepared for Piedmont Lithium
Carolinas, Inc. August 27, 2021.
MMA, 2019. Summary of Waste Rock and Process Tailings Geochemical Assessment and
Addendum Report: Result of Humidity Cell Leaching Tests. Prepared for Piedmont Lithium,
Inc. December 2019.
North Carolina Department of Environmental Quality. Arsenic — Naturally occurring Arsenic in
Groundwater. https:Hdeg.nc.gov/about/divisions/energy-mineral-land-resources/north-
carolina-geological-survey/geologic-hazards/radon-arsenic
PJ Sajil Kumar, 2017. Fluoride in Groundwater — Sources, Geochemical Mobilization and
Treatment Options. February 20, 2017.
United States Geologic Survey, 2021. https://www.usgs.gov/mission-areas/water-
resources/science/arsenic-and-drinking-water?qt-science center objects=0#gt-
science center objects

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OVA —
SAMPLE LOCATION MAP
P I E PIEDMONT LITHIUM
LITHIUM FIGURE 1
TECHNICAL MEMORANDUM: WATER QUALITY TESTING

Piedmont Lithium I Technical Memorandum — Toxicity Testing ���
Figures.
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750
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_
= 744
c
C7
742
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's
ii~(°
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756
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754
= 752
0
} 750
LU
L 748
3 746
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744
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742
e
bti
O, Q� Q0
PIEDMONT
LITHIUM
F)I
Groundwater Elevations
DA7E
August 2021
FICAA;E
Figure 2b

PLI Groundwater Monitoring Wells (Bedrock)
c;40
Median
1
1 %,
ff CC
L511/6,7.] %
9%-91 %
}�
V outliers
so U
780
760
Elm
l)'i•;-ID O -2D IYIYV-1 IYIYV-C M V-J IYIYV-4 M V-5
Groundwater Elevation
� � Box and Whisker of Groundwater Elevations in August 2021
PIEDP►Ntlwiv F)I the Bedrock Wells Figure 3a

PLI Groundwater Monitoring Wells (Overburden)
755
— Median
9%-91 %
D outliers
750
Q
,4 r
A
V
40
ow -IS OW-2S
Groundwater Elevation
�� Box and Whisker of Groundwater Elevations in August 2021
PIEDP►INIU F)I the Overburden Wells Figure 3b

12
10
c 9
7
5
5
pH in Groundwater and Surface Water
I 0 0
o o �
T T G +
T I 0 T
I 1 1 I 1 1 I I T T
I 1 1 I 1 1 I I 4 I
1 I 1 I T
FI FI FI I
1 I 1 I I I I
1 I 1 i I I I
1 I 1 I I I I
1 I I I I
+ + +
+ +
0 I
Groundwater
Surface Water
Aug Apr Jun Jul Aug Sept Oct Nov Dec Jan Feb Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec Jan
201E 2019 2019 2019 2019 2019 2019 2019 2019 2020 2020 2019 2019 2019 2019 2019 2019 2019 2019 2019 2019 2019 2020
Date
PIEDMONT
►Ntl IUM
F)R
Box and Whisker of pH Levels in All Wells or All
Stream Sampling Locations for Each Sampling Event
J Median
T !�
5 °14-75 %
9%-91 %
O outliers
NDAD Standard
August 2021
Figure 4a

103
102
10°
Arsenic Concentration in Groundwater and Surface Water
MW-5 Groundwater
T
I
I
I
I
I T
I I O
I + + I
x x x x x x x x x x
Surface Water
Arsenic was not detected in any surface water samples.
Aug Mar Apr Jun Jul Aug Sept act Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec Jan
2018 2019 2019 2019 2019 2019 2019 2019 2019 2019 2020 2020 2019 2019 2019 2019 2019 2019 2019 2019 2019 2019 2020
Date
PIEANT
►NtHIUM
F)I
Box and Whisker of Arsenic Concentration in All
Wells or All Stream Sampling Locations for Each
Sampling Event
Median
+
I]},
ff ff
%-91 %
outliers
X
TCLP
NCAC Standard
August 2021
Figure 4b

U
1os
102
10'
100
MW-5
Groundwater
Chromium Concentration in Groundwater and Surface Water
Surface Water
Chromium was not detected in any surface water samples.
Aug Mar Apr Jun Jul Aug Sept Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec Jan
2018 2019 2019 2019 2019 2019 2019 2019 2019 2019 2020 2020 2019 2019 2D19 2019 2019 2019 2D19 2019 2019 2019 2020
Date
PIEDMONT
►Ntl IUM
F)I
Box and Whisker of Chromium Concentration in All
Wells or All Stream Sampling Locations for Each
Sampling Event
Median
25 °14-75 %
9%-91 %
outliers
— NOAO Standard
August 2021
Figure 4c

4(1
020i
0
ivi vv-.-)
l
1
1
1
1
Groundwater
Lead Concentration in Groundwater and Surface Water
X
Surface Water
Lead was not detected in any surface water samples.
Aug Mar Apr Jun Jul Aug Sept Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec Jan
2018 2019 2019 2019 2019 2019 2019 2019 2019 2019 2020 2020 2019 2019 2019 2019 2019 2019 2019 2019 2019 2019 2020
Date
Median
+ it,
5 °10-75 %
9%-91 %
outliers
NCAC Standard
DATE
Box and Whisker of Lead Concentration in All Wells August 2021
PIEDMONT FDIor All Stream Sampling Locations for Each Sampling F'
LITHIUM Figure 4d
Event

Manganese Concentration in Groundwater and Surface Water
180
i
I
160
Groundwater
�
Surface Water
—
Median
+ it,
5'/o--75 %
10
L
outliers
X TDLP
— NOAO Standard
120
L
L
D
4
�
T
J
100
L
I
I 0
L
!
I
1
g0
L
L
!
!
I 1
I 1
—
0
L
!
I 1
O
0
!
!
I 1
1 1
0
60
L
�
T
0 I
I
O
I
+
I
I
+
1
1
40
T
0
I
0
I
4- 4—
0
I
I T
I
1
20
I
I
+
F IF-
I 0+
1
I-V7
H0
F
x
F
F i
=
-4�-j
Mar
Apr
Jun
Jul Aug Sept
Oct Nov
Dec Jan Feb Mar
Apr May
Jun
Jul
Aug
Sept Oct
Nov
Dec Jan
2D19
2D19
2019
2019 2019 2019
2019 2019
2019 2020 202D 2019
2019 2019
2019
2019
2019
2019 2019
2019
2019 2020
Date
PIEDMONT
LITHIUM
F)2
DA7E
Box and Whisker of Manganese Concentration in All August 2021
Wells or All Stream Sampling Locations for Each FIU'`
Figure 4e
Sampling Event

U
2._
0.5
0
Fluoride Concentration in Groundwater and Surface Water
O
Groundwater
❑ ❑
G O O
O
r
I
T 1
I I I T 1 I T
I I I 1 I I T I
I I I 1 I I I I
I I I 1 I I I I
T I I I 1 I I I I
1 1
1 1 i i 1 I I I
+ f f f
1 I I I I
Surface Water
Fluoride was not detected in any surface water samples.
Aug Mar Apr Jun Jul Aug Sept Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec Jan
201E 2019 2019 2019 2019 2019 2019 2019 2019 2019 2020 2020 2019 2019 2019 2019 2019 2019 2019 2019 2019 2019 2020
Date
PIEDMONT
►Ntl IUM
F)3
Median
T �f
25 %- 75 %
9%-91 %
outliers
NOAO Standard
Box and Whisker of Fluoride Concentration in All August 2021
Wells or All Stream Sampling Locations for Each Figure 4f
Sampling Event

Barium Concentration in Groundwater and Surface Water
10
MW-5
Groundwater
Surface Water
Median
r �f
i
5%-75%
i
9%-91%
i
O
Q outliers
TLP
NCAC Standard
10
i
i
_
J
`ax
!
i
3
i
i
c
! p o O
10
i i
+ +
i I0
4— 4-
+ + + +
10�
Aug Mar Apr Jun Jul Aug
Sept Cct Nov Dec Jan
Feb Mar Apr May Jun
Jul Aug
Sept Cc[ Nov
Dec Jan
2018 2019 2019 2019 2019 2019
2019 2019 2019 2019 2020
2020 2019 2019 2019 2019
2019 2019
2019 2019 2019
2019 2020
Date
Box and Whisker of Barium Concentration in All August 2021
PIEDPAONT 1NIMr���t F)3 Wells or All Stream Sampling Locations for Each Figure 4g
Sampling Event

Cadmium Concentration in Groundwater and Surface Water
2
Median
Groundwater
Surface Water
+ it,
51/o--75 %
9%-91 %
outliers
NCAC Standard
J
MW-5
�
0
p
c
0
T
I
I
I
Cadmium was not detected in any surface water samples.
I
I
I
0,
Aug Mar Apr Jun Jul Aug Septr Oct Nov Dec Jan Feb
Mar Apr May Jun Jul Aug Sept Oct Nov Dec Jan
2018 2019 2019 2019 2019 2019 2019 2019 2019 2019 2020 2020
2019 2019 2019 2019 2019 2019 2019 2019 2019 2019 2020
Date
PIEDMONT
LITHIUM
F)I
DA7E
Box and Whisker of Cadmium Concentration in All August 2021
Wells or All Stream Sampling Locations for Each F'
Figure 4h
Sampling Event

Lithium Concentration in Groundwater and Surface Water
gn
1Qs
D
0
0 0
T
T
I
I
!
TI
I
I
T
I
i
I I
I I
I
I
i
!
! I
Surface Water
I
I
I
I I
I
! I
—Median
I
I
! I
I
I I
I
I
! I
T {r
I
I
!
I
II I
I
I
I I
5%-75%
I
+
I [
I
! !0
outliers
J
�7
C
D 102
c
I
I
I
I
G
O
p
O
O
Q
D
O O
0
D
T
I
T
I
0
I 0
D
O
G.
!
i I
I
]
! T
Q
a
Groundwater
1
�
I
!
I
I
1
�
101
Mar
Apr
Jun Jul
Aug
Sept Oct
Nav
Dec
Jan Feb
Mar
Apr
May
Jun
Jul Aug
Sept
Oct
Nav Dec
Jan
2019
2019
2019 2019
2019
2019 2019
2019
2019
2020 2020
2019
2019
2019
2019
2019 2019
2019
2019
2019 2019
2020
Date
Box and Whisker of Lithium Concentration in All August 2021
PIEDMONT
Wells or All Stream Sampling Locations for Each FIG_=
111CM1i1�1 Figure 4i
Sampling Event

0.35
0.3
L 0.25
@N
0.15
0.1
Mercury Concentration in Groundwater and Surface Water
0
Groundwater
Surface Water
Mercury was not detected in any surface water samples.
Apr Jun Aug Sept Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sept Oct Dec Jan
2019 2019 2019 2019 2019 2019 2019 2020 2020 2019 2019 2019 2019 2019 2019 2019 2019 2019 2020
Date
PIEDMONT
LITHIUM FDI
Box and Whisker of Mercury Concentration in All
Wells or All Stream Sampling Locations for Each
Sampling Event
Median
+ !L
25 °10-75 %
9%-91 %
outliers
DA7E
August 2021
FICAA;E
Figure 4j

30
25
J 20
U 15
10
Selenium Concentration in Groundwater and Surface Water
MW-5
Groundwater Surface Water
T
I
I
I
I
I
I
I
Selenium was not detected in any surface water samples.
I
I
I
I
I
Aug Mar Apr Jun Jul Aug Sept Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec Jan
2018 2019 2019 2019 2019 2019 2019 2019 2019 2019 2020 2020 2019 2019 2019 2019 2019 2019 2019 2019 2019 2019 2020
Date
PIEDMONT
►NtHIUM
F)I
Box and Whisker of Selenium Concentration in
All Wells or All Stream Sampling Locations for
Each Sampling Event
Median
+ IL
25 °1�-75 %
9%-91 %
outliers
NCAC Standard
August 2021
Figure 4k

Chloride Concentration in Groundwater and Surface water
10
Median
Groundwater
Surface
Water
+ ff
5%-75%
%-91 %
outliers
NOAO Standard
10`
J
E
C
D
C
0
C
f_7
101
Q•
I
10 �L
1
I R f 1
11 1- 1
-1
Aug Mar Apr Jun Jul Aug Sept Oct Nov Dec Jan Feb
Mar Apr May Jun Jul Aug Sept Oct Nov Dec Jan
2018 2019
2019 2019 2019 2019 2019
2019 2019 2019 2020 2020
2019 2019
2019 2019
2019
2019 2019 2019 2019 2019 2020
Date
Box and Whisker of Chloride Concentration in All August 2021
PIEDMONT 111rIMri�1 Wells or All Stream Sampling Locations for Each Figure 41
Sampling Event

Sulfate Concentration in Groundwater and Surface Water
Median
Groundwater
Surface Water
+ !],
5 %
A51/1w-.7
7%-9 1 1 %
outliers
NCAC Standard
102
J
E
-
/ MW-5
c
0
0
U
101
1 D
0
0 O
T
Q
T
1
Q
0
+
1
+
,
+
1
I
1
1
+
+
+ +
+
+
I
I
+
1
1
I
1
17
+
1
0
0
G
1
100
1
I
I
1
1
Aug Mar Apr Jun Jul Aug Sept Oct Nov Dec Jan Feb
Mar Apr May Jun Jul Aug Sept Oct Nov Dec Jan
2015 2019 2019
2019
2019 2019 2019
2019
2019
2019
2020
2020
2019
2019
2019
2019
2019 2019 2019
2019 2019
2019
2020
Date
PIED�� Box and Whisker of Sulfate Concentration in All August 2021
111rIMri�1 Wells or All Stream Sampling Locations for Each Figure 4m
Sampling Event

Phosphorus Concentration in Surface Water
CIA G
O
T
I
I
Median
'-' ..I 4
I
+ pt
9%-91 %
outliers
c.I2
J
E
0.1
c
0
C
O
c
cD
4.48
I
0
I
4.46
I
I
I
I
-
I
T
+ I
I
I
1
0.44
I
I
I
I
+ 1
Q
Q O
0
0
0.02
February March April May
June July August September
October
November December January
2019 2D19 2D19 2419
2019 2019 2019 2019
2019
2019 2019 2020
Date
PIEDMONT
►Ntl IUM
F)l
Box and Whisker of Surface Water Quality Data
August 2021
Figure 4n

12000
10000
8000
CL° 6000
: 4000
2000
0
(a)
Measured Surface Water Flow
1111111- -- 11 - -- - - --
■ 5f 15f2019 - 5/15/2019 0 6/11/2019 - 6f 15f2019
PIEDMONT
►IT"JUM
F)I
12,000
10, 000
8,000
CL
° 6,000
0
,i 4,000
(b)
2,000
0
Model Predicted Baseflovwr in Streams
IIIIIIII
Steady 1 2 3 4 5
State Model Year
6-10 11 12 13 14-20
■ Beaverdarn Creek above Confluence ■ Little Beaverdam Creek
■ Beaverdam Creek Below Confluence ■ Unnamed Tributary
Measured and Modeled Stream Flow
August 2021
Figure 5

Piedmont Lithium I Technical Memorandum — Toxicity Testing ���
Figures.
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