Appendix D Hydrogeology Study and Groundwater Modeling

Technical Report
2022 Prefeasibility Study
Hydrogeological Study and Groundwater
Modeling
Kings Mountain Mining Project
Rev05
Report Date: April 5, 2024
Report Prepared for
ALBEMARLE"
Albemarle Corporation
4250 Congress Street,
Charlotte, NC 28209
Report Prepared by
srk consulting
SRK Consulting (U.S.), Inc.
999 171h Street, Suite 400
Denver, CO 80202
SRK Project Number: USPR000576
Albemarle Document Number : KM60-EN-RP-9044
Authored by:
Audrey Crockett, MSc
Lukas Radmann, BSc Geology, BSc Hydrogeology
Carolyn D. Lambert, M.S., P.G.
Philine Tullius, PhD
Reviewed by:
Goktug Evin, BSc Eng, C.P.G., SME-RM
Vladimir Ugorets, PhD, MMSAQP
Assaf Wunsch, PhD

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Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page ii
Executive Summary
The principal objective of the groundwater study conducted for the Kings Mountain project is to acquire
sufficient hydrogeological and hydrological data to develop predictive tools (numerical models) in
support of ongoing engineering design (PFS) and permitting. More specifically, the numerical
modelling objectives related to the groundwater study are:
• Estimate groundwater inflows to the open pit(PFS).
• Propose a dewatering strategy for the open pit operation (PFS).
• Provide input to the site water balance (PFS, permitting).
• Evaluate post closure pit lake hydrogeology and provide input to the geochemistry team
for pit lake water quality predictions (PFS, permitting).
• Evaluate estimated impacts to groundwater levels and stream flows (permitting).
• Estimate the impact of drawdown on adjacent groundwater users (permitting).
• Determine flow paths and capture zones during maximum mine development(permitting).
• Determine flow paths from TSFs and WRDs to provide input to geochemical fate and
transport evaluations (permitting).
Extensive hydrogeological field investigations were performed at the site in support of the groundwater
study. The field investigations commenced in 2018, coinciding with the exploration drilling campaign.
The exploration drilling campaign was not specifically designed for collection of hydrogeological data,
and therefore hydrogeological data were derived from this campaign when possible. Overtime, drilling
and testing campaigns were designed specifically for hydrogeological data collection. The objectives
of these field studies were as follows:
• Identify major hydrogeological units and estimate their hydraulic parameters (mainly
transmissivity and hydraulic conductivity),
• Understand water levels within the groundwater system, including temporal trends,
groundwater flow direction, and variability of vertical hydraulic gradients with depth,
• Establish a water level database, focusing on understanding pit lake hydrology during the
infilling process.
Between 2018 and 2023, a total of 104 drillholes were used for hydrogeological data collection, with
combined total length drilled of 46,280 ft. The drilling campaigns for hydrogeologic characterization
were overseen by SRK hydrogeologists. Drilling methods included 35 diamond coreholes,10 rotary
boreholes, and 45 sonic boreholes.A total of 124 hydraulic tests were completed in various boreholes,
including: 26 packer tests, 51 slug tests, 15 short-term pumping tests, 7 long-term pumping tests; and
25 wells were spinner logged. Additional field work included the installation of a comprehensive
monitoring system to measure water levels and water level trends, pit lake levels and stream flows.
An inventory of seeps,springs, and groundwater wells was established. Collected field data were used
to develop conceptual hydrogeological models and numerical groundwater flow models.
SRK developed a conceptual hydrogeological model that identified major hydrogeological units and
associated hydraulic parameters, major faults and their hydrogeological role, mechanisms of
groundwater recharge and discharge, water levels and direction of groundwater flow, and potential
changes to current hydrogeological conditions due to proposed mining and subsequent post-mining
conditions. This conceptual model was developed based on mine-scale and regional-scale Leapfrog
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Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page iii
geological models (the regional model was specifically developed to support the numerical
groundwater model).
SRK developed the numerical groundwater model for the Kings Mountain project using the
MODFLOW-USG control-volume finite-difference simulator. The numerical model used an
unstructured grid formulation with Voronoi polygons and was designed to estimate groundwater inflow
to the proposed open pit, pit lake recovery following mining operation,water level changes and impact
to the groundwater system during proposed mining and post-mining conditions. The numerical model
incorporated 13 major hydrogeological units that were identified in the geological model (further
subdivided to 32 hydrogeological units) and simulated recharge from precipitation and proposed
mining facilities, interaction with surface-water bodies, excavation of the pits and pit lakes infilling (both
historical and proposed).
SRK calibrated the numerical model to historical inflows and pit lake water levels, baseflow estimates
in creeks and groundwater levels (including responses to long-term pumping tests). According to
SRK's assessment, the model effectively replicated both past and present conditions. Calibration to
groundwater levels resulted in a normalized root mean square of less than 10%. Simulated deviations
from measured baseflows ranged from 1% to 5%. These error rates are considered acceptable when
compared to industry standards.
The calibrated numerical model was used to predict changes to hydrological conditions, including
inflow to the proposed pit and the propagation of drawdown. The model was also used to assess the
saturation of the proposed backfill, infilling of the post-mining pit lake, and outflow from the pit lake into
the groundwater system. Furthermore, the model was used to evaluate potential spillover of the pit
lake into nearby surface-water bodies, analyzed maximum drawdown propagation, and evaluated the
impact to groundwater users in nearby community wells, springs, and wetlands.
The model predicted under calibrated Base Case:
• Groundwater inflow rates to the proposed pit in the range of 100 to 270 gpm.
• Maximum 5-ft drawdown extent of 0.29 miles to the southeast, 0.52-0.53 miles to the
northwest and northeast, and 1.22 miles to the southwest. The maximum drawdown extent in
various directions will occur at different times, from approximately 11 to 30 years after end of
mining.
• Maximum reduction in baseflow in Kings Creek within the model domain of 88 gpm (or 1.4%).
Maximum reduction will occur 18 years after end of mining. The model did not predict any
changes to baseflow in Long Creek.
• Saturation of partial backfill placed in the proposed pit, with backfill top elevation of 570 ft
above mean sea level (amsl), in approximately 3 years post-mining.
• The elevation of the pit lake surface will rise until it will reach a spillover elevation of 850 ft
amsl approximately 56 years post-mining.
• Groundwater inflow to the pit lake is anticipated to gradually decrease over time. The initial
groundwater inflow rate of 270 gpm, at the end of mining operations, is expected to decline
and stabilize at approximately 63 gpm after 68 years of recovery.
• The pit lake will begin to outflow to the groundwater system after approximately 46 years of
lake infilling, predominantly in the southeast direction of the pit lake. The outflow rate was
projected to gradually increase over time and reach approximately 27 gpm.
• The pit lake spillover rate to downstream surface water drainages was estimated at 198 gpm.
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Sensitivity analysis indicated that:
• The model predictions are most sensitive to the storage parameters (specific yield) of the
surrounding rock, the hydraulic conductivity of the shear zone, and to the existence and
transmissivity of a potential transition zone and a fault.
• Maximum passive inflows to the pit ranged from 228 to 336 gpm; passive inflows to the pit at
end of mining ranged from 228 to 334 gpm.
• Time to reach the pit lake spillover elevation after mining ranged from 49 to 64 years post
mining.
• The maximum extent of the 5-ft drawdown contour ranged from 0.50 to 0.61 miles in the
northwest direction, 1.18 to 1.26 miles in the southwest direction, 0.52 to 1.23 miles in the
northeast direction, and 0.28 to 0.30 miles in the southeast direction.
• The maximum reduction in flow to Kings Creek ranged from 59 to 88 gpm.
In summary, the completed hydrogeological study successfully employed geological data, field
investigations, and the development of a 3-D numerical groundwater model to comprehensively
understand and predict the interactions between mining activities and the groundwater system. The
findings of this study will provide crucial information for effective management and mitigation of
potential impacts to the groundwater system, ensuring sustainable mining practices and the protection
of water resources and associated ecosystems.
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Table of Contents
1 Introduction.................................................................................................................. 1
1.1 Mining History .....................................................................................................................................2
1.2 Existing Site Layout.............................................................................................................................3
1.3 Summary of Proposed Project Layout and Mine Plan........................................................................4
1.4 Objectives of Groundwater Study.......................................................................................................8
1.5 Report Structure..................................................................................................................................8
2 General Setting, Climate, and Geology...................................................................... 9
2.1 Topography and Geomorphology.......................................................................................................9
2.2 Climate..............................................................................................................................................10
2.3 Surface Water Resources and Pit Lake............................................................................................11
2.4 Geological Setting.............................................................................................................................13
2.4.1 Regional Geology..................................................................................................................13
2.4.2 Kings Mountain Deposit ........................................................................................................15
2.4.3 General Lithological Sequence .............................................................................................16
2.5 Deposit Structural Geology...............................................................................................................17
2.6 Leapfrog Geological Model...............................................................................................................18
2.6.1 Local Geological Model.........................................................................................................18
2.6.2 Regional Geological Model ...................................................................................................20
3 Summary of Field Investigations.............................................................................. 22
3.1 Drilling 22
3.2 Hydraulic Tests .................................................................................................................................24
3.3 Water Level Monitoring.....................................................................................................................26
3.4 Surface Water Monitoring and Baseflow Analyses...........................................................................29
3.4.1 Continuous Streamflow Monitoring .......................................................................................29
3.4.2 Baseflow Estimates...............................................................................................................31
3.4.3 Pit Lake Water Level Monitoring ...........................................................................................31
3.5 Seep and Spring Survey...................................................................................................................34
3.6 Groundwater Well Inventory Survey.................................................................................................36
4 Conceptual Hydrogeological Model ......................................................................... 38
4.1 Hydrogeological Units.......................................................................................................................40
4.1.1 Regolith .................................................................................................................................40
4.1.2 Bedrock .................................................................................................................................40
4.2 Hydrogeological Significance of Major Faults...................................................................................41
4.3 Hydraulic Conductivity and Transmissivity Values ...........................................................................41
4.4 Groundwater Storage........................................................................................................................46
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4.5 Heterogeneity and Anisotropy...........................................................................................................46
4.6 Recharge - Discharge.......................................................................................................................47
4.7 Groundwater Flow and Water Levels................................................................................................47
4.8 Conceptual Mine Development and Post-Mining Conditions ...........................................................51
5 Numerical Groundwater-Flow Modeling .................................................................. 53
5.1 Grid Discretization and Physical Model Boundaries.........................................................................54
5.2 Simulation of Hydrogeological Features...........................................................................................59
5.2.1 Simulation of Hydrogeological Units .....................................................................................59
5.2.2 Simulation of Recharge to Groundwater System..................................................................66
5.2.3 Simulation of Groundwater Discharge into Surface Water Bodies .......................................68
5.2.4 Simulation of Historic Mining.................................................................................................70
5.2.5 Simulation of Pit Lake Recovery...........................................................................................71
5.3 Measured Water Levels and Pit Inflow and Transient Model Calibration.........................................73
5.3.1 Calibration to Historical Pit Lake Inflow and Water Levels....................................................73
5.3.2 Calibration to Baseflow..........................................................................................................76
5.3.3 Calibration to Current Groundwater Levels...........................................................................77
5.3.4 Summary of Model Calibration, Simulated Water Table and Groundwater Budget..............81
5.4 Simulation of Proposed Open Pit......................................................................................................81
5.5 Simulation of Partial Pit Backfilling....................................................................................................82
5.6 Simulation of Proposed Pit Lake Infilling...........................................................................................83
6 Predictions of Future Mining .................................................................................... 85
6.1 Predicted Passive Inflow to Open Pit................................................................................................85
6.2 Predicted Water Table and Its Changes...........................................................................................85
6.3 Predicted Change in Groundwater Budget.......................................................................................86
7 Predictions of Post-Mining Conditions.................................................................... 91
7.1 Predicted Pit Lake Infilling.................................................................................................................91
7.2 Predicted Water Level Changes.......................................................................................................91
7.3 Predicted Changes in Groundwater Budget.....................................................................................92
7.4 Predicted Changes in Baseflow........................................................................................................92
7.5 Predicted Pit Lake Water Balance Components as Input for Pit Lake Chemistry Modeling ............93
7.6 Predicted Impacts to Water Resources ............................................................................................99
8 Hydrogeological Uncertainties and Results of Sensitivity Analysis ................... 101
8.1 Uncertainties in Understanding Hydrogeological Conditions and Purpose of Sensitivity Analysis 101
8.2 Results of Sensitivity Analysis of Passive Pit Inflow.......................................................................102
8.3 Results of Sensitivity Analysis of Maximum Drawdown Extent ......................................................103
8.4 Sensitivity Analysis of Pit Lake Infilling and Spillover Outflow........................................................104
8.5 Sensitivity Analysis of Reduction of Groundwater Inflow to the Creeks .........................................105
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8.6 Climate Section Evaluation for Long Term Closure Predictions.....................................................109
8.7 Simulation of Martin Marietta Pit and Its Potential impact Predictions ...........................................109
9 Conclusions ............................................................................................................. 110
10 References................................................................................................................ 112
Disclaimer...................................................................................................................... 113
Copyright ....................................................................................................................... 113
List of Tables
Table 2-1: Geological Model Units ...................................................................................................................16
Table 3-1: Baseflow Estimates for Kings Creek and South Creek...................................................................31
Table 4-1: Summary of Hydraulic Testing of Hydrogeological Units................................................................43
Table 5-1: Hydraulic Properties Used in Numerical Groundwater Model.........................................................60
Table 5-2: Comparison of the Modeled and Measured Values of Hydraulic Conductivity...............................61
Table 5-3: Comparison of Measured and Simulated Baseflows ......................................................................77
Table 5-4: Statistics of Model Calibration to Measured Water Levels..............................................................84
Table 6-1: Predicted Groundwater Budget for End of Mining...........................................................................90
Table 7-1: Predicted Water Balance of Future Pit Lake for Long-term Post-Mining Conditions......................91
Table 7-2: Predicted Groundwater Budget for Long-term Post-Mining Conditions..........................................99
Table 8-1: Results of Sensitivity Analysis of Predicted Pit Inflow...................................................................103
Table 8-2: Results of Sensitivity Analysis of Maximum Water Table Drawdown Extent................................104
Table 8-3: Results of Sensitivity Analysis of Time of Pit Lake Infilling ...........................................................105
Table 8-4: Results of Sensitivity Analysis of Kings Creek Baseflow Reduction.............................................106
List of Figures
Figure 1-1: Project Location Map .......................................................................................................................2
Figure 1-2: Previous Operation and Existing Site Layout...................................................................................4
Figure 1-3: Proposed Mine Plan.........................................................................................................................5
Figure 1-4: Planned Open Pit Development.......................................................................................................7
Figure 2-1: Project Area Topography...............................................................................................................10
Figure 2-2: Annual Precipitation .......................................................................................................................11
Figure 2-3: Surface Water Features Around the Mine Site..............................................................................12
Figure2-4: Property Geology Map ...................................................................................................................14
Figure2-5: Stratigraphic Column......................................................................................................................15
Figure 2-6: Location of Fault EW-01 and Associated Lithological Displacement.............................................18
Figure 2-7: Geologic Model Plan View.............................................................................................................19
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Figure 2-8: Geologic Model Cross-Sectional View...........................................................................................20
Figure 3-1: Location of Drilled Boreholes for the Hydrogeological Study.........................................................23
Figure 3-2: Location of Completed Hydraulic Tests .........................................................................................25
Figure 3-3: Location of Monitoring Wells/Points...............................................................................................27
Figure 3-4: Combined Location of Drillholes, Hydraulic Tests, and Monitoring Wells/Points ..........................28
Figure 3-5: Locations for Surface Water Measurements..................................................................................30
Figure 3-6: Pit Lake Recovery Hydrograph ......................................................................................................32
Figure 3-7: Pit Lake Elevation and Barometric Pressure Monitoring Locations...............................................33
Figure 3-8: Seep and Spring Locations............................................................................................................35
Figure 3-9: Groundwater Inventory Map...........................................................................................................37
Figure 4-1: Conceptual Hydrogeological Model of Kings Mountain Pit Area ...................................................39
Figure 4-2: Map of Transmissivity Estimated by Pumping Tests .....................................................................42
Figure 4-3: Distribution of Measured Hydraulic Conductivity Values per Depth for Individual Units................44
Figure 4-4: Distribution of Hydraulic Conductivity Using Spinner Log Evaluation............................................45
Figure 4-5: Map Showing Water Levels and Distribution of Groundwater Flow...............................................48
Figure 4-6: Vertical Hydraulic Gradient Measured in Proximity of Pit Lake .....................................................50
Figure 4-7: Conceptual Model of Groundwater Conditions during Mine Development and Post-Mining.........52
Figure 5-1: Structure of Groundwater Modeling for the Kings Mountain Project..............................................54
Figure 5-2: Plan View of Model Domain and Location of Simulated Surface Water Bodies............................56
Figure 5-3: 3D View of Model Grid ...................................................................................................................57
Figure 5-4: Simulated Boundary Conditions.....................................................................................................58
Figure 5-5: Simulated Bedrock Hydrogeologic Units in Layer 5.......................................................................62
Figure 5-6: Simulated Hydrogeologic Units in Cross-Section A-A....................................................................63
Figure 5-7: Simulated Hydrogeologic Units in Cross Section B-B....................................................................64
Figure 5-8: Comparison of Simulated vs. Leapfrog Cross-Sections ................................................................65
Figure 5-9: Simulated Recharge Zones............................................................................................................67
Figure 5-10: Simulated Recharge Zones Representing Mine Facilities...........................................................68
Figure 5-11: Simulation of Historic Pit Excavation ...........................................................................................70
Figure 5-12: Conceptual Model for Historical (a) and Proposed (b) Kings Mountain Pit Lake.........................72
Figure 5-13: Simulated Stage/Volume (a) and Stage/Area (b) Relationships for the Historical Pit Lake.........73
Figure 5-14: Simulated Inflow to Historical Open Pit........................................................................................74
Figure 5-15: Comparison of Simulated versus Measured Historic Pit Lake Elevation.....................................75
Figure 5-16: Comparison of Groundwater Inflow into Historical Pit Lake Simulated by Groundwater and Surface
WaterModels.......................................................................................................................................76
Figure 5-17: Comparison of Simulated versus Measured Water Levels by Quality Line.................................78
Figure 5-18: Distribution of Water Level Residuals for Simulation of Current Conditions................................79
Figure 5-19: Model Calibration of KMMW-002 Pumping Test..........................................................................80
Figure 5-20: Model Calibration of RTKM22-382 Pumping Test.......................................................................81
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Figure 5-21: Locations of Drain Polygons and Simulated Proposed Pit Bottom Elevation Through Time ......82
Figure 5-22: Simulated StageNolume (a) and Stage/Area (b) Relationship for the Proposed Pit Lake..........84
Figure 6-1: Predicted Groundwater Inflow into Proposed Pit...........................................................................87
Figure 6-2: Predicted Water Table and Direction of Groundwater Flow at End of Mining ...............................88
Figure 6-3: Predicted Water Table Changes at End of Mining Compared to Current Conditions....................89
Figure 7-1: Predicted Future Pit Lake Elevation and Components of Pit Lake Water Balance in Time ..........93
Figure 7-2: Predicted Maximum 5-ft Drawdown Extent....................................................................................94
Figure 7-3: Hydrographs of Water Table Change at Monitoring Points Shown in Figure 7-2..........................95
Figure 7-4: Predicted Water Table and Direction of Groundwater Flow for Long-Term Post-Mining Conditions
.............................................................................................................................................................96
Figure 7-5: Predicted Water Table Changes for Long-Term Post-Mining Compared to Current Conditions...97
Figure 7-6: Predicted Baseflow in Kings Creek, Long Creek, and South Creek during Mining and Post-Mining
Conditions............................................................................................................................................98
Figure 8-1: Results of Sensitivity Analysis of Passive Pit Inflow....................................................................106
Figure 8-2: Results of Sensitivity Analysis of Maximum Drawdown Extent ...................................................107
Figure 8-3: Results of Sensitivity Analysis of Pit Lake Infilling and Spillover Outflow....................................108
Figure 8-4: Results of Sensitivity Analysis of Reduction of Groundwater Inflow to the Creeks .....................109
Appendices
Appendix A: Hydrogeological Units per Model Layers
Appendix B: Comparison of Simulated and Measured Water Levels
Appendix C: Components of Pit Lake Balance as Input for Pit Lake Chemistry Modeling
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1 Introduction
Kings Mountain Mining Project (KMMP or Project) is a historical open pit operation located in
southwestern North Carolina, USA, adjacent to the city of Kings Mountain on the 1-85 transit corridor,
approximately 33 miles(mi)west of the city of Charlotte (Figure 1-1). The project is a lithium pegmatite
deposit that is currently being explored by Albemarle Corporation (Albemarle). Albemarle
commissioned SRK Consulting (U.S.), Inc. (SRK)to conduct hydrogeological characterization studies
and to develop conceptual and numerical models to support ongoing engineering studies and
permitting efforts to reactivate the project.
The groundwater studies will support Albemarle's engineering study by determining mine inflow rates
and water supply potential of the groundwater system at the project area, as well as providing input to
geotechnical studies. The numerical groundwater model (NGWM) is also planned to be used to inform
closure planning.
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1.1 Mining History
This section provides the Project history, compiled from historical publications and Albemarle
corporate records. In summary:
• Mining at KMMP started in 1883 with the discovery of cassiterite, a tin-bearing mineral, within
the outcropping pegmatites.
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• Subsequently, open-pit mining for tin occurred sporadically between 1903 and 1937 (Horton
and Butler, 1981).
• Between 1943 and 1945, under the sponsorship of the US government, Solvay established a
processing plant and mined for spodumene from the outcropping pegmatites at Kings
Mountain (Garrett, 2004).
• In the early 1950s, Foote, a subsidiary of Newmont Mining Corporation, purchased the
property and began open pit mining (assumed at the beginning of 1955)and extracting lithium
from the spodumene.
• In 1993, exploration and mining operation ceased, by which time the open pit bottom reached
approximately 660 feet (ft) above mean sea level (amsl).
• In early 1994, an open pit lake started to form from groundwater and surface water inflow; pit
lake levels rose since, eventually reaching the current elevation of 817 ft amsl (January 2023).
• During the pit lake recovery period, water was sporadically pumped from the Kings Mountain
Pit lake to the nearby Martin Marietta quarry to support quarry operations.
• In 2015, Albemarle acquired the site and initiated the current exploration and mine
development activities.
1.2 Existing Site Layout
Albemarle has active facilities on the site that include the Global Technical Center and lithium
hydroxide plant. Figure 1-2 shows the current facilities and key landmarks. The Project is bisected
northeast to southwest by Interstate 85. The headwaters of Kings Creek are located immediately
northeast of the site and the creek leaves the Project area at the southern side of the Project area.
The mineral resource and pit lake is located to the north of the existing facilities. Legacy mine waste
facilities are scattered around the project site. The three main legacy facilities are:
• Cardiac hill waste rock dump (WRD), to the north of the existing open pit lake
• Old Mill Tailing (mineral tailings pond)to the south of the hydroxide plant
• Tailings facility located south of highway 1-85
Martin Marietta operates a quarry adjacent to Albemarle's property. The quarry is partially used as a
water supply pond for their operation.Three other man-made surface water ponds are Executive Lake
(located on top of legacy tailings storage facility(TSF)), South Creek reservoir, and #1 Pond.
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Figure 1-2: Previous Operation and Existing Site Layout
1.3 Summary of Proposed Project Layout and Mine Plan
The Project layout is presented in Figure 1-3, showing the relative locations of the major Project
components. The Phase 1 Open Pit outline is shown in the northeast area of the Project, along with
the ultimate (Phase 4) pit extents. Haul roads are shown connecting the Pit to the waste rock dumps-,
RSF-X located south centrally for Potentially Acid Generating (PAG)waste and WRD-A located in the
southwest for non-PAG (non-PAG) waste. The haul roads will also connect to the Non-Processing
Infrastructure (NPI) located in the northwest portion of the site and the ore sorting area and the ore
stockpiles, located on the east side of the project, just north of Interstate 85. A bridge over Interstate
85 will connect the ore stockpile area to the processing area, located immediately south of Interstate
85. South of the Processing Area, the Water Storage Basin 1 (WSB-1) will collect all contact water
produced within the Project area before being discharged from the site.
The main elements of the project 4eveloppment will be extending and deepening of the existing open
pit. WRD will take place in two locations around the site. The active life of mine is expected to be
11.5 years, including dewatering of the existing pit lake. Dewatering of the existing pit lake is planned
to last for approximately 24 months, assuming a discharge rate of 2,000 gallons per minute (gpm).
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Figure 1-3: Proposed Mine Plan
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Albemarle has provided yearly pit development plans, which indicate that the open pit extension will
primarily be oriented towards the south (1,300 ft extension), with minimal expansions planned in the
east and west directions relative to the current pit. The northern wall of the exiting open pit will not be
altered.The final pit bottom elevation is expected to reach 285 ft amsl by July 2035. The planned open
pit geometry is shown in Figure 1-4.
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SRK,2023 1_x-t 01z023 y FIGURE 1-4
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Figure 1-4: Planned Open Pit Development
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SRK Consulting(U.S.), Inc.
Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page 8
1.4 Objectives of Groundwater Study
The principal objective of the groundwater study for KMMP is to acquire sufficient hydrogeological and
hydrological data to develop predictive tools (numerical models) to support ongoing engineering PFS
work and permitting studies. The scope of work to achieve this includes the field characterization
programs carried out at site, as well as numerical modeling being described in the present report.
More specifically, the numerical modelling objectives related to the groundwater study are:
• Estimate groundwater inflows to the open pit (PFS).
• Propose a dewatering strategy for the open pit operation (PFS).
• Provide input to the site water balance (PFS, permitting).
• Evaluate post closure pit lake hydrogeology and provide input to geochemistry team for pit
lake water quality predictions (PFS, permitting).
• Evaluate estimated impacts on groundwater levels and stream flows (permitting).
• Estimate the impact of drawdown on adjacent groundwater users (permitting).
• Determine flow paths and capture zones during maximum mine development (permitting).
• Determine flow paths from WRDs to provide input to geochemical fate and transport
evaluations (permitting).
Surface water resource assessment, management, and groundwater chemistry analysis are handled
by separate teams of experts.Apart from the investigation of groundwater,the Surface Water modeling
report (SRK 2023a) contains comprehensive list of studies related to surface water characterization
and climate change. Furthermore, a thorough assessment of geochemical conditions is provided in a
separate report (SRK, 2023b).
1.5 Report Structure
The introductory section briefly describes the mine's location and provides a summary of the project
objectives and scope. Section 2 provides an in-depth description of project location and geographical
setting. Section 3 summarizes the field characterization program and its findings. Section 4
synthesizes the analyses to an updated conceptual hydrogeologic model (CHM) of the site, defining
the critical components that were incorporated into the NGWM. Section 5 outlines the NGWM
construction process, and demonstrates the NGWM calibration, i.e., comparing model outputs to
observed measurements. Sections 6 and 7 describe the model's long-term predictions for the mining
and post-mining phases respectively. Section 8 addresses the uncertainties related to these
predictions through the exploration of sensitivity analyses. Lastly, Section 9 summarizes the study's
conclusions.
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2 General Setting, Climate, and Geology
2.1 Topography and Geomorphology
The Kings Mountain area exhibits diverse topographic and geomorphological features reflecting the
long and dynamic history of geological and environmental processes. The landscape is primarily
composed of metamorphic rocks such as biotite gneiss, amphibolite, and schist, which have been
heavily weathered and eroded over time.
The terrain in the project area is characterized by undulating hills and valleys, with elevations ranging
from approximately 750 feet to over 1050 ft amsl regionally. The highest elevation within the project
area is approximately 1000 ft amsl, which corresponds to the catchment divide separating the north
and south watersheds of Kings Creek and Buffalo Creek. This divide is located to the west of the
existing Kings Mountain open pit.
Examination of pre-mining topographical maps has revealed that the long-term historic mining
operations have significantly altered the landforms of the project area. In addition to the two open pits
(Kings Mountain and Martin Marietta), two significant modifications to the natural topographical
landscape have been made: waste rock dumping to the north of the Kings Mountain Pit(Cardiac Hill)
and tailings deposition to the southwest of the open pit.
Figure 2-1 depicts a comparison between the pre-mining and current topographical maps of the project
area, emphasizing the noticeable extent of landscape changes that have occurred.
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Pre-Mining Topography(1906) Current Topography and Landform(2023)
o
v srk consulting Groundwater Modeling Study for Kings
Mountain Project
AA L B E M A R L E Project Area Topography Albemarle Corporation
ace.SRK,2023 —0412023 ,o.FIGURE 2.1
_• ==4 a.USPR000576
n+T hrT!:-=M1amamnr rnm=rnclW+I i9FPaPPcs .,lnrhl�' am ='0.5^b?ObyrKIP11%20Landsace IQ.PPM'Nreb-t
Source: USGS topographical Map
Note:Green line indicates boundary of the proposed open pit
Figure 2-1: Project Area Topography
2.2 Climate
The Project is situated within the Koppen-Geiger Cfa climate classification (Kottek, 2006), which
describes a continental type of climate without a dry season.Temperatures during the warmest months
are above 72 degrees Fahrenheit(°F), and temperatures in the coldest months are between 27°F and
65°F. Average monthly precipitation varies between 3 and 5 inches. Average annual precipitation is
42 inches, with an even distribution of rainfall throughout the year and an average annual snowfall of
4 inches. Southwestern North Carolina is prone to thunderstorms during the summer and ice storms
during the winter.
The climate of the Project vicinity is humid subtropical with hot summers and mild winters.The monthly
temperature ranges from a minimum of around YF in January to a maximum of around 104°F in
August, with an average temperature of around 60°F. Legacy data show that temperatures in the area
have been increasing, with an average rise of 0.3°F per decade since 1970, or roughly 1.7°F from
1895 to 2020. Climate change is expected to further contribute to this warming trend, potentially
impacting surface water conditions, such as increased evaporation rates and altered streamflow
patterns. Predictive climate models suggest further warming in the future, potentially resulting in more
frequent and severe heatwaves and droughts.
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Precipitation totals at the Project vary throughout the year. Based on the last 30 years, the area
typically receives between 41 to 55 inches of rainfall annually (Figure 2-2) with precipitation being
distributed relatively evenly throughout the year without a clear wet or dry season. The region is
susceptible to extreme precipitation events, such as tropical storms and hurricanes, which can bring
heavy rainfall and cause flooding.
Evaporation rates at the Project vary based on temperature, humidity levels, wind speed, and solar
radiation. Legacy data show that evaporation rates are highest in summer, averaging around 6 to
7 inches per month, and lowest in winter,with around 2 to 3 inches per month .Overall, average annual
evaporation ranges from 55 to 65 inches. Evaporation impacts surface water availability by contributing
to water loss from lakes, rivers, and streams. Factors such as vegetation cover, land use practices,
and soil moisture levels influence evaporation variability. Climate models predict that evaporation rates
will continue to increase in the future due to warming temperatures and changes in precipitation
patterns.
Distribution of Precipitation
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Annual Precipitation
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1925 1930 1935 1940 1945 1950 1955 19GO 19G5 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020
Figure 2-2: Annual Precipitation
2.3 Surface Water Resources and Pit Lake
The Kings Mountain Pit Lake, as well as the majority of the planned major mine units are situated
upstream of the Kings Creek Watershed, as shown in Figure 2-3. The planned WRD west of the pit
falls within the catchment boundary
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Figure 2-3: Surface Water Features Around the Mine Site
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Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page 13
In addition to the two open pit lakes, the significant hydrological units located within Kings Creek
watershed are:
• Kings Creek: originates from the northern part of the Martin Marietta open pit. Currently, it
flows into the pit, forming a storage pond for the Martin Marietta operation. After being utilized
for water supply to the operation, any excess water is discharged into the original creek
channel and flows southeastward.
• South Creek: a tributary to the southern part of Kings Creek. The proposed TSF is situated
along this creek channel. The discharge from the TSF will flow into South Creek Reservoir.
• South Creek Reservoir: a man-made reservoir that was constructed during the previous
mining operation. Its purpose was to store water for the previous mining activities.
• # 1 Pond: another man-made water storage facility. It was initially part of the previous mine
dewatering and water supply scheme.
• WSB-1: a pond that has formed on the previously developed Executive tailings dam. Outflow
from WSB-1 merges with Kings Creek.
Kings Mountain Pit Lake started to form after the previous mining operation ceased in late 1993/1994.
SRK generated a historical time series of pit lake elevations by compiling and analyzing publicly
available images from Landsat-5, Landsat-7, and Sentinel-2 satellites. SRK processed the compiled
satellite images with a suite of computer-aided design (CAD)/geographic information system (GIS)
software and Python scripts to estimate pit lake areas annually from January 1994 to January 2021.
The stage-storage-area relationship for the pit was then used to convert the annual pit lake area
estimates extracted from satellite imagery into pit lake elevations for use in the surface water and
groundwater models. A detailed hydrograph showing the pit lake recovery is provided in Section 3.4.3.
2.4 Geological Setting
2.4.1 Regional Geology
The Kings Mountain district is located in the central part of the Piedmont Plateau. The plateau ranges
in elevation from 750 to 1,050 ft amsl. The rocks of the Piedmont Plateau are both igneous and
sedimentary in origin, with various grades of metamorphism observed. The meta-sedimentary rocks
include assemblages of gneissic and schistose rocks.
At the regional scale, metamorphism has modified sandstones to quartzites, impure or shaly
sandstones to graywackes and gneisses, shales to schists, and limestones to marbles. Some of the
sediments were in part volcanic in origin, such as volcanic ash or tuff laid down in water with varying
amounts of detrital material derived from ordinary land waste. The metamorphism of these rocks has
produced varieties of crystalline rocks transitional between those of purely sedimentary origin and
those of purely igneous origin.
Some of the regional-scale igneous protoliths underwent high-grade metamorphism and transformed
to mica and garnet gneisses or schists. The metamorphism made some of the meta-igneous rocks
indistinguishable from similarly foliated rocks of sedimentary origin. Other less-metamorphosed
igneous rocks in the area are generally classified as granite, diorite, gabbro, pyroxenite, peridotite,
porphyry, and diabase.These igneous rocks represent intrusive and extrusive events, such as granitic
batholiths (and associated pegmatite stock intrusions)and surface lava flows.
Figure 2-4 shows a geological map of the site with an outline of the proposed open pit boundary.
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Note:Bedrock geology is shown with overburden removed.See Table 2-1 for description of acronyms and geological units. Dibs:Diabase Dikes.
Figure 2-4: Property Geology Map
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2.4.2 Kings Mountain Deposit
The Kings Mountain deposit lies within North Carolina's tin-spodumene belt and is located within a
larger-scale shear zone (the Kings Mountain Shear Zone [KMSZ]). The KMSZ is a northeast-striking,
steeply to moderately dipping zone of ductile and semi-brittle deformation and is at least 37 mi long
yet no more than a few hundred feet wide. The KMSZ is a boundary between two terrains within the
Piedmont Plateau, and it includes the Kings Mountain and Inner Piedmont Belts. The belts are
described as:
• Kings Mountain Belt: located east of the KMSZ and composed primarily of meta-sedimentary
rocks (quartzite, conglomerate, and marble) associated with mica schists (meta-sedimentary
and meta-volcanic in origin), as well as the High Shoals Granite.
• Inner Piedmont Belt: located west of the KMSZ and is primarily composed of mica gneiss and
mica schist(commonly with low undulatory dips).At a local scale,this includes the Cat Square
terrane, which is represented by muscovite schist and amphibolite, which have been intruded
by the (weakly-foliated) Cherryville Granite (and its associated pegmatite stocks, including
spodumene pegmatites).
Figure 2-5 shows a stratigraphic column of the local geology.
480
Sao Y i O
•i L
a) C upper mica schist N®
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720 m
Source: Dahrouge,2020,and Horton,2008
Figure 2-5: Stratigraphic Column
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Surface exposures on the Kings Mountain property are limited to areas of legacy mine workings. The
remainder of the property is either blanketed under a deeply weathered saprolite profile (rarely
preserving any remnants of the protolith) or overlain by historical spoils or stockpiles. Units of the Cat
Square terrane (Inner Piedmont) dominate the property and host the spodumene pegmatite deposits.
The eastern limit of the former open pit mine on the Kings Mountain property coincides with the KMSZ,
and as a result the units belonging to the Blacksburg Formation were largely observed from drill core.
Table 2-1 lists the represented lithologies at deposit/property scale (geological model units as
classified by Dahrouge Geological Consulting LTD (Dahrouge, 2020)).
Table 2-1: Geological Model Units
Lithology Model Unit Grouped Rock Units
Pegmatite Pegmatite
Intrusives Muscovite pegmatite Muscovite pegmatite
Spodumene pegmatite Spodumene pegmatite
Spodumene-muscovite pegmatite
Upper mica schist Upper mica schist
Shear schist 1
Shear schist Shear schist 2
Holmquistite schist
Hornblende (+/-biotite)gneiss
Horn blend e-epidote gneiss
Inner Amphibole gneiss-schist Horn blend e(+/-biotite)schist
Piedmont Hornblende gneiss-schist breccia
Terrane Biotite gneiss
Mica schist
Garnet-mica schist
Mica schist Pyrrhotite-mica schist
Quartzolite bands
Tourmalinite bands
Chlorite schist Chlorite schist
Silica mica schist Silica mica schist
MouKings Silica mica schist
Belt in -
marble Silica mica schist-marble transition zone
Belt transition zone
(Blacksburg Formation) Marble Marble
Phyllite Phyllite
Source: Dahrouge,2020
2.4.3 General Lithological Sequence
Considering the surficial deposits as well as the stratigraphic columns for the project area, a
generalized vertical geological sequence can be devised.Thus, geological units surrounding the Kings
Mountain deposit can be described as follows, with increasing depth:
• Overburden: Generally, residuum consisting of alluvial and regolith deposits. The residuum is
composed of clays from weathered bedrock, with some rock fragments as gravel and sand.
• Saprolite: Underlies the overburden, is soil that is derived from weathering of bedrock in-situ
where some of the original textures and structure of the bedrock are still identifiable; however,
the minerals have been altered by weathering to a consistency of soil.
• Weathered Bedrock (Transition Zone): A thin zone between the saprolite and the underlying
bedrock where there is less weathering, but the rock is still highly fractured, weathered, and
not competent.
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• Bedrock: KMMP below the transition zone is composed of metavolcanic amphibolite intruded
by pegmatites, mica schist, marble and phyllite. The Kings Mountain deposit is a Lithium-
bearing rare-metal pegmatite intrusion that has penetrated along the Kings Mountain shear
zone. The pegmatite field at KMMP is approximately 1,500 ft wide at its widest point in the
historic pit area, and narrows to approximately 400 to 500 ft in width at its narrowest point
south of the historic pit. Two contacts (upper Mica Shist/Amphibole Gneiss-Schist and Silica
Mica Schist/Schist Marble) play significant hydrogeologic roles as conduits and are shown in
cross-section in Figure 2-8.
2.5 Deposit Structural Geology
The rocks of the district have been extremely folded, metamorphosed, and faulted. The structural
features resulting from extreme compression generally run northeast-southwest, as is usual in the
Appalachian Mountains and Piedmont Plateau. Deformation on the Kings Mountain property mirrors
the regional events, with it being the dominant structural regime. Ductile shearing is evident in both
surface exposures and recovered drill core. Geometries for the units on either side of the KMSZ have
been most strongly influenced by the ductile deformation events and generally conform to the regional
strain, striking northeast to southwest, for this area.
Additional to the observed regional trends, a series of east-to-west trending, moderately- to steeply-
dipping, late brittle faults were observed in outcrop and in recovered drill core. These brittle faults
commonly have a normal sense of movement and negligible apparent displacements. Only one brittle
fault (EW-01) was interpreted to have a significant displacement on the property. EW-01 is a major
normal fault occurring at the northern end of the current pit; it has an east-west trend and a sub-vertical
dip. This fault has caused extensive damage and alteration in the surrounding rock. The location and
displacement cause by fault EW-01 is shown in Figure 2-6.
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I
7
r
Rl
i
+129C500 E +129G006E
1
+q.15 C
l
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0 500 1000 1
+1294MO E +1299000 E +1
Figure 2-6: Location of Fault EW-01 and Associated Lithological Displacement
2.6 Leapfrog Geological Model
Transposing the geological information to a numerical working space required two geological models
developed using the Leapfrog TM software. One model corresponds to the local deposit-scale model,
with greater lithological detail surrounding the Kings Mountain Deposit.The second model corresponds
to the regional scale leapfrog model, incorporating a larger domain, necessary for hydrogeological and
hydrologic considerations. Both models were used for the Project hydrogeological study.
2.6.1 Local Geological Model
A detailed deposit-scale geological model was developed by Albemarle and various consultants as
part of the exploration program, to provide information for mine planning purposes. A plan view and a
cross-sectional view of the geologic model provided by the client (Albemarle, 2023) are shown
in Figure 2-7 and Figure 2-8. This model was used in local hydrogeological analysis and provided
greater lithological detail for the NGWM.
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-ursaoo e
Legend
Proposed Pit Extents
f Existing Open Pit Extents
Upper Mica Schist
� Amphibole Gneiss-Schist
_ Spodumene Pegmatite
Shear Schist
Mica Schist
Po Mica Schist
J Chlorite Schist
�nnnnN Silica Mica Schist
Schist Marble
_ Marble
Phyllite
r
Srk consulting Groundwater Modeling Study for Kings
Mountain Project
`C L D E Ml R LE Geologic Model Plan View SSU=D-op Albemarle corporation
�EsRK.2023 1—041202a FIDURE No FIGURE 2.7
nie XXX -USPR000576
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Source:SRK 2023
Note:Overburden not shown for clarity.
Figure 2-7: Geologic Model Plan View
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Full_Rock_Name_ F:,
Merged_2016
■Amphibole Gneiss-Schist
■An ibolite
■Aplite
.Chlorite Schist
Diabase
0
Granite
Mafic
■Marble
Mica Schist
■Musc Peg
■NR
■Overburden
Peg
Epp phyllite
quartzolite
■Schist-Marble
Shear Schist
■silica Mica Schist
■SP.d Peg
Upper Mica Schist
■Water
300 +300
0 +0
Plunge 00
Azimuth 015
0 100 200 300
Source:SRK 2023
Figure 2-8: Geologic Model Cross-Sectional View
2.6.2 Regional Geological Model
As part of the hydrogeological study, a regional scale geological model with significant local
discretization in the mining area was developed by SRK. The model was used to support field data
analysis and the development of a conceptual hydrogeological and numerical groundwater model.
The regional scale geological model was generated from the following datasets:
• Overburden contacts
o Kings Mountain drillhole database from previous exploration programs:
• Faults and geologic contacts
o Geologic model utilized during the mineral resource estimate (2022 Prefeasibility)
• Surface geologic mapping and cross-sections from the United States Geological Survey
(USGS):
o Horton, 2008. And Goldsmith, et. al., 1988
• Regional water well data compiled by AECOM:
o GW-1 well construction forms submitted to the North Carolina Department of
Environmental Quality (NCDEQ) after well completion
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o Bedrock Wells, former Cinderella Knitting Mills (Superfund Site)
o Pasour Mountain Groundwater Monitoring and Research Station
o Department of Water Resources (DWR)wells
o USGS wells
Geologic units, including overburden, were modeled to a depth of -2,000 feet below mean sea level
within each domain. Geologic units were generalized based on descriptions and contacts that were
mapped or inferred by the USGS, except around the Kings Mountain resource, where geologic
contacts were used from drilling. Given that the regional geological model encompassed an area of
approximately 23 by 23 miles,thin or discontinuous geologic units (less than 1,000 feet wide)were not
modeled. For consistency, all geologic unit names and descriptions in the model were taken from
USGS mapping.
The extent of the overburden in the regional model was determined from two sources, namely,
overburden contacts observed in the SRK-led drilling at Kings Mountain, and water well data collected
by AECOM. The contact surface between the overburden and underlying bedrock was interpolated
between downhole data of overburden thickness, with zero tolerance (i.e., the surface was forced to
pass through all points). Due to the size of the dataset (36 wells and boreholes) and their localized
spatial distribution across the large model area, three domains did not present well data. For these, a
nominal depth of 50 feet was used. The average overburden depth of the 36 water wells used was
75 feet.
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3 Summary of Field Investigations
Extensive hydrogeological field investigations were performed at site in support of the groundwater
study for this project.This section provides a concise overview of these field characterization activities.
A detailed description of the field program is provided in SRK, 2023a.
The field investigations commenced in 2018 with the collection of hydrogeological data during an
exploration drilling campaign. Note that exploration drilling was not indented for collection of
hydrogeological data per-se. Therefore, hydrogeological insight was gained from the exploration
boreholes as a secondary and opportunistic benefit. Starting in the second half of 2022, drilling was
designed for hydrogeological data collection. The objectives of these field studies were as follows:
• Identify major hydrogeological units from hydraulic properties and behavior(further discussed
in the conceptual hydrogeologic model Section),
• Estimate hydraulic parameters (mainly transmissivity and hydraulic conductivity) of the units,
• Understand water levels within the groundwater system, including temporal trends,
groundwater flow direction, and variability of vertical hydraulic gradient versus depth,
• Establish a water level database, focusing on understanding pit lake hydrology during the
infilling process.
3.1 Drilling
Between 2018 and 2023, a total of 104 boreholes were used for hydrogeological data collection, with
combined total drilled length of 46,280 ft. Drilled borehole locations are shown in Figure 3-1.The drilling
campaigns for hydrogeologic characterization were overseen by SRK hydrogeologists.
Types of drilling included:
• 35 diamond coreholes
• 10 rotary boreholes
• 45 sonic boreholes
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Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page 23
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3.2 Hydraulic Tests
A total of 124 hydraulic tests were completed in various boreholes, including:
• Packer tests -26
• Slug tests - 51
• Short-term pumping tests - 15
• Long-term pumping tests - 7
• Spinner logging 0) in pumping wells—25
The locations of completed hydraulic tests are shown in Figure 3-2.
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3.3 Water Level Monitoring
A comprehensive groundwater monitoring system was installed at the site starting in 2018, to measure
water level elevations and water level changes in time. SRK collected water level data from a variety
of locations, including:
• 34 boreholes where water levels were collected during drilling and before grouting.
• 19 open diamond core holes equipped with surface casing and left open to the final depth
drilled.
• 15 stub wells installed in selected open holes for long-term water level monitoring (a stub well
is constructed by lowering well casing up to 2-inch diameter, equipped with a cement basket
attached at the bottom into competent bedrock ranging in depth from 30 to 100 ft below ground
surface [bgs]).
• 4 pumping wells, 2 deep monitoring wells (greater than 400 ft deep), 22 monitoring wells, and
1 temporary well.
• 5 grouted-in-place Vibrating Wire Piezometers (VWPs).
• 8 legacy wells found within the project boundaries (built circa 1974).
All accessible stub wells and 2 of the legacy wells were equipped with data-logging pressure
transducers. All downhole instrument data (apart from grouted-in VWPs) were verified with manual
measurements. Manual water level data were obtained using a water level measuring tape.
The locations of monitoring wells and points of measurement are shown in Figure 3-3.
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3.4 Surface Water Monitoring and Baseflow Analyses
This section provides a condensed summary of the surface water characterization activities, including
surface water monitoring locations and baseflow estimates for Kings Creek and South Creek. A
detailed description of the surface water monitoring program is provided in SRK, 2022 and SRK,
2023b.
3.4.1 Continuous Streamflow Monitoring
Streamflow at the project site is being monitored at two locations. The first, located at Monitoring Point
KMSW-3a, is a legacy concrete and steel plate weir designated as Weir#3, located on Kings Creek
below the confluence with South Creek and upstream of the culvert crossing under Highway 85. The
second is located at the outlet of South Creek Reservoir, just upstream of the confluence with Kings
Creek at Monitoring Point KMSW-8. The streamflow monitoring locations are shown on Figure 3-5.
Water level data from the two surface water monitoring stations are routinely downloaded, and stream
flows are calculated for reporting. In addition to continuous monitoring, Albemarle performs manual
streamflow measurements using a handheld acoustic instrument following the USGS discharge
measurement method (ISO 748:2021-Hydrometry). The first two sampling events were performed in
May of 2022 and October 2022.
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Figure 3-5: Locations for Surface Water Measurements
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3.4.2 Baseflow Estimates
Direct flow measurements on both Kings Creek and South Creek were used to estimate baseflows for
Albemarle's Kings Mountain project.A site visit was conducted on October 24 and 25th of 2022. Flows
were measured using a SonTek FlowTracker2 handheld Acoustic Doppler Velocimeter, which is a
portable and precise wading discharge measurement instrument. At the time of the measurements,
there had been no precipitation at site for 12 days. Table 3-1 shows a summary of the monitoring
locations,the corresponding tributary catchments,the measured flows and the baseflows per unit area
in both gpm/acre and cfs/acre.
Baseflows are presented as approximate values given that both catchments (South Creek and Kings
Creek) are affected by urban development in the upper parts, and by the presence of reservoirs.
Furthermore, Kings Creek is directly affected by flow discharges from Martin Marietta's reservoir and
South Creek upstream of Weir#3 is impacted by seepage from the legacy TSF.
Table 3-1: Baseflow Estimates for Kings Creek and South Creek
Tributary Measured Flow Baseflow Estimate Per Unit
Location Catchment Area
acres gpm cfs gpm/acre cfs/acre
Kings Creek downstream of Weir#3 1741 117 0.26 0.067 0.00015
South Creek upstream end 221 70 0.16 0.320 0.00072
South Creek northern end of TSF 324 125-148 0.28-0.33 0.390-0.406 0.00090-0.00100
Kings Creek upstream of Weir#3 552 178 0.40 0.320 0.00072
3.4.3 Pit Lake Water Level Monitoring
Several pressure transducers were installed to monitor pit lake elevations and barometric pressure at
the pit lake. However, access to these transducers has been limited due to rising water levels and pit
slope stability hazards. These restrictions have impacted data continuity since installation, resulting in
sporadic measurements when a surveyor would measure the surface of the pit lake. Figure 3-6 depicts
the generated hydrograph of the pit lake elevation based on satellite images and methodology reported
in Section 2.3. The purpose of barometric pressure monitoring is to enable the removal of barometric
pressure effects from measured transducer data. It is most useful when barometric pressure is
monitored at a location near to the water level transducers requiring barometric correction. Therefore,
a barometric pressure transducer was installed on the edge of the pit lake. Figure 3-7 shows the
locations of the transducers in the pit lake.
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Figure 3-6: Pit Lake Recovery Hydrograph
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Figure 3-7: Pit Lake Elevation and Barometric Pressure Monitoring Locations
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3.5 Seep and Spring Survey
SWCA conducted seasonal hydrocensus studies to characterize seeps and spring in the project area
(SWCA 2022a). During surveys conducted in February and March 2022, a total of 16 seeps and
23 springs were identified as shown in Figure 3-8. The surveys took place under average rainfall
conditions, providing a representation of typical conditions in the Project area. Flow saturation of seeps
and spring appear to remain persistent throughout the year,with certain flow reductions during periods
of low rainfall (confirmed through site visits in September and October 2022).
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3.6 Groundwater Well Inventory Survey
A groundwater well survey was performed by AECOM (AECOM,2022a) within the vicinity of the
project, consistent with the extents of the numerical groundwater model presented in this report. The
scope of the survey consisted of the following:
• Determine the source(s) of municipal water supply near the site. Municipalities consist of the
city of Kings Mountain, Cleveland County, and Gaston County.
• Review publicly available information on public and private water supply wells within 4 mi of
the site, including online databases and historic reports that included receptor surveys.
• Conduct a drive-by inspection of properties within 2 miles of the site using Google Streetview
(GSV).
• Gather as much information as possible on pre-existing groundwater quality of naturally
occurring elements.
AECOM reviewed publicly available databases (including the Source Water Assessment Program
(SWAP) database, Cleveland County well construction and water sampling records, historic
environmental sampling reports, and visual confirmation using GSV) within the NGWM boundary.
AECOM classified wells as "confirmed present' or"suspected as present".
AECOM found that approximately 260 confirmed or suspected wells have been identified to date.
Though most are suspected, at least 56 wells have been positively identified based on previous
environmental investigations (reports as old as the early 1990s), well construction, and/or laboratory
data since 2010. Locations are based on parcels and do not reflect exact coordinates. Many are within
the two-mile radius, particularly those suspected through google street view observations.
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4 Conceptual Hydrogeological Model
A conceptual hydrogeological model (CHM)corresponds to a simplified,schematic model which allows
for a clearer understanding of the hydrogeological system at a particular site. The main components
of the CHM that affect flow and water levels are grouped and synthesized to represent all elements of
the hydrogeological regime. The CHM forms the basis for numerical models, as the latter are
mathematical representations of the former.A schematic representation of CHM components at Kings
Mountain are represented in Figure 4-1.
In general terms, the conceptual hydrogeological model subdivides the groundwater system into two
main components, namely, surficial regolith and deeper bedrock. The upper regolith, composed of
overburden, saprolite and weathered bedrock, is considered the high hydraulic conductivity
component in the groundwater system (0.1 to 0.5 ft/day). Most of the drawdown from mining is
understood to occur in the surficial regolith, both historically and during future mining. The historical
recovery of the pit lake is believed to be mainly through recharge and flow in the surficial regolith.
In contrast, hydraulic testing in the bedrock suggests low to medium hydraulic conductivity(1x10-4-0.3
ft/day),with hydraulic conductivity decreasing with depth. Flow in the bedrock is expected to be mostly
controlled by fractures, which are mostly present at shallower depths close to the weathered zone.
Therefore, mining operations are likely to affect water levels in the deep bedrock component to a lesser
extent than in the overlying regolith.
In addition to these components, hydraulic testing identified two major water-bearing lineaments in the
bedrock, at geological contacts east and west of the Kings Mountain pit. These lineaments have been
labeled the Southeast and Northwest Shear Contact Zones, respectively, and have shown hydraulic
conductivities similar to, or higher than,those observed in the regolith. The following sections describe
the various CHM components in greater detail, focusing on interactions between the components and
their effect on the groundwater system.
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C1 I
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t11 Kings Mountain Open Pit:Lake formed after the end of the historic mining Baseflow analyses suggested that 12-20%ofthis amount enters the I "sue
period(1994}-It recovered to 820 ft asl approximately in 20 years-The bottom groundwater system as recharge,and dtscharges to surface water and lakes- r-"-"-•-�`-. _ `. x2..
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of the existing take is 560 ft asl.Inflow to the previous operation was
"Im fated at around 100-260 gp m. low permeable bedrock.
(21 Martin Marietta quarry:Lac ated in low perm eability+Marble Unit.The water 6) Regolith:Consists of soil,low permeable saprolite,and relatively permeable I 1
level in the quarry is being regulated by the current operation at around 620 ft weathered zone.The test suggests weathered zone K as:0.1-0.5 ft/day. I �mocx`nI
asl-No seepage was observed at the pit walls,suggesting a low-permeability Spinner logging was conducted to explore the presence of a transition zone I —
setting with limited interaction with the KM pit lake- between the bedrock and the weathered zone.Thesetests reveal that the 1 .wc,urro murex
(3) Water table(2023}:The existing pit lake governs the shape of the current transition zone has a limited extern,is sparse,and is not connected-
water table.The pitllake has lowered the pre-ruining water'evel in nearby 7) Bedrock hydraulic conductivity:(K1 Is determined via comprehensive aquifer
overburden and upper fractured zone. tests-Tests suggest mostly low to medium range(IE-4ft/d to 0.3 ft/day). I 1
Packer test profiling indicated that K decreases with depth due to the absenre
{4� Water Table{2035�;Proposed open pit will dower the water table to 286 fit asl I
f foractu m-
at the center of the pit.This will create additional but limited drawdown to I Hamel arid
8} Shear Contact 2.ones ISoutheast and Northwest}:A slightly increased ❑aniel,lid9Y
n ea cloy weathered and upper fracture units as these zones am readily I—— I
impacted bythe currentlake level. lineament was determined during field characterization.5hear�Cantact zone K ———— ——————————
is determ ined in the ra nge of 0-2-1-8 ft/day
Figure 4-1: Conceptual Hydrogeological Model of Kings Mountain Pit Area
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4.1 Hydrogeological Units
A hydrogeological unit (HGU) is a subsurface rock or soil layer that is characterized by a relatively
uniform set of hydraulic properties that control the movement and storage of groundwater within it. The
hydrogeological system is simplified into a finite number of volumes with average hydraulic
parameters, which can represent the complex groundwater system. This simplification, however,
cannot account for local heterogeneities that may affect the flow regime at a smaller scale.
At Kings Mountain,a total of 12 distinct HGUs were defined based on lithology,alteration and hydraulic
testing. The regolith was divided into three different HGUs,while the bedrock was represented by nine
distinct units. All of these HGUs were later incorporated into the numerical modelling.
4.1.1 Regolith
Most bedrock geologic units are overlain by regolith,which is a mixture of soil, alluvium,and weathered
rock material. Some areas of the regolith have been transported and deposited as glacial drift,
colluvium,or alluvium,while other areas consist of residuum or saprolite,which has weathered in place
and remains on top of the parent rock. The thickness of the regolith varies throughout the study area,
from absent in some areas to over 150 ft in others. The regolith was subdivided into three HGUs:
• Overburden: a mixture of soil, glacial drift, colluvium, or alluvium. These sediments are
relatively permeable and partially saturated. The water table is located mainly within the
overburden, except in areas where it was drained as a result of historical mining.
• Saprolite: a type of clay-rich, residual material that is formed predominantly through
predominantly in-situ chemical weathering of bedrock. in place. Typically, this the saprolite
consists of of a relatively low-permeability clay layer. It varies in thickness from approximately
30 to 400 ft and is found overlying a large part of the study area, except where it is cut by
drainages.
• Weathered Bedrock (or Transition Zone): a zone characterized by a gradual shift from
unconsolidated material to bedrock. This zone has enhanced hydraulic conductivity from local
fractures, as identified by spinner logging data.
4.1.2 Bedrock
The bedrock below the Transition Zone is composed of metavolcanic amphibolite intruded by
pegmatites, mica schist, marble,and phyllite silica mica schist.The Kings Mountain deposit is a lithium-
bearing rare-metal pegmatite intrusion that has penetrated along the KMSZ.The pegmatite field at the
project area is approximately 1,500 ft wide at its widest point, in the legacy pit area, and narrows to
approximately 400 to 500 ft in width at its narrowest point south of the legacy pit.
The bedrock HGUs were developed by grouping lithologies exhibiting similar hydraulic properties using
the regional and local Leapfrog geological models. For example, the amphibolic gneiss, schists, and
pegmatites hosting the deposit were grouped in a "Shear Zone" HGU. Similarly, all undifferentiated
bedrock outside of the mining area were grouped into a single HGU.
The marble unit found to the east of the pit, outcropping in the Martin Marietta quarry, had a distinct
low hydraulic conductivity that differentiated it from the surrounding rock. This unit was then therefore
considered a standalone HGU and distinguished from adjacent geological units. Additionally, the
western and eastern shear contacts were defined as unique HGUs. As a result, the Iithologies directly
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adjacent to these contacts (muscovite schist to the west, silica schist and schist marble on the east)
were considered as unique HGUs as well.
In summary, the identified bedrock HGUs include:
• Shear Zone (combination of Amphibolic Gneiss Schist, Spod Pegmatite, Shear Schist, and
Mica Schist)
• Shear Contact (Northwestern)
• Shear Contact (Southeastern)
• Muscovite Schist
• Silica Mica Schist
• Schist Marble
• Marble
• Philitic Metastone
• External bedrock (represent area undifferentiated bedrock outside of the mining are)
Additionally, it was found that bedrock hydraulic conductivity generally decreases with depth for most
units.
4.2 Hydrogeological Significance of Major Faults
Two Shear Zone contacts, described above in Section 4.1, were incorporated into the model. The first
contact is located between Muscovite Schist and Shear Zone units, while the second is located
between Silica Mica Shist and Schist Marble (both contacts are shown in Figure 4-1). These contacts
are interpreted as transmissive features based on pumping tests conducted in wells penetrating these
features.
The east-west trending structure identified as EW-01 (shown in Figure 2-6:)was investigated through
packer testing. The results indicated that there were no significant variations in hydraulic parameters
This structure is located along the northern pit boundary, where the EW-01 fault zone is related to a
lithological offset north of the Kings Mountain open pit and south of the Martin Marietta quarry. Since
its hydraulic effects were found to be minimal, the fault zone was not considered in this study as a
separate HGU.
4.3 Hydraulic Conductivity and Transmissivity Values
One of the key objectives of the field investigations was to determine hydraulic parameters of different
hydrogeological units at different depth intervals. Results of the field investigations are shown as
follows:
• Summary of hydraulic conductivity values per hydrogeological units is shown in Table 4-1.
• Transmissivity values estimated from pumping tests are shown in Figure 4-2.
• Profile of estimated hydraulic conductivity values versus depth is shown in Figure 4-3.
• Hydraulic conductivity values of regolith units, estimated from spinner logging data collected
in pumping wells, are shown in Figure 4-4.
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SRK Consulting(U.S.), Inc.
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US PR000576
Figure 4-2: Map of Transmissivity Estimated by Pumping Tests
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Table 4-1: Summary of Hydraulic Testing of Hydrogeological Units
Modeled Hydraulic
Geologic Unit from No.of Transmissivity(ft2/day) Hydraulic Conductivity(ft/day) Conductivity(ft/day)per
Numerical Groundwater Tests De th ft
Model Minimum Maximum Average Geomean Minimum Maximum Average Geomean :200 200-600 >600
Regolith 1) 13 0.38 466.81 70.40 22.05 4E-03 2E+01 3E+00 3E-01 N/A N/A N/A
Overburden 4 N/A
Saprolite Differentiated Using Spinner Log Evaluation 0.09 N/A
Weathered Bedrock 0.4 N/A
Muscovite Schist(West) 1 3.88 3.88 3.88 3.88 2E-02 2E-02 2E-02 2E-02 5E-03 0.001 1 0.001
Marble 5 0.03 1.03 0.38 0.21 7E-05 2E-02 3E-03 8E-04 0.001
Schist-Marble 3 0.03 0.90 0.38 0.18 2E-04 6E-03 2E-03 9E-04 1.0E-02 0.0075 0.001
Shear Contact(North) 2 11.42 657.8 334.6 86.7 1 E-01 3E+00 1 E+00 6E-01 2.0E-01 0.2 0.001
Shear Contact(South) 3 24.34 111.50 60.36 49.71 7E-02 5E-01 3E-01 2E-01 2.0E-01 0.2 0.001
Shear Zone Units 32 0.01 231.50 44.96 4.322 4E-05 5E+00 4E-01 2E-02 5.0E-02 0.01 0.001
Silica Mica Schist 3 0.02 26.62 9.49 1.97 1 E-04 5E-01 1 E-01 1 E-02 1.0E-02 0.0075 0.001
Note: 1)Regolith was divided in the NGWM to Overburden,Saprolite,and Weathered Bedrock hydrogeological units.
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Profile of Hydraulic Conductivity Versus Depth
0
1
sao T
41�
1000tio
y 1 1
Q
0 1500 ❑Regolith
■Marble
■Muscovite Schist(West)
■Shear Zone Units
2000 ■Schist-Marble
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■Shear Contact(South)
■Silica Mica Schist
2500 0
O o 4 C O o 4 G
w Lq LU u.i + + +
w w w
Hydraulic Conductivity(ft/day)
Note:Error bars represents tested interval.
Figure 4-3: Distribution of Measured Hydraulic Conductivity Values per Depth for Individual
Units
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Profile of Hydraulic Conductivity Versus Depth
n
1
1
50 I*
1
100
t
n
0
1
200 O Overburden
B Saprolite
■Weathered Bedrock
250
1.E-03 1 1.E-01 1.E+00 1.E+01
Hydraulic Conductivity(ft/day)
Note:Error bars represents tested interval.
Figure 4-4: Distribution of Hydraulic Conductivity Using Spinner Log Evaluation
Results of hydraulic field testing are summarized as follows:
1. The total transmissivity of the tested groundwater system ranges from 0.013 to 658 ft2/day,
with geometric and arithmetic means of 4.8 ftz/day and 52 ftz/day, respectively (as shown in
Figure 4-2).
2. Pumping tests were conducted at 13 wells screened within the regolith. The pumping test
results show hydraulic conductivity values ranging from 0.004 to 21.9 ft/day with a geometric
mean of 0.33 ft/day. Note that these values include upper bedrock units below the weathered
zone in some of the tests.
3. Spinner logging allowed for differentiation of hydraulic conductivity values of sub-layers within
the regolith unit. Different depth intervals within the 13 wells screened within the regolith were
analyzed, yielding the following results:
a. Overburden hydraulic conductivity was estimated from 8 intervals, ranging from 0.03 to
0.5 ft/day, and a geometric mean of 0.14 ft/day.
b. Saprolite hydraulic conductivity was estimated from 6 intervals, ranging from 0.005 to 2.0
ft/day, and a geometric mean of 0.1 ft/day.
c. Weathered Bedrock hydraulic conductivity was estimated from 12 intervals, ranging from
0.002 to 3 ft/day, and a geometric mean of 0.22 ft/day.
4. Packer test profiling conducted in the bedrock units indicated significant decrease in hydraulic
conductivity with increasing depth (shown in Figure 4-4. This decrease in hydraulic
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conductivity was found to be correlated with a reduction in both fracture frequency and fracture
aperture size, both found through geotechnical of the coreholes.
5. Hydraulic tests conducted to the south of the KMSZ revealed that the marble unit in that area
exhibits low hydraulic conductivity. The geometric mean of the hydraulic conductivity
measured in the marble unit, considering the five tests performed in the unit,was 8x10-4 ft/day.
This low hydraulic conductivity value suggests that the marble unit may act as a barrier to
groundwater flow and restrict the movement of water through the subsurface.
6. The pumping tests conducted in the shear contact zones (located at the northwestern and
southeastern boundary of the KMSZ)yielded the highest hydraulic conductivity values among
all tested bedrock units. The hydraulic conductivity values of the shear contact zones ranged
from 0.007 to 4.5 ft/day, indicating that these zones have a relatively high capacity to transmit
groundwater. Estimated geometric mean values of hydraulic conductivity within the
northwestern and southeastern Shear Contact Zones are 0.7 ft/day and 0.2 ft/day,
respectively.
7. The packer test conducted in the EW-01 fault zone (offsetting fault located north of the Kings
Mountain open pit and south of the Martin Marietta quarry) revealed that there was no
significant enhancement or reduction in hydraulic conductivity in this zone, as compared to
surrounding HGUs. This suggests that the fault zone does not act as a barrier to groundwater
flow, nor does it serve as a distinct conduit to groundwater flow.
4.4 Groundwater Storage
Groundwater storage parameters were not reliably determined from the pumping test due to limitations
of the monitoring well network and duration of the tests. Initial storativity values (both specific yield and
specific storage)were assigned in the NGWM based on literature data and SRK experience in similar
conditions. These values were then adjusted during the NGWM calibration process, to match
groundwater level trends and pit lake recovery. Calibration results are discussed in Section 5 below.
4.5 Heterogeneity and Anisotropy
During the field hydrogeologic characterization, heterogeneity and anisotropy were observed in some
tests at the local scale. At the regional scale, all HGUs were assumed isotropic and homogeneous in
the NGWM, with two exceptions:
• The overburden unit was assigned hydraulic conductivity anisotropy of Kh:Kv=10:1, and the
overburden unit was assigned hydraulic conductivity anisotropy of horizontal hydraulic
conductivity (Kh)to vertical hydraulic conductivity (Kv)of 10:1.
• Hydraulic conductivity values of bedrock units were decreased with depth, following a step
function with depth intervals of 0-200 ft, 200-600 ft, and greater than 600 ft bgs (described in
Section 5 below).
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4.6 Recharge - Discharge
Water inputs to the groundwater system occur mainly through recharge from precipitation. A fraction
of precipitation percolates through the different regolith units and recharges the groundwater system.
In the bedrock system, recharge occurs mainly through fractures and the weathered zones of the intact
rock. A limited portion of the recharge is assumed to follow a deeper flow path in low- permeability
bedrock. Groundwater recharge in the vicinity of the Kings Mountain pit area is between 12% and 20%
of mean annual precipitation (MAP),which averages at 46 in/yr based on last 30-year record (PRISM).
Recharge varies spatially based on local soil conditions and level of urbanization.
Outflow from the groundwater system follows a regional path or a local discharge path to the creeks
and streams from shallow groundwater. In the area of the pit lake, groundwater generally flows from
the northwest to the southeast. Around the Kings Mountain and Martin Marietta pits, the water table
has been affected by legacy mining, exhibiting concentric flow towards the excavations. The Kings
Mountain pit lake levels have been historically lower than surrounding groundwater levels, indicating
discharge from the groundwater system to the lake.
4.7 Groundwater Flow and Water Levels
Groundwater flows from topographic high points toward creeks at topographical lows. The outflow
occurs through these creeks, or as groundwater flow at the boundaries of the study area.
The current groundwater contours around the Kings Mountain pit and direction of groundwater flow
are shown in Figure 4-5.The figure also shows latest water level elevations measured at various wells,
from July 2022 onwards. At the local scale, groundwater contours follow the hilly topography around
the pit area, while the Kings Mountain and Martin Marietta pits have formed cones of depression,
directing groundwater flow towards them.
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Figure 4-5: Map Showing Water Levels and Distribution of Groundwater Flow
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SRK Consulting(U.S.), Inc.
Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page 49
Water table gradients around the Kings Mountain pit are not uniform, as shown by the density
distribution of contour lines. The western and southern pit walls show the steepest gradients, meaning
that water levels are higher along these pit walls. In contrast, the northern and eastern walls of the pit
appear to be more drained, meaning a flatter water table around these areas, likely affected by
dewatering at the Martin Marietta pit.
Overall, the Kings Mountain pit appears to be a gaining hydrological system, meaning that the pit lake
is still filling up from the groundwater flow towards it. A hydrograph of water levels of the Kings
Mountain pit lake is shown in Figure 3-6. The water level trend indicates fast recovery during the initial
phase of infilling, when gradients between the lake elevation and surrounding groundwater were
greatest. The fast recovery is followed by a slower recovery rate (years 1999 to 2012) due to water
management activities that included pumping water from the lake. The final phase of the recovery of
the pit lake was at a lower rate than in the initial recovery phase. The current pit lake elevation is
817.8 ft amsl (measured on 04/17/2023).
Hydrographs from all groundwater monitoring points were analyzed,water level trends were identified,
and possible connections to the pit lake were assessed. An attempt was made to group the
groundwater level trends at the various monitoring points. However, interference between pit inflow,
precipitation and non-mining related activities did not allow for clear groups to be devised.
Groundwater flow in proximity to the pit slopes is expected to have a vertical component. Downward
vertical gradients are expected near the topmost saturated part of the slope, forcing flow towards the
toe of the pit slope. Flow directions gradually change approaching the pit bottom, where upwards flow
gradients are expected. This behavior is currently observed near the pit and is expected to be more
pronounced once the pit lake is fully dewatered and further excavation takes place. Measured vertical
hydraulic gradients in the pit area are shown in Figure 4-6. Available data from four strings of grouted-
in transducers (represented by red spheres in Figure 4-6) indicate presence of both upward (expected
during pit lake recovery)and downward (typical for natural conditions) hydraulic gradients.
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950
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Figure 4-6: Vertical Hydraulic Gradient Measured in Proximity of Pit Lake
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4.8 Conceptual Mine Development and Post-Mining Conditions
A conceptual model of future mining and post-mining conditions was developed, building upon the
hydraulic testing, analyses, and results presented in previous sections. Figure 4-7 depicts a schematic
conceptual interpretation of the groundwater system during mine development and post mining. During
the mining phase, future dewatering of the existing pit lake, excavation of the proposed pit, and in-pit
dewatering will cause the water table to lower, and drawdown to propagate laterally away from the pit.
The shallower regolith units are expected to be the most impacted by the dewatering and drawdown
propagation, while changes in the underlying low-permeability bedrock are expected to be limited in
comparison to the regolith. Estimated groundwater inflow to the proposed pit should be larger than
observed for historical pit but should not exceed historical rates by factors of 1.5 to 2.
Following the mining phase,the pit will be backfilled,and a new pit lake is expected to form. The lowest
elevation of the pit rim is expected to be 850 ft amsl. Therefore, the future pit lake formed after infilling
could spill over at this elevation into the surface water system, given that precipitation and surface
runoff exceed lake evaporation rates at the site. Some pit lake outflow into groundwater system is also
expected since the future pit lake elevation will exceed water level in current pit lake by about 30 ft.
This reversal in gradients from the pit to the groundwater system is expected to occur near the spillover
point.
A NGWM was constructed to assess the validity of this conceptual model. The following section details
the NGWM construction, calibration, and results of predictive simulations. Assumptions and
simplifications that guided model development are discussed as well.
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SRnConuvmng(U.S.), Inc.
Hydrogeological Study Groundwater
Mining Condition
Post-Miring Condition
1:Pre-mining condition
2 End oiHistoritai Miring
�Cu—nit Pit take
4:Proposed Pit Extent
6i Post-mining Pit Lake
Grotind-iter Moelieling Study for Kings
Conceptual Mine Development
and Post MininU Condition
Figumy4'7: Conceptual Model of Groundwater Conditions during Mine Development and Post-
Mining

SRK Consulting(U.S.), Inc.
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5 Numerical Groundwater-Flow Modeling
The numerical model was designed to estimate groundwater inflow to the proposed open pit, pit lake
recovery following mining operation, and water level changes and impact to groundwater system
during proposed mining and post-mining conditions. SRK developed the NGWM for the Kings
Mountain project using MODFLOW-USG, which is a control-volume finite-difference (CVFD)
groundwater flow simulator (Panday et al., 2013). The Groundwater Vistas graphical user interface
(version 8)was used for pre-and post-processing (ESI, 2020).
MODFLOW-USG is a version of the groundwater flow code MODFLOW that utilizes Un-Structured
Grids. An unstructured grid formulation provides flexibility to a MODFLOW simulation by enabling
localized refinement or coarsening of the model domain grid. Flexibility in grid design enables
adjustment of grid cells to conform to small-scale features such as creeks and faults, and more
flexibility compared to traditional finite difference models that can only accommodate orthogonal grid
cells. The Kings Mountain NGWM used an unstructured grid comprised of Voronoi polygons.
MODFLOW-USG also provides mass-conserved, robust, and efficient numerical solutions without the
computationally intensive numerical integration, elemental assembly schemes, and expanded matrix
connectivity associated with finite element methods.
Predictive models need to demonstrate the ability to reasonably reproduce past observations, in order
to reduce predictive uncertainty.To simulate future mining and post-mining conditions, SRK developed
five sets of models, each simulating a separate set of conditions:
• Historical mining (with a pre-mining steady state stress period for initial conditions)
• Historical post-mining (historical pit lake recovery)
• Future mining (predictive)
• Future post-mining (predictive), which was simulated using two separate models:
o Increase in groundwater level leading to backfill saturation
o Development of future pit lake above backfill
The structure of groundwater modeling conducted for the Kings Mountain project by SRK is
summarized in Figure 5-1.
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Models: Calibration to: Predictive parameters:
Historic Mining Water levels P
-Steady State Groundwater it lake surface elevation
and Transient inflow to pit Groundwater inflow to pit
Water level lake
(Model 1) Baseflows changes Pit lake spillover to
Model setup Reduction in surface water
Historic Post- baseflow Pit lake outflow to
Historic pit lake groundwater
�. Mining- recovery and
Transient Maximum drawdown
groundwater extent
(Model2) inflows
• Reduction in baseflow
Historic pit Long-term water table
plans and pit
lake design Pumping tests
Future Mining and Future mining Future post-mining
Post-Mining �E
—
Transient(Models
3,4 and 5 Mine plans gackfilllPit Lake design and
and facilities facilities at closure
Figure 5-1: Structure of Groundwater Modeling for the Kings Mountain Project
The historical mining model was developed with a steady-state stress period as the first stress period,
to simulate the initial hydraulic head distribution for the subsequent transient model runs. After the
steady-state stress period, a transient model simulated legacy mining under assumed conditions. The
historical post-mining model was a transient model that was calibrated to field data and set the present-
day groundwater conditions as basis for the predictive models. The predictive models were used for
assessment of future mining and post-mining conditions. Figure 5-1 shows interactions between the
models, calibration targets and predictive parameters.
5.1 Grid Discretization and Physical Model Boundaries
The NGWM had 304,860 grid cells across 20 vertical layers and covered an area of about 200 mil.
The grid cells varied in width from 1 to 3,700 ft and thickness from 5 to 515 ft. The uppermost grid cell
elevations were assigned based on available topographic maps. The total thickness of the model was
2,020 to 2,482 ft.A plan view of the model extent and model grid cells is shown in Figure 5-2. Figure 5-3
shows a 3-dimensional view of the grid cells of the groundwater model. Figure 5-4 shows the simulated
boundary conditions for the model.
The grid was designed to:
• Refine areas around pit, surrounding monitoring wells, and creeks.
• Incorporate boundaries between hydrogeological units and geological contacts.
• Maintain appropriate refinement around the pit and monitoring wells to provide accurate
results where sharp gradients were expected,while allowing reasonably-fast model run times.
The lateral and vertical extents of the model were defined to simulate water level changes resulting
from the future open pit excavation. The bottom of the model was assumed to be a no-flow boundary,
set to 1,420 feet below sea level in the area of the planned pit..The lateral boundaries were designated
as no-flow boundaries, with the exception of four groundwater outflow areas beneath the following
creeks:
• Kings Creek (at the southwestern model boundary)
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Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page 55
• Clark Fork (at the southern model boundary)
• Crowders Creek (at the southeastern model boundary)
• Long Creek (at the northeastern model boundary)
To approximate groundwater outflow in these four areas,constant head (CHEAD) boundary conditions
were assigned with elevations set 5 ft below creek elevations. The four areas allowing groundwater
outflow are shown on Figure 5-4. While this is a simplified approach to simulate groundwater outflow
through the model boundaries, the main purpose of these boundary conditions was to allow
groundwater outflow at reasonable locations and avoid mounding of the simulated water table above
the ground surface. The use of this simplified approach did not affect any mining predictions due to
the significant distances of these boundaries from the mine.
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SRK Consulting(U.S.), Inc.
Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page 56
T
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•w•- -- wUSPROW576
Figure 5-2: Plan View of Model Domain and Location of Simulated Surface Water Bodies
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Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page 57
.seo0w'
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AA L B E A R L E ° -- -- 3a View of Model Grid i®u®ra Albemarle Corporation
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Figure 5-3: 3D View of Model Grid
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SRK Consulting(U.S.), Inc.
Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page 58
l
jt /•
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Figure 5-4: Simulated Boundary Conditions
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Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page 59
5.2 Simulation of Hydrogeological Features
5.2.1 Simulation of Hydrogeological Units
In the finite-difference method, hydraulic properties are assigned to a grid cell, hydraulic heads are
associated with their centers,and fluxes are assigned by computing Darcy's Law across the cell edges.
Therefore, every cell in the model was assigned a model "zone", as depicted in plan-view on Figure
5-5, and cross-section on Figure 5-6 and Figure 5-7. Each model zone was assigned values for
horizontal (Kh) and vertical (Kv) hydraulic conductivity, specific storage (Ss), and specific yield (Sy)
based on historical aquifer testing data. Specific yield of a given grid cell is considered in the numerical
solution only when the simulated water table occurs within that grid cell. Distributions of simulated
HGUs (zones)for all model layers are shown in Appendix A.
Thirteen HGUs were incorporated into the groundwater model based on the Leapfrog geological
model. These include:
• Overburden
• Saprolite
• Weathered bedrock
• Shear Zone
• Shear Contact (Southeast)
• Shear Contact (Northwest)
• Muscovite Schist (West)
• Mica Schist
• Silica Mica Schist
• Schist Marble
• Marble
• Phyllitic Metasiltstone
• External Bedrock
Hydraulic conductivity values of the last nine units (Shear Zone through External Bedrock) were
assumed to decrease with depth using a step function approximation:
• Depth from 100 to 200 ft
• Depth from 200 to 600 ft
• Depth more than 600 ft
Table 5-1 shows the hydraulic properties used in the model for these hydrogeological units. A
comparison of the modeled and measured values of hydraulic conductivity for ten major HGUs is
shown in Table 5-2. All units were assumed to be isotropic with the exception of overburden where
vertical anisotropy Kh:Kv=10:1 was applied. A cross-section comparison of the simulated
hydrogeological units versus the Leapfrog geologic block model is shown on Figure 5-8.
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Hydrogeological Study and Groundwater Modeling-Kings Mountain Mining Project Page 60
Table 5-1: Hydraulic Properties Used in Numerical Groundwater Model
Hydraulic Conductivity K Specific
Hydrogeological Unit Sub (ft/day) Specific Storage
Units/Depth Kx Ky Kz Yield (Sy) Ss(1/ft)
Surficial Overburden 4 4 0.4 0.15 2.00E-05
Deposits Saprolite 0.09 0.09 0.09 0.05 2.00E-05
Weathered Bedrock 0.4 0.4 0.4 0.1 2.00E-05
<200ft 0.2 0.2 0.2 0.01 1.00E-06
Shear Contact 200 ft to 600 ft 0.2 0.2 0.2 0.01 1.00E-06
(Southeast)
>600 ft 0.001 0.001 0.001 0.01 1.00E-06
<200ft 0.2 0.2 0.2 0.01 1.00E-06
Shear Contact 200 ft to 600 ft 0.2 0.2 0.2 0.01 1.00E-06
(Northwest)
>600 ft 0.001 0.001 0.001 0.01 1.00E-06
Mica Schist <200 0.1 0.1 0.1 0.03 2.00E-06
<200ft 0.05 0.05 0.05 0.03 2.00E-06
Shear Zone <200 under pit 0.2 0.2 0.2 0.03 2.00E-06
Units 200 ft to 600 ft 0.01 0.01 0.01 0.01 1.00E-06
>600 ft 0.001 0.001 0.001 0.005 1.00E-06
<200ft 0.005 0.005 0.005 0.01 1.00E-06
Muscovite 200 ft to 600 ft 0.001 0.001 0.001 0.005 1.00E-06
Schist(West)
Bedrock >600 ft 0.001 0.001 0.001 0.005 1.00E-06
Units <200ft 0.01 0.01 0.01 0.01 1.00E-06
Silica Mica 200 ft to 600 ft 0.0075 0.0075 0.0075 0.005 1.00E-06
Schist
>600 ft 0.001 0.001 0.001 0.005 1.00E-06
<200ft 0.01 0.01 0.01 0.01 1.00E-06
Schist Marble 200 ft to 600 ft 0.0075 1 0.0075 0.0075 0.005 1 1.00E-06
>600 ft 0.001 0.001 0.001 0.005 1.00E-06
<200ft 0.001 0.001 0.001 0.01 1.00E-06
Marble 200 ft to 600 ft 0.001 0.001 0.001 0.005 1.00E-06
>600 ft 0.001 0.001 0.001 0.005 1.00E-06
<200ft 0.008 0.008 0.008 0.01 1.00E-06
Phyllitic 200 ft to 600 ft 0.004 0.004 0.004 0.005 1.00E-06
Metasiltstone
>600 ft 0.001 0.001 0.001 0.005 1.00E-06
<200ft 0.01 0.01 0.01 0.01 1.00E-06
External 200 ft to 600 ft 0.001 0.001 1 0.001 0.005 1.00E-06
Bedrock
>600 ft 0.001 0.001 1 0.001 0.005 1.00E-06
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Hydrogeological Study and Groundwater Modeling-Kings Mountain Mining Project Page 61
Table 5-2: Comparison of the Modeled and Measured Values of Hydraulic Conductivity
Field Measured/Estimated Hydraulic Modeled Hydraulic
Conductivity(ft/d) Conductivity(ft/d)by
Hydrogeologic Unit Depth
Number 200 ft to >600
of Tests Minimum Maximum Geomean <200ft I ft ft
Overburden 22 0.0035 10.7000 0.1080 4
Saprolite 22 0.0035 10.7000 0.1080 0.09
Weathered Bedrock 22 0.0035 10.7000 0.1080 0.4
Shear Contact(Southeast) 4 0.0676 0.4760 0.2370 0.2 0.2 0.001
Shear Contact(Northwest) 0 3.94E-06 1.6961 0.0113 0.2 0.2 0.001
Shear Zone Units 72 3.94E-06 10.6821 0.0437 0.05 0.01 0.001
Muscovite Schist(West) 2 0.0018 0.0020 0.0019 0.005 0.001 0.001
Silica Mica Schist 7 0.0154 0.5650 0.0621 0.01 0.0075 0.001
Schist Marble 4 9.18E-04 0.0094 0.0020 0.01 0.0075 0.001
Marble 14 1.23E-04 0.0605 0.0019 0.001
Phyllite 1 3 0.1550 2.2500 0.5500 0.008 0.004 0.001
External Bedrock 1 4 1 0.0351 0.2680 0.1350 0.01 0.001 0.001
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l
31�bLs
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Hydrogeological Study and Groundwater Modeling-Kings Mountain Mining Project Page 63
A Proposed Pit Outline A'
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Overburden Surficial Deposits Shear Zone Units Bedrock(101Q00) Marble Bedrock 100-200
Saprelite Surficial Deposits Shear Zone Units Bedrock(200-600) Marble Bedrock(20D-640}
Weathered Bedrock Surficial De posts Shear Zone Units Bedrock(640-104R) Marble Bedrock(60L�1000)
-ransitionZone Surficial Deposits liea Schist Bedrock(10o-200) Ph Ilite Bedrock 100-200
ShearContact(southeastern) Bednxk(10D-10DD) Silica Mica Schist Bedrock(200-600) Ph Ilite Bedrock 20D-640
ShearContact(Northwestern) Bednxk(10D-10DD) Silica Mica Schist Bedrock(600-1000) Phyllite Bedrock(500-100)}
Muscovite Schist(West) Bedrock(103-206)
Muscovite Schist West Bedrock 20D- Schist Marble Bedrock(1 k �00-200) External Bedrock Bedroc (10200}
Muscovite Schist(West) Bedrock(50D-lODD) Schist Marble Bedrock(20D-600) External Bedrock Bedrock(200 600}
iSchisl Marble I Bedrock(600-1000) External Bedrock I Bedrock Go41000
srk consulting Graundwal M Modeling Study far Kings
Mountain Project
A L�3 E A R L E Simulated Hydrogeologic Units in Cross-
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Figure 5-6: Simulated Hydrogeologic Units in Cross-Section A-A'
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SRK Consulting(U.S.), Inc.
Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page 64
B Proposed Pit Outline By
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Overburden Surfirial Deposits Shear Zone Units Bedrock(100200) Marble Bedrock 1C10-204
Saprolite Surfirial Deposits Shear Zone Units Bedrock(20�600) Marble Bedrock(2C10-504)
Weathered Bed rock Surfirial Deposit=_ Shear Zone Units Bedrock(60�10Oa) Marble Bedrock(6Oa1000)
TransitionZene Surfirial Deposits SIIICa MICA sChl5t Bedrock(100 2a0) Ph I lit
e Bedrock 100 20a
shearContact(southeastern) Bedrock(1Da1ODD)
ShearContart(Northwestern) Bedrock(1DD 1DDD) Silica Mrca Schrst Bedrock(200-600) Ph Ilite Bedrock 209-600
Muscovite Schist(West) Bedrock(1DaZ00) SiliC3 Mrca schist Bedrock(60a-1a00) Phyllite Bedrock(500-1000)
Muscovite Schist(West) Bedrock(ZDD-5W) Schist Marble Bedrock(100-200) External Bedrock Bedrock(100-200)
Muscovite Schist(West) Bedrock(6Do-1ODD) Schist Marble Bedrock(20 -600) External Bedrock Bedrock(200-500)
Schist MarbleBedrock(600 1000) External Bedrock Bedrock 60a1044
srk consul 41 r g Groundwater Modeling Study for Kings
Mountain Project
ed Hydrogeologic Units in Cross-
oknw�r e,^ rev art=a era ie®uen rare Albenls rle Corporation
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Figure 5-7: Simulated Hydrogeologic Units in Cross Section B-B'
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Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page 65
Numerical Model Section A-A' Numerical Model Section B-B'
H X e 62
I
Leapfrog Model Section A-A' Leapfrog Model Section B-B'
N A' a s'
r
Nate: Lithology legend found on Figure 5-7 and 5-8�srk C Q n s u I}`I n C Groundwater Mlodeling Study for Kings
�� Mountain Project
Comparison of Simulated ors.Leapfrog
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Figure 5-8: Comparison of Simulated vs. Leapfrog Cross-Sections
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5.2.2 Simulation of Recharge to Groundwater System
Recharge from precipitation was applied to the first saturated grid layer (the uppermost active layer)
at different rates based on precipitation data(PRISM, 2020)and extent of urbanization; recharge rates
were also adjusted during the calibration process to appropriately simulate baseflow in streams. The
recharge applied in the model was 16-20% of MAP over natural areas, and 12% of mean annual
precipitation over urbanized areas. In total, ten different recharge zones were assigned, with recharge
rates varying from 5.39 to 7.63 in/yr, as shown in Figure 5-9.
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l
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Figure 5-9: Simulated Recharge Zones
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Additional recharge zones were assigned to represent mine facilities during future mining and post-
mining conditions. Mine facilities consist of waste rock dumps RSF-A and RSF-X southwest of the pit.
Different recharge rates were assigned to the various facilities, depending on expected hydraulic
parameters of the material as well as cover and lining designs. Recharge rates for on-site facilities
were extracted from Surface Water model (SRK, 2023b). Recharge zones representing mine facilities
and simulated recharge rates for mining and post-mining conditions on proposed mine facilities are
shown in Figure 5-10.
Variations in recharge rate across the mine facilities are related to: 1) engineering differences among
the proposed facilities;2)variations in initial saturation of material;and 3)vertical hydraulic conductivity
of the materials. Of the proposed facilities, WRD X is covered, and WRD-A is open. The waste rock is
assumed to be deposited dry will not transmit much precipitation through to the soils initially. Finally,
the vertical hydraulic conductivity waste rock will depend on the material type. Further details are
available in SRK, 2023b.
Simulated Recharge Rate on Facilities
40
35
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Mountainn Project
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L 1�/1 r'(L �� ��w Mine Facilities Albemarle Corporation
.SRK.2023 05,2023 :>.FIGURE 5-10
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Figure 5-10: Simulated Recharge Zones Representing Mine Facilities
5.2.3 Simulation of Groundwater Discharge into Surface Water Bodies
Groundwater discharge to the streams was simulated by a combination of the Stream Flow Routing
(SFR) package (Prudic, 1989) and drain boundary conditions (DRN package). The SFR package
allows for simulating major stream channels, including interaction between surface water and
groundwater and surface flow between adjacent grid cells. The DRN package was used to model
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minor stream tributaries and control the water table elevation relative to ground surface topography.
The use of the drain package in this way is a common approach in regional models to simulate runoff,
even in high-elevation areas. Water removed by the drains in these locations represents the
conversion of infiltration to runoff. To simulate surface-water bodies, a total of 1,529 SFR and 1,314
drain cells were used within the uppermost layer of the model.The following creeks and their tributaries
were incorporated into the model using a combination of SFR and DRN boundary conditions:
• Kings Creek
• Long Creek
• Buffalo Creek
• Crowders and South Crowders Creeks
• Clark Fork
These creeks are shown in Figure 5-4. The total number of simulated creeks, forks, and branches
within the model domain was 29.
The following assumptions were used in simulation of stream boundary conditions:
• Streambed thickness— 1 ft
• Hydraulic conductivity of streambed sediments— 1 ft
• Stream width — 10 ft
• Stream length calculated by intersection of grid cells and stream polylines.
• Stream roughness—0.037
Drain boundary conditions were used to simulate groundwater outflow to minor creek tributaries.These
were assigned based on topographic map under the assumption that the water level in a tributary is 5
ft below average land surface elevation within a given grid cell. Unrestricted conductance of 10,000
ft2/d was assigned to drain cells to simulate these minor tributaries.
As shown in Figure 5-10, proposed mine facilities (WRDs and TSFs) intercept channels which act as
gaining streams. SRK assumed that the facilities will be engineered so that water would continue to
drain under these facilities, rather than mound. Therefore,SFR cells representing channels intersected
by proposed mine facilities were left unchanged for the future mining and post-mining simulations,
though it is understood that these cells represent underdrain systems rather than natural stream
channels in the predictive simulations.
Initial iterations of the predictive post-mining model indicated that the proposed pit lake will eventually
spill over into the surface water system.Therefore, an additional SFR segment was added to the post-
mining model to simulate the routing of proposed pit lake water to Kings Creek (Figure 5-11).
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5.2.4 Simulation of Historic Mining
The mining of the open pit was simulated using drain cells, which extract groundwater from the model
depending on water-level elevation and conductance. Flow to the drain cells was calculated according
to:
f CL x(H — Zd),if H > Zd
Qd 0,if H < Zd (1)
Where:
• Qd= inflow to drain cell (ft3/d)
• H = hydraulic head (ft)
• Zd= elevation of bottom of pit(ft)
• CL= conductance of drain cell (ft2/d)
A total number of 3,652 drain cells were used to simulate the excavation of the historical pit. The
locations of the drain cells used to simulate excavation of the pit and the simulated elevations of the
bottom over time are shown in Figure 5-11. The conductance was assigned to be 1,000 ft2/d for all
drain cells simulating pit excavation. Since historical pit plans during the period from 1955 through
1993 were not available to SRK, excavation of the historical pit during this 39-year period was
simulated by proportionally interpolating from pre-mining topography to the current pit shell.
Simulated Pit Bottom Elevation
950
900
850
800
c
0
750
w
W
700 -
Legend
Drain Polygons Simulating Historic Pit
650
Model Polygons —
Proposed Pit
600
1954 1964 1974 1984 1994
v srk Consulting Groundwater Modeling for Kings
Mountainn Project
A\A L B E M A R L E Simulation of Historic Pit Excavation oR.Albemarle Corporation
SOURCE 5RK,2023 1 1,—05i2023 NO FIGURE 5-11
FILENAME SRKJOE ER USPR000576
Figure 5-11: Simulation of Historic Pit Excavation
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5.2.5 Simulation of Pit Lake Recovery
Upon cessation of historical pit excavation by the end of 1993, the open pit began to fill with water.
The rate at which the pit fills, and the ultimate depth and stage of the pit lake, depends on the pit lake
water balance. The pit lake water balance comprises of the various flow components into and out of
the lake.
The historical water balance for the Kings Mountain pit lake can be expressed as:
Apit lake volume = P + Roff-pit+ Roff-up + QGW in— E—QGW out—Qpump—QSW out (2)
Where:
P =the inflow from direct precipitation falling on the lake surface
Roff-up= the inflow from runoff from up-gradient drainages
Roff-pit = the inflow from pit-wall runoff (the fraction of precipitation falling on the pitwalls that
ultimately reaches the pit-lake)
QGW in =the groundwater inflow to the pit-lake
E = the open water evaporation from the pit-lake surface based on a modified pan evaporation
rate
QGW out= the outflow of groundwater from the pit-lake
Qpump= pumping rate from pit lake (occasionally occurred)
Qsw out= surface-water outflow
Apit lake volume = the change in the pit-lake storage.
Assumption used for simulation of historical pit lake include:
• Pit lake precipitation at a rate of 48 in/yr
• Pit lake evaporation at a rate of 42 in/yr
• Pit wall runoff at a rate of 30% of precipitation (14.4 in/yr)
• No runoff from up-gradient drainages
Both historical and future pit lake infilling were simulated by using the LAK3 Package (Merritt and
Konikow, 2000). Figure 5-12 shows the components of the conceptual model for the historical and
future pit lakes.
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Si Consulting(U.S.), Inc.
Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page 72
Conceptual Model for Historic KM Pit Lake
Up-gradient
Direct Precipitation(P) I Runoff
W V V Y V Runoff into �^
the pit
Evaporation[E} {Ron art} WaterTa6le
Water Withdrawal T7$
(a) [Qpump] � S
-Water Table- -- "� Groundwater
Inflouv(Qc,v; l
Groundwater �✓
Outflovd
Conceptual Model for Proposed KM Pit Lake
Up-gradient
Direct
lPrecipitation(P) I Runoff(R„�ep]
V W W L V Runoff into
the pit Water Table
Evaporation(F) _ ------
lRo f-aft Pit Lake Spillover into
1b1
Surface Water Body
f 5W—)
-WatefTaMe Groundwater
Groundwater �_�
Inflow(Q,
Outflow(4Gw-0j
Figure 5-12: Conceptual Model for Historical (a) and Proposed (b) Kings Mountain Pit Lake
To match the end of pit excavation inflows with groundwater inflows at the initial phase of the pit lake
infilling, a conductance value of 0.1 ft2/d was assigned to the pit lake cells. All surface water
components and estimated pumping rates from the pit lake were taken from the GoldSim Model
(SRK, 2023b). The simulated stage-volume and stage-area relationships for the historic pit lake are
shown in Figure 5-13 and Figure 5-13b, respectively.
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SRK Consulting(U.S.), Inc.
Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page 73
(a) (b)
900 900
850 850
E800 E 800
ra m
ago 750 0 750
b to
700 700
650 650
600 600
0 100,000,000 200,000,000 300,000,000 0 1,000,000 2,000,000 3,000,000
Lake Volume(ft3) Lake Area(sq ft)
srk consulting Groundwater ModelingStudyforKings
Simulated StageNolume(a)and Mountain Project
AA L B E M A R L E —Y 7o--E StagelArea(b) oa Albemarle Corporation
,ACE SRK.2023 a„E 0512021 Relationships for Historical Pit Lake FIGURE 5-13
rR PL v 11a . .aUSPR000576
Figure 5-13: Simulated Stage/Volume (a) and Stage/Area (b) Relationships for the Historical
Pit Lake
5.3 Measured Water Levels and Pit Inflow and Transient Model
Calibration
5.3.1 Calibration to Historical Pit Lake Inflow and Water Levels
The simulated passive inflow to the historical Kings Mountain pit is shown in Figure 5-14. The model
simulates groundwater inflow at the end of the legacy mining (year 1993) of about 130 gpm, which is
slightly below the estimated flow range of about 150-200 gpm.
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SRK Consulting(U.S.), Inc.
Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page 74
140 950
120 900
100 ............................................... 850
CUI
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,0 60 750
m
40 700
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0 - 600
1954 1962 1970 1978 1986 1994
Date
Groundwater Inflow During Mining(gpm) - Simulated Pit Bottom Elevation
srk consul}.1 ng Groundwater Modeling Study for Kings
Mountain Project
AALBEMARLE Simulated Inflow to Historical Open Pit oA,Albemarle Corporation
u-11 11,21123 ,E W2023 FIGURE 5-14
E LA,G,g,_E,,I anun_TR_PLR r27,x1,, USPlxgoo576
Figure 5-14: Simulated Inflow to Historical Open Pit
Figure 5-15 compares simulated pit lake elevation with observed stages while Figure 5-16 compares
simulated groundwater inflow to the pit lake with estimated values using GoldSim surface water pit
lake model (SRK, 2023b). In SRK's opinion, the model very well reproduces the pit lake stage during
historical pit lake infilling and reasonably approximates groundwater inflow into the pit lake within
estimated inflow ranges.
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SRK Consulting(U.S.), Inc.
Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page 75
850
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800
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750
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0
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650
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1993 1997 2001 2005 2009 2013 2017 2021 2025
• Historical Pit Lake Elevation,Minimum Estimate • Historical Pit Lake Elevation,Maximum Estimate —Simulated Pit Lake Elevation
srk consulting Groundwater Modeling Study for Kings
Mountain Project
A A L B E M A R L E —� 1 ��� E Comparison of Simulated versus Measured
Historical Pit Lake Elevation oaAlbemarle Corporation
aRK 2023 ,E 0sr2023 FIGURE 5-15
a�e_Evaiuetion_rR_ara_,7-1. Ea.USPR000576
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Figure 5-15: Comparison of Simulated versus Measured Historic Pit Lake Elevation
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SRnConuvmng(U.S.), Inc.
Hydrogeological Study Groundwater
250
200
150
CL
50
-Groundwater Inflow During Lake Recovery Simulated byGroundwater Model(gpm)
Groundwater Inflow During Lake Recovery Simulated by Surface Water Model(SRIK,2023b,gpm)
Groundwater Inflow During Mining Simulated byGroundwater Model(gpm)
Groundwater Modeling StudyforKings
srk Consulting :..parison of Groundwater Inflow into Mountain Project
AALBEMARLE Historical Pit Lake Simulated by Albemarle Corporation
......SRK 2021 r"r 05(2023 Groundwater and Surface Water Models FIGURE 5-16
Figure 5-16: Comparison mf Groundwater Inflow into Historical Fit Lake Simulated by
Groundwater and Surface Water Models
5'3'2 Calibration to Baseflow
Flow measurements for two |oonUono on South Creek (near the Kings Mountain mina) and for two
|oouUono near the edges of the regional model boundary are available. BaeeOow analysis was
performed for these locations, and modeled flow in the streams was compared to estimated baseflow.
The groundwater model does not simulate surface water responses to precipitation events, but rather
it simulates bauef|ow resulting from groundwater discharge. Simulated baoeUowo compare favorably
with estimated baeoflowm, as shown in Table 5'3. Locations for all stations are shown in Figuro3'4.
and detailed locations for Stations 3 through 8 are displayed in Figure3'1. Stations 3 and 5 are
approximate measurements and are not used for calibration.
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SRK Consulting(U.S.), Inc.
Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page 77
Table 5-3: Comparison of Measured and Simulated Baseflows
Location Location Measured Flow Simulated Flow
Number Description (gpm) (gpm) Error
Kings Creek-
1 Outflow 6,340 6,235 -1.7%
Long Creek-
2 Outflow 6,974 7,351 5.4%
Kings Creek
Downstream
3 of Weir#3' 117 332 n/a
South Creek
4 upstream end 70 67 -4.6%
South Creek
Northern end
5 of TSF' 125- 148 86 n/a
Kings Creek
U/S of Weir
6 #3 178 178 -0.1%
1 This measurement is approximate and not reliable for calibration
5.3.3 Calibration to Current Groundwater Levels
Calibration of the transiently simulated water levels to measured values in the vicinity of the existing
pit lake is illustrated by a quality line plot (shown in Figure 5-17), where measured water levels are
compared with simulated values. The water level calibration statistics are also shown in Table 5-4,
indicating an acceptable scaled root mean square error (RMSE) of 8.3% (typically, a model is
considered well-calibrated if the scaled RMSE is below 10%). The distribution of water level residuals
and simulated water table contours for current conditions is shown in Figure 5-18. Complete
comparison between simulated and measured water levels is shown in Appendix B.
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Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page 78
1,000
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Observed
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v srk consulting Groundwater Modeling Study for Kings
Mountain Project
A A L B E M A R L E a. °� E Comparison of Simulated versus Measured
Water Levels by duality Line Alhemarle Corporation
.cz SRK,2023 ,E.05r2o2a FIGURE No FIGURE 5.17
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Figure 5-17: Comparison of Simulated versus Measured Water Levels by Quality Line
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SRK Consulting(U.S.), Inc.
Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page 79
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Figure 5-18: Distribution of Water Level Residuals for Simulation of Current Conditions
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SRK Consulting(U.S.), Inc.
Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page 80
To better define the hydraulic parameters of the two Shear Contact zones, the model was preliminarily
verified to pumping test data observed during the testing of KMMW-002 (the northwest contact) and
RTKM22-382 (the southeast contact).
Comparisons between simulated and measured drawdown are shown in Figure 5-19 and Figure 5-20
for pumping tests in KMMW-002 and RTKM22-382, respectively. These monitoring wells were
selected for short-term simulations of pumping tests because they represent properties of the Shear
Contacts, which are permeable features in the vicinity of the proposed pit.
0
20
40
• i
0 60 '
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80
100 ............-. _,-,,,,..,,
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—Simulated • Measured
Simulated pumping rate: 150 GPM
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or Kings
Mountainn Project
AALBEMARLE r Model Calibration of KMMW-002Pumping
�� Test Albemarle Corporation
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Me KMMW-003 KMMW002xlsx sa.USPR000576
Figure 5-19: Model Calibration of KMMW-002 Pumping Test
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Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page 81
0 s 140
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• Measured -Simulated ......•••Pumping Rate
-Y srk consu lti ng M G oundwat Modeling study for Kings
Mountain Project
_I A L B E M A R L E � Model Calibration of RTKM22-382 Pumping
� Test o Albemarle Corporation
�.SRK,2023 C512023 -_ FIGURE 5-20
Me.RTKM-382 obsV55lm.x sx Ea:USPROODS78
Figure 5-20: Model Calibration of RTKM22-382 Pumping Test
5.3.4 Summary of Model Calibration, Simulated Water Table and Groundwater
Budget
SRK is of the opinion that the 3-D numerical regional groundwater flow model is reasonably calibrated
to legacy and existing hydrogeological data and reproduces:
• Groundwater inflow into the historical pit at the end of excavation.
• Historical pit lake recovery and groundwater inflows into the pit lake.
• Measured ground water levels in monitoring wells under the current conditions.
• The most important pumping tests target hydraulic parameters of the Shear Contacts - the
most permeable hydrogeological features at the site-which would control groundwater inflow
during future pit excavation.
Figure 5-18 shows the simulated water table at the current conditions (end of December 2022) and
direction of groundwater flow. Table 5-4 shows the simulated groundwater budget for the current
conditions.
5.4 Simulation of Proposed Open Pit
Excavation of future open pit was simulated by drain cells, which extract groundwater from the model
depending on water-level elevation and leakance(described by Equation 1)similarly to historic mining.
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Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page 82
A total number of 5,594 drain cells were used to simulate the excavation of the proposed pit. The
locations of the drain cells used to simulate excavation of the pit and the simulated elevations of the
bottom of the pit over time are shown in Figure 5-21. A conductance of 1,000 ft2/d was assigned to all
drain cells simulating pit excavation. The elevations assigned to drain cells varied in time based on the
yearly pit shells provided to SRK by Albemarle.
Simulated Pit Bottom Elevation
700
650
600 -
-550
k $
500
�I v
450
0
1 400
M 350
Legend
300
Drain Polygons Simulating Proposed Pit
Model Polygons 250
Proposed Pit 200
0 1 2 3 4 5 6 7 8 9 10
Years Since Start of Mining
� Groundwat,Mo&IinpStudy for Kings
srk consulting
1� Mountain Project
Locations of Drain Polygons and
AA L B EMA RLE Simulated Proposed Pit Bottom Elevation Alb—rle Corporation
R .SRK,2023 re09"23 Through Time FIGURE5-21
n5 PRODOB76
Figure 5-21: Locations of Drain Polygons and Simulated Proposed Pit Bottom Elevation
Through Time
Dewatering of the existing pit lake prior to mining was simulated using the LAK3 subroutine.
Dewatering was simulated by withdrawal from the pit lake at a fixed rate of 2,000 gpm until the lake
was dry; continued withdrawal removed any additional water added so the pit was dry until excavation
began. Dewatering the current pit lake required approximately 1.7 years of simulated pumping;
extraction continued to keep the pit dry for an additional 0.3 years until excavation begins (totaling
approximately two years of dewatering). The model assumed that the nominal rate of 2,000 gpm was
maintained throughout the dewatering phase; dewatering may require more time if the nominal rate is
not maintained.
5.5 Simulation of Partial Pit Backfilling
The current pit plan considers partial pit backfilling to an elevation of 570 ft amsl. For backfilling
simulations, drain cells used to simulate open pit excavation in the predictive mining model, and that
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SRK Consulting(U.S.), Inc.
Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page 83
were below elevation of 570 ft amsl, were deactivated. Hydraulic parameters of the model elements
simulating original rock units were assigned new values under the following assumptions:
• Hydraulic conductivity (Kh) of the backfill set to 10 ft/day (isotropic conditions)
• Specific yield (Sy) of the backfill set to 0.15
• Instantaneous backfilling after end of the mining
5.6 Simulation of Proposed Pit Lake Infilling
Drain cells used to simulate open pit excavation at the end of the mining, above top of the backfilling
at elevation above 570 ft amsl, were converted to pit lake boundary condition using the LAK3
subroutine (similar to the historical pit lake).
Pit lake infilling during postmining conditions was simulated using Equation (2) under following
assumptions:
• Pit lake precipitation at a rate of 48 in/yr.
• Pit lake evaporation at a rate of 42 in/yr.
• Pit wall runoff rate at 30% of precipitation (14.4 in/yr).
• Time-variable runoff from up-gradient drainages, ranging from 9.4 gpm to 37.5 gpm with long-
term rate of 26.8 gpm(up-gradient runoff values were extracted from the surface water model).
• Spillover elevation of 850 ft amsl (location of pit lake spillover is shown in Figure 5-21).
• Conductance of pit lake bottom of 0.1 ft2/d (this value was obtained by matching end of pit
excavation inflows with groundwater inflows at the initial phase of the pit lake infilling for no
backfill scenario).
The simulated vs. engineered stage-volume and stage-area relationships for the pit lake above the top
of backfill at elevation of 570 ft amsl are shown in Figure 5-22 and Figure 5-22b.
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SRK Consulting(U.S.), Inc.
Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page 84
(a) (b)
1100 1100
1000 1000
H 900 a 900
m
-------------------- ---------------- ------------------------------- ------
to 800 m 800
30 Y Y
700 J 700
600 600
........................... ..................... .......................f...........{.......
....�...
500 500
0 500 1,000 1,500 2,000 2,500 0 1 2 3 4 5 6 7
Lake Volume(in millions of cubic feet) Lake Area(in millions of square feet)
—Lake Stage-Volume Relationship —Lake Stage-Area Relationship
•••Top of Backfill Top of Backf ill
-----Spillover Elevation -----Spillover Elevation
m0r Srlll( consulting Groundwater Modeling Study for Kings
Simulated StageNolume(a)and Mountain Project
J�` I� T { D T 1-1- StagelArea(b) =o=.:Albemarle Corporation
11(-]j� lVl('-11\f� q SRK.2n23 a E.os�202a Relationship for Proposed Pit Lake -_-„�.FIGURE 5.22
F LE­.FutureLake SVA.xlsx eR USPR000576
Figure 5-22: Simulated Stage/Volume (a) and Stage/Area (b) Relationship for the Proposed Pit
Lake
Table 5-4: Statistics of Model Calibration to Measured Water Levels
Residual Mean ft -1.8
Absolute Residual Mean ft 21.3
Residual Std. Deviation ft 30.1
Sum of Squares ft2 299604
RMS Error(ft) 30.1
Min. Residual ft -184.5
Max. Residual ft 105.1
Number of Observations 254
Range in Observations ft 385.8
Scaled Residual Std. Deviation 7.8%
Scaled Absolute Residual Mean 5.5%
Scaled RIMS Error 7.8%
Scaled Residual Mean -0.5%
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Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page 85
6 Predictions of Future Mining
6.1 Predicted Passive Inflow to Open Pit
The predictive simulations assumed that the current pit lake will be dewatered by pumping at a rate of
2,000 gpm over approximately 1.7 years. The dry pit will be maintained by pumping as necessary for
another 0.3 years (total of 2 years of dewatering); the proposed pit will then be excavated to an
elevation of 285 ft amsl over the course of 9.5 years.
The annual-average predicted groundwater inflow to the proposed pit is shown in Figure 6-1 and
demonstrates:
1. Gradually increasing inflow from 100 gpm to 150 gpm during the first four years of excavation,
then increasing to 260 gpm in year 5 when the pit widens and deepens. The intersection of
the wider pit with the water table allows greater groundwater inflow into the pit.
2. The inflow decreases in years 5 through 7 due to the drainage of storage and deepening of
the pit into less conductive units during those years.
3. The inflow increases again in year 8 when the pit deepens to a final depth of 285 feet, and
reaches an average annual inflow of about 270 gpm at the end of mining.
Changes in groundwater inflow to the pit lake result from a combination of factors: as the pit is
excavated, the head difference between the pit and the surrounding groundwater system increases,
resulting in increased flow to the pit. However, as the pit deepens, the excavated material is lower in
permeability, and therefore provides more resistance to groundwater flow.The peak inflow thus occurs
when the head difference is high and rock with relatively high hydraulic conductivity has recently been
excavated.
6.2 Predicted Water Table and Its Changes
The model simulates the lowering of the water table in the pit area and drawdown propagation as result
of the dewatering by in-pit sumps. Figure 6-2 shows the predicted water table and direction of
groundwater flow at the end of the mining. Figure 6-3 shows predicted changes in water table
compared to the current conditions at the end of mining.
The model predicts that 5-ft drawdown contour associated with in-pit dewatering will propagate from
the center of proposed pit:
• 0.37 miles to the northwest
• 0.28 miles to the southeast
• 0.47 miles to the northeast and
• 0.97 miles to the southwest
Overall, the cone of drawdown (CoD) remains fairly close to the proposed pit due to the relatively low
hydraulic conductivity of the rock material around the pit and is mostly confined to the area associated
with legacy mining. The wetlands overlying predicted drawdown propagation are related to legacy
mining and are not natural. While drawdown is expected to propagate to confirmed and suspected
wells identified in the hydro census, these are unlikely to be significantly affected due to the small
amount of drawdown expected. Surface water bodies impacted by the CoD are predominantly already
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SRK Consulting(U.S.), Inc.
Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page 86
altered by legacy mining, with flows mostly controlled by the current Kings Mountain pit and the
operation of the Martina Marietta quarry lake.
The propagation of drawdown is controlled by:
• Shape of the Shear Zone and the Shear Contact zones (the most permeable units)
• Presence of low-permeability Muscovite Schist and Marble (the low K units)
• NE fault — not simulated directly by the model but limits the northeast extent of the
southeastern Shear Contact
Figure 6-3 shows a rising water table around proposed WRD-A, due to increased recharge under
WRD-A during mining.
6.3 Predicted Change in Groundwater Budget
Predicted groundwater budget at the end of the mining and comparison to current conditions are
shown in Table 6-1.
The model simulates that major sources of groundwater inflow to the proposed pit are:
• Depletion of groundwater storage and
• Capture of recharge that would previously have been routed to streams, thereby reducing the
amount of baseflow in streams
The model predicts change in groundwater flow to creeks at the end of mining as follows:
• Kings Creek (within model domain) increased by 32 gpm (or 0.5%), owing to the increase
recharge through the waste rock dump.
• Long Creek(within model domain) no change
South Creek, in the facility area, will be affected by operations as well; recharge from the WRD is
routed almost entirely to South Creek and from there into Kings Creek.
Simulated groundwater inflow to the proposed pit will depend on the material excavated and on the
difference in heads between the pit and the surrounding groundwater system. Predicted inflow will
vary over time based on these factors, as shown in Figure 6-1.
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700 700
600 600
500 I————I Soo
'--—————— ——— — —
I
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200 200
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100 {1a 100
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Years Since Start of Mining
—Average annual groundwater inflow to open pit —— Pit bottom elevation
=O-srk consulting G—dwatW Modeling Study for ings
MoonGin Project
A A L B E M A R L E eM1°°° Predicted Groundwater Inflow into Proposed
Pit Albemarle c°rporana
wce.GRK.2123 0IM2023 FIGURE 6-1
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Note:The increase in pit lake inflows at points(1)and(2)is related to the deepening and widening of the pit.The intersection of the wider pit with
the nearby water table allows greater groundwater inflow into the pit.The decline in groundwater inflow from years 4 to 8(3)is explained by the
drainage of storage and deepening of the pit into less conductive units during those years.Figure 1-4 shows the pit development in 3-D.
Figure 6-1: Predicted Groundwater Inflow into Proposed Pit
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Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page 88
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Figure 6-2: Predicted Water Table and Direction of Groundwater Flow at End of Mining
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Figure 6-3: Predicted Water Table Changes at End of Mining Compared to Current Conditions
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Table 6-1: Predicted Groundwater Budget for End of Mining
End of Change
Legacy Pit End of from
Components Lake Future Current
Recovery Mining Conditions
(Current to End of
Conditions) Mining
Recharge from Precipitation/Mine Facilities 48,130 48,230 -100
Groundwater Inflow to Model Boundary(CHEAD) - - 0
Recharge from Streams (SFR) 201 201 0
Kings Creek and Tributaries 79 79 0
Inflows Long Creek and Tributaries 19 19 0
Other Creeks and Tributaries 103 103 0
Depletion of Groundwater Storage 0 68 -68
Pit Lake Outflow into Groundwater(LAK3) 0 - 0
Total Inflow 48,331 48,499 -168
Groundwater Outflow from Model Domain (CHEAD) 1,138 1,138 0
Southwestern 403 403 0
Southern 187 187 0
Southeastern 120 120 0
Northeastern 428 428 0
Groundwater discharge to the Streams(SFR+Drain) 46,928 46,962 -34
Outflows Kings Creek and Tributaries 6,235 6,267 -31
Long Creek and Tributaries 7,351 7,351 0
Other Creeks and Tributaries 33,342 33,344 -3
Groundwater Inflow to Kings Mountain Pit(Drain) - 218 -218
Groundwater Inflow to Martin Marietta Pit(Drain) 174 174 0
Groundwater Inflow into Pit Lake(LAK3) 68 - 68
Pit Lake Spillover into Surface Water(Drain) - i - 0
Replenishment of Groundwater Storage 23 6 16
Notes:
Negative change indicates an increase of flow from current conditions.
Flow rates are in gpm.
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7 Predictions of Post-Mining Conditions
The conceptual model of the pit lake during post-mining conditions is shown in Figure 5-12b in
Section 5 above. Predictions of the post-mining conditions include:
• Partial pit backfilling and pit lake infilling
• Water level changes within groundwater system
• Predicted changes in groundwater budget
• Pit lake water balance components as input for pit lake chemistry modeling
These predictions are described below.
7.1 Predicted Pit Lake Infilling
The predicted pit lake elevation trend and components of the pit lake water balance are shown in
Figure 7-1 The model simulates that:
• Partial backfill with top elevation of 570 ft amsl will be saturated in approximately 3 years after
the end of mining.
• Pit lake elevation will increase in time and reach spillover elevation of 850 ft amsl in 56 years
after the end of mining.
• Groundwater inflow into the pit lake will gradually decrease from 270 gpm from the end of the
mining to 63 gpm after 68 years of recovery and stay constant in time after that.
• Pit lake outflow into the groundwater system (mainly to the southeast from the pit lake) will
start in year 46 of infilling and will reach a flux of about 27 gpm.
• Pit lake spillover rate to surface water will reach 198 gpm.
The components of the pit lake water balance for long-term post-mining conditions are summarized in
Table 7-1.
Table 7-1: Predicted Water Balance of Future Pit Lake for Long-term Post-Mining Conditions
Component Rate pm
Inflow
Precipitation 301
Pitwall runoff 16
Runoff from up-gradient drainages 29
Groundwater 63
Total 409
Outflow
Evaporation 184
Groundwater 27
Spillover 198
Total 409
Detailed simulated pit lake water balance as input for pit lake chemistry model is presented in
Appendix C.
7.2 Predicted Water Level Changes
The model simulates groundwater recovery during post-mining conditions as the pit lake infills.
However, during the earliest phase of recovery drawdown continues to propagate away from the pit
due to the low permeability nature of the hydrogeological units in proximity to the pit.
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Figure 7-2 presents the maximum 5-ft drawdown cone extent for the water table and in layer 6 of the
model (approximately 300 ft below ground surface). Drawdown in deeper hydrogeologic units is
delayed due to low permeability.
Figure 7-2 demonstrates:
• Maximum water table drawdown extent propagation from the center of the pit:
0 0.52 miles to the northwest
o 0.29 miles to the southeast
o 0.53 miles to the northeast
0 1.22 miles to the southwest
• Locations of 4 different hypothetical monitoring points to illustrate water table changes during
both mining and post-mining conditions. Simulated hydrographs for these hypothetical
monitoring locations are provided in Figure 7-4
Predicted maximum water table drawdown extent will occur 15 years after the end of mining at point
1, 11 years after the end of mining at point 2, 19 years after the end of mining at point 3, and 30 years
after the end of mining at point 4.
The water table drawdown cone is divided into two separate lobes due to the location of WRD-A.
Recharge under WRD-A is reduced over the long term, lowering the water table under the footprint.
The maximum extent of the CoD does not occur vertically at the water table, but rather at depth. At a
depth of approximately 300 feet (model layer 6), which is the maximum depth of existing community
wells, the model simulates a combined cone of drawdown that is 12% larger than the water table CoD
(Figure 7-2).
Predicted long-term post-mining water table and direction of groundwater flow are shown in Figure 7-4.
Figure 7-5 illustrates the effect of forming the larger pit lake and changes in recharge to the
groundwater system during long-term post-mining compared to the current conditions.
7.3 Predicted Changes in Groundwater Budget
The predicted changes in groundwater budget components during long term post-mining conditions
compared to the current and end of mining conditions are shown in Table 7-2.
The model predicts the following long-term conditions:
• Pit lake spillover at the rate of about 198 gpm
• Pit lake outflow into groundwater system at the rate of about 35 gpm groundwater outflow
• Groundwater discharge to:
o Kings Creek (within model domain)—increased 2 gpm (or less than 0.1%)
o Long Creek (within model domain)—no change
7.4 Predicted Changes in Baseflow
The predicted baseflow in Kings Creek,Long Creek, and South Creek are shown in Figure 7-6
indicating:
• Maximum reduction in Kings Creek of 88 gpm (1.4 %) in 18 years after the end of mining
• No changes in baseflow of Long Creek
• Maximum reduction in South Creek of 6 gpm (8.9%) in 22 years after the end of mining
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7.5 Predicted Pit Lake Water Balance Components as Input for Pit
Lake Chemistry Modeling
The predictions of pit lake infilling were used to simulate inputs for pit lake water chemistry modeling.
They are summarized in Table 7-2. It is important for the pit lake water chemistry modeling to be able
to separate the amount of water coming into the pit from groundwater and surface water, and
potentially to further subdivide the groundwater based on the geologic unit it traveled through before
arriving in the pit.
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—Runoff from Upcatchment Basin(gpm) —Pit Lake Elevation ---Groundwater Level Before Pit Lake Forms
srlc consulting Groundwater Modeling Study tar Kings
Predicted Future Pit Lake Elevation and Mountain Project
A&A L S E M A R L E wNOY ` "`"`°°`°° Components of Pit Lake Water Balance in roe Albemarle Corporation
­sRK,2023 09'2023 Time FIGURE 7-1
­s .=-1:a -a USPRO00576
Figure 7-1: Predicted Future Pit Lake Elevation and Components of Pit Lake Water Balance in
Time
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Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page 95
Observation Point 1 Observation Point 2
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srk consulting Groundwater Modeling Study for Kings
Mountain Project
A A L B E M A R L E Hydrographs of Water Table Change at
_�cF�,•ry sr.ct RE`✓E1ti3t)B":VO IEs IEo FOR Albemarle Corporation
Monitoring Points Shawn in Figure 7-2
sc_pcE SRK,2023 DUE 09+2023 FIGJ EKo:FIGURE 7-3
FILE NAME.Munitering"'ellS_FM_v2S6.xlsx SR. X3 Wh1EER USPR000576
Figure 7-3: Hydrographs of Water Table Change at Monitoring Points Shown in Figure 7-2
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SRK Consulting(U.S.), Inc.
Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page 96
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Figure 7-4: Predicted Water Table and Direction of Groundwater Flow for Long-Term Post-Mining Conditions
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and Post-Mining Conditions
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Table 7-2: Predicted Groundwater Budget for Long-term Post-Mining Conditions
Change
End of from
Legacy Pit Long-Term Current
Components Lake Post- Conditions
Recovery) Mining to Long-
(Current Conditions Term Post-
Conditions) Mining
Conditions
Recharge from Precipitation/Mine Facilities 48,130 48,029 101
Groundwater Inflow to Model Boundary CHEAD) - 0
Recharge from Streams (SFR) 201 215 -14
Kings Creek and Tributaries 79 93 -14
Inflows Long Creek and Tributaries 19 19 0
Other Creeks and Tributaries 103 103 0
Depletion of Groundwater Storage 0 2 -2
Pit Lake Outflow into Groundwater LAK3 0 35 -35
Total Inflow 48,331 48,281 50
Groundwater Outflow from Model Domain (CHEAD) 1,138 1,176 -38
Southwestern 403 439 -36
Southern 187 187 0
Southeastern 120 122 -2
Northeastern 428 428 0
Groundwater discharge to the Streams(SFR+Drain) 46,928 46,875 53
Outflows Kings Creek and Tributaries 6,235 6,186 49
Long Creek and Tributaries 7,351 7,351 0
Other Creeks and Tributaries 33,342 33,338 4
Groundwater Inflow to Kings Mountain Pit Drain - - 0
Groundwater Inflow to Martin Marietta Pit Drain 174 178 -4
Groundwater Inflow into Pit Lake LAK3 68 52 16
Replenishment of Groundwater Storage 23 0 23
Total Outflow 48,331 48,281 50
Notes:
• Negative change indicates an increase from current conditions
• Flow rates are shown in gpm
7.6 Predicted Impacts to Water Resources
Open pit excavation and associated dewatering will alter the groundwater level around the open pit.
Lowering the groundwater level to the pit bottom at the pit area will create a groundwater level change
called the CoD. The CoD will impact springs, nearby community wells, and wetlands; impacts are
analyzed using the calibrated numerical model.
To assess impacts to water resources, the largest extent of the model-produced CoD (5-ft contour)
was overlaid with water resources data within the 0.5-mile buffer zone around the project fence line.
Planned project unit boundaries are also incorporated into this analysis to evaluate whether the
construction activities and/or waste deposition (WRD or TSF) directly impact the water resources.
Figure 7-2 shows the locations of seeps/springs, wetlands and community wells near the project.
Seep/Springs: A total of 16 seep/springs were detected within the 0.5-mile buffer of the project fence
line, and 14 of them were located within the fenced area. A total of 4 springs fall in to 5 ft contour of
the maximum extent of the CoD. However, those springs within the 5 ft CoD will also be under
proposed mine facilities; none of the seep/springs will be solely impacted by groundwater level
changes.
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Wetlands: Wetlands data obtained from the SWCA (Section 3.5)was overlayed with proposed mine
facilities and maximum extent of CoD contours as well. A total of 2 wetland water bodies are located
within the 5-ft contour of the maximum extent of the CoD. As can be seen from the Figure 7-2, all the
wetlands located within the CoD will be also impacted from the project infrastructure.
Community Wells: As outlined in Section 3.6, the AECOM hydrocensus surveys yielded two distinct
sets of information pertaining to the data on community wells. These sets include confirmed wells,
which are identified through actual well construction records, and suspected wells, which are identified
through various remote sensing data source as satellite imagery and Google Street View surveys.
Through spatial analyses, it has been determined that there are 126 suspected wells located within a
buffer zone of 0.5 miles from the project's Fence Line. Among these, 27 wells fall within the project's
fence area and will be directly affected by the infrastructure development.
Furthermore, in the southwestern region, there are 2 wells situated outside the project's Fence area
that may experience the effects of changes in groundwater. These changes are expected due to a
decrease in recharge from the waste rock.
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8 Hydrogeological Uncertainties and Results of
Sensitivity Analysis
8.1 Uncertainties in Understanding Hydrogeological Conditions and
Purpose of Sensitivity Analysis
Analysis of field data and results of numerical modeling indicate hydrogeological uncertainties as
follows:
• Specific storage and specific yield. Storage parameters are difficult to measure using short
term field testing and frequently cannot be estimated with precision for a given hydrogeologic
unit.
• Hydraulic conductivity of the Muscovite Schist. The model has been calibrated with relatively
low hydraulic conductivity for this unit,which 1) limits the amount of groundwater that can flow
into the proposed pit, and 2) limits the extent of the cone of drawdown to the west of the
proposed pit. Limited test data are available indicating uncertainty in hydraulic conductivity
values of the Muscovite Schist and their lateral and vertical distributions.
• Hydraulic conductivity of the Marble. The model simulates the Marble to the east of the pit as
a barrier to hydraulic flow due to significant difference between water levels in the Kings
Mountain pit lake and the Kings Mountain pit lake to the Martin Marietta quarry lake. There is
a scarcity of test data related to hydraulic conductivity values in the Marble unit, which
introduces uncertainty regarding both their lateral and vertical distributions. The presumed
extremely low hydraulic conductivity within this unit constrains the reach of the cone of
drawdown to the eastern side of the Kings Mountain pit.
• Hydraulic conductivity of the Shear Contact zones. The Shear Contact zones are defined as
conduits for groundwater flow due to being relatively higher in hydraulic conductivity than the
surrounding units, and therefore the simulated cone of drawdown propagates along them.
Hydraulic conductivity values and their distribution with depth have some uncertainties
influencing the model predictions.
• Hydraulic conductivity of the Shear Zone. The Shear Zone is a major hydrogeological unit
which will be excavated by the proposed pit. Completed hydrogeologic testing of this unit
indicates significant variability in lateral and vertical distributions of hydraulic conductivity
values as shown in Table 4-1 causing uncertainties in results of predictions (especially in pit
inflow estimates).
• Existence of Transition Zone. Conflicting data regarding the existence of a potentially highly
permeable transition zone beneath the weathered bedrock was obtained from the field.
Spinner log results indicated that most of the flow in some holes came from the bedrock below
the weathered bedrock. The model does not simulate a transition zone, but if it does exist it
will significantly impact pit inflow and maximum drawdown predictions.
• Hydrogeological role of the EW-01 fault, shown on Figure 2-6. This fault has not been
incorporated into numerical model since packer tests indicated that this fault may not be
important hydrogeologically. However, the geologic block model shows an offset in geologic
units along this fault, which may indicate that the fault is important.
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While the numerical groundwater model is well-calibrated to several types of data, uncertainty in the
predictions remains. To understand the importance of these uncertainties on the results of prediction
additional sensitivity analysis was conducted.
Sensitivity analysis involves varying specific model parameters and determining the impact of the
changes on the model results. If changing a parameter results in a large change in the predicted
values, the model is said to be sensitive to that parameter. Parameters to which the model is sensitive
can then be targeted for further investigation to reduce the overall uncertainty surrounding the
predictions made by the model. Additionally, sensitivity analysis can preliminarily indicate potential
variations in the predictive parameters (preliminary estimates are due to use of uncalibrated models).
The following sensitivity scenarios(runs were completed)sources of hydrogeological uncertainty were
addressed:
• Variation of specific yield of the hydrogeological units by a factor of 2
• Variation of specific storage of the hydrogeological units by a factor of 5
• Increase of hydraulic conductivity of the Muscovite Schist by a factor of 10
• Increase of hydraulic conductivity of marble by a factor of 10
• Variation of hydraulic conductivity of the northern Shear Contact zone by a factor of 2
• Variation of hydraulic conductivity of the southern Shear Contact zone by a factor of 2
• Variation of hydraulic conductivity of the Shear Zone by a factor of 3
• Incorporation of Transition Zone as highly permeable features with hydraulic conductivity of
0.5 ft/day. Simulated by replacing bedrock and weathered bedrock units in model layer 4 with
transition zone unit
• Incorporation of EW-01 fault as a hydraulic barrier(K=0.001 ft/day)
• Incorporation of EW-01 fault as a permeable conduit (K=0.2 ft/day)
8.2 Results of Sensitivity Analysis of Passive Pit Inflow
Results of the sensitivity analysis of predicted passive pit inflow during mining are shown in Table 8-1
and Figure 8-1. The highest maximum pit inflow of 336 gpm, and the highest end of mining pit inflow
of 334 gpm, was simulated during sensitivity scenario 1, in which specific yield for all zones was
increased by a factor of 2.This is 25%greater than the maximum pit inflow and end of mining pit inflow
for the Base Case. The lowest maximum pit inflow and end of mining pit inflow of 229 gpm and 229
gpm, respectively,was simulated during sensitivity scenario 2, in which specific yield for all zones was
decreased by a factor of 2. This is 15% less than the maximum pit inflow for the Base Case. These
results demonstrate the importance of the storage parameters on transient flow results. The amount
of water that can be released from storage is a pivotal factor governing the maximum passive pit inflow.
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Table 8-1: Results of Sensitivity Analysis of Predicted Pit Inflow
Predicted Pit Inflow pm
Sensitivity Description Maximum %Change End of %Change
Scenario Pit Inflow from Base Mining from Base
Case Case
0 Base Case 268 --- 268 ---
1 Increase specific yield parameters by 336 25% 334 25%
factor of 2
2 Decrease specific yield by factor of 2 229 -15% 229 -15%
3 Increase specific storage parameters by 277 3% 277 3%
factor of 5
4 Decrease specific storage parameters by 263 -2% 263 -2%
factor of 5
5 Increase of K of Muscovite Schist by 280 5% 280 5%
factor of 10
6 Increase of K of Marble by factor of 10 272 1% 272 1%
7 Increase K of Southeastern Shear 271 1% 271 1%
Contact by factor of 2
8 Decrease of Southeastern Shear Contact 264 -2% 264 -2%
by factor of 2
9 Increase K of Northwestern Shear 274 2% 274 2%
Contact by factor of 2
10 Decrease K of Northwestern Shear 262 -2% 262 -2%
Contact by factor of 2
11 Increase K of Shear Zone by factor of 3 299 12% 290 8%
12 Decrease K of Shear Zone by factor of 3 251 -6% 251 -6%
13 Incorporate Transition Zone as Highly 301 12% 301 12%
Permeable Feature K=0.5 ft/da
14 Simulation of EW-01 Fault as a Barrier 239 -11% 235 -12%
K=0.001 ft/da
15 Simulation of EW-01 Fault as a Conduit 330 23% 324 21%
K=0.2 ft/da
8.3 Results of Sensitivity Analysis of Maximum Drawdown Extent
The results of sensitivity analysis on predicted maximum extent of the 5-ft water table CoD are
summarized in Table 8-2 and shown in Figure 8-2. As can be seen on Figure 8-2, the shape of the
drawdown cone and its extent are greatly influenced by the hydraulic conductivity distribution in the
model and the assumptions used in the conceptual model. The maximum extent of water table CoD
varied from 1.35 to 1.56 miles from the center of the pit. The maximum drawdown extent of 1.6 miles
from the center of the pit for sensitivity scenario 5, in which the hydraulic conductivity of the muscovite
schist was increased by a factor of 10, to a value of 0.05 ft/day, is 14% greater than the maximum
drawdown extent for the base case. Under the base case, the low hydraulic conductivity of the
muscovite schist prevents the westward expansion of the drawdown cone. The maximum drawdown
extent of 1.35 miles from the center of the pit for sensitivity scenario 10, in which the hydraulic
conductivity of the shear contact zone (northwest)was decreased by a factor of 2, is 7% less than the
maximum drawdown extent for the base case. The relatively low K of the shear contact zone prevents
the drawdown cone from extending as far out in this case relative to the base case.
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Hydrogeological Study and Groundwater Modeling-Kings Mountain Mining Project Page 104
Table 8-2: Results of Sensitivity Analysis of Maximum Water Table Drawdown Extent
Sensitivity Distance of Predicted 5-ft Drawdown Cone from
Run Description Proposed Pit Center(mi)
Northwest Southwest Northeast Southeast
0 Base Case 0.52 1.22 0.53 0.29
1 Increase specific yield parameters by 0.53 1.18 0.54 0.28
factor of 2
2 Decrease specific yield by factor of 2 0.6 1.26 0.53 0.28
3 Increase specific storage parameters 0.53 1.22 0.54 0.28
by factor of 5
4 Decrease specific storage 0.53 1.22 0.54 0.28
parameters by factor of 5
5 Increase of K of Muscovite Schist by 0.6 1.2 0.55 0.28
factor of 10
6 Increase of K of Marble by factor of 0.54 1.22 1.23 0.28
10
7 Increase K of Shear 0.54 1.22 0.55 0.28
Contact Southeast by factor of 2
8 Decrease of Shear Contact 0.53 1.22 0.53 0.28
Southeast by factor of 2
9 Increase K of Shear Contact 0.54 1.21 0.53 0.28
Northwest by factor of 2
10 Decrease K of Shear Contact 0.52 1.23 0.53 0.28
Northwest by factor of 2
11 Increase K of Shear Zone by factor of 0.51 1.22 0.6 0.3
3
12 Decrease K of Shear Zone by factor 0.56 1.23 0.52 0.29
of 3
13 Incorporate Transition Zone as Highly 0.78 1.38 0.59 0.35
Permeable Feature K=0.5 ft/da
14 Simulation of Fault with low K 0.78 1.38 0.48 0.35
barrier K=0.001 ft/da
15 Simulation of NE Fault as conduit(K= 1.05 1.38 1.23 0.35
0.2 ft/da
8.4 Sensitivity Analysis of Pit Lake Infilling and Spillover Outflow
Results of the sensitivity analysis on pit lake infilling and spillover outflow are summarized in Table 8-3
and shown in
Figure 8-3. The predicted time to reach the pit lake spillover elevation after proposed mining is
complete varied from 73 to 78 years. The maximum spillover rate for all of the sensitivity runs was
unchanged from the base case, since the overall water balance of the model was not varied during
sensitivity analysis (recharge remained the same).At the long timescales considered by the predictive
model,the pit lake comes to steady state and the spillover rate is unaffected by sensitivity parameters.
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Table 8-3: Results of Sensitivity Analysis of Time of Pit Lake Infilling
Time to Reach Pit Lake Pit Lake
Sensitivity Description Spillover Elevation Spillover Rate
Scenario (years since end of (gpm)
Rpm)
0 Base Case 55 198
1 Increase specific yield parameters by factor of 2 56 196
2 Decrease specific yield by factor of 2 55 199
3 Increase specific storage parameters by factor of 64 195
5
4 Decrease specific storage parameters by factor 53 197
of 5
5 Increase of K of Muscovite Schist by factor of 10 53 199
6 Increase of K of Marble by factor of 10 55 198
7 Increase K of Southeastern Shear Contact by 54 199
factor of 2
8 Decrease of Southeastern Shear Contact by 55 198
factor of 2
9 Increase K of Northwestern Shear Contact by 54 201
factor of 2
10 Decrease K of Northwestern Shear Contact by 55 197
factor of 2
11 Increase K of Shear Zone by factor of 3 52 205
12 Decrease K of Shear Zone by factor of 3 56 195
13 Incorporate Transition Zone as Highly Permeable 52 205
Feature K=0.5 ft/da
14 Simulation of EW-01 Fault as a Barrier(K=0.001 59 188
ft/d a
15 Simulation of EW-01 Fault as a Conduit(K=0.2 49 183
ft/da
8.5 Sensitivity Analysis of Reduction of Groundwater Inflow to the
Creeks
Results of the sensitivity analysis on reduction of groundwater flow to creeks are shown in Table 8-4
and Figure 8-4. The maximum reduction in baseflow in Kings Creek of 175 gpm for sensitivity scenario
13, in which the transition zone is incorporated, is 22% greater than the reduction in baseflow for the
base case. This is because the drawdown cone for the transition zone scenario is more extensive. The
maximum reduction in baseflow in Kings Creek of 139 gpm for the sensitivity scenario 12, in which the
shear zone K is reduced is 3% less than the reduction in baseflow in Kings Creek for the base case.
The impact to Kings Creek is reduced in this scenario because the reduction in shear zone K allows
the pit drawdown to pull less water from the creek.
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Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page 106
Table 8-4: Results of Sensitivity Analysis of Kings Creek Baseflow Reduction
Sensitivity Maximum Reduction of
Scenario Description Baseflow in Kings
Creek m
0 Base Case 144
1 Increasespecific yield parameters by factor of 2 145
2 1 Decreasespecific yield by factor of 2 153
3 Increase specific storage parameters by factor of 5 142
4 Decrease specific storage parameters by factor of 5 144
5 Increase of K of Muscovite Schist by factor of 10 149
6 Increase of K of Marble by factor of 10 148
7 Increase K of Southeastern Shear Contact by factor of 2 146
8 Decrease of Southeastern Shear Contact by factor of 2 142
9 Increase K of Northwestern Shear Contact by factor of 2 146
10 Decrease K of Northwestern Shear Contact by factor of 2 143
11 Increase K of Shear Zone by factor of 3 153
12 Decrease K of Shear Zone by factor of 3 139
13 Incorporate Transition Zone as Highly Permeable Feature 175
K=0.5 ft/da
14 Simulation of EW-01 Fault as a Barrier(K=0.001 ft/day) 142
15 Simulation of EW-01 Fault as a Conduit(K=0.2 ft/day) 155
700 700
i
6a0 600
�6a9e Cage
500 500 —1
L � ——-2
400 5[enario1:340 400 n ___q
gpm C 5
o
s rr
3a0 300 -7 Y
I_
200 I____ 200
---12
Pr:bottom E l—fion
0 0
0 1 _ 3 4 5 6 7 S 1 10 11
Years Since Start of Mining
srk co In 5 U I tl ng M Grcundwat Modeling Study For sings
Mountain Project
A A L B E M A R L E - .w Reruns of Sensitivity Analysis of
Passivea Pitt Inflow Albemarle Corporation
i -9RK.2023 OEV2023 FIGURE 8-1
rr_E roue en:a SPR000576
Figure 8-1: Results of Sensitivity Analysis of Passive Pit Inflow
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SRK Consulting(U.S.), Inc.
Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page 107
1
a
rr�
1'
i
Leqend
Gam. All Send[--ty S(eQfios —srk� y "�.."'w•w..c�"i.•
c. AALBEMARLE
rmoo�i Gu � �.r�na Kixns wouanw wwwo cao.�tt ••�•:"�
® Omi.utawux
Figure 8-2: Results of Sensitivity Analysis of Maximum Drawdown Extent
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SRK Consulting(U.S.), Inc.
Hydrogeological Study and Groundwater Modeling-Kings Mountain Mining Project Page 108
Pit Lake Elevation Pit Lake Spillover Rate
900 —
900
230
350 260
240
BOB 220
200 _
150 ---- - -- --
R 1S0
i 150
700
w p 140
� s
� 550
1zo
100
500 ao
60
550 - 40
20
500
0 50 100 15O zoo u
0 5o 100 150 NO
Years Since End of Mining
Years Since End of Mining
Base Cam 1 2 —9 ---4 5 —6 7 - - -8 —9 ---10 —11 ---12
=0F=srk consulting G tMraaaeP nyr°.Kings
Moun}ai.P-roject
AALBEMARLE •°°° °°°.w Resu Its ofSensitivityAnalysisof
In
Pit Lake Infilling and Spillover Outflow rn:Rlhemarle Caporalim
SRK.2023 -.0912023 FIGURE"
FLE onus Pm—LakePeckage.,ks u:i1SPRD00576
Figure 8-3: Results of Sensitivity Analysis of Pit Lake Infilling and Spillover Outflow
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Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page 109
640C
6300
Base Case
6200 � +• ___2
—3
6100 _4
_ 5
C
6
G —7
-__g
SE Cx — _9
-10
580C — —11
---12
13
570C —
—14
---15
560C
295 49S 69S n'3S 19.5
Years Sinm Start of Mining
Y srk consulting
L.Io s YicU }I I'lJ-y G-und—t-H.&Iog Studyf-Kings
LL Resu lts of Sensitivity Analysis of Mountain Project
AA L P E MA R LE Reduction of Groundwater Inflow to Albemarle C.rp—tion
oe.ERK.2023 1 ,tonr2023 Kings Creek FIGURE 3-4
FLED E: ..0G P R00057G
an v[cV�n=�e5 n n Hpxgaog.,'
Figure 8-4: Results of Sensitivity Analysis of Reduction of Groundwater Inflow to the Creeks
8.6 Climate Section Evaluation for Long Term Closure Predictions
Climate change scenarios were evaluated as part of the surface water modeling (SRK, 2023b). A
variety of scenarios were evaluated on a deterministic and probabilistic basis; full details are available
in SRK (2023b).
8.7 Simulation of Martin Marietta Pit and Its Potential impact
Predictions
At this phase of the project, there is limited data regarding Martin Marietta's remaining reserves and
the future plans for utilizing the pit. As per present observations, the numerical model has simulated
the MM water elevation with drains positioned at an elevation of 620 ft amsl. It's important to note that
the water management strategy for the MM pit might undergo alterations in the future, potentially
influencing the operational and closure aspects of the KM open pit. Therefore, additional
communication and analysis of uncertainties will be necessary to address future considerations related
to the MM pit and cumulative impacts.
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Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Page 110
9 Conclusions
The hydrogeological study conducted for KMMP involved various crucial components to ensure a
comprehensive understanding of the groundwater system and its interaction with the mining activities.
The study encompassed geological data analysis, the development of a 3-D Leapfrog geological
model, and comprehensive field hydrogeological investigations. One of the key outcomes of the study
was the development of CHM, which served as the foundation for subsequent analyses. The CHM,
combined with the 3-D Leapfrog geological model, formed the basis for the development of a 3-D
NGWM.
The NGWM was constructed with MODFLOW-USG finite-difference code (unstructured version),
underwent rigorous calibration to ensure its accuracy and reliability in predicting various groundwater
parameters. Through the calibration process, the NGWM successfully captured important aspects,
including groundwater inflow to the historic pit, the recovery of the historic pit lake, currently
monitored water levels, and the representation of the two long-term pumping tests conducted within
critical lithologies. Additionally, baseflow measurements were considered as calibration targets to
enhance the model's accuracy. Water level calibration concluded with RMS error less than 10% and
baseflow error in the range of 1-5% which deemed acceptable considering the industry standards.
The NGWM was utilized to make predictions regarding future mining conditions. These predictions
included pit inflow and drawdown propagation, as well as the saturation of backfill, pit lake infilling, and
pit lake outflow into the groundwater system.
Furthermore, the model assessed the potential spillover of the pit lake into nearby surface-water
bodies, analyzed maximum drawdown propagation, and evaluated the impact on groundwater users
such as nearby community wells, springs and wetlands.
The following list provides the key outcomes of the modeling work for the Base Case predictions and
sensitivity analysis:
• Pit inflow rates during the mine were estimated in the range of from 100 to 270 gpm under the
Base Case. The maximum pit inflow ranges from 230 to 340 gpm for Sensitivity Scenarios.
• Maximum water table drawdown extends for the Base Case from 0.29 miles to the southeast
to 0.52-0.53 miles to the northwest and northeast and 1.22 miles to the southwest,
respectively. The maximum extent will be formed at different times during interval from about
11 to 30 years after mining ended. Sensitivity analysis indicates that maximum water table
drawdown extent can be from 0.28 to mi to 1.26 mi.
• Maximum reduction in baseflow in Kings Creek within model domain by 88 gpm (1.4 %) in 18
years of post-mining. The maximum reduction of baseflow ranges from 60 to 90 gpm for
Sensitivity scenarios. The model does not predict any changes in baseflow in Long Creek.
Pit lake recovery analysis suggested that:
• Partially backfill with top elevation of 570 ft amsl will be saturated in 3.1 years under Base
Case with variation between 2.2 and 7.4 years.
• Pit lake elevation will increase in time and reach spillover elevation of 850 ft amsl in 56 years
after end of mining under Base Case with variation between 48 and 64 years for Sensitivity
Scenarios).
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• Groundwater inflow into the pit lake will gradually decrease from 270 gpm from the end of the
mining to 63 gpm after 68 years of recovery for Base Case and stay constant in time after that.
• Pit lake outflow into the groundwater system (mainly to the southeast from the pit lake) will
start in year 46 of infilling and will reach a flux of about 27 gpm under Base Case.
• Pit lake spillover rate as surface water outflow will reach 198 gpm.
The completed sensitivity analysis to address uncertainties and assess the robustness of the findings
indicates that most sensitive model parameters are:
• Specific yield for pit inflow predictions
• K of Muscovite Schist for predictions of maximum drawdown extent
• Consideration of Transition Zone as highly permeable feature for baseflow reduction
The sensitivity analysis provided valuable insights into the reliability of the predictions and helped
identify areas where further data collection or refinement might be necessary.
In summary, the hydrogeological study successfully employed geological data analysis, field
investigations, and the development of a 3-D numerical groundwater model to comprehensively
understand and predict the interactions between mining activities and the groundwater system. The
findings of this study will provide crucial information for effective management and mitigation of
potential impacts on the groundwater system, ensuring sustainable mining practices and the protection
of water resources and associated ecosystems.
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10 References
Dewitz, J. (2021). National Land Cover Database (NLCD) 2019 Products [Data set]. U.S. Geological
Survey. https://doi.org/10.5066/P9KZCM54
Environmental Simulations, Inc. (ESI), (2020). Guide to Using Groundwater Vistas, version 8, code
documentation report. Reinholds, PA: Environmental Simulations, Inc.
Goldsmith, R., Milton, J., and Horton Jr., J. W., (1988). Geologic Map of the Charlotte 1* x 2*
Quadrangle, North Carolina and South Carolina: U.S. Geological Survey Miscellaneous
Investigations Map 1-1251-E, 1 sheet, 1:250,000 scale, 1988.
Horton Jr., J. W., (2008). Geologic Map of the Kings Mountain and Grover Quadrangles, Cleveland
and Gaston Counties, North Carolina, and Cherokee and York Counties, South Carolina: U.S.
Geological Survey Scientific Investigations Map 2981, 1 sheet, 1:24000 scale, 2008, with 15
p. pamphlet.
Leapfrog Regional Geological Model, SRK, 2022
Leapfrog Geological Refined Model, Albemarle, 2023.
Panday, Sorab, Langevin, C.D., Niswonger, R.G., Ibaraki, Motomu, and Hughes, J.D., 2013,
MODFLOW-USG version 1: An unstructured grid version of MODFLOW for simulating
groundwater flow and tightly coupled processes using a control volume finite-difference
formulation: U.S. Geological Survey Techniques and Methods, book 6, chap. A45, 66 p.,
https://doi.org/l 0.3133/tm6A45
PRISM Climate Group, Oregon State University, https://prism.oregonstate.edu, data created
December 2022, accessed April 2023.
SRK (2022). Development of Stage Discharge Relationship for South Creek Outlet Culverts and No.
3 Weir, technical memorandum prepared for Albemarle, September 27, 2022
SRK (2023a). Technical Report: Prefeasibility Study, Hydrogeologic Characterization Kings Mountain
Mining Project: report prepared for Albemarle, May 12, 2023
SRK(2023b). Technical Report 2022 Prefeasibility Study Surface Water:Water Balance Development
Report: report prepared for Albemarle, May 17, 2023.
SRK (2023c). Interim Geochemical Characterization Report for Kings Mountain Waste Rock, Ore and
Tailings, In Progress 2023.
U.S. Geological Survey (2006). Geologic Map of the Kings Mountain and Grover Quadrangles,
Cleveland and Gaston Counties, North Carolina, and Cherokee and York Counties, South
Carolina. Open File Report 2006-1238. Scale = 1:24,000
U.S. Geological Survey (2016) National Water Information System data available on the World Wide
Web (USGS Water Data for the Nation), accessed April 8 2022, at URL
wtaerdata.usgs.gov/nwis
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Disclaimer
The opinions expressed in this Report have been based on the information supplied to SRK Consulting
(U.S.), Inc. (SRK) by Albemarle Corporation (Albemarle). These opinions are provided in response to
a specific request from Albemarle to do so, and are subject to the contractual terms between SRK and
Albemarle. SRK has exercised all due care in reviewing the supplied information. Whilst SRK has
compared key supplied data with expected values, the accuracy of the results and conclusions from
the review are entirely reliant on the accuracy and completeness of the supplied data. SRK does not
accept responsibility for any errors or omissions in the supplied information and does not accept any
consequential liability arising from commercial decisions or actions resulting from them. Opinions
presented in this report apply to the site conditions and features as they existed at the time of SRK's
investigations, and those reasonably foreseeable. These opinions do not necessarily apply to
conditions and features that may arise after the date of this Report.
Copyright
This report is protected by copyright vested in SRK Consulting (U.S.), Inc. It may not be reproduced
or transmitted in any form or by any means whatsoever to any person without the written permission
of the copyright holder, SRK.
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List of Abbreviations
The US Customary System for weights & units has been used throughout report for site specific data
(unless otherwise stated). Rock mass classification schemes and geotechnical analysis figures may
be referenced in their original metric units.
Abbreviation Unit or Term
Albemarle Albemarle Corporation
amsl above mean sea level
CAD computer-aided design
CHEAD Constant head
CHM conceptual h dro eolo ical model
CoD Cone of drawdown
CVFD control-volume finite-difference
DWR Department of Water Resources
ft feet
GIS Geociraphic Information System
GPM gallons per minute
GSV Goo le Streetview
GSV Goo le Streetview
HGU h dro eolo unit
in/ r Inches per year
Kh Horizontal
KMMP Kin s Mountain Mining Project
KMSZ Kin s Mountain Shear Zone
Ky Vertical
MAP mean annual precipitation
mi miles
NGWM numerical groundwater model
SFR Stream Flow Routing
SRK SRK Consulting (U.S.), Inc.
Ss Specific Storage
SWAP Source Water Assessment Program
Sy Specific Yield
TSF tailings storage facility
VWP vibrating wire piezometers
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SRK Consulting(U.S.), Inc.
Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Appendices
Appendices
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SRK Consulting(U.S.), Inc.
Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Appendices
Appendix A: Hydrogeological Units per Model Layers
GEMS Ki ngsMou ntain_HydrogeoG W_Report_U SPR000576_Rev05.docx April 2024

O � N
1004 ft O T f
a 7a� Z
1s0 o M Grove cOurthO`SP Ashebrook y
a Park A
A Stubbs °
�a
�e
Z
Stony Poin
0
Q� 275
-IIn
land tonia
ings
Beaverh
74
Hoski
derly
on Blv
e
Cree
0 I o It
I
o: 1
l
1
I
— —G r
i
Shg6t Yorkmont Park
0
,en - - - - - - -- - - - - - - - -�° Lake
'Wylie
Rage 177 / 4�s
Ra a Sta
Beaver�y I o Steel Creek
3z1 0�Creek o Hebro
2 ft
Highway 557 -IT y Sc
°ry a`� Clover 5 AtyC\n Sharon
161 274 Lake Wylie
I � Drys��
221
5 I N'JhwaY 55 E 'OatP Ci r
a e ane North Carol—MIPS 32 ee
Legend Zone Number
srk co n s u I t i n n SIMULATED BEDROCK HYDROGEOLOGICAL
1 ■ 0 400 800 1200 Y .�� A L B E M A R L E UNITS IN LAYER f
REPORT:
2 DRAWN BY:PT REVIEWED BY:GE Groundwater Modeling Study for Kings
3- SOURCE:SRK 2023 DATE: 06.08.2023 KINGS MOUNTAIN MINING PROJECT Mountain Project
Feet FIGURE NO.: Appendix
48 FILE NAME:Appendix_KLayer1_0623 I SRK PROJECT...:USPR000576

O N
1004 ft Cr;
0) a
o ds, o
O Cherr o
AFF
rl \
-0 �� G
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M
a Park A
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% i
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o Stony Poin
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land onia
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e
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0
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-- -_ - - Qq d
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Yee ' -- - - - -- - _ _- - � Wylie o Prchd
Rage R l 177 /i a 4�s Sta
321 Begvercy4� \ Q Steel Creek creek Hebro
92 ft
Highway 557
y
I
°-* p`�� Clover S�ryp\n Sharon
<' 161 Lake Wylie y
274 0
5 1
321 Highway 55 E V O' Rd 7°
a e ane North Uarohna r ee
Legend Zone Number
z 16 26 SIMULATED BEDROCK HYDROGEOLOGICAL
- srk consulting UNITS IN LAYER 5
8� 19 36 400 $°° 1200 Jk A L B E M A R L E REPORT
Existing Open Pit 9 20 39 DRAWN BY:PT REVIEWED BY:GE Groundwater Modeling Study for Kings
,2 al 45 Mountain Project
Q Proposed Pit is 23 48 Feet souRCE:SRK2023 DATE: 06.08.2023 KINGS MOUNTAIN MINING PROJECT FIGURE NO.: Appendix
24 FILE NAME:A endix_KLa ef5_0623 SRK PROJECT NO.:USPR000576
21 PP Y
is Corporation Kings Mountain L:

N
1004 ft
I
o Z
o Cherr p _�
� o
P� -0 0
t50 o M \Grove CDurthD`Sc Ashebrook y
a Park A
A Stubbs o o `
a � I-
�a
0
Stony Poin
N
Q� 275
land onia
ings
Beaverbr
74
GaS.
Hoski
derly
B
onia
^oIV
PL p
e p A
Q
d 1
1
- - - -Gr
i Shgar Yorkmont Park
0
273 I o Rd
5 reen -- - -- _ �° Lake
i
Wylie o Prchd
R;agP Rd 4�s Sta
Begver�y o Steel Creek
92 ft Creek o Hebro
Highway 557 1 48
°ry Clover 1 S 1r O\n Sharon
61 Lake Wylie y
274
CatF, Ci r �C/S�
5 321 Highway 55 E VO' Rd /,°
a e ane North uaro in ee
Legend Zone Number
8 31
34 � srk consulting
13 32 SIMULATED BEDROCK HYDROGEOLOGICAL
� UNITS IN LAYER 10
14 400 $°° 1200
3kALBEMARLE
21 43 REPORT.
Existing Open Pit 22 4fi DRAWN BY:PT REVIEWED BY:GE Groundwater Modeling Study for Kings
z3 Mountain Project
Q Proposed Pit 24 Feet SOURCE:SRK2023 DATE: 06.08.2023 KINGS MOUNTAIN MINING PROJECT FIGURE NO.: Appendix
z5 FILE NAME:Appendix_KLayerl0_0623 SRKRO NO.:PJECT USP R000576
n

O N
1004 ft O ti
0 J V o 7� I
�o -o
t50 o M \Grove courrho`SP Ashebrook y
a Park A
A Stubbs o o `
a � I-
�a
�e
Z
Stony Poin
0 3
Q� 275
land onia
ings
Beaverb
74
Gas
ski
`-rly
onia on Blv
e�
e A
CreQ
oa �t
C l�
Q
_ I
Gr
i
Shg6r Yorkmont Park
0
Rd
s, reen Lake
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^ REPORT.
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44 Mountain Project
Q Proposed Pit so47 Feet SOURCE:SRK2023 DATE: 06.08.2023 KINGS MOUNTAIN MINING PROJECT FIGURE NO.: Appendix
310 FILE NAME:Appendix_KLayer15_0623 SRK PROJECT NO.:USP R000576

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ai 06.08.2023
FIGURE NO.: Appendix
Proposed Pit �, Feet
47 FILE NAME:Appendix_KLayer20_0623 SRK PROJECT NO.:USP R000576

SRK Consulting(U.S.), Inc.
Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Appendices
Appendix B: Comparison of Simulated and Measured Water
Levels
G E/MS Ki ngsMou ntain_HydrogeoG W_Report_U SPR000576_Rev05.docx April 2024

Groundwater Difference
Ground Measured Simulated
Eastingl Northing Bottom level l surface Dip Azimuth Top Screen groundwater groundwater between
Name Hole Type Screen measurement measured and
(ft) (ft) elevation (deg) (deg) (ft amsl) 2 level level
(ft amsl) (ft amsl) date m simulated
(year) (ft asl) (ft amsl) (ft)
DDKM17-001 Open Hole 1,296,710 543,584 798.5 65 1103 1798.5 224.8 2017 798.2 783.4 14.7
DDKM17-002 Open Hole 1,296,717 543,582 798.5 45 103 798.5 492.3 2017 796.1 783.4 12.6
DDKM17-003 Open Hole 1,296,856 543,777 799.9 45 103 799.9 479.6 2017 793.0 783.4 9.5
DDKM17-005 Open Hole 1,296,935 543,531 817.1 45 103 817.1 735.1 2017 812.0 783.4 28.6
DDKM17-006 Stub Well 1,297,159 543,503 817.2 45 103 774.4 704.7 2017 815.7 807.2 8.4
DDKM17-006 Stub Well 1,297,159 543,503 817.2 45 103 774.4 704.7 2018 817.6 811.3 6.3
DDKM17-006 Stub Well 1,297,159 543,503 817.2 45 103 774.4 704.7 2023 817.8 829.0 -11.2
DDKM17-007 Open Hole 1,297,031 543,735 802.3 45 103 802.3 586.6 2017 799.4 783.4 16.0
DDKM17-008 Open Hole 1,296,889 543,408 837.7 45 103 837.7 662.3 2017 830.4 dry n/a
DDKM17-009 Open Hole 1,296,909 543,760 801.5 45 283 801.5 -177.2 2017 793.4 783.4 10.0
DDKM17-010 Open Hole 1,296,290 543,389 797.9 55 103 797.9 136.0 2017 798.3 dry n/a
DDKM17-014 Open Hole 1,297,816 544,450 790.0 45 283 790.0 -699.2 2017 787.2 783.5 3.8
DDKM17-015 Open Hole 1,296,441 544,195 798.1 65 103 798.1 -187.9 2017 792.9 783.2 9.7
DDKM17-021 Stub Well 1,296,996 544,493 805.4 45 283 762.7 -641.4 2017 792.8 808.7 -15.9
DDKM17-021 Stub Well 1,296,996 544,493 805.4 45 283 762.7 -641.4 2018 794.7 814.0 -19.4
DDKM17-022 Open Hole 1,296,069 543,170 904.3 55 103 904.3 205.5 2017 883.2 850.5 32.7
DDKM17-026 Open Hole 1,295,582 543,285 923.7 55 103 923.7 -327.3 2017 907.9 881.6 26.3
DDKM17-029 Open Hole 1,296,447 544,194 798.0 45 103 798.0 123.0 2017 792.7 783.4 9.2
DDKM17-030 Open Hole 1,296,526 544,935 937.5 65 103 937.5 -326.2 2017 928.9 843.3 85.7
DDKM17-030 Open Hole 1,296,526 544,935 937.5 65 103 937.5 -326.2 2017 937.5 850.0 87.5
DDKM17-031 Open Hole 1,295,798 543,291 906.0 55 103 906.0 -99.1 2017 898.9 865.0 33.9
DDKM17-034 Open Hole 1,296,542 544,696 951.8 65 103 951.8 -258.4 2017 841.9 839.5 2.4
DDKM17-034 Open Hole 1,296,542 544,696 951.8 65 103 951.8 -258.4 2022 951.8 843.8 108.0
DDKM17-035 Open Hole 1,295,780 543,437 884.6 55 103 884.6 -296.5 2017 884.6 860.9 23.7
DDKM17-036 Open Hole 1,295,478 543,146 923.9 55 103 923.9 -154.1 2017 918.0 890.6 27.5
DDKM17-037 Open Hole 1,297,645 544,050 818.9 45 283 818.9 -620.7 2017 795.6 dry n/a
DDKM17-040 Open Hole 1,296,132 543,325 883.4 55 103 883.4 184.6 2017 877.1 dry n/a
DDKM17-042 Open Hole 1,296,451 544,471 972.8 65 103 972.8 -201.7 2017 941.1 842.0 99.1
DDKM17-043 Open Hole 1,295,922 543,397 883.4 55 103 883.4 23.4 2017 882.2 847.6 34.6
DDKM17-044 Open Hole 1,295,973 543,216 904.8 55 103 904.8 123.3 2017 888.5 854.5 33.9
DDKM17-045 Open Hole 1,295,685 543,080 921.5 55 103 921.5 5.1 2017 908.7 880.8 27.9
DDKM17-047 Open Hole 1,296,581 544,441 972.8 50 103 972.8 85.6 2017 802.3 795.8 6.5
DDKM17-049 Open Hole 1,296,441 544,194 797.6 45 283 797.6 304.7 2017 797.7 783.2 14.5
DDKM17-052 Stub Well 1,296,589 544,437 972.7 80 103 913.4 -400.4 2017 852.9 814.2 38.7
DDKM17-052 Stub Well 1,296,589 544,437 972.7 80 103 913.4 -400.4 2018 855.0 819.5 35.4
DDKM17-052 Stub Well 1,296,589 544,437 972.7 80 103 913.4 -400.4 2021 858.5 833.8 24.7
DDKM17-052 Stub Well 1,296,589 544,437 972.7 80 103 913.4 -400.4 2022 857.2 837.3 19.9
DDKM17-052 Stub Well 1,296,589 544,437 972.7 80 103 913.4 -400.4 2023 862.1 840.9 21.3
DDKM17-053 Open Hole 1,296,416 544,075 798.8 45 103 798.8 136.2 2017 787.7 783.4 4.3
DDKM17-057 Open Hole 1,296,478 543,340 796.3 55 103 796.3 408.9 2017 795.2 dry n/a
DDKM17-059 Open Hole 11,296,098 1544,106 952.9 50 103 952.9 -47.3 2017 894.0 dry n/a
DDKM17-063 10pen Hole 11,296,431 1543,852 1798.8 165 103 798.8 -23.3 12017 1787.3 1783.4 3.8
Page 1 of 10

Groundwater Difference
Ground Measured Simulated
Eastingl Northing Bottom level l surface Dip Azimuth Top Screen groundwater groundwater between
Name Hole Type Screen measurement measured and
(ft) (ft) elevation (deg) (deg) (ft amsl) 2 level level
(ft amsl) (ft amsl) date m simulated
(year) (ft asl) (ft amsl) (ft)
DDKM17-064 Open Hole 1,296,368 543,536 800.2 45 1103 1800.2 334.2 2017 798.6 783.4 15.2
DDKM17-067 Open Hole 1,295,997 542,804 898.8 55 103 898.8 272.6 2017 893.8 875.3 18.5
DDKM17-068 Open Hole 1,296,082 544,110 952.9 65 103 952.9 -266.2 2017 912.9 840.3 72.6
DDKM17-069 Open Hole 1,295,527 542,091 952.1 55 103 952.1 535.6 2017 917.7 889.8 27.9
DDKM17-070 Open Hole 1,296,216 542,711 904.8 55 103 904.8 -189.0 2017 884.8 870.1 14.7
DDKM17-073 Open Hole 1,295,388 542,116 934.6 55 103 934.6 340.8 2017 904.1 895.0 9.2
DDKM17-073 Open Hole 1,295,388 542,116 934.6 55 103 934.6 340.8 2022 909.2 895.3 13.9
DDKM17-074 Stub Well 1,297,446 543,871 801.8 45 283 759.3 -340.8 2017 788.9 788.2 0.7
DDKM17-074 Stub Well 1,297,446 543,871 801.8 45 283 759.3 -340.8 2018 791.5 795.7 -4.2
DDKM17-076 Open Hole 1,295,307 542,964 960.6 70 103 960.6 -359.0 2017 917.0 905.5 11.5
DDKM17-077 Stub Well 1,296,232 544,079 952.9 80 103 893.4 -565.6 2017 914.0 831.9 82.1
DDKM17-077 Stub Well 1,296,232 544,079 952.9 80 103 893.4 -565.6 2018 914.2 835.3 78.8
DDKM17-077 Stub Well 1,296,232 544,079 952.9 80 103 893.4 -565.6 2021 912.8 845.5 67.3
DDKM17-077 Stub Well 1,296,232 544,079 952.9 80 103 893.4 -565.6 2023 909.9 850.9 59.0
DDKM17-078 Open Hole 1,296,440 543,850 798.8 45 103 798.8 256.4 2017 787.1 783.4 3.6
DDKM17-080 Open Hole 1,295,263 542,155 936.8 45 283 936.8 319.7 2017 912.5 899.8 12.7
DDKM17-080 Open Hole 1,295,263 542,155 936.8 45 283 936.8 319.7 2022 905.1 900.1 5.1
DDKM17-082 Open Hole 1,296,416 543,858 798.7 45 283 798.7 291.7 2017 787.3 783.4 3.8
DDKM17-083 Open Hole 1,295,373 543,079 968.0 55 103 968.0 -93.6 2017 921.2 900.2 21.0
DDKM17-083 Open Hole 1,295,373 543,079 968.0 55 103 968.0 -93.6 2022 905.4 901.6 3.8
DDKM17-084 Open Hole 1,295,250 541,938 927.7 55 103 927.7 301.5 2017 901.5 896.2 5.3
DDKM17-086 Open Hole 1,296,364 543,537 800.2 45 283 800.2 230.9 2017 797.8 783.4 14.4
DDKM17-087 Open Hole 1,296,379 543,674 801.3 65 103 801.3 20.0 2017 795.4 783.4 12.0
DDKM17-089 Open Hole 1,295,874 543,850 927.9 50 103 927.9 -110.1 2017 915.8 848.0 67.8
DDKM17-090 Open Hole 1,295,366 543,079 967.9 70 103 967.9 -342.4 2017 920.0 900.8 19.2
DDKM17-090 Open Hole 1,295,366 543,079 967.9 70 103 967.9 -342.4 2022 898.9 902.2 -3.4
DDKM17-091 Open Hole 1,295,004 541,836 929.0 55 103 929.0 254.5 2017 898.9 899.7 -0.8
DDKM17-092 Open Hole 1,296,376 543,674 801.6 45 103 801.6 266.3 2017 795.1 783.4 11.6
DDKM17-094 Open Hole 1,296,724 543,456 795.2 45 103 795.2 411.2 2017 795.2 783.4 11.8
DDKM17-095 Open Hole 1,295,883 543,048 919.1 55 103 919.1 290.8 2017 900.2 871.5 28.8
DDKM17-096 Open Hole 1,295,867 543,852 927.8 65 103 927.8 -211.0 2017 916.5 848.8 67.8
DDKM17-097 Open Hole 1,295,473 542,710 920.9 55 103 920.9 230.2 2017 913.1 896.8 16.3
DDKM17-098 Open Hole 1,296,365 543,677 801.0 45 283 801.0 272.8 2017 798.2 783.4 14.7
DDKM17-099 Open Hole 1,295,075 541,972 938.0 55 103 938.0 247.3 2017 900.9 900.7 0.2
DDKM17-100 Open Hole 1,295,334 541,912 923.1 55 103 923.1 417.9 2017 898.1 892.7 5.4
DDKM17-101 Open Hole 1,296,337 543,470 798.4 45 283 798.4 287.2 2017 796.6 785.8 10.8
DDKM17-102 Open Hole 1,295,850 542,212 935.5 45 103 935.5 661.8 2017 892.1 875.1 16.9
DDKM17-103 Open Hole 1,295,957 543,980 942.3 50 103 942.3 -35.3 2017 917.9 843.2 74.7
DDKM17-104 Open Hole 1,295,648 542,631 922.8 55 103 922.8 95.1 2017 913.5 883.7 29.8
DDKM17-104 Open Hole 1,295,648 542,631 922.8 55 103 922.8 95.1 2022 913.4 885.4 28.0
DDKM17-105 Open Hole 11,296,079 1542,996 915.0 55 103 915.0 303.1 2017 872.5 860.9 111.6
DDKM17-106 10pen Hole 11,295,621 1543,195 1921.4 55 103 921.4 196.5 12017 1905.9 1881.2 124.7
Page 2 of 10

Groundwater Difference
Ground Measured Simulated
Eastingl Northing Bottom level l surface Dip Azimuth Top Screen groundwater groundwater between
Name Hole Type Screen measurement measured and
(ft) (ft) elevation (deg) (deg) (ft amsl) 2 level level
(ft amsl) (ft amsl) date m simulated
(year) (ft asl) (ft amsl) (ft)
DDKM17-107 Open Hole 1,295,367 541,719 917.8 55 1103 1917.8 589.9 2017 888.5 889.4 -0.9
DDKM17-108 Open Hole 1,295,569 542,695 940.6 55 103 940.6 -88.7 2017 916.0 885.0 31.0
DDKM17-108 Open Hole 1,295,569 542,695 940.6 55 103 940.6 -88.7 2022 913.0 886.9 26.1
DDKM17-110 Stub Well 1,295,343 541,708 914.6 55 103 865.5 417.4 2017 887.6 887.3 0.3
DDKM17-110 Stub Well 1,295,343 541,708 914.6 55 103 865.5 417.4 2018 896.4 887.4 9.0
DDKM17-110 Stub Well 1,295,343 541,708 914.6 55 103 865.5 417.4 2021 896.2 887.5 8.7
DDKM17-110 Stub Well 1,295,343 541,708 914.6 55 103 865.5 417.4 2022 894.8 887.5 7.3
DDKM17-110 Stub Well 1,295,343 541,708 914.6 55 103 865.5 417.4 2023 896.9 887.6 9.3
DDKM17-111 Open Hole 1,295,835 543,651 961.7 50 103 961.7 89.6 2017 865.8 850.4 15.4
DDKM17-112 Open Hole 1,295,454 542,511 948.7 55 103 948.7 -48.3 2017 917.7 889.4 28.2
DDKM17-112 Open Hole 1,295,454 542,511 948.7 55 103 948.7 -48.3 2022 908.1 890.6 17.5
DDKM17-113 Stub Well 1,295,769 541,840 916.2 55 103 833.7 655.5 2017 878.2 875.1 3.1
DDKM17-113 Stub Well 1,295,769 541,840 916.2 55 103 833.7 655.5 2018 875.8 875.2 0.6
DDKM17-113 Stub Well 1,295,769 541,840 916.2 55 103 833.7 655.5 2021 879.8 875.4 4.4
DDKM17-113 Stub Well 1,295,769 541,840 916.2 55 103 833.7 655.5 2022 879.1 875.5 3.6
DDKM17-114 Open Hole 1,296,332 542,924 944.3 55 103 944.3 643.7 2017 887.8 856.2 31.6
DDKM17-115 Open Hole 1,295,760 542,944 921.4 55 103 921.4 182.4 2017 902.9 881.1 21.8
DDKM17-116 Open Hole 1,295,585 541,860 904.2 55 103 904.2 634.5 2017 885.1 883.6 1.5
DDKM17-117 Stub Well 1,295,994 543,421 972.3 55 103 889.9 15.6 2017 886.8 841.7 45.0
DDKM17-117 Stub Well 1,295,994 543,421 972.3 55 103 889.9 15.6 2018 886.0 843.4 42.6
DDKM17-117 Stub Well 1,295,994 543,421 972.3 55 103 889.9 15.6 2021 883.3 850.1 33.2
DDKM17-117 Stub Well 1,295,994 543,421 972.3 55 103 889.9 15.6 2022 883.0 852.0 31.0
DDKM17-117 Stub Well 1,295,994 543,421 972.3 55 103 889.9 15.6 2023 888.7 854.1 34.5
DDKM17-118 Open Hole 1,295,796 542,442 940.3 55 103 940.3 281.9 2017 903.4 880.5 22.9
DDKM17-118 Open Hole 1,295,796 542,442 940.3 55 103 940.3 281.9 2022 902.4 881.7 20.8
DDKM17-119 Open Hole 1,296,499 543,089 927.6 55 103 927.6 651.6 2017 849.4 837.8 11.6
DDKM17-120 Open Hole 1,295,881 542,571 912.3 55 103 912.3 488.8 2017 895.7 879.9 15.8
DDKM17-121 Open Hole 1,295,580 542,467 947.2 55 103 947.2 208.2 2017 913.4 887.2 26.2
DDKM17-121 Open Hole 1,295,580 542,467 947.2 55 103 947.2 208.2 2022 903.5 888.3 15.2
DDKM17-122 Open Hole 1,295,452 541,902 903.0 55 103 903.0 585.9 2017 889.4 889.3 0.1
DDKM17-123 Open Hole 1,295,653 542,786 923.2 55 103 923.2 160.0 2017 906.6 888.0 18.6
DDKM17-124 Open Hole 1,295,575 543,111 921.8 55 103 921.8 809.6 2017 911.4 885.3 26.0
DDKM17-125 Open Hole 1,295,388 542,011 931.2 55 103 931.2 428.2 2017 900.7 892.7 8.0
DDKM17-126 Open Hole 1,295,696 542,639 906.8 55 103 906.8 327.7 2017 900.3 887.2 13.1
DDKM17-127 Open Hole 1,295,707 542,428 942.4 55 103 942.4 219.5 2017 909.0 882.6 26.4
DDKM17-127 Open Hole 1,295,707 542,428 942.4 55 103 942.4 219.5 2022 910.0 883.7 26.3
DDKM17-128 Open Hole 1,295,820 543,141 921.1 55 103 921.1 187.1 2017 892.5 871.1 21.4
DDKM17-130 Open Hole 1,295,476 542,215 943.2 55 103 943.2 360.1 2017 905.5 893.3 12.2
DDKM17-131 Stub Well 1,295,504 542,331 953.6 55 103 888.0 85.5 2017 915.9 887.9 28.0
DDKM17-131 Stub Well 1,295,504 542,331 953.6 55 103 888.0 85.5 2018 913.7 888.0 125.7
DDKM17-131 Stub Well 1,295,504 542,331 953.6 55 103 888.0 85.5 2021 916.8 888.5 28.3
DDKM17-131 Stub Well 11,295,504 1542,331 1953.6 155 1103 888.0 185.5 12022 1920.1 1888.8 131.3
Page 3 of 10

Groundwater Difference
Ground Measured Simulated
Eastingl Northing Bottom level l surface Dip Azimuth Top Screen groundwater groundwater between
Name Hole Type Screen measurement measured and
(ft) (ft) elevation (deg) (deg) (ft amsl) 2 level level
(ft amsl) (ft amsl) date m simulated
(year) (ft asl) (ft amsl) (ft)
DDKM17-131 Stub Well 1,295,504 542,331 953.6 55 1103 1888.0 85.5 2023 919.0 889.0 29.9
DDKM17-132 Open Hole 1,296,249 543,182 906.8 55 103 906.8 490.0 2017 862.1 833.6 28.5
DDKM17-133 Stub Well 1,295,754 542,341 946.2 55 103 896.9 367.1 2017 903.7 881.2 22.5
DDKM17-133 Stub Well 1,295,754 542,341 946.2 55 103 896.9 367.1 2018 903.5 881.3 22.2
DDKM17-133 Stub Well 1,295,754 542,341 946.2 55 103 896.9 367.1 2021 904.5 881.8 22.7
DDKM17-133 Stub Well 1,295,754 542,341 946.2 55 103 896.9 367.1 2022 903.6 882.1 21.5
DDKM17-133 Stub Well 1,295,754 542,341 946.2 55 103 896.9 367.1 2023 906.5 882.4 24.1
DDKM17-134 Open Hole 1,295,285 541,833 918.4 55 103 918.4 448.1 2017 894.4 891.9 2.5
DDKM17-135 Open Hole 1,295,920 543,230 905.0 55 103 905.0 613.4 2017 892.6 858.1 34.5
DDKM17-136 Open Hole 1,295,892 543,318 903.6 55 103 903.6 148.4 2017 891.9 855.8 36.1
DDKM17-137 Open Hole 1,294,871 541,813 923.0 55 103 923.0 385.5 2017 898.1 903.3 -5.2
DDKM17-138 Open Hole 1,295,541 542,599 920.4 55 103 920.4 256.6 2017 906.6 893.4 13.2
DDKM17-139 Open Hole 1,295,167 542,682 944.6 55 103 944.6 286.1 2017 916.9 908.6 8.3
DDKM17-139 Open Hole 1,295,167 542,682 944.6 55 103 944.6 286.1 2022 899.5 909.2 -9.8
DDKM17-140 Open Hole 1,296,360 543,528 800.6 90 0 800.6 -32.7 2017 798.9 783.4 15.5
DDKM18-141 Open Hole 1,296,390 544,125 798.7 50 103 798.7 304.8 2018 791.3 792.5 -1.2
DDKM18-142 Open Hole 1,296,386 544,126 798.7 70 103 798.7 27.9 2018 787.6 792.6 -5.0
DDKM18-143 Stub Well 1,296,377 543,752 801.8 80 103 751.8 187.9 2018 793.6 792.5 1.0
DDKM18-143 Stub Well 1,296,377 543,752 801.8 80 103 751.8 187.9 2018 792.9 792.5 0.4
DDKM18-144 Open Hole 1,296,384 543,750 801.6 55 103 801.6 444.2 2018 791.6 792.5 -0.9
DDKM18-145 Open Hole 1,295,712 542,354 946.6 55 103 946.6 449.4 2018 897.7 885.5 12.2
DDKM18-146 Open Hole 1,296,336 543,387 798.1 48 103 798.1 514.1 2018 794.1 dry n/a
DDKM18-148 Open Hole 1,296,017 543,356 882.9 90 103 882.9 623.7 2018 878.0 840.4 37.7
DDKM18-153 Open Hole 1,295,640 543,270 922.1 75 103 922.1 372.2 2018 906.3 878.8 27.5
DDKM18-155 Open Hole 1,295,652 543,269 921.6 55 103 921.6 676.8 2018 901.4 878.2 23.2
DDKM18-159 Open Hole 1,295,782 542,948 921.3 45 103 921.3 435.3 2018 904.9 880.2 24.7
DDKM18-162 Open Hole 1,295,404 542,494 947.1 70 103 947.1 460.0 2018 934.3 895.7 38.6
DDKM18-162 Open Hole 1,295,404 542,494 947.1 70 103 947.1 460.0 2022 905.2 896.6 8.7
DDKM18-173 Stub Well 1,296,249 542,956 929.2 75 103 870.0 422.1 2018 885.9 854.1 31.8
DDKM18-173 Stub Well 1,296,249 542,956 929.2 75 103 870.0 422.1 2021 879.3 857.4 21.9
DDKM18-173 Stub Well 1,296,249 542,956 929.2 75 103 870.0 422.1 2022 879.6 858.5 21.1
DDKM18-173 Stub Well 1,296,249 542,956 929.2 75 103 870.0 422.1 2023 877.3 859.8 17.5
DDKM18-178 Open Hole 1,296,121 542,789 906.3 75 103 906.3 405.6 2018 892.7 872.0 20.8
DDKM18-183 Open Hole 1,296,131 542,788 907.0 45 103 907.0 675.0 2018 894.5 871.7 22.8
DDKM18-190 Open Hole 1,295,750 542,775 911.7 55 103 911.7 617.4 2018 903.5 884.6 18.9
DDKM18-191 Open Hole 1,295,687 542,640 906.4 68 103 906.4 325.4 2018 906.6 887.7 18.8
DDKM18-195 Open Hole 1,295,746 542,777 911.8 75 103 911.8 322.4 2018 898.9 884.8 14.1
DDKM18-196 Open Hole 1,295,692 542,639 906.7 45 103 906.7 462.4 2018 906.1 887.6 18.6
DDKM18-200 Open Hole 1,295,194 542,052 942.7 55 103 942.7 284.3 2018 906.7 899.5 7.2
DDKM18-204 Open Hole 1,294,931 541,919 932.6 70 103 932.6 251.2 2018 902.9 903.5 -0.6
DDKM18-204 Open Hole 11,294,931 1541,919 932.6 70 103 932.6 251.2 2022 899.8 903.7 -3.8
DDKM18-205 Open Hole 1,294,941 541,916 932.4 55 103 932.4 394.9 2018 904.3 903.2 11.1
Page 4 of 10

Groundwater Difference
Ground Measured Simulated
Eastingl Northing Bottom level l surface Dip Azimuth Top Screen groundwater groundwater between
Name Hole Type Screen measurement measured and
(ft) (ft) elevation (deg) (deg) (ft amsl) 2 level level
(ft amsl) (ft amsl) date m simulated
(year) (ft asl) (ft amsl) (ft)
DDKM18-205 Open Hole 1,294,941 541,916 932.4 55 1103 1932.4 394.9 2022 903.4 903.4 0.0
DDKM18-207 Open Hole 1,295,914 542,753 904.1 55 103 904.1 318.2 2018 892.4 878.0 14.4
DDKM18-208 Open Hole 1,295,092 541,867 930.2 55 103 930.2 521.7 2018 907.2 898.1 9.1
DDKM18-210 Open Hole 1,294,919 541,697 917.5 55 103 917.5 387.5 2018 898.6 899.2 -0.6
DDKM18-213 Open Hole 1,294,857 541,611 921.3 55 103 921.3 359.6 2018 896.2 899.9 -3.8
DDKM18-214 Open Hole 1,295,583 542,992 922.4 55 103 922.4 46.2 2018 908.4 887.7 20.8
DDKM18-216 Open Hole 1,294,823 541,520 928.3 55 103 928.3 406.4 2018 892.2 899.3 -7.1
DDKM18-218 Open Hole 1,294,682 541,435 939.0 55 103 939.0 425.7 2018 895.5 900.7 -5.3
DDKM18-219 Open Hole 1,295,580 542,593 935.1 55 103 935.1 75.1 2018 915.6 886.4 29.2
DDKM18-221 Open Hole 1,294,588 541,257 943.0 55 103 943.0 308.7 2018 891.7 897.9 -6.2
DDKM18-224 Open Hole 1,297,216 545,355 841.0 55 97 841.0 182.6 2022 821.6 830.7 -9.0
DDKM18-225 Open Hole 1,294,896 541,396 925.4 55 103 925.4 428.2 2018 891.7 897.1 -5.4
DDKM18-228 Open Hole 1,297,129 545,369 841.0 70 97 841.0 85.7 2022 815.4 833.5 -18.0
DDKM18-230 Open Hole 1,295,454 541,777 901.4 55 103 901.4 444.6 2018 896.4 888.1 8.3
DDKM18-231 Open Hole 1,297,381 545,336 840.0 55 103 840.0 196.3 2022 815.1 829.7 -14.6
DDKM18-235 Open Hole 1,297,534 545,315 843.0 55 103 843.0 313.6 2022 814.3 827.3 -13.1
DDKM18-237 Open Hole 1,294,326 540,919 912.1 55 103 912.1 416.2 2018 884.9 886.1 -1.2
DDKM18-241 Stub Well 1,297,944 545,230 842.0 55 103 784.2 719.1 2018 794.9 810.9 -16.0
DDKM18-241 Stub Well 1,297,944 545,230 842.0 55 103 784.2 719.1 2021 810.3 825.7 -15.5
DDKM18-241 Stub Well 1,297,944 545,230 842.0 55 103 784.2 719.1 2022 812.8 828.8 -16.0
DDKM18-241 Stub Well 1,297,944 545,230 842.0 55 103 784.2 719.1 2023 810.9 832.5 -21.7
DDKM18-244 Open Hole 1,294,446 541,087 932.1 55 103 932.1 418.8 2018 889.3 893.2 -3.9
DDKM18-248 Open Hole 1,294,577 540,874 920.5 55 103 920.5 166.5 2018 874.6 885.0 -10.4
DDKM18-250 Open Hole 1,294,820 541,205 928.1 55 103 928.1 430.9 2018 884.7 893.6 -8.9
DDKM18-253 Open Hole 1,294,734 541,343 933.9 55 103 933.9 533.5 2018 905.9 899.7 6.2
DDKM18-255 Open Hole 1,294,960 541,288 920.0 55 103 920.0 592.1 2018 885.8 893.0 -7.2
DDKM18-258 Open Hole 1,294,995 541,169 913.5 55 103 913.5 617.8 2018 881.6 888.7 -7.1
DDKM18-282 Stub Well 1,296,602 545,152 901.0 70 200 834.9 -261.3 2018 858.3 834.0 24.3
DDKM18-282 Stub Well 1,296,602 545,152 901.0 70 200 834.9 -261.3 2021 859.0 845.0 14.1
DDKM18-282 Stub Well 1,296,602 545,152 901.0 70 200 834.9 -261.3 2022 859.7 847.8 11.9
DDKM18-282 Stub Well 1,296,602 545,152 901.0 70 200 834.9 -261.3 2023 859.2 850.7 8.5
DDKM18-291-127 VWP 1,297,892 545,261 883.1 70 225 763.42 763.42 2018 796.8 803.5 -6.7
DDKM18-291-127 VWP 1,297,892 545,261 883.1 70 225 763.42 763.42 2019 799.6 810.2 -10.7
DDKM18-291-127 VWP 1,297,892 545,261 883.1 170 225 763.42 763.42 2020 803.2 816.5 -13.3
DDKM18-291-297 VWP 1,297,850 545,225 883.1 70 225 603.10 603.10 2018 793.1 803.2 -10.1
DDKM18-291-297 VWP 1,297,850 545,225 883.1 70 225 603.10 603.10 2019 795.7 810.2 -14.5
DDKM18-291-297 VWP 1,297,850 545,225 883.1 70 225 603.10 603.10 2020 799.7 816.6 -16.9
DDKM18-291-604 VWP 1,297,773 545,162 883.1 70 225 320.30 320.30 2018 790.6 809.9 -19.3
DDKM18-291-604 VWP 1,297,773 545,162 883.1 70 225 320.30 320.30 2019 790.6 815.9 -25.3
DDKM18-291-604 VWP 1,297,773 545,162 1883.1 70 225 320.30 320.30 2020 793.9 1821.5 -27.6
DDKM18-291-897 VWP 1,297,698 545,103 883.1 70 225 37.47 37.47 2018 807.2 822.4 15.1
DDKM18-291-897 VWP 1,297,698 545,103 1883.1 170 1225 137.47 137.47 2019 802.7 1826.4 -23.7
Page 5 of 10

Groundwater Difference
Ground Measured Simulated
Eastingl Northing Bottom level l surface Dip Azimuth Top Screen groundwater groundwater between
Name Hole Type Screen measurement measured and
(ft) (ft) elevation (deg) (deg) (ft amsl) 2 level level
(ft amsl) (ft amsl) date m simulated
(year) (ft asl) (ft amsl) (ft)
DDKM18-291-897 VWP 1,297,698 545,103 883.1 70 1225 137.47 37.47 2020 806.2 830.6 -24.3
DDKM18-291-1197 VWP 1,297,620 545,048 883.1 70 225 -246.08 -246.08 2018 821.2 830.7 -9.5
DDKM18-291-1197 VWP 1,297,620 545,048 883.1 70 225 -246.08 -246.08 2019 817.2 833.6 -16.4
DDKM18-291-1197 VWP 1,297,620 545,048 883.1 70 225 -246.08 -246.08 2020 818.0 836.7 -18.7
DDKM18-298-131 VWP 1,296,540 544,969 937.5 70 20 805.63 805.63 2018 841.1 840.4 0.8
DDKM18-298-131 VWP 1,296,540 544,969 937.5 70 20 805.63 805.63 2019 847.8 841.6 6.2
DDKM18-298-131 VWP 1,296,540 544,969 937.5 70 20 805.63 805.63 2020 840.2 843.4 -3.2
DDKM18-298-131 VWP 1,296,540 544,969 937.5 70 20 805.63 805.63 2022 821.2 846.5 -25.3
DDKM18-298-351 VWP 1,296,571 545,037 937.5 70 20 609.23 609.23 2018 858.0 830.0 28.0
DDKM18-298-351 VWP 1,296,571 545,037 937.5 70 20 609.23 609.23 2019 853.9 834.2 19.7
DDKM18-298-351 VWP 1,296,571 545,037 937.5 70 20 609.23 609.23 2020 851.6 838.1 13.5
DDKM18-298-351 VWP 1,296,571 545,037 937.5 70 20 609.23 609.23 2022 841.3 843.8 -2.5
DDKM18-298-526 VWP 1,296,607 545,090 937.5 70 20 1446.74 446.74 2018 857.9 829.4 28.6
DDKM18-298-526 VWP 1,296,607 545,090 937.5 70 20 446.74 446.74 2019 854.9 834.0 20.9
DDKM18-298-526 VWP 1,296,607 545,090 937.5 70 20 446.74 446.74 2020 847.9 838.2 9.7
DDKM18-298-526 VWP 1,296,607 545,090 937.5 70 20 446.74 446.74 2022 837.0 844.4 -7.4
DDKM18-298-676 VWP 1,296,643 545,135 937.5 70 20 308.97 308.97 2018 863.6 828.2 35.4
DDKM18-298-676 VWP 1,296,643 545,135 937.5 70 20 308.97 308.97 2019 857.2 832.9 24.4
DDKM18-298-676 VWP 1,296,643 545,135 937.5 70 20 308.97 308.97 2020 856.0 837.2 18.8
DDKM18-298-676 VWP 1,296,643 545,135 937.5 70 20 308.97 308.97 2022 843.1 843.5 -0.4
DDKM18-298-1061 VWP 1,296,752 545,258 937.5 70 20 -37.08 -37.08 2018 850.5 839.6 10.9
DDKM18-298-1061 VWP 1,296,752 545,258 937.5 70 20 -37.08 -37.08 2019 809.4 843.0 -33.6
DDKM18-298-1061 VWP 1,296,752 545,258 937.5 70 20 -37.08 -37.08 2020 804.2 846.4 -42.2
DDKM18-298-1061 VWP 1,296,752 545,258 937.5 70 20 -37.08 -37.08 2022 798.4 851.6 -53.2
DDKM18-312-126 VWP 1,295,917 543,410 883.2 70 310 765.74 765.74 2018 884.3 848.5 35.8
DDKM18-312-126 VWP 1,295,917 543,410 883.2 70 310 765.74 765.74 2020 877.1 851.7 25.3
DDKM18-312-500 VWP 1,295,857 543,479 883.2 70 310 403.97 403.97 2018 915.7 852.9 62.8
DDKM18-312-500 VWP 1,295,857 543,479 883.2 70 310 403.97 403.97 2020 863.6 856.7 6.9
DDKM18-312-880 VWP 1,295,827 543,543 883.2 70 310 31.51 31.51 2018 946.5 858.2 88.3
DDKM18-312-880 VWP 1,295,827 543,543 1883.2 70 310 31.51 31.51 2020 873.9 861.5 12.3
DDKM18-312-1120 VWP 1,295,813 543,584 883.2 70 310 -204.22 -204.22 2018 966.4 861.0 105.4
DDKM18-312-1120 VWP 1,295,813 543,584 883.2 70 310 -204.22 -204.22 2020 849.5 863.7 -14.3
DDKM18-312-1285 VWP 1,295,810 543,609 883.2 70 310 -367.02 -367.02 2018 985.8 861.1 124.8
DDKM18-312-1285 VWP 1,295,810 543,609 883.2 70 310 367.02 367.02 2020 860.1 863.8 -3.7
DDKM18-340-129 VWP 1,295,037 541,416 914.2 80 180 799.99 799.99 2020 888.4 890.2 -1.9
DDKM18-340-129 VWP 1,295,037 541,416 914.2 80 180 799.99 799.99 2022 880.3 890.3 -10.0
DDKM18-340-384 VWP 1,295,038 541,327 914.2 80 180 561.50 561.50 2020 892.9 886.9 6.0
DDKM18-340-384 VWP 1,295,038 541,327 914.2 80 180 561.50 561.50 2022 883.4 887.0 -3.5
DDKM18-340-699 VWP 1,295,040 541,217 914.2 80 180 270.80 270.80 2020 883.1 879.8 3.3
DDKM18-340-699 VWP 1,295,040 541,217 914.2 80 180 270.80 270.80 2022 870.3 879.9 -9.6
DDKM18-340-980 VWP 1,295,042 541,119 914.2 180 180 10.66 110.66 12020 868.6 874.4 -5.9
DDKM18-340-980 VWP 1,295,042 1541,119 1914.2 180 1180 110.66 110.66 12022 860.2 1874.6 1-14.4
Page 6 of 10

Groundwater Difference
Ground Measured Simulated
Eastingl Northing Bottom level l surface Dip Azimuth Top Screen groundwater groundwater between
Name Hole Type Screen measurement measured and
(ft) (ft) elevation (deg) (deg) (ft amsl) 2 level level
(ft amsl) (ft amsl) date m simulated
(year) (ft asl) (ft amsl) (ft)
DDKM18-340-1158 VWP 1,295,044 541,055 914.2 80 1180 -156.94 -156.94 2020 860.2 871.7 -11.5
DDKM18-340-1158 VWP 1,295,044 541,055 914.2 80 180 -156.94 -156.94 2022 845.4 871.8 -26.4
KMMW-001 Historic Open 1,296,326 542,403 894.2 90 0 862.2 635.2 2018 866.2 864.1 2.1
KMMW-001 Historic Open 1,296,326 542,403 894.2 90 0 862.2 635.2 2021 862.8 864.8 -1.9
KMMW-001 Historic Open 1,296,326 542,403 894.2 90 0 862.2 635.2 2022 862.8 865.0 -2.2
KMMW-001 Historic Open 1,296,326 542,403 894.2 90 0 862.2 635.2 2023 860.8 865.3 -4.5
KMMW-002 Historic Open 1,295,288 542,702 932.3 90 0 862.3 632.3 2018 919.8 900.3 19.4
KMMW-002 Historic Open 1,295,288 542,702 932.3 90 0 862.3 632.3 2021 921.1 901.0 20.2
KMMW-002 Historic Open 1,295,288 542,702 932.3 90 0 862.3 632.3 2022 908.0 901.2 6.8
KMMW-002 Historic Open 1,295,288 542,702 932.3 90 0 862.3 632.3 2023 922.6 901.5 21.0
KMMW-003 Historic Open 1,295,286 542,713 932.9 90 0 870.9 703.9 2022 757.4 899.8 -142.4
KMMW-003 Historic Open 1,295,286 542,713 932.9 90 0 870.9 703.9 2023 922.4 900.1 22.3
KMMW-005 Historic Open 1,298,667 542,533 825.4 90 0 1775.4 568.4 2022 725.6 822.9 -97.3
RCKM17-011 Open Hole 1,297,010 543,527 818.0 55 103 818.0 633.7 2017 814.9 788.0 27.0
RCKM17-012 Stub Well 1,296,988 543,407 838.8 45 103 817.1 712.2 2017 829.4 822.8 6.6
RCKM17-012 Stub Well 1,296,988 543,407 838.8 45 103 817.1 712.2 2018 822.1 823.7 -1.6
RCKM17-012 Stub Well 1,296,988 543,407 838.8 45 103 817.1 712.2 2022 821.7 827.1 -5.4
RCKM17-033 Open Hole 1,295,638 542,927 922.0 55 103 922.0 558.3 2017 915.5 886.5 29.0
RTKM22-382 MW 1,295,480 541,278 913.8 90 0 753.8 1493.0 2022 872.3 877.6 -5.3
RTKM22-382 MW 1,295,480 541,278 913.8 90 0 753.8 493.0 2023 871.6 877.7 -6.1
RTKM22-387 MW 1,295,497 541,283 913.5 90 0 848.5 807.8 2022 873.0 879.3 -6.2
RTKM22-387 MW 1,295,497 541,283 913.5 90 0 848.5 807.8 2023 874.2 879.3 -5.2
RTKM22-392 MW 1,298,470 545,181 894.0 90 0 754.0 393.0 2022 845.5 833.4 12.1
RTKM22-392 MW 1,298,470 545,181 1894.0 90 0 754.0 393.0 2023 846.7 835.4 11.3
RTKM22-396 MW 1,298,475 545,172 893.8 90 0 853.8 743.8 2022 845.2 833.7 11.5
RTKM22-396 MW 1,298,475 545,172 893.8 90 0 853.8 743.8 2023 845.7 835.7 9.9
RTKM22-399 MW 1,296,505 544,848 942.3 90 0 912.3 832.3 2022 877.2 851.3 25.9
RTKM22-399 MW 1,296,505 544,848 942.3 90 0 912.3 832.3 2023 884.9 853.2 31.7
RTKM22-401 MW 1,296,451 544,459 972.4 90 0 942.4 822.4 2022 838.4 845.5 -7.0
RTKM22-401 MW 1,296,451 544,459 972.4 90 0 942.4 822.4 2023 868.1 847.0 21.0
RTKM22-403 MW 1,296,421 544,486 1972.2 90 0 937.2 817.2 2022 861.9 850.6 11.3
RTKM22-403 MW 1,296,421 544,486 972.2 90 0 937.2 817.2 2022 860.6 850.6 10.0
RTKM22-403 MW 1,296,421 544,486 972.2 90 0 937.2 817.2 2023 867.4 852.1 15.3
RTKM22-412 MW 1,296,094 545,406 962.3 90 0 927.3 762.3 2022 935.2 890.8 44.4
RTKM22-412 MW 1,296,094 545,406 962.3 90 0 927.3 762.3 2023 938.5 891.5 47.0
RTKM22-412 MW 1,296,094 545,406 962.3 90 0 927.3 762.3 2023 926.2 891.5 34.6
SNKM22-369 MW 1,294,480 540,325 936.9 90 0 936.9 794.4 2022 851.9 859.8 -7.9
SNKM22-373 MW 1,294,575 539,792 931.8 90 0 931.8 745.8 2022 866.8 854.7 12.1
SNKM22-374 MW 1,294,778 539,325 931.8 90 0 931.8 780.8 2022 832.8 841.9 -9.1
SNKM22-375 MW 11294,304 540,411 901.5 90 0 815.8 726.5 12022 1854.1 859.9 -5.8
SNKM22-375 MW 1,294,304 540,411 901.5 90 0 815.8 726.5 2022 1852.8 859.9 -7.1
SNKM22-375 MW 1,294,304 540,411 1901.5 90 0 815.8 1726.5 2023 1850.8 1859.9 -9.2
Page 7 of 10

Groundwater Difference
Ground Measured Simulated
Eastingl Northing Bottom level l surface Dip Azimuth Top Screen groundwater groundwater between
Name Hole Type Screen measurement measured and
(ft) (ft) elevation (deg) (deg) (ft amsl) 2 level level
(ft amsl) (ft amsl) date m simulated
(year) (ft asl) (ft amsl) (ft)
SNKM22-377 MW 1,295,355 539,542 929.1 90 10 1929.1 782.6 2022 831.9 833.9 -2.0
SNKM22-378 MW 1,295,761 540,081 932.2 90 0 932.2 761.2 2022 828.7 838.2 -9.5
SNKM22-380 MW 1,295,383 541,037 934.5 90 0 934.5 829.5 2022 863.4 877.3 -13.9
SNKM22-381 MW 1,296,358 540,533 893.6 90 0 893.6 772.6 2022 855.5 826.9 28.6
SNKM22-383 MW 1,297,645 541,165 862.4 90 0 862.4 676.4 2022 782.7 808.6 -25.9
SNKM22-384 MW 1,295,315 542,991 961.9 90 0 921.9 871.9 2022 921.0 905.8 15.2
SNKM22-384 MW 1,295,315 542,991 961.9 90 0 921.9 871.9 2022 921.2 905.8 15.4
SNKM22-384 MW 1,295,315 542,991 961.9 90 0 921.9 871.9 2022 918.4 905.8 12.6
SNKM22-384 MW 1,295,315 542,991 961.9 90 0 921.9 871.9 2023 923.1 906.1 17.0
SNKM22-385 MW 1,297,655 540,903 844.7 90 0 814.4 704.1 2022 792.9 806.2 -13.3
SNKM22-385 MW 1,297,655 540,903 844.7 90 0 814.4 704.1 2022 791.4 806.2 -14.8
SNKM22-385 MW 1,297,655 540,903 844.7 90 0 814.4 704.1 2022 787.9 806.2 -18.3
SNKM22-385 MW 1,297,655 540,903 844.7 90 0 814.4 704.1 2023 789.4 806.2 -16.8
SNKM22-386 MW 1,297,885 541,552 873.9 90 0 873.9 627.4 2022 823.7 815.2 8.5
SNKM22-388 MW 1,293,839 541,684 939.0 90 0 902.3 822.0 2022 892.2 900.4 -8.3
SNKM22-388 MW 1,293,839 541,684 939.0 90 0 902.3 822.0 2022 893.7 900.4 -6.8
SNKM22-389 MW 1,295,893 540,572 884.0 90 0 884.0 717.5 2022 870.9 865.0 6.0
SNKM22-391 MW 1,294,709 541,343 934.5 90 0 934.5 868.7 2022 898.3 900.0 -1.8
SNKM22-397 MW 1,294,341 538,165 883.7 90 0 883.7 727.7 2022 856.2 845.5 10.7
SNKM22-398 MW 1,294,863 538,692 828.6 90 0 803.9 733.6 2022 825.8 828.5 -2.6
SNKM22-398 MW 1,294,863 538,692 828.6 90 0 803.9 733.6 2022 824.7 828.5 -3.8
SNKM22-398 MW 1,294,863 538,692 828.6 90 0 803.9 733.6 2023 823.7 828.5 -4.8
SNKM22-400 MW 1,293,791 537,311 891.5 90 0 855.8 765.5 2022 831.3 840.4 -9.2
SNKM22-400 MW 1,293,791 537,311 891.5 90 0 855.8 765.5 2023 826.0 840.4 -14.4
SNKM22-402 MW 1,297,640 539,201 817.9 90 0 772.7 702.4 2022 776.5 786.9 -10.5
SNKM22-402 MW 1,297,640 539,201 817.9 90 0 772.7 702.4 2022 774.6 786.9 -12.4
SNKM22-402 MW 1,297,640 539,201 817.9 90 0 772.7 702.4 2023 777.1 786.9 -9.8
SNKM22-404 MW 1,295,982 539,190 877.4 90 0 877.4 732.4 2022 815.7 813.5 2.2
SNKM22-406 MW 1,292,465 540,839 952.4 90 0 927.7 847.4 2022 925.5 943.5 -18.0
SNKM22-406 MW 1,292,465 540,839 952.4 90 0 927.7 847.4 2023 924.8 943.5 -18.7
SNKM22-408 MW 1,293,264 540,028 965.9 90 0 965.9 890.9 2022 937.1 910.2 26.9
SNKM22-410 MW 1,298,530 539,598 831.3 90 0 831.3 704.8 2022 822.8 815.0 7.8
SNKM22-411 MW 1,297,899 539,784 916.1 90 0 916.1 821.1 2022 783.9 794.0 -10.1
SNKM22-413 MW 1,300,156 540,864 850.0 90 0 850.0 553.5 2022 824.5 834.5 -9.9
SNKM22-415 MW 1,298,671 538,894 845.3 90 0 845.3 679.8 2022 806.7 817.3 -10.6
SNKM22-416 MW 1,301,284 541,839 853.1 90 0 828.4 738.1 2022 851.8 853.9 -2.1
SNKM22-416 MW 1,301,284 541,839 853.1 90 0 828.4 738.1 2023 851.8 853.9 -2.1
SNKM22-417 MW 1,298,495 538,622 824.0 90 0 824.0 709.0 2022 807.2 811.7 -4.5
SNKM22-419 MW 1,299,174 539,896 840.3 90 0 840.3 705.3 2022 827.2 825.8 1.4
SNKM22-420 MW 1,298,040 537,558 843.7 90 0 818.5 778.2 2022 801.7 795.7 6.1
SNKM22-420 MW 11,298,040 537,558 1843.7 90 0 818.5 778.2 2023 800.4 795.7 4.7
SNKM22-421 MW 1,294,755 540,265 906.5 90 0 906.5 741.5 2022 859.2 865.7 -6.5
Page 8 of 10

Groundwater Difference
Ground Measured Simulated
Eastingl Northing Bottom level l surface Dip Azimuth Top Screen groundwater groundwater between
Name Hole Type Screen measurement measured and
(ft) (ft) elevation (deg) (deg) (ft amsl) 2 level level
(ft amsl) (ft amsl) date m simulated
(year) (ft asl) (ft amsl) (ft)
SNKM22-424 MW 1,299,960 542,770 907.0 90 10 1872.3 682.0 2022 872.0 866.1 5.9
SNKM22-424 MW 1,299,960 542,770 907.0 90 0 872.3 682.0 2023 870.7 866.1 4.6
SNKM22-426 MW 1,294,768 539,886 903.3 90 0 903.3 718.3 2022 845.1 859.3 -14.2
SNKM22-427 MW 1,294,964 539,479 906.4 90 0 906.4 781.4 2022 832.9 851.1 -18.3
SNKM22-428 MW 1,299,142 546,445 939.4 90 0 904.7 844.4 2022 901.7 869.0 32.7
SNKM22-428 MW 1,299,142 546,445 939.4 90 0 904.7 844.4 2023 897.8 869.1 28.7
SNKM22-430 MW 1,296,781 541,664 878.5 90 0 853.8 773.5 2022 852.0 843.4 8.6
SNKM22-430 MW 1,296,781 541,664 878.5 90 0 853.8 773.5 2023 851.5 843.5 8.0
SNKM22-432 MW 1,295,432 540,256 908.5 90 0 883.8 843.5 2023 851.2 867.4 -16.2
SNKM22-433 MW 1,301,184 537,463 861.3 90 0 836.6 756.3 2022 836.1 819.7 16.4
SNKM22-433 MW 1,301,184 537,463 861.3 90 0 836.6 756.3 2023 833.1 819.7 13.3
SNKM22-434 MW 1,296,207 540,807 863.5 90 0 788.8 758.5 2022 829.3 862.6 -33.3
SNKM22-434 MW 1,296,207 540,807 863.5 90 0 788.8 758.5 2023 831.3 862.6 -31.3
SNKM22-435 MW 1,301,014 539,213 829.2 90 0 804.5 774.2 2022 814.7 825.1 -10.4
SNKM22-436 MW 1,296,450 539,740 876.8 90 0 876.8 711.8 2022 812.7 804.4 8.3
SNKM22-437 MW 1,303,880 540,476 924.1 90 0 889.4 799.1 2022 882.4 878.0 4.4
SNKM22-437 MW 1,303,880 540,476 924.1 90 0 889.4 799.1 2023 877.9 878.0 -0.1
SNKM22-438 MW 1,295,961 544,004 943.2 90 0 913.5 793.2 2022 913.0 854.1 58.9
SNKM22-438 MW 1,295,961 544,004 943.2 90 0 913.5 793.2 2023 907.9 856.1 51.9
SNKM22-439 MW 1,297,075 543,097 922.0 90 0 867.3 837.0 2023 861.0 840.2 20.8
111_Joanne_Drive Private well 1,284,483 557,123 not surveyed -- -- -- -- 2023 777.6 774.0 3.6
113_Pearce_Dr Private well 1,291,167 543,525 not surveyed 2023 936.2 944.8 -8.6
116-1_Pearce_Dr Private well 1,291,292 543,900 not surveyed 2023 889.6 938.4 -48.8
125_Timms_Street Private well 1,292,568 542,232 not surveyed 2023 925.1 934.8 -9.7
127_Van_Dyke_Road Private well 1,293,922 524,531 not surveyed 2023 878.1 865.1 13.0
128-1_Chestnut_Ridge_Road Private well 1,302,968 560,503 not surveyed 2023 1,029.4 1,026.5 2.9
135_Hunters_Field_Way Private well 1,292,448 526,102 not surveyed 2023 795.0 821.2 -26.1
1417_S_Battleground_Avenue Private well 1,288,500 538,899 not surveyed 2023 944.8 920.1 24.7
142_Kristie_Lane Private well 1,296,003 563,221 not surveyed 2023 844.9 936.5 -91.7
171_Crystal_Brook_Drive Private well 1,280,852 539,000 not surveyed 2023 794.3 856.2 -61.9
208_Quarry_Road Private well 1,299,931 543,402 not surveyed 2023 862.3 855.5 6.9
302-1_Compact_School_Road Private well 1,290,085 536,789 not surveyed 2023 874.8 880.7 -5.9
462_Patterson_Road Private well 1,286,430 561,539 not surveyed 2023 833.1 849.7 -16.6
471_Alex_D_Owens_Road Private well 1,296,494 529,913 not surveyed 2023 862.9 892.4 -29.5
472_Alex_D_Owens_Road Private well 1,296,134 530,210 not surveyed 2023 881.7 886.1 -4.4
620_Margrace_Road Private well 1,289,127 541,411 not surveyed 2023 1,008.7 960.1 48.5
GS-289 Private well 1,325,440 585,190 938.0 2023 898.5 890.0 8.6
GS-290 Private well 1,325,440 585,190 938.0 2023 904.0 890.0 14.1
MW-07A Private well 1,297,462 553,216 936.0 749.0 739.0 2023 898.1 890.2 7.9
MW-12 Private well 1,297,247 552,800 904.7 834.7 824.7 2023 878.9 883.2 -4.3
MW-14 Private well 1,296,525 553,251 903.8 833.8 823.8 2023 850.4 868.8 -18.5
MW-15 Private well 11,296,813 1552,951 1904.1 814.1 784.1 2023 859.8 876.2 16.5
Page 9 of 10

Groundwater Difference
Ground Measured Simulated
Eastingl Northing Bottom level l surface Dip Azimuth Top Screen groundwater groundwater between
Name Hole Type Screen measurement measured and
(ft) (ft) elevation (deg) (deg) (ft amsl) 2 level level
(ft amsl) (ft amsl) date m simulated
(year) (ft asl) (ft amsl) (ft)
MW-16 Private well 1,297,094 552,967 906.5 1 1821.5 806.5 2023 876.8 881.0 -4.3
0.711-2 Private well 1,319,597 570,914 882.4 822.4 417.4 2023 853.4 854.2 -0.8
R73V3 Private well 1,269,584 526,295 879.5 -- -- 2023 875.8 797.1 78.7
RW-1 Private well 1,297,470 553,234 935.8 919.8 819.8 2023 891.2 890.5 0.7
RW-2 Private well 1,297,433 553,358 942.8 922.8 822.8 2023 854.9 890.3 -35.4
RW-3 Private well 1,297,617 553,346 942.1 922.1 822.1 2023 851.5 894.8 -43.4
1.This table uses The North American Datum of 1983(NAD 83)coordinate system,State Plane North Carolina FIPS 3,200 feet.
2.Groundwater level measurement date is year only because it is the average level from groundwater levels throughout the year.
Page 10 of 10

SRK Consulting(U.S.), Inc.
Hydrogeological Study and Groundwater Modeling—Kings Mountain Mining Project Appendices
Appendix C: Components of Pit Lake Balance
as Input for Pit Lake Chemistry Modeling
GEMS Ki ngsMou ntain_HydrogeoG W_Report_U SPR000576_Rev05.docx April 2024

Time since Time since Pit Lake
Pit Lake Direct Upcatchment Pit wall Spillover from Total Into Total Out Net In to Pit Lake
end of start of Pit Pit Lake Seepage(gpm) Evaporation Stage Precipitation runoff Runoff Pit Lake Pit Lake of Pit Lake Pit Lake Area Surface Volume
mining Lake
Year Year Groundwater Pit Lake to Net Out ft amsl m m m m m m m m acres acre-ft
to Pit Lake Groundwater gP gP gP gP gP gP gP gP
10.2 1 135.0 0.0 135.0 582.3 163.9 37.5 57.3 100.4 0.0 393.7 100.4 293.3 66.1 8,584.1
11.2 2 132.3 0.0 132.3 586.2 164.7 25.8 57.0 100.9 0.0 379.8 100.9 278.9 66.4 8,845.9
12 3 127.3 0.0 127.3 592.9 166.2 25.9 56.6 101.8 0.0 375.9 101.8 274.2 67.0 9,290.5
13 4 123.9 0.0 123.9 599.4 168.9 27.0 55.8 103.4 0.0 375.6 103.4 272.1 68.1 9,731.5
14 5 119.5 0.0 119.5 605.7 171.8 27.3 54.9 105.2 0.0 373.5 105.2 268.3 69.3 10,166.4
15 6 125.2 0.0 125.2 612.6 173.3 26.3 54.5 106.1 0.0 379.3 106.1 273.2 69.9 10,642.2
16 7 118.1 0.0 118.1 617.7 174.6 26.3 54.1 106.9 0.0 373.2 106.9 266.2 70.4 11,000.1
17 1 8 117.6 0.0 117.6 1 624.0 176.3 26.3 53.6 108.0 0.0 373.8 108.0 265.8 71.1 11,446.9
18 9 117.7 0.0 117.7 630.2 179.9 26.3 52.5 110.2 0.0 376.4 110.2 266.3 72.6 11,893.7
19 10 117.8 0.0 117.8 636.2 187.2 26.3 50.3 114.6 0.0 381.6 114.6 267.0 75.5 12,342.3
20 11 117.6 0.0 117.6 642.1 188.8 27.1 49.8 115.6 0.0 383.2 115.6 267.6 76.1 12,791.5
21 12 117.4 0.0 117.4 646.8 189.9 27.1 49.5 116.3 0.0 383.8 116.3 267.5 76.6 13,151.1
22 13 117.3 0.0 117.3 652.6 191.2 27.1 49.1 117.1 0.0 384.6 117.1 267.5 77.1 13,600.5
23 14 117.1 0.0 117.1 658.4 193.5 27.1 48.4 1 118.5 0.0 386.1 1 118.5 267.6 78.0 14,050.0
24 15 112.8 0.0 112.8 664.0 200.3 27.1 46.4 122.6 0.0 386.5 122.6 263.8 80.8 14,495.7
25 16 110.7 0.0 110.7 669.5 201.8 27.1 45.9 123.6 0.0 385.5 123.6 261.9 81.4 14,936.0
26 17 110.6 0.0 110.6 673.8 202.8 27.1 45.6 124.2 0.0 386.1 124.2 261.9 81.8 15,287.9
27 18 109.4 0.0 109.4 679.1 204.1 27.1 45.2 125.0 0.0 385.8 125.0 260.9 82.3 15,726.7
28 19 109.7 0.0 109.7 684.4 205.5 27.1 44.8 125.9 0.0 387.1 125.9 261.2 82.9 16,165.4
29 20 108.9 0.0 108.9 689.7 208.9 27.1 43.8 127.9 0.0 388.7 127.9 260.7 84.2 16,603.5
30 21 109.2 0.0 109.2 694.7 216.8 27.6 41.4 132.8 0.0 395.0 132.8 262.2 87.4 17,043.1
31 22 108.8 0.0 108.8 698.7 218.2 27.6 41.0 133.6 0.0 395.6 133.6 261.9 88.0 17,395.3
32 23 108.5 0.0 108.5 703.7 219.6 27.6 40.6 134.5 0.0 396.2 134.5 261.7 1 88.6 17,835.1
33 24 108.1 0.0 108.1 708.7 221.0 27.6 40.1 135.3 0.0 396.8 135.3 261.5 89.1 18,274.6
34 25 107.8 0.0 107.8 713.6 222.6 27.6 39.7 136.3 0.0 397.6 136.3 261.3 89.8 18,713.7
35 26 107.5 0.0 107.5 718.4 224.7 27.7 39.0 137.6 0.0 399.0 137.6 261.3 90.6 19,152.7
36 27 106.7 0.0 106.7 722.3 228.3 27.7 37.9 139.8 0.0 1 400.7 139.8 260.9 92.1 19,503.6
37 28 106.0 0.0 106.0 727.0 230.4 27.7 37.3 141.1 0.0 401.4 141.1 260.3 92.9 19,941.1
38 29 105.6 0.0 105.6 731.7 231.9 27.7 36.9 142.0 0.0 402.1 142.0 260.1 93.5 20,378.2
39 30 105.2 0.0 105.2 736.3 233.4 27.7 36.4 143.0 0.0 402.8 143.0 259.8 94.1 20,814.8
40 31 104.6 0.0 104.6 740.9 235.0 27.1 36.0 143.9 0.0 402.6 143.9 258.7 94.8 21,250.1
41 32 103.0 0.0 103.0 744.6 236.4 27.1 35.5 144.8 0.0 402.1 144.8 257.3 95.3 21,596.3
42 33 101.8 0.0 101.8 749.0 239.3 27.1 34.7 146.5 0.0 402.8 146.5 256.3 96.5 22,027.3
43 34 101.1 0.0 101.1 753.4 247.8 27.1 32.1 151.7 0.0 1 408.1 151.7 256.3 99.9 22,458.0
44 35 99.9 0.0 99.9 757.6 250.6 27.1 31.3 153.4 0.0 408.9 153.4 255.4 101.0 22,887.7
45 36 97.7 0.0 97.7 761.9 252.1 27.8 30.8 154.4 0.0 408.4 154.4 254.0 101.7 23,315.5
46 37 96.6 0.0 96.6 765.2 253.2 27.8 30.5 155.0 0.0 408.0 155.0 252.9 102.1 23,655.8
47 38 94.3 0.0 94.3 769.3 254.4 27.8 30.1 155.8 0.0 406.6 155.8 250.8 102.6 24,078.0
48 39 92.4 0.0 92.4 1 773.4 255.7 27.8 29.7 156.6 0.0 405.6 156.6 249.0 103.1 24,497.4
49 40 90.0 0.0 90.0 777.4 257.3 27.8 29.3 157.6 0.0 404.3 157.6 246.7 103.7 24,913.2
50 41 88.3 0.0 88.3 781.4 260.7 28.3 28.3 159.6 0.0 405.5 159.6 245.9 105.1 25,326.5
51 42 85.2 0.0 85.2 784.5 262.6 28.3 27.7 160.8 0.0 403.8 160.8 243.0 105.9 25,654.0
52 43 82.7 0.0 82.7 788.3 264.2 28.3 27.2 161.8 0.0 402.4 161.8 240.6 106.5 26,059.3
53 44 80.1 0.0 80.1 792.1 265.7 28.3 26.8 162.7 0.0 400.8 162.7 238.1 107.1 26,460.8
54 45 77.4 0.0 1 77.4 795.7 267.0 1 28.3 26.4 163.5 0.0 399.1 163.5 235.6 107.6 26,857.8
55 46 74.4 0.0 74.4 799.4 268.2 28.6 26.0 164.2 1 0.0 397.1 164.2 232.9 108.1 27,250.6
56 47 71.8 0.0 71.8 802.3 269.2 28.6 25.7 164.9 0.0 395.3 164.9 230.4 108.6 27,561.1
57 48 68.5 0.0 68.5 805.8 270.6 28.6 25.3 165.7 0.0 393.0 165.7 227.3 109.1 27,944.4
58 49 64.9 0.0 64.9 809.2 275.3 28.6 23.8 168.6 0.0 392.6 168.6 224.0 111.0 28,322.9
59 50 1 62.0 0.0 62.0 812.5 280.3 28.6 22.4 171.6 0.0 393.2 171.6 221.5 113.0 28,696.2
Page 1 of 2

Time since Time since Pit Lake
Pit Lake Direct Upcatchment Pit wall Spillover from Total Into Total Out Net In to Pit Lake
end of start of Pit Pit Lake Seepage(gpm) Evaporation Stage Precipitation runoff Runoff Pit Lake Pit Lake of Pit Lake Pit Lake Area Surface Volume
mining Lake
Year Year Groundwater Pit Lake to Net Out ft amsl m m m m m m m m acres acre-ft
to Pit Lake Groundwater gP gP gP gP gP gP gP gP
60 51 60.0 0.0 60.0 815.8 282.1 28.9 21.8 172.7 0.0 392.7 172.7 220.0 113.7 29,066.4
61 52 57.1 0.0 57.1 818.4 283.1 28.9 21.5 173.3 0.0 390.6 173.3 217.3 114.1 29,359.1
62 53 52.9 0.0 52.9 821.5 284.3 28.9 21.2 174.1 0.0 387.3 174.1 213.1 114.6 29,719.4
63 54 49.0 0.7 48.3 824.6 285.6 28.9 20.8 174.9 0.0 384.3 175.7 208.6 115.2 30,071.8
64 55 46.5 2.4 44.1 827.6 287.5 28.9 20.2 176.1 0.0 383.1 178.5 204.6 115.9 30,418.3
65 56 44.6 3.2 41.4 830.5 289.6 27.2 19.6 177.3 0.0 381.0 180.5 200.4 116.8 30,757.1
66 57 42.8 6.4 36.5 832.7 291.0 27.2 19.1 178.2 0.0 380.2 184.6 195.6 117.3 31,021.9
67 1 58 41.1 8.4 32.6 1 835.5 292.8 27.2 18.6 179.3 0.0 1 379.7 187.8 192.0 118.1 31,346.2
68 59 39.3 11.8 27.5 838.2 294.8 27.2 18.0 180.5 0.0 379.3 192.3 187.0 118.9 31,662.9
69 60 37.9 15.2 22.7 840.7 298.1 27.2 17.0 182.5 0.0 380.3 197.7 182.5 120.2 31,971.6
70 61 36.6 19.6 16.9 843.2 301.2 26.8 16.1 184.4 0.0 380.6 204.1 176.5 121.4 32,272.4
71 62 36.0 21.5 14.4 845.2 302.8 26.8 15.6 185.4 0.0 381.1 207.0 174.2 122.1 32,506.9
72 63 34.2 28.7 5.5 847.4 304.8 26.8 15.0 186.7 0.0 380.8 215.3 165.4 122.9 32,788.1
73 64 33.1 34.1 -1.0 849.7 306.5 26.8 14.5 187.7 0.0 380.9 221.8 159.1 123.6 33,059.4
74 65 35.0 27.2 7.8 850.1 307.0 26.8 14.3 188.0 163.9 383.2 379.2 4.0 123.8 33,120.1
75 66 37.1 24.1 13.0 850.1 307.0 26.8 14.3 188.0 173.0 385.2 385.1 0.1 123.8 33,120.2
76 67 37.7 1 23.8 14.0 850.1 307.0 26.8 14.3 188.0 174.1 385.9 385.9 0.0 123.8 33,120.3
77 68 38.2 23.6 14.6 850.1 307.0 26.8 14.3 188.0 174.7 386.4 386.4 0.0 123.8 33,120.3
78 69 38.2 23.6 14.6 850.1 307.0 26.8 14.3 188.0 174.7 386.4 386.4 0.0 123.8 33,120.3
79 70 38.2 23.6 1 14.6 850.1 1 307.0 1 26.8 14.3 188.0 174.7 386.4 386.4 0.0 123.8 33,120.3
80 71 38.2 23.6 14.6 850.1 307.0 26.8 14.3 188.0 174.7 386.4 386.4 0.0 123.8 33,120.3
Water balance in pit lake does not change after 77 years since start of mining
Page 2 of 2