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Home My WebLink AboutNCG021045_Operational Erosion Sedimentation Plan_20240815 Archdale Development and Operational Erosion and Sediment Control Plan Kings Mountain Mining Project Report Date: April 4, 2024 Report Prepared for A 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-9052 North Carolina Firm License Number: C-5030 Author: Mauricio Herrera, PhD, P.Eng., Principal Consultant Reviewed by: David Hoekstra, BS, PE, NCEES, SME-RM, Principal Consultant SRK Consulting(U.S.), Inc. Erosion and Sediment Control Plan Template—Kings Mountain Page ii Executive Summary SRK Consulting (U.S.), Inc. (SRK) has developed an erosion and sediment control plan (ECP)for the Archdale tailings storage facility (TSF) component of the Kings Mountain Mining Project (the Project) has been developed in support of the prefeasibility study (PFS) environmental assessment (EA) application. The ECP was prepared for the proposed life-of-mine (LoM), including construction, operation, and concurrent reclamation. A separate ECP will be prepared to address the closure, decommissioning, and reclamation of the facility. Design criteria have been selected based on applicable regulations and associated guidance documents, including the North Carolina Surface Mining Manual (1996), the Global Industry Standard on Tailings Management (GISTM) (2020) Flood Design Criteria, and with consideration for Project-specific risks. The objective of the ECP is to provide a strategy for specific Project locations that require controls to reduce the amount of erosion and sedimentation that can occur because of the Project. Design criteria for the Project have been selected to meet or exceed the requirements of the North Carolina Surface Mining Manual (1996) and the North Carolina Erosion and Sediment Control Planning and Design Manual (NCSCC) (2013). Table 1 shows the selected criteria and the North Carolina recommendations. Table 1: Surface Water Design Criteria Infrastructure Project Design Criteria Recommended by North Carolina Type Mining Manual 1996 and NCSCC Permanent channels Probable maximum precipitation 10-year storm (temporary) adjacent to the TSF PMP local storm 25-year storm permanent Permanent channels in 100-year storm 10-year storm (temporary) the non-process area 25- ear storm (permanent) Culverts PMP local storm 25-year storm 25-year storm for all sediment control ponds 0 10-year storm (less than (<)20 acres(ac)) Ponds 100 percent(/o)containment of 25-year storm (greater than (>)20 ac) the PMP storm event for TSF collection pond Permanent Probable maximum flood (PMF) 10-year storm (temporary) channels 25-year storm (permanent) Culverts PMF 25-year storm Ponds 25-year storm for all ponds 10- ear storm <20 ac 25- ear storm >20 ac Non-contact perimeter channels are designed to route runoff from undisturbed areas around Project infrastructure into Archdale Creek, maintaining clean water. Erosion protection for channels was selected based on the maximum tributary catchment throughout the life of the Project and the expected velocities during design flood events. Most of the channels are grass-lined, while those segments with steeper gradient are lined with riprap. One sediment control pond will be situated downstream of the TSF perimeter channels to manage non-contact water from the active TSF perimeter corridor before discharging into Archdale Creek. Non- contact water collected from areas in the non-process infrastructure components of the Archdale site will be revegetated or resurfaced during the initial development stage and will only require sediment controls during the facility construction. Once the surfaces have stabilized, non-contact water from these areas will be conveyed through the Project site and released to Archdale Creek without additional sediment requirement. MH/DH April 2024 SRK Consulting(U.S.), Inc. Erosion and Sediment Control Plan Template—Kings Mountain Page iii Table of Contents ExecutiveSummary.......................................................................................................... ii 1 Project Description...................................................................................................... 1 1.1 Site Description...................................................................................................................................1 1.2 Property Location................................................................................................................................3 1.3 Property History ..................................................................................................................................3 1.4 Project Overview.................................................................................................................................4 1.4.1 Project Layout .........................................................................................................................4 2 Erosion and Sediment Controls ................................................................................. 6 2.1 Design Objectives...............................................................................................................................6 2.2 Design Criteria ....................................................................................................................................6 2.2.1 North Carolina Surface Mining Manual (1996)........................................................................6 2.2.2 Project-Adopted Criteria..........................................................................................................7 2.3 Methodology........................................................................................................................................7 3 Erosion and Sediment Controls ................................................................................. 8 4 Construction Schedule.............................................................................................. 10 4.1 Phase 1: Site Preparation.................................................................................................................10 4.1.1 Topsoil Salvage and Unsuitable Soil Removal .....................................................................10 4.2 Phase 2: Facility Construction ..........................................................................................................10 4.2.1 Perimeter Access Road and Starter Embankment Construction..........................................10 4.2.2 TSF Interior Base and Side Slope Design ............................................................................11 4.3 Phase 3: Operations .........................................................................................................................11 4.3.1 Raise Construction................................................................................................................11 4.3.2 Tailings Placement and Tailings Surface Management........................................................11 4.3.3 Stormwater Management......................................................................................................12 4.4 Phase 4: Closure...............................................................................................................................12 5 Planned Erosion and Sedimentation Control Practices ......................................... 13 5.1 Permanent Development- and Operational-Stage Practices............................................................13 5.1.1 Permanent Sediment Control Pond ......................................................................................13 5.1.2 Sediment Fence (Practice 6.62)............................................................................................14 5.1.3 Permanent Grass-Lined Channels (Practice 6.21 and Practice 6.30)..................................14 5.1.4 Permanent Riprap-Lined Channels (Practice 6.21 and Practice 6.31).................................15 5.1.5 Permanent Outlet Protection Level Spreader (Practice 6.40)...............................................15 5.1.6 Operational Dust Control (Practice 6.84)..............................................................................15 5.1.7 Operational Temporary Seeding (Practice 6.10) ..................................................................15 5.2 Closure Stage Practices ...................................................................................................................15 MH/DH April 2024 SRK Consulting(U.S.), Inc. Erosion and Sediment Control Plan Template—Kings Mountain Page iv 5.3 Temporary Development Stage Practices........................................................................................15 5.3.1 Temporary Dust Control (Practice 6.84) ...............................................................................16 5.3.2 Temporary Sediment Traps (Practice 6.60)..........................................................................16 5.3.3 Sediment Fence (Practice 6.62)............................................................................................16 6 Maintenance Plan....................................................................................................... 17 7 Detail Drawings and Specifications for Practices Specified.................................. 19 8 Vegetation Plan.......................................................................................................... 24 9 Supporting Calculations............................................................................................ 25 10 Financial Responsibility/Ownership Form............................................................... 26 11 Checklist..................................................................................................................... 27 12 References.................................................................................................................. 28 Disclaimer........................................................................................................................ 29 Copyright ......................................................................................................................... 29 List of Tables Table 1: Surface Water Design Criteria.............................................................................................................. ii Table 2.1: Project Design Criteria for Surface Water Infrastructure...................................................................7 Table 5.1: TSF Sediment Pond Volume and Surface Areas............................................................................14 Table 8.1: Preliminary Seed Mix Composition and Schedule ..........................................................................24 List of Figures Figure1.1: Location Map....................................................................................................................................2 Figure 1.2: Preliminary Kings Mountain Mining Project Archdale Site Map.......................................................4 Figure 3.1: Archdale Erosion and Sediment Control Plan..................................................................................9 Figure 7.1: Skimmer and Riser Sediment Basin with Permanent Wet Pond ...................................................19 Figure7.2: Rock Check Dam............................................................................................................................20 Figure 7.3: Typical Riprap Channel Cross-Section ..........................................................................................21 Figure 7.4: Outlet Stabilization Structure..........................................................................................................22 Figure 7.5: Typical Operational Paved Flume..................................................................................................23 MH/DH April 2024 SRK Consulting(U.S.), Inc. Erosion and Sediment Control Plan Template—Kings Mountain Page v List of Abbreviations The US System for weights and units has been used throughout this report. Tons are reported in short tons of 2,000 lbs. All currency is in U.S. dollars (US$) unless otherwise stated. Abbreviation Unit or Term percent < less than > greater than ac acre Albemarle Albemarle Corporation amsl above mean sea level cfs cubic feet per second CWP contact water pond EA environmental assessment ECP erosion and sediment control plan ESRI Environmental Systems Research Institute, Inc. Foote Foote Mineral Company ft foot ft2 s uare foot ft3 cubic foot GISTM Global Industry Standard on Tailings Management pm gallons per minute 1-85 Interstate 85 LoM life-of-mine MSHA Mine Safety and Health Administration NCSCC North Carolina Erosion and Sediment Control Planning and Design Manual NPI non-process infrastructure PFS prefeasibility stud PMF probable maximum flood PMP probable maximum precipitation Project Kings Mountain Mining Project SRK SRK Consulting (U.S.), Inc. SWCA SWCA Environmental Consultants TSF I tailings storage facility MH/DH April 2024 SRK Consulting(U.S.), Inc. Erosion and Sediment Control Plan Template—Kings Mountain Page 1 1 Project Description The Project is a legacy open pit lithium mining operation located in the city of Kings Mountain, North Carolina, in the southeastern United States. The Project is a lithium pegmatite deposit that is currently being investigated for redevelopment by Albemarle Corporation (Albemarle)as part of a prefeasibility- level analysis. Albemarle commissioned SRK to develop prefeasibility-level (evaluate and select phases, per Albemarle's internal conventions)designs for an expansion of the existing pit, waste rock management, water management, and ancillary infrastructure to aid Albemarle in making informed decisions concerning advancement of the Project. As part of this study, SRK is developing a PFS surface water design of stormwater management controls to divert clean, non-contact water around the facilities.At the same time,the design intercepts waters that have come into contact with mining activities and routes them to monitoring or treatment facilities prior to discharge into the existing natural drainage system. This document provides a detailed ECP for the Archdale TSF. 1.1 Site Description Situated in Cleveland County, the mine is approximately 35 miles west of Charlotte, North Carolina. Located amidst rolling hills of the Piedmont Plateau, the Project is in a predominantly rural setting within the city of Kings Mountain. The mine site covers a significant land area, which includes both the proposed extraction areas and associated processing infrastructure. Figure 1.1 shows the location of the Archdale TSF. MH/DH April 2024 SRK Consulting(U.S.), Inc. Erosion and Sediment Control Plan Template—Kings Mountain Page 2 Galax 1 11 91ue Ridge P:ikway 1 � r25I Statesville Asheville 5au[h Ma4■esuille Mounui ns Gi81,e Land LaU North Cafdlina ri sa Green River —` Shelby !;a-io I.nnr1 [ia5[d11id 4 Charlotte Iryr Spartanburg Wadewampmn �RgCkHIM ❑ GreerMlle yet South Carolina Mies Source: Environmental Systems Research Institute, Inc. (ESRI),2023(modified by SRK) Figure 1.1: Location Map As part of this study, SRK is developing a PFS surface water design of stormwater management channels, detention and retention ponds, sediment control structures, and spillways that meet the required design criteria for each facility, which were selected using a risk-based approach. MH/DH April 2024 SRK Consulting(U.S.), Inc. Erosion and Sediment Control Plan Template—Kings Mountain Page 3 Incorporated within the surface water design for the Project, SRK developed the ECP for the development and operational stage of the Project. These phases cover the period from the initial site development to the end of mining and start of the closure and reclamation of the Project site. The ECP was developed according to the NCSCC(2013), isolating non-contact runoff from the contact water produced during mining and detailing the non-contact runoff in one of three sediment control structures. 1.2 Property Location Situated in Cleveland County, the mine is approximately 35 miles west of Charlotte, North Carolina. Located amidst rolling hills of the Piedmont Plateau, the Project is in a predominantly rural setting within the city of Kings Mountain. The mine site covers a significant land area, which includes both the proposed extraction areas and associated processing infrastructure. Figure 1.1 shows the location of the mine and the location of the Archdale TSF. 1.3 Property History The following summary highlights the history of the site, compiled from records available to SRK: • Mining started in 1883 with the discovery of cassiterite, a tin-bearing mineral, within the outcropping pegmatites. • Subsequently, open pit mining for tin occurred sporadically between 1903 and 1937 (Horton and Butler, 1988). • Between 1943 and 1945, under the sponsorship of the U.S. government, Solvay established a processing plant and mined for spodumene from the outcropping pegmatites(Garrett,2004). • In the early 1950s, Foote Mineral Company (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 operations ceased when the open pit bottom reached approximately 660 feet(ft) above mean sea level (amsl). • In early 1994, an open pit lake started to form due to rebounding groundwater, and the pit lake reached an elevation of 818.67 ft amsl (as of November 2023). • During the groundwater recovery period (1994 to present), water was sporadically pumped from the Kings Mountain pit lake to a nearby quarry (Martin Marietta) to support quarry operation. • Albemarle acquired the site in 2015, resuming exploration and mine development activities. The proposed Archdale TSF will be located at the site of a former mica mine. The following summary of the site is compiled from records available to SRK: • The site was formerly owned by the Kings Mountain Mica Company, which began operation in 1949. • The site was owned by several different companies between 1994 and 2021, including Franklin Minerals, Oglebay Norton, Zemex, General Chemical, and Imerys. • Imerys expanded mining to the property north of the Archdale site across Highway 29 in 2011. • Albemarle acquired the site in 2023 for use as a permanent storage of filtered tailings from the Project. MH/DH April 2024 SRK Consulting(U.S.), Inc. Erosion and Sediment Control Plan Template—Kings Mountain Page 4 Available aerial photography of the site suggests that mining activities continued through about 2013. The current site layout encompasses several shallow in-pit ponds formed during the previous mica mining operations. Figure 1.2 shows a detailed map of the current site layout. GFTE ENTRANCE -- - -- FEET IMFT.PERIMETER HIGH POINT HAULI ACCESS ROAD l FILTERED % TAILING_ STOR..GE LIGHT VEH[CLE ENTRANCE / / CRE`L FILL T 960 ElFAN nss1 SEEPAGE INTERCEPTI DRAIN PERIMETER ACCESS ROA➢ WATERAN❑SEWER MAIN �1 LIGHTVEHICLE ACCESS ROAD EXISTING CULVERTS(TYP.) PROPOSED CUL`,'ERT;TYP / SEDIMENT BASINS FUEL PAD MAINTENANCE SHOP �(�,� / SEEPAGE COLLECTION TANK CULVERT ABLE TO PASS PUP PROPERTY BOUNDARYOVERHE4D POW ER TON ACT WATER POND GROWN-I MEDIA STOCKPILE(-200k LAY DOWN AREA / TRIJ-PARKING PARKING Source:SRK 2023 Figure 1.2: Preliminary Kings Mountain Mining Project Archdale Site Map 1.4 Project Overview Tailings from the spodumene concentrate process at the Project will be filtered to approximately 10% to 15% moisture content by weight and transported off-site to the proposed Archdale TSF for disposal. A portion of the waste rock mined at the Project will be transported to Archdale for construction of the TSF embankment. An initial TSF embankment will be constructed on-site to hold approximately 1 to 2 years of filtered tailings. Thereafter, filtered tailings material will be placed and compacted with mobile equipment at the same time the TSF perimeter embankment is raised with compacted waste rock and/or fill. The TSF will be constructed in this manner until the facility reaches its capacity, at which time the facility will be closed and reclaimed. 1.4.1 Project Layout Figure 1.2 shows the Project layout and the relative locations of the major components of the Project. The Project is bounded by Interstate 85 (1-85) on the south and Highway 29 on the north. Access to the TSF will be from Highway 29 with separate truck and light vehicle entrances. The proposed MH/DH April 2024 SRK Consulting(U.S.), Inc. Erosion and Sediment Control Plan Template—Kings Mountain Page 5 Archdale site will include a small office and maintenance facilities, parking,water storage and sediment control facilities as part of the non-process infrastructure (NPI), and a TSF perimeter access road. Spaces for a small road base stockpile and a growth media storage area are included in the site plan. MH/DH April 2024 SRK Consulting(U.S.), Inc. Erosion and Sediment Control Plan Template—Kings Mountain Page 6 2 Erosion and Sediment Controls 2.1 Design Objectives The objective of the ECP is to provide a strategy for specific Project locations that require controls to reduce the amount of erosion and sedimentation that can occur because of the Project. 2.2 Design Criteria The following standards and guidelines apply with respect to surface water controls: • Surface Mining Manual. A Guide for Permitting, Operation, and Reclamation. State of North Carolina Department of Environment, Health, and Natural Resources. Division of Land Resources. Land Quality Section. February 1996. • Erosion and Sediment Control Planning and Design Manual. North Carolina. May 2013. North Carolina Sedimentation Control Commission, North Carolina Department of Environment and Natural Reserves, and the North Carolina Agricultural Extension Services. • GISTM 2020 Flood Design Criteria. 2.2.1 North Carolina Surface Mining Manual (1996) The North Carolina Surface Mining Manual (1996) stipulates that: • Temporary diversions(those that function for<1 year)should be designed to carry at least the 10-year design storm for the total drainage area; furthermore: o Temporary diversions require erosion protection. Velocities over 2.5 ft per second may require a temporary liner with supporting design calculations unless the soil is especially erosion resistant. o Side slopes of the diversion berm should be constructed to a 2 horizontal to 1 vertical or flatter. The slopes should then be immediately seeded. o Permanent ditches and channels (those constructed to function for more than 1 year and to carry concentrated runoff non-erosively to a predetermined destination) must be designed for the 25-year storm event for the total drainage area; furthermore: o Side slopes must be 2 horizontal to 1 vertical or flatter. o Grass-lined channels are generally used for slopes <5%. o Velocities should not exceed 5 ft per second for established grass-lined channels. o Sharp bends and turns should be avoided. o Velocities over the maximum allowable design velocity for grass-lined channels require a permanent structural lining, such as riprap. o In cases where velocity allows, riprap may be installed in the bottom of the channel with grass-lined side slopes to decrease the quantity of riprap needed. Filter fabric or a 6-inch deep sand gravel crushed stone filter must be installed under the riprap to prevent undermining. The filter should extend under the entire area of the riprap lining. o The receiving channel or outlet must be protected from erosion by ensuring that the outlet velocity is minimized. o Outlet protection should be included if necessary. MH/DH April 2024 SRK Consulting(U.S.), Inc. Erosion and Sediment Control Plan Template—Kings Mountain Page 7 o Channels must be stabilized as soon as possible after construction, and sediment-laden runoff must be diverted away from stabilized channels. o Channels must be inspected after every major rainfall and appropriately repaired. 2.2.2 Project-Adopted Criteria Table 2.1 shows project-adopted criteria for the surface water infrastructure (channels, culverts, and sediment ponds)that generally exceeded the North Carolina Mining Manual's recommendations. Table 2.1: Project Design Criteria for Surface Water Infrastructure Infrastructure Project Design Criteria Recommended by North Carolina Type Mining Manual 1996 and NCSCC Permanent channels PMP local storm 10-year storm (temporary) adjacent to the TSF 25- ear storm (permanent) Permanent channels in 100-year storm 10-year storm (temporary) the non-process area 25- ear storm (permanent) Culverts PMP local storm 25-year storm 25-year storm for all sediment control ponds Ponds 100%containment of the PMP storm event 10-year storm ( 20 ac) for TSF collection and 25-year storm (>20 ac) Source:SRK,2023 2.3 Methodology SRK incorporated a stormwater management approach of using runoff treatment; all disturbed areas are managed by sediment control measures, consisting of sediment mitigation at the source and wet ponds or stormwater wetlands to manage discharges to the existing drainages. SRK conducted hydrologic and hydraulic modeling for sizing the channels, determining the erosion protection required, and for sizing the sediment control pond. A description of the methodology is presented in the main report to which this document is an appendix (Archdale Surface Management Report(SRK, 2024)). Appendix B of the main report includes a summary of the calculations. MH/DH April 2024 SRK Consulting(U.S.), Inc. Erosion and Sediment Control Plan Template—Kings Mountain Page 8 3 Erosion and Sediment Controls The Preliminary Archdale Tailings Storage Facility Design Drawing Package (SRK, 2024a) presents the TSF's detailed perimeter sections, profiles, and plans. Figure 3.1 shows the channel layout that will be constructed to provide surface water management control during operations, as well as the sediment and erosion controls, including the following: • Sediment pond control with skimmer • Culvert outlet stabilization • Permanent grass-lined channels • Permanent riprap-lined channels • Temporary silt fences • Level spreaders • Rock check dams The channels were sized to safely convey the peak flow produced by the design storm event using the maximum catchments that will contribute to them during the operational period. Channels will be reconfigured during the closure period to address post-closure flows, as described in the separately provided closure plan report (SRK, 2024b). MH/DH April 2024 SRK Consulting(U.S.), Inc. Erosion and Sediment Control Plan Template—Kings Mountain Page 9 UGHT4F}11CLE AND HAUL 1 .In..�..».r __-__ LEGEND • �� VEHICLE SEPARATION BERM � � - _ - wx,ttnxs I�usnYCl •rl '^' 'r' Iw T.FERIMET HAUL/ACCESS ROAk - wnxntinuTsvccl¢p r 'IF LIGHT VEHICLE ACCESS WATER A146SEWER MAIN ---_ '`_ ROCK CHECK DAM SIT€ENTRANCE .uir>F wxTCE �F RFVEGETATFI} y -, L C,CVYSTRI K:TION OUT SLOPE _ _ _ ane�nerr.nc� - - - rxu t _� +� —_ly f GRAVEL T '" x rvncnux� 1` ] i,I Ii� ti.4'ti ',I =4114 TRAFFIC SURFACE , u•c�•_ k t 'r�y �.f F. Ir �'f- i C� pA 111f.!PM FdPMfi PERLMAHENT SELV EH'r { .v PERMANENT RIFRAp A 'I. } +4I7f�I I III CONTROI POND WITH......... _ l r LINED CHANNEL l S _ luven-rruvlel: ~. ~ -- 1'"-� } ii�` - ` PERMANENT GRASS iAUlYF S,�W FPIIr]Pf1M1ll ROCKCHCCFCiQN.I - 7 � �,,... V��- } '-ro�Sy Ali, S UNEDGHAMNEL 4 Xj, �- wxix wr.S�x�Eo LEVELSPREADER _ _ �r 5 _ "h_h,_i°*_ - _ '_ I�• may_ L. — __-`I 1 ' _= :57 *y 1� - —� �lll•tflx Gx:.VIRIWYr11JlL LINEo CHANNEL a PROPERTY BOUNDARY INTERIOR WASTE ROCK _ l ' ; PERIMETER BERM 4 Ylr( .YRf w � �N;`,•`- LE ELSPRCADCR `I - "� z_ I''�, ':- ! r+�/ J `�• CULVERT OUTLET _ - __ ^•'sr o' _ _. �{ ��. ��_�� - :::� �'I: �. .�\ � t+'. STABILEATIO4 - �, * {"' f �� t S-' ,�•. . R PERFA+SNENi RIPR:SP c AR - 3 LINED CF WJNEL i TEMPORARY 9ILT - - — — _ --- _�--�_ FENCE CULVERT OUTLET RE1'EGETATEQ $TA,OILIZATI W -- s —�- ,.., ..�. I — CONSTRUCTION — TEMPORARYSILT F ILL SLOPE FENCE CULVERTOUTLE - r � TJ PERMAWENTSEDIMENT L PMP EMERGENCY OONTRDL POLO WITH SIUMMER SPILLWAY ISTING CULVERTS{TYP.I PFRINFi Ad:CFSS ROAD - STAEl1UZATION AND STARTT ER Eh16AMKhE11T y� CONSTRUCTION EROSION CONTROL PLAN PERIk1EFERACCE38 ROAD HIGH POINT ter�ie.r-aa}I FElINL114 K44r 8rw AI��nG}A PIDYIaEr LNTIS TRf nor ocscrsnul ats u....,a`.. .ua xb 9 consulting DRAFT 3.ONTICLIV9RIlRRlRl1' o-uo� .______.—. LOCATION 4F EROSION CONTROLS Ui.012U2i f I KIWI&MOfTAIN WNE � PRELIM NARY ARCHDALE USPR[•]a5M„'w rA UI 4w{, EROSION AND SEDIMENT CQNTROL PLAN omexm.iwwcllroa KING$MOUNTAIN MINE PROJECT FIGURE C-2 FlE-E VEnaMM10 par v rt.r Rdino{W.�� ,we oovme sax.[lo-xmm Source:SRK,2024 Figure 3.1: Archdale Erosion and Sediment Control Plan MH/DH April 2024 SRK Consulting(U.S.), Inc. Erosion and Sediment Control Plan Template—Kings Mountain Page 10 4 Construction Schedule The following sections describe the conceptual construction schedule of the filtered TSF and associated facilities, the operational period of TSF raise construction, and tailings placement within the facility. 4.1 Phase 1 : Site Preparation 4.1.1 Topsoil Salvage and Unsuitable Soil Removal Prior to construction, the access roads, footprint of the TSF, and plant site will be cleared and grubbed of existing vegetation. Organic topsoil and growth media will be stripped and hauled to a designated stockpile, where it will be stored for reuse during the Project closure phase. Unsuitable soils across the site will be removed and hauled to a designated stockpile, where it will also be stored for reuse during facility closure. 4.2 Phase 2: Facility Construction 4.2.1 Perimeter Access Road and Starter Embankment Construction Initial construction of the TSF will include a perimeter access road constructed around the edge of the existing pit, grading for the NPI pad, and a starter embankment completely within the base of the existing pit. Removal of existing unsuitable material in the future embankment and storage area will be completed concurrently with establishment of the base area for the perimeter road, starter embankment, and filtered tailings storage area. Drainage will be established in the interior of the TSF area. Grading for the NPI pad will include 2.5H:1 cut-and-fill side slopes and nominal 2% pad area. The embankment will be constructed with 1.5H:1 V interior side slopes and 2.5H:1 V exterior side slopes. Excavation cut-and-fills for the NPI pad and perimeter access road will be graded and revegetated during the construction phase.The surface of the NPI pad will incorporate a gravel traffic surface,while the perimeter access road will utilize a compacted road base surface. Construction of the contact water pond (CWP) will take advantage of existing topography, with the construction of the pond primarily in cut with a crest width of 25 ft. The pond will be about 15 ft deep with 2.5H:1V side slopes and constructed without a base liner to facilitate periodic sediment cleanout. Construction of the sediment pond will be incorporated in the perimeter corridor berm construction, in the southwest corner of the TSF perimeter to take advantage of an existing 60-inch culvert discharging under 1-85. Waste rock haul for embankment construction will be via over-the-highway haul trucks from the Kings Mountain mine pit about 3 miles northeast of the TSF. Only non-potentially acid generating waste rock will be used for embankment construction. Temporary haul roads will be constructed as necessary within the pit and tailings placement areas to ensure all-weather access for highway and site haul trucks during operations. Tailings haul trucks will access the interior of the TSF via temporary haul roads constructed off of the main site haul road around the southwest corner of the TSF. Grading of the waste rock embankment and subgrade will be constructed to direct runoff and drainage from the waste rock material to the interior of the TSF. MH/DH April 2024 SRK Consulting(U.S.), Inc. Erosion and Sediment Control Plan Template—Kings Mountain Page 11 4.2.2 TSF Interior Base and Side Slope Design The saprolite at the base of the TSF interior will be excavated to an average depth of about 10 ft (except as noted above in the southeast corner of the TSF), shaped to roughly mirror existing topography, and provide a relatively smooth surface sloped to a single seepage collection sump at the southeastern corner of the TSF. Following base grading and compaction, a TSF base drain system will be installed over the prepared TSF base to collect and remove runoff from the TSF base, runoff and seepage from the waste rock perimeter berm, infiltrating meteoric water, and any collected seepage from upwelling groundwater. Groundwater modeling (SRK, 2024) and water balance modeling (SRK, 2024) have determined that a pumping capacity of 200 gallons per minute (gpm) is adequate to evacuate the TSF sump on a daily basis when subjected to the 100-year storm event. To facilitate pumping from the seepage collection sump at the base of the TSF,an 18-inch pipe will be installed along a ramp on the internal embankment side slope down to the seepage collection sump. 4.3 Phase 3: Operations 4.3.1 Raise Construction Raise construction will be an annual exercise throughout the life of the facility.The starter embankment constructed prior to process startup is expected to provide tailings storage capacity for the first year of operation. During that first year of processing, the first annual raise will be constructed, and so on through the sixth year of operation, which will provide sufficient tailings storage capacity through the eighth year of operations. Beginning with the first year of construction after the starter embankment, each annual raise will be a downstream lift constructed from the toe up to and over the crest with run-of-mine waste rock. The crest width will be maintained at 40 ft(including safety berms and travel ways)for each raise. The currently proposed annual construction targets are aimed at providing a minimum freeboard within the TSF embankment above the highest tailings level of 4 ft. Based on the operational methods described below, actual storm storage capacity will be much greater, as the tailings surface will be sloped to manage stormwater at a surface collection sump. During raise construction, grading will maintain containment of runoff and seepage from the waste rock face inwards towards the TSF interior. Once final perimeter grades have been achieved, the exterior slopes of the perimeter berm will be revegetated with a minimum of 2 ft of growth media placed in loose lifts and revegetated with an approved seed mix. Best management practices will be implemented to prevent erosion until vegetation is successfully established. Runoff from the exterior slopes will be collected in the previously constructed perimeter channels as non-contact water, routed to the sediment pond for sediment control prior to release to Archdale Creek. 4.3.2 Tailings Placement and Tailings Surface Management Tailings will be delivered to the site in over-the-highway haul trucks and either placed directly at the working face or deposited in temporary stockpiles for management with TSF haul equipment. Tailings will be spread with dozers into 12-inch-thick lifts and compacted. The end goal of the daily placement and grading work is to create a smooth, compacted surface that will promote stormwater flow to a MH/DH April 2024 SRK Consulting(U.S.), Inc. Erosion and Sediment Control Plan Template—Kings Mountain Page 12 temporary stormwater collection point while minimizing the potential for stormwater to collect and pool anywhere else on the tailings surface. Collected stormwater will be pumped from the collection point at the tailings surface directly to the CWP east of the TSF. Water balance modeling of the TSF (SRK, 2024) estimated that a nominal pump size of 1,200 gpm is capable of evacuating the PMF event from the surface of the TSF within about 2 weeks. Under the 100-year, 24-hour storm event, the 1,200-gpm pumping system will remove the ponded water from the tailings surface in <2 days. 4.3.3 Stormwater Management During operations, all stormwater management will utilize the stormwater management infrastructure developed during Phase 2 (Construction). Operation stormwater management at the proposed Archdale TSF will consist of conveyance of NPI stormwater from revegetated or resurface areas around the site to the 30-or 36-inch culvert discharging under 1-85. Perimeter non-contact water will be collected from the perimeter corridor and reclaimed perimeter berm slopes and managed with the perimeter sediment pond before being discharged to the 60-inch culvert discharging under 1-85. All contact water produced from contact with the tailings or waste rock materials will be temporarily collected in the TSF sumps before being pumped to the CWP for monitoring and release to the 30-inch culvert discharging under 1-85. 4.4 Phase 4: Closure SRK's Preliminary Closure Plan (SRK, 2024b) describes tailings facility closure in more detail, which is currently anticipated to include the formation of a mounded top surface of compacted tailings graded to drain to the TSF perimeter at a minimum surface grade of 3%. A minimum of 2 ft of growth media will then be placed in loose lifts and revegetated with an approved seed mix. Best management practices will be implemented to prevent erosion until vegetation is successfully established. Stormwater berms and channels will be installed as necessary to control stormwater flows off of the closed surface and safely route them into the perimeter stormwater management system; riprap lining or channel erosion protection products will be utilized where necessary to manage the final grading configuration. MH/DH April 2024 SRK Consulting(U.S.), Inc. Erosion and Sediment Control Plan Template—Kings Mountain Page 13 5 Planned Erosion and Sedimentation Control Practices Sediment and control practices will be implemented at the site for individual components of the Project. Some features, such as non-contact discharge structures, are permanent and will remain after the Project enters the post-closure phase. Other features will be in use during the operational period of the mine (approximately 10 years when the development stage is included). Permanent and operational features of the ECP will be implemented as they are constructed in either the development, mining, or closure phases of the Project and are described in detail below. Additional temporary practices are recommended for the individual components as necessary during their initial construction and will be detailed in the individual ECPs that will be developed as the Project advances to the design stage. Activities associated with the Archdale TSF include: • Removal and stockpiling of growth media from the area in the footprint of the TSF • Installation of silt fences, prior to construction,downgradient of the TSF perimeter access road, the NPI area, and the light vehicle access • Management of runoff from active construction areas • Construction of the haul road roadside channel • Construction of the raised berm around the TSF • Stabilization and revegetation of the slopes and grading Specific practice numbers identified in the erosion and sediment control practices reference the NCSCC(2013), Chapter 6, Practice Standards and Specifications.The attached Drawing C-1 presents the location of these facilities and the planned erosion control measure proposed for the Archdale TSF. 5.1 Permanent Development- and Operational-Stage Practices During the pre-development, development, and mining stages of the Project, surface water management structures will be developed to control flows and sediment during the life of the Project (operational) or during operations and through the post-closure (permanent). Operational controls will be removed or reconfigured during the closure stage of the Project. 5.1.1 Permanent Sediment Control Pond Permanent sediment basins are designed to serve areas larger than 5 ac and remain in function for longer than 1 year. One permanent pond will receive non-contact water flows from disturbed and undisturbed natural ground collected by the perimeter channels and release the waters into the existing Archdale Creek. Table 5.1 presents a summary of the sediment pond with its main characteristics. According to the NCSCC (2013), the following design criteria applies to sediment basins (ponds): • The minimum basin volume will be determined based on 1,800-cubic-foot (ft3) of storage per acre of disturbed land. • The minimum surface area will be determined based on 425 square feet (ft2) per cubic foot per second (cfs) of the 10-year peak flow. MH/DH April 2024 SRK Consulting(U.S.), Inc. Erosion and Sediment Control Plan Template—Kings Mountain Page 14 As per the North Carolina Mining Manual, "in the Coastal Plain and Piedmont regions, the above equation has been shown to provide a trapping efficiency of 75% or greater for the 40-micron particle: • At a minimum, design the combined spillway system for the sediment basin to be capable of passing the 25-year storm event for the total drainage area. • The minimum dewatering time for the pond is 48-hrs and will require 3 baffles unless less than 20 ft long." Table 5.1: TSF Sediment Pond Volume and Surface Areas Parameter Value Required Contributing watershed 64 ac Maximum 100 ac Top width 500 ft Top length 90 ft Crest elevation 877 ft Length-to-width ratio 5.6 Minimum 2:1; maximum 6:1 Pond slopes 2H:1V Bottom elevation 865 ft Spillway invert 870.5 ft Depth to spillway 5.5 ft Minimum 2 ft Area at spillway 0.696 ac 0.695 ac Volume at spillway 3.11 ac-ft 2.64 ac-ft Spillway width 50 ft Skimmer size 8-inch float/6-inch orifice Nominal skimmer flow 0.854 cfs/383 gpm Time to dewater 51 hours Minimum 48 hours Source:SRK,2023a The Archdale perimeter sediment pond will receive runoff from up to 65 ac of disturbed land, which includes perimeter roads and berms, haul roads, and other mine disturbed areas. Figure 3.1 shows the location of the pond, which will be configured as a skimmer pond. 5.1.2 Sediment Fence (Practice 6.62) Sediment fences will be placed around disturbed surface during construction activities (as indicated on Figure 3.1) to minimize sediment from entering the non-contact channels. Sediment fences are anticipated during: • Clearing and construction of the TSF • Construction of haul roads, non-contact diversion channels, sediment ponds, and other mine infrastructure • Construction of the process area and non-process area sites 5.1.3 Permanent Grass-Lined Channels (Practice 6.21 and Practice 6.30) Permanent non-contact diversions channels will be constructed to route non-contact flow through the Project area, as described in Section 9.Where calculations indicate that grass-lined channels will have adequate erosion resistance, these channels will be stabilized and revegetated as part of the channel construction. MH/DH April 2024 SRK Consulting(U.S.), Inc. Erosion and Sediment Control Plan Template—Kings Mountain Page 15 5.1.4 Permanent Riprap-Lined Channels (Practice 6.21 and Practice 6.31) Permanent non-contact diversions channels will be constructed to route non-contact flow through the Project area, as described in Section 9. Where calculations indicate that riprap-lined channels will be required to provide adequate erosion resistance, these channels will be constructed with riprap channel armoring. 5.1.5 Permanent Outlet Protection Level Spreader (Practice 6.40) The sediment pond will discharge into Archdale Creek using a skimmer as well as an emergency spillway. The outlet pipe from the skimmer and the discharge from the emergency spillway will both utilize level spreaders at the discharge point into Archdale Creek to minimize erosion. 5.1.6 Operational Dust Control (Practice 6.84) Haul traffic on dirt roads between the mine facilities will be ongoing during the mine development, operations, and closure activities and will require regular application of water for dust control. Dust control water will be supplied by dewatering of the existing pit lakes during construction and placement. Air monitoring will be implemented at the site to evaluate the effectiveness of the dust control and adjust sprinkling application rates as necessary to meet Mine Safety and Health Administration (MSHA) guidelines. 5.1.7 Operational Temporary Seeding (Practice 6.10) Operational stockpiling of growth media will occur throughout the life of the Project as mine facilities are developed or incrementally expanded. Where suitable growth media can be harvested from the surfaces during the facility development, the growth media will be stockpiled in designated areas. The stockpiled growth media will be used during concurrent closure and final closure activities, as described below. As the stockpiles achieve their ultimate shape, the surfaces will be temporarily vegetated to minimize erosion. 5.2 Closure Stage Practices When mine facilities have achieved final surface configuration, it may be feasible to apply progressive closure activities to limited areas of the Project while mining operations are still active elsewhere at the site. Progressive closure plans will be developed as the mine design progresses. Regardless, at the cessation of mining, closure activities will remove operational infrastructure and upgrade or add additional features to the mine facilities to provide for long-term stability. A preliminary closure plan for the facility Project has been developed (SRK, 2024b) and will be refined and updated as the Project design is advanced. General measures that will be included in the mine plan are described in the following subsections. 5.3 Temporary Development Stage Practices During all stages of the Project, mine facilities will be developed, which will include clearing and grubbing, growth media removal and stockpile, grading, and establishing permanent or semi- permanent surfaces. As the final designs for these activities are developed, individual ECPs will be developed that implement temporary sediment control measures necessary until the permanent or operational controls are in place. MH/DH April 2024 SRK Consulting(U.S.), Inc. Erosion and Sediment Control Plan Template—Kings Mountain Page 16 5.3.1 Temporary Dust Control (Practice 6.84) Dust control during the construction of the mine facilities will be addressed through the regular sprinkling of water on the surfaces. A fleet of water trucks equipped with sprinkler attachments is included in the mine operational fleet and will be utilized to limit dust during earthworks activities. 5.3.2 Temporary Sediment Traps (Practice 6.60) Temporary sediment traps consisting of rockfill berms will be placed in the diversion channels to control sediment releases until vegetation can be established in the disturbed area. 5.3.3 Sediment Fence (Practice 6.62) Sediment fences will be placed around disturbed surface during construction activities prior to revegetation to minimize sediment from entering the non-contact channels. MH/DH April 2024 SRK Consulting(U.S.), Inc. Erosion and Sediment Control Plan Template—Kings Mountain Page 17 6 Maintenance Plan Regular maintenance practices are important to prevent adverse negative impacts to the environment. Routine inspections of all sediment control facilities will be conducted at least once per week and after every rainfall event that results in observable runoff. An inspection report template will be prepared. Based on the observations, the following activities will be conducted. • Sediment pond: o All erosion and sediment control measures, including the sediment pond, seepage ponds, check dams, and silt curtains, will be checked for stability and operation. Any needed repairs or adjustments will be implemented immediately. o The sediment pond will be cleaned out when the sediment accumulation reaches 50% of the available storage. The cleanout level will be pre-determined in the inspection report. o Floating trash and debris will be removed. o Vegetation at the top and faces of the embankment will be removed. o All outlet structures from the sediment pond will be inspected for clogging and/or structural damage. Debris will be removed, and any repairs needed will be done immediately. Outflow locations will be inspected to make sure tailwater conditions are not impeding discharge from the pond. • Check dams: o Remove sediment adjacent to and accumulated behind check dams before it reaches halfway to the top of the dam. o Restore dislodged or washed-out check dams to their original configuration. o Fill in or otherwise repair areas where check dam undercutting or bypasses have occurred. o Add stones to dams as needed to maintain design height and cross-section. Use larger stone, if necessary, to counter higher-than-expected flow velocities. o Repair ditch/channel areas where excessive downcutting or side scour have occurred. o Make notes on whether the selected configuration is preventing channel erosion. If not, make the necessary changes to the design, considering other materials or closer spacing in areas experiencing the most problems. o If significant erosion is observed between dams, install a protective turf reinforcement mat or section of riprap liner in that portion of the channel. o Replace rock weirs when filtering capacity is reduced by one-half. • Riprap channels: o Riprap channels will be inspected at least once per year and after every major storm event for displaced stones, slumping, and erosion at edges, particularly in steeper segments. o Woody vegetation will be annually removed from the riprap to avoid potential impacts associated with the roots, such as dislodgement of rocks. • General guidance: o Field markers will be placed to denote areas of concern and in need of repairs or maintenance. o A plan to access appropriate riprap (e.g., on-site stockpiles) will be in place to allow for timely repairs of eroding channels. o For each inspection, the inspector should bring a copy of the as-built drawings to mark potential corrections and problem areas. The marked-up drawings will be stored digitally MH/DH April 2024 SRK Consulting(U.S.), Inc. Erosion and Sediment Control Plan Template—Kings Mountain Page 18 to confirm that the works needed were completed in subsequent inspections. The reports will also include photographic records to document the following: - Vehicle access - Overview of facility - Overview of spillway - Overview of discharge infrastructure - Upstream view of the facility - Downstream view of the facility MH/DH April 2024 SRK Consulting(U.S.), Inc. Erosion and Sediment Control Plan Template—Kings Mountain Page 19 7 Detail Drawings and Specifications for Practices Specified References have been made to specific sections of the NCSCC. Detail drawings and specifications will be provided in the next stage of design. This section includes preliminary sketches to illustrate the recommended practices. Figure 7.1 shows a typical drawing of a permanent skimmer basin, representative of the sediment pond. Calculations to support the design of the Sediment Pond are presented in Appendix B of the main report(Table 6). 5MMMER SEDIMENT BASIN PLAN VIEW BAFFLE �I�llj�I�llj 3RD BAFFLE: DESIGN CRITERIA I1=— =— —I — SURROUNDING MIN. SKIMMER LENGTH TO 2:1 — WIDTH RATIO NOTES: Max LENGTH TO fi:1 WIDTH RATIO 1 REFER ADDfTIONOAL MS4 FOR DESIGN SEDIMENT U F VOLUM�RAGE CU FF. INFLOW SPECIFICATI___ BARREL RECARDNG SNS EDIMENT VOLUME PER AC. STRUCTURE REQUIRED DISTURBED 10� - -- PIPE BASINS_ 180D MIN. DEWATERING CU.FF =_ -_ 2. FORERAY, IF REQUIRED _____ VOLUME (67 CU.7C.) BY M54, IF NOT ADD REQUIRED PER AC. ISER THIRD BAFFLE. TOTAL SURFACE 325 SKIMMER AREA SQ.FT.PER ATEDEVICERING ICI REQUIRED CFE 010 MINIMUM — DEWA7ERINC 48 HRS TIME _ F EQUAL MAXIMLM WIDTH ALLUWEB MUST DEWATERING 120 HRS _ CONFIRM MEETS TIME — — — — FLOW RATE RANGE CROSS—SECTION VIEW SEE NDTE 02 —IIII�III— - — SPECIFIED, OEWATER140 ZONE PRIMARY SPILLWAY(RISER) 5' MIN NORMAL WATER EMBANKMENT INFLOW ELEV. STRUCTURE 1.0, MIN. BAFFLE 'MIN. OUTLET INVERT — — FREEBOARD SEDIMENT DEW TIERING BASIN STORAGE VOL. VOLUME NU. REQ. PRPV, REQ. PROV, III—III—III— — — — EMERGENCY (OF) (CF) (CF) (CF} T��I�ILTIII_ _ _ I—III— — i 1 1 I, — III — I I— r' FILTER FABRIC ANTI-SEEP SEDIMENT NOT TO SCALE DATA BLACK STORAGE ZONE BOTTOM BASIN ELEv. BASIN EASIN DRAINAGE JISTJR3EJ Qe SURFACE AREA BOTTOM OUTLET BARREL Top OF EVE,. EMER. SKIMMER SKIMMER SKIVMES EUUAL SKIMMER NO AREA AREA (CFS) REQ- PROV OF BASIN INVERT PIPE USER SPILLWAY SPILLWAY SIZE ORIFICE TYPE ALLOWED" FLOW RATE (ACRES) (ACRES) (" (CF} (ELEV,) (ELE V.) (SIZE) (ELEV) [ELEV.) [WIDTH) DIAMETER YES NO MIN. MAX. MARLEE MARLEE RYMAR WWW.��5)—ERWRD33S.COM SKIMMER & RISER SEDIMENT BASIN WITH PERMANENT WET POND REV 12 04 22 Source: Rymar Float,2024 Figure 7.1: Skimmer and Riser Sediment Basin with Permanent Wet Pond Figure 7.2 shows check dams, and Figure 7.3 shows permanent and operational riprap-lined channels (Practice 6.21 and Practice 6.31). MH/DH April 2024 SRnConevmng(U.S.), Inc. Erosion and Sediment Control Plan Template—Kings Mountain Page 20 L = The distance such that points A and B are of equal elevation 15 min. 9"min At Filter Cloth Plan View washed stone 15 center Fi[ter Cloth Cross-5ection View Source: wCSCC.co1n Figuna7.2: Rock Check Dam mmov Apm2024 SRK Consulting(U.S.), Inc. Erosion and Sediment Control Plan Template—Kings Mountain Page 21 Trapezoidal Riprap Channel Design top width Design depth y:4 11 Oil- Filter layer, gravel or fabric Source: NCSCC,2013 Figure 7.3: Typical Riprap Channel Cross-Section Figure 7.4 shows permanent and operational outlet stabilization structure (Practice 6.41), and Figure 7.5 shows operational paved flume (Practice 6.33). MH/DH April 2024 SRK Consulting(U.S.), Inc. Erosion and Sediment Control Plan Template—Kings Mountain Page 22 Pipe Outiat to Flat Area— No Well defined Channel 3d0 A A do Plan If La ,�L Ik=II �ITI�Ad u lali�l` r. I Section AA *Filter Notes blanket i. La is the length of the riprap Pipe Outlet to Well-defined apron. Channel 2- d= 1.5 times the maximum stone diameter but not less than 6"_ 3. In a well-defined channel ex- tend the apron up the channel banks to an elevation of 6" A A ---- above the maxim urn tailwater depth or to the top of the bank, whichever is less. 4. A filter blanket or filter fabric should be installed between Plan the riprap and soil foundation. ;¢ La �a I Ad_EI ` N-IR , �4111i1 'II Section AA �I I uti 41i1� Filter blanket Figure 6.41c Riprap outlet protection(modified from Va SWCC). Source: NCSCC,2013 Figure 7A Outlet Stabilization Structure MH/DH April 2024 SRK Consulting(U.S.), Inc. Erosion and Sediment Control Plan Template—Kings Mountain Page 23 Emergency ,,1`4,`A; bypass flowIN !��, �'�:• 1., - ,,� n.��'xt1�`1A `�,1, r'�• •\tom�`` \`.��:SIB` -• . Is vV r. r Expansion joint Source: NCSCC,2013 Figure 7.5: Typical Operational Paved Flume MH/DH April 2024 SRK Consulting(U.S.), Inc. Erosion and Sediment Control Plan Template—Kings Mountain Page 24 8 Vegetation Plan In accordance with the North Carolina Application for a Mining Permit, a reclamation plan must include plans for year-round seeding, including the time of seeding and the amount of seed, type of seed, fertilizer, lime, and mulch per acre. The recommendations must include general seeding instructions for both permanent and temporary revegetation. Table 8.1 includes a preliminary seed mix and schedule provided by SWCA Environmental Consultants (SWCA) (2023). Table 8.1: Preliminary Seed Mix Composition and Schedule Seed Mix Type Seeding Dates Seeding Rates NC Steep Slope Mix ERNMX-310 All dates 45 pounds Ib/ac Native Habitat Strip Mine Mix ERNMX-111 All dates 20 Ib/ac Native Steep Slope w annual rye ERNMX-181 February 15 to August 15 60 Ib/ac Native Steep Slope w grain rye ERNMX-181-2 August 15 to February 16 75 Ib/ac Source:SWCA,2023 Temporary cover species for erosion control will include: • Brown Top Millet: February 15 to August 15, 20 Ib/ac • Annual Rye Grain: August 15 to February 15, 30 Ib/ac No fertilizer is recommended at the site due to the success of volunteer regrowth seen during site visits.Seed will be procured from Ernst Conservation Seeding or another approved seeding contractor. Wildlife habitat is typically established by creating ecosystems of native species and reshaping landscapes to create suitable habitat. Monitoring and measurement criteria for vegetation and wildlife success will be developed as mine plans progress. MH/DH April 2024 SRK Consulting(U.S.), Inc. Erosion and Sediment Control Plan Template—Kings Mountain Page 25 9 Supporting Calculations Hydrological and hydraulic calculations were primarily conducted using a HEC HMS model developed for the Project and are included as appendices to the storm water management plant. Appendix B of that document presents a summary of hydrological and hydraulic calculations and modeling results used for the design of erosion and sediment control measures. MH/DH April 2024 SRK Consulting(U.S.), Inc. Erosion and Sediment Control Plan Template—Kings Mountain Page 26 10 Financial Responsibility/Ownership Form MH/DH April 2024 SRK Consulting(U.S.), Inc. Erosion and Sediment Control Plan Template—Kings Mountain Page 27 11 Checklist MH/DH April 2024 SRK Consulting(U.S.), Inc. Erosion and Sediment Control Plan Template—Kings Mountain Page 28 12 References Environmental Systems Research Institute, Inc. (ESRI), 2023. Garrett, 2004. Global Industry Standard on Tailings Management (GISTM), 2020. Horton and Butler, 1988. North Carolina Erosion and Sediment Control Planning and Design Manual (NCSCC), 2013. North Carolina Sedimentation Control Commission, North Carolina Department of Environmental and Natural Resources, and the North Carolina Agricultural Extension Service. Erosion and Sediment Control Planning and Design Manual, May 2013. North Carolina Surface Mining Manual, 1996. State of North Carolina, Department of Environment, Health and Natural Resources, February 1996. SRK Consulting (U.S.), Inc. (SRK), 2023. SRK, 2023a. SRK, 2024. SRK, 2024a. Design of the Archdale Tailings Facility, March 2024. SRK, 2024b. Conceptual Report Closure Plan Kings Mountain Mining Project September 2023 Rymar Float, 2024. Webpage: https://rvmarwaterworks.com/marlee-float. SWCA Environmental Consultants (SWCA), 2023. Biological Resources Summary Report for the Kings Mountain Lithium Mine, Cleveland County, North Carolina Interim Draft, prepared for Albemarle U.S., by SWCA Environmental Consultants, Colorado, April 2023. MH/DH April 2024 SRK Consulting(U.S.), Inc. Erosion and Sediment Control Plan Template—Kings Mountain Page 29 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. MH/DH April 2024