Perpetua Resources Corp. · TSX:PPTA
Perpetua Resources — Technical Presentation (July 2021)
66 slides from Perpetua Resources's technical presentation, Jul 8, 2021
Slide 1: Stream Restoration Webinar, July 2021
S t r e a m R e s t o r a t i o n We b i n a r, J u l y 2 0 2 1 TSX :P P TA N A SDA Q:P P TA PERPETUA RESOURCES C r i t i c a l R e s o u r c e s . R e s p o n s i b l e M i n i n g . E n v i r o n m e n t a l R e s t o ra t i o n . www.perpetuaresou rc e s.c om
Slide 2: The Stibnite Gold Project
THE STIBNITE GOLD PROJECT We can take an area abandoned after 100 years of mining activity and use a sustainable approach to restore the environment and develop a modern mining project with critical mineral production. 2
Slide 3: Stibnite Gold Project
STIBNITE GOLD PROJECT Coeur d’Alene Stibnite Gold Project Perpetua Resources Au-Sb 84 road miles from Cascade 3
Slide 4: Restoration
RESTORATION 4
Slide 5: Stream Design
STREAM DESIGN Goal: Reclaim and/or restore disturbed streams and floodplain from historical and proposed mining activities to improve habitat conditions for aquatic species and mitigate for project impacts. Stream Design Report: Section 1.3 5
Slide 6: Reclamation Restoration
Reclamation Restoration stable, static, little to naturally dynamic, no change; may not deformable, mimic natural resilient; mimics conditions natural conditions Yankee Fork of the Salmon River, Idaho Perpetua Resources has committed to a RESTORATION standard wherever possible. 6
Slide 7: 13.3 km perennial streams
13.3 km 19.6 km 20.3 km perennial perennial perennial streams streams streams historically proposed proposed impacted impacted restored 7
Slide 8: Current Conditions
CURRENT CONDITIONS Existing Yellow Pine pit EFSFSR • East Fork South Fork Salmon River (EFSFSR) dumps into Yellow Pine pit Fish Barrier • Fish passaged blocked • Sediment from Blowout Creek settles in Yellow Pine pit Yellow Pine Pit 8
Slide 9: During Mining
DURING DURINGMINING MINING Interim Fish Passage • Tunnel, 0.9-mile long • Fish re-connected to native spawning grounds for the first time in over 80 years. 9
Slide 10: Stream Access Restoration and Enhancement
STREAM RESTORATION AND ENHANCEMENT Restore Passage at Backfilled Yellow Pine Pit Stream Restoration and Enhancement (ModPRO – Alt 2) Restoration • 20.6 km of restored/enhanced perennial streams Enhancement • 5.5 km of restored non-perennial New Barrier at streams STREAM ACCESS Tailings Facility Rest
Slide 11: Access Upper EFSFSR
ACCESS UPPER EFSFSR 11
Slide 12: Stream Design Process
STREAM DESIGN PROCESS • Project area reach delineation • Reference site analysis • Develop physical design criteria o Reference site data o Empirical formulae o Published design guidelines • Assign biological objectives based on fish habitat preferences • Refine design criteria to maximize habitat b
Slide 13: Stream Design Process
STREAM DESIGN PROCESS Riordan Creek – Dammed by Landslide 6600 Low gradient 6500 6400 Dam crest Reference Site Examples 6300 6200 6100 6000 21000 22000 23000 24000 25000 26000 27000 28000 29000 30000 31000 Hell Roaring Creek – Dammed by Glacial Moraine 7300 7200 Low gradient Riordan Creek 7100 7000
Slide 14: Backfill and Restoration Beginning in Year 7
BACKFILL AND RESTORATION BEGINNING IN YEAR 7 14
Slide 15: EFSFSR Over Yellow Pine Pit, Blowout Creek, Meadow Creek Over TSF
EFSFSR Over Yellow Pine Pit Blowout Creek 13.3 km 19.6 km 20.3 km perennial perennial perennial streams streams streams historically proposed proposed Meadow Creek impacted impacted restored Over TSF 15
Slide 16: Restore EFSFSR Over YPP
RESTORE EFSFSR OVER YPP Restoration Objectives • Restore migratory fish passage through YPP to upstream reaches • Target isolated spawning and rearing habitat creation • Allow geomorphically appropriate natural channel process (migration, avulsion, scour, deposition) • Increase hydraulic and geomorp
Slide 17: Restore Meadow Creek Over TSF
RESTORE MEADOW CREEK OVER TSF Tailings Storage Facility (TSF) Restoration Objectives • Target highly sinuous, low-gradient, meadow-like conditions (based on equilibrium slope evaluation) • Allow natural channel process (migration, avulsion, scour, deposition) • Provide accommodation space for antici
Slide 18: Restore Blowout Creek Existing Condition
RESTORE BLOWOUT CREEK EXISTING CONDITION 18
Slide 19: Restore Blowout Creek
RESTORE BLOWOUT CREEK Restoration Design Stabilize Slopes • Rock drain base • Fill against toe of slope • Provide overflow channel 19
Slide 20: Restore Blowout Creek
RESTORE BLOWOUT CREEK Restore Incised Stream and Wetland 20
Slide 21: Stream Functional Assessment
STREAM FUNCTIONAL ASSESSMENT Framework – Elements Evaluated to Calculate Reach Functional Index The SFA uses a modified version of the Watershed Condition Indicators Matrix (WCI Matrix) (USFS 2003, 2010) along with several fish use indicators to evaluate stream condition by measuring up to 20 elemen
Slide 22: Stream Functional Assessment: Functional Units
STREAM FUNCTIONAL ASSESSMENT Framework – Functional Units Measured using Functional Units (FU): Quality Quantity Where: FU = Functional Units FI = Functional Index The functional unit is the mitigation currency proposed for the SGP such that subtracting the functional units calculated for the baseli
Slide 23: Stream Functional Assessment Results
STREAM FUNCTIONAL ASSESSMENT Results 23
Slide 24: EFSFSR and Meadow Creek
EFSFSR and MEADOW CREEK Restored/Enhanced EFSFSR and Meadow Creek • Passage enhancements • Blowout Creek no longer contributing excess • Engineered log jams sediment • Other spawning and rearing habitat • Spent leach ore and Bradley tailings no longer enhancements contributing metals loading Example
Slide 25: Restoration: East Fork South Fork over Yellow Pine Pit
RESTORATION East Fork South Fork over Yellow Pine Pit 25
Slide 26: Stream Design Process
STREAM DESIGN PROCESS Reach Delineation • Stream Design Approach: • Same process for all streams • Project Area reach delineation • Reference site analysis • Develop physical design criteria • Reference site data • Empirical formulae • Published design guidelines • Assign biological objectives based
Slide 27: Stream Design Objectives
STREAM DESIGN OBJECTIVES General Stream Design Objectives Stream Design Project Area • Provide fish passage above Yellow Pine pit • Restore high-quality stream channels over the top of proposed mine features at closure • Develop a stable yet functionally dynamic and resilient stream channel and floo
Slide 28: Stream Design Objectives
STREAM DESIGN OBJECTIVES Reach-Specific Stream Design Objectives • Biological (species of interest: Chinook salmon, steelhead, bull trout, and Westslope cutthroat trout) • Fish Distribution • Fish use periodicity • Habitat Requirements • Intrinsic Potential (Anadromous Salmonids) • Physical (natural
Slide 29: Stream Design Process
STREAM DESIGN PROCESS Stream Design Approach: • Same process for all streams • Project Area reach delineation • Reference site analysis • Develop physical design criteria o Reference site data o Empirical formulae Including Watershed o Published design guidelines Condition Indicators • Assign biolog
Slide 30: Stream Design Criteria
STREAM DESIGN CRITERIA Riordan Cr. Reference Site #17 Stream Design Approach • Geomorphic Targets • Assume low-gradient habit is less common and more valuable than high-gradient habitat • Maximize low-gradient habitat by increasing slope and decreasing length of high- gradient reaches • Develop mead
Slide 31: Stream Design Criteria
STREAM DESIGN CRITERIA Stream Design Approach • Physical Design Criteria • Floodplain width (1.25 to 2.0 x belt width) Belt Width = Maximum amplitude • Channel capacity (1.5 year discharge) • Bed stability • Alluvial = stable at 1.5 year discharge • Threshold = stable at 100 year discharge Amplitude
Slide 32: Stream Design Criteria
STREAM DESIGN CRITERIA Hydrology/Hydraulics Manning’s n-value (roughness) Estimates Stream Design Approach • Hydrology • 1.5 year (bankfull) discharge design flow • Hydraulics • Roughness • Normal depth at-a-station calculations • Sediment transport (incipient motion) • Stream type Bankfull width re
Slide 33: Stream Design Criteria: Stability Analysis
STREAM DESIGN CRITERIA Stability Analysis Stream Design Approach Stream Design Report: Section 3.3.6, Appendix E • Engineering stability analysis • Bed, bank, and riffle material sizing • Rock armor and grade control material sizing • Select appropriate bank treatments • Wood and log jam structures
Slide 34: Stream Design Criteria: Biological Objectives
STREAM DESIGN CRITERIA Biological Objectives Stream Design Approach • Same process for all streams • Project Area reach delineation • Reference site analysis • Develop physical design criteria • Reference site data • Empirical formulae • Published design guidelines • Assign biological objectives bas
Slide 35: Stream Design Criteria: Biological Objectives
STREAM DESIGN CRITERIA Biological Objectives Stream Design Approach • Same process for all streams • Project Area reach delineation • Reference site analysis • Develop physical design criteria • Reference site data • Empirical formulae • Published design guidelines • Assign biological objectives bas
Slide 36: EFSRSR over YPP Step Pool Reach Plan View
STEP POOL REACH PLAN VIEW ‘NTS ores - THALES AD AT TE LOCITONS SHOWN NONOUR. REACH CERIEW PLAN SETS 12 ROME SiG FOR TIAL FOOL AME PLE GROSS SECTONSFGASED GN CANNEL POTN (MMA) MOCK ARMOR LANE TO SPAN VBLLEY MOTH, AS SOM AT SWATEGE (OOATUNS (TO) ALG (O¥OTIOWN EFS — STEP POOL REACH PROPOSED CHANNEL IIT
Slide 37: EFSFSR Over YPP
EFSFSR OVER YPP Floodplain is 5-10x the bankfull channel width EFSFSR over YPP Example Proposed Stream Liner Details (DRAFT) Layers of Material Over the Liner Total Liner Depth Approximate Reach Mine Facility Protection Armor Layer Stream Bed and Below the Floodplain Liner Width (ft)* (Transition) L
Slide 38: Performance Criteria
PERFORMANCE CRITERIA Overall Performance Standards • From the CMP (March 8, 2019) section 11.1 • Stream Design (as-built conditions) • Physical Channel Conditions • Riparian Vegetation • Functions and Values • Evaluated using Stream Functional Assessment Note: Timeline based on year of specific reac
Slide 39: Stream Functional Assessment
STREAM FUNCTIONAL ASSESSMENT To comply with federal regulations implementing Section 404 of the CWA (33 CFR § 332.3(a); 40 CFR § 230.93), a stream functional assessment tool is needed to demonstrate that all compensatory mitigation requirements are satisfied by the SGP and any aquatic resource funct
Slide 40: Stream Functional Assessment
STREAM FUNCTIONAL ASSESSMENT The Stream Functional Assessment (SFA) Ledger was developed in coordination with natural resource management and regulatory agencies to be used for the Stibnite Gold Project (SGP) to: • Track the impacts/benefits to streams before, during and after mining following resto
Slide 41: Stream Functional Assessment
STREAM FUNCTIONAL ASSESSMENT The SFA Ledger is a computational tool (Microsoft Excel spreadsheet) by which baseline and proposed (interim and restored) conditions can be compared across a variety of spatial and temporal scales to evaluate how stream and floodplain conditions are expected to change a
Slide 42: Stream Functional Assessment: Elements
STREAM FUNCTIONAL ASSESSMENT Framework - Elements The SFA uses a modified version of the Watershed Condition Indicators Matrix (WCI Matrix) (USFS 2003) along with several fish use indicators to evaluate stream condition by measuring up to 20 elements that reflect specific functional indicators. 42
Slide 43: Stream Functional Assessment
STREAM FUNCTIONAL ASSESSMENT The 20 elements analyzed within the SFA Ledger are based on field data, GIS desktop analysis, modeling estimates and professional judgment • Baseline data were collected between 2012 and 2019 from a number of sources and originated from on-site monitoring data or direct
Slide 44: Framework: SFA Reach Generation
STREAM FUNCTIONAL ASSESSMENT Framework – SFA Reach Generation • The SFA Ledger evaluates and compares measured or estimated baseline conditions for each element with proposed future conditions in which debits (impacts) and credits (mitigation) are quantified over time within a consistent reach or ar
Slide 45: Consistent Reaches
STREAM FUNCTIONAL ASSESSMENT Consistent Reaches Example SFA reach delineation combining hypothetical reaches across phases where reach breaks per phase are identified by black dots on the blue stream line, while the combined reach breaks for the SFA are identified by dashed vertical lines spanning e
Slide 46: Framework: Element Scoring Criteria
STREAM FUNCTIONAL ASSESSMENT Framework – Element Scoring Criteria Indicator Element o Rearing Rating FA ≤12 FR >12 – ≤15 UR >15 Temperature ( C) Spawning ≤12 >9 – ≤10 >10 Water Quality Granitic Basin <12% 12% - 18% >18% Fine Sediment (%) Non-Granitic Basin < 3% 3% - 6% >6% Chemical Contaminants (# E
Slide 47: Framework: Functional Quality and Quantity
STREAM FUNCTIONAL ASSESSMENT Framework – Functional Quality and Quantity Reaches can be evaluated by both the Functional Index and the Functional Units • The Functional Index represents the relative functional character of the stream reach regardless of its size (i.e. quality) • The stream order is
Slide 48: Framework: Functional Index
STREAM FUNCTIONAL ASSESSMENT Framework – Functional Index Functional Index (FI) is the normalized weighted average score of scorable elements within each reach as seen in the formula below. Where: FI = Functional Index EWi = Weight of Element i Ei = Score of Element i (1, 2 or 3) Reach score = (sum
Slide 49: The Plan of Restoration & Operations
PLAN ofOF 6 YEARS Study and Engineering49 RESTORATIO 4 YEARS The Plan of of Regulatory Review under NEPA (National Environmental Policy Act) N & 75-DAY Restoration & OPERATIONS Public Comment Period for the Draft Environmental Impact Statement (DEIS) Operations (PRO) PLAN DESIGNED TO: (PRO) • Provid
Slide 50: NEPA at Work
NEPA AT WORK Public feedback and refinement create the best plan. T R A N S PA R E N C Y : 7 5 - D a y P u b l i c C o m m e n t P e r i o d REF I NEMENT: Agencies Responding to the Public Now, the U.S. Forest Service and cooperating agencies will: • Review all comments • Respond to the public • Inc
Slide 51: Improvements
IMPROVEMENTS Add Stibnite Lake (YPP) ✓ Fiddle DRSF eliminated ✓ Add Stibnite Lake on YPP backfill Eliminate Fiddle Added measures to DRSF, add GMS reduce stream temp ✓ Enhanced riparian planting prescription ✓ Smaller Hangar Flats pit (HFP), complete backfill of HFP ✓ No rapid infiltration basins (R
Slide 52: Permitting – Next Steps
EI S: Env ironm e nt al Im p act S t at e m e nt PERMITTING – NEXT STEPS DEI S: Draf t Env ironm e nt al Im p act S t at e m e nt F EI S: F inal Env ironm e nt al Im p act S t at e m e nt NOA : Not i c e of Av ai l ab i l i t y P RO: Plan of Re st orat ion and Op e rat ions ROD: Record of Decision N
Slide 53: Water Quality Today
WATER QUALITY TODAY Water quality monitoring program Baseline groundwater and surface water monitoring program initiated in 2011 and is ongoing • CERCLA and NEPA compliant data QA/QC • 32 perennial stream surface water monitoring locations • 23 surface water seeps, adit seeps and other mining featur
Slide 54: Water Quality Today
WATER QUALITY TODAY Bradley Dumps Meadow Creek, circa 1940s West End Pit Upper Meadow Creek Tailings “Bradley Tailings” Yellow Pine Pit Smelter Meadow Construction Site Creek Mine Heap Leach Pad On/Off Pads Smelter Area YP-T-22 54 S.O.D.A
Slide 55: Water Quality Today
WATER QUALITY TODAY Bradley Dumps Bradley Pit, circa 1940s West End NW Pit Bradley Dump Yellow Pine Pit Meadow Bradley Pit Creek Mine On/Off Pads Smelter Area YP-T-22 55 S.O.D.A
Slide 56: Water Quality Today: Summary of Findings
WATER QUALITY TODAY Summary of findings • Arsenic and antimony are key COIs • Arsenic and antimony concentrations generally show inverse • Meadow Creek and Bradley Pit reach are significant relationship with discharge sources of arsenic and antimony • WQ data from non mining impacted areas show elev
Slide 57: Meadow Creek Valley
MEADOW CREEK VALLEY Surface water impacts Historical placement of spent ore over Bradley Panoramic View of Meadow Creek Valley looking west Tailings (SODA) South North Former Spent Blowout Mill and SODA Ore Creek Smelter SMI Leach Hecla Heap Leach Bradley Pads Tailings YP-T-22
Slide 58: Meadow Creek Water Quality
MEADOW CREEK WATER QUALITY Upstream and downstream Bradley tailings and SODA Meadow Creek below Keyway Marsh 36.0 µg/L As mean 6.1 µg/L Sb mean Arsenic and antimony 2.0 ng/L Hg mean concentrations increase substantially adjacent to and downstream of Bradley tailings and SODA Meadow Creek Meadow Cree
Slide 59: Hangar Flats Area
HANGAR FLATS AREA Surface water quality Modest changes in metal concentrations in Meadow Creek Meadow Creek below Leach Pads 36.2 µg/L As mean 8.2 µg/L Sb mean 8.7 ng/L Hg mean Meadow Creek below Keyway Marsh 36.0 µg/L As mean 6.1 µg/L Sb mean 2.0 ng/L Hg mean 59
Slide 60: East Fork South Fork Above YP Pit
EAST FORK SOUTH FORK ABOVE YP PIT Surface Water Impacts Southeast Southwest Photo Upper EFSF Meadow Creek Legacy Camp dumps adjacent to EFSF DMEA Dump MGI Facilities East Fork Dumps YP-SR-8 EFSF Valley looking south
Slide 61: East Fork South Fork Through YP Pit
EAST FORK SOUTH FORK THROUGH YP PIT Surface Water Impacts Photo Midnight Hennessey Creek Creek YP-SR-6 Bradley Pit Smelter Waste Repository YP-SR-6 Bradley Pit EFSFSR Northwest Bradley Dump YP-SR-4 EFSF Valley looking south Bradley Dumps looking south along the EFSF
Slide 62: Water Quality
WATER QUALITY EFSFSR EFSFSR Downstream of Yellow Pine Pit 67.2 µg/L As mean 31.3 µg/L Sb mean 4.14 ng/L Hg mean EFSFSR Upstream of Yellow Pine Pit 31.6 µg/L As mean 19.5 µg/L Sb mean 3.99 ng/L Hg mean 62
Slide 63: Water Quality Today: Constituent Loading Estimates
WATER QUALITY TODAY Surface Water dissolved constituent loading estimates – 2014 • Discharge estimates used for each sampling location to calculate constituent loads • 2014 data generally representative and captures peak runoff Adits 1% Tributaries Adits 7% 1% Tributaries Sugar 13% Creek 8% Meadow C
Slide 64: Water Quality Today: Groundwater
WATER QUALITY TODAY Groundwater downgradient of legacy mining impacts frequently exceed water quality guidelines for As, and Sb, as well as Mn, Fe, and Al Keyway Dam Post 1970 fill Airstrip Box Culvert SODA Tailings GESTRIN Bradley Valley Fill Tailings Sediments Meadow Creek Valley Cross Section Loo
Slide 65: Natural Background Water Quality
NATURAL BACKGROUND WATER QUALITY Water in mineralized areas is naturally elevated in metals Yellow Pine & West End Perpetua Resources Exploration Sampling of soils and stream sediments delineates a broad region of naturally occurring mineralization with elevated arsenic, antimony, sulfur and mercury
Slide 66: Natural Background Water Quality
NATURAL BACKGROUND WATER QUALITY Natural Background Natural Background Water in mineralized areas is naturally Conditions in Conditions in ID chronic criterion for elevated in metals Groundwater Seepage from aquatic life; Mineralized Areas (150 ug/L Arsenic) 300 Site Characterization studies prepare
Perpetua Resources — Technical Presentation (July 2021) on 6ix