U.S. GOLD CORP.

13 MINING METHODS

Open pit, surface mining is the selected mining method for the Project. This mining method is selected based on the size, shape, location, and value of the mineralization on the property. The Project’s disseminated type mineralization has a large extent and is located near to or outcropping at surface. Additionally, open pit optimizations attempting to maximize the recovery of the in-situ resource show economic excavation results using current project parameters and base case metal prices.

Surface mining is a cyclical process where the four main tasks including drilling, blasting, loading, and haulage are occurring concurrently at different areas of the property. In areas to be excavated vertical blast holes are drilled in a regular pattern and charged with blasting agents. The material will be blasted, loaded into 100 st class rigid frame haul trucks, and transported based on material type to one of four different locations, Run of Mine (RoM) Crusher Stockpile, Co-Disposal Tailings Facility, Ore Stockpile or Waste Rock Facility. Wherever possible Crusher Stockpile ore will be directly fed into the primary crusher at the process plant.

Piteau Associates (Piteau) conducted a geotechnical investigation for the project. Piteau issued a technical memorandum dated September 6, 2022, titled “Recommended Feasibility-Level Geotechnical Slope Designs for the Copper King Open Pit.” This section contains a summary of the report. Following the September 6 report, an updated May 1, 2024 report was completed due to the change in bench height from 20 ft to 30 ft.

The following list summarizes the scope of work that Piteau performed as part of the geotechnical investigation:

Table 13.1 and Figure 13.1 outline the latest slope design recommendations and pit design sectors based on the 30 ft bench design. These sector recommendations have been slightly refreshed for the 2026 feasibility study based on updated geological model for Metasedimentary-Metavolcanic rock unit (MSED).

Table 13.1: Recommended Slope Designs for Presplit Blasted Benches

The following sections contain a summary of the General Recommendations.

Where a range of inter-ramp angle (IRA) is indicated between adjacent design sectors, blending should occur within the design sector with the steeper (greater) design IRA. Similarly, blending from weaker to stronger materials should occur in the stronger (better quality) rock mass materials.

In the early stages of mining below the overburden and weathered bedrock horizon, benching trials for 80 ft high benches should be considered in areas where bench performance is expected to have the least impact on the stability of haul roads or other critical slope areas to confirm that structural continuity of adversely oriented joint sets is limited and therefore has limited impacts on the bench designs. Bench designs should be updated based on ongoing evaluation of bench performance.

At the transition from single- to triple-benches, the triple-bench catch bench width should be implemented at the crest level of the first triple-bench to avoid steepening the design IRA.

Figure 13.1: Pit Sectors and Recommended Slopes

Source Piteau Associates, 2022

The following recommendations are made with respect to the potential for benches to be excavated up to 90 ft high:

Figure 13.2: Design Face (Df) versus Face Condition (Fc) Chart

As a general comment for future advancement of the Project, it is recommended that any new pit designs or significant revisions to the mine plan (for example to the bench, inter-ramp or overall slope angles or heights) be forwarded to Piteau for review, conformance check, and comment. Additional geotechnical evaluations and analyses may be necessary to check stability.

A geotechnical review was undertaken by Piteau in alignment with prefeasibility recommendation of the updated Life of Mine (LoM) pit design(ultimate pit) during the current feasibility study. The updated ultimate pit design incorporates the geotechnical design recommendations from Piteau (2022). The recommended 65° bench face angle (BFA) has been correctly applied to all 30 ft single-bench configurations, and the recommended 75° BFA (implemented through angled presplit blastholes) has been consistently applied to all 90 ft triple-bench configurations across the design sectors.

Measured inter-ramp slope heights (IRH) are generally consistent with those defined in the Piteau (2022) feasibility study. Exceptions occur in Design Sectors IX, X, XI, I, and II, where IRH values in the south, west, and north walls exceed previous designs (AHF_PH4_pit) by approximately 30 ft to 70 ft. The maximum IRH observed is 560 ft in the upper inter-ramp slopes of Design Sector IX (south wall).

These exceedances are considered geotechnically acceptable, as the kinematic assessment (Appendix D, Piteau 2022) identified no planar or wedge failure mechanisms that would impose a limiting inter-ramp height in these areas.

There were also localized deficiencies identified during this review in the various geotechnical sectors domains that are planned to be finetuned in the next stage of engineering mine design. The localized deficiencies are not expected to have any significant material or economic impact on the feasibility mine design or schedule.

Bench scaling should be carried out with the shovel bucket during bench excavation. Depending on bench performance, additional scaling may be required with scaling chain. Careful pull-back procedures should be carried out to minimize filling of subsequent benches with spilled material.

All slopes should be visually inspected at regular intervals for signs of distress and overall slope movement. Also, a slope displacement monitoring system consisting of survey prisms should be established during early stages of mining and maintained throughout the mine life and operation. Current practice is to measure prisms with automated systems such as robotic total stations (RTS) that include data acquisition and management tools for processing, interpretation, and reporting so that results can be evaluated regularly to assess slope behavior. This can also be supplemented with radar monitoring equipment (if needed) that can provide near real-time monitoring of slope deformations should the need arise. Both prism and radar monitoring provide advanced warning of possible large-scale instability and allow time for appropriate remedial measures to be implemented or mining plans to be modified, to accommodate the instability. Manual or automated wireline extensometers could be used to augment prism or radar monitoring in areas of observed surface deformation and cracking.

If slope movements are measured, monitoring (velocity) thresholds and trigger action response plans (TARPs) should be developed based on the observed slope performance and adjusted as required, to account for the effects of error and noise and to verify and maintain their effectiveness.

Other monitoring slope monitoring techniques such as inclinometers and time domain reflectometers (TDR) (for monitoring subsurface ground movements), or satellite-based surface surveying with global positioning systems (GPS) or InSAR (Interferometric Synthetic Aperture Radar) may need to be incorporated into the slope monitoring system if the need arises.

Regular inspection of the crest and exposed benches on the mine plan should be carried out to identify any signs of tension cracking, increased raveling/rockfall, or other signs of instability. The locations of observed tension cracks should be surveyed and added to geotechnical plans to allow assessment of slope deformation with respect to slope monitoring data and any potential mechanism(s) of instability. Any unusual signs of slope raveling or distress should be communicated to the Mine Geotechnical Team and assessed accordingly.

Systematic documentation of bench performance (achieved BFA) and structural mapping (by manual or photogrammetric methods) is recommended to be carried out while mining the Copper King pit. If ongoing bench or slope performance is unfavorable and/or structural mapping indicates adverse conditions as new geology is exposed, local revisions to the mine plan may be required.

Documentation of the as-built bench performance of mined slopes is recommended using reliable methods such as photogrammetry models, high-resolution laser scan digital terrain models (DTM), or manual bench documentation mapping. This information can be used to calibrate breakback angles calculated from the kinematic CFA assessments and support potential optimization of the IRAs during mining.

In addition, rockfall field testing and modeling is recommended to calibrate rockfall model input parameters and develop a “site-specific” design catch berm width for rockfall protection instead of the Modified Richie Criteria (Equation 3) which was adopted for this study. Such rockfall calibration could also support potential optimization of the IRAs.

It is recommended that future drilling in bedrock should include geotechnical logging of all parameters comprising RMR (according to Bieniawski, 1976) and consistent PLI testing as described in Section 2.5 in the final (Piteau) report. This geomechanical information should be incorporated into the current geomechanical and rock strength databases developed for the feasibility study and would support future geotechnical evaluations of the CK Gold Project.

Deep-seated stability analysis of the slopes indicated that the east and southeast walls (Design Sectors V and VI near Section E1 and Design Sectors VI and VII near Section SE1) require slope depressurization to meet the design acceptance criteria of a minimum FOS of 1.20 for overall, interramp, and compound slopes. Depressurization targets at these two sections are defined in terms of Hu and are based on the EOM groundwater surface provided by NEIRBO. To achieve acceptable stability, it is required that pore pressures in the east wall slopes (Section E1, west of the Copper King fault) be reduced to levels equivalent to a 1.0 Hu (hydrostatic conditions) (from a 1.4 Hu defined by NEIRBO). In the southeast slope (Section SE1, north of N 234,025) it is required that pore pressures be reduced to levels equivalent to a 1.2 Hu (from a 1.4 Hu). Both Hu targets are for the lower slopes and assume that a 0.8 Hu will be present in the MS-MV unit in the upper slope east of the Copper King fault (at Section E1) and that a 1.0 Hu will be present in the granodiorite rock mass in the upper slope south of N 234,025 (at Section SE1).

Based on these Hu targets, it is recommended that additional 3D hydrogeological modeling be performed that includes simulation of active depressurization measures (such as pumping wells and/or horizontal or inclined drains) in the east and southeast slopes to determine what measures are needed to achieve the depressurization targets. This hydrogeological modeling should also incorporate a mine plan that uses the feasibility slope design recommendations and that has been checked by Piteau for conformance to the design. After hydrogeological modeling of active depressurization is complete, it is recommended that the calculated pore pressures be provided to Piteau (for example, as a “grid” defined by x, y, z coordinates and pore pressure, u) to perform new 2D anisotropic stability analyses of the east and southeast slopes to check if the depressurization targets have been achieved and confirm that the FOS of the overall, interramp, and compound slopes meet the 1.20 design acceptance criteria.

Stability of the east and southeast slopes is dependent on achieving specific depressurization targets and these areas will likely require some form of active depressurization (i.e., pumping wells and/or drains) which can be defined through additional hydrogeological modeling as described in the Piteau report. As integral part of active depressurization, it is also recommended that hydrogeological monitoring (such as multi-level vibrating-wire piezometers or VWPs) be installed to monitor pore pressures and verify that the required targets in the critical areas of the slope are being achieved in advance of mining and during the LoM.

To assist in achieving and maintaining depressurization targets as well as avoid development of erosional gullies and slope instabilities within the mine plan, the following surface water controls are recommended:

The mine plan has only one main haul road providing access to the pit. Single haul road access could pose potential risks to the mining sequence and ore delivery if instabilities develop above or below the haul roads. Ongoing slope monitoring and visual stability inspections should be carried out to prevent the loss of this single main access point into and out of the mine plan.

A hydrogeology investigation for the Project was conducted by NEIRBO. NEIRBO issued a technical report in December 2023 titled “Hydrogeological Characterization and Groundwater Flow Model.” This section contains a summary of the report.

The Project is located in the Silver Crown mining district of southeast Wyoming, approximately 20 miles west of the city of Cheyenne. The property comprises approximately 1,120 acres (2 square miles) on the southeastern margin of the Laramie Mountains. The Project is fully-owned by U.S. Gold. The Project facilities include an open pit, tailings management facility, two waste rock facilities, plant site, and an ore stockpile area.

The highest elevation in the open-pit area is about 7,100 ft and the pit will be excavated to 6,120 ft. The mine plan has eight years of mining and passive dewatering as the open pit is advanced. The post-mining phase includes pit backfilling with tailings and waste rock. The first two years after mining ends will be dedicated to site reclamation.

The orebody is hosted in granitic rocks that have limited permeability and limited water-storage capacity. Groundwater wells completed in the granite rocks have typically yielded 0 gpm to 5 gpm. The Project has completed an extensive hydrogeological site characterization to support development of a regional groundwater flow model (Flow Model). Aquifer testing has included pumping tests and discrete depth-interval packer testing. Hydraulic conductivity and specific storage properties were estimated from these tests. Groundwater levels and pore pressures were obtained from wells and Vibrating Wire Piezometers.

A calibrated Flow Model was developed to represent the hydrogeological system. The Flow Model simulates pre-mining conditions and hydrological changes during the mining and post-mining phases. The Flow Model predicts groundwater system changes due to passive pit dewatering, natural recharge changes due to facility construction, and pit backfill during the post-mining phase.

Predictions during the mining and post-mining periods included groundwater-level, pit inflow, streamflow, and evapotranspiration changes. Predicted mine-induced drawdown was greatest near the pit and it decreased rapidly away from the pit. Predicted drawdown was 10 ft or less outside the Operating Permit Boundary at the end of mining. After 150-years, the discernable predicted drawdown extended 180 ft outside the Permit operating boundary in a small area shown on Figure 13.3. The nearest domestic wells were 2,000 ft from the predicted 10-feet drawdown area. At this distance, any mine induced drawdown would likely not be discernable from natural variation and groundwater-level changes induced by the domestic wells themselves.

The Middle Fork of Crow Creek is the nearest stream, and its flow was predicted to decrease 0.02 cubic feet per second ten years after mine-ending. The other stream segments had zero to 0.01 cubic feet per second changes in flow.

Average annual groundwater pit inflow was expected to be less than 15 gpm. This low pit inflow would be manageable using passive, in-pit sumps. Dewatering wells are not expected to be necessary. Cumulative pit inflows during mining were predicted to be 130 acre-feet.

After mining ends, the pit will be backfilled with tailings and waste rock. Groundwater and precipitation will flow into the backfill material and water levels will slowly rise until they stabilize at 6,717 ft after about 130 years. A pit lake is not expected to form since evaporation losses will keep the groundwater level below the top of backfill. This will result in the pit being a hydraulic sink with no groundwater outflows.

Quarterly background groundwater quality data have been obtained in seven project area wells from 2020 Quarter 4 to 2022 Quarter 1. The background water samples indicate the water quality is generally below regulatory standard concentrations. However, a few constituents in select wells have exceeded the standards for domestic, agriculture, and livestock uses. The domestic water-quality standard for fluoride and pH was consistently exceeded in four of the seven wells. Each well has exceeded standards for iron, manganese, mercury, adjusted gross alpha, or sodium adsorption ratio on at least one occasion. Well MW-7, in the middle of the proposed pit, has consistently exceeded the standard for uranium and gross alpha. The adjusted gross alpha standard was exceeded in three of the six samples in MW-7.

Figure 13.3, Figure 13.4 and Figure 13.5 show the predicted drawdown at the end of mining and 150 years post mining, groundwater monitoring locations and predicted open pit groundwater inflows, respectively.

Figure 13.3: Predicted Drawdown at the End of Mining and Post-Mining Year 150

Source: NEIRBO Hydro Geology, 2023.