Business Context and Reporting Period
I-80 Gold Corp. filed a Form 8-K dated September 21, 2026, under Item 8.01 to report an updated SEC Technical Report Summary and Pre-Feasibility Study (PFS) for the Granite Creek Underground Project in Humboldt County, Nevada. The PFS is dated September 21, 2026, with an effective date of March 31, 2026, and was prepared under SEC S-K 1300 by independent qualified persons and a company employee.
Granite Creek Underground is a fully permitted, constructed and operating mine ramping toward commercial production, which is expected in late 2026. The project is currently producing approximately 540 tonnes per day, with a planned full-production rate of approximately 900 tonnes per day. The PFS assumes third-party toll milling through mid-2027 and processing at the company’s refurbished Lone Tree Plant beginning in late 2027.
Key Financial and Operating Metrics
| Metric | PFS Estimate |
|---|---|
| Assumed gold price | $2,750 per ounce |
| Pre-tax NPV at 5% | $138 million |
| After-tax NPV at 5% | $118 million |
| After-tax cash flow | $153 million |
| Headline mine life | Approximately 8.5 years |
| Total ore processed | 2.198 million tonnes at 7.87 g/t gold |
| Total gold recovered | 485,000 ounces |
| Average annual production, 2028–2032 | 75,100 ounces |
| Average annual life-of-mine production | 53,900 ounces |
| Life-of-mine cash costs | $2,076 per ounce |
| 2028–2032 cash costs | $1,827 per ounce |
| Life-of-mine AISC, excluding Lone Tree refurbishment allocation | $2,273 per ounce |
| 2028–2032 AISC, excluding Lone Tree refurbishment allocation | $1,915 per ounce |
| Total capital and closure costs | $144.9 million |
The detailed cash-flow model estimates life-of-mine revenue of $1.331 billion, operating cash flow of $298 million and net cash flow of $153 million. The model estimates 2026 recovered production of approximately 35,700 ounces and net cash flow of negative $33 million, followed by negative net cash flow of $42 million in 2027. The filing separately states that 2026 recovered production is expected to range from 30,000 to 40,000 ounces.
Capital costs comprise $82.9 million of sustaining capital, $49.3 million allocated to Lone Tree autoclave refurbishment and $12.7 million of closure and reclamation costs. The filing does not provide company-level debt, cash balances, liquidity, or financing commitments.
Mineral Reserves and Resources
- Proven and probable underground reserves total 2.198 million tonnes at 7.87 g/t gold, containing approximately 556,500 ounces.
- Measured and indicated underground resources total approximately 1.810 million tonnes at 5.38 g/t gold, containing approximately 313,300 ounces; inferred resources total approximately 871,000 tonnes at 7.04 g/t, containing approximately 197,000 ounces.
- The updated open-pit measured and indicated resource totals approximately 49.4 million attributable tonnes at 0.97 g/t, containing approximately 1.528 million ounces. The open-pit resource is not included in the underground PFS mine plan.
Material Changes Versus the Prior Comparable Study
- The March 2025 Granite Creek PEA has been superseded by the 2026 underground PFS.
- The updated underground resource incorporates approximately 36,470 metres of drilling from 164 core holes completed from 2023 through the end of 2025.
- Step-out drilling expanded the mineralized envelope, while infill drilling increased resource confidence and supported conversion of a majority of the resource to reserves.
- The PFS applies more conservative grade-shell assumptions than the prior PEA, resulting in lower grades intended to better reflect current mining performance.
- The processing strategy changed to assume third-party toll milling through mid-2027, followed by Lone Tree Plant processing after planned refurbishment and commissioning in late 2027. The change is expected to reduce processing costs and increase production and cash flow beginning in 2028.
- The filing reports a larger optimized open-pit resource following an increase in the assumed gold price, but the open-pit project remains subject to separate technical studies and permitting.
Guidance, Outlook, Commentary and Risks
- Commercial production is expected in late 2026, with steady-state production targeted at approximately 75,000 ounces annually during 2028–2032.
- The company expects the Lone Tree autoclave and carbon-in-leach plant to be commissioned in late 2027, subject to successful refurbishment and commissioning.
- The 2026 exploration program includes infill and step-out drilling at the South Pacific, Rangefront, Otto and Ogee zones. The CX Zone is being evaluated as a potential underground target in a planned multi-year drill program beginning in 2027.
- Water inflows have stabilized but are managed by a pumping system operating near capacity. Additional sumps, higher-capacity pumps and dewatering wells are planned; residual passive inflows are estimated at 2,500–2,700 gallons per minute until additional wells advance below current workings.
- A second water treatment plant is undergoing commissioning and is expected to increase surface treatment capacity by approximately 3,500 gallons per minute.
- Key risks include gold-price volatility, higher capital and operating costs, financing availability, successful Lone Tree refurbishment, processing capacity, metallurgical recovery, mining and dewatering conditions, permitting and environmental compliance, labor and equipment availability, geological uncertainty, resource-to-reserve conversion and reclamation obligations.
- Cash cost and AISC figures are non-GAAP measures and may not be comparable with similarly titled measures reported by other issuers.
Important Facts for Investors to Verify
- Confirm the timing, scope, cost and financing of the $49.3 million Lone Tree refurbishment and the expected late-2027 commissioning.
- Reconcile the headline 8.5-year mine life with the appendix cash-flow model, which presents an 8.3-year life-of-mine period.
- Assess whether the assumed $2,750-per-ounce gold price adequately supports the reported $118 million after-tax NPV and the $2,273-per-ounce life-of-mine AISC excluding refurbishment capital.
- Verify actual 2026 production against the 30,000–40,000-ounce expectation and monitor progress toward the 900-tonnes-per-day mining rate.
- Review water-management performance, pumping capacity, treatment-plant commissioning and related environmental requirements.
- Distinguish underground reserves included in the PFS from open-pit and inferred resources, which are not demonstrated to be economically viable or included in the current mine plan.
- Confirm the company’s available cash, debt, liquidity and funding requirements, which are not disclosed in this 8-K.