enCore Energy’s 100% owned Gas Hills Project is one of the Company’s development priorities following the focus on operations in South Texas. The Gas Hills Uranium Project consists of approximately 1,280 surface acres and 12,960 net mineral acres of unpatented lode mining claims, a State of Wyoming mineral lease, and private mineral leases, within a brownfield site which has experienced extensive development including mine and mill site production.
enCore views its Gas Hills Project as an advanced ISR project which has established scale and grade of ISR amenable uranium resources that have the potential to be highly competitive. The Company has begun the permit process for ISR operation and is continuing analysis of the project.
Between 1953 and 1988, many companies explored, developed, and produced uranium in the Gas Hills Uranium District, situated 45 miles east of Riverton, Wyoming. Three uranium mills operated in the District, and two other nearby mills were also fed by ore mined from the Gas Hills. Historical cumulative production from the District exceeded 100 million pounds of U3O8, mainly from open pit, but also from underground and ISR mining operations. An adjacent project has undertaken sufficient testing for ISR of uranium deposits on their property, received all permits and licenses to operate, and in 2014 received authorization for the company to proceed with development of their project using ISR technology. Startup of the ISR project was deferred because of a downturn in the uranium market price at the time.
S-K 1300 Estimated Mineral Resources
In February of 2025, the Company filed an SK 1300 Technical Report independent Technical Report and preliminary PEA for the Gas Hills Uranium Project prepared by WWC Engineering (the “Gas Hills Reports”) with an effective date of December 31, 2024. Importantly, an ISR resource estimate was established and supported by numerous hydrology studies confirming that the resources located below the water table are ideally suited for ISR mining techniques.
Data sources for the estimation of uranium mineral resources for the Gas Hills Project include radiometric equivalent data (e U3O8) for 4,570 drill holes, and e U3O8 and Prompt Fission Neutron (“PFN”) logging data for 272 drill holes. The intent of recent drilling between 2007 and 2024 included verification of earlier data for drill holes and other exploration results.
The current Gas Hills Reports indicate a pre-tax NPV of $166.9 million at an 8% discount rate with an IRR of 54.8 % compared to an after-tax NPV of $141.8 million at an 8% discount rate with an IRR of 50.2%. The NPV assumes cash flows take place in the middle of each period. The NPV and IRR calculations are based on Year-2 through Year-11 and includes costs escalated by 8% per year from Year-4 and Year-3 treated as if the escalated costs occurred in Year-2. This approach to calculating the NPV was taken because Year-2 is the first year that a significant sum of capital is invested into the Project.
The mine plan and economic analysis are based on the following assumptions:
- A recovery factor of 80% of the measured and indicated mineral resource (no inferred mineral resource is included)
- A U3O8 sales price of $87.00/lb.
- A mine life of 11 years
- A pre-income tax cost including royalties, state and local taxes, operating costs, and capital costs of $40.61/lb.
- Initial capital costs of $55.2 million
Costs for the Gas Hills Project are based on economic analyses for similar ISR uranium projects in the Wyoming region as well as the author of the Gas Hills Reports in-house experience with mining and construction costs. To date, no detailed design work has been completed for the wellfields or the CPP. The authors of the Gas Hills Reports believe that general industry costs from similar projects adequately provide a ± 30% cost accuracy which is in accordance with industry standards for a PEA and complies with item 1302 of Regulation S-K for an Initial Assessment with economics.
The uranium mineralization is contained in roll-front deposits hosted by arkosic sandstone beds of the Eocene Wind River Formation. Based on areas of wide-spaced limited historical drilling and areas of past mine production, the Company believes that there is sufficient geological evidence to interpret that mineralization may extend from current mineral resource areas along identified trends. The Company is now focused on commencing the permitting process and growing the ISR-amenable resources at the Gas Hills Project.
The Project consists of four resource areas that contain ISR amenable resources named by enCore as the West Unit, Central Unit, South Black Mountain, and Jeep. There is an additional non-ISR amenable resource area at the Gas Hills Project named the Rock Hill Unit as well as other shallow areas with resources located above the water table that were not considered in the economic assessment portion of the Gas Hills Reports. For the purposes of the Gas Hills Reports, uranium recovery was estimated at 6,164,000 lbs at an extraction rate of 1.0 million pounds U3O8 per year with a long-term uranium price of USD $87.00/lb using a low pH lixiviant.
Frequently Asked Questions
Uranium is already in the underground aquifer, which is why the Environmental Protection Agency has deemed it contaminated and not suitable for drinking water for humans or animals. This groundwater flows through sediments mineralized with uranium. enCore will be removing much of this contaminate. Commercial scale In-Situ Recovery (ISR) uranium extraction has operated in the US for almost 50 years, replacing conventional mining when conditions are appropriate. In these 50 years, no groundwater that has been designated as drinking water quality has been left in a contaminated state after final closure of the uranium extraction operations. Historically, following completion of uranium recovery, these operations have restored the underground aquifer to the same Federal use category it had before extraction began.
The United States Environmental Protection Agency (EPA) reviews every new ISR operation and only authorizes ISR operations in a very specific portion of underground aquifers, which the EPA classifies as contaminated for drinking purposes. Absolutely no activities are allowed outside of this small, designated area. United States Nuclear Regulation Committee (NRC) and State regulations require the company to return the water quality within this area to the same water quality use standards for which it was previously designated. Unlike most water wells, ISR operation wells are cased in heavy duty PVC piping, and once mining operations are complete, are filled with cement, to prevent fluid from entering any other water source or ground interval. During mining operations, groundwater is monitored with electronic and staffed controls as required by regulatory agencies which review the data monthly or quarterly. Any exception must be reported by the operator to these agencies immediately and corrective action immediately implemented.
This is not the cold war era of the 1950s and 1960s when environmental cleanup and employee safety at conventional uranium mines were afterthoughts. Licensing of Gas Hills ISR projects requires firm plans for not only development and operations, but also for total reclamation and restoration of both the site and the affected groundwater. enCore will be required to secure and post a total of approximately $15 million in bonds with the Environmental Protection Agency and Nuclear Regulatory Commission (NRC) to ensure sound reclamation. Only when the cleanup is approved, by both the State of Wyoming and the NRC, will the bonds be returned to enCore.
The Nuclear energy industry is the singularly most highly regulated industry in the United States which includes everything from uranium mining to the x-ray in the local hospital. There are no exceptions.
No, enCore does not use harsh chemicals in the uranium extraction process and we only extract uranium from the part of the aquifer designated by the Environmental Protection Agency as contaminated and that cannot be used for drinking water by humans or animals. We will use only gaseous oxygen and a bicarbonate. This is the equivalent of adding oxygen and baking soda to the contaminated underground aquifer, never touching drinking water. In the contaminated aquifer, the gaseous oxygen and bicarbonate within with water disolves the uranium minerals which exist as coatings on sand grains. We recover this groundwater, along with the dissolved uranium minerals, to our water treatment plant (similar to a home water softener only much larger) where the uranium is removed. Once the uranium is removed, the remaining water is then recycled and returned to the aquifer. Unlike conventional uranium mills, we do not use any acid to dissolve the uranium as they do in foreign countries. The United States has very high environmental standards.
There are 24 reclaimed uranium ISR projects in the United States, with enCore Directors having worked on 10 of these projects. enCore leadership co-invented ISR and has worked in the field for over 40 years building, operating and reclaiming in-situ recovery uranium projects in both Texas and Wyoming.
It is also important to understand that, typically, the reclamation of ISR projects is a continual yet finite process. As enCore works to extract uranium, it builds wellfields in specific patterns and then moves along the uranium resources over time as extraction proceeds. The Company then removes (from production) and reclaims exhausted wellfields as it completes the ongoing extraction process, thereby moving from one area to the next.
The nuclear energy industry is extremely regulated with safety and health regulations in place (including worker safety, air quality, radiation, water quality, spill management and more) that apply not only to on-site facilities but also extend to the transportation of the natural uranium product (yellowcake). Yellowcake is a dry powder. It is sealed in steel containers for transport to a conversion facility where it is transformed into an energy source for domestic and commercial use in the electric grid. It is shipped by tractor-trailer and regulated by the US Department of Transportation with extremely stringent requirements. Yellowcake shipments require advance written notification to the Nuclear Regulatory Commission (NRC) of the planned shipment including the content, quantity, and route to be followed. In addition, only a small number of trucking companies are certified to handle and transport yellowcake.
enCore is a North American company and all benefits stay within the United States. All uranium produced in Gas Hills will be sold only to domestic US power companies who use uranium to generate electricity which powers your home and business.
It is expected that activity from development, operations and reclamation will last approximately 20 years and will fuel our economy while creating jobs and strengthen local businesses. It is important to enCore that we provide opportunities for our youth to benefit from the extraction activities through jobs, education and training, thereby allowing our communities and families to grow and prosper.
During uranium extraction operations, large quantities of water from the contaminated underground aquifer circulate through the aquifer to dissolve uranium in the water. The uranium is then recovered in a water treatment plant and the water is reinjected into the ground. Consumptive use of ground water is limited to approximately 1% of the circulated water which typically averages between 50 to 100 gallons per minute. Once extraction is complete, the recirculated water is cleaned, 99% returned to the aquifer and again suitable for all the same uses that it was prior to enCore’s involvement. It is important that enCore conserve and recycle water, and it is vital to the operations to maintain constant water levels for successful extraction of the uranium. It is imperative that we conduct ourselves as good corporate citizens and contribute in a positive way to the communities in which we work. We must leave a positive legacy which includes valuable infrastructure, water wells, power lines, clean drinking water and vibrant communities with high paying jobs and transferable skills for our youth.
In-situ recovery is not fracking. Fracking utilizes a totally different process than ISR. Fracking opens up preferential “fractures” in the subsurface using extreme pressure in order to provide conduits to extract hydrocarbons. Fracking is not a viable practice for ISR. ISR is designed specifically to avoid opening “cracks” and works by flowing water through existing sediments within an aquifer. Uranium minerals suitable for ISR extraction are deposited as coatings on sand grains and spread across both vertical and horizontal areas of the contaminated underground aquifer. ISR wells are designed to ensure that the water used in injection and extraction flows slowly and consistently through the aquifer in order to contact and dissolve the uranium minerals.
Prior to any extraction activity, enCore is required by law to install a series of water wells within the proposed extraction area – in the contaminated aquifer and within any adjacent aquifers. The water quality in each of these wells is tested by an independent 3rd party (a licensed laboratory) which establishes the baseline water quality and use category of these groundwaters prior to extraction. This establishes the use category enCore will be required meet in reclamation. Pre-extraction levels are established by independent experts, and in reclamation, these independent experts will also verify that pre-extraction level are returned to the aquifer.