Large scale hydrogeological testing is now underway at Mine Unit 1 following AMU’s recent 9.96Mlb resource update, supporting permitting activities and the Company’s targeted Q4 2026 Scoping Study.
American Uranium Limited (ASX:AMU, OTC:AMUIF) (American Uranium, AMU or the Company) is pleased to advise that large-scale hydrogeological pump testing has commenced at proposed Mine Unit 1 of its Lo Herma ISR Uranium Project in Wyoming’s Powder River Basin. The program represents another important milestone in advancing Lo Herma from resource definition toward project evaluation, permitting and potential ISR development.
Highlights
- Major development milestone: Large-scale aquifer testing has commenced at Lo Herma Mine Unit 1, marking an important step toward ISR project evaluation and development.
- Key hydrogeological data being collected: Testing is designed to further assess groundwater flow, hydraulic connectivity and wellfield development parameters across the proposed initial mining area.
- Follows recent 9.96Mlb resource update: The program follows AMU’s August 2026 resource update, including 7.38Mlbs U3O8 within the proposed Scoping Study area.
- Supporting next major catalyst: Results are expected to provide important inputs to the Company’s targeted Q4 2026 Scoping Study.
Aquifer pump testing follows the Company’s 16 July 2026 announcement that seven additional hydrogeological monitoring wells had been installed at Mine Unit 1. The program is centred on the existing LH MW-003 pumping well and incorporates monitoring wells in the target production horizon, overlying units and an underlying sand interval.
The program is designed to generate key hydrogeological data for groundwater modelling, permitting activities and future ISR wellfield design. It will assess groundwater flow through the target production sands, hydraulic connectivity between relevant units and wellfield development parameters across the proposed initial mining area. Results from the program are expected to support groundwater modelling inputs required for permitting activities and provide key parameters for the planned Scoping Study.
The program follows AMU’s 4 August 2026 Lo Herma Mineral Resource Estimate update, which reported total Lo Herma resources of 9.96Mlbs U3O8, including 4.79Mlbs Indicated. Within the proposed Scoping Study footprint across Mine Units 1, 2 and 3, resources increased to 7.38Mlbs U3O8, with 54% classified as Indicated. The combination of the updated resource and commencement of large-scale pump testing continues to strengthen the technical foundation for Lo Herma’s planned Scoping Study and longer-term development pathway. The Company expects results from the testing program to be incorporated into the targeted Q4 2026 Scoping Study.
AMU CEO and Executive Director Bruce Lane commented: “With our updated 9.96Mlb resource completed and pump testing now underway, Lo Herma continues to advance toward development. The program will deliver key data for groundwater modelling, permitting and ISR wellfield design.
Pump testing is another important milestone as we progress toward our targeted Q4 2026 Scoping Study. Mine Unit 1 is our most advanced proposed mine unit and is currently expected to form the initial stage of development evaluated in that study.”
Previous Testing Demonstrated Favourable Hydrogeological Conditions
The current program builds on AMU’s 2025 hydrogeological testing, undertaken by Petrotek Corporation, which included step drawdown and sustained pumping tests on four previously installed monitoring wells. As previously advised on 20 January 2026, those tests demonstrated sustained flow rates and minimal aquifer drawdown, with Petrotek concluding that hydrogeological characteristics were consistent with other permitted and operating ISR uranium projects in Wyoming’s southern Powder River Basin. The current large-scale program is designed to evaluate whether those favourable hydrogeological characteristics are present across a broader portion of the proposed Mine Unit 1 development area and to provide additional data required for groundwater modelling, permitting and future wellfield design.
Mine Unit 1 Large-Scale Aquifer Testing Now Underway
The program is based on a large-scale pump test layout prepared by Petrotek Corporation (Figure 3). It is centred on LH-MW-003, completed in the Middle C Sand, with observation wells positioned in the target production horizon, overlying units and an underlying sand interval. The test configuration reflects the next phase of hydrogeological work recommended by Petrotek following its 2025 assessment.
Four Middle C Sand observation wells are located approximately 400-500 feet from the pumping well to evaluate directional transmissivity. Additional wells in the A Coal, D Sand and underlying sand are designed to monitor whether pumping in the Middle C Sand produces responses in adjacent units.
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