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enCore Energy Encounters Highest Grade Drill Results at Alta Mesa Uranium Project; Provides Status on South Texas Production Operations

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enCore Energy Encounters Highest Grade Drill Results at Alta Mesa Uranium Project; Provides Status on South Texas Production Operations






enCore Energy Corp. (NASDAQ: EU) (TSX-V: EU) a domestic uranium producer, today announced the highest grade drill results to date since drilling activities restarted from the Alta Mesa Project in South Texas. These results significantly exceed the cutoff grade thickness requirements for In-Situ Recovery of uranium. The Company also reports that work to advance the Alta Mesa Uranium Central Processing Plant and Wellfield towards production is advancing on schedule.


Highlights include:

  • Drilling from Alta Mesa’s Production Area Authorization provides results that range up to a grade thickness of 8.4 with a maximum thickness of 13.5 feet. The cutoff grade thickness for ISR in South Texas is generally accepted to be 0.3 with grade thickness being the relevant factor in determining reasonable prospects for economic extraction;
  • The Alta Mesa ISR Uranium Central Processing Plant upgrades and refurbishments are advancing on schedule for the planned early 2024 resumption of uranium production;
  • Initial production from Alta Mesa’s PAA-7 wellfield will have a total of 59 production wells with 36 extraction wells and 23 injection wells that form the startup production patterns.  57 of these are completed with the last two wells scheduled for completion over the next few days.  The wells are being prepared for connection to the pipeline to the CPP;
  • Production from the wellfield at Alta Mesa will be increasing as additional production patterns are completed following the initial 59 wells and duplicate the process used for the initial Alta Mesa startup in 2005. Drilling and well installation for the follow-on production patterns is already well underway and will continue as CPP capacity is reached; and
  • As previously reported, uranium production from the Rosita Uranium CPP, which commenced in November 2023 and has completed its first shipment of uranium, continues to maintain expected production levels.


Paul Goranson, enCore Energy’s Chief Executive Officer, stated: “We are extremely pleased with the drilling results from Alta Mesa. Cutoff grade thickness for ISR operations in Texas are generally 0.3 GT for economic extraction. With drilling returning a significant number of GTs in production delineation holes in excess of 3.0 with a high of 8.4, we are becoming increasingly optimistic that our contained uranium will exceed estimates contained in the 2023 technical report that cited GTs averaging 0.59 to 0.68 for each of the specific ore horizons. Indeed, we are confirming higher grade portions of the mineralized zone than initially estimated from broader spaced drilling as proposed in the 2023 technical report. Having directed the initial development and operation of Alta Mesa for a private company in 2005, I have observed that this project has historically consistently exceeded expectations. We look forward to returning Alta Mesa to production in the coming weeks.”


Wellfield delineation drilling commenced in the spring of 2023 at the Alta Mesa Project PAA-7 along a previously defined ore body consisting of stacked roll fronts. The NI 43-101 Technical Report dated January 19, 2023, and titled “Technical Report Summary for the Alta Mesa Uranium Project, Brooks and Jim Hogg Counties, Texas, USA” stated that PAA-7 contains 1.292 million pounds U3O8 indicated resources and 0.175 million pounds U3O8 inferred resources with an average grade thickness (GT is defined as grade multiplied by intercept thickness) ranging from 0.59 to 0.68 GT using a 0.3 GT cutoff. As has been observed from historic drilling at Alta Mesa, the density of drilling necessary to install an ISR wellfield provides the opportunity to identify higher grade portions of the ore body than initially estimated with broader spaced drilling programs. The table of drilling results below confirm that observation, and the results exceed the historical observations for PAA-7, to date. As drilling continues during additional wellfield development in PAA-7, we expect that we will continue to observe results that could lead to an average GT for the area significantly higher than the average GT reported in the technical report.


To view the Alta Mesa CPP and Wellfield and Rosita CPP maps please visit:


Alta Mesa Uranium Central Processing Plant Development Update


At the Alta Mesa Uranium CPP, enCore has met most of the key objectives for the refurbishment of the processing circuits necessary for the planned early 2024 restart. Work remaining includes final inspection of the ion exchange (“IX”) columns, testing the precipitation tanks, completing tie-in of the scrubber system, and installation and testing of the process circuit instrumentation. The yellowcake drying circuit upgrades are advancing with the filter press support infrastructure and yellowcake storage hoppers on site.  Refurbishment and testing of the yellowcake drying system is progressing with that work scheduled to be completed just prior to the anticipated production restart timelines. The bulk chemical systems for the IX elution process have been installed and tested. The electrical systems including transformers and motor control centers have been completed.


Within PAA-7, enCore is installing injection and production wells in the wellfield and has completed installation of the electrical transmission lines necessary for initial start-up and the pipelines to connect the wellfield to the Alta Mesa CPP. All necessary equipment for the start-up of production in the PAA-7 wellfield has been received or has been ordered with a confirmed delivery schedule. Wellfield construction activities are well advanced with 100% of well manifold, electrical, and oxygen distribution systems at the wellfield modules are completed. The pipeline booster pump stations are scheduled for installation by the end of March 2024.


Alta Mesa Wellfield Drilling Update


The wellfield drilling operations , which commenced in March 2023, are advancing rapidly with 126 holes drilled since the previous update (January 17, 2024). In total, 571 drill holes have been completed through March 8th, 2024. There are currently six (6) drill rigs in full operation at Alta Mesa, with contracts anticipated for additional rigs expected at site by the end of March 2024.


Further refined delineation drilling within the PAA-7 continues to establish the exact pattern of injection and recovery wells from which to maximize production efficiency as additional patterns are prepared for ramped up production. Over 140 holes have been cased or are scheduled to be cased with an additional 75 holes under review by geological staff for possible casing.


Significant Alta Mesa Wellfield Drilling Results


Drill Hole Goliad Sandstone Horizon Depth
Grade %
Hole GT
172-95 LCL-1 515.5 0.275 3.5 0.967
171-97 LCU-1 489.0 0.281 2.0 0.562
181-93 LCL-2 521.0 0.174 2.5 0.434
172-96 LCU-2 505.0 0.196 5.5 1.077
181-91 LCL-1 518.0 0.667 4.5 3.041
172-96 LCU-1 488.5 0.101 3.5 0.353
182-96 LCU-2 510.0 0.594 5.5 3.266
185-113 LCU-2 504.0 0.311 13.5 4.197
184-112 LCU-2 505.5 0.340 10.5 3.567
184-112 LCL-1 522.0 0.267 7.0 1.869
181-93 LCL-1 515.0 0.512 10.0 5.118
181-91 LCL-1 513.0 0.760 11.0 8.356
181-92 LCL-1 511.5 0.368 3.5 1.287
170-102 LCU-2 496.0 0.171 6.5 1.113
184-96 LCU-2 511.0 0.263 3.5 0.920
170-104 LCU-1 490.5 0.250 4.0 1.002
170-105 LCU-2 500.0 0.113 4.5 0.508
171-98 LCL-1 503.5 0.291 7.0 2.038
185-112 LCL-2 527.5 0.660 4.0 2.64
181-90 LCU-1 496.0 0.265 7.0 1.853
183-96 LCL-1 521.0 0.426 5.0 2.130
172-96 LCL-1 512.0 0.169 2.0 0.338
185-113 LCU-1 502.0 0.465 12.0 5.579
170-100 LCL-1 511.5 0.147 2.5 0.368
181-92 LCL-1 513.5 0.660 9.0 5.935
172-94 LCL-1 519.5 0.093 3.5 0.326
183-96 LCU-2 504.5 0.135 10.5 1.417
LCL-2 530.0 0.192 5.0 0.961 2.378
185-112 LCU-2 503.5 0.140 2.5 0.350
174-95 LCL-1 524.5 0.106 4.5 0.479
180-92 LCU-1 495.0 0.251 7.5 1.884
All intercepts are located in the PAA-7 which hosts mineralization within the Goliad Formation.  The
Company has identified five saturated (required for ISR), mineralized sandstone horizons within the Goliad
Formation lying approximately 400 to 535 feet below the surface.  The water level is located approximately
120 feet below the surface. Grade Thickness is Grade % U3O8 multiplied by the thickness of the
mineralization. ISR recoverable uranium with a Grade Thickness of >0.3 is considered suitable for inclusion
in a wellfield.


Alta Mesa In-Situ Recovery Uranium Central Processing Plant & Wellfield


The Alta Mesa CPP and Wellfield hosts a fully licensed and constructed ISR uranium plant, located on 200,000+ acres of private land in the state of Texas. Alta Mesa will be enCore’s second producing location. On February 23, 2024, the Company concluded the sale of a 30% interest in the Alta Mesa Project to Boss Energy Limited (ASX:BOE; OTCQX:BQSSF), a leading Australian emerging ISR uranium producer, to form a joint venture (“JV”) managed by enCore. Consideration received was $60 million USD plus an additional $10 million USD as a placement into enCore’s shares. The proceeds from this sale will enable enCore to accelerate its production timelines across its entire pipeline of production targeted assets.


Total operating capacity at the Alta Mesa CPP is 1.5 million lbs. U3O8 (uranium) per year with an additional drying capacity of more than 0.5 million lbs. U3O8. The Alta Mesa CPP historically produced nearly 5 million lbs. U3O8 between 2005 and 2013, when full production was curtailed as a result of low uranium prices.


Alta Mesa CPP and Wellfield highlights:

  • The Alta Mesa CPP is enCore’s third fully licensed production facility, along with the Rosita CPP and Kingsville Dome CPP, all located in the business-friendly state of Texas. There are only eleven (11) licensed and constructed uranium production facilities in all of the United States (US).
  • Alta Mesa CPP’s operations are located on private land, with 100% of minerals privately owned, and in a supportive jurisdiction with primary regulatory authority residing with the State of Texas.
  • The Alta Mesa CPP utilizes well-known ISR technology to extract uranium in a non-invasive process using natural groundwater and oxygen, coupled with a proven ion exchange process, to recover the uranium.


Alta Mesa & Mesteña Grande Mineral
Resource Summary (0.30 GT cutoff)1,2


Avg. Grade

(% U3O8)



Total Measured Mineral Resource1 54,000 0.152 164,000
Alta Mesa Indicated Mineral Resource 1,397,000 0.106 2,959,000
Mesteña Grande Indicated Mineral Resource 119,000 0.120 287,000
Total Measured & Indicated Resources 1,570,000 0.109 3,410,000
Alta Mesa Inferred Mineral Resource 1,263,000 0.126 3,192,000
Mesteña Grande Inferred Mineral Resource 5,733,000 0.119 13,601,000
Total Inferred Resources 6,996,000 0.120 16,793,000

Represents that portion of the in-place mineral resource that are estimated to be recoverable within existing wellfields. Wellfield recovery
factors have not been applied to indicated and inferred mineral resources. As reported in the NI-43-101 Technical Report Summary for the Alta
Mesa Uranium Project, Brooks and Jim Hogg Counties, Texas, USA completed by Doug Beahm, PE, PG, of BRS Engineering. (Effective January 19,


John M. Seeley, Ph.D., P.G., C.P.G., enCore’s Manager of Geology and Exploration, and a Qualified Person under NI 43-101, has reviewed and approved the technical disclosure in this news release on behalf of the Company.


About enCore Energy Corp.


enCore Energy Corp., America’s Clean Energy Company™, is committed to providing clean, reliable, and affordable fuel for nuclear energy as the newest uranium producer in the United States. Uranium production commenced at enCore’s licensed and past-producing South Texas Rosita Central In-Situ Recovery (“ISR”) Uranium Processing Plant in November 2023 with work underway for a planned Q2/2024 restart of uranium production at its licensed and past-producing South Texas Alta Mesa CPP. The enCore team is led by industry experts with extensive knowledge and experience in all aspects of ISR uranium operations and the nuclear fuel cycle. enCore solely utilizes ISR for uranium extraction, a well-known and proven technology co-developed by the leaders at enCore Energy. ISR extracts uranium in a wellfield using natural groundwater and oxygen, coupled with a proven ion exchange process, to recover the uranium.


Future projects in enCore’s production pipeline include the Dewey-Burdock project in South Dakota and the Gas Hills project in Wyoming, along with significant uranium resource endowments in New Mexico providing long term opportunities. enCore diligently works to realize value from other owned assets, including our proprietary uranium database that includes technical information from many past producing companies, from our various non-core assets, and by leveraging our ISR expertise in researching opportunities that support the use of this technology as applied to other metals. enCore is also committed to working with local communities and indigenous governments to create positive impact from corporate developments.


Posted March 18, 2024

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