DWQ-2025-003825

Joseph Beckstead
Mine Engineer
Redmond Minerals
2725 North 1000 West
P.O. Box 219
Redmond, UT 84652

Subject: GWPBR-25-005 - Ground Water Discharge Permit-By-Rule Determination and Issuance of the Construction Permit for Four Salt Brine Evaporation Ponds

Dear Mr. Beckstead:

The Division of Water Quality (DWQ) received a Ground Water Discharge Permit (GWDP) Application by email on March 14, 2025. The proposed project would be to construct Four Salt Brine
Evaporation Ponds on the surface directly over the salt deposit for the purpose of evaporating the saturated brine water. This would provide a sustainable means for managing the amount
of brine stored in the mine, as well as enabling the recovery of the salt dissolved in the brine for use in products.

Fully saturated salt brine accumulates inside the salt deposit in the underground mine workings as a result of natural groundwater infiltration around shafts, portals, and other man-made
openings into the salt, stormwater funneling into the mine around the portals, and mine operations that utilize fresh water for dissolution. Total incoming brine averages 7 to 8 million
gallons per year and is pumped to and stored in several sump locations throughout the upper mine levels.

The combined surface area of the four ponds would be about 13 acres, enabling the evaporation of approximately 10.4 million gallons of brine per year on average. The banks of the ponds
will be constructed with compacted natural in-situ soil. The ponds will be lined with a High-Density Polyethylene (HDPE) liner. This will help prevent overflow or leakage.

The ponds are described as follows:
Pond 1 – Area = 186,030 sq ft (4.27 acres), Max. Capacity = 6.5 million gallons (20 acre feet) Total Pond Depth = 10 ft, Max. Brine Depth = 4.7 ft, and Annual Evap ~ 3.37 million gallons/year.
Pond 2 – Area = 52,085 sq ft (1.2 acres), Max. Capacity = 2 million gallons (6.14 acre feet) Total Pond Depth = 10 ft, Max. Brine Depth = 5.2 ft, and Annual Evap ~ 940,000 gallons/year.
Pond 3 – Area = 170,000 sq ft (3.9 acres), Max. Capacity = 6 million gallons (18.4 acre feet) Total Pond Depth = 10 ft, Max. Brine Depth = 5 ft, and Annual Evap ~ 3.08 million gallons/year.
Pond 4 – Area = 164,500 sq ft (3.78 acres), Max. Capacity = 6 million gallons (18.4 acre feet) Total Pond Depth = 10 ft, Max. Brine Depth = 5 ft, and Annual Evap ~ 2.98 million gallons/year.

The ponds will be located directly over the salt deposit so that any brine that might leak would soak through the overlying salty alluvium and back into the salt deposit, ensuring that
no brine would leave the property or contaminate other soils or water.

The ponds would be filled with brine from the mine through the winter and allowed to evaporate through the spring, summer, and fall. Once a pond is sufficiently dry and the salt layer
is thick enough, the salt can be recovered for use in products. A sufficient layer of salt will always be maintained to protect the HDPE pond liner. The pond will then be refilled.

Below are the relevant factors evaluated in determining that the proposed operation qualifies for permit by rule and that the discharge will have a de minimis actual or potential effect
on ground water quality or beneficial uses of ground water resources.

The brine water being put into the evaporation ponds will be the natural groundwater seeping into the mine. No outside contaminants or other mine facility processes will be mixed with
the ground water to create “contact” water.

The four ponds will be located directly over the salt deposit so that any leakage would flow back into the mine workings.

PBR Conditions of Approval

The Evaporations Ponds may only be used for brine coming out of the salt mine. Nothing else may be put in the ponds.

Cease operations and notify DWQ immediately if a sheen or odor is detected on any of the brine in the ponds.

Based on the factors described above, the proposed evaporation ponds and any leakage from those ponds would flow back into the mine workings and would not present a threat to human health
or the environment and qualifies for permit-by-rule under UAC R317-6-6.2.A(25).

If any of these factors change because of changes in your operation or from additional knowledge of site conditions, this permit-by-rule determination may not apply and you should inform
the DWQ. If future project knowledge or experience indicates that ground water quality is threatened by this operation, the Director may require that you apply for a ground water discharge
permit in accordance with UAC R317-6-6.2.C.

This permit-by-rule determination is effective for a period of 5 years from the date of this letter. Prior to the end of this 5-year period, Redmond Minerals shall submit laboratory
analysis from a recent ground water sample from the French drain and re-apply for a permit-by-rule determination so the Director may confirm site conditions have not changed.

Construction Permit

The Division of Water Quality (DWQ) received a Ground Water Discharge Permit (GWDP) Application by email on March 14, 2025. This GWDP Application contained various drawings for the
four Brine Evaporation Ponds. However, the drawings had not been stamped by a Utah Certified Professional Engineer (P.E.). Also, the documentation did not contain the construction
specifications.

On April 21, 2025, DWQ received the construction plans and specifications. These were signed and stamped by Michael Forbush, P.E.

The following is a summary of the 4 HDPE lined brine evaporation ponds:

Pond 1 – Area = 186,030 sq ft (4.27 acres), Max. Capacity = 6.5 million gallons (20 acre feet) Total Pond Depth = 10 ft, Max. Brine Depth = 4.7 ft, and Annual Evap ~ 3.37 million gallons/year.
Pond 2 – Area = 52,085 sq ft (1.2 acres), Max. Capacity = 2 million gallons (6.14 acre feet) Total Pond Depth = 10 ft, Max. Brine Depth = 5.2 ft, and Annual Evap ~ 940,000 gallons/year.
Pond 3 – Area = 170,000 sq ft (3.9 acres), Max. Capacity = 6 million gallons (18.4 acre feet) Total Pond Depth = 10 ft, Max. Brine Depth = 5 ft, and Annual Evap ~ 3.08 million gallons/year.
Pond 4 – Area = 164,500 sq ft (3.78 acres), Max. Capacity = 6 million gallons (18.4 acre feet) Total Pond Depth = 10 ft, Max. Brine Depth = 5 ft, and Annual Evap ~ 2.98 million gallons/year.

The plans and specifications, as submitted, comply with the Utah Water Quality Rules, (R317, Utah Administrative Code). A Construction Permit is hereby issued as constituted by this
letter, subject to the following conditions:

Any revisions or modifications to the approved plans and specifications must be submitted to DWQ for review and approval, before construction or implementation thereof. Please submit
any changes for review and approval directly to Woodrow Campbell, P.E., of the DWQ Ground Water Protection Section.

A written operations and maintenance manual, containing a description of the functioning of the facilities, an outline of routine maintenance procedures, and all checklists and maintenance
logs needed for proper operation of the system, must be submitted and approved before the final inspection and operation of the system.

The approved facilities must not be placed in service unless DWQ has conducted a final inspection, reviewed and approved the As-Built Construction Certification Report, and provided
written authorization to place the constructed facilities in service.

Construction activities that disturb one acre or more are required to obtain coverage under the Utah Pollutant Discharge Elimination System (UPDES) Storm Water General Permit for Construction
Activities. The permit requires the development of a storm water pollution prevention plan (SWPPP) to be implemented and updated from the commencement of any soil disturbing activities
at the site until final stabilization of the project. For more information, or to obtain permit coverage on-line, please go to: https://deq.utah.gov/water-quality/general-construction-storm-water-updes-permits

The plans and specifications for this project have been stamped and signed by a Professional Engineer currently licensed to practice in the state of Utah. The construction design, inspection
supervision, and written construction certification of all work associated with this Construction Permit must be performed by a Professional Engineer licensed to practice in the state
of Utah.

This Construction Permit will expire one year from the date of its issuance, as evidenced by the date of this letter, unless substantial progress is made in constructing the approved
facilities or the plans and specifications have been resubmitted and the construction permit is reissued. This permit does not relieve you, in any way, of your obligations to comply
with other applicable local requirements. You may contact Eric Larsen, Central Utah Public Health Department at 385-505-5558 or John Chartier, DEQ District Engineer at 435-559-1969 for
further assistance regarding local matters.

Please contact Mr. Campbell at the beginning of construction to allow periodic inspections to be scheduled. Upon completion of the project, a final inspection and approval of the As-Built
Construction Certification Report is required before the approval to operate the completed facilities can be issued. Please remain in contact with Mr. Campbell to schedule the final
inspection. The Construction Certification Report with final as-built drawings must include test results for the following construction quality assurance and quality control (CQA/QC)
elements:
Soil Subgrade
Proctor Curves;
Soil Classification;
Field Compaction Testing; and
Subgrade Acceptance Certification.

Flexible Membrane Liner
Panel Placement Log;
Trial Seam Test Log;
Seaming Record;
Seam Test Record;
Repair Log;
As-Built Drawing;
Manufactures Certification including QA/QC Testing of the Rolls; and

Professional Engineer Certification.

If you have any questions about this letter, please contact Woodrow Campbell at [phone] or [e-mail].

Sincerely,

John K. Mackey, P.E.
Director

cc: John Chartier, Central Utah District Engineer (via email)
Central Utah Public Health Department (via email)
Joseph Beckstead, Redmond Minerals ([e-mail])

Joseph Beckstead
Page 2

195 North 1950 West • Salt Lake City, UT
Mailing Address: P.O. Box 144870 • Salt Lake City, UT 84114-4870
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