DWQ-2025-004033

UIC Permit No. UTU-27-AP-BDCCF0C
ATTACHMENT A
General Location Map of the ACES Storage Project, Millard County.
UIC Permit No. UTU-27-AP-BDCCF0C
Attachment B
Map of the ACES I Storage Project
Area of Review (AOR) including the Class V Permit Area
FIGURE:DESCRIPTIONDATENo.
DRAWN BY:DESIGNED BY:CHECKED BY:
DATE:SCALE:
APPROVED:
DIMENSIONS:
DRAWING DATA
UIC PERMIT BOUNDARY 3165 E. MILLROCK DR, SUITE 330
HOLLADAY, UTAH 84121
PHONE: [phone]www.westernenergyhub.com
ACES DELTA
00 2000' 4000'
LEGEND
ACES Delta Solution Mining, LLC
UIC PERMIT BOUNDARY
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FIGURE:DESCRIPTIONDATENo.
DRAWN BY:DESIGNED BY:CHECKED BY:
DATE:SCALE:
APPROVED:
DIMENSIONS:
DRAWING DATA
UIC PERMIT BOUNDARY 3165 E. MILLROCK DR, SUITE 330
HOLLADAY, UTAH 84121
PHONE: [phone]www.westernenergyhub.com
ACES DELTA
00 1 mi.2mi.
LEGEND
ACES Delta Solution Mining, LLC
UIC PERMIT BOUNDARY
PROJECT BOUNDARY
AREA OR REVIEW
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ACES Delta Solution Mining, LLC
New UIC Boundary
Commencing at the Southeast corner of Section 22, Township 15 South, Range 7 West,
Salt Lake Meridian; thence North 89°17'52" West 2655.50 feet along section line to the
South quarter corner of said Section 22; thence North 89°19'02" West 2654.79 feet
along section line to Southwest corner of Section 22; thence North 00°44'02" East
2642.33 feet along section line to the West quarter corner of said Section 22; thence
North 00°45'42" East 2432.13 feet along section line to its intersection with the southerly
right-of-way line of Brush Wellman Road; thence South 77°07'04" East 874.24 feet
along said right-of-way; thence South 70°46'11" East 12168.97 feet along said right-of-
way; thence South 52°19'38" West 5959.27 feet; thence North 88°31'10" West 2433.34
feet to the East quarter Corner of Section 27, Township 15 South, Range 7 West, Salt
Lake Meridian; thence North 89°17'28" West 5301.39 feet along quarter section line to
the West quarter corner of said Section 27; thence North 00°54'37" East 2642.81 feet
along section line to the POINT OF BEGINNING. Contains 62716123 square feet or
1439.764 acres, more or less.
LESS AND EXCEPTING - Commencing at the Southwest corner of Section 23; Township
15 South, Range 7 West, Salt Lake Meridian; thence North 00°18'23" East 1111.06 feet
along section line to the POINT OF BEGINNING; thence North 64°34'46" East 73.91 feet;
thence South 73°49'13" East 279.34 feet; thence South 00°00'19" West 263.15 feet;
thence North 89°42'45" East 146.57 feet; thence North 41°28'46" East 177.23 feet; thence
North 89°34'42" East 225.12 feet; thence South 64°31'09" East 305.28 feet; thence South
00°23'34" East 717.88 feet; thence South 65°16'04" East 235.54 feet to a point on the
northerly line of Section 26, T15S, R7W, SLM; thence continuing in said section 26 South
65°16'04" East 207.43 feet; thence South 01°23'26" East 1169.62 feet; thence West
401.20 feet; thence North 4.28 feet; thence North 22°43'27" West 467.23 feet; thence
South 79°11'34" West 288.07 feet; thence North 51°06'56" West 329.45 feet; thence
South 56°39'43" West 187.05 feet; thence South 89°59'34" West 122.48 feet to a curve
to the right having a radius of 209.79 feet, a central angle of 45°07'59" and a chord that
bears North 67°26'27" West 161.02 feet; thence along said curve northwesterly an arc
distance of 165.26 feet to a point on the easterly line of Section 27, T15S, R7W, SLM;
thence continuing in said Section 27 along the arc of said curve to the right having a
radius of 209.79 feet, a central angle of 20°06'21", and a chord that bears North 34°49'17"
West 73.24 feet; thence North 24°46'07" West 122.64 feet; thence North 15°42'36" East
172.98 feet; thence North 00°34'51" East 174.69 feet; thence South 87°34'12" West
258.30 feet; thence North 01°33'30" East 219.21 feet to the southerly line of Section 22,
T15S, R7W, SLM; thence South 89°50'49" East 239.59 feet along section line; thence in
Said Section 22 North 52°10'01" West 120.19 feet; thence North 30°04'41" West 97.90
feet; thence South 80°30'37" West 242.82 feet; thence North 77°33'20" West 185.78 feet;
thence North 24°20'04" West 190.91 feet to a curve to the right having a radius of 350.00
feet, a central angle of 30°50'30" and a chord that bears North 08°54'49" West 186.13
feet; thence along said curve northerly an arc distance of 188.40 feet; thence North
06°30'26" East 200.06 feet; thence North 06°22'38" West 309.11 feet; thence North
06°38'54" East 184.56 feet; thence North 43°13'03" East 145.85 feet; thence North
85°51'44" East 204.23 feet; thence South 61°59'15" East 237.38 feet; thence South
07°46'26" East 147.72 feet; thence South 89°44'16" East 110.58 feet; thence North
64°34'46" East 98.93 feet to the POINT OF BEGINNING. Contains 3388367 square feet
or 77.786 acres, more or less.

3/20/2024
File: UICBndry-REV4-2024.ndpScale: 1 inch= 1597 feet
Tract 1: 1439.7641 Acres, Closure: s80.5633w 0.01 ft. (1/999999), Perimeter=34454 ft.
Tract 2: 77.7828 Acres, Closure: s15.0334e 0.02 ft. (1/418887), Perimeter=9691 ft.
n00°44'02"e
2642.33
n00°45'42"e
2432.13
5
s70°46'11"e12168.97
s 5 2 °1 9'3 8"w
5 9 5 9.2 7
n88°31'10"w
2433.34n89°17'28"w
5301.39
n00°54'37"e
2642.81
Tract Data and Deed Calls: File= UICBndry-REV4-2024.ndp
Tract 01: 1439.7641 Acres, Closure: s80.5633w 0.01 ft. (1/999999), Perimeter=34454 ft.
Tract 02: 77.7828 Acres, Closure: s15.0334e 0.02 ft. (1/418887), Perimeter=9691 ft.
Tract 02: 77.7828 Acres, Closure: s15.0334e 0.02 ft. (1/418887), Perimeter=9691 ft.
1: /n89.1752w 2655.5
2: /n89.1902w 2654.79
3: n00.4402e 2642.33
4: n00.4542e 2432.13
5: s77.0704e 874.24
6: s70.4611e 12168.97
7: s52.1938w 5959.27
8: n88.3110w 2433.34
9: n89.1728w 5301.39
10: n00.5437e 2642.81
11: @0
12: /n00.1823e 1111.06
13: n64.3446e 73.91
14: s73.4913e 279.34
15: s00.0019w 263.15
16: n89.4245e 146.57
17: n41.2846e 177.23
18: n89.3442e 225.12
19: s64.3109e 305.28
20: s00.2334e 717.88
21: s65.1604e 235.54
22: s65.1604e 207.43
23: s01.2326e 1169.62
24: s90w 401.2
25: n0e 4.28
26: n22.4327w 467.23
27: s79.1134w 288.07
28: n51.0656w 329.45
29: s56.3943w 187.05
30: s89.5934w 122.48
31: curve right radius 209.79 arc 165.26 chord dir n67.2627w chord dist 161.02
32: n34.4917w 73.24
33: n24.4607w 122.64
34: n15.4236e 172.98
35: n00.3451e 174.69
36: s87.3412w 258.3
37: n01.3330e 219.21
38: s89.5049e 239.59
39: n52.1001w 120.19
40: n30.0441w 97.9
41: s80.3037w 242.82
42: n77.3320w 185.78
43: n24.2004w 190.91
44: curve right radius 350 arc 188.4 delta 030.5030 chord dir n08.5449w chord dist 186.13
45: n06.3026e 200.06
46: n06.2238w 309.11
47: n06.3854e 184.56
48: n43.1303e 145.85
49: n85.5144e 204.23
50: s61.5915e 237.38
51: s07.4626e 147.72
52: s89.4416e 110.58
53: n64.3446e 98.93
UIC Permit No. UTU-27-AP-BDCCF0C
ATTACHMENT C
Hydrogen Storage Cavern Field Operating, Monitoring and Reporting Plan
Hydrogen
Storage Cavern
Field Operating,
Monitoring and
Reporting Plan
Class V Underground
Injection Control Permit
(UTU-27AP-BDCCF0C)
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Hydrogen Storage Cavern
Field Operating, Monitoring, and
Reporting Plan (Draft)

Class V Underground Injection
Control Permit
UTU-27AP-BDCCF0C
Advanced Clean Energy Storage I, LLC
(A Wholly Owned Subsidiary of Aces Delta, LLC) Delta, Utah
February 2025
Prepared by
Advanced Clean Energy Storage I, LLC 3165 E. Millrock Dr., Suite 330 Holladay, Utah 84121 Tel [phone] Fax [phone] www.magnumdev.com

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Hydrogen Cavern Field Operating Plan i February 2025
Table of Contents
Section 1 Introduction................................................................................................................................... 1-1
1.1 Plan Purpose ....................................................................................................... 1-1
1.2 Facility Location ................................................................................................. 1-1
1.3 Facility Description............................................................................................. 1-1
1.4 Jurisdictional Oversight and Basis for Plan Parameters ..................................... 1-2
1.5 Storage Cavern Field Description and Design Parameters ................................. 1-6
1.6 Storage Cavern and Cavern Well Description .................................................... 1-6
Section 2 Operations Procedure .................................................................................................................. 2-1
2.1 Storage Cavern Field .......................................................................................... 2-1
2.1.1 Site Security and Emergency Planning and Response Plan ................... 2-1
2.1.2 Corrosion Control .................................................................................. 2-1
2.2 Storage Cavern and Cavern Well System ........................................................... 2-1
2.2.1 Operating Pressures ............................................................................... 2-1
2.2.2 Cavern Capacity and Geometry ............................................................. 2-2
2.2.3 Cavern Maintenance and Enlargement Activities .................................. 2-3
2.2.4 Solution Mining Activities..................................................................... 2-3
Section 3 Maintenance Procedures ............................................................................................................. 3-1
3.1 Storage Cavern Field .......................................................................................... 3-1
3.1.1 Monitoring ............................................................................................. 3-1
3.1.2 Testing and Inspection ........................................................................... 3-2
3.2 Storage Cavern and Cavern Well System ........................................................... 3-2
3.2.1 Monitoring ............................................................................................. 3-2
3.2.2 Testing and Inspection ........................................................................... 3-5
3.2.3 Embrittlement Management .................................................................. 3-8
Section 4 Agency Reporting and Notification............................................................................................. 4-1
4.1 Storage Cavern Field .......................................................................................... 4-1
4.2 Storage Cavern and Cavern Well System ........................................................... 4-2
Section 5 Records Retention ........................................................................................................................ 5-1

Figures
Figure 1. Vicinity Map ................................................................................................................ 1-2
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Hydrogen Cavern Field Operating Plan ii February 2025
Figure 2. Facilities Map .............................................................................................................. 1-5
Figure 3. Hydrogen Storage Cavern Component Diagram ......................................................... 1-7

Tables
Table 1. Hydrogen Storage Cavern Summary ............................................................................ 1-6

Appendices
Appendix A: Storage Cavern Wellhead Gauge Summary Tables Appendix B: Cavern Inventory Verification Methodology (Indirect/Model-Based and
Direct/Real-Time Measurement) Appendix C: Subsidence Monitoring Plan
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Hydrogen Cavern Field Operating Plan 1-1 February 2025
Section 1 Introduction
1.1 Plan Purpose
This Plan has been developed to outline clear processes and procedures for the operation and
maintenance, monitoring, testing and inspection, and agency reporting of the Hydrogen Storage Cavern Field at the Advanced Clean Energy Storage I, LLC (Company) Hydrogen Production and Storage facility (Facility). The operation of the Hydrogen Storage Cavern Field is under the jurisdiction of the Utah Department of Environmental Quality, Division of Water Quality (DWQ). The Company has created this enforceable Plan, to meet the requirements for the operation of salt
storage caverns under DWQ Class V UIC Permit UTU-27AP-BDCCF0C and in accordance with the applicable methods identified in 40 CFR 146.33 and 40 CFR 146.8 and other acceptable industry standard methods. This Plan has been reviewed and approved by the DWQ. Any future modifications to this Plan requested by the Company are subject to approval by DWQ. DWQ may also modify the Plan after it receives new, previously unavailable information or after a review of
the Plan. A copy of the Plan will be kept at the facility and on file with DWQ.
1.2 Facility Location
The Facility is located approximately eight miles north of Delta in Millard County and on lands leased from the Utah School and Institutional Trust Lands Administration (SITLA). As shown on Figure 1, it is situated west of Highway 6 near the intersection of Jones Road and Brush Wellman Road/SR-174.
1.3 Facility Description
The Facility is located above a salt dome that is approximately one mile thick, two miles in
diameter and 3,000 feet below the ground surface. The Company will be solution mining storage caverns within the salt dome for the purpose of storing hydrogen gas. Figure 2 is a map depicting the storage facility layout as currently proposed. As shown, the facility components include a Storage Cavern Field with two caverns initially (CW-2 and CW-23), two brine evaporation ponds, a large-scale electrolyzer plant to produce hydrogen, and utilities interconnecting the components.
The utilities interconnecting the components include brine, water, and hydrogen gas pumping and pipeline systems, and power and communications lines. Eventually the facility will be capable of storing up to 60 million kilograms of hydrogen gas in up to five approximately 21,000 metric tons (5.5 million barrels) caverns. The timing for the construction of each cavern will be solely dependent upon market demand.

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Hydrogen Cavern Field Operating Plan 1-2 February 2025

Figure 1. Vicinity Map

1.4 Jurisdictional Oversight and Basis for Plan Parameters
The DWQ Class V UIC Permit is the principal approval for the operation of the storage caverns.
This permit corresponds with the DWQ Class III UIC Permit (UTU-27-AP-718D759) that
authorizes construction of the storage caverns. This Plan is enforceable under the Class V UIC Permit and there are two other enforceable plans that are associated with this Plan under the Class III UIC Permit: Hydrogen Cavern Construction and Development Plan (CCDP) and Hydrogen Monitoring, Reporting and Recording Plan (MMRP). The Company has completed an extensive regulatory process with the DWQ to support the issuance of the Class III and V UIC Permits. This
regulatory process led to the development of the current parameters in all three enforceable plans and include: standards for the layout of the storage cavern field: siting criteria for caverns within the field; a typical engineering design for the individual caverns; and, construction, solution mining and operations and maintenance parameters.
This basis for these parameters includes a series of geomechanical analyses, cavern engineering
design studies, and specific engineering designs for hydrogen storage that were completed by the Company from 2009 to 2020. The geomechanical analyses and cavern engineering design studies established the strength and suitability of the salt dome to support solution mined caverns, the range of cavern sizes that can be developed, the required cavern spacing and optimum cavern operating conditions and parameters. The specific engineering designs also outline parameters and
procedures for:
 cavern well drilling and construction;
 cavern well casing design and installation;
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Hydrogen Cavern Field Operating Plan 1-3 February 2025
 storage cavern solution mining;
 storage cavern operations and maintenance;
 monitoring, mechanical integrity, and other required testing (MIT) for both the cavern
wells and storage caverns as an integrated system prior to and during operations; and,
 general plugging and abandonment procedures.
The Company has obtained the other required state and local permits authorizing the construction and operation of the brine evaporation pond and electrolyzer plant and the facility has been
designed to meet all applicable federal, state and local engineering design and safety regulations
and standards to include those required by the Occupational Safety and Health Act of 1970 (OSHA), Sections 4, 6, and 8; 29 CFR 1910.103 Subpart H - Hazardous Materials, National Fire Protection Association (NFPA) 2 Hydrogen Technologies Code, and other applicable NFPA and International Code Council (ICC) safety, fire, electrical and mechanical codes. These regulations
and standards require specific engineering design criteria for all facility components, redundant
safety features on handling and storage process related equipment, and offsets relative to the interior layout of the facility and existing buildings and infrastructure on adjacent properties.

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Hydrogen Cavern Field Operating Plan 1-4 February 2025

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Hydrogen Cavern Field Operating Plan 1-5 February 2025
Figure 2. Facilities Map

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Hydrogen Cavern Field Operating Plan 1-6 February 2025
1.5 Storage Cavern Field Description and Design Parameters
The Company has designed the Facility in accordance with a larger Master Plan that has distinct use areas. The storage cavern field is a dedicated area within the Facility intended only for the construction and operations of storage caverns. Having a dedicated area allows the Company to
develop standardized parameters for the siting, construction, operation and maintenance of all caverns in the field. As stated, figure 2 depicts the locations for the first two caverns to be constructed within the field as well as the broader Facility layout. Table 1 below provides the location and intended size of the first two caverns to be constructed. This table will be updated as each of the caverns are constructed.
Table 1. Hydrogen Storage Cavern Summary
Cavern Name Surveyed Location (Lat/Long) Cavern Capacity (total space)
CW-23 N39°29'41.15476" W112°36'15.33298" 5.5 mmbbls (planned size)
CW-2 N39°29'53.14153" W112°36'25.52534" 5.5 mmbbls (planned size) Storage caverns within the field will be designed to ensure that the minimum required cavern spacing and depth is met when siting, constructing, operating and maintaining all caverns. The minimum spacing requirement is a condition of both the Class III and V UIC permits as defined
by geomechanical studies completed for the Facility. The minimum required spacing between two adjacent solution mined caverns is required to be no less than a 2:1 P:D ratio, where P equals the distance between the two cavern boundaries and D equals the average of the maximum diameter of the two caverns. On the surface, this translates to cavern wells being no less than 600 – 700 feet apart to accommodate a final 21,000 metric tons/5.5 mmbbl cavern volume with dimensions of
approximately 220 to 350 feet in diameter and 1200 feet in height. Geomechanical analysis, the site-specific geological conditions within the salt body, and the minimum pillar requirement will ultimately dictate the final dimensions of each individual cavern.
1.6 Storage Cavern and Cavern Well Description
Storage cavern construction begins with drilling and installation of the cavern well in accordance with the applicable federal and state rules (40 C.F.R. § 146.32, UAC R649-3-13 and UAC R649-
3-7.4) and requirements of the DWQ Class III UIC Permit. The drilling and installation procedures
for the cavern well are outlined in the CCDP. During the drilling and installation of the cavern well, each casing is set, cemented and pressured tested as outlined in the MMRP. The storage cavern design includes a well head and cavern well with five cemented casings and two hanging strings (Figure 3). The well head and hanging strings are used both during the solution mining
process and hydrogen storage once the cavern is placed into operation. The cemented casing design
also serves two purposes: 1) to provide long-term mechanical integrity of the cavern well and storage cavern; and, 2) to protect groundwater contamination with the installation of one cemented casing to the top of the salt and two cemented casings into the salt.
Drilling and installation of the cavern well will also be completed in accordance with the
Formation Testing Plan described in the CCDP in order to mitigate potential effects if an insoluble
zone within the salt cavern stratigraphy is identified that would require a design change. If an insoluble zone is detected in the vicinity of the casing shoe, the shoe will be relocated to incorporate a 50 ft offset from the insoluble zone and 150 ft offset from the cavern roof. These
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Hydrogen Cavern Field Operating Plan 1-7 February 2025
offsets can be adjusted if an updated geomechanical study is completed by the Company to support the adjustment.
Once the wellhead, cemented casings and hanging strings for solution mining have been set, a final
pressure test is conducted (with the exception of the interior of the inner 8 5/8” string) as described in the MMRP to verify the installation and integrity of all components on the cavern well prior to the commencement of solution mining. Appendix A includes the typical wellhead pressures during solution mining and hydrogen storage. As each storage cavern is constructed, Appendix A will be
updated to include a wellhead schematic depicting the location of the pressure gauges.
Figure 3. Hydrogen Storage Cavern Component Diagram

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Hydrogen Cavern Field Operating Plan 1-8 February 2025
After the cavern well is installed, the storage cavern will be constructed using conventional solution mining technology and freshwater displacement of hydrogen for purposes of cavern
enlargement during operations. Depending upon the cavern size, solution mining can take between
18 and 24 months to complete. The solution mining process required by the Class III UIC Permit and outlined in the MMRP for individual caverns is provided below for reference:
 After the cavern well is constructed, a double string of hanging casing (an inner and outer hanging casing) will be placed into the open hole, and a wellhead is assembled.
 A nitrogen blanket is injected into the cavern well to a level about 200 feet below the final
cemented casing shoe. The nitrogen blanket serves to keep solution mining activity below the final cemented casing shoe in order to maintain integrity and to control the shape and development rate of the cavern.
 Fresh water is injected at approximately 2,500 gallons per minute (gpm) through the inner
or outer hanging casing and withdrawn through the annular space between the inner and
outer casing or the inner string.
 Injected water is circulated in the well hole to dissolve salt and then transferred to the brine evaporation pond for storage and evaporation.
 The cavern shape is measured and monitored using sonar surveys during the solution
mining process.
 Solution mining is stopped when the designed cavern volume is reached, the hanging strings used during solution mining are removed and a sonar survey and final MIT is completed.
 Hanging strings for use during cavern operation are installed in anticipation of the cavern
being placed into commercial service.
 Only a successful MIT as determined by DWQ will allow the cavern to be placed into service.
Once the DWQ has determined a successful MIT has been completed, the jurisdictional requirements for the operations and maintenance of individual caverns will be transferred to the
DWQ Class V UIC permit.
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Hydrogen Cavern Field Operating Plan 1-9 February 2025

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Hydrogen Cavern Field Operating Plan 2-1 February 2025
Section 2 Operations Procedure
The Company will operate and maintain the storage cavern field components in accordance with the DWQ Class III and V UIC Permits and all other applicable permits and regulatory requirements. The operations and maintenance procedures described below were developed in cooperation with the respective jurisdictional agencies and are based on the requirements described
in 40 CFR 146.33 and 40 CFR 146.8. The procedures also incorporate industry standards and
practices that provide a foundation for the safe operations of the individual cavern well/storage cavern system and facility. The applicable regulations, codes and standards include requirements for the design, materials and equipment selection used during construction and also dictate the operations procedures of the storage cavern field and individual caverns. The procedures are
therefore organized by the activities associated with these two components to ensure safe
operations and mechanical integrity of the integrated system as a whole. Storage Cavern Field
2.1.1 Site Security and Emergency Planning and Response Plan
A Site Security and emergency planning and response plans will be established per the regulatory requirements of OSHA, NFPA, ICC, and Millard County. Copies of these plans will be placed on file with any relevant jurisdictional agencies and kept on file at the storage facility. The Site
Security Plan will describe the design and establish procedures to control and maintain access to the site. The standard operating procedures and emergency planning and response plans will for the Facility will include the design for the facility-wide emergency shut-down system (ESD) that will initiate if a leak or loss in cavern pressure is detected. The ESD system is designed to contain any leak as well as isolate the affected equipment to protect other areas in the facility until a repair
can be made. The standard operating procedures will provide the routine maintenance and testing procedures for the ESD system and the emergency planning and response plans will provide detailed procedures to ensure the safety of personnel and the community. These plans will also provide detailed procedures for the investigation, remediation, and reporting requirements following the management of a leak. A copy of these procedures and plans will be kept on file at
the Facility. 2.1.2 Corrosion Control A facility-wide cathodic protection system will be installed to protect the surface infrastructure, to include the cavern wellhead and facility piping. The system will be designed to continuously
mitigate environmental factors that can induce corrosion on facility components. It will consist of
deep anode groundbeds. The groundbeds will be installed at each of the operating storage caverns, on each of the hydrogen distribution lines, and other surface support equipment as necessary. The cathodic protection system will be expanded as additional storage caverns and support facilities are constructed and placed into operations. During operations, maintenance will include monthly
inspections and an annual third-party survey as described in Section 3.
2.2 Storage Cavern and Cavern Well System
2.2.1 Operating Pressures
The operating pressure of each integrated storage cavern and cavern well system will be maintained at all times during cavern operations to ensure an exceedance of the allowable
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Hydrogen Cavern Field Operating Plan 2-2 February 2025
thresholds does not occur. The Class III UIC Permit established a minimum allowable operating
pressure gradient (MinAOPG) of 0.25 pounds per square inch per foot of depth to the last cemented casing shoe and a maximum allowable operating pressure gradient (MaxAOPG) of .80 pounds per square inch per foot of depth to the last cemented casing based on the initial geomechanical analyses for the salt formation as a whole. To determine a safe operating envelope within these pressures requirements, the Company completed additional geomechanical analyses that take into
consideration hydrogen as the stored product type and the specific equipment designs to meet commercial delivery requirements. Based on these studies, the following MinAOPG, and MaxAOPG will be required at all times during operations and maintenance:
• A MinAOPG of 0.30 pounds per square inch per foot of depth;
• A MaxAOPG of 0.80 pounds per square inch per foot of depth; and,

The pressure of each cavern will be maintained and monitored at the wellhead by a facility-wide control system that sets and monitors the pressure and temperature as well as continuously
monitors hydrogen injection and withdrawal. To verify the actual pressure and temperature
conditions within the cavern, a fiber optic interrogator will also be installed along the length of the hanging string with multiple gauges to obtain pressure and temperature profiles at various intervals. This information will be converted in pressure and temperature values that can then be used to verify the cavern inventory against the injection and withdrawal measurements monitored
at the wellhead.
Both the wellhead control system and fiber optic interrogator will be integrated with the ESD system so that if a significant deviation in cavern pressure is detected, the ESD system will initiate and isolate that cavern from Facility until it can be assessed. To avoid unnecessary or false shut-downs, the Facility will use pressure calculations that are conservative during injection and
withdrawal. In the event of pressure gradient reaching 0.80 psi/ft of depth at the casing shoe during
the initial hydrogen fill or during normal operations, the injection compressors will be interlocked and will shut down. A copy of the ESD Valve system one line will be kept on file at the Facility.
2.2.2 Cavern Capacity and Geometry
The established geomechanical parameters for the cavern capacity and geometry of the individual hydrogen storage caverns and the cavern field will not be exceeded during operations. As described
in the geomechanical studies on file with the DWQ, the parameters are the modeled or design
criteria for a fully solution mined cavern to the designed 21,000 metric tons/5.5 mmbbl size (capacity) and shape (geometry) within the salt formation (depth and spacing between caverns) that if maintained during operation will provide overall geomechanical integrity. The parameters include:
o Salt thickness is a minimum of 4.0 cavern diameters above the cavern;
o The casing seat is a minimum of 200 ft above the cavern roof;
o The cavern diameter is variable due to site specific geologic conditions and will
range from 220-350 ft. Final geometry is dictated by geomechanical analysis;;
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Hydrogen Cavern Field Operating Plan 2-3 February 2025
o The cavern height is less than or equal to 1,590 feet1;
o The cavern storage volume remains less than or equal to 21,000 metric tons or 5.5
million barrels;
o The minimum pillar-to-diameter (P:D) ratio between caverns is no less than 2:1;
o The cavern shape remains similar to the proposed hydrogen storage cavern geometry
evaluated by historical geomechanical studies with no evidence of major salt falls;
o Initial and periodic sonar surveys do not indicate failure of the insoluble interbed or
preferential dissolution of highly soluble material beyond the periphery of the cavern envelop evaluated by historical geomechanical modeling; and,
o The distance from the outer cavern wall to the edge, or flanks, of the salt formation
is a minimum of 500 ft.
If cavern capacity monitoring and mechanical integrity testing activities described in Section 3 indicate these geomechanical parameters have not been maintained during operations, then the Company will complete a new geomechanical report for the specific cavern that does not meet the criteria listed above2 to ensure continued mechanical integrity. The Company will also track and verify the hydrogen inventory within the storage cavern as an additional means to verify both
cavern capacity and mechanical integrity. The monitoring activities to verify cavern inventory are described in Section 3 and Appendix D.
2.2.3 Cavern Maintenance and Enlargement Activities
The Company may inject freshwater periodically as part of routine maintenance to recover cavern capacity that is lost due to salt creep and to desalinate the hanging strings. The Company may also want to inject freshwater to displace hydrogen product to enlarge the overall size of a cavern after
it has been placed into operations if the cavern was not the planned 21,000 metric tons/5.5 mmbbl size. Cavern enlargement through freshwater displacement rather than saturated brine is authorized by the Class III UIC under specific conditions and if initiated will follow the procedures provided in the CCDP.
After any cavern reaches its planned capacity or the limits of the minimum cavern spacing
requirement described in Section 1, the Company understands that any injection of freshwater injection will only be used for the purpose of routine maintenance only to recover space associated with salt creep unless a new geomechanical study is submitted and approved by the DWQ that would support an increase in the final cavern size.
2.2.4 Solution Mining Activities
The Company may also reinitiate solution mining to enlarge the overall size of a cavern after it
has been placed into operations if the cavern was not the planned 21,000 metric tons/5.5 mmbbl size. Solution mining a cavern is a faster method than using freshwater displacement and is also authorized under the Class III UIC under specific conditions and if initiated will follow the
1 Measured from the bottom hole depth of the well at start of solution mining. The bottom of the cavern will fill with water-insoluble material during solution mining and minor spalling of the cavern walls can be expected during storage operations preventing the sonar survey from imaging the solid rock wall of the cavern sump. 2 Company historically prepared a number of geomechanical studies using a facility-specific approach. The modeling criteria of those studies
dictated the siting and development of all caverns within the field for both the storage of liquid and gaseous products. These facility-specific and product-specific criteria can also be modified in this Operating Plan if a new cavern specific or facility specific geomechanical study is provided as supporting evidence for DOGM to authorize the change.
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Hydrogen Cavern Field Operating Plan 2-4 February 2025
procedures provided in the CCDP. After any cavern reaches its planned capacity or the limits of
the minimum cavern spacing requirement, the Company understands additional growth through solution mining will no longer be allowed unless a new geomechanical study is submitted and approved by the DWQ to support an increase in the final cavern size.

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Hydrogen Cavern Field Operating Plan 2-5 February 2025

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Hydrogen Cavern Field Operating Plan 3-1 February 2025
Section 3 Maintenance Procedures
The Company will maintain the mechanical integrity of the storage cavern field and storage cavern
and cavern well systems during operations in accordance with the DWQ Class III and V UIC
Permits, the operating, monitoring and reporting requirements of 40 CFR 146.33, the mechanical integrity requirements of 40 CFR 146.8, and procedures based on applicable industry standards such as API 1170. The purpose of these requirements is to ensure safe operations from both a mechanical integrity and groundwater protection perspective. Specifically, the maintenance
procedures outlined below include monitoring, testing and inspection of the storage cavern field
and the storage cavern and cavern well system (cavern well and wellhead). The procedures are designed to maintain the components as both discrete components and as an integrated system to ensure no significant leaks and no significant fluid movement into an underground source of drinking water will occur during operations.
3.1 Storage Cavern Field
3.1.1 Monitoring
3.1.1.1 Ground Subsidence
In accordance with federal and state regulations, a Subsidence Monitoring Plan has been developed
to monitor for potential ground subsidence associated with the solution mining and/or operation of the storage caverns. Monitoring activities will be completed using a network of existing and new survey monuments, benchmarks, and wellhead survey points to establish a monitoring baseline and annual monitoring and reporting. A copy of the Subsidence Monitoring Plan, included
as Appendix C, is on file at the storage facility. A short summary of the subsidence monitoring
procedures is provided below:
 An initial baseline elevation survey will be completed prior to the start of solution mining activity at the Facility using network of survey monuments, benchmarks, and wellhead survey points that are either existing or will be installed.
 The monuments, benchmarks, and wellhead survey points are based on the following
criteria:
o A stable reference monument is located approximately 6000 feet beyond the center of the expected subsidence zone to provide a stable point that will not be influenced by the caverns.
o Local subsidence monitoring points consisting of new and existing monuments, or
points at wellheads, will be established according to the Subsidence Monitoring Plan included in Appendix C to provide point monitoring as well as a network from which overall movement can be inferred.
 Elevation surveys will be conducted quarterly for the first year of operations and then
annually thereafter.
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Hydrogen Cavern Field Operating Plan 3-2 February 2025
 Surveys will be conducted with precise level surveys. The survey will be conducted in loops with the loops closed. This method provides for better accuracy (+/- 0.01 ft.) than other typically used survey methods.
 Level measurements will be accurate to 0.01 foot.
 If a benchmark is changed, the elevation change from the previous benchmark will be noted in the elevation survey report.
 If any wellhead work results in a change in the survey point at the wellhead, the Company will submit the elevation before and after the wellhead work.
 All elevation surveys will be conducted by a licensed professional land surveyor.
The Company will report significant elevation changes identified during monitoring as outlined in Section 5 below.
3.1.2 Testing and Inspection
3.1.2.1 Corrosion Control
Testing and inspection of the corrosion control system consists of both a monthly and annual
activities. Monthly testing and inspection of the system includes the recording of ampacity
readings at each rectifier station to ensure proper system function and the verification of voltage and current to test for proposer rectifier operation. If an ampacity reading at any rectifier demonstrates a deficiency in the system, the deficiency will be addressed within 30 days of identification where there is no risk posed to health, safety, or the environment. Annual testing and
inspection of the system will entail a third-party survey of the system to test the integrity of the
system. If a deficiency(s) with the system is identified during either a monthly or annual testing and inspection where there is a risk to health, safety, and environment, the deficiency(s) must be immediately addressed.
3.2 Storage Cavern and Cavern Well System
3.2.1 Monitoring
3.2.1.1 Operating Pressures
The operating pressure of all storage cavern and cavern well systems will be monitored and
maintained as a system continuously at the wellhead and verified by a fiber optic interrogator
installed within the cavern. Pressure measurements will be taken at the using pressure gauges and transmitters that are installed on the wellhead according to the following method:
 Pressure transmitters will be linked to the system programmable logic controller (PLC), which provides the capability of continuous pressure recording.
 Each of the pressure transmitters will record the maximum and minimum operating
pressures during a 24-hour period.
 Each pressure transmitter detects operating pressures continuously with interlocks to the wellhead injection and facility ESD systems.
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Hydrogen Cavern Field Operating Plan 3-3 February 2025
In addition to monitoring cavern conditions at the wellhead, temperature and pressure measurements will be collected by the fiber optic interrogator at various points within the cavern as a means of verifying in situ cavern conditions. This system will provide more accurate data that
can be used for both maintaining cavern pressure and verification of hydrogen inventory in the
cavern discussed in more detail below.
3.2.1.2 Leak Detection
LEL devices (gas detectors) will also be installed at each cavern wellheads to continuously monitor for gas leakage. These devices are all tied to the facility’s control system and data historian. In the event any leak is detected at the wellhead, the facility ESD system will engage to both isolate the
individual well and shut down operations of the entire facility until the cause of the leak and risk
to other systems have been assessed.
3.2.1.3 Cavern Capacity and Geometry
The capacity and geometry of each individual cavern will be monitored periodically in accordance with permit requirements and industry standards. The periodic verification of cavern shape, size
and roof thickness will be scheduled at the same time as the required mechanical integrity testing.
The purpose of this monitoring is to ensure individual caverns meet the established geomechical parameters described in Section 2. The monitoring methods will include:
 To establish an accurate baseline of the cavern capacity and geometry, the first sonar survey will be completed with the hanging strings removed to allow for a full view of the roof.
 Subsequent sonar surveys will be completed using either a through-pipe method or a
method that involves the removal or “snubbing up” of the hanging strings which can still provide a full view of the roof but does not involve a full workover of the cavern well.
 Surveys will be completed at the following times during operations at a minimum:
o before placing the storage cavern into operations;
o every five years thereafter;
o as necessary during operations to determine the stability of the cavern and the overburden if the salt roof thickness and cavern geometry indicate that the stability of the cavern or overburden is at risk; and,
o before plugging and abandoning the well if a sonar survey has not been run in the
past five (5) years.
The Company will also monitor the thickness for each storage cavern roof using a combination of the sonar survey data, gamma ray log and/or a density log. The cavern roof thickness will be no less than 200 feet between the final cemented casing shoe and cavern roof in accordance permit requirements or meet the geomechanical recommendation of a thickness that is equivalent to a 2:1
pillar to cavern diameter measurement. This monitoring will be scheduled at the same time as the
required mechanical integrity testing to include:
 every five years after the start of operations; and,
 as necessary if the Company or DWQ has concerns of cavern integrity.
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Hydrogen Cavern Field Operating Plan 3-4 February 2025
The Company may elect to monitor cavern capacity and geometry with an alternative method as allowed by regulation. In this event, the Company will submit the following information for DWQ’s consideration:
 a description of the proposed method and the theory for its operation;
 a description of the storage well and cavern conditions under which the log can be used;
 the procedure for interpreting the survey results; and,
 an assessment of the capacity and stability of the cavern upon completion of the survey.
3.2.1.4 Hydrogen Inventory Verification
Routine inventory verification will be conducted by the Company as a secondary risk mitigation
measure to both prevent an overfilling event from occurring and/or detect an inventory loss that
could indicate a mechanical integrity issue with the storage cavern. Inventory verification will be completed using a combination of industry accepted methods that will be applied based on operational applicability:
 monitoring of gas injections and withdrawals;
 indirect/model-based monitoring method using temperature and pressures measurements
at the wellhead; and,
 direct/real-time measurement monitoring method using temperature and pressure using a
fiber optic system installed within the cavern.
The monitoring of gas injections and withdrawals and indirect/model-based monitoring of temperature and pressure measurements at the wellhead is the current industry standard for
monitoring cavern inventory. The direct/real-time measurement method using downhole
equipment is an alternative method that is also used by the industry but is often paired with the other standard methods to mitigate any equipment reliability and maintenance challenges that are known to be frequently encountered when employing downhole systems. The use of all three monitoring methods will therefore provide redundancy and optionality to meet the Class III and V
Permit and other regulatory monitoring requirements without risking unnecessary operational
shutdowns. The Company will also maintain an open line of communication with the DWQ about the performance of the downhole fiber optic system to be able to adjust the use and configuration of the equipment as necessary.
Using the indirect/model-based method, the stored gas volume for each cavern will be initially
calculated using the temperature profile, physical cavern volume, and physical properties of the gas. The temperature profile for each cavern will be based on the data from the continuous cavern pressure and temperature log and core data collected at the time of cavern well drilling. This is the same profile that is used for geomechancial models run by RESPEC to develop the design
operating parameters. The physical cavern volume will be based on the initial sonar survey
completed just prior to operational start up. The total gas volume stored is then calculated using rigorous equations of state that have been determined empirically for the specific gas that is being stored. The gas properties data, which are used in these equations of state are obtained from an industry database. It is anticipated that the Peng-Robinson equation of state will be used or another
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Hydrogen Cavern Field Operating Plan 3-5 February 2025
widely-accepted equations of state that is applicable to the specific facility storage operations. The Peng-Robinson equation of state has the basic form: `p = (R*T)/(V_m - b) - (a*alpha)/ (V_m^2 + 2 * b * V_m - b^2) ` to describe the state of the gas under given conditions, relating pressure,
temperature and volume of the constituent matter. A detailed methodology for inventory
verification and a proposed quarterly report is included in Appendix D. The measurements derived from the indirect/model-based method and injection and withdrawal monitoring will be verified periodically using measurements of the actual pressure and temperature
conditions within the cavern. These measurements will be collected using a fiber optic interrogator
installed along the length of the hanging string with multiple gauges to obtain pressure and temperature profiles at various intervals. This information will be converted in pressure and temperature values that can then be used to verify the cavern inventory against the injection and withdrawal measurements monitored at the wellhead. Appendix D provides the inventory
verification methodology in greater detail as well as the proposed fiber optic monitoring system.

3.2.1.5 Off-Schedule Monitoring Activities
The Company may also conduct periodic monitoring activities that fall outside of the monitoring
required by the permits and regulations. Notice of any additional monitoring activity will be given
to DWQ 48 hours prior to the start of the monitoring.
 The notice will describe measures to ensure the protection of public health, safety, and the environment.
 The measures will include the use of appropriate blowout prevention equipment,
depressuring of well as needed, and spill containment material.
Results of any such monitoring activity will be reported to the DWQ as described in Section 4 below.
3.2.1.6 Solution Mining Activities
In the event solution mining is conducted during operations, the Company will monitor salinity and temperature of the injected fluid daily as stipulated in the Class III UIC Permit and outlined
in the approved MMRP. This monitoring will be completed as follows:
 Specific gravity and temperature will be measured using calibrated hydrometers and thermometers;
 Hydrometers will be calibrated and maintained in accordance with American Society for Testing and Materials (ASTM) standard A126-05a; and,
 Thermometers will be calibrated and maintained in accordance with ASTM E77-07.
3.2.2 Testing and Inspection
3.2.2.1 Mechanical Integrity Testing
During storage operations, the Company will complete routine Mechanical Integrity Testing (MIT) of all storage cavern and cavern well systems in accordance with 40 CFR 146.33 and 40 CFR 146.8. MITs are completed to ensure no significant leaks and no significant fluid movement into
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Hydrogen Cavern Field Operating Plan 3-6 February 2025
an underground source of drinking water through vertical channels adjacent to the injection well bore. Per the regulation an injection well will be deemed to have has mechanical integrity if:
 There is no significant leak in the casing, tubing or packer; and,
 There is no significant fluid movement into an underground source of drinking
water through vertical channels adjacent to the injection well bore. The Company will conduct the required MITs periodically at the following times:
 after the solution mining of a storage cavern is completed and the cavern is ready to be placed into operations;
 every five years after a cavern has been placed into operations;
 after a cavern has a workover that involves physical changes to any cemented casing suspended string; and,
 before a cavern and cavern well system is plugged with the intention of abandonment, unless and MIT has been performed in the last five (5) years.
To evaluate the absence of significant leaks, the Company will complete MIT requirements in accordance with the following methods listed under the regulations:
 Following an initial pressure test, monitoring of the tubing-casing annulus pressure with
sufficient frequency to be representative, while maintaining an annulus pressure different
from atmospheric pressure measured at the surface; and
 Pressure test with liquid or gas; or
 Records of monitoring showing the absence of significant changes in the relationship
between injection pressure and injection flow rate for the following Class II enhanced
recovery wells:
To evaluate the absence of significant fluid movement, the Company will also complete the following tests listed under the regulations:
 The results of a temperature or noise log; or
 For Class III wells where the nature of the casing precludes the use of temperature or noise
logs, cementing records demonstrating the presence of adequate cement to prevent such
migration; and,
 For Class III wells where the agency has elected to rely on cementing records to
demonstrate the absence of significant fluid movement, the Company has designed the
monitoring program in accordance with CFR 146.33(b) to verify the absence of
significant fluid movement.
It should be noted that the initial MIT completed prior to placing the storage cavern will include a
pressure test using the nitrogen/brine interface test method and brine hydrostatic test. This test is an industry standard test designed to evaluate the internal (cavern well) mechanical integrity and/or
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Hydrogen Cavern Field Operating Plan 3-7 February 2025
the external (storage cavern) mechanical integrity at the start-up of operations. The procedures for the MIT consist of filling the cavern with water or brine and then injecting nitrogen into the well and establishing an interface at a depth appropriate for either a cavern well or storage cavern test.
The nitrogen test pressure should be equal to the MAOP gradient based on the casing seat. The
interface, temperature and pressure data are used to calculate the pre-test and post-test nitrogen volumes. Comparison of the pre-test and post-test nitrogen volumes and movement of the nitrogen/brine interface are then used to evaluate the well/cavern integrity.
After the initial MIT is completed, the pressure test methods will alternate every five years between
a gas filled method and brine/nitrogen interface method as appropriate to reduce the need for
unnecessary operational shut-downs while ensure cavern integrity is maintained. Further, all MITs at the Facility will be conducted by an industry expert with experience in conducting this type of testing due to the complexity of the test and associated safety requirements. The test contractor will be required to have knowledge of:
 the pressure rating of the well and wellhead components;
 the use of dead-weight tests or calibrated data loggers to verify brine and nitrogen pressure;
 methods to track the volume of nitrogen injected before and during the test;
 differential pressure monitoring to prevent collapse of the tubing; and,
 a working knowledge of other procedural tasks that ensure a viable and safe test.
In accordance with the 40 CFR 146.8, the Company can also elect to use an alternative mechanical integrity test method by submitting the following information for DWQ’s consideration:
 description of the test method and the theory of operation, including the test sensitivities, a justification for the test parameters, and the pass and fail criteria for the test;
 description of the cavern well and storage cavern conditions under which the test can be
conducted; and,
 a procedure for interpreting and reporting the test results.
The Company also acknowledges that the agency can require additional or alternative tests if the results presented under the requirements of 40 CFR 146.8(e) are not satisfactory to demonstrate that there is no movement of fluid into or between USDWs. Further, in the event an MIT is
determined unsuccessful, the storage cavern that did not pass the MIT will be taken out of storage service until an evaluation can be completed.
3.2.2.2 Casing Evaluation
The Company will complete a casing evaluation of all storage cavern and cavern well systems at 10-year intervals in conjunction with the required MIT schedule. The methods that will be used include magnetic flux, ultrasonic imaging, or a multi-finger caliper. The evaluation will
be to identify the following conditions:
o the presence of any metal loss due to either of the following:
o internal or external corrosion and internal wear; o the degree of penetration of the corrosion or the casing defect; and,
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Hydrogen Cavern Field Operating Plan 3-8 February 2025
o the circumferential extent of the corrosion or the casing defect.
The Company can also elect to use an alternative casing evaluation method by submitting the following information for DWQ’s consideration:
 a description of the logging method, including the theory of operation and the cavern
well conditions suitable for log use;
 specifications for the logging tool, including tool dimensions, maximum temperature and pressure rating, recommended logging speed, approximate image resolution, and hole size range;
 The Company will describe the capabilities of the log for determining the conditions
listed above.
3.2.3 Hydrogen Embrittlement Management
The Company is aware that hydrogen embrittlement of certain cavern well system components and the hydrogen pipeline delivery system have the potential to occur from the interaction of the component materials with the stored hydrogen. Given that hydrogen embrittlement is most
commonly a result of poor welding practices and materials selection, the Company developed an engineering design that contains several key criteria and industry practices to mitigate potential risks. The main design element that has been incorporated includes the selection of hydrogen-resistant, low-carbon steel and stainless steel, and the installation of a cathodic protection system. Minimizing carbon in the steel chemistry results in material that is less susceptible to the impacts
of hydrogen. In addition, welding procedures have been developed that involve weld pre-heating and post-heating to facilitate carbon dispersing evenly thereby preventing a harmful concentration of carbon in and around the weld. Other design elements include reducing the range of operating pressures and the presence of chlorides, solids, and water in any withdrawn hydrogen gas. At this time, the Company believes that the incorporation of these design elements and operating
procedures will sufficiently mitigate embrittlement risks but will incorporate any new industry standards that are established during operations.

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Hydrogen Cavern Field Operating Plan 3-9 February 2025

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Hydrogen Cavern Field Operating Plan 4-1 February 2025
Section 4 Agency Reporting and Notification
The Company will complete reporting and notifications to the DWQ in accordance with the
requirements of the Class III and V UIC Permits per 40 CFR 146.33.
4.1 Storage Cavern Field
 An annual report will be submitted to the DWQ on or before June 1 of each year for the preceding period of April 1 through March 31. The annual report will include:
o description of any incident of uncontrolled or unanticipated hydrogen loss;
o well number and date of any logs or sonar surveys conducted;
o estimated storage capacity for all unplugged caverns;
o list of any caverns being enlarged under the Class III UIC permit;
o list of the volume of hydrogen injected and withdrawn for each well; and,
o list, by well number, of the maximum and minimum hydrogen storage pressures encountered during the report year with the average and standard deviation noted.
 The Company will notify DWQ at least five (5) days before conducting any MIT.
 The Company will follow the notification requirements in the facility’s Emergency, Health and Safety Plan and provide oral notification to DWQ within two hours and submit written notification to DWQ within one week if any of the following events occurs:
o over-pressuring or the overfilling of a storage cavern;
o loss of integrity of a cavern well or storage cavern;
o release of brine, hydrogen, or any other chemical parameter that poses a threat to public health, safety, or the environment;
o any uncontrolled or unanticipated loss of hydrogen or brine that is detectable by any monitoring or testing;
o any other condition that could endanger underground drinking water source, public health, safety, or the environment;
o the establishment of communication between storage caverns;
o the triggering of critical alarms verifying that safety requirements have been exceeded; and/or,
o any equipment malfunction or failure that could result in potential harm to public health, safety, or the environment.
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Hydrogen Cavern Field Operating Plan 4-2 February 2025
 A summary of any monitoring or testing activities conducted on components of the storage cavern field will be submitted to DWQ within 45 days after completing the test. The
summary will include:
o a chronology of the test;
o copies of all logs;
o storage well completion information;
o pressure readings;
o volume measurements; and,
o an explanation of the test results.
 Subsidence monitoring survey results, including certified and stamped field notes, will be reported to the DWQ on a quarterly moving to annual basis. The report will be submitted within 30 days after the completion of the annual elevation survey.
o In the event a surface elevation change is detected that is in excess of 0.50 foot since
the previous survey, DWQ, SITLA and Millard County will be notified within 24 hours.
4.2 Storage Cavern and Cavern Well System
 An inventory verification report will also be submitted on a monthly basis the first year of operations and then quarterly thereafter. The report will track any inventory that is injected and withdrawn to confirm an inventory balance. Appendix D provides the
methodology and the inventory report form. If a discrepancy over 5% is identified by the inventory verification, an internal evaluation will be initiated to determine the cause. If a discrepancy of 8% or more larger is identified by the inventory verification, an internal evaluation will be initiated to determine the cause and the discrepancy will be reported to DWQ within 30 days.
 An annual summary report will be submitted to DWQ of any cavern enlargement under the DWQ Class III UIC permit completed during operations that will include the
estimated growth and tabulation of the pillar thickness (P) between adjacent caverns
and between caverns and the permit boundary areas at 200-foot depth intervals beginning at the depth of the last cemented casing.
 If an individual cavern is no longer eligible for enlargement under the Class III UIC Permit, the Company will submit a notice to DWQ within 30 days if any method of
cavern monitoring indicates that cavern has experienced a 5% growth in the cavern
volume after the planned size has been reached (either 5.5 mmbbls in size or a size that maintains the minimum required pillar).
 A summary report and the results of any storage cavern monitoring activity will be submitted to DWQ within 30 days after completion of the monitoring activity. A casing
evaluation report will be submitted to DWQ per the following requirements:
o 10 years after the cavern well is placed into operation and every five years thereafter; o after any workover involving the cemented casing; and,
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Hydrogen Cavern Field Operating Plan 4-3 February 2025
o if a determination is made by DWQ that the integrity of the suspended string casing could be adversely affected by any naturally occurring condition or man-made
activity.
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Hydrogen Cavern Field Operating Plan 4-4 February 2025

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Hydrogen Cavern Field Operating Plan 5-1 February 2025
Section 5 Records Retention
The Company will maintain records associated with the operations of the storage cavern field and
individual storage caverns and cavern well systems as outlined below:
 A period of five years, for:
o The maximum and minimum operating pressures for each well; and,
o The periodic inspections conducted by DWQ that will be quarterly moving to annual during operations.
 The life of the cavern well, for:
o The casing records for each well;
o The cementing records for each well;
o The workover records;
o The water or brine injection records for each well;
o Monitoring information, including calibration and maintenance records; and,
o Continuous monitoring data.
 The life of the facility, for:
o All logging events;
o All mechanical integrity tests and other testing;
o All groundwater monitoring data; and,
o All correspondence relating to the operating plan, including electronic mail.
 Surface elevation surveys will be maintained and retained for the life of facility plus 10 years after the facility’s closure.
 In the event of new ownership of the facility, all required facility records, reports, and
documents must be transferred to the new owner.
The Company will conduct an annual inspection of facility records to ensure that the required records are being properly maintained. These records will be maintained at the facility and the records will be available to DWQ upon request.

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Hydrogen Cavern Field Operating Plan 5-2 February 2025

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Appendix A
Storage Cavern Wellhead Summary Tables
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Typical Wellhead Pressures for Hydrogen Storage
Operation Casing (inches) Fluid Pressure at Casing Shoe
(psi)
H2 Stored (bcf) Surface Pressure (psi)
Hydrogen Maximum Inventory
10-3/4” x 7” Hydrogen 3,106 2.44 3,083
Hydrogen Minimum Inventory
10-3/4” x 7” Hydrogen 1,281 1.11 1,270
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Appendix B
Inventory Verification Methodology
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Hydrogen Cavern Integrity and Inventory Verification
Indirect/Model-Based Methodology

I. Introduction

WSP USA Inc. (WSP) is the leading engineering services firm for underground storage cavern
development in North America. WSP (FKA, PB Energy Storage Services and PB-KBB) also
provides cavern testing and maintenance services for the majority of, North American storage
operators and is very familiar with the methods used for verification of cavern integrity and storage
inventory. The following methodologies have been adopted by various state regulators, e.g. Texas
Railroad Commission, and have been adopted as an API recommended practice (see API RP
1170). When directed to be used per the field operating plan, detailed procedures will be prepared
and approved by the operations team and management, prior to implementing.

II. Cavern Integrity Verification

Prior to placing a newly developed salt cavern into service, and subsequently at specified time
intervals thereafter, a mechanical integrity test (MIT) is performed. During a mechanical integrity
test, the cavern is pressured to an authorized level just slightly above its maximum allowable
operating pressure (MAOP) and is monitored for a specific period of time. The MIT is performed
in one of two commonly followed methods, noted below.

1. Brine-Filled Cavern
Upon completion of cavern leaching or after a well workover, the cavern is pressured with
nitrogen in the space above the brine and the position of the brine-nitrogen gas interface is
monitored for movement using a wireline log. The starting quantity of nitrogen is
calculated and compared with the calculated amount remaining toward end of the test.

The difference between the beginning and ending nitrogen quantities is the calculated leak
rate (CLR) which, is compared with a predetermined amount, i.e. Minimum Detectable
Leak Rate (MDLR). If CLR is less than MDLR, the cavern is considered as having
satisfactory integrity.

2. Gas-Filled Cavern
When a gas storage cavern does not contain brine such as, after it has been in operation, it
is tested by pressuring the cavern to the MAOP then, running an initial pressure and
temperature log. After 72 hours a second pressure and temperature log are run. The gas
volumes from the initial and second logging runs are calculated and the difference
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determined. If the calculated difference does not exceed a predetermined quantity, then
the cavern is deemed to have sufficient integrity for gas storage.

III. Cavern Inventory Verification/Monitoring

Cavern inventory verification is a holistic set of ongoing processes that occur at different operating
levels and differing frequencies, depending upon the process. Those frequencies are dictated by
the field operating plan. They start with the previously mentioned MIT to verify containment
integrity of the cavern system. All of these processes are cross-checked against each other to
enhance cavern inventory verification and provide confidence of cavern integrity. Significant
variances between inventories based upon different methods shall be investigated.

The gas contained in the cavern is based on the volume of the cavern, the composition and physical
properties of the stored gas, and the pressure and temperature of the gas in the cavern. After
completion of the cavern leaching process, the cavern volume is first gauged using an ultrasonic
imaging tool, i.e. a “sonar” and, as brine is displaced from the cavern upon the initial gas fill, the
volume of displaced brine is determined. The sonar volume is less precise than the displaced
volume, however, the sonar provides a useful three-dimensional rendering of the cavern. This
three-dimensional rendering allows for comparison with future sonar surveys to determine changes
in cavern shape thereby validating modelled creep estimates which in turn benchmarks the cavern
volume that is used for inventory calculations. It also that may indicate potential integrity
problems prior to them happening. The techniques for inventory verification and monitoring are
given below.

1. Physical (Measured) Parameters Method
The stored gas volume is initially calculated with data from a cavern pressure and
temperature log, the physical cavern volume (sonar/measured displaced brine volume), and
physical properties of the gas. The total gas volume stored is calculated using rigorous
equations of state that have been determined empirically for the specific gas that is being
stored. The gas properties data, which are used in these equations of state are obtained from
an industry database (see: Design Institute of Physical Properties, www.aiche.org/dippr).
It is anticipated that the Peng-Robinson equation of state will be used or another widely-
accepted equations of state that is applicable to the specific facility storage operations. The
Peng-Robinson equation of state has the basic form: `p = (R*T)/(V_m - b) - (a*alpha)/
(V_m^2 + 2 * b * V_m - b^2) ` to describe the state of the gas under given conditions,
relating pressure, temperature and volume of the constituent matter.

This method can also be augmented, as opportunities present themselves, by the use of a
calculation technique known as a two-point analysis method. This technique benchmarks
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against metered quantities of gas over a certain time period, enhancing confidence in
inventory results.

Table 1 lists the measured parameters including data, which is maintained in the facility
data historian and available for audit.
Table 1. Cavern Inventory Management – Measured Parameters
Parameter Measurement Method(s) Typical Units and/or Data Available for Audit Notes
1. Cavern Physical Dimensions/Volume Ultrasound (Sonar) & Volume of Brine Displaced Cavern volume as established by sonar is calculated using software that is specific to the sonar imaging tool. The sonar data is converted into API barrels, which is then used as a basis for determining cavern inventory. The metered brine volume (API barrels and/or US Gallons) is recorded by the facility data historian and is also a basis for inventory calculation. The cavern volume and hydrogen inventory are maintained in the data historian and is available for audit.
The cavern volume is determined with an ultrasonic imaging tool and the amount of brine displaced during the initial cavern fill provides the volume occupied by the hydrogen. The sonar is run periodically to determine changes in physical cavern volume. The brine displaced from the cavern during initial fill and after the cavern is de-watered is measured by a magnetic or other type of flow meter.
2. Injected Hydrogen Volume Multi-Path Ultrasonic or Other Type of Flow Meter The flow of hydrogen into or out of the cavern is measured and recorded by the facility data historian. The volumetric units may be reported as millions of standard cubic feet (MMSCF). This information is available for audit.
The meter is installed in the flow line that connects to the wellhead. The meter is designed to measure flow going into or coming out of the storage well (bi-directional flow meter). The metering takes into account pressure and temperature of the flowing gas to ensure accurate flow measurement.
3. Wellhead Pressure Pressure Transmitter Located on the Flow Line near the Wellhead. A second pressure transmitter will be placed between a wellhead wing valve and ESD valve to detect pressure when the storage cavern is shut in.
The pressure is recorded in pounds per square inch gauge, i.e. psig. The pressure is continuously monitored and is recorded at a predetermined interval (usually once per minute) in the facility data historian. The recorded pressure data is maintained in the data historian and is available for audit.
Pressure measurement is used to calculate cavern inventory independently of the flow meter. The pressure measurement may also be used in conjunction with certain types of flow meters to compute hydrogen flow.
4. Wellhead Temperature Temperature Transmitter Located on the Flow Line near the Wellhead.
The temperature is recorded in degrees Fahrenheit, i.e. oF. The temperature is continuously monitored and is recorded at a predetermined interval (usually once per minute) in the facility data historian. The recorded temperature data is maintained in the data historian and is available for audit.
Temperature measurement is used to calculate cavern inventory independently of the flow meter. The temperature measurement may also be used in conjunction with certain types of flow meters to compute hydrogen flow. Temperature is most accurate when hydrogen is flowing. A wellhead pressure and flowing (not static) wellhead temperature may then be used as inputs to the gas correlation (Peng-Robinson) to
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calculate the gas inventory at any given point.
5. Cavern Hydrogen Flows Use of Flow Meter The flow may be presented in millions of standard cubic feet per day, i.e. MMscfd. The flow data are recorded by the facility data historian and are available for audit.
Cumulative volumes injected and withdrawn from storage are determined through measurement with the flow meter.

2. Gas Accounting Method
Gas volumes injected to and withdrawn from the cavern are continuously metered at the
cavern wellhead and are used for calculating the cavern inventory status in real time. The
types of meters that may be used include, ultrasonic, turbine or orifice-type meters, some
of which require periodic calibration to assure measurement accuracy. The incoming or
outgoing gas temperatures are factored into the flow measurement for achieving the proper
level of accuracy, and all data is stored in the plant historian, accessible for audit purposes.

Due to small inaccuracies in measurement, the cumulative measurement error may add up
and/or cancel out over time and may or may not result in an increasing discrepancy between
the actual and calculated cavern inventory over time. The influence of salt creep, whereby
the volume of the cavern decreases over a period of time, will to a small degree, impact
cavern inventory measurement. The direct logging of the gas pressure and temperature in
the cavern, as well as a sonar3 volume calculation is performed periodically to resolve any
discrepancy.

Table 2, below, is an example of the Gas Accounting Method where, a monthly report
form is presented. The form shows the beginning cavern inventory, which is the ending
cavern inventory of the preceding month (or calculated initial inventory when the cavern
is first placed in operation). The daily metered injection and withdrawal volumes are added
to (injections) and subtracted from (withdrawals) the beginning inventory through the end
of the month. Daily static wellhead pressures readings are shown and are adjusted to mid-
cavern pressures to allow for a volume calculation that is used to compare with metered
volumes in order to detect possible irregularities. Flowing wellhead temperatures during
injection and withdrawal are also used in the gas volume calculations and adjusted to
cavern conditions. The metered gas volumes, wellhead pressures and temperatures, and
inventory calculations are recorded and maintained by the facility data historian and are
available for audit.

3 Periodic sonar surveys detect changes in cavern volume, which may indicate cavern salt creep.
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3. Material Balance/Hysteresis Curves
For Hysteresis Curves, the mid-cavern pressure (wellhead pressure plus the gas column
pressure to mid-cavern) versus gas inventory is plotted. The plot shows the cavern pressure
– inventory relationship. Metered gas volume deviations from the plot may indicate an
issue either with containment or gas measurement error. The daily static wellhead pressure
readings (corrected to mid-cavern pressure) and corresponding inventory calculations
based on metered gas injections and withdrawals (see Gas Accounting Method, above) are
compared with pressure versus inventory curve.

Figure 1 is presented as an example and shows the relationship of wellhead pressure
(corrected to reflect mid-cavern pressure) and cavern inventory. Metered hydrogen
injection and withdrawal volumes are added or subtracted, respectively, from the starting
cavern inventory and the corresponding measured wellhead pressure (corrected to mid-
cavern pressure) is plotted along with the material balance/hysteresis curve. Significant
deviations (trends) between calculated and metered cavern inventories may require further
analysis to determine if there is a cavern containment problem or measurement error.

As with the Gas Accounting Method, the cavern inventory will be re-verified, periodically
and this measurement technique fine-tuned with a sonar survey and cavern pressure and
temperature log.

Cavern/Storage Well No.
Reporting Month/Year Day Day …..Day
Sonar Volume 1 2 30
Beginning Wellhead Pressure
Beginning Wellhead Temperature (Flowing)
Beginning Inventory (Calculated)
Beginning Inventory (Metered)
Withdrawals
Injections
Ending Inventory (Metered)
Ending Wellhead Pressure
Ending Wellhead Temperature (Flowing)
Ending Inventory (Calculated)
Note: Calculated Beginning Inventory is calculated from sonar volume and wellhead pressure and temperature, adjusted to reflect cavern conditions.
Beginning Inventory (Metered) is the ending metered inventory from the previous month.
___._ MMSCF
____ psig
___oF
___._ MMSCF
#
__,____,____BBLs
___._ MMSCF
___._ MMSCF
___._MMSCF
TABLE 2. Gas Accounting Method
MM/YYYY
____ psig
___oF
___._MMSCF
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Figure 1

4. Other (Thermal Simulation)
Another method that may be performed should more investigation be required, is thermal
simulation using SCTS® (Salt Cavern Thermal Simulator) or other similar methods.
SCTS® considers salt properties; cavern geometry, dimensions and depth; well
configuration; gas properties; operating pressures and temperatures; and, frequency,
duration, and flow rates into and out of the cavern. The accuracy of SCTS® is as good as
the data that is input to the program.

SCTS® using, the latest cavern sonar survey and pressure and temperature logs and
considering the past injection and withdrawal volumes and durations, can produce a
reasonably accurate depiction of how the cavern storage pressures and temperatures should
behave over time. The simulation results may be compared with past operations to identify
possible irregularities, if any, and provide clues as to possible underlying causes.

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Appendix C
Subsidence Monitoring Plan
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Subsidence
Monitoring Plan
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Subsidence Monitoring Plan

Advanced Clean Energy Storage I,
LLC
Hydrogen Production and
Storage Facility
Delta, Utah

February 2025
Prepared by
Advanced Clean Energy Storage I, LLC 3165 E. Millrock Dr., Suite 330 Holladay, Utah 84121 Tel [phone] Fax [phone]
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Subsidence Monitoring Plan i February 2025
Table of Contents
Section 1 Introduction................................................................................................................................... 1-1
1.1 Purpose of the Plan ............................................................................................. 1-1
1.2 Facility Location ................................................................................................. 1-1
1.3 Facility Description............................................................................................. 1-2
1.4 Storage Cavern Field Description ....................................................................... 1-2
1.5 Potential Subsidence ........................................................................................... 1-3
Section 2 Subsidence Monitoring System .................................................................................................. 2-1
2.1 Subsidence Monitoring Network ........................................................................ 2-1
Section 3 Monitoring Procedures ................................................................................................................ 3-1
3.1 Monitoring Methods ........................................................................................... 3-1
3.2 Monitoring Frequency ........................................................................................ 3-1
Section 4 Agency Reporting and Notification............................................................................................. 4-1
4.1 Reporting ............................................................................................................ 4-1
4.2 Notification ......................................................................................................... 4-1
Section 5 Record Retention .......................................................................................................................... 5-1
5.1 Records ............................................................................................................... 5-1

Figures
Figure 1. Vicinity Map ................................................................................................................ 1-1
Figure 2. Subsidence Monument Network ................................................................................. 2-3

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Subsidence Monitoring Plan 1-1 February 2025
Section 1 Introduction
1.1 Purpose of the Plan
The purpose of this Subsidence Monitoring Plan (Plan) is to document regulatory compliance
procedures for the monitoring of potential ground subsidence in the vicinity of the Storage Cavern Field at the Advanced Clean Energy Storage I, LLC (Company) Hydrogen Production and Storage Facility (Facility). Specifically, the Plan outlines the subsidence monument network, monitoring methods and frequency, agency reporting and notification requirements, and record retention policies.
1.2 Facility Location
The Facility is located approximately eight miles north of Delta in Millard County, Utah, on lands
leased from the School and Institutional Trust Lands Administration (SITLA). As shown on Figure 1, the Facility is situated west of Highway 6 near the intersection of Jones Road and Brush Wellman Road/SR-174.
Figure 1. Vicinity Map
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Subsidence Monitoring Plan 1-2 February 2025

1.3 Facility Description
The Facility is comprised of three main components: a Storage Cavern Field, two brine evaporation ponds, and an electrolyzer facility to produce hydrogen with an associated evaporation pond. The Facility will also contain utilities interconnecting those components, including brine, water, hydrogen gas pumping and pipeline systems, power and communications lines, and a smaller evaporation pond. As stated, the monitoring procedures in this Plan pertain only to the monitoring
of potential subsidence in relation to the Storage Cavern Field.
1.4 Storage Cavern Field Description
The Storage Cavern Field currently includes two storage caverns that are each up to 5.5 million barrels (mmbbls) in capacity, with approximate 220 to 350 foot cavern diameters and approximate 1,750 foot cavern heights. These caverns will be constructed in a salt formation located approximately 3,000 feet below ground surface (bgs) using standard solution mining technology.
While cavern depths within the salt formation are dependent upon the individual cavern locations
relative to the below ground elevation of the top of the salt, the tops of caverns will likely range in depth between 3,500 and 4,100 feet bgs and the base of caverns will range in depth between 4,500 and 5,700 feet bgs. The timing of construction of each cavern within the Storage Cavern Field will be dependent upon market demand.
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Subsidence Monitoring Plan 1-3 February 2025
Figure 2 depicts the Subsidence Monument Network and the major Facility components at full-build out, including the location of the Storage Cavern Field along with the approximate locations
and numbers of the first two planned storage caverns and cavern wells, Hydrogen Cavern Well 1
(CW-2) and Hydrogen Cavern Well 2 (CW-23). The Company plans to develop and operate multiple storage caverns within the Storage Cavern Field.
1.5 Potential Subsidence
Subsidence, or the downward change in surface elevation, in association with solution mined storage caverns is directly related to cavern “creep”. Cavern creep, or closure, is a term used to describe the process by which cavern walls close shut over time due to the malleable or “self
healing” property of salt at depth and pressure. Subsidence above a solution mined storage cavern is a direct result of cavern creep. The subsidence is caused by the change in the below ground elevation of the salt formation as it creeps shut to fill in the cavern void.
The rate at which this type of subsidence occurs is very slow, typically over a period of months or years. Surface manifestation of subsidence tends to be minimal and restricted to the area directly
above, or in immediate proximity to, the subsurface cavern. There are instances, however, where the total affected area at the surface is greater than the immediate subsurface cavern diameter. Consequently, Company will use a radial network of subsidence monuments that extend between 5,000 and 7,000 feet away from the Storage Cavern Field. Company has committed to use this network to monitor for potential surface subsidence associated with the solution mining and
operation of storage caverns.

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Subsidence Monitoring Plan 2-1 February 2025
Section 2 Subsidence Monitoring System
2.1 Subsidence Monitoring Network
The Subsidence Monitoring Network for the Facility will be comprised of 15 new and existing monitoring and stable reference monuments: three new monitoring monuments installed by the Company, 11 subsidence monuments from an existing radial network and one existing stable reference monument. The radial network and stable reference monument were previously installed by Sawtooth Caverns, LLC (Sawtooth) for the purpose of monitoring potential subsidence
associated with an adjacent storage caverns facility. Company has entered into a cooperative agreement with Sawtooth to allow it to use the existing network of monitoring points and monuments.
Figure 2 depicts the main Facility components and the Subsidence Monument Network at final build-out. The density and distribution of the subsidence monuments are based on: the surface and
subsurface geology of the planned Storage Cavern Field; the individual storage cavern locations, sizes and calculated creep rates; and the potential radial influence of subsidence at the surface. As shown on Figure 2, the Subsidence Monument Network monitoring monuments will include:
Existing Deep Surface Monuments
 one central subsidence monument installed in the center of the Storage Cavern Field;
 two subsidence monuments installed at 1,500’ radius;
 three subsidence monuments installed at 2,500’ radius;
 three subsidence monuments installed at 5,000’ radius;
 two observation wellhead subsidence monuments (DA-1 at 6,000’ and DA-2 at 7,000’);
Existing Stable Reference Points
 one existing stable reference point monument at 6,000’;
New Deep Surface Monuments
 one subsidence monument installed at 1,500’ radius outside the Sawtooth storage cavern field fence line;
New Bedrock Well Monuments
 two storage cavern wellhead subsidence monuments (CW-2 and CW-23);

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Subsidence Monitoring Plan 2-2 February 2025
Of the 15 monitoring monuments, 12 are local deep surface subsidence monuments (all but CW-
2, CW-23, and the main control point monument) installed to provide representative geospatial coverage across the area of interest. These local monuments are based on a central monument (see Figure 2) situated near the center of the proposed extent of the Storage Cavern Field. From this central monument, nine additional deep surface local monuments are situated at radial intervals of 1,500 feet; 2,500 feet; and 5,000 feet. In addition to this array of local monuments, two subsidence
monuments will function as bedrock monuments, storage cavern wells CW-2 and CW-23, which extend into the bedrock. As the Facility is expanded, Company will install new monuments on each additional cavern and water well when constructed and may add monuments to the radial network if necessary.
There is one stable reference point that is part of the subsidence monument network: This is an
existing main control point monument located approximately 6,000 feet from the center of the Storage Cavern Field. This point will serve through time as the stable reference point for the entire subsidence monitoring network as the monument is located beyond the potentially affected surface area.
The horizontal position of all monuments was established by GPS survey and defined in both the
State Plane Coordinate System and the Company’s local coordinate system of northings and eastings on an X and Y coordinate based on true north. The main control point monument is located at a horizontal distance of approximately 6,000’ from the center of the Storage Cavern Field. This monument was installed June 1, 2010, to create a stable and permanent benchmark and control point for all Magnum projects. It is a stainless-steel rod driven to refusal, isolated from surface
frost by a greased sleeve, and protected within a concrete monument box, and was constructed to the Class A Rod Mark standard in accordance with guidance promulgated by the United States National Oceanic and Atmospheric Administration (NOAA).

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Subsidence Monitoring Plan 2-3 February 2025
Figure 2. Subsidence Monument Network

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Subsidence Monitoring Plan 3-1 February 2025
Section 3 Monitoring Procedures
3.1 Monitoring Methods
Company will complete precise elevation or “level” surveys of the Storage Cavern Field and potentially affected area to monitor for subsidence at the Storage Cavern Field. Level surveys will
be completed under the direct supervision of a licensed surveyor . Surveys will be capable of
detecting elevation changes to within 0.01 foot. Surveys will include points taken at and between the monuments in the subsidence monitoring network and points taken across and beyond the potentially affected area. Surveys will be completed according to best practices including:
 perform peg test at the beginning of each survey to verify that the instrument is in good
adjustment; additional tests should be performed whenever the instrument is suspected to have been put out-of adjustment by mishandling;
 standard field note recording techniques will be followed including recording of temperature and weather conditions;
 balance backsight and foresight distances within the tolerances specified by the accuracy
requirement;
 monuments have been distributed so that no turning points are needed in the execution of the field leveling (if turning points are needed to complete the level survey, either metal turning pins or turning plates should be used to minimize the errors caused by rod displacement);
 instruments will be shaded from direct sunlight for second-order leveling; and
 closure check will be performed at the completion of each loop or line segment on the field (if the closure exceeds tolerance the loop or line should be rerun).
3.2 Monitoring Frequency
As described above, most of the monuments in the subsidence monitoring network are currently in place and the remaining monuments will be installed during Facility construction. Before
commencement of solution mining for the first hydrogen cavern, a baseline elevation survey will
be completed. Subsidence monitoring will be initiated the first month after storage operations commence. During the first year of storage operations, monitoring events will be completed on a quarterly basis. After the first year of operations, monitoring events will be completed on an annual basis. If monitoring results indicate subsidence in excess of the reportable amount described in
Section 4, Company will consult with the Division of Water Quality (DWQ) to determine if a
change in monitoring frequency is necessary.
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Subsidence Monitoring Plan 3-2 February 2025

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Subsidence Monitoring Plan 4-1 February 2025
Section 4 Agency Reporting and Notification
4.1 Reporting
Company will prepare and file an annual report with DWQ and Millard County. The report will be submitted by March 1 of each year after storage operations has commenced. The report will
include the certified and stamped survey results and a summary that identifies any subsidence that
has occurred since the last monitoring event and a cumulative subsidence total since the initiation of storage operations.
4.2 Notification
Company will report surface elevation changes in excess of 0.5 feet within 24 hours of the monitoring event to DWQ and Millard County.

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Subsidence Monitoring Plan 4-2 February 2025

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Seismic Monitoring Plan 5-1 February 2025
Section 5 Record Retention
5.1 Records
Company will retain copies at the Facility of this Plan, the initial baseline survey, any annual
subsidence monitoring reports, and any level surveys completed for the purposes of subsidence monitoring or the addition, repair, or replacement of monuments in the subsidence monitoring network. The record of each level survey will include the following items:
 original copy of the field notes, certified and stamped by the licensed surveyor.
 listing of the adjusted elevations and their root mean square (RMS) error.
 listing of corrected horizontal distances and their RMS errors (if distance measurements were made).
 listing of adjusted horizontal coordinates and their RMS errors, if available; and
 any associated cross-section profile plots, subsidence contour maps, strain computation, and statistical analysis of changes in elevation, strain and horizontal coordinates.

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Subsidence Monitoring Plan 5-2 February 2025
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UIC Permit No. UTU-27-AP-BDCCF0C
ATTACHMENT D
Well and Cavern Closure and Abandonment Plan
UIC Permit No. UTU-27-AP-BDCCF0C
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UIC Permit No. UTU-27-AP-BDCCF0C
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UIC Permit No. UTU-27-AP-BDCCF0C
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UIC Permit No. UTU-27-AP-BDCCF0C
ATTACHMENT E
Financial Assurance
Memo – Revised Estimated Cost to Plug and Abandon Hydrogen Storage Caverns
at Delta, Utah
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UIC Permit No. UTU-27-AP-BDCCF0C
June 27, 2021
To: Division of Water Quality and ACES I, LLC
From: T. Eyermann
Subject: Revised Estimated Cost to Plug and Abandon Hydrogen Storage Caverns at Delta,
Utah
This memorandum presents a generalized process and estimate of the typical cost to plug and
abandon a hydrogen storage cavern at the Hydrogen Production and Storage Facility (Facility)
owned and operated by ACES I, LLC in Delta, Utah. Plugging and abandonment (P&A) of a
storage cavern may be necessary during Facility operations if the continued operation or
maintenance of the cavern presents a risk to public safety or the environment. The Division of
Water Quality (DWQ) may also require the P&A of a cavern if the Company is unable or unwilling
to maintain proper oversight and management of the cavern consistent with these requirements of
the Class III and V Underground Injection Control (UIC) Permits and other applicable regulations.
In the event a cavern P&A must be completed, the Company will develop and submit to the DWQ
for approval a detailed P&A Plan to address the specific circumstances of the individual storage
cavern.
Due to P&A costs being heavily influenced by the specific as-built and operational circumstances
of a storage cavern, this estimate is based on the following basic assumptions:
the hydrogen production plant will be functioning so that the storage cavern can be
emptied of hydrogen and filled with brine to create the static interior pressure conditions
required for abandonment;
the storage cavern will be approximately 5mmbbls in size;
the cavern well will have a 16” final cemented casing set at about 3,800 feet below ground
level (note: the depth and diameter of the casing greatly influences the amount of cement
and bentonite required);
a Mechanical Integrity Test (MIT) and sonar survey will need to be completed in advance
of the P&A (note: this step may not be necessary if an approved MIT and sonar survey of
the storage cavern has been completed within five years of the P&A);
the plugging technique will be to install three cement plugs in the cavern well - at the
surface, top and bottom (note: there are alternative plugging techniques that can be used
such as filling the entire wellbore with cement); and,
the bradenhead (flange on the last cemented casing) will be left in place at the completion
of the plugging work to allow continued post-P&A subsidence monitoring.
Based on these assumptions, the estimated duration to complete the entire P&A process of a storage
cavern is approximately fifteen weeks. This duration will allow enough time to complete all the
necessary steps from removing hydrogen from the cavern to completing the P&A process as
described in detail in the following bullet list and in the Class V UIC Permit Operations Plan. This
duration does not include Post P&A Monitoring that will consist of an annual survey, also descried
in the following bullet list.
P&A Process
Cavern Preparation:
o All stored hydrogen will be removed and the cavern will be filled with saturated brine
water until a 0 psi reading is achieved at the wellhead.
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UIC Permit No. UTU-27-AP-BDCCF0C
o This process should take approximately 10 weeks for a 5mmbbl cavern based on an
estimated two weeks to displace one million barrels of cavern space with brine.
o This involves bleeding the hydrogen back to the hydrogen production plant by
displacing the hydrogen with brine.
o The hydrogen pipeline between the Facility storage caverns and hydrogen production
plant will be used to convey gas back to the plant either for use or disposal.
o The brine transfer and pipeline system between the Facility brine evaporation ponds
and storage caverns will be used to pump brine into the cavern.
o The process of injecting brine to remove hydrogen will continue until brine is seen in
the hydrogen stream.
o A portable separator and flare system will be set up at the well to finish removing the
gas.
Cavern MIT:
o A MIT will be completed of the storage cavern/cavern well system in accordance with
the requirements of the Class V UIC Permit as outlined in the Operations Plan.
Cavern P&A Mobilization, Set-Up and De-Mobilization:
o A well rig will be transported and set up at the cavern well head to first complete a
sonar survey and then P&A of the cavern well.
o After P&A of the cavern well is complete, the well rig will be broken down and
transported off site.
Cavern Sonar Survey:
o A sonar survey of the storage cavern will be completed of the storage cavern in
accordance with the requirements of the Class V UIC Permit as outlined in the
Operations Plan.
Cavern Well Plugging:
o Remove all free hanging tubing from the well (if a sonar survey is necessary, this will
be completed prior to the sonar survey).
o Run wire line log to determine the exact depth to the bottom of the cemented
production casing.
o If casing conditions warrant, a scraper will be run from surface to bottom of the
cemented casing to remove scale or hydrogen from the casing.
o A drillable plug capable of supporting a cement plug will be installed below the
cemented casing with the bottom of the plug at least 10 feet below the end of the casing.
o The casing will be circulated clean utilizing brine or freshwater to remove any
contaminant from the stored hydrogen string that may adversely react with the cement
plugs (step 6).
o The following plugs will then be placed using Class G cement with no additives and
the slurry weight will be 14.5 pounds per gallon or more per DOGM regulations:
-Bottom plug: A 300-foot plug from the plug at the bottom of the production casing
upward.
-Surface casing plug: A 150-foot plug from 75 feet below the bottom of the surface
casing upward.
-Top plug: A 75-foot plug from 75 feet below surface grade upward to surface.
o The casing between each of the plugs shall be filled with a non-corrosive mud slurry
of at least 10 pounds per gallon weight.
Cavern P&A Reporting:
o All required reports will be filed in accordance with DWQ rules and Class V UIC
Permit conditions as applicable.
Post Cavern P&A Monitoring:
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UIC Permit No. UTU-27-AP-BDCCF0C
o Post P&A monitoring will consist of continued annual subsidence surveys for three
years.
o The survey should include monuments on the cavern that was plugged and abandoned
as well as other storage caverns in the vicinity.
The following table provides the estimated and duration and cost to complete each step in the P&A
process described above. Note that the estimate does not include the cost of electricity or manpower
to remove the bulk of the hydrogen to the surface facility or contingency.
P&A ACTIVITY ACTIVITY
DETAILS
DURATION EST. COST (US$)
Cavern Preparation Per steps above to
displace stored
hydrogen from cavern
with saturated brine
10 weeks $110,000
Cavern MIT Per Class V UIC
Permit Requirements
3 weeks $65,000
Cavern P&A Rig
Mobilization, Set-Up,
and De-Mobilization
Rig transportation,
set-up, breakdown,
supervision, labor
3 days $55,000
Cavern Sonar Survey Per Class V UIC
Permit Requirements
1 days $20,000
Cavern Well Pugging Per Steps Above (also
outlined in the Class
V UIC Permit
Operations Plan)
9 days $205,200
Cavern P&A
Reporting
Upon completion of
the plugging
operation, all reports
will be filed in
accordance with
DWQ rules and Class
V UIC Permit
conditions as
applicable.
N/A 4,000
Post Cavern P&A
Monitoring
Annual subsidence
monitoring of up to
four caverns @
$6,000 per annual
visit.
3 years $18,000
Total $477,200
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