DWQ-2024-003409

UIC Permit No. UTU-27-AP-718D759
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ATTACHMENT A

General Location Map of the Magnum Storage Project, Millard County.
UIC Permit No. UTU-27-AP-718D759
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UIC Permit No. UTU-27-AP-718D759
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ATTACHMENT B

Map of the Magnum Storage Project Area of Review (AOR) including the Class V
Hydrogen Injection and Withdrawal Wells and the Permit Area

UIC Permit No. UTU-27-AP-718D759
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UIC Permit No. UTU-27-AP-718D759
DRAFT

ATTACHMENT C

Hydrogen Storage Cavern Field Operating, Monitoring and Reporting Plan (Draft)

Hydrogen
Storage Cavern
Field Operating,
Monitoring and
Reporting Plan
Class V Underground
Injection Control Permit
(UTU-27AP-BDCCF0C)
Hydrogen Storage Cavern
Field Operating, Monitoring, and
Reporting Plan
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
December 2021
(Revised April 2024)
Prepared by
Advanced Clean Energy Storage I, LLC
3165 E. Millrock Dr., Suite 330 Holladay,
Utah 84121
Tel [phone] Fax [phone]
Hydrogen Cavern Field Operating Plan i April 2024
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

Hydrogen Cavern Field Operating Plan ii April 2024
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

Hydrogen Cavern Field Operating Plan 1-1 April 2024
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.

Hydrogen Cavern Field Operating Plan 1-2 April 2024

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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 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.

Hydrogen Cavern Field Operating Plan 1-4 April 2024

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Hydrogen Cavern Field Operating Plan 1-5 April 2024
Figure 2. Facilities Map

Hydrogen Cavern Field Operating Plan 1-6 April 2024
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)

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

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

Hydrogen Cavern Field Operating Plan 1-7 April 2024
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

Hydrogen Cavern Field Operating Plan 1-8 April 2024
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.

Hydrogen Cavern Field Operating Plan 1-9 April 2024

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Hydrogen Cavern Field Operating Plan 2-1 April 2024
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

Hydrogen Cavern Field Operating Plan 2-2 April 2024
thresholds does not occur. The Class III UIC Permit established a minimum allowable operating
pressure gradient (MinAOPG) of to the last cemented
casing shoe and a maximum allowable operating pressure gradient (MaxAOPG) of
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, MaxAOPG
and test pressure will be required at all times during operations and maintenance:

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 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
(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: below:
o Salt thickness is a minimum of above the cavern;
o The casing seat is a minimum of cavern roof;
o The maximum cavern diameter is less than or equal to
o The cavern height is less than or equal to ;

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.

Hydrogen Cavern Field Operating Plan 2-3 April 2024
o The cavern storage volume remains less than or equal to

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 above 2 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
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
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
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

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.

Hydrogen Cavern Field Operating Plan 2-4 April 2024
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 3-1 April 2024
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 Stable reference monuments are located more than 7000 feet beyond the expected
subsidence radius to provide stable points 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. These points are located above the center of
the cavern well field, and at approximately 480, 600, 750, 1500, 2500, 5000, 6000,
6350, 7000 feet out from the center of the cavern well field to provide good coverage
for 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.

Hydrogen Cavern Field Operating Plan 3-2 April 2024
 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.

Hydrogen Cavern Field Operating Plan 3-3 April 2024
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.

Hydrogen Cavern Field Operating Plan 3-4 April 2024
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

Hydrogen Cavern Field Operating Plan 3-5 April 2024
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

Hydrogen Cavern Field Operating Plan 3-6 April 2024
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

Hydrogen Cavern Field Operating Plan 3-7 April 2024
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 MATP 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,

Hydrogen Cavern Field Operating Plan 3-8 April 2024
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.

Hydrogen Cavern Field Operating Plan 3-9 April 2024

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Hydrogen Cavern Field Operating Plan 4-1 April 2024
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.

Hydrogen Cavern Field Operating Plan 4-2 April 2024
 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 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,
Hydrogen Cavern Field Operating Plan 4-3 April 2024
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.

Hydrogen Cavern Field Operating Plan 4-4 April 2024

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Hydrogen Cavern Field Operating Plan 5-1 April 2024
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.

Hydrogen Cavern Field Operating Plan 5-2 April 2024
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Appendix A
Storage Cavern Wellhead
Summary Tables

Typical Wellhead Pressures for Solution Mining and Hydrogen Storage
Operation Casing
(inches)
Fluid Pressure
Loss
(psi)
Casing
(inches)
Fluid Pressure
Loss
(psi)
Static
Head
(psi)
Water/Product
Line Pressure
Loss
(psi)
Brine/Water
Line
Pressure
Loss
(psi)
Surface
Pressure
(psi)
Direct
Mining

Appendix B
Inventory Verification
Methodology
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1
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
4/8/2021
2
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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3
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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4
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 sonar 3 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.
4/8/2021
5
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
4/8/2021
6
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.

Appendix C
Subsidence Monitoring Plan

Subsidence
Monitoring Plan
Subsidence Monitoring Plan
Advanced Clean Energy Storage I,
LLC
Hydrogen Production and
Storage Facility
Delta, Utah
April 2021
(Revised April 2025)
Prepared by
Advanced Clean Energy Storage I, LLC
3165 E. Millrock Dr., Suite 330
Holladay, Utah 84121
Tel [phone] Fax [phone]

Subsidence Monitoring Plan i April 2024
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 April 2024
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

Subsidence Monitoring Plan 1-2 April 2024

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

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
bgs and the base of caverns will range in depth between
bgs. The timing of construction of each cavern within the Storage Cavern Field will be dependent
upon market demand.

Subsidence Monitoring Plan 1-3 April 2024
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 7,400 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.

Subsidence Monitoring Plan 2-1 April 2024
Section 2
Subsidence Monitoring System
2.1 Subsidence Monitoring Network
The Subsidence Monitoring Network for the Facility will be comprised of 20 new and existing
monitoring and stable reference monuments: six new monitoring monuments installed by the
Company, 11 subsidence monuments from an existing radial network and three existing stable
reference monuments. The radial network and stable reference monuments 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
 three existing stable reference point monuments (SR-1 at 7,100’, SR-2 at 6,350’, and the
main control 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 (-1 and H-2); and
 three fresh water wellhead subsidence monuments (GRN-MH-1, GRN-MH-2, and
GRN-MH-3).

Subsidence Monitoring Plan 2-2 April 2024
Of the 20 monitoring monuments, 12 are local deep surface subsidence monuments (all but H-1,
H-2, GRN-MH-1, GRN-MH-2, GRN-MH-3, SR-1, SR-2 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, five subsidence monuments will function as bedrock monuments
via the installed well casings for water wells GRN-MH-1, GRN-MH-2, and GRN-MH-3, and
storage cavern wells H-1 and H-2, 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 are three stable reference points that are also part of the subsidence monument network: two
existing stable reference point monuments to provide coverage up to 7,400 feet beyond the center
of the Storage Cavern Field, and an existing main control point monument located approximately
6,000 feet from the center of the Storage Cavern Field. These points will serve through time as
stable reference points for the entire subsidence monitoring network as the monuments are 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).

Subsidence Monitoring Plan 2-3 April 2024

Subsidence Monitoring Plan 3-1 April 2024
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 using a transit and graduated rod.
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 4-1 April 2024
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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Seismic Monitoring Plan 5-1 April 2024
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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UIC Permit No. UTU-27-AP-718D759
DRAFT

ATTACHMENT D

Well and Cavern Closure and Abandonment Plan

UIC Permit No. UTU-27-AP-718D759
DRAFT

UIC Permit No. UTU-27-AP-718D759
DRAFT

UIC Permit No. UTU-27-AP-718D759
DRAFT

UIC Permit No. UTU-27-AP-718D759
DRAFT

ATTACHMENT E

Financial Assurance
Memo – Revised Estimated Cost to Plug and Abandon Hydrogen Storage Caverns
at Delta, Utah

UIC Permit No. UTU-27-AP-718D759
DRAFT

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
UIC Permit No. UTU-27-AP-718D759
DRAFT

UIC Permit No. UTU-27-AP-718D759
DRAFT

Total $477,200