DWQ-2024-000284

GROUND WATER QUALITY DISCHARGE PERMIT UGW270014
STATEMENT OF BASISAdvanced Clean Energy Storage I, LLCCooling and Blowdown Water Pond
Holladay, UT
January 2024
Introduction
The Division of Water Quality (DWQ) under the authority of the Utah Ground Water Quality Protection Rules 1(Ground Water Rules) issues ground water discharge permits to facilities which
have a potential to discharge contaminants to ground water2. As defined by the Ground Water Rules, such facilities includeminingoperations.3The Ground Water Rules are based on an anti-degradation
strategy for ground water protection as opposed to non-degradation; therefore, discharge of contaminants to ground water may be allowed provided that current and future beneficial uses
of the ground water are not impaired and the other requirements of Rule 317-6-6.4.A are met.4 Following this strategy, ground water is divided into classes based on its quality5; and
higher-quality ground water is given greater protection6 due to the greater potential for beneficial uses.
DWQ has developed permit conditions consistent with R317-6 and appropriate to the nature of the mined materials, facility operations, maintenance, best available technology7 (BAT) and
the hydrogeologic and climatic conditions of the site, to ensure that the operation would not contaminate ground water. Basis for Permit Issuance
Under Rule 317-6-6.4A, DWQ may issue a ground water discharge permit if:
The applicant demonstrates that the applicable class TDS limits, ground water quality standards protection levels and permit limits established under R317-6-6.4E will be met;
The monitoring plan, sampling and reporting requirements are adequate to determine compliance with applicable requirements;
The applicant is using best available technology to minimize the discharge of any pollutant; and
There is no impairment of present and future beneficial uses of ground water.
PurposeAdvanced Clean Energy Storage I, LLC (ACES) is constructing a hydrogenproduction and storage facility in Millard County, Utah approximately 10 miles north of Delta. The Project
entails solution mining storage caverns in a subsurface salt deposit for the purpose of storing hydrogen.The hydrogen to be stored will be produced on-site at a tobeconstructed hydrogen
production facility. The cooling and blowdown waste water will be stored for evaporation in an above-groundlined pond. The Project lies within an approximately 321-acre site located
on Utah School and Institutional Trust Lands Administration (SITLA) lands.
Ground Water Discharge Permit UGW270014is beingissued to authorize the construction of one cooling and blowdown water evaporation pondand the installation of additional unconfined water
table aquifer compliance monitoring wells. Ground Water Discharge Permit UGW270014is being issued with the associated construction permit for the construction of the pond.
New FacilitiesThe following new facilities will be regulated under this Permit including the associated Best Available Technology (BAT), Protection Levels (Table 2) and requirements
for monitoringthe cooling and blowdown water pond. The cooling and blowdown water pondfootprint is approximately 34 acres with a storage area measuredthree feet below the crest of the
berm of approximately 25acres. The cooling and blowdown water pond isconstructed using a combination of excavation into the ground surface and the construction of elevated berms.
The cooling and blowdown water pond is constructed with a single 60-mil high-density polyethylene liner. The liner will be sitting on top of the leak collection and infiltration prevention
(LCIP) system. The system consists of four quadrants, each with lined drainage collection swales, trenches, and a sump. The LCIP system will capture and direct to the sumps, leakage
from the primary single liner. The sumps will be monitored and pumped back into the pond to provide a leak detection measurement and to limit infiltration from the primary liner.
The pond will have a set of compliance monitoring wells installed up and down-gradient of the berm walls for the protection of groundwater. The berms will have piezometers installed
which will be monitored for liquid levels in the berms as an additional leak detection tool.BAT Performance MonitoringBest available technology monitoring will include minimum vertical
freeboard and maximum allowable leakage rate monitoring. These performance standards are based on the precedence of previous groundwater discharge permits and Action Leakage Rates For
Leak Detection Systems (USEPA, Office of Solid Waste, January 1992). Minimum Vertical Freeboard. A minimum of 36 inches of vertical freeboard shall be maintained to ensure total containment
of solution mining liquids. Maximum Allowable Leakage Rate. The leak detection system is the primary compliance monitoring point because it is the early warning system that demonstrates
protection of ground water quality. The estimated maximum liner leakage rate was established by standard engineering practice using the method described in Equations for Calculating
the Rate of Liquid Migration through Composite Liners due to Geomembrane Defects (Giroud, 1997). Based on a pond water surface area of approximately 25acres, the maximum allowable leakage
rate through the primary HDPE liner is 8 gallons per minute.Maximum Allowable Head. The maximum allowable head imposed on the leak detection sumpswill be determined following system
construction. Any fluids collected in the leak detection sump will be pumped back to the brine evaporation ponds. As long as the leak detection system complies with the BAT performance
standards of the permit, the facility is compliant. In the event that the leak detection system has flows or heads that exceed the BAT performance standards of the permit, a BAT failure
exists and the permittee will be required to regain BAT by a number of solutions including identifying and repairing the BAT failure.
Potential Impacts to Ground Water
Potential impacts to ground water have been minimized by employing best available technology for the cooling and blowdown water pond. The Division of Water Quality will provide periodic
onsite inspections during construction and operation of the facilities described above. The Cooling and Blowdown Water Pond Operating Manual/Standard Operating Planwill ensure that
the facility is operated in accordance with design specifications and will also ensure that any indications of facility problems will be detected early and resolved. In addition to
BAT performance monitoring, ground water quality monitoring of the water table aquifer will be conducted in monitoring wells to determine if ground water quality has been impacted by
leakage from the brine evaporation pond.
Geologic Description
Regional. The brine evaporation pondis situated over a subsurface salt deposit in the Sevier – Black Rock Desert in the Basin and Range physiographic province of Utah. The mountains
that surround the basin of the Sevier Desert are composed of a variety of consolidated sedimentary, metamorphic and igneous rock. The basin is underlain by deposits that consist primarily
of semi-consolidated and unconsolidated sediments of Tertiary and Quaternary age. The basin-fill includes sand, silt, clay and gravel deposited as alluvial fans, stream alluvium, mudflows,
lacustrine (lake) sediments and deltas. The basin fill also contains scattered basalt flows and tuffs of late Tertiary and Quaternary age. Tertiary and Quaternary basin-fill deposits
are over 7,000 feet thick. Oligocene and Miocene basin-fill sediments contained evaporate deposits. Through time, evaporites in the area flowed to form a salt dome.
The soil profile at the site consists of three units. The upper unit is comprised of fine-grained glacial lacustrine deposits consisting of deep-water calcareous silts and may contain
younger alluvium up to 10 feet thick. The upper unit is underlain by pre-Lake Bonneville alluvium consisting of sand and sandy gravel beds. The lower unit consists of alluvium, silt
and sandy silt deposited in large low-gradient alluvial fans, river terraces, and abandoned river channels on the river delta. This unit ranges up to 30 feet in thickness.
Hydrogeology
The principal regional groundwater system is the unconsolidated basin-fill deposits that formed from erosion of the surrounding mountains and were laid down by streams, lakes, and mudflows.
These regional deposits consist of interbedded and lenticular deposits of clay, silt, sand, gravel and boulders. The regional depositional processes created alternating and interfingering
layers and lenses with regional horizontal and vertical heterogeneity. Differences in sorting and grain size influence local permeability and storage capacity, which can vary greatly
depending on the nature of local depositional processes. Sediments are generally coarser near the mountain front and grade finer towards the valley centers. Stream channel deposits are

coarser and better sorted than alluvial fan and mudflow deposits that generally occur at the base of steep drainages. Vast lakes that occupied the valleys many thousands of years ago
deposited interbedded clay and finegrained sands. Rivers flowing into these lakes formed coarse-grained delta deposits near the ancient lake shore, such as near the mouth of Leamington
Canyon.
Recharge to the principal groundwater aquifer system (basin-fill deposits) in the Sevier Desert occurs by stream infiltration along mountain fronts, subsurface inflow from consolidated
rocks of mountain areas, subsurface inflow from adjoining basins, seepage from rivers, canals, reservoirs and unconsumed irrigation. Groundwater generally flows from recharge areas near
the mountains on the northeast and east of the Sevier Desert toward discharge areas in the central and western parts of the area.
Aquifers in the area have been clearly defined using data collected during the installation of multiple wells constructed in the region around the Magnum and ACES site, including Magnum’s
MH-1 Test Well (constructed in 2009). The unconfined water table aquifer is located above the shallow artesian aquifer and is generally confined to the upper 50 to 150 feet, the shallow
artesian aquifer to depths of about 150 to 700 feet, and the deep artesian aquifer between about 700 to 1,400 feet (the bottom of historically drilled wells). A previously undefined
deeper confined aquifer (defined as the basement aquifer) is located at depths greater than 1,400 feet.
Ground Water Quality
Ground Water Classification.In accordance with UAC R317-6-3.5 and ground water quality data provided in the permit application which includes ground water monitored in nearby groundwater
compliance wells, is classified as Class II Drinking Water Quality Ground Water. As required in Part II.H.3 of the permit, an accelerated background monitoring program will be completed
by the permittee to collect data for calculating well-specific background ground water quality statistics. After securing Director approval of the Accelerated Background Monitoring
Report, background concentrations may be adjusted in accordance with the reopener provision in Part V.N of the permit.
Class II Protection Levels.In accordance with UAC R317-6-4.5, Class II ground water will be protected for use as drinking water or other similar beneficial use with conventional treatment
prior to use. Class II protection levels are established in accordance with the following criteria in UAC R317-6-4.2B:a.Total dissolved solids (TDS) may not exceed the greater of 1.25
times the background concentration or the background plus two standard deviations.b.When a contaminant is present in a detectable amount as a background concentration, the concentration
of the pollutant may not exceed the greater of 1.25 times the background concentration, 0.25 times the ground water quality standard, or background plus two standard deviations; however,
in no case will the concentration of a pollutant be allowed to exceed the ground water quality standard.c.When a contaminant is not present in a detectable amount as a background concentration,
the concentration of the pollutant may not exceed the greater of 0.25 times the ground water quality standard, or the limit of detection. Compliance Schedule Cooling and Blowdown Water
Pond Operating Manual/Standard Operating Plan. Pond monitoring, operation, maintenance, and repair procedures shall be described in the manual for Director review and approval before
authorization to operate is granted.The Operating Manual will also describe the timeline for pond filling over several years and will develop pond level-specific leak rates for the filling
schedule until the pond is operating at full design capacity. This will ensure that a leak that is below the manufacture-rated 8 gpm but above what should be expected at a lower fill
level will be detected.Accelerated Background Monitoring Report. Newly installed ground water monitoring wells shall be sampled on a quarterly frequency for 8 consecutive quarters.
Statistical calculations shall be presented in the report for the purposes of establishing ground water class protection levels in accordnce with UAC R317-6-4. Final Closure Plan.
In the event that the permittee decides to discontinue its operations at the facility the permittee shall notify the Director of such a decision and submit a Final Closure Plan within
180 daysprior to the closure of the facility.
Permit Application DocumentsThe documents that comprise the Groundwater Discharge Permit Application (for ACES Cooling and Blowdown Water Pond) submitted under cover letter dated June19,
2023 by ACES I, LLC and subsequent revisions are considered part of the administrative file for this permit.