DAQ-2025-001326

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DAQC-202-25
Site ID 12524 (B1)

MEMORANDUM

TO: FILE – PACIFICORP – Currant Creek

THROUGH: Harold A. Burge, Major Source Compliance Section Manager

FROM: Robert Haynes, Environmental Scientist III

DATE: February 20, 2025

SUBJECT: FULL COMPLIANCE EVALUATION, Major, Juab County,
FRS ID # UT0000004902300026

DATE OF INSPECTION: February 19, 2025

SOURCE LOCATION: 2096 West 300 North, Mona, UT 84645

Mailing Address:

PacifiCorp 1407 West North Temple, Suite 210
Salt Lake City, UT 84116

SOURCE CONTACTS: David Blackburn, Environmental and Safety Analyst: 435-623-3816
Tyson Kesler, Plant Manager: 435-623-3813

OPERATING STATUS: Operating

PROCESS DESCRIPTION: The power plant consists of two natural gas-fired turbine generators with
heat recovery steam generators with duct burning and a steam turbine.
The plant can produce 525 MW of electricity in combined cycle mode.
Emissions from the plant are controlled through good combustion
practices, a Selective Catalytic Reduction (SCR) system, and an
oxidation catalyst. Additional equipment includes a wet cooling tower,
emergency generator, an auxiliary boiler, fire pump, ammonia storage
and handling equipment, and water treatment and storage.

The source is allowed 10 months of simple cycle operation after initial
installation, with a requirement to convert to combined cycle operations
by the end of that 10-month period. Startup and shutdown periods will be
limited to 1,000 hours per year, and a maximum of 8 hours per day.

APPLICABLE
REGULATIONS: Approval Order (AO) DAQE-AN125240009-15, dated January 23, 2015,
40 CFR 63 subpart YYYY: Stationary Gas turbines HAPS – removed by
DAQC letter November 21, 2023.
40 CFR 60 Da/Dc included in AO
40 CFR 63 subpart ZZZZ: RICE engines
40 CFR 60 subpart IIII: RICE engines
40 CFR subpart 60 GG: Stationary Gas Turbines
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SOURCE INSPECTION
EVALUATION:

Section I: GENERAL PROVISIONS

I.1 All definitions, terms, abbreviations, and references used in this AO conform to those used in
the UAC R307 and 40 CFR. Unless noted otherwise, references cited in these AO conditions
refer to those rules. [R307-101]

Status: This is not an inspection item.

I.2 The limits set forth in this AO shall not be exceeded without prior approval. [R307-401]

Status: In compliance. See specific conditions below for compliance details.

I.3 Modifications to the equipment or processes approved by this AO that could affect the
emissions covered by this AO must be reviewed and approved. [R307-401-1]

Status: In compliance. No unapproved modifications were discovered.

I.4 All records referenced in this AO or in other applicable rules, which are required to be kept
by the owner/operator, shall be made available to the Director or Director's representative
upon request, and the records shall include the two-year period prior to the date of the request.
Unless otherwise specified in this AO or in other applicable state and federal rules, records
shall be kept for a minimum of two (2) years. [R307-401-8]

Status: In compliance. All requested records were provided.

I.5 At all times, including periods of startup, shutdown, and malfunction, owners and operators
shall, to the extent practicable, maintain and operate any equipment approved under this AO,
including associated air pollution control equipment, in a manner consistent with good air
pollution control practice for minimizing emissions. Determination of whether acceptable
operating and maintenance procedures are being used will be based on information available
to the Director which may include, but is not limited to, monitoring results, opacity
observations, review of operating and maintenance procedures, and inspection of the source.
All maintenance performed on equipment authorized by this AO shall be recorded.
[R307-401-4]

Status: In compliance. The source appeared to be maintained in a manner consistent with good
air pollution control practices.

I.6 The owner/operator shall comply with UAC R307-107. General Requirements: Breakdowns.
[R307-107]

Status: No breakdowns were reported or recorded since the last inspection.

I.7 The owner/operator shall comply with UAC R307-150 Series. Inventories, Testing and
Monitoring. [R307-150]

Status: In compliance. Emission inventories are submitted every 3 years. The last inventory was
submitted in 2024 for reporting year 2023. Testing and monitoring requirements are
specified in Section II: SPECIAL PROVISIONS below.

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Section II: SPECIAL PROVISIONS

II.A The approved installations shall consist of the following equipment:

II.A.1 Currant Creek Power Plant
Main Power Plant

II.A.2 #1: Turbine Generator Sets
Two (2) General Electric Frame 7 FA natural gas-fired turbine generator sets (140 MW
nominal capacity each in simple cycle mode), subject to NSPS GG, NESHAP YYYY

II.A.3 #2: Heat Recovery Steam Generators (HRSGS)
Two (2) HRSGs each equipped with 500 MMBtu/hr (HHV) duct burners with selective
catalytic reduction (SCR) system with ammonia injection and CO oxidation catalyst
system, subject to NSPS Da.

II.A.4 #2a HRSG Stacks
Two (2) Main Stacks (165' as measured from the base of the stack)
Each stack having bypass/breech for partial flow diversion, equipped with operator-
controlled shutoff dampers.

II.A.5 #3: Steam Turbine
One (1) steam turbine (250 MW nominal capacity in combined cycle mode).

II.A.6 #4: Auxiliary Boiler
One (1) natural gas-fired boiler rated at 66 MMBTU/hr, subject to NSPS Dc.

II.A.7 #5: Heater
One (1) natural gas-fired fuel heater.

II.A.8 #6: Emergency Generator
One (1) diesel-fired emergency generator rated at 800 kW.

II.A.9 #7: Pump
One (1) 250 hp diesel-fired pump.

II.A.10 #8: Misc Associated Equipment
Includes one (1) air-cooled condenser, one (1) mechanical draft cooling tower with drift
elimination, water treatment and storage facilities.

Status:

In compliance. No unapproved equipment was observed.

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II.B Requirements and Limitations

II.B.1 Conditions on Permitted Source

II.B.1.a The plant shall only be operated in combined cycle mode. The Bypass Stacks shall only be
used for periods of upset or breakdown conditions. The SCR and Oxidation Catalyst
systems shall be operated at all times that the combustion turbines are operated in combined
cycle mode. All emissions from the combustion turbines shall be passed through the SCR
and Oxidation Catalyst systems during combined cycle operation. [R307-401-8]

Status:

In compliance. The bypass stacks have been locked out from use. Upon startup, the
system must reach “mode 6” before combined cycle mode resumes operation. A mode
6 signal triggers ammonia injection and the SCR and oxidation catalyst systems begin
operating. All emissions from the turbines are passed through the SCR and oxidation
catalyst systems during combined cycle operation.

II.B.1.b Emissions to the atmosphere from each HRSG Stack shall not exceed the following rates
and concentrations:

PM/PM10: 0.066 lb/MMBtu HHV (13.3 lb/hour), 24-hour averaging period**
NOx: 2.25 ppmvd (17.0 lb/hr) at 15% O2*, 3-hour averaging period
CO: 3.0 ppmvd (11.6 lb/hr) at 15% O2*, 3-hour averaging period

* Excluding startups, shutdowns and short-term excursions as defined in Conditions II.B.1.c
and II.B.1.c.1

** Based on a 24-hour test run or any method acceptable to the Director, which will provide
24-hour data. [R307-401-8]

II.B.1.b.1 Stack testing to show compliance with the PM/PM10 emission limitations stated in the above condition shall be performed as specified below: Frequency: The HRSG Stacks shall be tested at least annually. The Director may require testing at any time. Notification: The Director shall be notified at least 30 days prior to conducting any required emission testing. A source test protocol shall be submitted to DAQ when the testing notification is submitted to the Director. The source test protocol shall be approved by the Director prior to performing the test(s). The source test protocol shall outline the proposed test methodologies, stack(s) to be tested, and procedures to be used. A pretest conference shall be held, if directed by the Director. Sample Location: The sampling location shall be designed to conform to the requirements of 40 CFR 60, Appendix A, Method 1, or other methods as approved by EPA and acceptable to the Director. An Occupational Safety and Health Administration (OSHA) or Mine Safety and Health Administration (MSHA) approved access shall be provided to the test location. Volumetric Flow Rate: 40 CFR 60, Appendix A, Method 2 or EPA Test Method No. 19 "SO2 Removal and PM, SO2, NOx Rates from Electric Utility Steam Generators" or other testing methods approved by EPA and accepted by the Director. PM/PM10:
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For stacks in which no liquid drops are present, the following methods shall be used: 40 CFR 51, Appendix M, Methods 201, 201a and 202 or other testing methods approved by EPA. All particulate captured shall be considered PM10. The back half condensables shall be used for compliance demonstration as well as for inventory purposes. For stacks in which liquid drops are present, methods to eliminate the liquid drops should be explored. If no reasonable method to eliminate the drops exists, then the following methods shall be used: 40 CFR 60, Appendix A, Method 5, 5a, 5d, or 5e as appropriate, or other testing methods approved by EPA. The back half condensables shall also be tested using the method specified by EPA. The portion of the front half of the catch considered PM10 shall be based on information in Appendix B of the fifth edition of the EPA document, AP-42, or other data acceptable to the Director. Calculations: To determine mass emission rates (lb/hr, etc.) the pollutant concentration as determined by the appropriate methods above shall be multiplied by the volumetric flow rate and any necessary conversion factors to give the results in the specified units of the emission limitation. Existing Source Operation: The production rate during all compliance testing shall be no less than 90% of the maximum production achieved in the previous three (3) years. [R307-165]
II.B.1.b.2 For the NOx and CO emission limitations listed above, compliance shall be demonstrated
through use of a CEMS as outlined in Condition II.B.1.g below. The Director may require
testing at any time.

Nitrogen Oxides (NOx):
40 CFR 60, Appendix A, Method 7, 7A, 7B, 7C, 7D, 7E, or other testing methods approved
by EPA and acceptable to the Director.

Carbon Monoxide (CO):
40 CFR 60, Appendix A, Method 10, or other testing methods approved by EPA and
acceptable to the Director.

In addition, the requirements for notification, sample location, volumetric flow rate,
calculations, and existing source operation shall be followed as outlined in Condition
II.B.1.b.1 above. [R307-165, R307-170]

Status: In compliance with stack testing requirements. Latest posted DAQ calculated test
results (DAQC-311-23) for PM10 were: CTG1A – 0.004 lb/MMBtu, 8.2 lbs/hr; CTG1B
– 0.006 lb/MMBtu, or 11.9 lbs/hr.

Most recent testing was conducted during the first full week of January 2025. CEM
requirements are evaluated by DAQ’s CEM specialist.

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II.B.1.c Compliance with the 3-hour NOx and CO emission limitations specified in Condition
II.B.1.b shall not be required during short-term excursions, limited to a cumulative total of
160 hours annually. Short-term excursions are defined as 15-minute periods designated by
the Owner/Operator that are the direct result of transient load conditions, not to exceed four
consecutive 15-minute periods, when the 15-minute average CO or NOx concentration
exceeds 3.0 and 2.25 ppmv, dry @ 15% O2, respectfully. Transient load conditions include
the following:

(1) Initiation/shutdown of combustion turbine inlet air cooling
(2) Rapid combustion turbine load changes
(3) Initiation/shutdown of HRSG duct burners
(4) Provision of Ancillary Services and Automatic Generation Control.

During periods of transient load conditions, emissions of NOx shall not exceed 25 ppmv, dry
@ 15% O2. [R307-401-8]

II.B.1.c.1 Startup is defined as the period beginning with turbine initial firing until the unit meets the
ppmvd emission limits in Condition II.B.1.b for steady state operation. Shutdown is defined
as the period beginning with the initiation of turbine shutdown sequence and ending with
the cessation of firing of the gas turbine engine. Startup and shutdown events shall not
exceed 1000 hours per turbine per calendar year. The cumulative startup and shutdown
period shall not exceed 8-hours in any one day, commencing at midnight. [R307-401-8]

Status:

In compliance. For 2024, the startup/shutdown hours for Unit 1 were 148.10 and Unit
2 were 118.80. Startup/shutdown hours did not exceed 8 hours in one day.

II.B.1.d Visible emissions from the following emission points shall not exceed the following values:
A. All natural gas combustion exhaust stacks - 10% opacity.
B. All other points - 20% opacity

Opacity observations of emissions from stationary sources shall be conducted according to
40 CFR 60, Appendix A, Method 9. [R307-401-8]

Status:

In compliance. No visible emissions were observed during this inspection. A visual
Method 22 survey is performed monthly. If any visible emissions are observed then a
Method 9 inspection would be performed.

II.B.1.e Emergency generators shall be used for electricity producing operation only during the
periods when electric power from the public utilities is interrupted, or for regular
maintenance of the generators. Records documenting generator usage shall be kept in a log
and they shall show the date the generator was used, the duration in hours of the generator
usage, and the reason for each generator usage. [R307-401-8]

Status:

In compliance. Emergency generator use logs were made available during this
inspection. The emergency generator has been exercised for 5-10 minutes weekly and
the fire pump has been exercised for roughly one-half hour weekly. For 2024, the
emergency engine ran 25.6 hours and the fire engine ran 7.80 hours.

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II.B.1.f The owner/operator shall use natural gas as fuel in the combustion turbines, duct burners,
fuel heaters and auxiliary boiler.

The owner/operator shall use #1, #2, or a combination of #1 and #2 diesel fuel in the
emergency generator and fire pump. [R307-401-8]

Status: In compliance. Only natural gas is used for fuel in the combustion turbines, duct
burners, fuel heaters, and auxiliary boiler. Only #1 or #2 diesel fuel is used in the
emergency generator and fire pump. Records from the refinery confirm compliance.

II.B.1.g The owner/operator shall install, calibrate, maintain, and operate a continuous emissions
monitoring system on the HRSG stacks. The owner/operator shall record the output of the
system, for measuring the NOx emissions and the CO emissions. The monitoring system
shall comply with all applicable sections of R307-170; 40 CFR 60.13; 40 CFR 60,
Appendix B; and 40 CFR 75.

All continuous emissions monitoring devices as required in federal regulations and state
rules shall be installed and operational prior to placing the affected source in operation.

Except for system breakdown, repairs, calibration checks, and zero and span adjustments
required under paragraph (d) 40 CFR 60.13, the owner/operator of an affected source shall
continuously operate all required continuous monitoring systems and shall meet minimum
frequency of operation requirements as outlined in 40 CFR 60.13 and Section R307-170.
[40 CFR 60 Subpart A, R307-170]

Status:

Not evaluated. CEM requirements are evaluated by DAQ’s CEM specialist.
II.B.1.h

The owner/operator shall install shutoff dampers in the bypass/breech point in each HRSG
stack such that the prevention of any diversion of exhaust gases is possible and under the
control of the owner/operator. The owner/operator shall not allow the diversion of exhaust
gases except during periods of steady-state operation. For purposes of this condition,
steady-state is defined as those periods when the unit is operating and not in startup or
shutdown as defined in Condition II.B.1.c.1. [R307-410-4, R307-410-5]

Status: In compliance. The bypass stacks have been locked out and are no longer used. The
hydraulically controlled dampers have been covered with a welded plate and the
dampers are removed.

40 CFR 60 Subpart GG:

60.330 – Currant creek is applicable to the definition.
60.332 – NOX standards. In Compliance. AO meets limits and CEMs reports in correct units.
60.333 – SO2 standards. In Compliance. The company complies with the use of NG which meets tariff
standards.
60.334 – Monitoring. In Compliance. The company complies with CEMS units and NG tariffs.
60.335 – Test methods. In Compliance. The company submits protocols and DAQ reviews testing.

40 CFR 63 ZZZZ and 40 CFR 60 IIII.
The two on-site generators from the equipment list are applicable. The company has one larger portable
unit for water transfers as needed. This unit is portable and not on site and is not subject to ZZZZ. The two
on-site units have non-resettable hour meters, annual inspections, and maintenance. The company does
weekly maintenance checks and runs. No unit ran in excess of 100 hours (see condition above).
Maintenance is tracked and scheduled through a program which meets subpart limits.
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EMISSION INVENTORY: 2023 emissions inventory database (received April 11, 2024):

Pollutant Tons/yr
PM10 ................................ 41.93
PM2.5 ............................... 41.93
SO2 .................................... 6.39
NOx ............................... 117.08
CO ................................... 39.80
VOC ................................ 22.53
NH3................................. 92.55

PREVIOUS ENFORCEMENT
ACTIONS: None within the last five years.

COMPLIANCE
ASSISTANCE: None

COMPLIANCE STATUS AND
RECOMMENDATIONS: This source should be considered in compliance with the
conditions of Approval Order DAQE-AN125240009-15, dated
January 23, 2015, evaluated at the time of this inspection.

HPV STATUS: Not Applicable

RECOMMENDATION FOR
NEXT INSPECTION: Check to see if the Title V permit has been issued.

ATTACHMENT: VEO form