DAQ-2024-004554

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DAQC-CI105710001-23a
Site ID 10571 (B1)

MEMORANDUM

TO: FILE – RIO TINTO KENNECOTT UTAH COPPER LLC – Bingham Canyon
Mine

THROUGH: Chad Gilgen, Minor Source Compliance Section Manager

FROM: Connor Kijowski, Environmental Scientist

DATE: October 16, 2023

SUBJECT: FULL COMPLIANCE EVALUATION, Minor, Salt Lake County

INSPECTION DATE: August 9, 2023

SOURCE LOCATION: 8362 West 10200 South
Bingham Canyon, 84006
SOURCE CONTACTS: Sean Daly, Senior Environmental Advisor
801-204-2563, [e-mail]

OPERATING STATUS: Operating normally at the time of inspection.

PROCESS DESCRIPTION: The open pit mine produces ore to be crushed, concentrated, and
refined into several metals including copper, gold, silver,
molybdenum, and others. The mining location within the pit is
decided by the use of a computer system that engineers use to
determine ore quality. Drill holes are plotted on a pit map and
surveyed at the designated area to be mined. A drill truck is then
dispatched to the blast area and drills holes by wet drilling.
These holes are filled with blasting agent and blasted or
imploded when ready.

Blasted areas are excavated by loading ore into haul trucks with
electric shovels and hauling it to the Main In-Pit Crusher. This
ore is ground into finer sized material and conveyed to
Kennecott's concentrator area. Emissions from conveyors are
controlled by baghouses located at enclosed transfer points.

Overburden and waste is hauled to the dumping slopes at the
edge of the pit. Low-grade ore is hauled to storage areas and may
be used as backup in the event of mining disruptions or other
bottlenecking issues which may limit activity at other areas of
Kennecott's operations.

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APPLICABLE REGULATIONS: Approval Order (AO) DAQE-AN105710047-21, dated May 10,
2021
NSPS (Part 60) - LL : Standards of performance for Metallic
Mineral Processing Plants,
NSPS (Part 60) - IIII : Standards of Performance for Stationary
Compression Ignition Internal Combustion Engines,
NSPS (Part 60) - JJJJ : Standards of Performance for Stationary
Spark Ignition Internal Combustion Engines,
NSPS (Part 60) - OOO : Standards of Performance for
Nonmetallic Mineral Processing Plants,
MACT (Part 63) - ZZZZ : National Emissions Standards for
Hazardous Air Pollutants for Stationary Reciprocating Internal
Combustion Engines
UTAH STATE IMPLEMENTATION PLAN (SIP)

SOURCE EVALUATION:

Name of Permittee: Permitted Location:

Rio Tinto Kennecott Utah Copper LLC -
Mine & Copperton Concentrator

4700 Daybreak Parkway 8362 West 10200 South
South Jordan, UT 84095 Bingham Canyon, 84006

SIC Code: 1021: (Copper Ores)

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]

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

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]

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]

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]

I.6 The owner/operator shall comply with R307-150 Series. Inventories, Testing and Monitoring.
[R307-150]

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I.7 The owner/operator shall comply with UAC R307-107. General Requirements: Breakdowns.
[R307-107]

Status: In Compliance. The source appears to be in compliance with each condition of
Section I. A breakdown was reported March 2023, for the conveyor transfer point between
the mine and concentrator. Rio Tinto submitted a temporary relocation permit (C-300-23)
to install and operate a generator during maintenance. Proper notification was received
according to UAC R307-107. The 2022 Emission Inventory was submitted by the required
date and the values are included below.

Section II: SPECIAL PROVISIONS

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

II.A.1 KUC Bingham Mine
KUC operates the BCM. KUC removes ore from the BCM by drilling, blasting, crushing and
hauling.

II.A.2 Main In-pit Crusher
Main in-pit crusher
Main in-pit crusher baghouse

II.A.3 Portable Roadbase Crushers
Two portable crushing and screening plants used to crush material for road base
Maximum crusher unit capacity 700 tons per hour, each

II.A.4 Conveyors
Conveyors and two transfer points with baghouses (Baghouses C6/C7 and Baghouses C7/C8)

II.A.5 Lime Silos
Lime silos with fabric type bin vent control units

II.A.6 Sample Preparation Equipment
Sample preparation equipment with baghouse

II.A.7 SX/EW plant
SX/EW plant with electrowinning acid mist eliminator

II.A.8 Degreasers
Various degreasing parts washers

II.A.9 Gasoline Fueling Stations

II.A.10 LPG-Fired Emergency Generators
Nine Liquefied Petroleum gas-fired emergency generators

Site Maximum Rating
Lark Gate
#1 107 Brake Horsepower (BHP)
#2 49 BHP
Production Control Building 6690 150 BHP
Communications 6190 75 BHP
Mandy's Landing 75 BHP
East Side Dump 49 BHP
Zelnora 49 BHP
SAM Site 49 BHP
Substation 2 49 BHP

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II.A.11 Diesel-Fired Emergency Generators
Five diesel-fired emergency generators

1) Support Generator 1
Maximum rating 2,250 kW

2) Support Generator 2
Maximum rating 700 kW

3) Support Generator 3
Maximum rating 700 kW

4) Support Generator 4
Maximum rating 500 kW

5) Support Generator 5
Maximum rating 2,000 kW

II.A.12 Concrete Batch Plant

1) One 25 cubic yard per hour batch plant controlled by a baghouse

2) One cement storage silo controlled by a baghouse

3) Conveyors and cement trucks

4) Storage silos with fabric filters

II.A.13 Crushers and Screens
Portable crushing and screening plants with associated conveyors used to crush ore and waste rock.
Conveyors partially enclosed transfer points or water sprays

II.A.14 Under Ground Mining Support Equipment
1) One (1) 150 cubic yard per hour batch plant controlled by baghouse
a) One (1) cement storage silo controlled by baghouse
b) Conveyors and cement trucks
c) Storage silos with fabric filters

2) One (1) natural gas-fired boiler rated at maximum of 2.0 MMBTU/hr

3) One (1) natural gas-fired boiler rated at maximum of 4.0 MMBTU/hr

4) Three (3) diesel-fired heaters, each rated maximum of 4.2 MMBTU/hr

5) One (1) diesel-fired generator, rated maximum of 71 kW

Status: In Compliance. No unapproved equipment was observed during the inspection.
Additional equipment information is listed below:

II.A.6: The lime silos are installed at the concentrator but are listed on both mine and
concentrator AOs
II.A.7: SX/EW plant was shut down in 2015
II.A.10: Zelnora generator was removed from the site,
Building 6690 listed generator is at building 6190
II.A.11: Generators 3, 4, and 5 have been not installed and generator 2 has been
installed but is not operating,
II.A.12: 25 cubic yard batch plant has not yet been installed
II.A.14: The concrete batch plant has not been installed yet, the source sent a
notification on September 3, 2022, stating that they are starting construction. The
source has not finished construction as of this inspection. Additionally, the diesel-
fired generator is currently not installed for underground mining.
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II.B Requirements and Limitations

II.B.1 Limitations and Test Procedures.

II.B.1.a Emissions at all times from the indicated emission points after primary control shall not exceed
the following rates and concentrations:

A. Main In-Pit Crusher Baghouse Vent

Pollutant lb/hr grains per dry standard cubic foot (dscf)
(68oF, 29.92 in Hg)

PM10 1.77 0.016
PM2.5 0.78 0.007

B. Controlled Drop Point Baghouse Vent @ Tunnel Exit Near Copperton (C6/C7)

Pollutant lb/hr grains per dry standard cubic foot (dscf)
(68oF, 29.92 in Hg)

PM10 0.31 0.007

C. Controlled Drop Point Baghouse Vent @ Copperton (C7/C8)

Pollutant lb/hr grains per dry standard cubic foot (dscf)
(68oF, 29.92 in Hg)

PM10 0.19 0.007. [R307-401-8]

Status: In Compliance. Stack testing has been performed and results have been submitted
to DAQ for review. DAQ-calculated test results are as follows:

Unit Test Date Results lb/hr Results gr/dscf
In-pit Crusher PM2.5 10/29/2021 0.156 0.0011
In-pit Crusher PM10 10/29/2021 0.563 0.0038
C6/C7 (Removed 2020) 11/14/2019 0.028 0.0007
C7/C8 (renamed C6/C8) 3/25/2022 0156 0.00397

II.B.1.b Stack testing to show compliance with the emission limitations stated in the above condition
shall be performed as specified below:

A. Testing Test
Emissions Point Pollutant Status Frequency

Main In-Pit Crusher Baghouse
Vent PM10 * #
PM2.5 * #

Controlled Drop Point Baghouse
Vent @ Tunnel Exit Near
Copperton (C6/C7) PM10 * #

Controlled Drop Point Baghouse
Vent @ Copperton (C7/C8) PM10 * #

B. Testing Status

* The initial testing has already been performed.

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# Test every three years. If a unit is not in operation when a test is due, the owner/operator
may request an extension for the test.

C. Notification

The Director shall be notified at least 30 days prior to conducting any
required emission testing. A source test protocol shall be submitted
with 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, and stack to be tested. A pretest conference shall be held, if
directed by the Director.

D. Sample Location

The emission point shall be designed to conform to the requirements of 40 CFR
60, Appendix A, Method 1, or other EPA approved methods 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.

E. Volumetric Flow Rate

40 CFR 60, Appendix A, Method 2 or other EPA approved testing methods acceptable
to the Director.

F. PM10/PM2.5

For stacks in which no liquid drops are present, the following methods shall be used:
40 CFR 51, Appendix M, Methods 201 or 201a or other EPA-approved testing method
acceptable to the Director. The back half condensable particulate emissions shall also
be tested (where applicable) using 40 CFR 51, Appendix M Method 202, or other
EPA-approved testing method acceptable to the Director. All particulate captured using
Method 202 shall be considered PM2.5 and/or PM10.

For stacks in which liquid drops are present, methods to eliminate the liquid drops shall 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, 5i or other as appropriate. If using
Method 5 or any variation of Method 5, a scanning electron microscopy analysis or other
equivalent method shall be used to determine the fraction of PM10 and/or PM2.5, as approved
by the Director. The back half condensable particulate emissions shall also be tested using
40 CFR 51, Appendix M Method 202 or other EPA-approved testing method acceptable to the
Director. All particulate captured using Method 202 shall be considered PM2.5 and/or PM10.

For filterable emission limits, condensable emissions shall not be used for compliance
demonstrations. For filterable + condensable emission limits, both filterable and condensable
emissions shall be used for compliance demonstrations. [R307-401-8]

Status: In Compliance. Stack testing for C6/C7 was done in November, 2019; but the
transfer point has since been removed. Main pit crusher was tested October 29, 2021; due
again in 2024. Transfer point C7/C8 has been renamed C6/C8 at the source. The C6/C8
transfer point baghouse was tested on October 29, 2022, but failed and a compliance
advisory and early settlement agreement was sent to the source (see DAQC-015-22 and
DAQC-134-22). It was retested on March 25, 2022, and was determined to be in compliance
(DAQC-882-22), and will be due again in 2025.

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II.B.1.c G. 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 determined by the
Director, to give the results in the specified units of the emission
limitation.

H. Source Operation

For a new source/emission point, the production rate during all compliance testing
shall be no less than 90% of the production capacity of the equipment. If the
maximum production capacity has not been achieved at the time of the test, the
following procedure shall be followed:

1) Testing shall be at no less than 90% of the production rate achieved to date.

2) If the test is passed, the new maximum allowable production rate shall
be 110% of the tested achieved rate. This new allowable maximum
production rate shall remain in effect until successfully tested at a higher rate.
This process may be repeated until the maximum AO production rate is
achieved.

For an existing source/emission point, the production rate during all compliance
testing shall be no less than 90% of the maximum production achieved in the previous
three years. [R307-401-8]

II.B.1.d Visible emissions from the following emission points shall not exceed the following values:

A. Main In-Pit crusher baghouse vent 7% opacity

B. Controlled drop point baghouse vent
@ tunnel exit near Copperton (C6/C7) 7% opacity

C. Controlled drop point baghouse vent
@ Copperton (C7/C8) 7% opacity

D. Concrete batch plant baghouse 10% opacity

E. All other conveyor transfer points 10% opacity

F. Lime silos 10% opacity

G. Sample preparation equipment with
baghouse 10% opacity

H. Drilling 10% opacity

I. LP gas-fired emergency generators 10% opacity

J. Nonmetallic Mineral Processing Screens
and Conveyors 7% opacity

K. Nonmetallic Mineral Processing Crushers 12% opacity

L. Metallic Mineral Processing Equipment 10% opacity

M. Electrowinning Plant with electrowinning
acid mist eliminator 15% opacity

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N. All other points except as defined in other
conditions of this AO 10% opacity

Opacity observations of emissions from stationary sources shall be conducted according to 40
CFR 60, Appendix A, Method 9. [R307-201]

Status: In Compliance. The C6/C7 controlled drop point has been removed, and the C7/C8
controlled drop point was renamed to C6/C8 at the source. A VEO was performed on the
C6/C8 controlled drop point baghouse; no opacity was observed. No excess emissions were
noted from any other emission point during the inspection. Refer to the VEO Form for
more details.

II.B.1.e For sources that are subject to NSPS, opacity shall be determined in accordance with 40 CFR
60.11(b) and 40 CFR 60, Appendix A, Method 9. It is the responsibility of the owner/operator of
the source to supply these observations to the Director.

A current certified observer must be used for these observations. Emission points that are subject
to the initial observations are:

A. All crushers

B. All screens

C. All conveyor transfer points. [40 CFR 60 Subpart A]

Status: In Compliance. Previous inspections indicate initial observations on the equipment
occurred on July 1, 1993. The road base crushing plant was modified in 2018, and initial
opacity observations for it occurred on July 16, 2018 (DAQC-2018-013021).

II.B.1.f The following limits shall not be exceeded:

A. Total material moved (ore and waste) shall not exceed 260,000,000 tons
per rolling 12-month period*.

B. Annual emissions of SO2 shall not exceed 7 tons per rolling 12-month period.

C. Maximum total mileage per calendar day for diesel-powered ore and waste haul
trucks shall not exceed 30,000 miles.

D. Minimum design payload per ore and waste haul truck shall not be less than 240 tons.
Minimum design payload for trucks hauling material to develop new mining
technologies, and material from maintenance activities shall not be less than 40 tons.
Trucks used for underground development and operation may be smaller depending
on application.

E. Maximum number of wheels per ore or waste haul truck shall not exceed six wheels.

F. Height of mine waste dump lift shall not exceed 1000 feet.

G. The surface area of the Solvent Extraction/Electrowinning Plant mixer/settlers
shall not exceed 1,100 ft2.

*Total ore and waste limitation shall be applied to dry tons of new material mined at the
production shovels face.

The owner/operator shall determine compliance with the 12-month period limits on a rolling 12-
month total. The owner/operator shall calculate a new 12-month total by the twentieth day of
each month using data from the previous 12 months.

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The owner/operator shall keep records of daily total mileage for all periods when the mine is in
operation. The owner/operator shall track haul truck miles with a Global Positioning System or
equivalent. The system shall use real time tracking to determine daily mileage.

SO2 emissions from fuel burning shall be determined using the following formula:

SO2 tpy = (gal fuel/year)*(7.05 lb/gal)*(%S by wt.)/2000 lb/ton*(2 lb SO2/lb S). [R307-401-8]

Status: In Compliance.

A: This information is tracked on the Mine Management system and showed 11,829,450
tons for the 12-month period ending in June 2023.

B: This is tracked through fuel use as card and showed 2.16 tons for the 12-month period
ending in June 2023.

C: Daily mileage is tracked on each truck through GPS and is recorded automatically.
Tracker shows total mileage as well as highest day mileage. Highest day mileage showed no
day over the allowed limit. Highest June 2023, daily number was 14,019, May daily number
was 13,470, and April daily number was 12,819 miles based on spread sheet formula for
highest input.

D: All mine trucks are above 240 ton (320 tons) with some exceptions for the road base
trucks which are maintenance vehicles and over 40 tons.

E: All observed trucks had 6 wheels (two front and four back wheels).

F: The waste dump lift is designed to not exceed 1000 feet, with most design heights not
exceeding 200 feet, which is audited by MSHA.

G: The surface area of the Solvent Extraction/Electrowinning Plant mixer/settlers is
calculated as 252 ft2; this unit has been shut down since 2015.

II.B.1.g The following site-wide emission limits at the BCM shall not be exceeded:

A. 7,350 tons of NOx, PM10 and SO2 combined per rolling 12-month period.

B. 6,205 tons of NOx, PM2.5 and SO2 combined per rolling 12-month period.

The owner/operator shall determine compliance with the 12-month period limits on a rolling 12-
month total per methodology outlined in Appendix A. The owner/operator shall calculate a new
12-month total by the twentieth day of each month using data from the previous 12 months.
[R307-401-8]

Status: In Compliance. These units are tracked through the Mine Management system.
Records for the 12-month period July 2022, to June 2023, are as follows:
A. NOx/SO2/PM10 emissions of 345 tons
B. NOx/SO2/PM2.5 emissions of 303 tons

II.B.1.h The owner/operator shall not operate each emergency engine on site for more than 100 hours per
rolling 12-month period during non-emergency situations. There is no time limit on the use of
the engines during emergencies. [40 CFR 60 Subpart IIII, 40 CFR 63 Subpart ZZZZ,
R307-401-8]

II.B.1.h.1 To determine compliance with a rolling 12-month total, the owner/operator shall calculate a new
12-month total by the 20th day of each month using data from the previous 12 months. Records
documenting the operation of each emergency engine shall be kept in a log and shall include the
following:

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A. The date the emergency engine was used

B. The duration of operation in hours

C. The reason for the emergency engine usage. [40 CFR 63 Subpart ZZZZ, R307-401-8]

Status: In Compliance. Emergency generators are used only during power supply
interruptions and for maintenance purposes. Use logs have been kept and indicated that no
generators operated for more than 100 hours for maintenance during the previous 12-
month period. These units are contracted to a third party.

Generator Hours
Lark Gate 0.4
#1 6.1
#2 0.9
Production Control Building 6690/ 93.8
Communications 6190
Mandy's Landing 20.4
East Side Dump 10.3
Zelnora removed
SAM Site 20.3
Substation 2 33.7
Support Generator 1 0

II.B.1.h.2 To determine the duration of operation, the owner/operator shall install a non-resettable hour
meter for each emergency engine. [40 CFR 63 Subpart ZZZZ, R307-401-8]

Status: In Compliance. All units have non-resettable hour meters installed.

II.B.2 Equipment Requirements.

II.B.2.a The Main In-Pit Crusher Baghouse shall control process streams from the Main In-Pit Crusher.
This baghouse shall be sized to handle at least 12,898 Dry Standard Cubic Feet per Minute
(DSCFM). All exhaust air from the Main In-Pit Crusher shall be routed through the baghouse
before being vented to the atmosphere. [R307-401-8]

Status: In Compliance. The Main In-Pit Crusher baghouse controls process streams from
the Main In-Pit Crusher. According to the source, the baghouse is rated for 16,800 DSCFM
from the manufacturer. All exhaust from the crusher is routed through the baghouse.

II.B.2.b The lime silos fabric bin vent control units shall control process streams from the lime silos. This
control unit shall be sized to handle at least 616 DSCFM. All exhaust air from the lime silos shall
be routed through the control unit before being vented to the atmosphere. [R307-401-8]

Status: Not Applicable. The lime silos are at the concentrator, are also listed on the
concentrator AO and are addressed in that report. However, the source stated that the lime
silo baghouses are rated to handle at least 616 DSCFM.

II.B.2.c The Controlled Transfer Drop Point C6/C7 baghouse shall control process streams from the drop
point. This baghouse shall be sized to handle at least 5,120 DSCFM. All exhaust air from the
C6/C7 transfer drop point shall be routed through the baghouse before being vented to the
atmosphere. [R307-401-8]

Status: Not Applicable. The C6/C7 Controlled Transfer Drop Point has been removed, and
is no longer in service.

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II.B.2.d The Controlled Transfer Drop Point C7/C8 baghouse shall control process streams from the drop
point. This baghouse shall be sized to handle at least 3,168 DSCFM. All exhaust air from the
C7/C8 transfer drop point shall be routed through the baghouse before being vented to the
atmosphere. [R307-401-8]

Status: In Compliance. The C7/C8 Controlled Transfer Drop Point has been renamed the
C6/C8 Controlled Transfer Drop Point. The source stated that the baghouse is rated for
7,000 ACFM from the manufacturer. All exhaust air from the C6/C8 transfer drop point is
routed through the baghouse before being vented to the atmosphere.

II.B.2.e The Sample Preparation baghouse shall control process streams from the sample preparation
building crushing and grinding equipment. This baghouse shall be sized to handle at least 4,200
DSCFM. All exhaust air from the sample preparation crusher and grinder shall be routed through
the baghouse before being vented to the atmosphere. [R307-401-8]

Status: In Compliance. The Sample Preparation baghouse controls process streams from
the sample preparation building crushing and grinding equipment. All exhaust air from the
sample preparation crusher and grinder is routed through the baghouse before being
vented to the atmosphere.

II.B.2.f The Electrowinning Acid Mist Eliminator shall control process streams from the electrowinning
cells. This mist eliminator shall be sized to handle at least 8,000 actual CFM. Except during
service, inspection, and cathode harvest, all exhaust air from the electrowinning cells shall be
routed through the mist eliminator before being vented to the atmosphere. [R307-401-8]

Status: Not Applicable. This unit has been shut down since 2015.

II.B.2.g The solvent extraction tanks and the stripping mixer/settlers shall be covered at all times except
during inspection, sampling, and adjustment. [R307-401-8]

Status: Not Applicable. These tanks are part of the Electrowinning Acid Mist Eliminator.
This unit has been shut down since 2015.

II.B.2.h The concrete batch plant baghouse shall control all process streams from the 25 cubic yard
concrete batch plant listed in Condition II.A.12. This baghouse shall be sized to handle at least
3,900 DSCFM. All exhaust air from the concrete batch plant shall be routed through the
baghouse before being vented to the atmosphere. [R307-401-8]

Status: Not Applicable. The 25 cubic yard concrete batch plant listed in Condition II.A.12
is not installed or operational.

II.B.2.i The owner/operator shall only combust diesel fuel that meets the definition of ultra-low sulfur
diesel (ULSD), which has a sulfur content of 15 ppm or less. [R307-401-8]

Status: In Compliance. A certificate of analysis provided by Sinclair indicates the fuel
meets the ULSD requirement and was reviewed during the inspection.

II.B.2.i.1 To demonstrate compliance with the ULSD fuel requirement, the owner/operator shall maintain
records of diesel fuel purchase invoices or obtain certification of sulfur content from the diesel
fuel supplier. The diesel fuel purchase invoices shall indicate that the diesel fuel meets the ULSD
requirements. [R307-401-8]

Status: In Compliance. A certificate of analysis provided by Sinclair indicates the fuel
meets the ULSD requirement and was reviewed during the inspection.

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II.B.3 Roads and Fugitive Dust.

II.B.3.a The owner/operator shall abide by a FDCP acceptable to the Director for control of all dust
sources associated with the BCM. The FDCP shall be updated and submitted on an annual basis
to the Director by February 1 of every year. This plan shall contain sufficient controls to prevent
an increase in PM10 emissions above those modeled for this AO. The haul road length, speed, or
any other parameters used to calculate the emissions cannot be changed without prior approval
from the Director, if the change would result in an increase in emissions above the limitations set
in the FDCP. [R307-309]

Status: In Compliance. Rio Tinto submitted an annual road dust control report in
conjunction with the FDCP on January 16, 2023. This plan was reviewed and found to
contain sufficient controls to prevent an increase in PM10 emissions above those modeled
for this AO. The haul road length, speed, or any other parameters used to calculate the
emissions have not changed. Refer to this document in the attachments.

II.B.3.b The BCM shall comply with all applicable requirements of UAC R307-205 and R307-309 for
Fugitive Emission and Fugitive Dust sources. The provisions of R307-205 and R307-309 shall
not apply to any sources for which limitations for fugitive dust or fugitive emissions are assigned
pursuant to R307-401 or R307-305 nor shall they apply to agricultural or horticultural activities.
[R307-309]

Status: In Compliance. The FDCP incorporates the applicable requirements of R307-205
and R307-309 for Fugitive Emission and Fugitive Dust sources.

II.B.3.c Control of disturbed or stripped areas is required at all times (24 hours per day every day) for the
duration of the project/operation until the area is reclaimed. Records of disturbed area, treatment
and/or reclamation shall be kept for all periods when the BCM is in operation. [R307-309]

Status: In Compliance. Disturbed or stripped areas are controlled at all times until the area
is reclaimed. The source currently operates eight dedicated water trucks. Magnesium
chloride is applied once a month using a hydro seeder truck for light vehicle roadways.
Surfactant is mixed into each large water truck load and applied on the haul roads.

II.B.3.d Visible fugitive dust emissions from haul-road traffic and mobile equipment in operational areas
shall not exceed 20% opacity at any point. Visible emission determinations shall use procedures
similar to Method 9. The normal requirement for observations to be made at 15-second intervals
over a six-minute period, however, shall not apply. Visible emissions shall be measured at the
densest point of the plume but at a point not less than 1/2 vehicle length behind the vehicle and
not less than 1/2 the height of the vehicle. [R307-309]

Status: In Compliance. No visible dust emissions were observed from haul-road traffic or
mobile equipment. The haul roads were visibly wet during the inspection and water trucks
were in operation throughout the mine.

II.B.3.e Water sprays, chemical dust suppression sprays or enclosures shall be installed at the following
points that are not enclosed or have baghouses to control fugitive emissions:

A. All stationary and portable conveyor transfer points
B. All portable crusher input and output points, and screening unit points or partial
enclosures.

The sprays shall operate whenever dry conditions warrant or as determined necessary by the
Director. [R307-309]

Status: In Compliance. All stationary and portable conveyor transfer points are enclosed or
controlled by baghouses. All portable crushing equipment has water sprays that are
included in Rio Tinto's preventative maintenance schedule. Additionally, the source has
water sprays installed and operating at various points along the length of the conveyor
system.

13
II.B.3.f The accessible surfaces of all uncovered storage piles shall be sprayed with water or chemical
dust suppressants to minimize generation of fugitive dusts, as dry conditions warrant or as
determined necessary by the Director. Records of water and/or chemical dust control treatment
shall be kept for all periods when the plant is in operation. [R307-309]

Status: In Compliance. The source sprays uncovered storage piles as necessary to control
fugitive dust. Records of watering have been kept. No emissions of fugitive dust were
observed from any storage pile during this inspection.

II.B.3.g The opacity on active waste slopes shall not exceed 20%. Opacity observations shall be
conducted in accordance with 40 CFR 60, Appendix A, Method 9, but the requirement for
observations to be made at 15-second intervals over a six-minute period shall not apply. At any
time, the owner/operator may propose a compliance method to UDAQ for approval prior to
implementation. [R307-309]

Status: In Compliance. The source has performed and recorded monthly opacity
observations at the active dump faces. No emissions were observed during the inspection
from any waste slopes.

II.B.3.h The owner/operator shall use frequent watering or chemical dust suppressant to control road dust
from all trafficked roads and areas in the mine. The owner/operator shall submit an annual road
dust control report, in conjunction with the FDCP, by February 1 of each calendar year,
containing as a minimum the following:

A. A description of what dust control measures are planned for the coming year

B. A report of what dust control measures were actually completed during the past year

C. Specific elements of the report will include:

1) A map of all trafficked areas and roads associated with the mine, indicating
which areas are planned for water and/or chemical dust suppressant treatment.

2) A description of the chemical dust suppressant and how it will be
applied (application rate, application frequency, dilution rate, special
application procedure, scarification, etc.).

3) A list of equipment dedicated either full or part time to the work area and
for road dust control (number of water trucks, water capacity, number
of graders, etc.).

4) A quantification of how much dust suppressant (gallons, tons) was
applied the previous year and when and where it was applied.

5) A quantification of how much watering was accomplished the previous
year (gallons, water truck operating hours).

6) A map outlining the pit influence boundary. [R307-309]

Status: In Compliance. Rio Tinto uses MgCl2 and has seven dedicated water trucks which
operate daily in order to control dust. Rio Tinto submitted an annual road dust control
report in conjunction with the FDCP on January 16, 2023. This report has been reviewed
for accuracy and is included in the attachments. No excess emissions were noted during this
inspection. All roads appeared to be moist and dust was controlled.

II.B.3.i Wet drilling shall be performed for all blast holes. [R307-309]

Status: In Compliance. All drills are equipped with water to control fugitive dust emissions
during operation. No drilling was observed during this inspection.

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II.B.3.j To minimize fugitive dust on roads at the BCM, the owner/operator shall perform the following
measures:

A. Apply water to all active haul roads located at the BCM as conditions warrant and in
accordance with the FDCP, and shall

1) ensure the surface of the active haul roads located within the pit influence
boundary consists of road base material, blasted waste rock, crushed rock,
or chemical dust suppressant, and

2) apply a chemical dust suppressant to active haul roads located outside
of the pit influence boundary no less than twice per year.

B. Ore conveyors shall be the primary means for transport of crushed ore from the
BCM to the Copperton Concentrator.

C. Chemical dust suppressant shall be applied on unpaved access roads that receive
haul truck traffic and light vehicle traffic as defined in the FDCP.

D. The owner/operator shall use graders to perform haul road maintenance and clean-up
activities as well as other operational functions. [R307-309-10]

E. If, for a 12-month period, the material movement by haul trucks is below 197,000,000
tpy of ore and waste rock combined, the owner/operator may petition the Director to
revise the fugitive dust control measures above. [R307-309-10]

Status: In Compliance. Ore conveyors are the primary means of transporting crushed ore
from the BCM to the Copperton Concentrator. Grader hours of operation and road base
crusher throughput are recorded to demonstrate that applicable haul roads are being
covered with road base and crushed rock. MgCl2 and surfactant are added into water
loads. Dedicated haul trucks apply water to all active haul roads as conditions warrant and
in accordance with the FDCP. All road surfaces appeared to be wet and no excess dust was
noted due to traffic. Water trucks were in use during this inspection.

II.B.4 Monitoring Requirements.

II.B.4.a The owner/operator shall operate two ambient monitoring stations to monitor PM10 in Copperton
and lower Butterfield Canyon area as approved by the Director. The monitoring plan will be
periodically reviewed and revised as necessary. Any changes must be approved by the Director.

The air monitoring stations shall remain in operation, at a minimum, until the BCM material
moved has achieved a minimum of 234,000,000 TPY. If after that amount of material moved has
been achieved and monitoring data indicates compliance with the NAAQS, the owner/operator
may petition the Director to remove the air monitoring stations. [R307-410]

Status: In Compliance. Both monitoring stations were in existence pre-dating this AO. See
Conditions below for compliance requirement details. The two stations are listed on the
ambient monitoring report as Copperton C3 and High-Country sites.

II.B.4.b The owner/operator shall utilize federal reference method (FRM) or federal equivalent method
PM10 monitors as specified in 40 CFR 53 and quality assurance procedures which are equal to or
exceed the requirements described in the EPA Quality Assurance Manual including revisions, 40
CFR Parts 50, 53 and 58. [R307-410]

Status: In Compliance. Rio Tinto utilizes federal reference method (FRM) or federal
equivalent method PM10 monitors as specified in 40 CFR 53 and quality assurance
procedures which are equal to or exceed the requirements described in the EPA Quality
Assurance Manual including revisions, 40 CFR Parts 50, 53, and 58. A contractor (Trinity
Consultants) performs independent audits quarterly, and results of these audits have been
submitted to DAQ for review. Reports are in the main source files.

15
II.B.4.c If the PM10 concentrations measured are greater than 135 ug/m3 (90% of the 24-hr PM10
NAAQS) and if such concentrations have been measured for more than one day per year on an
average over three consecutive years, the owner/operator shall conduct a review of mine
operations and other potential sources and conditions such as the Natural Events Exception
Criteria.

If it is determined the BCM may be the source of the elevated ambient PM10 concentrations, the
owner/operator shall work with DAQ to review control practices and possible changes in
practices to avoid future elevated concentrations. [R307-410]

Status: In Compliance. Measured PM10 concentrations have not been greater than
135µg/m3 for more than one day per year on an average over three consecutive years. Data
summaries are reported to DAQ in quarterly and annual independent auditor reports. All
reports are reviewed by DAQ staff and are in the main source files.

II.B.4.d The owner/operator shall submit quarterly data reports within 45 days after the end of the
calendar quarter and an annual data report within 90 days after the end of the calendar year.

The quarterly report shall consist of a narrative data summary and a submittal of all data points in
EPA-AIRS record format. The data shall be submitted on a compact disk (CD). The narrative
data summary shall include:

A. A topographic map of appropriate scale with UTM coordinates and a true north arrow
showing the air monitoring site locations in relation to the mine and the general area;

B. A hard copy of the individual data points;

C. The quarterly and monthly arithmetic means for PM10 at actual temperature and
pressure;

D. The first and second highest 24-hour concentrations for PM10;

E. The quarterly and monthly wind roses;

F. A summary of the data collection completeness;

G. A summary of the reasons for missing data;

H. An audit summary;

I. A summary of any ambient air PM10 exceedances;

J. Calibration information; and

K. Laboratory reports (for exceedance filters).

The annual data report shall consist of a narrative data summary containing:

A. A topographic map of appropriate scale with UTM coordinates and a true north arrow
showing the air monitoring site locations in relation to the mine and the general area;

B. A pollution trend analysis;

C. The annual arithmetic means for PM10;

D. The first and second highest 24-hour concentrations for PM10;

E. The annual wind rose;

F. Annual summaries of data collection frequency and completeness;

16
G. An annual summary of audit data;

H. An annual summary of any ambient standard exceedance;

I. Annual mine material moved in TPY;

J. Annual summary of analytical speciation results for detectible metals (for exceedance
filters); and

K. Recommendations on future monitoring.

The Director may audit the air monitoring network, the laboratory performing associated
analysis, and any data handling procedures at unspecified times. On the basis of the audits and
subsequent reports, DAQ may recommend or require changes in the air monitoring system and
associated activities in order to improve data quality and completeness. [R307-410]

Status: In Compliance. Rio Tinto has submitted quarterly and annual data reports
containing the information required by this condition. These reports have been reviewed
for accuracy and are contained in DAQ's source files.

II.B.4.e The owner/operator shall contract with an independent firm to conduct quarterly performance
audits of its PM10 monitors.

Exposed PM10 filters that exceed 150 ug/m3 shall be analyzed for metals, and other constituents
as requested by the Director. One filter blank per batch of ten filters or less shall also be
submitted for analysis. [R307-410]

Status: In Compliance. Rio Tinto has contracted with an independent firm (Trinity
Consultants) to conduct quarterly performance audits of its PM10 monitors. Audit results
have been submitted to the DAQ in quarterly data reports. Additional analysis for metals
and other constituents has not been necessary.

II.B.4.f PM10 and meteorological data (wind speed, wind direction, and ambient temperature) shall be
collected at each site. The meteorological tower shall be located within one mile of the monitor
station. [R307-410]

Status: In Compliance. PM10 and meteorological data (wind speed, wind direction, and
ambient temperature) is collected at the sites. Rio Tinto reports summary data in quarterly
data reports. These reports are submitted to and reviewed by DAQ. Reports are in the
main source files.

UTAH STATE IMPLEMENTATION PLAN (SIP)
g. Kennecott Utah Copper (KUC): Mine

i. Bingham Canyon Mine (BCM)

A. Maximum total mileage per calendar day for diesel-powered ore and waste haul trucks
shall not exceed 30,000 miles.

KUC shall keep records of daily total mileage for all periods when the mine is in
operation. KUC shall track haul truck miles with a Global Positioning System or
equivalent. The system shall use real time tracking to determine daily mileage.
B. To minimize fugitive dust on roads at the mine, the owner/operator shall perform the
following measures:

I. Apply water to all active haul roads as weather and operational conditions warrant
except during precipitation or freezing weather conditions, and shall apply a
17
chemical dust suppressant to active haul roads located outside of the pit influence
boundary no less than twice per year.

II. Chemical dust suppressant shall be applied as weather and operational conditions
warrant except during precipitation or freezing weather conditions on unpaved
access roads that receive haul truck traffic and light vehicle traffic.

III. Records of water and/or chemical dust control treatment shall be kept for all
periods when the BCM is in operation.

IV. KUC is subject to the requirements in the most recent federally approved Fugitive
Emissions and Fugitive Dust rules.

C. To minimize emissions at the mine, the owner/operator shall:

I. Control emissions from the in-pit crusher with a baghouse.

Status: In Compliance. All requirements of this SIP have been incorporated into the
AO conditions above and are reported under those conditions.

Section III: APPLICABLE FEDERAL REQUIREMENTS

In addition to the requirements of this AO, all applicable provisions of the following federal programs
have been found to apply to this installation. This AO in no way releases the owner or operator from any
liability for compliance with all other applicable federal, state, and local regulations including UAC
R307.

NSPS (Part 60) -LL : Standards of performance for Metallic Mineral Processing Plants

Status: In Compliance. According to previous inspection memos initial observations of the main pit
crusher baghouse and other metallic mineral processing equipment occurred on July 1, 1993. No
fugitive emissions greater than 10 percent opacity were observed during the inspection. The main in-pit
crusher is required to be stack tested and is limited to 0.016 gr/dscf PM which is less than the 0.0218
gr/dscf (0.05 g/dscm) limit in subpart LL. The main in-pit crusher was last stack tested on October 29,
2021, and the result was 0.0038 gr/dscf (DAQC-005-22).

According to previous inspection memos initial observations of the main pit crusher baghouse and other
metallic mineral processing equipment occurred on July 1, 1993.

NSPS (Part 60) -IIII : Standards of Performance for Stationary Compression Ignition Internal Combustion
Engines

Status: In Compliance. The 2,250 kW Diesel generator is applicable this subpart. The generator has the
required certificate and is operated in accordance with manufacturer maintenance requirements. The
engine has a non-resettable hour meter and all hours, reason for firing, and maintenance activities are
logged. This engine did not operate in excess of 100 non-emergency hours during the previous 12 month
period. Yearly maintenance is done and includes all the required items. Only ultra-low sulfur fuel is
ordered for this unit.

18
NSPS (Part 60) -JJJJ : Standards of Performance for Stationary Spark Ignition Internal Combustion Engines

Status: In Compliance. The units applicable to this subpart are the LPG engines newer than 2009 as
listed above. All units have the required certifications. All engines follow the manufacturer maintenance
requirements. All units have non-resettable hour meters and none have exceeded 100 hours of non-
emergency operations in the past 12-month period. Records are kept of hours, reasons for use, and any
maintenance activities. No exceedance of hours or other compliance issues have occurred.

NSPS (Part 60) -OOO : Standards of Performance for Nonmetallic Mineral Processing Plants

Status: In Compliance. An initial performance test was conducted on the road-base crushing operation
on July 16, 2018 (DAQC-2018-013021). Only minimal opacity was observed during the inspection.

MACT (Part 63) -ZZZZ : National Emissions Standards for Hazardous Air Pollutants for Stationary
Reciprocating Internal Combustion Engines

Status: In Compliance. This federal requirement is satisfied through compliance with NSPS Subpart
IIII and NSPS Subpart JJJJ.

AREA SOURCE RULES EVALUATION:

The following Area Source Rules were evaluated during this inspection:

Nonattainment and Maintenance Areas for PM10:Emissions and Fugitive Emissions and Fugitive Dust
[R307-309]

Status: In Compliance. The source operates with a FDCP that is updated yearly. Water trucks
operate as needed to control dust, and chemical suppressants are applied throughout the year as
needed. See applicable fugitive dust emissions conditions in the AO for more detail. No fugitive dust
was observed during the inspection.

Aggregate Processing Operations for PM2.5 Nonattainment Areas [R307-312]

Status: In Compliance. The source is required to maintain the opacity limits listed in R307-312,
however the limits in NSPS subpart LL are lower than the limits in R307-312. Only minimal fugitive
emissions were observed from the aggregate processing equipment. See the applicable opacity
conditions in the AO for more detail.

National Emission Standards for Hazardous Air Pollutants [R307-214]

Status: In Compliance. This rule is satisfied through compliance with MACT Subpart ZZZZ. Refer
to the Federal Requirements section for more details.

Davis and Salt Lake Counties and Ozone Nonattainment Areas: Ozone Provisions [R307-325]

Status: In Compliance. No VOC's were observed to be spilled, stored in open contains, or handled in
any other manner that would result in greater evaporation of VOCs than would have if reasonably
available control technology had been applied.

19
Degreasing and Solvent Cleaning Operations [R307-335]

Status: In Compliance. The source has several degreasers for cleaning hand tools within the truck
shop. The degreasers are kept closed, written procedures are posted on the degreasers, no uncovered
waste containers were observed, the equipment appeared to be maintained in good operating
condition, and no leaks or spills were observed at any of the degreasers.

EMISSION INVENTORY:

Listed before are the 2022 Actual Emissions Inventory provided from Rio Tinto Kennecott Utah Copper
LLC - Mine & Copperton Concentrator. A comparison of the estimated total potential emissions (PTE) on
AO: DAQE-AN105710047-21, dated May 10, 2021, is provided.
PTE are supplied for supplemental purposes only.

Criteria Pollutant PTE tons/yr Actuals tons/yr
CO2 Equivalent 8320.18 N/A
Carbon Monoxide 1707.70 6.751
Nitrogen Oxides 5842.11 4.757
Particulate Matter - PM10 1519.21 679.4
Particulate Matter - PM2.5 369.21 82.84
Sulfur Dioxide 7.43 0.023
Volatile Organic Compounds 314.13 4.397

Hazardous Air Pollutant PTE lbs/yr Actuals lbs/yr
Total HAPs (CAS #THAPS) 3480 N/A

PREVIOUS ENFORCEMENT
ACTIONS: Compliance Advisory (DAQC-015-22) and Early Settlement
Agreement (DAQC-134-22) for stack testing exceedances on the
C6/C8 Transfer Point Baghouse.

COMPLIANCE STATUS &
RECOMMENDATIONS: In regards to Approval Order (AO) DAQE-AN105710047-21,
dated May 10, 2021: In Compliance. The source appears to be
well maintained and operated. Required records were current and
made available during the inspection.

HPV STATUS: Not Applicable.

RECOMMENDATION FOR
NEXT INSPECTION: Inspect at the regular inspection frequency for this type of
source. Long-sleeved shirt, hard hat, steel-toed boots, and
hearing protection are required for the inspection. Gloves will be
helpful if you will be inspecting the Concentrator when touring
the molybdenum processing areas. A short safety video is
required to access the site. Contact the environmental contact
prior to the inspection as additional staff at the source will be
required to tour the facilities.

ATTACHMENTS: None.