DAQ-2024-011943

DAQE-AN121040008-24

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Mike Busch
Rocky Mountain Machine Shop Inc.
PO Box 25006
Salt Lake City, UT 84125
[e-mail]

Dear Mr. Busch:

Re: Approval Order: Administrative Amendment to Approval Order DAQE-AN0121040007-09 for a
10-Year Review and Permit Updates
Project Number: N121040008

The attached Approval Order (AO) is issued pursuant to the Division of Air Quality conducting a
10-year administrative review of this source and its respective AO. Rocky Mountain Machine Shop
Inc. must comply with the requirements of this AO, all applicable state requirements (R307), and Federal
Standards.

The project engineer for this action is Katie Andersen, who can be contacted at [phone] or
[e-mail]. Future correspondence on this AO should include the engineer's name as well as
the DAQE number shown on the upper right-hand corner of this letter.

Sincerely,

{{$s }}

Bryce C. Bird
Director

BCB:KA:jg

cc: Salt Lake County Health Department

195 North 1950 West • Salt Lake City, UT
Mailing Address: P.O. Box 144820 • Salt Lake City, UT 84114-4820
Telephone [phone] • Fax [phone] • T.D.D. [phone]
www.deq.utah.gov
Printed on 100% recycled paper
State of Utah

SPENCER J. COX
Governor
DEIDRE HENDERSON
Lieutenant Governor

Department of
Environmental Quality

Kimberly D. Shelley
Executive Director

DIVISION OF AIR QUALITY
Bryce C. Bird
Director

December 5, 2024

STATE OF UTAH
Department of Environmental Quality
Division of Air Quality

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APPROVAL ORDER
DAQE-AN121040008-24
Administrative Amendment to Approval Order
DAQE-AN0121040007-09 for a 10-Year Review
and Permit Updates

Prepared By
Katie Andersen, Engineer
[phone]
[e-mail]

Issued to
Rocky Mountain Machine Shop Inc. - Salt Lake City Machine Shop

Issued On
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Issued By

{{$s }}

Bryce C. Bird
Director
Division of Air Quality

December 5, 2024
TABLE OF CONTENTS

TITLE/SIGNATURE PAGE ....................................................................................................... 1
GENERAL INFORMATION ...................................................................................................... 3
CONTACT/LOCATION INFORMATION ............................................................................... 3
SOURCE INFORMATION ........................................................................................................ 3
General Description ................................................................................................................ 3
NSR Classification .................................................................................................................. 3
Source Classification .............................................................................................................. 3
Applicable Federal Standards ................................................................................................. 3
Project Description.................................................................................................................. 4
SUMMARY OF EMISSIONS .................................................................................................... 4
SECTION I: GENERAL PROVISIONS .................................................................................... 4
SECTION II: PERMITTED EQUIPMENT .............................................................................. 5
SECTION II: SPECIAL PROVISIONS ..................................................................................... 5
PERMIT HISTORY ..................................................................................................................... 7
ACRONYMS ................................................................................................................................. 8

DAQE-AN121040008-24
Page 3

GENERAL INFORMATION

CONTACT/LOCATION INFORMATION

Owner Name Source Name
Rocky Mountain Machine Shop Inc. Rocky Mountain Machine Shop Inc. - Salt Lake City Machine Shop

Mailing Address Physical Address
PO Box 25006 1165 South Pioneer Road
Salt Lake City, UT 84125 Salt Lake City, UT 84104

Source Contact UTM Coordinates
Name: Mike Busch 419,171 m Easting
Phone: [phone],510,786 m Northing
Email: [e-mail] Datum NAD83
UTM Zone 12
SIC code 3549 (Metalworking Machinery, NEC)

SOURCE INFORMATION
General Description
Rocky Mountain Machine Shop Inc. (RMMS) owns and operates an industrial machine service and
metalwork fabrication plant in Salt Lake City, Salt Lake County. RMMS refurbishes and services
defective, corroded, or nicked drive shafts and hydraulic cylinders from heavy machinery. Items are
received in the plant and prepared by removing the defective plating. The items are then cleaned with
solvents and prepared for plating. Three (3) 5,000-amp, two (2) 8,000-amp, and one (1) 10,000-amp
rectifiers support the electrochemical plating process of depositing chromium oxide to a base metal via
the appropriate electrolyte. The source is categorized as a large, hard chromium (Cr) electroplating
facility.
NSR Classification
10-Year Review

Source Classification
Located in Northern Wasatch Front O3 NAA, Salt Lake City UT PM2.5 NAA, Salt Lake County SO2
NAA
Salt Lake County
Airs Source Size: B

Applicable Federal Standards
MACT (Part 63), A: General Provisions
MACT (Part 63), N: National Emission Standards for Chromium Emissions From Hard and
Decorative Chromium Electroplating and Chromium Anodizing Tanks
DAQE-AN121040008-24
Page 4

Project Description
This is a 10-Year Review to update the format, language, and layout of the AO to match current DAQ
permitting standards.

SUMMARY OF EMISSIONS

The emissions listed below are an estimate of the total potential emissions from the source. Some
rounding of emissions is possible.

Criteria Pollutant Change (TPY) Total (TPY)
Carbon Monoxide 0 0.48
Nitrogen Oxides 0 0.11
Volatile Organic Compounds 0 20.00

Hazardous Air Pollutant Change (lbs/yr) Total (lbs/yr)
Generic HAPs (CAS #GHAPS) 0 12000
Hexane (CAS #110543) 0 18000
Change (TPY) Total (TPY)
Total HAPs 0 15.00

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]
DAQE-AN121040008-24
Page 5

I.6 The owner/operator shall comply with UAC R307-107. General Requirements: Breakdowns. [R307-107] I.7 The owner/operator shall comply with UAC R307-150 Series. Emission Inventories. [R307-150]

SECTION II: PERMITTED EQUIPMENT
II.A THE APPROVED EQUIPMENT
II.A.1 Machine Shop Industrial machine service and metalwork fabrication plant. II.A.2 Chrome plating tanks Six (6) chrome plating tanks
II.A.3 Surface preparation Preparation of various metal parts for chrome plating or painting II.A.4 Surface coating Painting of various metal parts
II.A.5 Welding II.A.6 Mist eliminator Horizontal mist eliminator, attached to the chrome plating tanks, 12,000 acfm
II.A.7 Paint booth DB-108 12' x 6' x 7'8", 12,000 cfm, 30" diameter stack, particulate arrestor filters II.A.8 Various Heaters Rating: less than 5 MMBtu/hr each Fuel: Natural Gas Rating: Less than 0.5 MMBtu/hr each Fuel: Hydraulic Oil or Used Oil Listed for informational purposes only.

SECTION II: SPECIAL PROVISIONS
II.B REQUIREMENTS AND LIMITATIONS
II.B.1 The Machine Shop shall be subject to the following: II.B.1.a The owner/operator shall not allow visible emissions from any stationary point or fugitive emission source associated with the source or with the control facilities to exceed 10% opacity. [R307-401-8]
II.B.1.a.1 Opacity observations of emissions from stationary sources shall be conducted in accordance with 40 CFR 60 Appendix A, Method 9. [R307-401-8]
DAQE-AN121040008-24
Page 6

II.B.2 VOC & HAP Requirements II.B.2.a The owner/operator shall not emit more than the following from evaporative sources (painting,
printing, coating, and/or cleaning) on site: 20.00 tons per rolling 12-month period of VOCs
9.00 tons per rolling 12-month period of hexane (HAP) 6.00 tons per rolling 12-month period combined for xylene, toluene, and methanol.
[R307-401-8]
II.B.2.a.1 The owner/operator shall calculate a new 12-month total by the 20th day of each month using data from the previous 12 months. The owner/operator shall use a mass-balance method to calculate emissions from evaporative sources. The owner/operator may use the following equations with applicable units to comply with the mass-balance method: VOCs = [% VOCs by Weight/100] x [Density] x [Volume Consumed] HAP = [% HAP by Weight/100] x [Density] x [Volume Consumed] [R307-401-8]
II.B.2.a.2 The owner/operator shall use a mass-balance method to quantify any amount of VOCs and HAPs reclaimed. The owner/operator shall subtract the amount of VOCs and HAPs reclaimed from the
quantities calculated above to provide the monthly total emissions of VOCs and HAPs.
[R307-401-8]
II.B.2.a.3 The owner/operator shall keep records each month of the following: A. The name of the VOC- and HAP-emitting material, such as paint, adhesive, solvent, thinner, reducers, chemical compounds, toxics, isocyanates, etc. B. The maximum percent by weight of VOCs and each HAP in each material used C. The density of each material used D. The volume of each VOC- and HAP-emitting material used E. The amount of VOCs and the amount of each HAP emitted from each material F. The amount of VOCs and the amount of each HAP reclaimed and/or controlled from each material G. The total amount of VOCs, the total amount of each HAP, and the total amount of all HAPs combined emitted from all materials (in tons) H. The VOC or HAP emissions from the fuel-burning devices (products of incomplete combustion) are not included in the above total. [R307-401-8]
II.B.2.b The owner/operator shall comply with the applicable requirements of R307-350: Miscellaneous
Metal Parts and Products Coatings. [R307-350]

II.B.2.c The owner/operator shall comply with the applicable requirements of 40 CFR 63 Subpart N: National Emission Standards for Chromium Emissions from Hard and Decorative Chromium Electroplating and Chromium Anodizing Tanks. [40 CFR 63 Subpart N]

DAQE-AN121040008-24
Page 7

PERMIT HISTORY

This Approval Order shall supersede (if a modification) or will be based on the following documents: Supersedes AO DAQE-AN0121040007-09 dated April 9, 2009

DAQE-AN121040008-24
Page 8

ACRONYMS

The following lists commonly used acronyms and associated translations as they apply to this document:

40 CFR Title 40 of the Code of Federal Regulations
AO Approval Order
BACT Best Available Control Technology
CAA Clean Air Act
CAAA Clean Air Act Amendments
CDS Classification Data System (used by Environmental Protection Agency to classify
sources by size/type)
CEM Continuous emissions monitor
CEMS Continuous emissions monitoring system
CFR Code of Federal Regulations
CMS Continuous monitoring system
CO Carbon monoxide
CO2 Carbon Dioxide
CO2e Carbon Dioxide Equivalent - Title 40 of the Code of Federal Regulations Part 98,
Subpart A, Table A-1
COM Continuous opacity monitor
DAQ/UDAQ Division of Air Quality
DAQE This is a document tracking code for internal Division of Air Quality use
EPA Environmental Protection Agency
FDCP Fugitive dust control plan
GHG Greenhouse Gas(es) - Title 40 of the Code of Federal Regulations 52.21 (b)(49)(i)
GWP Global Warming Potential - Title 40 of the Code of Federal Regulations Part 86.1818-
12(a)
HAP or HAPs Hazardous air pollutant(s)
ITA Intent to Approve
LB/YR Pounds per year MACT Maximum Achievable Control Technology MMBTU Million British Thermal Units NAA Nonattainment Area NAAQS National Ambient Air Quality Standards NESHAP National Emission Standards for Hazardous Air Pollutants NOI Notice of Intent
NOx Oxides of nitrogen
NSPS New Source Performance Standard
NSR New Source Review
PM10 Particulate matter less than 10 microns in size
PM2.5 Particulate matter less than 2.5 microns in size
PSD Prevention of Significant Deterioration
PTE Potential to Emit
R307 Rules Series 307
R307-401 Rules Series 307 - Section 401
SO2 Sulfur dioxide
Title IV Title IV of the Clean Air Act
Title V Title V of the Clean Air Act
TPY Tons per year
UAC Utah Administrative Code
VOC Volatile organic compounds

DAQE-
RN121040008 December 2, 2024 Mike Busch Rocky Mountain Machine Shop Inc. PO Box 25006 Salt Lake City, UT 84125-0006 [e-mail] Dear Mike Busch, Re: Engineer Review: Administrative Amendment to Approval Order DAQE-AN0121040007-09 dated April 9, 2009, for a 10-Year Review and Permit Updates Project Number: N121040008 The DAQ requests a company representative review and sign the attached Engineer Review (ER). This ER identifies all applicable elements of the New Source Review (NSR) permitting program. Rocky Mountain Machine Shop Inc. should complete this review within 10 business days of receipt. Rocky Mountain Machine Shop Inc. should contact Katie Andersen at [phone] if there are questions or concerns with the review of the draft permit conditions. Upon resolution of your concerns, please email Katie Andersen at [e-mail] the signed cover letter. Upon receipt of the signed cover letter, the DAQ will prepare an Approval Order (AO) for signature by the DAQ Director. If Rocky Mountain Machine Shop Inc. does not respond to this letter within 10 business days, the project will move forward without source concurrence. If Rocky Mountain Machine Shop Inc. has concerns that cannot be resolved and the project becomes stagnant, the DAQ Director may issue an Order prohibiting construction. Approval Signature _____________________________________________________________ (Signature & Date)
195 North 1950 West • Salt Lake City, UT
Mailing Address: P.O. Box 144820 • Salt Lake City, UT 84114-4820
Telephone [phone] • Fax [phone] • T.D.D. [phone] www.deq.utah.gov Printed on 100% recycled paper
Department of Environmental Quality
Kimberly D. Shelley Executive Director DIVISION OF AIR QUALITY Bryce C. Bird Director
State of Utah
SPENCER J. COX Governor DEIDRE HENDERSON Lieutenant Governor

Engineer Review N121040008: Rocky Mountain Machine Shop Inc.- Salt Lake City Machine Shop December 2, 2024 Page 1
UTAH DIVISION OF AIR QUALITY ENGINEER REVIEW
SOURCE INFORMATION Project Number N121040008 Owner Name Rocky Mountain Machine Shop Inc. Mailing Address PO Box 25006 Salt Lake City, UT, 84125-0006 Source Name Rocky Mountain Machine Shop Inc.- Salt Lake City Machine Shop Source Location 1165 South Pioneer Road Salt Lake City, UT 84104 UTM Projection 419,171 m Easting, 4,510,786 m Northing UTM Datum NAD83 UTM Zone UTM Zone 12 SIC Code 3549 (Metalworking Machinery, NEC) Source Contact Mike Busch Phone Number [phone] Email [e-mail] Billing Contact Mike Busch Phone Number [phone] Email [e-mail] Project Engineer Katie Andersen, Engineer Phone Number [phone] Email [e-mail] Notice of Intent (NOI) Submitted July 8, 2024 Date of Accepted Application August 8, 2024

Engineer Review N121040008: Rocky Mountain Machine Shop Inc.- Salt Lake City Machine Shop December 2, 2024 Page 2
SOURCE DESCRIPTION General Description Rocky Mountain Machine Shop (RMMS) owns and operates an industrial machine service and metalwork fabrication plant in Salt Lake City, Salt Lake County. RMMS refurbishes and services defective, corroded, or nicked drive shafts and hydraulic cylinders from heavy machinery. Items are received in the plant and prepared by removing the defective plating. The items are then cleaned with solvents and prepared for plating. Three (3) 5,000 amps, two (2) 8,000 amps, and one (1) 10,000 amp rectifiers support the electrochemical plating process of depositing chromium oxide to a base metal via the appropriate electrolyte. The source is categorized as a large, hard chromium (Cr) electroplating facility. NSR Classification: 10 Year Review Source Classification Located in the Northern Wasatch Front O3 NAA, Salt Lake City UT PM2.5 NAA, and Salt Lake County SO2 NAA Salt Lake County Airs Source Size: B Applicable Federal Standards MACT (Part 63), A: General Provisions MACT (Part 63), N: National Emission Standards for Chromium Emissions From Hard and Decorative Chromium Electroplating and Chromium Anodizing Tanks Project Proposal Administrative Amendment to Approval Order DAQE-AN0121040007-09 dated April 9, 2009, for a 10-Year Review and Permit Updates Project Description This is a 10-Year Review to update the format, language, and layout of the AO to match current DAQ permitting standards. EMISSION IMPACT ANALYSIS This is a 10-Year Review. There are no changes to the emissions. The equipment list has been updated to include exempted equipment under R307-401-10 or R307-401-14. Therefore, modeling is not required at this time. [Last updated October 29, 2024]

Commented [KA1]: Remove redundant section when generating document.

Engineer Review N121040008: Rocky Mountain Machine Shop Inc.- Salt Lake City Machine Shop December 2, 2024 Page 3
SUMMARY OF EMISSIONS The emissions listed below are an estimate of the total potential emissions from the source. Some rounding of emissions is possible. Criteria Pollutant Change (TPY) Total (TPY)
Carbon Monoxide 0 0.48
Nitrogen Oxides 0 0.11 Volatile Organic Compounds 0 20.00 Hazardous Air Pollutant Change (lbs/yr) Total (lbs/yr)
Generic HAPs (CAS #GHAPS) 0 12000 Hexane (CAS #110543) 0 18000 Change (TPY) Total (TPY) Total HAPs 0 15.00
Note: Change in emissions indicates the difference between previous AO and proposed modification.

Engineer Review N121040008: Rocky Mountain Machine Shop Inc.- Salt Lake City Machine Shop December 2, 2024 Page 4
Review of BACT for New/Modified Emission Units 1. BACT review regarding 10-Year Review. This is a 10-Year Review. There are no changes to the emissions. The equipment list has been updated to include exempted equipment under R307-401-10. Therefore, a BACT analysis is not required. [Last updated October 29, 2024]
SECTION I: GENERAL PROVISIONS The intent is to issue an air quality AO authorizing the project with the following recommended conditions and that failure to comply with any of the conditions may constitute a violation of the AO. (New or Modified conditions are indicated as “New” in the Outline Label): 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 UAC R307-107. General Requirements: Breakdowns. [R307-107]
I.7 The owner/operator shall comply with UAC R307-150 Series. Emission Inventories. [R307-150]

Engineer Review N121040008: Rocky Mountain Machine Shop Inc.- Salt Lake City Machine Shop December 2, 2024 Page 5
SECTION II: PERMITTED EQUIPMENT The intent is to issue an air quality AO authorizing the project with the following recommended conditions and that failure to comply with any of the conditions may constitute a violation of the AO. (New or Modified conditions are indicated as “New” in the Outline Label): II.A THE APPROVED EQUIPMENT II.A.1 Machine Shop Industrial machine service and metalwork fabrication plant.
II.A.2 Chrome plating tanks Six (6) chrome plating tanks
II.A.3 Surface preparation Preparation of various metal parts for chrome plating or painting II.A.4 Surface coating Painting of various metal parts II.A.5 Welding II.A.6 Mist eliminator Horizontal mist eliminator, attached to the chrome plating tanks, 12,000 acfm II.A.7 Paint booth DB-108 12' x 6' x 7'8", 12,000 cfm, 30" diameter stack, particulate arrestor filters II.A.8 NEW Various Heaters Rating: less than 5 MMBtu/hr each Fuel: Natural Gas Rating: less than 0.5 MMbtu/hr each Fuel: Hydraulic Oil, or Used Oil Listed for informational purposes only.
SECTION II: SPECIAL PROVISIONS The intent is to issue an air quality AO authorizing the project with the following recommended conditions and that failure to comply with any of the conditions may constitute a violation of the AO. (New or Modified conditions are indicated as “New” in the Outline Label): II.B REQUIREMENTS AND LIMITATIONS II.B.1 NEW The Machine Shop shall be subject to the following:

Engineer Review N121040008: Rocky Mountain Machine Shop Inc.- Salt Lake City Machine Shop December 2, 2024 Page 6
II.B.1.a NEW The owner/operator shall not allow visible emissions from any stationary point or fugitive emission source associated with the source or with the control facilities to exceed 10% opacity. [R307-401-8] II.B.1.a.1 NEW Opacity observations of emissions from stationary sources shall be conducted in accordance with 40 CFR 60 Appendix A, Method 9. [R307-401-8] II.B.2 NEW VOC & HAP Requirements
II.B.2.a NEW The owner/operator shall not emit more than the following from evaporative sources (painting, printing, coating, and/or cleaning) on site: 20.00 tons per rolling 12-month period of VOCs 9.00 tons per rolling 12-month period of hexane (HAP) 6.00 tons per rolling 12-month period combined for: xylene, toluene, methanol. [R307-401-8] II.B.2.a.1 NEW The owner/operator shall calculate a new 12-month total by the 20th day of each month using data from the previous 12 months. The owner/operator shall use a mass-balance method to calculate emissions from evaporative sources. The owner/operator may use the following equations with applicable units to comply with the mass-balance method: VOCs = [% VOCs by Weight/100] x [Density] x [Volume Consumed] HAP = [% HAP by Weight/100] x [Density] x [Volume Consumed] [R307-401-8] II.B.2.a.2 NEW The owner/operator shall use a mass-balance method to quantify any amount of VOCs and HAPs reclaimed. The owner/operator shall subtract the amount of VOCs and HAPs reclaimed from the quantities calculated above to provide the monthly total emissions of VOCs and HAPs. [R307-401-8]

Engineer Review N121040008: Rocky Mountain Machine Shop Inc.- Salt Lake City Machine Shop December 2, 2024 Page 7
II.B.2.a.3 NEW The owner/operator shall keep records each month of the following: A. The name of the VOC- and HAP-emitting material, such as: paint, adhesive,
solvent, thinner, reducers, chemical compounds, toxics, isocyanates, etc. B. The maximum percent by weight of VOCs and each HAP in each material used C. The density of each material used
D. The volume of each VOC- and HAP-emitting material used E. The amount of VOCs and the amount of each HAP emitted from each material F. The amount of VOCs and the amount of each HAP reclaimed and/or controlled from each material
G. The total amount of VOCs, the total amount of each HAP, and the total amount of all
HAPs combined emitted from all materials (in tons) H. The VOC or HAP emissions from the fuel burning devices (products of incomplete
combustion) are not included in the above total. [R307-401-8]
II.B.2.b NEW The owner/operator shall comply with the applicable requirements of R307-350: Miscellaneous Metal Parts and Products Coatings. [R307-350]
II.B.2.c NEW The owner/operator shall comply with the applicable requirements of 40 CFR 63 Subpart N: National Emission Standards for Chromium Emissions from Hard and Decorative Chromium Electroplating and Chromium Anodizing Tanks. [40 CFR 63 Subpart N]

Engineer Review N121040008: Rocky Mountain Machine Shop Inc.- Salt Lake City Machine Shop December 2, 2024 Page 8
PERMIT HISTORY When issued, the approval order shall supersede (if a modification) or will be based on the following documents: Supersedes AO DAQE-AN0121040007-09 dated April 9, 2009
REVIEWER COMMENTS 1. Comment regarding 10-Year Review: This is an Administrative Amendment for a 10-Year Review to update the language, formatting, and layout of the Approval Order. The contact information was verified. The Requirements and Limitations were reorganized to match current DAQ permitting standards. The equipment list has been updated to include heaters that are listed for informational purposes through R307-401-10 Source Category Exemptions and R307-401-14 Used Oil Fuel Burned for Energy Recovery. When the source goes through its next modification, the emission estimates should be updated to include the heaters. [Last updated October 29, 2024] 2. Comment regarding Federal Rule Applicability: 40 CFR 63 Subpart N: National Emission Standards for Chromium Emissions from Hard and Decorative Chromium Electroplating and Chromium Anodizing Tanks 40 CFR Subpart N applies to each chromium electroplating or chromium anodizing tank at facilities performing hard chromium electroplating, decorative chromium electroplating, or chromium anodizing. Rocky Mountain Machine Shop Inc. has six (6) chrome plating tanks. This subpart applies to the source. In pervious permits, the source was required to perform testing for chrome at levels described in Subpart N. This requirement was removed from the previous permit because the results of the several previous stack tests indicate that it is unlikely that the chromium emissions exceed the standard in Subpart N. In addition, the MACT standard limit is below the detection limit of the prescribed method test. Therefore, the compliance demonstration becomes a mass balance exercise. The source is subject to a mass-balance limit to the amount of chrome solvent purchased per rolling 12-month period. The Director may require method testing of the chrome plating tanks at any time in the future. [Last updated August 7, 2024] 3. Comment regarding Title V Applicability: Title V of the 1990 Clean Air Act (Title V) applies to the following: 1. Any major source; 2. Any source subject to a standard, limitation, or other requirement under Section 111 of the Act, Standards of Performance for New Stationary Sources; 3. Any source subject to a standard or other requirement under Section 112 of the Act, Hazardous Air Pollutants; 4. Any Title IV affected source. This source is not a major source nor a Title IV affected source. The source is not subject to 40 CFR 60 (NSPS) nor 40 CFR 61 (NESHAP). The source is subject to 40 CFR 63 (MACT) Subpart N, which exempts a source from the requirements to obtain a Title V operating permit. There is no other

Engineer Review N121040008: Rocky Mountain Machine Shop Inc.- Salt Lake City Machine Shop December 2, 2024 Page 9
reason why the source should be required to obtain a Title V permit. Thus, Title V does not apply to the source. [Last updated October 29, 2024]

Engineer Review N121040008: Rocky Mountain Machine Shop Inc.- Salt Lake City Machine Shop December 2, 2024 Page 10
ACRONYMS The following lists commonly used acronyms and associated translations as they apply to this document: 40 CFR Title 40 of the Code of Federal Regulations AO Approval Order BACT Best Available Control Technology CAA Clean Air Act CAAA Clean Air Act Amendments CDS Classification Data System (used by EPA to classify sources by size/type) CEM Continuous emissions monitor CEMS Continuous emissions monitoring system CFR Code of Federal Regulations CMS Continuous monitoring system CO Carbon monoxide CO2 Carbon Dioxide CO2e Carbon Dioxide Equivalent - 40 CFR Part 98, Subpart A, Table A-1 COM Continuous opacity monitor DAQ/UDAQ Division of Air Quality DAQE This is a document tracking code for internal UDAQ use EPA Environmental Protection Agency FDCP Fugitive dust control plan GHG Greenhouse Gas(es) - 40 CFR 52.21 (b)(49)(i) GWP Global Warming Potential - 40 CFR Part 86.1818-12(a) HAP or HAPs Hazardous air pollutant(s) ITA Intent to Approve LB/HR Pounds per hour LB/YR Pounds per year MACT Maximum Achievable Control Technology MMBTU Million British Thermal Units NAA Nonattainment Area NAAQS National Ambient Air Quality Standards NESHAP National Emission Standards for Hazardous Air Pollutants NOI Notice of Intent NOx Oxides of nitrogen NSPS New Source Performance Standard NSR New Source Review PM10 Particulate matter less than 10 microns in size PM2.5 Particulate matter less than 2.5 microns in size PSD Prevention of Significant Deterioration PTE Potential to Emit R307 Rules Series 307 R307-401 Rules Series 307 - Section 401 SO2 Sulfur dioxide Title IV Title IV of the Clean Air Act Title V Title V of the Clean Air Act TPY Tons per year UAC Utah Administrative Code VOC Volatile organic compounds
Several emails were sent to the source, but the source routinely called me to answer the emails.

The first phone call was regarding updating source contact information, physical site address,
business mailing address, and billing address. I received a call back from Mike Busch on Aug
7th, 2024, and he confirmed that the addresses and source contact information listed in the
current permit and most recent compliance inspection are correct.

Following the peer review, I had a question for the source regarding the use of fuel combustion
equipment on site. When I called and spoke with the source, Mike Busch was unavailable, and
so I spoke with Bruce (801-554-0222) on October 18, 2024. I did not get his role at the
company. Based on my conversation with Bruce, the source burns left over hydraulic oil from
hydraulic cylinders that they repurpose/refurbish in heaters. They save the oil up over the year
and typically save only a few weeks worth to a month worth of oil to use in two building heaters
in the winter. The heaters are rated at 160,000 and 240,000 Btu/hr. In addition, the source has 4
natural gas fired heaters in one building and 3-4 natural gas fired heaters in another building. All
are rated at 250,000 Btu/hr.