HomeMy WebLinkAboutDAQ-2025-002241
April 15, 2025
Mr. Greg Mortensen
Utah Division of Air Quality
P.O. Box 144820
Salt Lake City, Utah 84114-4820
Submitted by email to gmortensen@utah.gov
Subject: Utah Petroleum Association and Utah Mining Association Comments on Amend
R307-150. Emission Inventories.
Dear Mr. Mortensen:
For the February 2025 meeting of the Air Quality Board (“AQB”), the Utah Division of Air Quality
(“UDAQ”) provided proposed amendments to the emission inventory (“EI”) rule, R307-150.1 The
Utah Bulletin subsequently published the amendments for proposal.2 The Utah Petroleum
Association (“UPA”) and the Utah Mining Association (“UMA”) (collectively, the “Associations”)
appreciate the opportunity to submit these comments on the proposal Amend R307-150.
Emission Inventories (“Proposal”).
Additionally, we greatly appreciate the comments due date extension by 15 days to April 15, 2025.
UPA is a statewide oil and gas trade association established in 1958 representing companies
involved in all aspects of Utah’s oil and gas industry. UPA members range from independent
producers to midstream and service providers, to major oil and natural gas companies widely
recognized as industry leaders responsible for driving technology advancement resulting in
environmental and efficiency gains. Five member companies operate petroleum refineries in the
Northern Wasatch Front ozone nonattainment area and several other UPA member companies
operate oil and gas production and midstream facilities within the Uintah Basin ozone
nonattainment area. Our member companies include major source facilities that would be subject
to the rulemaking if implemented as proposed. Member vendors and suppliers also operate in
these areas. Our member companies have an interest in air quality, air emissions controls, and
related compliance requirements throughout Utah.
1 Agenda item number VII, Propose for Public Comment: Amend R307-150. Emission Inventories., Utah
Air Quality Board, February 5, 2025
2 Utah Bulletin, Volume 2025, Number 05, March 1, 2025, at 16.
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UMA was founded in 1915 and serves as the voice of Utah’s mine operators and service
companies which support the mining industry. The member companies operate hardrock,
industrial mineral, and coal mines throughout the State of Utah. UMA has an interest in air quality
in support of the communities in which our member companies operate and air emissions controls
and related compliance requirements in Utah.
The Proposal includes two major changes that affect our member companies. First, the Proposal
requires mobile emissions reporting. Secondly, the Proposal removes exemptions for reporting
Hazardous Air Pollutants (“HAPs”) below specified thresholds.
UDAQ presented the Proposal to the AQB with no advance notice to the regulated community.
As a result, the Associations and other potentially regulated entities had no prior opportunity to
provide input to the agency for consideration in shaping the amendments, the rule analysis, and
information provided to the Board. The rule analysis significantly underestimates the cost and
burden to implement the amendments. Furthermore, the agency indicated they expected benefits
to air quality photochemical modeling by reporting mobile emissions, but the Associations do not
anticipate an appreciable benefit. Regarding eliminating the reporting thresholds for HAPs,
UDAQ has not provided an adequate justification for selecting the zero reporting threshold.
Moreover, the information provided for the rulemaking record provides very little information on
the goals of the amendments.
We also identified some needed clerical or editorial changes, should UDAQ persist in completing
all or a portion of the rulemaking.
For these and other reasons and in summary, the Associations do not support the proposed
changes to R307-150 Emission Inventories. We recommend that UDAQ withdraw the
Proposal in its entirety. We explain our reasoning in greater detail below.
I. THE ASSOCIATIONS RECOMMEND THAT UDAQ WITHDRAW THE
PROPOSED AMENDMENTS TO REPORT MOBILE EMISSIONS.
The Proposal, if adopted as written, would require reporting mobile emissions for many facilities.
It defines “mobile emissions” as follows:
“Mobile Emissions” means emissions from mobile sources as defined in 40 CFR § 51.491
which never leave the property line.
The referenced federal regulation defines “mobile sources” as follows:
Mobile sources means on-road (highway) vehicles (e.g., automobiles, trucks and
motorcycles) and nonroad vehicles (e.g., trains, airplanes, agricultural equipment,
industrial equipment, construction vehicles, off-road motorcycles, and marine vessels).
Mobile emissions reporting would apply to:
• Major sources
• Part 70 sources
UPA and UMA Comments on Amend R307-150. Emission Inventories, April 15, 2025
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• Any source located in Davis, Salt Lake, Utah, or Weber Counties and that has the potential
to emit 25 tons or more per year of any combination of oxides of nitrogen, oxides of sulfur
and PM10, or the potential to emit ten tons or more per year of volatile organic compounds
For the reasons outlined in this portion of our comments, the Associations do not support
adding the mobile emissions reporting requirement and request that it be withdrawn.
A. The definition of “mobile emissions” and use of the emissions need
additional clarity, if UDAQ completes the amendments.
The Associations have concerns about clarity in the definition of “mobile emissions.” Multiple
questions discussed below need to be addressed in the definition and in the rulemaking record,
if UDAQ persists in moving forward with the rulemaking.
Based on the definitions, it appears that mobile emissions reporting would be required for the
following types of equipment if powered by fuel (i.e., gasoline, diesel, propane, butane, liquified
natural gas) and not by electricity or batteries and remain onsite for the full calendar year:
• Cars and trucks
• Side-by-sides and 4-wheelers
• Forklifts
• Cranes
• Riding lawn mowers (but not push or self-propelled mowers that are not riding mowers)
• Snowmobiles
• Locomotive rail switchers (unless they move outside the facility gate during operation)
• Scissor lifts and other types of man lifts
• Vacuum trucks
• Tractors
• Heavy mobile equipment such as bulldozers, backhoes, graders, etc.
• Any other onsite mobile equipment
The definition of “mobile emissions” includes the phrase “which never leave the property line.”
Never could be a very long time and, eventually, all equipment will leave when it is finally sold or
retired. Therefore, we recommend changing this phrase to “which do not leave the property
line during the calendar year for the emissions report.”
It is not clear whether the proposed requirement would apply to contractor owned and operated
equipment and to leased equipment. These need to be clarified. Leased vehicles may be easier
to track, but contractor vehicles will be much more difficult as they can easily move onsite or
offsite without necessarily being subject to facility owner/operator tracking. Both leased and
contractor vehicles enter the facility through different systems than purchased equipment and
their presence onsite may not be tracked at all. Tracking all non-owned vehicles will increase the
workload substantially. We recommend adding to the definition of “mobile” emissions “and
which are owned and operated by the facility owner or operator.”
We understand from discussion with UDAQ that the requirement would not apply to portable
equipment such as portable generators, portable light plants, and other equipment that does not
qualify as a vehicle capable of providing a means of travel or transport or of being driven on the
UPA and UMA Comments on Amend R307-150. Emission Inventories, April 15, 2025
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road.3 We recommend including the following helpful sentence in the mobile emissions
definition for clarity, “Mobile emissions do not include emissions from portable equipment
that cannot carry or convey passengers.” If not included in the definition, the statement must
at least be included in the response to comment or other part of the rulemaking record.
If we do not correctly understand the equipment that would be in or out of the reporting
requirement, then applicability needs to be further clarified in the rule, if UDAQ persists in moving
forward with the Proposal.
As discussed later in this letter, the complexities and workload required to gather the mobile
emissions information will be onerous. To reduce that workload, we recommend that UDAQ
include a minimum size for applicable equipment in the amendments. UDAQ could work
with facilities to identify an appropriate minimum size that could be omitted from mobile emissions
reporting.
Some facilities have concerns whether mobile emissions might be included in emission fees,
especially as interpretations of Utah rules may change over time with new staff and loss of
institutional memory. We understand that mobile emissions will not be billable emissions.4 We
did not find a definition of “billable emissions” within the UDAQ rules. However, we found an
explanation of vehicle emissions within the discussion of “chargeable emissions” in Utah’s Part
70 rule, as follows:
R307-415-9. Fees for Operating Permits.
Paragraph (3)(a)(iv) Emissions resulting directly from an internal combustion engine for
transportation purposes or from a non-road vehicle shall not be counted when calculating
chargeable emissions for a Part 70 source.
This paragraph provides adequate protection that no fee will be assessed or paid for mobile
emissions, but it may not be entirely clear for sources that do not have Part 70 applicability such
as those captured in R307-150(3)(c).5 We request that UDAQ include mention of this in the
response to comment or elsewhere in the rulemaking record for better documentation.
Similarly, some facilities have concerns that mobile emissions might count towards “major source”
status, either now or in the future with possible changing interpretations over time. The Proposal
refers the major source definition to R307-415-3 (Definitions for Operating Permit Requirements),
which includes the following language:
"Major source" means any stationary source (or any group of stationary sources that are
located on one or more contiguous or adjacent properties, and are under common control
of the same person (or persons under common control)) belonging to a single major
industrial grouping and that are described in paragraphs (a), (b), or (c) of this definition.
For the purposes of defining "major source," a stationary source or group of stationary
3 Teleconference with Air & Waste Management Association (“AWMA”), Utah Chapter, March 13, 2025
(“AWMA Meeting”).
4 AWMA Meeting.
5 R307-150(3)(c): source not included in Subsection[s] R307-150-3(2), R307-150-3(3)(a), or R307-150-
3(3)(b) that is located in Davis, Salt Lake, Utah, or Weber Counties and that has the potential to emit 25
tons or more per year of any combination of oxides of nitrogen, oxides of sulfur and PM10, or the potential
to emit [10]ten tons or more per year of volatile organic compounds;
UPA and UMA Comments on Amend R307-150. Emission Inventories, April 15, 2025
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sources shall be considered part of a single industrial grouping if all of the pollutant
emitting activities at such source or group of sources on contiguous or adjacent properties
belong to the same Major Group (all have the same two-digit code) as described in the
Standard Industrial Classification Manual, 1987. Emissions resulting directly from an
internal combustion engine for transportation purposes or from a non-road vehicle
shall not be considered in determining whether a stationary source is a major
source under this definition. [emphasis added]
Again, this paragraph provides adequate protection that no fee will be assessed or paid for mobile
emissions, but again may not be entirely clear for sources that do not have Part 70 applicability
such as those captured in R307-150(3)(c). We request that UDAQ include mention of this in
the response to comment or elsewhere in the rulemaking record for better documentation.
In summary, if UDAQ persists in moving forward with the rulemaking, we request that the
definition include more clarity to include only equipment owned and operated by the
facility owner/operator and does not include contractor, leased, or portable equipment.
We also request that UDAQ incorporate a minimum size threshold for reporting, to reduce
the workload. We further request that the response to comment include clarification and
mention rule language from R307-415 demonstrating that mobile emissions will not be
included in emission fees or in the basis for determining major source status.
B. Mobile emissions reporting will not be practicable for regulated
facilities to implement and the requirement should be withdrawn.
UDAQ stated that:
Staff do not anticipate a large workload increase for reporting these emissions as many
sources already track fuel use and operational hours of equipment. Workload would be
further limited as emissions reporting would be restricted to equipment that does not leave
the facility’s property in a given year.6
UDAQ staff greatly underestimated the work that will be involved. The calculations will be far
more complex and will require extensive hours to set up systems, train personnel, track, account
for, and evaluate emissions for facilities, especially for the larger complex facilities owned and
operated by member companies of the Associations. As a result of the extensive work required
and minimal benefits obtained (described in sections below), mobile emissions reporting will not
be practicable for regulated facilities to implement.
The accuracy of mobile emission calculations rely on identifying key engine specifications such
as manufacturer, horsepower, emission standards, emission factors, etc. If a facility does not
incorporate these details for each mobile emission source onsite, the emissions estimate
accuracy will be poor.
For example, for a site operating 25 pieces of applicable equipment including only forklifts,
manlifts, and cranes, the equipment may be of 25 different ages, models, and/or manufacturers.
Equipment of each type may be fueled by any of gasoline, diesel, propane, or battery power.
Some equipment may not have hour meters, but even if it does, assigning fuel use by hours to
such a variety of equipment will increase inaccuracy. The facility may not be tracking the actual
6 Board Memo at 2.
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fuel use for each piece of equipment and, since the fuel supply will be divvied among so many
types of equipment, it will be impossible to have an accurate accounting of fuel used by each
device without implementing a detailed fuel use tracking system that could be subject to
quantification errors, input errors, and misses.
Equipment may be bought and sold or retired throughout the year, resulting in the need to track
relevant dates and, for equipment that didn’t stay onsite for the full calendar year, remove it from
the annual calculation. Moreover, equipment sent offsite for repairs would need to have relevant
dates tracked and be removed from the annual calculation. And if the rule applies to leased
equipment, any leased equipment that would be swapped out during the course of the year would
also need to have relevant dates tracked and be removed from calculations, even if swapped for
an identical model of equipment. For equipment that does not remain onsite, the facility will have
a burden of proof to document and show this.
Required information may not be readily available from the vendors who supply the equipment,
particularly for smaller engines or older ones. Without this information, the EI does not gain
accuracy. Some equipment does not have an hour meter and the only way to track emissions
will be through the amount of fuel used, which will require a log and, depending on the method of
fueling, may not be a reliable way to gather data. Due to equipment variations, the calculation will
not be as simple as divvying the fuel used by numbers of equipment and hours operated.
And then, once the information has been gathered, the task of sorting through it and producing
calculations for each piece of equipment will consume significant time.
All of this poses an enormous amount of work to account for each piece of applicable equipment
and track it. Those facilities subject to the certification requirement of existing R3-7-150-9 bear a
greater burden of ensuring accuracy and cannot ignore any details.7
Of the 55% of point sources that reported mobile emissions,8 we do not know the extent to which
the facilities gathered detailed information. And if they gathered it, we do not know how many of
the sources were small or not complex, and therefore the information may have been relatively
easy to gather.
Furthermore, the complexities described above will multiply exponentially for a large, complex site
such as those owned and operated by our member companies, who have a significant quantity
and variety of applicable equipment. For example, in addition to forklifts, manlifts, and cranes
discussed above, our member companies have vacuum trucks, rail switcher engines, backhoes,
tractors, 4-wheelers and side-by-sides, riding lawn mowers, snowmobiles, and other heavy
equipment.
We understand that UDAQ hopes that facilities can implement the requirements in a piecemeal
fashion and, over a period of two to three years, have a good system.9 But the Proposal does not
7 R307-150-3 Applicability, paragraph (5) reads as follows: “Section R307-150-9 applies to stationary
sources located in a designated ozone nonattainment area that have the potential to emit oxides of
nitrogen or volatile organic compounds greater than 25 tons per year.” R307-150-9 includes a
requirement to submit an annual ozone emissions statement and, “a certification that the information
contained in the statement is accurate to the best knowledge of the individual certifying the statement.”
8 Board Memo at 2: “As emissions inventories were passed on to technical analysis staff for modeling, it
was noted that the majority of point sources (230 of 421 sources) reported mobile emissions, but other
facilities did not.” 230/421 = 55%.
9 AWMA Meeting.
UPA and UMA Comments on Amend R307-150. Emission Inventories, April 15, 2025
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allow for this. Our member companies cannot rely on enforcement discretion to allow
noncompliance or partial compliance. Moreover, companies would not be able to provide the
required certification if they planned to rely on enforcement discretion.
In conclusion, the numerous complexities of gathering mobile emissions data and being
able to certify it to the accuracy level required renders the requirement impracticable.
Therefore, the rulemaking for mobile emissions should be withdrawn.
C. The cost to implement mobile emissions reporting will be much higher
than estimated, providing additional justification to withdraw the Proposal.
The fiscal information section of the rule analysis indicates:
If not already reporting, there is a possible workload increase to track mobile source use
on a facility. However, there are no or negligible costs anticipated for HAPs reporting due
to automated processes for non-small businesses associated with the amendments to
Rule R307-150. . . . workloads costs should be significantly reduced as SLEIS provides
the means to input activity data (e.g. fuel use or operating hours, both of which are typically
tracked by sources as part of their normal business practices) to calculate emissions.
Thus, once the source adds the equipment types and number thereof to SLEIS, they only
need to input activity data going forward as SLEIS will carry their equipment type and
number from year-to-year.
Furthermore, the regulatory impact summary table indicated zero costs to non-small businesses
during FY2025, FY2026, and FY2027.
As discussed above regarding the workload to implement mobile emissions reporting, the work
will require weeks of staff time per year to gather data and calculate emissions.
Prior to implementing reporting, companies will need to establish systems to gather information
and calculate emissions and training for all applicable personnel who may operate, fuel, maintain,
purchase, or lease applicable equipment. Developing and maintaining systems and training will
require additional staff time over and above that discussed above including (but not limited to)
costs to develop or modify computer software systems, resulting in a large development cost up
front, prior to gathering any data. Facilities will incur ongoing costs to maintain systems, computer
software, and training.
Reporting mobile emissions will bear significant costs to implement all of the required
tasks. While we recommend withdrawing the rulemaking, if UDAQ continues with it, these
costs must be estimated and considered.
D. Mobile emissions reporting will not improve relative overall accuracy
and therefore should not be required.
We understand that UDAQ currently accounts for all mobile emissions through its area-wide
mobile source emissions estimations. If facilities must report their mobile emissions through
SLEIS, then the count of mobile emissions equipment in UDAQ’s emission calculations will need
to be reduced accordingly. We expect a small reduction, relatively speaking. More importantly,
calculating the emissions through SLEIS will not improve accuracy of emission estimates.
UPA and UMA Comments on Amend R307-150. Emission Inventories, April 15, 2025
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SLEIS bases its calculations on AP-42 emission factors or similar information but these factors
are known to be inherently inaccurate. The factors are not likely to be accurate predictors of
emissions from any one specific source, except in very limited scenarios. Even emission factors
with more highly rated AP-42 grades of “A” or “B” are only based on averages of data from multiple
similar sources. EPA reports that half of the emission factors are rated “D” or “E,” one-fifth are
unrated, and less than one-third of the emission factors are rated between “Excellent” and
“Average.” EPA also reports the following:
The extent of between-source variability that exists, even among similar individual
sources, can be large depending on process, control system, and pollutant. Although the
causes of this variability are considered in emission factor development, this type of
information is seldom included in emission test reports used to develop AP-42 factors. As
a result, some emission factors are derived from tests that may vary by an order of
magnitude or more. Even when the major process variables are accounted for, the
emission factors developed may be the result of averaging source tests that differ by
factors of five or more.10
Moreover, EPA rated all of the applicable AP-42 emission factors except for CO2 for uncontrolled
gasoline and diesel industrial engines as “D” or “F.”11 These factors were developed in 1995 with
minimal and nonsubstantive updates since then12 and therefore do not incorporate any reductions
in emissions from newer equipment in the past thirty years.
Furthermore, returning to our forklift example, two recent peer reviewed journal articles describe
wide variation in forklift emissions:
• Pang, Zhang, and Ma report that most of the emissions factors estimated from their study
differ significantly from those in well-developed emission factor models such as
NONROAD by EPA. They suggest that localized, preferably fuel-based emission factors
should be adjusted based on real-world emission measurements in order to develop a
representative emission inventory for non-road equipment. They further report, “there
exists a large inter-and intra-forklifts variability in emissions. The inter-forklift variability in
emissions is mainly due to engine make, model, age, compliance emissions standards,
and others. The intra-forklift variability in emissions is mainly due to duty-cycle changes.
Comparing time-based emissions with fuel-based emissions, the latter exhibit less
variability.”13
• Ziółkowski, Fuć, and Jagielski report differences in NOx emissions for forklifts depending
on whether they are operated inside or outside of a warehouse (possibly due to different
10 For this information and a discussion of the variability and inaccuracies of AP-42 factors, see EPA
Enforcement Alert, EPA Reminder About Inappropriate Use of AP-42 Emission Factors, Publication
Number EPA 325-N-20-001, November 2020, located at https://www.epa.gov/sites/default/files/2021-
01/documents/ap42-enforcementalert.pdf (accessed on April 12, 2025).
11 See AP-42, Fifth Edition, Volume I, Chapter 3: Stationary Internal Combustion Sources, Section 3.3
Diesel and Gasoline Industrial Engines, Table 3.3-1 Emission Factors for Uncontrolled Gasoline and
Diesel Industrial Engines at 3.3-7 (“AP-42 for Industrial Engines”) located at
https://www.epa.gov/system/files/documents/2025-04/c03s03_april2025.pdf (accessed on April 13, 2025).
12 AP-42 for Industrial Engines at 3.3-6.
13 Kaili Pang, Kaishan Zhang, Shuai Ma, Tailpipe emission characterizations of diesel-fueled forklifts
under real-world operations using a portable emission measurement system, Journal of Environmental
Sciences, Volume 100, 2021, Pages 34-42, available at
https://www.sciencedirect.com/science/article/pii/S1001074220303144 (accessed on April 13, 2025).
UPA and UMA Comments on Amend R307-150. Emission Inventories, April 15, 2025
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driving methods such as speed, braking, etc.). They also reported NOx, CO, and
hydrocarbon emission differences and fuel consumption differences of up to a factor of
two for carrying a load or not carrying a load. These differences held true for a
compression ignition engine fueled by diesel and for a spark ignition engine fueled by
liquified petroleum gas (“LPG”).14
It would be entirely impracticable to attempt to address such variations in the mobile emissions
calculations but nonetheless, these articles illustrate some of the inaccuracies in forklift emissions
calculations. While we focused our research only on forklift emissions, we would anticipate similar
types of variation for other applicable equipment.
Mobile emissions calculations can be expected to have a lower accuracy level than stationary
source emissions already reported by facilities, where emissions, emission indicators, or
surrogates are often measured through various means such as stack tests, Continuous Emissions
Monitoring Systems, parametric systems, and Leak Detection and Repair programs.
UDAQ indicated they would like to use the mobile emissions calculations to support policy
decisions.15 Considering all of the inherent variation, we would not support using these
calculations for policy decisions especially if they separate reporting facilities and apply different
policies than for non-reporting operations.
In conclusion, the variation in actual emissions from calculated emissions may be great,
and does not justify the work entailed to calculate the emissions, reinforcing our
recommendation to withdraw the rulemaking.
E. Mobile emissions reporting will not enhance photochemical modeling
inputs sufficiently for the work required, and therefore does not justify
finalizing the mobile emissions requirement.
UDAQ stated, “Technical analysis and policy staff noted that having a consistent and
comprehensive emissions inventory on point sources would allow for more accurate emissions
spatial allocation, reduced uncertainty, enhanced model performance, and more accurate policy
evaluation, if/when needed.”
We have already shown that accuracy will not improve and uncertainty will not reduce, nor will
policy evaluation improve by requiring applicable facilities to report mobile emissions.
We asked Ramboll to comment on providing mobile emissions as a means to improve spatial
allocation and enhance model performance. They provided us with the attached memo to
comment on these claims.16 In summary, Ramboll said the following:
14 ZIÓŁKOWSKI, A., FUĆ, P., JAGIELSKI, A. et al. Analysis of emissions and fuel forklifts by location of
operation. Combustion Engines. 2022, 189(2), 30-35, located at
https://www.researchgate.net/publication/354706590_Analysis_of_emissions_and_fuel_consumption_fro
m_forklifts_by_location_of_operation (accessed on April 13, 2025).
15 Memorandum, PROPOSE FOR PUBLIC COMMENT: Amend R307-150. Emission Inventories. Greg
Mortensen, Inventory Section Manager through Erica Pryor, Rules Coordinator and through Bryce C.
Bird, Executive Secretary to Air Quality Board, January 23, 2025 (“Board Memo” or “Memo”) at 2.
16 Proposal to Inventory Mobile Source Emissions at Major Source Facilities: Impacts on Regulatory
Photochemical Modeling, Ramboll Environment and Health.
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• Emission calculations of applicable vehicles in EPA’s MOVES model, where the emission
calculations currently occur, would be more accurate than those done in SLEIS using AP-
42 or similar factors and AP-42 will likely overstate emissions.
• The impact on modeling inventories and air quality predictions would remain well within
current modeling uncertainty.
• Placing the anticipated small amount of incremental mobile source emissions at facility
coordinates would not make a difference relative to the entire nonattainment area.
• The change to the mobile source inventory would not provide equivalent benefits for the
amount of work involved.
Thus, improvements in spatial allocation and photochemical modeling will be of marginal value at
best.
Ramboll’s conclusion that the photochemical modeling benefits obtained will not be worth
the amount of work required reinforces our conclusion that the mobile emissions reporting
proposal should be withdrawn.
F. UDAQ did not justify mobile emissions reporting sufficiently to meet
the requirements of Utah Code 19-2-106.
UDAQ indicated the authority for this rulemaking falls under Utah Code 19-2-106.17
In justification for adding this reporting element, UDAQ stated the following in the Board Memo:18
As emissions inventories were passed on to technical analysis staff for modeling, it was
noted that the majority of point sources (230 of 421 sources) reported mobile emissions,
but other facilities did not. Inventory staff noted that the inconsistency was due to a
combination of some sources having a specific reporting requirement in their permits and
many others voluntarily reported these emissions as there was no explicit requirement in
rule R307-150.
A meeting with various DAQ sections (including technical analysis, policy, emissions
inventory, and compliance) was subsequently held to discuss the issue. Technical
analysis and policy staff noted that having a consistent and comprehensive emissions
inventory on point sources would allow for more accurate emissions spatial allocation,
reduced uncertainty, enhanced model performance, and more accurate policy evaluation,
if/when needed. Emissions inventory staff noted that most sources are already submitting
these emissions and SLEIS is capable of automatically calculating the emissions based
on fuel use or operation hours once a source populates the mobile process in SLEIS. Staff
do not anticipate a large workload increase for reporting these emissions as many sources
already track fuel use and operational hours of equipment. Workload would be further
limited as emissions reporting would be restricted to equipment that does not leave the
facility’s property in a given year.
In the rule analysis accompanying the Board Memo, UDAQ justified mobile emissions reporting
by stating, “This change will allow staff to level the playing field and mandate all facilities to report
17 Email, Greg Mortensen to Marise Textor, March 10, 2025, indicating that the statutory authority listed in
the rule analysis, Section 19-6a-1642, is incorrect, and the correct authority is 19-2-106.
18 Board Memo at 2.
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these emissions. This will result in a more comprehensive point source inventory which can be
leveraged for modeling and policy purposes.”
Utah Code 19-2-106 addressing rulemaking authority and procedure requires that the board “may
make rules for the purpose of administering a program under the federal Clean Air Act different
than the corresponding federal regulations which address the same circumstances if the board
holds a public comment period . . . and a public hearing; and the board finds that the different rule
will provide reasonable added protections to public health or the environment of the state or a
particular regions of the state”. These findings must be in writing and must be based on evidence,
studies, or other information contained in the record that relates to the state of Utah and the type
of source involved.19
We have shown above that the benefits of the proposed mobile emissions reporting will be
marginal at best, and will not provide any real benefit for the photochemical modeling or for policy
decisions. We have also shown that a tremendous amount of work will be required to report
mobile emissions. The only data provided by UDAQ to justify mobile emissions reporting is that
55% of facilities reported it, but did not provide any data for the level of detail used in the
calculations from those facilities. “Leveling the playing field” does not justify this rulemaking. We
see no evidence, studies, or other information in the record demonstrating that the requirement
will provide reasonable added protections to public health or the environment of the state or
particular regions of the state. And the information that we gathered and presented above is
contrary to these requirements of 19-2-106.
Thus, we conclude that the rulemaking has not been adequately justified to meet the bar of
Utah Code 19-2-106 and therefore must be withdrawn.
G. The rule should not be effective any earlier than the emissions
reported in 2027 (and possibly 2028) for emissions incurred in 2026 (or
possibly 2027), if UDAQ persists in finalizing the Proposal.
UDAQ indicated that they expected the rulemaking to be effective for EI reports submitted in 2026
based on data gathered in 2025.20
Meeting this timetable will be impossible. Facilities need time to gather the required data about
numbers and types of applicable equipment, develop systems for gathering the information, and
train applicable field personnel. This work will require at least six months from the date of adopting
a final rule. No data can be gathered until this preparatory work has been completed. Therefore,
the earliest that companies can gather data will be 2026 and the earliest that they can report on
mobile emissions will be 2027. If the rulemaking is not finalized by the end of second quarter this
year and guidance developed shortly thereafter, the timing for implementation will need to be
increased by another year.
We recommend if UDAQ proceeds with the rulemaking, that words be added to the rule
indicating that mobile emissions reporting will be required starting in 2027 or 2028 for 2026
or 2027 emissions, respectively, based on the date the rule gets finalized. We propose the
following wording for R307-150-5(1) and R307-150-6(1):
19 Utah Code 19-2-106, Rulemaking authority and procedures, paragraphs (1)(a) and (2)(a) and (b).
20 AWMA Meeting.
UPA and UMA Comments on Amend R307-150. Emission Inventories, April 15, 2025
Page 12 of 15
R307-150-5(1) Each large major source shall submit an emission inventory annually
beginning with calendar year 2002. The inventory shall include PM10, PM2.5, oxides of
sulfur, oxides of nitrogen, carbon monoxide, volatile organic compounds, and ammonia
for emissions units including fugitive emissions and, starting with 2026 emissions reported
in 2027, mobile emissions.
R307-150-6(1) Each source identified in Subsection R307-150-3(3) shall submit an
inventory every third year beginning with calendar year 2002 for emissions units including
fugitive emissions and, starting with 2026 emissions reported in 2027, mobile emissions.
As noted above, if the rule has not been adopted by the end of second quarter 2025 with guidance
issued shortly thereafter, we ask that the dates be delayed by another year, to allow adequate
preparation and implementation time as discussed above.
II. UDAQ SHOULD NOT ELIMINATE HAP REPORTING
THRESHOLDS.
The Proposal, if finalized as written, would eliminate reporting thresholds for HAPs. The
Associations do not support eliminating these thresholds.
UDAQ indicated they were unable to find a basis for the specific HAP reporting thresholds in
R307-150 in the Board Memo for the rulemaking and wrote the following:
Emissions inventory staff began to seek alternative means to calculate HAPs reporting
exemptions and working with the State and Local Emissions Inventory System (SLEIS)
vendor to evaluate the ability of the program to automatically calculate HAPs based on
already required material throughputs and established emission factors. The SLEIS
vendor subsequently provided a program enhancement which automatically populates
HAPs. The enhancement was applied during the 2023-point source emissions inventory
collection and proved successful.21, 22
The Board Memo goes on to say, “More importantly, this proposed change allows sources and
DAQ to leverage SLEIS’s capability and will align the rule with what sources are already reporting
in SLEIS.”23
Including HAP reporting in SLEIS to leverage its capability is entirely different than eliminating the
HAP reporting thresholds in R307-150. The Associations do not object to including HAP reporting
through SLEIS, which is not an aspect of this proposed rulemaking. But eliminating the minimum
thresholds poses concerns for members of the Associations. Our comments on HAP reporting
focus on eliminating the thresholds.
The Board Memo indicates that a reporting threshold would not likely reduce the workload for a
source because regulated facilities must still estimate HAP emissions to determine whether they
exceed the reporting threshold. The Memo also says, “Furthermore, having an expected HAPs
21 Board Memo at 1.
22 Neither the Board Memo nor anything else in the record defines any criteria for “successful” or
describes any means to assess a successful implementation.
23 Board Memo at 2.
UPA and UMA Comments on Amend R307-150. Emission Inventories, April 15, 2025
Page 13 of 15
list auto-populate in SLEIS reduces the uncertainty for which HAPs sources may need to report
for a given process and should save manual calculation time.”24
However, in our estimation, eliminating the threshold will increase the workload and does not
reduce uncertainty. Sources can now use process knowledge to determine if reporting may be
required, especially if they have information that the process does not contain or does not emit a
particular HAP. In the absence of reporting thresholds, sources must certify that the emissions
of many HAPs are zero, a difficult certification to make because, even with process knowledge
that a certain HAP may not be expected to be emitted, it may be emitted in a trace or very small
quantity. Thus, we do not agree with the following statement from the fiscal information section
of the rule analysis, “there is a strong potential that this will reduce workload for sources as they
are already expected to determine if their HAP emissions are above or below the threshold in the
current rule which involves a complex calculation for each pollutant.” Incorporating the
calculations into SLEIS will reduce the workload but is not part of the rulemaking. Eliminating
the thresholds, which is part of the rulemaking, will likely increase the workload for many
facilities, especially those subject to the certification requirement of existing R307-150-9.
SLEIS bases its calculations on AP-42 emission factors or similar information (unless the
reporting facility adds additional detail of emissions for its specific equipment) and as discussed
earlier in this letter, AP-42 factors are known to have inherent inaccuracies.
Thus, relying on SLEIS calculations to show that an emission of a HAP is zero countermands the
required certification in existing R307-150-9. It is not clear if facilities would need to do sampling
to measure concentrations of HAPs that are expected to be low. If yes, then protocols would
need to be specified in the rulemaking for sampling in every type of situation and for analyses,
and the amount of work and associated costs would increase inordinately.
Furthermore, although the existing reporting thresholds in R307-150 seem to be arbitrary because
UDAQ cannot replicate them or find their original bases, eliminating the thresholds entirely is
equally arbitrary. Why not move the threshold to ten pounds per year like Louisianna and
Wyoming use? Why not choose 200 pounds per year like South Carolina uses?25 With the
information currently in hand, any change to the reporting thresholds is arbitrary. Although UDAQ
cannot locate or replicate the basis for current thresholds, the thresholds are sufficiently detailed
that UDAQ probably had a basis at the time of adopting them.
The Associations recommend that UDAQ not eliminate or change the HAP reporting
thresholds at this time. Choosing zero or any other value for the thresholds -- with the
information or lack thereof that UDAQ reported having in the Board Memo -- provides no better
basis than the current thresholds seem to have. Trying to fix something that is unsubstantiated
by replacing it with something else unsubstantiated does not make a good fix and does not meet
the bar of Utah Code 19-2-106. Furthermore, uncertainties in emission factors will make the
important aspect of certifying any emission estimate of zero an untenable task.
24 Board Memo at 2.
25 See Board Memo at 1 for reporting thresholds in other states.
UPA and UMA Comments on Amend R307-150. Emission Inventories, April 15, 2025
Page 14 of 15
III. IF UDAQ PROCEEDS WITH SOME OR ALL OF THE RULEMAKING,
THE ASSOCIATIONS RECOMMEND CLERICAL AND EDITORIAL
CHANGES.
We identified the following clerical and editorial changes needed to the Proposal, if UDAQ decides
to proceed with the rulemaking:
• UDAQ indicated that a major source or Part 70 source of emissions with Standard
Industrial Classification codes in the major group 13 would be subject to major source and
Part 70 source reporting under R307-150-6 and also to oil and gas industry reporting
under existing R307-150-8.26 R307-150-3(1)(c) indicates that large stationary sources of
sulfur dioxide, i.e. those with 100 tons per year or more of sulfur dioxide emissions, “may
be subject to other sections of Rule R307-150-3.” For clarity, we recommend that a similar
statement be added in the appropriate location to indicate the same for major sources and
Part 70 sources with Standard Industrial Classification codes in the major group 13.
• Due to eliminating R307-150-7 Exempted Hazardous Air Pollutants, the Proposal
renumbers subsequent sections. Therefore, references to subsequent sections need to
be renumbered accordingly. We recommend renumbering the references to Section
“R307-150-8” to “R307-105-7.” The incorrect references appear in R307-150(4) and
R307-150(4)(a). Similarly, the reference to “R307-150-9” in R307-150-3(5) should be
updated to “R307-150-8.”
• The rule analysis indicates the statutory authority for the rule to be “Section 19-6a-1642”
which needs to be corrected.
IV. SUMMARY
In conclusion, the Associations recommend that UDAQ withdraw the rulemaking in its entirety.
The amount of work and the costs associated with the increased reporting does not justify the
added requirements due to negligible benefits. Moreover, the rulemaking has not been properly
justified to meet the requirements of the Utah Code for rules that exceed federal requirements.
If UDAQ persists in finalizing the Proposal, a number of clarifications need to be added to the rule
or included in the record as discussed above, and a minimum size threshold for reporting mobile
emissions should be included. Furthermore, UDAQ mentioned that they would develop guidance
for the new requirements.27 This guidance would need to be available well before the start of the
first year of data gathering. Otherwise, companies will spend time developing internal data
gathering systems and training for applicable personnel that may be incorrect, or may not have
adequate preparation time for data gathering with the start of the year.
26 Email, Greg Mortensen to Marise Textor, March 5, 2025.
27 AWMA Meeting.
UPA and UMA Comments on Amend R307-150. Emission Inventories, April 15, 2025
Page 15 of 15
Once again, we appreciate the opportunity to provide comments on the Proposal.
Sincerely,
Rikki Hrenko-Browning Brian Somers
President, Utah Petroleum Association President, Utah Mining Association
cc: Bryce Bird - bbird@utah.gov
Becky Close – bclose@utah.gov
Ryan Bares - rbares@utah.gov
Rachel Chamberlain - rachelchamberlain@utah.gov
Chris Pennell - cpennell@utah.gov
Catherine Williams - catherinewilliams@utah.gov
Attachment: Proposal to Inventory Mobile Source Emissions at Major Source Facilities: Impacts
on Regulatory Photochemical Modeling, Ramboll Environment and Health.
1/1
Proposal to Inventory Mobile Source Emissions at Major Source Facilities: Impacts on
Regulatory Photochemical Modeling
We understand that the Utah Division of Air Quality (UDAQ) is proposing to require major stationary
sources1 within the Northern Wasatch Front to develop and submit an inventory of mobile source
emissions operating within their facilities to the State and Local Emission Inventory System (SLEIS) for
permitted point sources. The term “mobile sources” include both on-road vehicles (cars and trucks) and
nonroad vehicles and equipment (haulers, front loaders, cranes, forklifts, etc.) that remain onsite for
the year. Besides California’s various nonroad diesel equipment reporting requirements (e.g., In-Use
Off-Road Diesel-Fueled Fleets Regulation), we are not aware of other states with regulatory programs
tied specifically to requiring industries to inventory and report their vehicle and equipment fleet
emissions that operate within their facility fence lines. This statement opines on the proposal’s likely
negligible to minimal impact on UDAQ’s photochemical modeling performed in support of the State
Implementation Plan. We expect that the proposal would not improve or benefit modeling results in a
measurable way for the effort required to develop the facility-specific mobile inventories.
First, we understand that UDAQ is proposing that emission inventories would be based on detailed
accounting of fleet vehicles/types, activity (via fuel usage), and standard emission factors (e.g., AP-42).
Emission factors published in AP-42 are typically dated and not representative of more modern
equipment controls, operating modes, etc. In contrast, emission factors derived by the EPA’s MOVES
model are based on extensive modern engine testing and represent significant improvements over AP-
42. There may be some overlap in emission factors between AP-42 and MOVES for pre-2000 model
years, but not likely for equipment certified to recent standards. Therefore, AP-42 may yield highly
uncertain and likely overstated emissions for the reported facility fleets.
Second, the impact on modeling inventories and air quality predictions would remain well within current
modeling uncertainty. Placing the anticipated small amount of incremental mobile source emissions at
facility coordinates would not make a difference relative to the entire nonattainment area. Urban-wide
sector-specific emission inventories are considered sufficiently representative when their uncertainty is
within 20-30%. Photochemical model results are considered to be adequate when they yield ozone
biases and gross (unsigned) errors within 10-15% and 20%, respectively, and PM biases/errors within
20-30%. As one of the most extreme examples, biogenic emissions from different models and versions
often differ by orders of magnitude. Area source emission inventories (residential and commercial –
restaurants, dry cleaners, gas stations, etc.) are historically estimated from surrogate information such
as population, housing units, economic data, and continuously projected year after year. This results in
carrying along, and likely magnifying, uncertainties inherited from the original historical estimates. For
example, the importance of volatile consumer products (VCP – paints, adhesives, solvents, personal
care) has recently garnered new attention as recent improvements in data and methodology have
resulted in massive adjustments to this area source sector, again by orders of magnitude in some cases.
In conclusion, the fine tuning associated with adding incremental facility vehicle emission estimates in a
few relevant specific grid cells would represent a very small change to the overall modeling emissions
inventory compared to the total error inherent in the modeling. The change to the mobile source
inventory would not provide equivalent benefits for the amount of work involved.
1 The term “major stationary sources” is defined by the current nonattainment classification for the 2015 Ozone National Ambient Air Quality Standard.