DAQ-2025-002240

Rio Tinto Kennecott, 4700 Daybreak Parkway, South Jordan, Utah, 84009 4936-1399-6086.v3
April 15, 2025
Mr. Bryce Bird, Director
Department of Environmental Quality
Division of Air Quality
195 N 1950 W
Salt Lake City, UT 84116

Attention: Mr. Greg Mortensen, Ms. Erica Pryor, Ms. Becky Close:

Subject: Comments on the Utah Division of Air Quality’s
Amend R307-150. Emission Inventories.

Dear Mr. Bird,

Kennecott Utah Copper LLC (KUC) is submitting this letter to the Utah Division
of Air Quality (UDAQ) to provide comments on the proposed changes to the
Utah Administrative Code R307-150, Emissions Inventories. KUC understands
that UDAQ opened up R307-150 for revisions in order to make necessary
administrative changes to the rule related to the SO2 reporting language1.
However, UDAQ also proposed other revisions to R307-150 that have broader
implications that would have benefitted from pre-proposal engagement with
stakeholders that implement the rule. Given the lack of engagement, UDAQ
failed to correctly assess these broad implications and failed to consider the
added reporting burden that the revised rule would impose on regulated entities.
KUC has outlined these concerns in greater detail below and recommends the
following actions in the event that UDAQ proceeds by presenting a final rule to
the Utah Air Quality Board (AQB):
1. UDAQ should remove the proposed revisions that eliminate the
Hazardous Air Pollutants (HAPs) emissions thresholds; and
2. UDAQ should remove the proposed conditions that require all entities to
report mobile emission data as part of annual emissions inventories.
Given the broad implications of the rule, KUC also recommends that UDAQ
withdraw the proposed rule in its entirety, engage with stakeholders, and re-
propose another version of the rule. KUC’s environmental staff have extensive
experience implementing the current version of R307-150. In fact, preparing
emissions inventories to comply with the rule is one of the most labor-intensive
regulatory activities that KUC undertakes. With that in mind, KUC is more than
happy to have its environmental staff engage with UDAQ on the emissions

1 In reference to details on this rulemaking, KUC is relying on the information documented by UDAQ in the proposed
rule notice and information that was presented and discussed with UDAQ in a virtual meeting with Air and Waste
Management Association (AWMA) on March 13, 2025, hereafter referred to as “AWMA March 2025 meeting”.
Rio Tinto Kennecott
4700 Daybreak Parkway South Jordan, Utah
84009 Tel: [phone]
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inventory rule so that the rule drafters understand and appreciate the broad
implications that any proposed revisions would have on regulated entities.
Comment 1: Lack of Stakeholder Engagement
KUC is disappointed that this rule development was not discussed with industry
stakeholders prior to presenting to the AQB. In the past year, UDAQ has
proposed several rules with advanced rulemaking opportunities and
presentations at the UDAQ-hosted industry stakeholder meetings. KUC has
acknowledged the positive impact of the previous rulemaking engagement
activities in communications with UDAQ, yet UDAQ did not use any of these
forums for this rule.2
Opportunities such as round table discussions, advanced rulemaking actions,
and industry stakeholder meetings are valuable opportunities for KUC to
proactively manage upcoming compliance and reporting obligations and
engaging in such forums often results in effective and meaningful feedback.
For example, one of the things that UDAQ would have learned if it had engaged
with stakeholders prior to proposing revisions to R307-150 is that preparing
emissions inventories is a labor-intensive activity; for KUC’s operations, it takes
extensive effort from multiple staff to prepare KUC’s emissions inventories.
Given the necessary hours that KUC must dedicate to preparing emissions
inventories by April 15, KUC would have cautioned UDAQ that the timing of its
proposed rule didn’t make sense from a workload perspective because any
comments would be due contemporaneously with the comment period for the
rule. KUC finds UDAQ’s failure to recognize the overlap between emissions
inventory reporting and commenting on the rule extremely disappointing. KUC
truly believes that active engagement on this draft rule will result in meaningful
and effective feedback that will increase the effectiveness of such a proposal.
Comment 2: Justification for rule changes is not based on data
In section 3 of the Notice of Substantive Change summary, UDAQ presents
reasons for the changes to removing the Hazardous Air Pollutants (HAPs)
thresholds and adding mobile emissions.
For proposing to remove the HAPs thresholds from the rule, UDAQ outlines that
they cannot recreate the thresholds. As a replacement, they assert that having
no threshold is appropriate because:
SLEIS is now able to automatically populate any HAPs emission factors
with standard, well-defined methodology, therefore negating the need for
exemption limits.
This feature of SLEIS is not a justification for removing the thresholds. SLEIS is
a tool for submitting inventory data. The use of the tool does not guarantee
compliance and UDAQ is assuming user reliance on the tool. It is still the

2 KUC finds the omission of stakeholder engagement curious as it does not appear that the revisions to R307-150
were mandated by any particular deadline.
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responsibility of the users to ensure the data is representative. For example,
many KUC processes are interconnected and to ensure processes are
representative compared to each other, KUC prepares and reviews inventory
data outside of SLEIS. Then, KUC uses the template upload feature to populate
the data into SLEIS for submittal. It is unclear if UDAQ considered this feature in
their review.
For proposing to add mobile emissions reporting to the rule, UDAQ states:
This change will allow staff to level the playing field and mandate all
facilities to report these emissions.
The wording of this statement could be misinterpreted. KUC is concerned that it
lacks a level of acknowledgement for the work that is required for the regulated
community to comply with R307-150 requirements. UDAQ’s statement fails to
account for the true root cause of why UDAQ has some sources report mobile
emissions while others are exempt from reporting. Ultimately, UDAQ only
speculates that additional data could support the work of groups at the agency
but has not provided any clear data or examples of how these changes are an
improvement to the current methods. Additionally, UDAQ does not provide
details around how this data will be used and if this new reporting requirement
will lead to double counting of emissions specifically for sources that currently
report some mobile source emissions.
Comment 3: Rulemaking incorrectly assumes changes have no fiscal
impact
UDAQ has not completed the necessary outreach to properly confirm that the
fiscal impact of the rulemaking is indeed $0. KUC, and all reporting facilities,
spend extensive resources to collect the necessary data, verify the data, and
prepare the data for reporting. Engaging with the reporting community was
necessary research to understand of the potential fiscal impact of this proposed
rule. KUC recommends stakeholder engagement to ascertain the true fiscal
impact of this rule to the sources in the state.
Comment 4: UDAQ should clarify mobile emissions request outside of
rulemaking
KUC does not support the proposal to include mobile emissions reporting based
on the information summarized by UDAQ.
The proposed mobile emissions changes are so broad that there will be a
substantial amount of effort to understand the emissions associated with all
types of mobile equipment, regardless of size and extent of use, and their
operation. In the AWMA March 2025 meeting, UDAQ stated that the mobile
equipment covered by the rule included lawn mowers, snow blowers, as well as
typical industrial mobile equipment, such as haul trucks, construction and
excavation equipment, and industrial equipment like forklifts. This interpretation
is a very different – and much more broad interpretation – from KUC’s original
understanding of mobile emissions and will create additional levels of effort to
track operations for emissions reporting.
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For these reasons, UDAQ needs to invest more time and effort into clarifying the
justification for requesting mobile emissions to understand, what, if any, mobile
emissions are necessary for reporting. During the AWMA March 2025 meeting,
UDAQ stated that they would create a guidance document after the rule was
passed. KUC suggests that UDAQ should create the guidance document prior to
any potential rulemaking. The guidance should be created in partnership with
stakeholders to understand the level of effort and potential complications that
could impact the accuracy of the data which may not meet the proposed intent.
RECOMMENDATIONS
Ultimately, KUC believes the proposed revisions to R307-150 would greatly
benefit from proper stakeholder engagement. As such, KUC requests that UDAQ
withdraw the rule, engage with stakeholders, and then re-propose revisions in a
separate rule. Such an action is necessary because UDAQ should understand
how the changes to the emissions inventory rule affect the regulated community
prior to completing a rulemaking that has broad and onerous implementation
impacts. Additionally, KUC believes that publication of a guidance document
prior to this rulemaking allows for easier implementation and collection of
meaningful information.
In the event that UDAQ proceeds with the rule as currently proposed, UDAQ
must revise the proposal to (1) eliminate the provisions that remove the HAPs
emissions thresholds” and (2) remove the provisions that require “mobile source
emissions reporting.”.
Closing
KUC appreciates the opportunity to comment on the proposed changes to Utah
Administrative Code R307-150, Emissions Inventories. As always, KUC is
committed to working collaboratively with UDAQ on these issues and welcomes
additional discussions on the rule in the future.
Sincerely,

Jenny Esker Evans
Principal Advisor, Air Quality Permitting and Compliance