DAQ-2025-003658

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P.O. Box 527,Emery, Utah 84522
Phone: [phone] - Fax: [phone]
Dt]PAtI]MENT OF
ENVIHONMLNIAL QUALITY
.ttJN 2 j 2c25
DIVISION OF AIR OUALITY
ta:
June 16,2025
Mr. Rik Ombach
Compliance Section
Utah Department of Environmental Quality
Division of Air Quality
195 North 1950 West, P.O. Box 144823
Salt Lake City, Utah 84114-4820
Re: Opocity Moniloring oi the Emery Mine
Dear Mr. Ombach:
td7Jl_L
This letter presents the results of visible emissions observations performed at the Bronco Utah Operations,
LLC Emery Deep Mine (Emery Mine) located in Emery County, Utah. The mine is operated by Bronco Utah
Operations, LLC (Bronco), who contracted with Barr Engineering Co. (Barr) to perform the observations in
compliance with the minor source Approval Order DAQE-AN0229006-05 (AO) issued by the Utah Division
of Air Quality (UDAQ). Taylon Earl of Barr, an EPA Method 9 Certified Visible Emissions Reader (see
Attachment 3), conducted opacity readings at the Emery mine on May 30, 2025.
The Clean AirActamendments of 1970 directed the Environmental Protection Agencyto develop New
Source Performance Standards (NSPS) for new and modified stationary sources of air pollutants. These
Standards of Performance for New Stationary Sources (40 CFR Part 60) have been adopted by the UDAQ,
and all AOs issued by the agency include emissions limitations as well as requirements for monitoring,
testing, reporting, and recordkeeping for applicable standards.
Emery Mine Emissions Testing Stondords ond Procedures
The Emery Mine is subject to Section 60.255(bX2) of Subpart Y of the NSPS which applies to facilities that
commenced construction, reconstruction, or modification after April 28, 2008. Thls Section requires that
performance tests be conducted periodically during normal operation of the mine to demonstrate
compliance with the applicable emissions standard stated in the AO, with the frequency of the
performance tests dependent on the results of the most recent performance test. The AO for the Emery
Mine was modified to include additional equipment and was approved on December 19,2016. This AO
expanded operations of the Emery Mine to include a new mine portal for underground mining and new
lune 16, 2025
Paqe 2
coal processing equipment. Barr performed a performance test and these results are compared to opacity
limits from mine specific emission points perthe approved AO and are included in Table 1.
Method 9 visible emissions observations were performed according to the test methods and procedures
outlined in the NSPS Subpart Y, Section 60.257(a)(1)-(3) and the approved AO. For sources subject to the
NSPS, these procedures require one-hour observations of each source (ten 6-minute averages) in the
initial performance test. However, in subsequent tests, if all of the 6-minute averages are equal to or less
than half the applicable opacity limit, then the observation time may be reduced to 30 minutes. As stated
in Section ll.B.2.b of the AO, visible emissions observations for mobile equipment in operational areas use
procedures similarto Method 9 but the requirement for observations at 15 second intervals over a 6-
minute period does not apply. For the haul road, opacity was observed at 6-points along the road from a
fixed observation point as trucks drove by. For truck loadout, which was intermittent, observations were
made for two 6-minute periods over a twenty-minute time frame using standard Method 9 procedures. A
tabulation of either the 6-minute or 6-point average visible emissions for each observed source is
included in Attachment 1 to this letter and the opacity observation field sheets are included in Attachment
2. The observer's Method 9 certificate ls included as Attachment 3. The sources observed and the
locations where each of the observations were conducted are depicted on Figure 1.
Emery Mine Emissions Observotion Results
The mine facilities include four conveyors that deliver run-of mine (ROM) coal through the crusher and
screen to the loadout area as follows: Conveyor 4 receives the ROM coal from the underground mine
portal and transfers it to Conveyor 3 which drops the coal on a stockpile. The ROM coal is then
transferred via an under-pile port to Conveyor 2 which delivers it to the crusher and screen. The crushed
coal is then transferred to Conveyor 1 which feeds the coal to the loadout bin and chute system into haul
trucks.
Barr performed opacity readings at seven emissions sources at the mine. Observations of the seven
sources were completed on May 30, 2025. All 6-minute averages were less than half of the applicable
opacity limit, so observations of sources subject to the NSPS were reduced to 30 minutes. Due to the
location of the transfer point from the mine portal to Conveyor 4 at the end of the box cut, it was not
possible to observe the transfer point. The opacity limits and highest average observed opacity for each
observed source are included in Table 1 below.
June 15, 2025
Page 3
Toble I Emery Mine Opocity Llmlts ond Hlghesl Averoge Observed Opocity
1 5-minute average
'? 6-point average
Conclusions ond Recommendolions
Observed visible emissions from all viewed sources were less than applicable limit and the Emery Mine is in
compliance with the applicable opacity limits.
According to Section 60.255(bX2) of Subpart Y, the timing of repeat performance tests is dependent on the
following conditions:
i) lf any 6-minute average opacity reading in the most recent performance test exceeds half
the applicable opacity limit, a new performance test must be conducted within 90 operating
days of the date that the previous performance test was required to be completed.
ii) lf all 6-minute average opacity readings in the most recent performance test are equal to
or less than half the applicable opacity limit, a new performance test must be conducted
within 12 calendar months of the date that the previous performance test was required to
be completed.
Conveyor transfer
points
10 0r 1 ROM convevor droo ooint
10 0r 2 Conveyor4to3transfer
point.
10 0r 3 Crusher to conveyor 1
transfer point. Process
was continuous
throughout 30-minute
observation oeriod.
10 01 4 Coal Loadout. Observed
loading of 3 trucks with
brief downtime intervals
between loading over a
20-minute period.
Crusher 10 11 5 Process was continuous
throughout 30-minute
observation period.
Screen 10 01 6 Process was continuous
throughout 30-minute
observation oeriod.
All other sources 20 02 7 Haul road. Observed 8
passes of trucks.
Sincerely,
l/il
June 15,2025
Page 4
Based on the above requirements for 5-minute observations, the next performance test is due within 12
calendar months of the date that this performance test was completed.
John C. (Kit) Pappas
Environmental Manager
Bronco Utah Operations, LLC
Figure 1: Opacity Observation Locations
Attachment 1: Tabulation of visible emissions observations
Attachment 2: Opacity observation field sheets
Attachment 3: Method 9 Certification
t,
@
Feet
0
Meters
0
A
o
tl.
Observer Location
Measurement Location
Conveyor Alignment
Municipal Boundary
County Boundary
Figure 'l
OPACITY OBSERVATION
tocATroNs
Bronco Utah Operations, LLC Coal Mine
Emery Counry Utah=FEFI_
60
----
Attqchmenl I
Tobulotion of visible emissions observolions
Bronco Utah
Visible Emissions Averases
Facility lource Date Minutes
Averate
OoaciW (%)Notes
Emery Mine toM Coal Convevor Droo Point "A"sllo/2s 1-6 Observations stopped after 30 minutes because all 6-
minute averages were equal to or less than half of
the opacity limit.
7-t2
13-18
19-24
ls-30
:onvevor 4 to 3 Transfer Point "8"sl10/2s 1-6 Observations stopped after 30 minutes because all 6-
minute averages were equal to or less than half of
the opacity limit.
7-12
13-18 0
79-24 0
25-30 0
lrusher to Convevor 1 Transfer Point "F"sl30l2a 1-6 0 Observations stopped after 30 minutes because all 6-
minute averages were equal to or less than half of
the opacity limit. See multiple source observation
form for readings and observation time details in
Attachment 2.
7-t2 0
13-18 C
19-24 c
25-30 C
Coal Loadout "D"s/3012a 1-6 0 )bserved 5 trucks being loaded during five 6-minute
)eriods during a 30-minute timeframe of this
ntermittent process.
7-t2 o
13-18 c
t9-24
25-30
Crusher "E sl30l2!r-6 Jbservations stopped after 30 minutes because all 6-
Tinute averages were equal to or less than half of
:he opacity limit. See multiple source observation
'orm for readings and observation time details in
{ttachment 2.
7-t2 1
13-18
L9-24
25-30
Screen "C"sl30l2r 1-6 Observations stopped after 30 minutes because all 6-
7-r2 minute avera8es were equal to or less than half of
the opacity limit. See multiple source observation
form for readings and observation time details in
Attachment 2.
13-18
t9-24
25-30
Pass fl
Haul Road "G"s/3012:1 f,bserved 8 passes of trucks and other equipment at
i points along the haul road.2
3
4
5
7
Page 1 of 1
Attochmeni 2
Opocity observotion field sheets
170 S Marn Street Surte 5C0
sarr Lake crty uT 84101
P 801 -333-8400
'w\1 ,! barr comBARRm1-Hour Visible Emissions Observation Form
Source Name
3ronco l,tne
JOservatron Uale/'r' >(' -' >
Start Time),Stop Trmet, 5qddress,'Locatoi [-. .
imery Deep. Bronco t ') (-t 5. (.., / t i', ,, r ,t \mrVsec 0 15 tl5 mrn/sec 0 15 30 45
lltY IL,.' -
State'
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Source tD Numbdr
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1 11
I 34
)rocess Equipment . (,. \,.. ,.' ( ' '). \
3perahng Mode
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5 1a
6 36
3ontrol Equrpment
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3perating Modb
8 38
fmrsston Point
(,,,,-l tlli- f, l' 1..,. i r
I 39
0 rl0
)islance from Observer Drrecton from Observer 1 41
2 42
-terght Above Ground
,
Herght Relatle lo Observerlr^3 43
4 41)lurne Color Plume Type continuous
luortive : rntermittenl
5 45
6 (46
rornl in the Plume at Whrch Ooacty was Determtned (trom source)
-lonzontal Drstance /' Vertrcal Distance -
7 47
8 48
Wate,Oroplets Present
no,r- yes
Water Droplet Plume is
attached -r detached, l
19 L I ((^49
20 50
3ackground Descnphon (Color)21 51
22
Sky Condrhons qmbient femperature 23 (53
21 54
11/rnd Speed /1/rnd Drrecbon -<(55
26 56
Source Layout Sketch
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sun locaftyf ilne
27 57
28 58
29 59
30 60
Avg Opacrty for Highest Period/-# of Readings Above 20ol. were
Range of Opaoty Readrngs
'"4mrmum : Maxrmurn C;
Jbserver's Name Taylon Earl
Jbser! er's StOnatyg__a__ 1..'r j'(, \-.t," . c.)
)rganization Ba.r,lr{grneenng Co
;ertfied by
Ljco, ,1. A i ualc.) .a, at) )l .-)
170 S lVarn Street Surte 500
Salt Lake CrtY UT 8,1101
P 8C1-333-8400
vvww 53[r COmND J[ hFbEDldl.( rt(re 1-Hour Visible Emissions Observation Form
Drstance from Observer )('
Source Layout Sketch
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* sun ---) wrnd X emrssion potnt
Source lD Number
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:ss Equrpment ., lOPeratlng Mode 'R'::',',:i:"'..,-.,- l; i a, ."r,,Fi,
Plume Type contnuous -
ffiDetermrned(fromsourcet | 17
al Drstance - VertJcal Dlstance
gtound Descrrptron (Colol )
Sky Condltrons lAmbrent Ternperature I 23
Avg Opacrty lor Highest Perrod
's Name Taylon Earl
Organrzation Ban Engrneerrng Co
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170 S Marn Street SLrrte 500
SaliLake Crty Ur 8.1'1C1
F 801 -333-84tC
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m 1-Hour Visible Emissions Observation Form
Addressi Location
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from Observer
rn the Plume at Whrch Ooacitv was Determlned lfrom so(lrcel
Honzontal Drstance Vertlcal Distance
Source Layout Skelch
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Source Name
Bronco Mine
lD Number .. /tt(-' lt I
mrssion Point ('.,..-" f/_.^. f, ,,, i f .-,,.--. , 1] v \-.,.
Heroht Relatve to Observer" /-. I-).'
Plume Type contnuous u
Water Droplel Plume is
anached-; detached l
Backgrotrnd Descrrptton (Color) ----l/,r\ d t,tf) lJ t^,.:
Avg Opaoty for Hrghest Penod
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# ol Readrngs Above 2001, were
c;
Range of Opacty Readrngs
Observer's Name Taylon Earl
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Organrzaion r6arr Engrneering Co
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Salt Lake Crty .]T 841C1
P 801 -333-E40C
BARR ww^ barr co'n
ffi 1-Hour Visible Emissions Observation Form
mery Deep. Bronco >9c 5 lt (r.,2,\ ;mini sec
Layoul Sketch
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ocess EquipmgU lOperatirg Mode ,t, -:,
Height Relahve to Observer--
Plume Type continuous a
Ooacfv was Determrned lfrom sorlrce)
Verhcal Dlstance
Background Descriptron (Color) i
Sky Condrtrons , lAmbtent Temperalure
# of Readings Above 209i, were
Range of Opacrty Readings
Observer's Name Tavlon Earl
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Salt Laxe Crty UT 84101
P 801-333-8400
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essi Location
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