20190730Dempsey Exhibit 3.pdf

DAVID J. MEYER
VICE PRESIDENT AND CHIEF COUNSEL FOR
REGULATORY AND GOVERNMENTAL AFFAIRS
AVISTA CORPORATTON
I4I I E. MISSION AVENUE
P . O. BOX 3727
SPOKANE, WASHINGTON 99220
PHONE: [phone], FAX: [phone]
RECEIVED
i0l9 J,JL 30 PIl 2: l8
i-., i- i,l.iiiLlU* r: i i rt; ilf;l,ihllssloN
BEFORE THE IDAHO PUBLIC UTILITIES COMMISSION
TN THE MATTER OF THE POWER COST )
ADJUSTMENT (PCA) ANNUAL RATE )
ADJUSTMENT FILING OF AVISTA )C0RPORATTON )
CASE NO. AVU-E-L9-O9
EXHIBIT NO. TCD-3
THOMAS C DEMPSEY
FOR AVISTA CORPORATION
TALEN Gordon Criswell o Director, Environmental & Compliance
PO Box 38 o 580 Willow Avenue o Colstrip, MT 59323
[phone]. gordon.criswell@ta lenenergy.comM O N TA N I\
September L7,2018
David L. Klemp
Air Quality Bureau Chief
Montana Department of Environmental Quality
Sent via email to: [e-mail]
Dear Mr. Klemp,
ln response to your August 3t,20t8letter requesting information related to compliance with the
Mercury & Air Toxics Standard for Colstrip, the following response is provided. Each requested item
identified in the 8/3U18 letter is stated first, followed by the response.
1. The daily calcrrlatiort of the u,eigltted 30-boilet operntiug day rolliug avel"ge ernission rate
CVAER) tbr each of Units 1-4 as specitied byEquation 2a at $63.10009(bX2), t}onrSeptember
8,2016 to present. The calculation nnrst identi$ the eurissions {ate used tbr each uuit ancl the
soruce of the 30-day total heat input (HI) tbr that trnit tbr each daily calculation. Provide a
description of dre calctrlation urethoclology, ilcluding rationde tbr dre chosen nredrodology,
and citation of applicable rules to iusti$ tlte rnethodology used.
A. The daily calculation of the weighted 30-boiler operating day rolling average emission rate
(WAER) for each of Units 1-4 as specified by Equation 2a at 63.10009(b)(2), from September 8,
2016 to September 72,2018 is provided in the attached excel spreadsheet titled Colstrip PM
MATS DEQSubmittal 2018-09-17, tab DEQ ltems 1&2. Note thatthe calculation is not
performed "for each of Units 1-4", but data from each of Units 1-4 is used to calculate site-wide
weighted 30-day rolling average emission rate per Equation 2a and it is identified in column R.
B. The emission rate used for each unit, which is the most recent MATS Method 5 stack test result
for that unit for each day, is identified in columns F-1.
C. The daily heat input for each unit is identified in columns J-M and the rolling 30-boiler operating
day heat input for each unit is identified in columns N-Q. Note that the spreadsheet also
contains heat input data from 8/9116 through 917 /t0 so that a rolling 30-day average could be
caf culated starting September 8,20L6. These data are in gray cells.
2019 ldaho PCA - Dempsey Exhibit No. TCD-3 Page 1 of8
D. The relevant equation for calculating WAER is Equation 2-A from 40 CFR 63.10009. The equation
as provided addresses'both calculations for pollutants using continuous monitoring (the terms
that include a summation from i=1 to p, on the left side of the equation) as well as for pollutants
using stack testing (on the right side of the equation). For these calculations which are based on
stack testing, only the right side of the equation is relevant.
ll.[&r0lsn x firn,fl r ffirClen xntr)(f;q.2a)TI'JfE =,Pr,)t + E?rfitit
Where:
llerr = hourly emlsslon ra,te (e.o.. ltvMMBbu.
lh,'}11!'h) fronr unlt I'E CEMS for t'he pre-
cedlng 80-croup botl€r opgraclns days,
R.nrr = hourly heat tnput or gnosE output fronr
unlt I for th€ precedlnc glgroup bouer
opemtlnr dave.
p = nurnbBr of EOLis tn smlsslonB averaglng
sroup t'h&t roly on CDME or sorbsnt trap
monltorlnE.
n = number of hours thet hourly r&tas arg
collected over SGsoup bollor operattnf
days.
t'er, = gploloni rate from rnoEt rcc€nG eml6-
slons test of unlt, I ln tsrms of lhteab
,npu[ or thtross output.
Rh = Total beat lnput or grors outpuL of unltt for Ehe precedlnr il0-Dotler op€ratlns
dal's. arrd
m = number of EGUs ln emls8lons aysraglnE
rroup that rels on emisslons tostlng.
a. The numerator
i. First multiplies two terms
7. Teri, the unit-specific emission rate from the most recent emissions test
in lblMMBtu
2, Rti, the unit-specific heat input in MMBtu for the preceding 30 boiler
operating days
3. The product of which equals mass emissions for that unit (lbs.)
ii. Then sums the mass emissions for each unit across the four units
b. The denominator is simpler and just sums Rtifor each unit across the four units
(MMBtu's)
E, The 30-boiler operating day heat input is developed consistent with the definition in 40 CFR
63.10042.
Boiler operating day means a 24-hour period that begins ot midnight and ends the following
midnight during which ony fuel is combusted ot any time in the EGU, excluding startup periods or
shutdown periods. lt is not necessary for the fuel to be combusted the entire 24-hour period.
a. Boiler operating day is determined using hourly data for each unit
b. Hours when the unit is in startup or shutdown are excluded consistent with the
definition
c. To determine whether any fuel is combusted, both heat input and power output values
are reviewed on an hourly basis. ln a day, if there is an hour that is not startup or
shutdown which has a non-zero value for either power output or heat input (or both),
that day is a boiler operating day.
d. The 30-boiler operating day heat input value for a unit is calculated by summing the
calculated daily heat input values for the current (or most recent) boiler operating day
plus the 29-preceding boiler operating days.
2019 ldaho PCA - Dempsey Exhibit No. TCD-3 Page 2 of 8
2. Records of the daily heat input (HI) tbt each of Units 1-4 ti'onr Septernbet 8,2076 to preseut.
Pleasc cleatly denronstrate hov, drese daily HI valtres are used in calculatirlg the \i/AER.
The daily heat input (Hl) for each of Units 1-4 from September 8, 20L5 to September 12, 2018 is also
provided in the attached spreadsheet columns J-M. A daily heat input value is presented for a unit, if
there was at least one hour of non-startup/shutdown heat input within that day. Each day's calculated
30-boiler operating day (BOD) heat input for a unit (in columns N-Q for Units L-4, also referred to as Rti
in equation 2a, is the total of the preceding 30 heat input values for the unit corresponding to the unit's
preceding 30 boiler operating days (i.e., the last 30 days when there is at least one hour of operations
under non-startup/shutdown condition). To sum values for the preceding 30 boiler operating days for a
unit, the 30 boiler operating days do not have to be consecutive.
3. Records of the occuuelrce and dtuatiou of each starnrp and/or shut do*,u tbt each of Units
1-4 ti'orn Septernber 812016 to present. Provide a natrative description of horvTaleu conrplies
with the 'nvodr practice standards of N{ATS durirg these occtrlrences and denronstrate how
drese situations ate addressed in the WAER calculations.
The occurrence and duration of each startup and/or shut down for each of Units 1-4 from September 8,
2016 to September 12,20t8 is provided in the attached spreadsheet titled Colstrip PM MATS DEQ
Submittal 20L8-09-17, tab DEQ ltem 3. The data in thls tab are on an hourly basis and each startup
and/or shut down hour is identified by a 1 designation. Unit 1 startup times are found in column E and
Unit 1 shut down times are found in column D. Unit 2 startup tirnes are found in column I and Unit 2
shut down times are found in column H. Unit 3 startup times are found in column M and Unit 3 shut
down times are found in column L. Unit 4 startup times are found in column Q and Unit 4 shut down
times are found in column P.
The Colstrip Steam Electric Station complies with the MATS work practice standards during startup and
shut down by taking the following actions:
All Continuous Emission Monitoring Systems (CMS) are operated during startup and shut
down periods.
Clean fuel, Liquefied Petroleum Gas (LPG) for Units 1&2 and Low Sulfur #2 Diesel Fuel Oil for
Units 3&4, are used for startup.
When firing on coal, all the applicable control technologies (Low-NOx systems, Mercury
Control systems, and Wet Venturi Scrubber systems) are in operation.
Records of startup/shut down periods are maintained.
Dates of most recent boiler tune-ups and burner inspections are provided in the MATS Serni-
annual Reports submitted to MDEQ.
Periods of startup and shut down are not included in the site-wide weighted average emission rate
(wAER).
2019 ldaho PCA - Dempsey Exhibit No. TCD-3 Page 3 of 8
4. A description of all non-rotrtirre rvor* peltbnned, any operatioual changes, arxl any chauges
to the coal supply or quality at Units 3 and 4 tbr the period between the tbumh quartet 2017
and the second qualter 2018 drat nray have irnpacted the Pi\{ errrissious pertbmrance.
A review of activities from 4ft quarter 2OL7 lo 2nd quarter 2018 was conducted with engineers,
operations, and.maintenance; including the boiler and scrubber crews, to get a thorough understanding
of any changes that may have impacted the PM emissions performance.
Coal supply or quality - all coal burned from 4th quarter 2017 through 2nd quarter 2018 were from the
normal permitted mine areas. Coal quality analysis was reviewed including ash content, heating value,
moisture, sulfur and ash characteristics. The coal quality varied during this period but was within
contract specifications.
Relevant work and Operational changes between 4th quarter 2077 and 2nd quarter 2018
Scrubber makeup water (pond return wafer) increased in solids concentration for two
reasons;
o Pond return level (3&4 EHP B Cell) was low due to forced evaporation of pond water
during 2Ot7 to eliminate water in the ash ponds and help ensure protection of
groundwater. This level was raised to provide required make-up volume by
transferring water from the 3&4 EHP F Cell which contained higher solids.
o Additional water was transferred from the 3&4 EHP F Cell (higher solids) to pond
return (3&4 EHP B Cell) to facilitate liner repairs at the 3&4 EHP F Cell and help
ensure protection of groundwater.
Low-NOx tuning at Units 3&4 boilers - optimizing the SmartBurn Low-NOx system to
rninimize NOx emissions.
Although neither the continuous Opacity Monitors nor the PM CEMS provided an indication
of an increased PM emission level across the time frame indicated, it appears that the
characteristics of the PM had changed. The change, potentially the particle size distribution
in the stack, appears to have changed the ratio of PM mass to detected concentration, i.e.,
the correlation curve of the PM CEMS. ln other words, particles of a different size with
more total mass may have been emitted, but the Opacity Monitors and PMCEMS were still
"seeing" the same concentration in the stack gas. Colstrlp is still investigating this issue to
determine what could be done to prevent it from happening in the future.
2019 ldaho PCA - Dempsey Exhibit No. TCD-3 Page 4 of 8
5. A description of all iuspection, rnaintenance, and operation activities associated rvith the
boilers and verrturi scrubbers since dre deviations.
Quarterly MATS PM Test results were received on June 28,20L8 that indicated a deviation of the MATS
PM limit. MDEQ was notified on June 28 and Unit 3 was removed from service on June 28 and Unit 4
was removed from service on June 29. Talen proposed and MDEQ acknowledged that llmited operation
of Units 3&4 for evaluation of a corrective action or for data gathering related to potential corrective
action was a prudent approach to solving the issue.
An extensive inspection of the Units was conducted including the coal mills, boiler, ductwork, air
preheater, scrubbers, and the stack. Cleaning, adjustments, and repairs were conducted as needed.
Areas of inspection included:
CoalMills
Classifiers
Air flow controls
Windboxes
Separated Over Fire Air (SOFA) dampers
Top Over Fire Air (TOFA) dampers
Burners
Ductworko Air Preheater
o Scrubber inlet ducts
o Scrubber outlet ducts
Scrubbers
Venturi/Plumb Bob area
Venturi/Plumb Bob sprays
Venturi & Absorption pumps
Absorption sprays
Wash Trays
Wash Tray sprays
Mist Eliminators
Mist Eliminator sprays
Reheaters
Reheater soot blowers
liner
Unit 3 was off from June 28 - July 8 for this work, Unit 4 was off from June 29 - July L7 for this work. No
major equipment issues were identified during these outages. Additional outages and inspections
continued to occur as needed during the trouble shooting period as corrective actions were evaluated
and implemented.
o
o
er
o
o
o
o
Boil
o
o
o
o
o
o
o
o
o
o
Stack
o
2019 ldaho PCA - Dempsey Exhlbit No. TCD-3 Page 5 of I
Four main areas were investigated to determine and address the cause of the 2nd quarter MATS PM test
results on Units 3&4:
Compliance Test Method
FuelQuality
Boiler Combustion
Scrubber Performance
Nationally recognized expertise was brought on-site to help conduct the investigation and implement
corrective actions:
AECOM - overall root cause investigation & scrubber expertise
GE/Alstom - boiler combustion expertise
SmartBurn - boiler combustion expertise
Power Technical Services - boiler combustion expertise
Munters - scrubber mist eliminator expertise
Bison Engineering - stack testing expertise
Air Control Techniques - stack testing & pollution control expertise
Compliance Test Method
Qualified Source Testing lndividuals (QSTI Certified) conducted the PM tests. They verified that the
proper method, procedures, QA/QC, and calculations were used. An audit of the testing was conducted
following the EPA Air Emissions Testing Body (AETB) Manual. lndependent side-by-side testing was
conducted for single run tests, with consistent results between test groups.
FuelQuality
Coal analysis including proximate analysis and ultimate analysis was reviewed. While variations in coal
quality were observed, the results were within contract specifications.
Boiler Combustion
Coal mill performance was evaluated and compared to target guidelines related to coal grind (fineness)
as well as fuel distribution in the boiler. Minor adjustments were made to some mills to rneet the target
guidelines. Some fouling/slagging was observed in the boiler which was cleaned up and adjustments
and minor repairs were made to the furnace to help reduce slagging/fouling. Boiler conditions were
evaluated and adjusted to establish a focus on overallfurnace condition compared to the low-NOx focus
that had recently occurred. Boiler conditions were also evaluated to ensure excess SO3/acid mist, a
condensable PM that could affect the results, was not being formed and emitted.
Scrubber Performance
The entire scrubber system from the inlet ductwork to the stack were inspected. Cleaning, adjustments,
and repairs were completed as necessary. Evaluation of scrubber performance focused on three maln
areas - liquid spray flow, flue gas flow, and scrubber chemistry.
2019 ldaho PCA - Dempsey Exhibit No. TCD-3 Page 6 of 8
Liquid spray flow - the wet venturi scrubbers remove both particulate and SO2 and proper spray flow to
the different sections of the scrubber are important, The scrubber sprays include the venturi sprays,
plumb bob sprays, absorption sprays, wash tray sprays, and mist eliminator sprays. All sprays were
inspected and evaluated during operation to verify proper spray. Adjustments were made (flow orifices
installed) to the venturi/plumb bob sprays to provide a more effective balance of sprays in this area.
This venturi/plumb bob section of the scrubber is where most of the particulate removal occurs.
Flue gas flow - overall flue gas flow and proper distribution of the flue gas is important to etfective
scrubber operation. The mist eliminator section of the scrubber controls carry-over of droplets from
the wet scrubbing process. These droplets contain solids which can contribute to particulate emissions.
Testing of the mist eliminator section of the scrubber indicated that, although meeting manufacturer
specifications, flue gas flow through the mist eliminators was not optimally balanced, resulting in areas
of higher flows. A mist eliminator flow distribution plate was installed on all scrubbers to better balance
the flue gas flow through this area of the scrubber and help keep velocities at a level for proper mist
eliminator performance. A more detailed description of this work is described in the De Minimis
Notification for Changes to Colstrip Units 3&4 Scrubbers - Scrubber Flow Distribution Plates that was
submitted to MDEQon August 24,2018 (this notification is attached).
Scrubber Chemistry - A review of scrubber chemistry, primarily scrubber solids, was conducted to
evaluate previous levels in comparison to current levels. There are two separate scrubber water
supplies that were evaluated, scrubber recycle tank water and scrubber wash tray water. Historic levels
of scrubber recycle tank solids range from 25-30% solids. Levels in early 2018 were up to 35% solids.
Historic levels of scrubber wash tray solids range from LO-!S% solids. Levels in early 2018 were up to
17% solids. Testing of scrubber chemistry indicates that a target of 20-25% recycle tank solids and L0-
15% wash tray solids is good point that balances the benefits of lower solids in regards to carry-over and
PM emissions with the benefits of higher solids that help prevent scale buildup which results in
equipment shutdown for cleaning. Scrubber additives were also tested to determine if scrubber
performance could be improved, with the results from that testing indicating little to no improvement in
scrubber performance.
6. Records of the date and tinre (start and errd) tbr each period of norrcompliancc ftom.|true 21,
2018 to pr-esent.
MATS PM Deviations are recorded for daily rolling 30-day site-wide average above 0.030 lb/mmbtu from
June 21, 2018 through September 5,20t8. Data provided in response to Request for lnformation #1
shows compliance with the site-wide MATS PM limit from September 6,2078 to present.
Unit 4 MATS PM Compliance Test conducted on 9/61t8 demonstrated a PM emission rate of 0.02L
f b/mmbtu. Unit 3 MATS PM Compliance Test conducted on 911U1,8 dernonstrated a PM emisslon rate
of 0.O24lblmmbtu.
2019 ldaho PCA - Dempsey Exhibit No. TCD-3 Page 7 of 8
lf you have any questions regarding this response to your information request, please don't hesitate to
contact me at 406-748-5002 or sordon.criswel [e-mail].
Sincerely,
;{o*^ h,.*t{
Gordon Criswell
Director, Environmental & Compliance
Talen Montana
2019 ldaho PCA - Dempsey Exhibit No. TCD-3 Page 8 of 8