SIERRACLUBFOUNDED1892January7>2016GuyDonaldson>ChiefAirPlanningSectionU.S.EnvirorunentalProtectionAgency,Region61445RossAvenue,Suite1200Dallas>Texas75202-2733REC...IRr16J-8PH5:24Re:ReviewofSulfurDioxideAirDispersionModelingSubmittedbyNRGPowerLLCfortheW.A.ParishElectricGeneratingStationDearSectionChiefDonaldson:OnSeptember17,2015,andagainonDecember14,2015,SierraClubsubmittedairdispersionmodelingconductedbyWingraEngineering,S.C.thatdemonstratedthatsulfurdioxide("S02")emissionsfromtheW.A.ParishElectricGeneratingStationinThompsons,TexascausedownwindS02ambientairconcentrationstoexceedthe75partsperbillionNationalAmbientAirQualityStandard("NAAQS"),whichtranslatesto196.2microgramspercubicmeter("Jlg/m3'}Inparticular>themodelingdemonstratedthattheW.A.ParishplantcausesdownwindS02concentrationsashighas231.2Jlg/m3.Accordingly>theareasurroundingW.A.ParishshouldbedesignatednonattairunentunderEPA's1-hourS02NAAQS.OnJuly24>2015>however,NRGTexasPowersubmittedmodelingconductedbyathird-partyconsultant>suggestingthattheW.A.ParishpowerplantdoesnotcauseexceedancesoftheS02NAAQS,andthereforeshouldnotbedesignatedasnonattairunent.Enclosed,pleasefindtheresultsofanindependentreviewofNRG>smodelinganalysesconductedbyH.AndrewGray,Ph.D.,ofGraySkySolutions.Dr.Gray'sreviewconcludesthatNRG'smodelinganalysisreliesonincorrectstackparametersandinappropriatesurfacedatainputs.CorrectingtheseerrorsresultsinS02concentrationsthatareapproximately35%higherthanNRG'smodelingpredicts.Infact,usingtheappropriatestackparametersandtherecommendedsurfacecharacteristicswouldincrease

# Mr. Don aldso

n

, Ch ief

. Air Plann
ing
Se ction

, U.

S

. E n v ironmental

Prote

c tio

n Agency, Region

6 January

7

, 

# 2016 Page

2 the mode
led design value

to at least 

# 221

!lg

/ m

3 

# - well beyond

the acceptable NAAQS le vel.
As Sierra Club's previously submitted

m

o deling demonstrates,

those exceedances are even grea ter when nearby sources

of S02
are taken
into account. Accordingly,

the area surrounding

W.A. Parish

s h ou

l d be designated nonattainment

under

the NAAQS. W

e urge EPA

to co

n

s
i der

t hi

s in formation

as



# it undertakes

area designations

in Texas

for

t he 

# 2010 revised

pr

i mary

S0

2 NAAQS.

This information

is being prov

i ded

to both EPA's Office

o f Air Quality Planning

and

St andard

s and Region

6

. In the meantime,
please

le

t me know

if

I can provide

any addition

a
l information. T hank you for your attention

to and consideration

of this matter,

and please

do not hesitate

to conta

ct me

if you would
like

to disc uss further. Joshua: Smith Staff

A mey Sierra Club 85 Second

St.

, Second

F

l oo

r San Francisco,

CA 94108 P h one: (415)
977

- 5560 Fax: (415) 977-5793 jo

s hua

.s mith
@s ierraclub.orgMEMORANDUMTo:EnvironmentalProtectionAgency,Region6andOfficeofAirQualityPlanning&StandardsFrom:H.AndrewGray,Ph.D.,GraySkySolutionsDate:January7,2016Re: ReviewofNRG'smodelingofParishS02emissionsIrecentlyreviewedtheS02modelinganalysisconductedbyNRGfortheW.A.ParishElectricGeneratingStationlocatedinThompsons,Texas.ThemodelinganalysiswasperformedusingtheAERMODdispersionmodel(anditsmeteorologicalpreprocessorsAERMINUTEandAERMOD).Thereviewconsideredwhethertheappropriatedatawereusedandwhethertherecommendedmodelingprotocolswerefollowed.1AnumberofsensitivitytestswereperformedusingNRGmodelingfilestosupportmyobservations.Asetofmodelingfiles2wasobtained(butnosummaryreportwasprovided),whichincludedinputandoutputfilesforAERMODandanumberofpreprocessors,includingAERMINUTE,AERMET,AERSURFACE,AERMAP,andBPIP.Themodelingprocess,assumptions,inputdata,andoutputswereexamined.Abriefsummaryofmyfindingsispresentedbelow.StackparametersNRGmodeledParishUnit7withastackdiameterof7.315m(matchingUnits5and6).Visualinspectionusingsatelliteimages,however,indicatesthattheUnit7stackhasasmallerdiameterthaneitherUnit5or6;thediameteroftheUnit7stackisapproximately 6.7 m.Asdiscussedbelow,theuseofalargerdiameterwithinAERMODincreasestheestimatedmomentumfluxfromthestackwhichresultsinahighercomputedplumerise,andmateriallylowermodeledpeakambientconcentrationsforthisunit.3NRGusedvariablestacktemperaturesandvelocities,whichvariedhourlydependingontheemissionrateandambientconditions.Forexample,NRG'sstacktemperatureforUnit5variedfrom266to496K,withathree-yearaverageof416K(standard1AERMODUser'sGuide;AERMODImplementationGuide;USEPAAppendixWto40CFRPart51,ApplicabilityofAppendixWModelingGuidanceforthe1-hourS02NationalAmbientAirQualityStandard(August23,2010);ModelingGuidanceforS02NAAQSDesignations;andUSEPAS02NAAQSDesignationsTechnicalAssistanceDocument(December2013).2ParishModelingArchive,datedSeptember2015(filestransferredNovember20,2015).3ComparisonofmodelresultsforUnit7usingstackdiametersof6.7m and7.315m showedthatthemodeleddesignvalueforthesmallerstack(6.7mdiameter)was10percenthigherthanthedesignvalueforthelargerstack(diameter=7.315m).1deviation=47K).NRG'sstackvelocityrangedfrom0to37.4m/sforUnit5(thezerovelocityvalueswereduringshutdownperiods),withathree-yearaverageof23.7m/s(notincludingzeroemissionhours;standarddeviation=7m/s).ComparingAERMODmodelresultsusingconstantstacktemperatureandvelocitytoNRG'svariablestackdatademonstratedthattheuseofconstantstackdatahasanegligibleeffectofthemodelresults.4ReceptorsNRGusedasetofgriddedreceptorswith100mspacingintheareasurroundingthepeakconcentrations(withadditionalcoarserspacedreceptorsfurtherawayfromthesource).5NRGusedtheAERMAPpreprocessorprogramtodeterminereceptorelevations.NRGusedaflagpoleheightof0.0mforallreceptors.TestingoftheAERMODmodelusingdifferentflagpoleheights(1.5 mand0.0m)showedthattherewasverylittledifferenceintheestimatedpeakconcentrations.6MeteorologicalDataThemeteorologicalpreprocessor,AERMET,requireshourlysurfacemeteorologicaldataandupperairwindandtemperatureprofiledataasinput.Inaddition,theAERMINUTEprogramisusedtoaugmentthehourlywinddatawithone-minuteASOSwinddata.NRGusedhourlysurfacedataandone-minuteASOSwinddatameasuredattheHoustonSugarLandMemorialAirport,located16kmnorthoftheParishfacility.NRGalsousedtheupperairsoundingdatafromtheLakeCharles,LAAirport.ThesetwoairportsarerecommendedbyTCEQasthesourceofAERMETmeteo"rologicalinputdataforsourcesinFortBendCounty.7AERMETcomputesanumberofmicrometeorologicalparametersthatarerequiredbyAERMOD,suchasthefrictionvelocity,Monin-Obukhovlength,convectivevelocityscale,temperaturescale,mixingheight,andsurfaceheatflux.Inadditiontothehourlywindspeed,winddirection,temperatureandcloudcoverdata,AERMETrequires4ThemodeleddesignvalueforUnit5usingaconstantstacktemperature(439.8K)andvelocity(25.9m/s)waswithin0.02percentofthemodeleddesignvalueforUnit5 usingNRG'svariablestackdata.Themodeledthreeyearmaximumconcentrationwasapproximately7percentlowerwhenusingtheconstantstackdatarelativetothemodeledmaximumusingvariablestackdata.5NRGusedatotalof6,909receptors.6AERMODwasrunforParishUnit5usingboth0.0mand1.5mforthereceptorflagpoleheights.Raisingtheflagpoleheightfrom0.0mto1.5mincreasedthemodeleddesignvalue502concentrationfrom49.33llg/m3to49.47J.1g/m3(adifference oflessthan0.5percent).Thethree-yearmaximum502concentrationincreasedfrom98.20jlg/m3to98.46Jlg/m3•7http://www.tceq.state.tx.us/permitting/air/modeling/aermod-datasets.html2surfacecharacteristicstobeinput,suchasalbedo,Bowenratio,andsurfaceroughness.NRGusedtheAERSURFACEprogramtodevelopthissurfacecharacteristicdataforinputtoAERMET.NRGsupplementedtheAERSURFACEcalculationswiththeirown"Wedge"approachtocomputethesurfaceroughnessdata(usingNRG'sownprograms,CR_BLN,FIX-LU,andCLC_ZO).NRGusedtheTexasland-usedataset8,togetherwiththesurfaceroughnessassignmenttable(z0vs.USGSNLCD92land-usecategories)fromAERSURFACEtodevelopweightedaveragemonthlysurfaceroughnessvaluesforinputtoAERMET.ForitscenterofthestudyareainitsAERSURFACEcalculations,NRGusedthelocationoftheParishfacility,whichis16kmtothesouthoftheSugarLandAirportmettowerthatNRGrelieduponforsurfacemeteorologicaldata.9AccordingtotheAERSUFACEUser'sGuide10,however,"[t]hecoordinatesinputtoAERSURFACE[forthesitecenter]shouldbebasedonthelocationofthemeteorologicaltower(measurementsite)forthemeteorologicaldatatobeprocessedwiththeoutputsurfacecharacteristics."Theuseofmeteorologicalandsurfaceroughnessdatafromdifferentlocationscreatesamismatchbetweenthemeasuredwindandtemperaturedataandthelandusedata.TheAERSURFACEUser'sGuideacknowledgesthedifficultyofestablishingrepresentativedataforthemodeledregion:"DeterminingeffectivesurfacecharacteristicsforthepurposeofprocessingmeteorologicaldataforusewiththeAERMODmodelpresentsmanychallenges.AERMODisasteady-stateplumemodelwhichassumesspatiallyuniformmeteorologicalconditionsacrossthemodelingdomainforeachhourofmeteorology,whilelandcoveracrossthedomainistypicallyveryheterogeneous.AsoundunderstandingoftheimportantphysicalprocessesrepresentedintheAERMODmodelalgorithms(Cimorelli,etal.,2004)andthesensitivityofthosealgorithmstosurfacecharacteristicsisneededinordertoproperlyinterprettheavailabledataandmakeanappropriatedetermination."TheAERSURFACEUser'sGuidestronglycautionsagainstusingtheincorrectlocationforthecenterpointforsurfacecharacteristics:"NOTE:SignificantdiscrepancieshavebeenidentifiedbetweenstationcoordinatesreportedbytheNationalClimaticDataCenter(NCDC)andtheactuallocationofthemeteorologicalinstrumenttowerforNationalWeatherService(NWS)sites.Discrepanciesofseveralhundredmeters8texasse NLCD092800flat.bin9NRGtheofMayandSeptemberinitssummerclassification(thedefaultmonthlyassignmentsforsummerareJunethroughAugust).10AERSURFACEUser'sGuide,U.S.EnvironmentalProtectionAgency.OfficeofAirQualityPlanningandStandards.ResearchTrianglePark,NorthCarolina,EPA-454/B-08-001,January2008.3up to

a few kilometers

are common,

wh

i ch could significantly compromise the representativeness

of AERSURFACE calculations, especially

for surface

roug hness. Users

are encouraged

to verify

the coordinates

of the meteo

r ological tower before applying AERSURFACE."
(emphasis added). Here, NRG

' s select

i on of the Parish

l ocation

as the cen ter
of the study area

, rather than the recom

m
e n ded

l ocatio

n of the meteorological

tower (Sugar
Land Airport)

, where

t h e surface
data were measured

, had

a substant

i al effect

on the computation

of the surface characteris

ti cs that were input

to AERMET

. The Bowen ratios computed

by NRG

, us

i ng Pa

r ish as the center point,

are between

25 and
60 percent higher than would

be obtained
using Sugar Land

as the center point

in all months except January,

June and July.

In those three months,

in which NRG selected

the dry option

(all other months were wet

or average), NRG's Bowen ratios

are
30
to 40 percent higher than would

be obtained

using Sugar Land (using

the average option).

The monthly albedo values estimated

by NRG were

all slightly lower than those obtained

with Sugar Land Airport as the center point. However

, the most

s

i gn

i ficant differences between
using Parish and Sugar Land

as

t he center point

, are the resulting surface roughness lengths

. The surface roughness

length

(zo) values

that are input

to AERMET

are

a weighted average

of

t he NLCD92

zo val ues

, we

i g h ted
by the proportion

of land use categories

i n each sector.

The weighted average surface roughness
values

that NRG input

to AERMET

are much higher than would have been

be obtained

if the Sugar Land Airport location were used instead

, as shown

in Figures

1a and

1b

. 11 The average surface ro

u ghness

l ength

a c ross the Sugar Land data
set

( Figure

1b)

is

0

. 09

m

, w hereas NRG

' s average surface roughness

, using Parish

as the center

po

i nt (Figure

1 a

),

i s
0

. 25

m

, almost

3 times

as

la

r ge as the Sugar Land average

, with many

of the Parish (NRG) values being more than
ten times

the corresponding

Sugar Land values

. 11 Th

e surface

rou

g h n ess da ta in Figure

lb follows

the

d e

f a u lt monthly assignment

s. 4Surface

Rou ghn ess

{z

0 ), us
in g P arish {NRG) 0.6 0.5 0.4 0 .3 0 .2

Ill

Ill

Ill

I l l

Ill

Ill

Ill

Ill

Ill

Ill

Ill

Il

l 0.1
0 JAN

FEB

MAR

APR

MAY

JUN

JUL

AUG

SEP

OCT

NOV

DEC • Mont

h

, Sector Figure

1 a. Surface Roughness

(z

0
) Computed

by NRG, and input

to AERMET (grouped

by month

and sector)

, using Parish

as the Center Point. Surface

R oug
hn ess

(z

0 ), us in g Sugar Land Airport 0

. 6 0.5 0.4 0 .3 0 .2 0

:

ll
l dill1111

I ll dil

l t111

I ll tiiiJIJIIJJitiJJJIJJ

t lllt

J IIJJiil

11

1 111 JAN

FEB

MAR

APR

MAY

JUN

J UL
AUG

SEP

OCT

NOV • M

o nth, Secto

r

llhlllhl

ll DEC Figure

1 b. Surface Roughness

(z

0

) (grouped

by month

and sector), using Sugar Land Airport

as the Center Point. NRG

' s se

l ection

of mismatched
surface

and meteorological

data had

a significant

effect on the dispers

i on model results. Higher surface roughness lengths

r esu

l ted

in higher estimated mixing heights
(due

to increased vertical

d

i spersion)
within AERMET,

wh

ic h in tu rn

, resu lted

i n lower modeled

S02 concentrations

within AERMOD. Comparison

of NRG

' s AERMET

data developed

using Parish

as the center point (including

the surface 5roughnessvaluesfromFigure1a)withanAERMETdatasetdevelopedusingthesamesurfacedataandupperairmeteorologicaldata,butusingSugarLandAirportasthecenterpoint(andtheresultingsurfaceroughnessheightsshowninFigure1b)revealsthattheNRGdataexhibitedsignificantlyhighermixingheights(butidenticalwindspeedsandtemperatures).TheprevalenthighermixingheightscomputedbyAERMETinNRG'smodelinganalysisusingParishasthecenterpointduringthedevelopmentofthesurfacecharacteristicsresultedinmuchlowermodeledpeakconcentrationimpactsthanwouldhavebeenobtainedifSugarLandAirportwereusedasthecenterpoint.Asatest,theAERMODdispersionmodelwasrun(forParishUnit5)onceusingNRG'sAERMEToutputdataandthenasecondtimeusinganAERMETdatasetthatwasdevelopedusingSugarLandAirportasthecenterpoint.12TheAERMODmodeling,usingthelowermixingheights(whicharelowerduetoadistinctlydifferentsetofsurfacecharacteristics,andtoafarlesserextentduetoaslightlyhigher anemometerheight),resultedinadesignvalueS02concentrationthatwas31percenthigherthanwhenusingNRG'sAERMETdata.13BuildingDownwashNRGusedtheBPIPprogram(whichutilizesthePRIMEalgorithm)todevelopthenecessarybuildingdownwashparametersforeachofthemodeledParishunits.TestingofthemodelforParishUnits5and7withandwithoutbuildingdownwashshowedthattherewerenodifferencesbetweenmodeledconcentrations.14Themodeleddesignvaluesandallotherpeakconcentrationsforthemodelingwithoutbuildingdownwasheffectswerecompletelyidenticaltothemodeledresultswiththebuildingdownwashincluded.Thereforethemodelingofbuildingdownwasheffectsisnotneededforthismodelapplication.BackgroundConcentrationsBackgroundconcentrationscanbeprovidedtotheAERMODmodeltoaccountfornonmodeledsourcesofS02thatmayalsoimpactthereceptorlocations.Thebackgroundconcentrationsareaddedtothehourlymodeled concentrationswithinAERMOD.Ifbackgroundconcentrationsareusedandtheresultingmodeleddesignvalue12Theanemometerheightwassetto10.0mfortheSugarLandAERMETruns,and7.62mfortheNRGAERMETruns.Allotherinputdatawereidenticalotherthanthesurfacecharacteristics.TestingoftheAERMETpreprocessingprogramshowedthatincreasingtheanemometerheightfrom7.62mto10.0mresultedinslightlylowermechanicalmixingheights(theconvectivemixingheightswereunchanged).13Thethree-yearmaximumconcentrationestimatedbyAERMODusingtheSugarLandAirportAERMETdatawas12percenthigherthanthethree-yearmaximumconcentrationestimatedbyAERMODusingNRG'sAERMETdata.14Thestackheightsexceedtheminimumheightforwhichbuildingdownwashhasaneffectonthetransportoftheemittedplumes.6concentrations

are compared

with the acceptable

1-hour
S02 NAAQS

level
(75 ppb

= 196.2 IJQim\
then

t h e background effectively
lowers

the acceptab

l e impact from
the modeled source(s). T he background concentrations

are supposed

to represent "clean" up-wind condit

i ons. Measurements

from

a nearby

upw

i nd area can
be used

to determine approp

r iate backg

r ound levels

. Somet

i mes

, a baseline

cor

r espondi

n g to the typica

l lower-end concent

r ations

can

be developed

from monitoring

from the edge

of

a

" polluted

" area. Wind direction

data can also

be used

to isolate measured concentrations

from periods w

h en there was very

litt

l e contribution

from nea

r by sources. NRG used seasona

ll y variable diurna

l p

r of

il es for the background concentrations,

as shown

in

F

i gure

2. The background concentration

prof

il es were developed

(using NRG

' s own prog

r ams, PRE

P _S02
and CRBG_S02)

from data collected

at

I taly

T X, located about
320
km WNW

of the Parish

faci

l ity. As can
be seen

in Figure

2, the NRG diurnal profiles include

a significant amount

of variation between

day and night

, especially

in

t he

w

i nter and autumn months.

The background

S02 concent

r ations ranged
from

1.4
to 16.9 IJQ/m

3

, with

an average

of

4

. 9 IJQ/m

3

. Despite

the occasiona

l higher values, overall these background

levels

are significant

l y lower than the lowest measured

des

i gn value concentration

for 2011-2103

in Texas

15 (7.8 1Jg/m

3

, measured

in El Paso County).

16 Background concentrations

are added

to the impacts
from
the modeled sources.

In terms

of

a demonstration

of atta

i nment
with the

1

- hour S02 NAAQS,

the choice

of background

l evels

is only importa

n
t if the design value

for

t h e modeled sources

is jus

t be

l ow the NAAQS

leve

l (75 ppb

= 196.2 1-Jglm\

in which case
the selection

of the background

l e vel will have

a direct impact

on the pred

i cted NAAQS compliance. 18 1 6 14 12 10 8 6 **~**

I 1

I

I 2

3

I

I

I 4

5

6

7 NRG Background

50

2 Concentration I

I
I

I 8

9

10

11

12

13

14

15

16

17

1 8

1 9

2 0

2
1

2 2 2

3 • Wi nt

e

r Spring

S u m mer

F all Figure

2. Background

50

2 Concentrations

Used

in the NRG Modeling 1 5 http

:/ /www.

epa .gov/airtrend

s /values.html

I 24 16 The med

i an

o f t he 48 seasona

ll y and diurnally varying

NRG backg

r ound
con

c entration

s is
4

. lllg/m

3

. Only

15 out of the
48 value

s ar

e higher than the

El Paso County value

of 7.8 11g/m

3

• 7

# Conclusions To evaluate

t he NRG modeling

of the Parish facility,

I used EPA

' s modeling guidance and the AERMOD dispersion

model

i tse

l f to assess

the model

' s sensitivity

to

a number o

f

i nput parameters

and determine whethe

r a change

in the

i nput parameter

would m ake any difference

to the model results

(or the conclusions

drawn from those mode

l results).

For some

of the parameters evaluated,

a change

in the input value

has

a n eglig ible effect

on the modeled concentrations

. For example, adjusting

the receptor f

l agpole heights
from

0 to 1.5

m has

a very small effect

on the modeled

S0

2 

# concentrations.

S imil
ar

l y, the use

of variable
stack temperature

and veloci

ty also had

a negl

igi

b le impact

on the results. Some

of NRG's inputs

, however

, were found

to have

a more significant

effect

on the model results.

For example

, using

a stack diameter

that

is too large

( 7

. 315

m rather t han 6.7
m) was

s h own

to underpredict

the Unit

7 stack's contribution

to the modeled des

i gn value

by abo

ut 10 percent. NRG's modeled design value

for the total Parish facility

wil

l therefore

be underpredicted

by about

3 percent

due

to the

l arger Unit

7 stack d

i ameter. The select

io
n of the center location

for the computation

of surface characteristics

by the AERSURFACE
processor

has

a far greater effect

on the mode

l results than any

of the other input parameters

tested

. The cho

i ce of the Parish location

, rather than the r ecommended

location (Sugar

Lan

d Airport

), had

a considerable

effect

on the estimated surface character

i stics, especia

l ly the weighted average surface roughness heights.

It was found
that using

the Parish

lo cat

i on as the center point resu

l ted

in mixing heights that
we

r e much

too high, which resulted

in

a significant underprediction

of modeled

S0

2 

# concentrations.

· T he NRG modeled design value

S0

2 

# concentration

for Paris

h U nits

5

- 8 was 163

. 2 j.Jg/m

3

.



# I f the Sugar Land Airport location

had been used

as

t he center point during

the developme

n

t of the surface characterist

i cs

, as recommended

i n the AERSURFACE guidelines,

t he modeled design value

for Units
5-8 would

be approximately

31 percent h

i gher. Indeed

, the use

of the surface characteristics recommended

by EPA guide

l ines results

in

a modeled design value

of approximately

214.5 lJg/m

3

, 

# suggesting

that

a nonatta

i nment designation

for Parish

is appropriate.

In addition

, if the Unit

7 stack was modeled

wi

t h the correct diameter

(6.7

m rather than 7.315

m)

, then the modeled des

i gn va lue for the Par

i sh facility would increase

by anothe

r 3 percent. Making these tw

o changes

in the inputs

to the model would result

in

a greater
than

35 percent increase

i n

t he modeled design

va

l ue concentration.

I t is es

t imated

t hat the modeled design

val

u e concentration

for Parish Units
5-8 (not including background)

would i ncrease

to 221 lJg/m

3

, 

# which would exceed

the allowable 1-hour

S0

2 NAAQS

level ( 196.2 lJglm\

8NRG

' s model resul

t s (design

va

l u e= 168.6

1Jg

/ m

3

,

t o tal
fa

c ility, including
backg

r oun

d

) sugg

e st that the Parish facility would

not cause

a violation

of the 1-hour

S0

2 NAAQS

. As demonstrated

in this ana

l ysis, however,

using
the appropriate

stack diameter

for

U nit 7 an

d th
e recommen

d e d center location (Sugar Land Airport) during

the developme

n
t of the

s u rface characte

r istics would increase

the modeled design value well beyond

the acceptable

N AAQS level. Making these changes would

a

l so therefore change

t he con clu sion regarding

the source

' s complian

c e with the NAAQS.

It should

be conclu

d ed tha

t e m issions
from

t h e Parish

sou

r ce

, on the

i r own

, will

l

i k ely cause

a violation

of

t h e

1

- hour S02 NAAQS

.

9