## APPENDIX C

Interstate Transport Analysis for the 20 10 Sulfur Dioxide

Primary National Ambient Air Quality Standard

## (This page left intentionally blank.)C

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## APPENDIX C

Interstate Transport Analysis for the 20 10 Sulfur Dioxide Primary National Ambient Air Quality Standard

C .1 INTRODUCTION

Section 110(a)(2)(D)(i )(I) of the Clean Air Act (CAA) requires each state to prohibit emissions that contribute significantly to nonattainment in, or interfere with maintenance by, any other state with respect to any primary or secondary national ambient air quality standard (N AAQS). The Nevada Division of Environmental Protection (NDEP) evaluated the impact of transport of sulfur dioxide ( SO 2 ) emissions from Nevada sources to sensitive receptor areas in nearby states, other

western states and eastern states. The NDEP used the U

. S

. E nvironmental P rotection A gency (US EPA ) map of preliminary nonattainment areas for the 2012 SO 2 NAAQS ( http://www. epa .gov/airquality/sulfurdioxide/designations/pre limmap.html ) and the US EPA 2011 Design Value Report for Sulfur Dioxide ( http://www. epa .gov/airtrends/values.html ) to identify receptor area s
, i.e., air quality planning areas that are nonattainment or maintenance for the 2010 or previous SO 2 NAA Q S or areas that ha ve monitored values approaching the NAAQS

.

In evaluating the possible impact of SO 2 transport from Nevada sources , the NDEP reviewed

other states ’ state implementation plan (SIP) s ubmittals, 2010 SO 2 NAAQS designation requests and responses and associated technical support documents, wi n d rose plots, 2008 National Emissions Inventory (NEI) data, and Clean Air Status and Trends Network (CASTNET

, http:// epa .gov/castnet/javaweb/index.html ) monitoring data. CAS T NET sites are located in areas

where urban influences are minimal ; they are considered representative of regional background

SO 2 levels. The NDEP reviewed five years (2007

- 2012) of CASTNET data collected at six national parks and one national monument : Nevada (Great Basin National Park), Utah (Canyonlands National Park), Montana (Glacier National Park), Colo rado (Mesa Verde National Park), and Arizona (Grand Canyon National Park, Petrified Forest National Park, Chiricahua National Monument) ( http://java. epa .gov/castnet/clearsession.do )

. The SO 2 data for each of the

seven CAS T NET monitoring sites examined show low background SO 2 levels throughout the

year. Both a verage w eekly and seasonal SO 2 concentrations from the CAS T NET sites were low

, below 2 ppb

, indicating that the regional SO 2 background concentrations are relatively low, which in turn implies that the bulk of the SO 2 in the urban receptor areas is locally generated and not a regional or transport phenomenon

.

C .2 TRANSPORT TO NONATTAINMENT RECEPTORS IN NEARBY STATES

The NDEP identified nonattainment receptors in two adjacent states: Arizona and Utah.

C .2.1 Arizona

The nearest nonattainment receptors to Nevada are the Hayden and Miami SO 2 planning areas located in portions of Gila and Pinal Counties, Arizona. US EPA indicated in its February 6, 2013

120

- day letter to the Governor of Arizona that it intends to designate Hayden and Miami

nonattainment for the 2010 SO 2 standard , in accordance with the Governor’s recommendation

. InC

- 2

t he 2002 Hayden SO 2 Nonattainment Area State Implementati on and Maintenan ce Plan Arizona

states

, “ Emissions inventories from all sources in the Hayden nonattainment area indicate that although ther e are other sources of SO 2 emissions, the ASARCO sm elter is the primary source

for SO 2 emissions and comprises mo re than 99 percent of total SO 2 emissions in the area. ” ( http://www.azdeq.gov/environ/air/plan/download/haydensip.pdf

, p.27 )

. Similarly

, the 2002

Miami SO 2 Nonattainment Area State Implementation and Maintenance Plan notes , “ Emissions inventories from all sources in the Miami nonattainment area indicate that althoug h there are

other sources of SO 2 emissions, the Miami smelt er is the primary source for SO 2 em issions and comprises more than 99 percent of total SO 2 emissions in the are a. ” ( http://www.azdeq.gov/environ/air/plan/download/miamisip.pdf , p.25)

. The emissions

inventories for Hayden and Miami support the position that the elevated SO 2 levels in Hayden and Miami are predominantly caused by local emission sources and not transport

.

T he Hayden SO 2 p lanning a rea is situated in part o f Gila and Pinal Counties, while the Miami

SO 2 p lanning a rea is located within Gila County. These air quality planning areas are less than 50 kilometers apart. US EPA ’s 2008 N ational E mission I nventory shows emissions from the Gila

and Pinal C ounties total 29,470 tons ( http://www. epa .gov/air/emissions/index.htm )

. T he closest

SO 2 source in Nevada to the Hayden/Miami area is t he Reid Gardner Generating Station (RGGS) in Las Vegas

. RGGS is approximately 330 miles from Hayden and 305 miles away from Miami

and emitted 940.69 tons of SO 2 in 2008 or about three percent of the emissions from the receptor

areas

.

Meteorological data at the McCarran International Airport in Las Vegas for 2003 through 2011 indicate that the prevailing winds in Las Vegas are from the south

- southwest ( Figure C .1) . We can assume that winds leaving the Las Vegas area would blow mainly north

- northeast, and not

toward the Hayden/Miami area , which lies southeast of Las Vegas. W ind data from the Phoenix Sky Harbor International Airport for 2003 through 2011 show that the prevailing winds in

Phoenix come mainly from the east and to a lesser degree from the west ( Figure C

. 2 )

. Thus, it is

reasonable to conc lude that locations southeast of the Phoenix area such as Hayden and Miami

are not significantly influenced by winds from Nevada.

With respect to Arizona, the NDEP find s that emissions from Nevada do not significantly

con tribute to nonattainment of the 2010 SO 2 NAAQS , based on the following evidence : (1) technical information indicating that elevated SO 2 levels in Hayden /Miami were predominantly cause by local emission sources

, (2) insignificant SO 2 emissions from RGGS compared to local

sources, (3) CASTNET data indicating that regional background levels of SO 2 are generally

low

, and (4) meteorological data showing that the prevailing winds do not blow from Nevada toward the Hayden and Miami receptors

.C

- 3 FIGURE C .1

LAS VEGAS, N EVADA WIND ROSE PLOT, 2003

- 2011C

- 4 FIGURE C .2

PHOENIX, ARIZONA WIND ROSE PLOT, 2003

- 2011C

- 5

C .2.1 Utah

Although Salt L ake County and Tooele County, Utah are still designated nonattainment for the

24

- hour and annual 1971 SO 2 standard , there have been no recorded v iolation s of the SO 2 NAAQS since 1981 ( http://www.airquality.utah.gov/Planning/SIP/SIPPDF/Secixb6.pdf ). Utah’ s October 25, 2011 letter to US EPA with area designation recommendations for the 2010 SO 2 NAAQS confirm s Utah’s long history of clean data: “Because Salt Lake County remains a

nonattainment area for the initial 1971 S O 2 NAAQS, Utah h as a long

- standing and robust SO 2 monitoring network in Salt Lake County, extending into neighboring Davis County. For the past 29 years, at none of those monitor ing stations has the ambient SO 2 concentration ever violated

either the initial or revised standard.” ( http://www. epa .gov/so2designations/recletters/R8_UT_rev_rec.pdf ). US EPA ’s 120

- day letter to

Utah regarding responding to the Governor’s letter confirms continued clean data throughout

Utah through 2011 ( http://www. epa .gov/so2designations/ epa resp/08_UT_resp.pd )

. The NDEP concludes that no areas in Utah are in danger of exceeding the 2010 SO 2 NAAQS.

The NDEP concludes that emissions from Nevada do not significantly con tribute to

nonattainment of the 2010 SO 2 NAAQS in Utah , based on the following evidence : (1) monitoring data indicating that elevated SO 2 levels in the Salt Lake

- Tooele Counties

nonattainment area ceased decades ago , and (2) CASTNET data demonstrating that regional background levels of SO 2 are even low er than the low SO 2 levels at identified receptors.

C .3 TRANSPORT TO NONATTAINMENT RECEPTORS IN WESTERN STATES

The NDEP identified two nonattainment rece ptors in one distant western state: Montana.

C .3.1 Billings and Laurel Area, Montana

In its February 6, 2013 120

- day letter

, the US EPA notified the Governor of Montana of its intent to designate Yellowstone County nonattainment for the 2010 SO 2 NAAQS. Within Yellowstone County

, all of the facilities that emit SO 2 are located in the Billings and Laurel areas. Billings and Laurel are 15 miles apart. The re are seven industrial point sources that are significant

emitters of SO 2 in the Billings /Laurel area : three petroleum r efineries; a sugar beet processing plant; a coal

- fired electrical generating station; a sulfur recovery plant ; and a petroleum coke

fired electrical/steam co

- generation facility. Total emissions from these seven sources averaged

about 800 0 tpy during 2008, 2009 and 2010. ( http://www. epa .gov/airquality/sulfurdioxide/designations/recletters/R8_MT_rec.pdf )

The closest SO 2 source in Nevada to the Billings/Laurel receptor area is the North Valmy Generating Station, which is jointly owned by NV Energy and Idaho Power. Valmy is over 540

miles from the receptor area

. In 2008

, Valmy emitted 8130 tons of SO 2

. The NDEP reviewed meteorological data for Reno International Airport from 2003 through 2011 to in di cat e the prevailing wind direction for potential transport to the Montana nonattainment receptor s (Figure

C .3)

. The data indicate that the prevailing winds at Reno are mainly from the west

- northwest

. We can assume winds leaving the Reno area would blow east or southeast

, not toward the

Montana SO 2 nonattainment receptor s which lie northeast of Reno and Valmy

.C

- 6 FIGURE C .3

RENO, N EVADA WIND ROSE PLOT, 2003

- 2011

Nevada relies on t he following evidence to support a finding that emissions from Nevada do not significantly con tribute to nonattainment of the 2010 SO 2 NAAQS at the Billings/Laurel receptor

area : ( 1 ) the overwhelming contribution of seven significant local emission sources to high SO 2C

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levels in the Billings/Laurel area, ( 2 ) CASTNET dat a indicating that regional background levels

of SO 2 are generally low during the time periods of elevated SO 2 at the receptors

, ( 3 ) the significant distance from the state of Nevada to the nonattainm ent receptors in Montana

, and (4) the prevailing winds at Nevada emission sources not blowing toward the receptor area.

C .3.2 East Helena
, Montana

In 1978, East Helena (in Lewis and Clark County) , Montana was designated nonattainment for

the 1971 SO 2 standard

. In 1995

, US EPA approved Montana’s SO 2 attainment demonstration SIP

for East Helena

. The SIP was developed in consultation with the ASARCO primary lead smelter

, the only significant source of SO 2 emissions in the East Helena nonattainment area ( 60 FR 5313, January 27, 1995)

. The ASARCO smelter shut down in 2001

. According to the 2008 NEI, Lewis and Clark County emitted only 28 tons of SO 2 from all source sectors combined in 2008 ( http://www. epa .gov/air/emissions/index.htm )

. US EPA has not proposed to designate East

Helena nonattainment for the 2010 SO 2 standard.

Nevada’s closest significant source to the receptor area is the North Valmy Generation Station,

which is approximately 4 80 miles away . Valmy emitted 8130 tons of SO 2 in 2008

. The NDEP reviewed meteorological data for Reno International Airport from 2003 through 2011 as a general indication of the prevailing wind direction for potential transport to the East Helena

receptor (Figure C .3). The data indicate that the prevailing winds at Reno are mainly from the

west

- northwest . We can assume winds leaving the Reno area would blow east or southeast, not

toward East Helena, which is northeast of Reno and Valmy

.

Nevada relies on t h e following evidence to support a finding that emissions from Nevada do not significantly con tribute to nonattainment or maintenance of the SO 2 NAAQS in East Helena : ( 1 ) information indicating that SO 2 levels were predominantly c aused by a local emission sourc e that has since been shut down, ( 2 ) CASTNET dat a indicating that regional background levels of SO 2

are even low er than concentration s currently monitored in Helena

, Montana

, ( 3) the significant

distance from the state of Nevada to the nonattainm ent receptor in Montana

, and (4) the prevailing winds at Nevada emission sources not blowing toward the receptor area

.

C .4 TRANSPORT TO MAINTENANCE RECEPTORS IN NEARBY STATES

The NDEP identified maintenance receptors in one adjacent state: Arizona.

C .4.1 Arizona

There are four maintenance areas for the 1971 SO 2 NAAQS in Arizona: the Ajo, Douglas

, Morenci, and San Manu e l SO 2 planning areas. In 2001

- 2002, Arizona submitted redesignation requests and maintenance plans for all four areas. The emission invento ries in those plans show that nearly all of the SO 2 emissions in those areas came from the various copper smelters located

the s e maintenance areas ( http://www.azdeq.gov/environ/air/plan/ )

. Only one smelter remains operational and is located in the San Manu e l SO 2 planning area. There have been no recorded monitoring violations of the SO 2 NAAQS in any of these areas since the mid

- 1980s.

Furthermore , US EPA has not proposed to designate San Man uel nonattainment for the 2010 SO 2 standard.C

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The RGGS in Las Vegas is the closest SO 2 source in Nevada to the receptor areas . RGGS is approximately 300 miles from Arizona’s nearest maintenance receptor. Meteorological data at the McCarran International Airport in Las Vegas for 2003 through 2011 indicate that the prevailing winds in Las Vegas are from the south

- southwest (Figure C .1). We can assume that winds leaving the Las Vegas area would blow mainly no rth

- northeast, and not toward the

maintenance areas , which lie south

- southeast of Las Vegas. Meteorological data from the Phoenix Sky Harbor International Airport for 2003 through 2011 show that the prevailing winds

in Phoenix come mainly from the east and to a lesser degree from the west (Figure C .2)

. Thus, it

is reasonable to conclude that the maintenance areas southeast of the Phoenix area are not significantly influenced by emissions from Nevada.

Based on the following evidence, the NDEP concludes that emissions f rom Nevada do not significantly interfere with the maintenance o f the SO 2 NAAQS in Ajo, Dougl as , Morenci, or

San Manu e l : (1) technical information indicating that elevated SO 2 levels in the m aintenance

areas were predominantly cause d by local emission sources

, (2 ) CASTNET data indicating that regional background levels of SO 2 are generally low

, (3) the significant distance from the state of Nevada to the receptor s
, and ( 4 ) meteorological data showing that the prevailing winds do not blow from Nevada toward the maintenance receptors

.

C .5 TRANSPORT TO MAINTENANCE RECEPTORS IN WESTERN STATES

The NDEP identified maintenance receptors in one distant western state: New Mexico.

C .5.1 New Mexico

Grant County, New Mexico was designated nonattainment in 1978 and redesignated attainment

in 2003. There have been no monitored violations of the SO 2 NAAQS since 1975. New Mexico

attributes past violations to the H urley smelter located directly outside the town of Hurley ( http://www.nmenv.state.nm.us/aqb/Control_Strat/sip/Grant_Text.pdf )

. As a consequence of

emission controls place d on the smelter, Grant County had only 18 tons of SO 2 emissions in

2008 ( http://www. epa .gov/air/emissions/index.htm )

. US EPA has not proposed to designate Grant County nonattainment for the 2010 SO 2 standard ( http://www. epa .gov/so2designations/ epa resp/06_NM_resp.pdf )

.

The RGGS in Las Vegas is the closest SO 2 source in Nevada to the Grant County maintenance area, approximately 570 miles awa y. RGGS emitted 940.69 tons of SO 2 in 2008. Meteorological data at the McCarran International Airport in Las Vegas indicate that the prevailing winds in Las Vegas are from the south

- southwest (Figure C .1). We can assume that winds leaving the Las Vegas area would blow mainly north

- northeast and not southeasterly toward Grant County.

Absent CASTNET data for New Mexico, t he NDEP reviewed five years (2007

- 2012) of data

from four national parks between Ne vada and New Mexico to determine SO 2 background in New Mexico. These sites include the Mesa Verde National Park in Colorado, and the Grand Canyon National Park, Petrified Forest National Park

, and Chiricahu a National Monument in Arizona

. Both average weekl y and seasonal SO 2 concentrations from these National Park Service sites were low, below 2 ppb, indicating that the regional SO 2 background concentrations are relativelyC

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low, which in turn implies that the bulk of the SO 2 in the urban receptor areas is locally generated and not a regional or transport phenomenon.

Nevada relies on the following evidence to support a finding that emissions from Nevada do not significantly interfere with the maintenance of the 2010 SO 2 NAAQ S in Grant County, New

Mexico : (1 ) technical information indicating that elevated SO 2 levels in m aintenance area were predominantly cause d by the Hurley smelter, (2) the significant distance from the state of Nevada to the receptor area, and ( 3 ) representative air quality data indicating that regional background levels of SO 2 are generall y low

.

C .6 TRANSPORT TO NONATTAINMENT/MAINTENANCE RECEPTORS IN

EASTERN STATES

The NDEP also considered potential SO 2 transport from Nevada emission sources to the nearest nonattainment or maintenance receptor s located in the eastern, m idwestern, and southern states

. The nonattainment receptor nearest to Nevada is Jackson County, Missouri

. The US EPA has proposed to desig nate Jackson County, Missouri nonattainment for the 2010 SO 2 NAAQS ( http://www. epa .gov/airquality/sulfurdioxide/designations/ epa resp/07_MO_resp.pdf ). Jackson

C ounty is over 1000 miles away from the border of Nevada.

The NDEP evaluated the relative magnitude of SO 2 emissions in Nevada to SO 2 emissions in

Missouri. The 2008 NEI indicates that SO 2 emissions in Nevada are less than 5 percent of the

SO 2 emissions in Missouri ( http://www. epa .gov/air/emissions/index.htm )

. Specifically, the 2008

NEI shows 16,813 tons of SO 2 from Nevada sources

, compared to 415,204 tons of SO 2 from

Missouri sources ( 34,693 tons SO 2 in Jackson County)

.

T he NDEP believes the following factors support a finding that emissions from Nevada do not significantly con tribute to nonattainment of the 2010 SO 2 NAAQS at the Jackson County receptor: (1 ) the relatively small magnitude of the emissions inventory of SO 2 in Nevada compared to Missouri , combined with (2) the relatively long distance of the state of Nev ada from the receptor. T hese factors also support a qualitative conclusion that emissions from Nevada sources do not significantly contribute to nonattainment or interfere with the maintenance of these NAAQS at any of the other receptors farther east.

C .7 CONCLUSION

The preceding analysis indicates that sulfur dioxide nonattai nment (current, and impending for the 2010 NAAQS) and maintenance areas in adjacent and nearby states, as well as other western and eastern states are generally the result of documented local emission sources, which in some cases have ceased operation sinc e the time of designation. Furthermore, the receptor areas the

NDEP identified for the 2010 SO 2 NAA Q S are a considerable distance from Nevada sources.

Based on these factors and the above evaluation, the State of Nevada concludes that sulfur

dioxide emissions from Nevada do not contribute to nonattainment or interfere with maintenance

of the 2010 SO 2 standard or the previous S O 2 standards in any other state. Nevada commits to continue to review new air quality information as it becomes available to e nsure that this negative declaration is still supported by such information.