1 ----------------------------------------------------------------------------------------------------------------------------- - Draft Technical Support Document (TSD)

Iowa Area Designations For the 2010 SO 2 Primary National Ambient Air Quality Standard

Summary

Pursuant to section 107(d) of the Clean Air Act (CAA), EPA must initially designate areas as either “unclassifiable”, “attainment”, or “nonattainment” for the 2010 1

- hour sulfur dioxide (SO 2 ) primary national ambient air quality standard (NAAQS). The CAA defines a nonattainment area as one that does not meet the NAAQS or that contributes to poor air quality in a nearby area that does not meet the NAAQS. Table 1 below identifies the counties or portions of counties (or Indian Country ) in Iowa that EPA intends to initially designate “nonattainment” based on monitored violations

.

Table 1. Nonattainment Area De signations for Iowa

County Name Iowa Recommended Designation of Areas/Counties EPA’s Intended Designation of Areas/Counties

Muscatine Unclassifiable Nonattainment

Background

On June 2, 2010, EPA revised the primary SO 2 NAAQS (75 FR 35520, June 22, 2010) by establishing a new 1

- hour standard at a level of 75 parts per billion (ppb) which is attained when the 3

- year average of the 99 th percentile of the daily maximum 1

- hour average concentration at each monitor in an area does not exceed 75 ppb

. EPA has determined that this is the level necessary to provide protection of public heal th with an adequate margin of safety, especially for children, the elderly and those with asthma. These groups are particularly s usceptible to the health effects associated with breathing SO 2
. The Agency is revoking the two prior primary standards of 140 ppb evaluated over 24

- hours, and 30 ppb evaluated over an entire year because the standards will not add additional public health protection given a 1

- hour standard at 75 ppb. Accordingly, EPA is not designating areas in this process on the basis of eith er of these two prior primary standards. Similarly, the secondary standard for SO 2 has not been revised, so EPA is not designating areas in this process on the basis of the secondary standard

.

EPA ’s SO 2 Designation Approach

Section 107(d) of the CAA requires that not later than 1 year after promulgation of a new or revised NAAQS, state Governors must submit their recommendations for designations and boundaries to EPA. This deadline was in June, 2011. Section 107(d) also req uires EPA to provide a notification to states of no less than 120

- days prior to promulgat ing an initial area designation that is a modification of a state’s recommendation. EPA has reviewed the State’s recommendations and has notified the S tate2 Commissio ner through letter signed by the Regional Administrator of any intended modifications. If a State or Indian Country did not submit designation recommendations, EPA will promulgate the designations that it deems appropriate. If a state or Indian Country disagrees with EPA’s intended area designations, they have an opportunity to demonstrate why any proposed modification is inappropriate.

Designations guidance was issued by EPA through a March 24, 2011, memorandum from Stephen D. Page, Director, U.S. EPA, Office of Air Quality Planning and Standards, to Air Division Directors, U.S. EPA Regions I

- X. This memorandum identifies factors EPA intends to evaluate in determining boundaries for areas designated nonattainment. These 5 factors include: 1) Air quality data; 2) Emissions and emissions

- related data (location of sources and potential contribution to ambient SO 2 concentrations) ; 3) Meteorology (weather/transport patterns); 4) Geography/topography (mountain ranges or other air basin boundaries); and 5) Jurisdictional boundaries (e.g., counties, air districts, pre

existing nonattainment areas, reservations, metropolitan planning organization), among any other information deemed relevant to establishing appropriate area designations and boundaries for t he 1

- hour SO 2 NAAQS

. The March 24, 2011, memo recommended that area boundaries be defaulted to the county boundary unless additional provided information justifies a larger or smaller boundary than that of the county. EPA believes it is appropriate to evaluate each potential area on a case

- by

- case basis, and to recognize that area

- specific analyses conducted by states, Indian Country a nd/or EPA may support a differ ent boundary than a default county boundary.

In this TSD, EPA discusses its review and technical analysis of the recommendations submitted by the states and/or Indian Country for designations of the 1

- hour SO 2 standard and an y modifications from these recommendations.

Definition of important terms used in this document:

1) Designated “nonattainment” area

– an area which EPA has determined, based on a s tate recommendation and/or on the technical analysis included in this document, has violated the 2010 SO 2 NAAQS

, or contributes to a violation in a nearby area.

2 ) Recommended nonattainment area

– an area a State or Indian Country has recommended to EPA be designated as nonattainment.

3 ) Violating monitor

– an ambient ai r monitor meeting all methods, quality assurance and citing criteria and requirements whose valid design value exceeds 75 ppb, as described in Appendix T of 40 CFR part 50.

4 ) 2010 SO 2 NAAQS

- 75 ppb, n ational a mbient a ir q uality s tandard for SO 2 promulgated in 2010. Based on the 3

- year average of the 99 th percentile of the annual distribution of daily maximum 1

- hour average concentrations

5 ) Design Value

– a statistic that describes the air quality status of a given area relative to the level of the NAAQS

.3 Nonattainment Designations

Introduction

In Iowa’s designation recommendation letter to EPA, dated June 2, 2011, Terry E. Branstad, Governor of Iowa, recommended that 5 counties be designated as attainment for the 2010 SO 2 NAAQS based on monitored air quality data from 2008

- 2010 , with all other counties designated as unclassifiable

. Based on EPA’s technical analysis, EPA is intending to designat e 1 county in the State of Iowa as nonattainment (Table 1).

The 5 factors were used to ana lyze the nonattainment area for 1

- hour SO 2 designations :

1. Air quality data. We reviewed SO 2 air quality monitoring data from EPA’s Air Trends website (see http://www.epa.gov/airtrends/values.html ), including the design value calculated for the monitor in Muscatine County, Iowa for the years 2008

- 2010

. A monitor’s design value indicates whether that monitor attains a specified air quality standard. The 20 10 SO 2 NAAQS is met at a monitoring site when the identified design value is valid and less than or equal to 75 ppb as described in Appendix T of 40 CFR P art 50 ; however, data from the Musser Park monitor in Muscatine, IA could no t be validated using the standard procedure found in Appen dix T be cause a substantial amount of data had been flagged from the years 2008, 2009 and 2010.

The data was flagged as a result of a malfunction of the internal calibration system of the monitor . The malfunction wasn’t detected immediately and the monitor con tinued to collect data for over a year

. The malfunction was discovered following performance of a reference procedure on the monitor ’ s SO 2 calibration system . Following the reference procedure a reference audit was completed which informed IDNR and EPA th at the monitor had been operating out of specification. Following the audit, EPA and IDNR reviewed the results and jointly agreed to : 1) adjust the original recorded values to account for the calibration error; 2) certify the adjusted values into the Air Quality System (AQS) database; and, 3) flag the adjusted data in the AQS database so it could not be used for regulatory purposes.

Due to the large amount of flagged data the Musser Park monitor no longer met the minimum data completeness criteria for the period of time which we are using to evaluate compliance with the NAAQS

. The com pleteness criteria specifie d in Appendix T of 40 CFR Part 50 requires 3 years of complete data to establish a design value . A year is complete when all 4 quarters ar e complete. A quarter is complete when 75% of the days are complete. A day is complete when it has 75% of its hours. Although Appendix T of 40 CFR Part 50 includes data substitution provisions , due to the large amount of missing data from the Musser Par k monitor

, the data substitution provisions were not applicable

. However, 40 CFR Part 50 Appendix T 3(d) allows the Administrator of EPA to consider other factors, such as consistency and levels of the valid concentration measurements that are available for the purpose of establishing a design value.

The Appendix T 3(d) provision was applied in the Musser Park situation because the valid data recorded from the monitor for the number of years preceding and following the malfunction included sufficient h igh hourly measurements to demonstrate the ambient SO 2 concentration in Muscatine, IA was significantly above the new health

- based standard of the 2010 SO 2 1

- hr4 primary NAAQS. In fact, in evaluating whether to apply the Appendix T 3(d) provision to the Musser Park data, EPA Region 7 took the most conservative approach possible and assumed that all the data that was flagged between the dates of August 30, 2008 to September 20, 2010 was zero (i.e., the monitor reported a zero 1

- hr concentr ation of SO 2 in the ambient air for the period of malfunction ) . This approach resulted in a design value 123ppb, which exceeds the NAAQS by 150% , and demonstrates that the monitor is recording a violation of the 1

- hr standard.

2. Emissions and emissions

- related data We reviewed data from the 2008 National Emissions Inventory (NEI), version 2 (NEI 20 08V 2 .0 ), which was the most current version of the national inventory available in 20 11 when these data were compiled for the designations process

, (s ee http://www.epa.gov/ttn/chief/net/2008inventory.html )

. EPA recognize s that there might be new information associated with any changes in emissions that may have occurred after 2008, and

w ill consider more recent years if available . For example, certain large sources of emissions in

or near an area may have installed emission controls or otherwise significantly reduced emissions since 2008

. Two source categories from the 2008 NEI were examin ed: the point source inventory and the nonpoint source inventory. Generally, the point source inventory represents the bulk of the SO 2 emissions in Region 7.

3. Meteorology We evaluated meteorological data to help determine how weather conditions, includi ng wind speed and direction, affect the plume of sources contributing to ambient SO 2 concentrations. The National Weather Service maintains surface and upper air monitoring sites across the United States. Automated Surface Observing System (ASOS) ( http://www.weather.gov/asos ) sites collect hourly averaged wind measurements including wind direction and wind speed.

4. Geography/topography We examined the physical features of the land that might affect the distribution of SO 2 over an area. River valleys

, e scarpments, or other physical features may affect the distribution of emissions, and may help define boundaries. Satellite images depicting

r iver v alleys and point sources were constructed and evaluated to determine the effects of the topography on point source emissions.

5. Jurisdictional Once the geographic area associated with the area violating the SO 2 standard a nd the nearby area contributing to violations were determined, we considered existing jurisdictional boundaries for the purposes of providing a clearly defined legal boundary for carrying out the air quality planning and enforcement functions for the nonat tainment area. If an existing jurisdictional boundary is used to help define the nonattainment area, it encompasses all of the area that has been identified as meeting the nonattainment definition. These existing boundaries may include an existing nonatt ainment or maintenance area boundary, a county or township boundary, a metropolitan area boundary, an air management district, or an urban planning boundary established for coordinating business development or transportation activities. Where existing jur isdictional boundaries are not adequate to describe the nonattainment area, other clearly defined and permanent landmarks or geographic coordinates are used.5 Nonattainment Designations T e chnical analysis for Muscatine County, Iowa

Introduction

Thi s technical analysis for Muscatine County, Iowa identifies the entire county with a monitor (AQS ID 191390020) that violates the 2010 SO 2 NAAQS based on 2008

- 2010 data, and evaluates nearby counties for contributions to SO 2 concentrations in the area. EPA has evaluated this county and nearby counties based on the weight of evidence of the factors recommended in the March 24, 2011, issued EPA guidance.

Figure 1 is a map of the area in IA that EPA intends to designate nonat tainment for the 2010 1

- hr SO 2 NAAQS including source information and the location of the monitor violating the standard.

Figure 1. Muscatine County, IA Intended Nonattainment Boundary6 Figure 2 is a map of the area analyzed showing the location of the air quality monitor s in the area, the Muscatine County line in red, and large sources of SO 2 in the greater Muscatine Co. area

.

Figure 2 : Muscatine County Showing SO 2 Monitor and Sources of SO 2

On June 2, 2011 Governor of Iowa, Terry E. Branstad, recommended that 5 counties in Iowa with SO 2 monitors reporting ambient concentrations below the 75ppb standard be designated attainment and all other areas of the state be designated unclassifiable for the 2010 SO 2 NAAQS b ased on monitored air quality data from 2008

- 2010

. The state provided no further information or analysis supporting their attainment recommendations other than the monitored values for the years 2008 through 2010.

EPA, based on its t echnical analysis described below, is intending to designate one county in Iowa as nonattainment and to defer classifications for all other counties until a later date

. EPA is proposing to designate all of Muscatine County, Iowa as nonattainment

, based upon curren tly available information

, and the application of 40 CFR Part 50 Appendix T 3(d)

. The county listed for nonattainment is listed above in Table 1

.7 Detailed Assessment

Air Q uality D ata

This factor considers the SO 2 air quality monitoring data, including the design values (in ppb ) calculated for all air quality monitors in Muscatine County and the surrounding area based on data for the 2008

- 2010 period.

EPA Region 7’s proposal is based on data from (a) Federal Refe rence Method (FRM) or Federal Equivalent Method (FEM) monitor(s) located in the state.

The 2011 SO 2 NAAQS design values for all counties (containing a monitor) in the State of Iowa and surrounding area are shown in Table 2

.

Table 2 . Air Quality Data for All Monitors in the State of Iowa

County State Recommended Nonattainment? Monitor Name Monitor Air Quality System ID Monitor Location SO 2 Design Value, 2008

- 2010 (ppb)

Muscatine No Musser Park 191390020 Muscatine, IA 1 23*

Clinton No Chancy Park 190450019 Clinton 30

Linn No Scottish Rite Temple 191130031 Cedar Rapids 38

Polk No Public Health Building 191530030 Des Moines 3

Scott No Jefferson School 191630015 Davenport 10

Van Buren No Lake Sugema 191770006 Keosuaqua 5

* The DV is based on an application of the 40 CFR Part 50 Appendix T 3(d) providing authority for the Administrator to approve the use of an incomplete data set to establish a valid DV.

The Musser Park monitor in Muscatine, IA shows a violation of the 2010 SO 2 NAAQS

. Therefore

, EPA must determine the appropriate boundaries for the area surrounding the violating monitor to be designated nonattainment, otherwise by default EPA identifies the entire county as the area of nonattainment

. The absence of a v iolating monitor alone is not a sufficient reason to eliminate nearby counties as candidates for inclusion in a nonattainment area as well . E ach area has been evaluated based on the weight of evidence of the five factors and other relevant information.

Emissions and Emissions

- Related Data

Evidence of SO 2 emissions sources in the vicinity of a violating monitor is an important factor for determining whether a nearby area is contributing to a monitored violation. For this factor, EPA evaluated county level emission s data for SO 2 and any growth in SO 2 emitting activities since the date represented by those emissions data

.8 Emissions

EPA recognizes that there may be important new information on emissions levels for the period after 2008, and would co nsider more recent information if available

. EPA relied on verified emissions data currently available in the 2008 N ational E missions I nventory (NEI) emissions data base ( NEI 20 08V2 .0 )

.

Table 3 shows total emissions of SO 2 (given in tons per year) for violating and potentially contributing counties in and around the Muscatine County, Iowa including s ources emitting greater than 100 ton s per year of SO 2 according to the 2008 NEI

. The two IA count ies adjacent to Muscatine, Co with source s within 50 kilometers and emitting greater than 100 tons per year are found in Louisa County, IA , and Scott County, IA . The source in Louisa County is an electric generating unit owne d and operated by MidAmerican Ene rgy (the Louisa Power Station). The other source of SO 2 (2,488 tons per year

- not listed in the table 3 below) located outside of Muscatine Co. is Lafarge North America Cement Kiln in Buffalo, IA (Scott County) approximately 31.5 kilometers East

- Northeast of the violating monitor. Based on the distance of the se source s from the violating monitor, and the predominant wind patterns in the area at times violations are recorded at the monitor , th ese source s will not impact the monitor to cause a violation.

Table 3

. Annual SO 2 Emission s 2008
County Facilit y >80 tpy (EIS or State Facility ID) Facility Emissions (tpy) Total County SO 2 Emissions (tons per year)

Muscatine Grain Processing Corporation 14, 979

Central Iowa Power

– Fair Station 7,068

Muscatine Power and Water 3,458 Monsanto Company 520

SSAB Iowa Inc 374 Gerdau Ameristeel US 80 26, 479 Louisa Mid American

– Louisa Station 2,453 2,453

Scott La Farge North American 2,488 2,488 Area Total 31,420

Emissions Controls

The emissions data used by EPA in this technical analysis and provided in Table 3 represent emiss ions levels taking into account any control strategies implemente d on stationary sources in Muscatine and Louisa County up to and including the year 2008 . EPA has not received any additional information on emissions reductions resulting from federally enforceable controls put into place after 200 8

. Emission control information for the sources identified in Table 3 is summarized below.

Grain Processing Corpora tion (GPC) GPC processes grain for the production of food and liquor grade ethanol, as well as a variety of grain based food products and animal feeds. GPC is located 1.2 kilometers South

- Southeast of the violating monitor. As part of the grain conversion and production process GPC operates a variety of boilers for heating and power production. GPC’s main source of SO 2 emissions is emission point #1 (EP

- 1) which9 includes boilers 1, 2, 3, 4, 6 and 7. The boilers range in heat input capacity from 105

– 230 MMBtu/hr. The boilers are capable of burning coal and natural gas. EP

- 1 is limited to 3915 lb s of SO 2 /hr (averaged over a 24

- hour period) and 6 lb/MMBtu. EP

- 1 is not equipped with any SO 2 control system. EP

- 1 is equipped with an SO 2 continuous emissio n monitor (CEM). GPC operates four germ dryers. The germ dryers have the following SO 2 emission limits: 13.73 lb/hr (EP

- 15), 9.20 lb/hr (EP

- 97), 0.53 lb/hr (EP

126) and 500 ppm (EP

- 178). The germ dryers are not equipped with any SO 2 control systems. E P

- 600 is capable of burning biogas and natural gas. EP

- 600 is limited to 4.86 lb SO 2 /hr. EP

- 600 is equipped with a wet gas scrubber. GPC operates gluten flash dryer #4 (EP

- 173) which is capable of burning biogas. EP

- 173 has a heat input capacity of 29 MMBtu/hr. EP

- 173 is limited to no more than 4.5 lb SO 2 /hr. The dryer is equipped with a wet scrubber that is expected to achieve a 91.2% control efficiency while burning biogas. GPC operates four natural gas

- fired “Power House Boilers” (EP

- 103, 104, 142 and 153) with heat input capacities that range from 120

– 124 MMBtu/hr. These boilers burn natural gas only and have an emission limit of 500 ppm. These units are not equipped with any SO 2 control system. GPC operates an additional “Power House Boiler” (EP

- 177) with a heat input capacity of 360 MMBtu/hr. This unit is limited to 500 ppm and 0.23 lb SO 2 /hr. This unit is also not equipped with any SO 2 control system. GPC operates several small natural

- gas fired emission units including dryers. These units are limited to 500 ppm SO 2 and are not equipped with any SO 2 control system.

Central Iowa Power Coop

– Fair Station (CIPC) Central Iowa Power Coop (Fair Station) is an electric generating facility that is located 25.4 kilometers East

- Northeast of th e violating monitor. CIPC’s main SO 2 emission sources are EP

- 1 and EP

- 2. EP

- 1 is a 280 MMBtu/hr boiler that is capable of burning coal and natural gas. EP

- 1 is limited to 6 lb SO 2 /MMBtu. EP

- 1 is not equipped with any SO 2 control system. EP

- 1 is not eq uipped with a SO 2 CEM. EP

- 2 is a 477 MMBtu/hr boiler that is capable of burning coal and natural gas. EP

- 2 is limited to 6 lb SO 2 /MMBtu. EP

- 2 is not equipped with any SO 2 control system. EP

- 2 is equipped with a SO 2 CEM. CIPC also operates a small natu ral gas/diesel boiler and two small emergency generators.

Muscatine Power & Water (MPW) MPW is a nonprofit public utility offering electric, water, and communications services to the greater Muscatine municipal area located 1.9 km South

- Southeast of the v iolating monitor

. MPW’s main SO 2 emission sources are electric generating units designated EP

- 70, EP

- 80 and EP

- 90. EP

- 70 is a 289 MMBtu/hr boiler that is capable of burning coal and natural gas. EP

- 70 is limited to 6 lb SO 2 /MMBtu. EP

- 70 and EP

- 80 are a lso limited to a combined 2,772 lb SO 2 /hr (averaged over a 24

- hour calendar day) and 12,141 tons SO 2 /yr. EP

- 70 is not equipped with any SO 2 control system. EP

- 70 is equipped with a SO 2 CEM. EP

- 80 is a 890 MMBtu/hr boiler that is capable of burning coal, natural gas, waste solvent (limited), diesel oil (limited) and waste oil (limited). EP

- 80 is limited to 6 lb SO 2 /MMBtu. EP

- 70 and EP

- 80 are also limited to a combined 2,772 lb SO 2 /hr (averaged over a 24

- hour calendar day) and 12,141 tons SO 2 /yr. EP

- 80 is not equipped with any SO 2 control system. EP

- 80 is equipped with a SO 2 CEM. EP

- 90 is a 1,556 MMBtu/hr boiler that is capable of burning coal and natural gas. EP

- 90 is limited to 0.56 lb SO 2 /MMBtu (averaged over a 24

- hr calendar day) and 0.45 lb SO 2 /M MBtu (averaged over a 30

- day period). EP

- 90 is also subject to a 92% reduction in SO 2 from the flue gas desulfurization system (scrubbers CE

- 93 and CE

- 94). EP

- 90 is also subject to NSPS Da emission limits. As mentioned, EP

- 90 is equipped with two scrubb ers (CE

- 93 and CE

- 94) that control SO 2 emissions. EP

90 is equipped with a SO 2 CEM. MPW also operates several small diesel and gasoline

- powered emission units.10 La Farge

– North American Lafarge's cement manufacturing plant located in Buffalo, IA main source of SO 2 emissions is the preheater/precalciner/kiln/raw mill system (EP 0466

- 0) located approximately 31 kilometers E ast of the violating monitor in Muscatine, IA The cement processing plant has a capacity of 145.3 tons clinker per hour. EP 0466

- 0 is limited to 4,850 tons SO 2 /yr and 2,900 lb SO 2 /hr. EP 0466

- 0 is equipped with a dry absorbent addition system. EP 0466

- 0 is also equipped with an SO 2 continuous emission monitor. Lafarge can burn a range of approved materials in the kiln.

Lafarge als o has a couple of small fossil

- fired emission units including a diesel

- fired emergency generator and a diesel

- fired water pump that are limited to 2.5 lb SO 2 /MMBtu limit and are not equipped with no controls.

MidAmerican Energy Company

– Louisa Generating Station (MidAmerican) MidAmerican Energy Company is a for profit power production company that operates an electric generating facility in Louisa County, IA 13.9 kilometers South

- Southwest of the violating monitor

, located in Muscatine County, IA

. The Lo uisa generating station is just south of the Muscatine county line with a portion of its property lying across the county line. MidAmerican’s main SO 2 emission source is EP

- 1 (Utility Boiler). MidAmerican also operates two auxiliary boilers (EP

- 2 and EP

- 3) and two emergency generators (EP

- 4 and EP

- 5).

EP

- 1 is a 8,624 MMBtu/hr boiler that is capable of burning coal, #2 fuel oil and natural gas. EP

- 1 is limited to 0.96 lb SO 2 /MMBtu (BACT) (averaged over a 30

- day period), 1.20 lb SO 2 /MMBtu (NSPS D) while burning solid fossil fuel, and 0.80 lb SO 2 /MMBtu (NSPS D) while burning liquid fossil fuel. EP

- 1 is also limited to 3,450 lb SO 2 /hr (averaged over a 30

- day period). The sulfur content of any coal is limited to 2.0 lb/MMBtu or less. EP

- 1 is equipped wit h a lime spray dryer flue gas desulfurization system (scrubber). EP

- 1 is equipped with a SO 2 CEM. EP

- 2 and EP

- 3 are 98 MMBtu/hr boilers that are capable of burning natural gas and #2 fuel oil. EP

- 2 and EP

- 3 are limited to 98.3 lb SO 2 /hr each. The sulfur content of the fuel oil is limited to 0.5% by weight. EP

- 2 and EP

- 3 are not equipped with any SO 2 control system. EP

- 2 and EP

- 3 are not equipped with an SO 2 CEM. EP

- 4 and EP

- 5 are 16 MMBtu/hr emergency generators that are capable of #2 fuel oil only. E P

- 4 and EP

- 5 are limited to 8.4 lb SO 2 /hr each. The sulfur content of the fuel oil is limited to 0.5% by weight. EP

- 4 and EP

- 5 are not equipped with any SO 2 control system. EP

- 4 and EP

- 5 are not equipped with an SO 2 CEM.

Monsanto Company (Monsanto) Monsanto is an agricultural services company that produces on

- site power and heat at its product development facility approximately 9.0 kilometers South

- Southwest of the violating monitor, Monsanto’s main SO 2 emission sources are Boiler #6, #7 and #8. EP

- 33 (Boiler #6) is a 73 MMBtu/hr boiler that is capable of burning fuel oil and natural gas. EP

- 33 is limited to 36.6 lb SO 2 /hr. The amount of fuel oil EP

- 33 can combust is dependent on whether EP

- 45 is burning fuel oil. The sulfur content of the fuel oil is limited to 0.5% by weight. EP

- 33 is not equipped with any SO 2 control system. EP

- 33 is not equipped with an SO 2 CEM. EP

- 45 (Boiler #7) is a 124 MMBtu/hr boiler that is capable of burning fuel oil and natural gas. EP

- 45 is limited to 61.4 lb SO 2 /hr. The amount of fuel oil EP

- 45 can combust is dependent on whether EP

- 33 is burning fuel oil. The sulfur content of the fuel oil is limited to 0.5% by weight. EP

- 45 is not equipped with any SO 2 control system. EP

- 45 is not equipped with an SO 2 CEM. EP

- 195 (Boiler #8) is a 150 MMBtu/hr boiler that is capable of burning coal, sludge (limited) and11 seed corn (limited). EP

- 195 is limited to 292.5 lb SO 2 /hr and 1.95 lb SO 2 /MMBtu (averaged over a 3

- hr period). EP

- 195 is not equipped with any SO 2 control system. EP

- 195 is equipped with an SO 2 CEM. EP

- 21 (Boiler #5) is a 73 MMBtu/hr boiler that is capable of natural gas only. EP

- 21 is limited to 500 ppm SO 2
. Monsanto also operates several small natural gas

- fired emission units and a small diesel
emergenc y generator.

SSAB Iowa, Inc. (SSAB) SSAB Inc. is a steel manufacturer that is located 21.6 kilometers East

- Northeast of the violating monitor, SSAB’s main SO 2 emission source is EP

- 1 (EAF/LMF). EP

- 1 is an electric arc furnace and a ladle metallurgy furn ace. The electric arc furnace has a capacity of 200 tons of liquid steel/hr. EP

- 1 is limited to 0.70 lb SO 2 /ton of steel produced and 613.2 tons SO 2 /yr. EP

- 1 is not equipped with any SO 2 control system. EP

- 1 is not equipped with an SO 2 CEM. SSAB also operates a 371 MMBtu/hr furnace (EP

- 13) that burns natural gas only. EP

- 13 is limited to 0.52 lb SO 2 /hr and 2 tons of SO 2 /yr. SSAB also operates several small natural gas and diesel

- fired emission units.

Gerdau Ameristeel US, Inc. (Gerdau) Gerdau Ameris teel is a steel manufacturer that is located 20.5 kilometers North of the violating monitor. Gerdau’s main SO 2 source is EP

- 01 (which includes the electric arc furnace). The electric arc furnace has a capacity of 90 tons of liquid steel/hr. EP

- 01 is limi ted to 70.2 lb SO 2 /hr and 190 tons SO 2 /yr. There are permit conditions that limit the amount of liquid steel processed, the carbon sources for the electric arc furnace and the amount of natural gas combusted. EP

- 01 is not equipped with any SO 2 control sy stem. EP

- 01 is not equipped with an SO 2 CEM. Gerdau also operates a 150 MMBtu/hr Billet Reheat Furnace (EP

- 04). This furnace burns natural gas only. The SO 2 emissions are limited to 500
ppm. Gerdau also operates several small natural gas and diesel

- fi red emission units.

Meteorology (weather/transport patterns)

Evidence of source

- receptor relationships between specific emissions sources and high SO 2 values at violating monitors is another important factor in determining the appropriate contributing areas and the appropriate extent of the nonattainment area boundary. For this factor, EPA considered recent hourly or sub

- hourly mete orological data from the site nea rest to the violating monitor to de termine which wind vectors might be associated with 1

- hour SO 2 exceedances. For Muscatine County, IA

, the meteorological data used in this analysis were based on 200 9

- 201 1 data from t he National Weather Serv ice Station located 11.4 kilometers from the violating monitor.

Figure 2 lists the frequency of wind direction and wind speed observations associated with the years 2009 through 2011. The winds in Muscatine, IA over the three year period show a patter n of blowing consistently out of the West

- Northwest or South

- South e a st. Winds from the South

- South ea st are in

- line with SO 2 sources located at GPC and Muscatine Power facilities. The GPC facility is the largest source of SO 2 in Muscatine County and Musca tine Power is the third largest source. Additional SO 2 sources in neighboring Louisa and Scott County are not close enough to the violating monitor nor are they inline with the predominant winds to impact the reading at the monitor on days exceedances are observed. I.e., During recorded exceedances at the Muscatine, IA monitor, the winds are coming predominantly from the south in a direction from GPC and Muscatine Power and Water.12 Figure 2: Wind Rose Analysis 2009

- 2011

Geography/ Topography (mountain ranges or other air basin boundaries)

Muscatine County, IA does not have any significant geographical or topographical barriers significantly limiting air

- pollution transport within its air shed ; however, Muscatine County rests on the western shore of the upper Mississippi river . This factor did not play a significant role in determining the nonattainment boundary. The river valley created by the Mississippi River can impact local winds by channeling them along the valley north and south, and can serve t o limit the impact of a particular

source on a monitor sited in proximity to the river valley . In the case of Muscatine, as the Mississippi River flows south it makes a strong bend to the West across the Eastern edge of the county then abruptly turns Sout h again at the City of Muscatine. IA. The existence of the river channel through across the Eastern edge of the county is not expected to impact the emissions observed at the violating monitor located in Muscatine, IA

.13 Jurisdictional Boundaries

EPA re viewed jurisdiction boundary information, including townships, city limits, and a previous SO 2 nonattainment boundary. EPA has elected to propose the nonattainment boundary as the Muscatine County line, which is the default boundary identified by EPA in i ts Designation Guidance.

Other Relevant Information

EPA did not collect additional information relevant to establishing a nonattainment area boundary for
t his area and we believe the information included above is sufficient to satisfactorily establish a n intended nona ttainment area boundary for Muscatine County, IA.

Conclusion

The air quality monitor in Muscatine County shows a violation of the 20 10 SO 2 NAAQS, based on 2008

- 2010 air quality data. As a result Muscatine County or some portion of Muscatine County must be designated as nonattainment. Based upon the consideration of all the relevant and available information, as described above, EPA believes that the boundaries described herein encompa ss the entire area of Muscatine County, Iowa that does not meet (or that contributes to ambient air quality in the area that does not meet) the 2010 SO 2 NAAQS.