1

I OWA EPA’s Area Designations f or the 2008 Lead National Ambient Air Quality Standard s

Introduction

EPA has revised the level of the primary (health

- based) standard from 1.5 micrograms per cubic meter (μg/m3) to 0.15 μg/m3 measured as total suspended particles (TSP). EPA has revised the secondary (welfare

- based) standard to be identical in all respects to the primary standard.

Pursuant to section 107(d) of the Clean Air Act, EPA must d esignate as “ nonattainment ” those areas that violate the NAAQS and those nearby areas that contribute to violations.

The tabl e below identifies the portions of a county in Iowa that EPA intends to designate
“nonattainment” for the 2008 lead national ambie nt air quality standard (2008 Lead NAAQS).

Table 1. Iowa Lead NAAQS Nonattainment Areas

Area Iowa Recommended

Nonattainment Count y EPA‟s Designated

Nonattainment Counties Nonattainment area

for 1978 Lead NAAQS

Pottawattamie County Pottawattamie County (partial) defined as:

North

- Avenue G

South

- 23rd Ave

East

- N16th / S 16 th

West

- N 35th

/ S 35th St. Pottawattamie County

(partial) defined as:

North

- Avenue G

South

- 23rd Ave

East

- N16th / S 16 th

West

- N 35th

/ S 35th St. None

Technical Analysis for Pottawattamie County, Iowa Nonattainment Area

This technical analysis for portions of Pottawattamie County identifies the area with a monitor that violates the 2008 Lead NAAQS and evaluates nearby sources for contributions to lead

c oncentrations in ambient air in the area. EPA has evaluated the county based on the weight of evidence of the following factors recommended in EPA guidance:

Air quality in potentially included versus excluded areas;

Emissions and emissions

- related data i n areas potentially included versus excluded from the nonattainment area, including population data, growth rates and patterns, and emissions controls; Meteorology (weather/pollutant transport patterns); Jurisdictional boundaries (e.g., counties, municipalities, political subdivisions of the state, etc.); and

Other relevant inform ation submitted to or collected by EPA.2

Figure 1 is a map of the area analyzed depicting the location and design value of the air quality monitor measuring a violation of the 2008 Lead NAAQS in Pottawattamie County, Iowa, and the potential sources of lead concentrations to ambient air which may be contributing to the violating

monitor.

On March 29

, 2011, the State of Iowa recommended that portions of Pottawatt am ie Coun ty, Iowa, identified in Figure 2 , be designated as “nonattainment” for the 2008 Lead NAAQS based on air quality data from 2009 through 2010 . The state‟s recommendation 1 was based on analysis of monitoring and modeling data

. The IDNR‟s recommended nonattainment area uses conservative modeling and adds a factor of conservatism by extending the recommended boundaries beyond the area where the isopleths indicate that predicted lead concentrations in air

are one

- half the Lead NA AQS.

Based on the technical analysis using currently available information described below, EPA is designating portions of Pottawatt am ie County as nonattainment for the 2008 Lead NAAQS

.

1. Air Quality Data

This factor considers the l ead d esign v alue (in μg/m 3 ) for the air quality monitor in Council Bluffs, Pottawattamie County , Iowa , and the surrounding area based on data collected by the

IDNR from November 3, 2009 to the present

. A monitor‟s design value indicates whether that monitor attains a sp ecified air quality standard ; in this case the 2008 Lead NAAQS the level of

which is 0.15 μg/m 3

. The design value for the monitor in Pottawattamie County is shown in

Table 2

.

Table 2

. Pottawattamie County Air Quality Data

County State

Recommended

Nonattainment? Monitor

Name Monitor

Air Quality System ID Monitor

Location Lead Design

Value

2009

- 2010 (μg/m 3 )

Pottawattamie Yes Griffin Pipe

Monitor ID #191550011 8th Ave & 27 St (41.25425,

- 95.88725 0.26

1 “ Lead Nonattainment Boundary Recommendations, Council Bluffs, IA, Technical Support Documen t,” Iowa Department of Natural Resources, March 29, 201 1.3

Figure 1. Pottawattamie County Lead Nonattainment Area4

Figure 2. State Recommended Lead NAAQS Nonattainment Area

Source: “ Lead Nonattainment Boundary Recommendations, Council Bluffs, I A, Technical Support Documen t,” Iowa Department of Natural Resources, March 29, 2011.5

A violation of the 2008 Lead NAAQS fo r the monitor listed in Table 2 above was measured b y a monitor in Pottawattamie County, Iowa. Therefore

, some area in the county and possibly additional areas in surrounding counties must be designated nonattainment. The absence of a violating monitor alone is not a sufficient reason to eliminate nearby counties as candidates for

nonattainment status. Each area has been evaluated based on the weight of evidence of the eight factors (collectively combined into five like groupings) and other relevant information.

The viol ating monitor is depicted i n Figure 3 below. The violatin g monitor is a Federal Equival ent Method (FE M) monitor in the predominant downwind direction , approximately 0.1

miles from the Griffin Pipe Corporation Products (Griffin Pipe) facility

. Data from the monitor

from November 2009 through December 2010 have been quality assured by IDNR

. As Table 3 below indicates, the monitor violated the standard in six rolling three month periods in 2010.

Table 3. 3

- Month Rolling Averages for Lead Pottawattamie County Ambient Air Monitor

Dates 3

- Month Rolling Average (μg/m 3 ) 2008 Lead NAAQS Violation

Nov ‟09

– Jan „10 0.10

Dec ‟09

– Feb „10 0.03

Jan

– Mar 2010 0.07

Feb

– Apr 2010 0.12

Mar

– May 2010 0.14
Apr

– Jun 2010 0.17 X
May

– Jul 2010 0.20 X

Jun

– Aug 2010 0.26 Maximum

Jul

– Sep 2010 0.24 X
Aug

– Oct 2010 0.25 X
Sep

– Nov 2010 0.18 X

Oct

– Dec 2010 0.146

Figure 3. Location of Pottawattamie County Ambient Air Monitor for Lead

Source: “ Lead Nonattainment Boundary Recommendations, Council Bluffs, IA, Technical Support Documen t,” Iowa Department of Natural Resources, March 29, 2011.

2. Emissions and Emissions

- Related Data

Evidence of le ad emissions sources in the vicinity of a violating monitor are an important factor for determining whether a nearby area is contributing to a monitored violation. For this factor,

E PA evaluated county level emission data for lead

.

Table 4 below shows total emissions of lead for sourc es greater than 0.1 tons per year (tpy) in

and around the recommended Pottawattamie County nonattainment area

. Emissions data were generally der ived from the 2008 National Emissions Inventory, version 1.5 (NEI08V1.5)

. NEI08V1.5 was the most current version of the national inventory available in 2011 when these data were compiled for the designations process ( http://www.epa.gov/ttn/chief/net/2008nei_v1/lead_facility_v1_5_final.xls )

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Table 4 . Lead Em issions for Pottawattamie County

County

State Facility in State

Recommended

Nonattainment

Area ? Facility

– Total Ai r

Emissions (tpy ) Facility Total County

Lead Emissions (tpy)

Pottawattamie Iowa Yes 0.59 1 Griffin Pipe 1.2 1

Pottawattamie Iowa No 0.58 1 MidAmerican

– Walter Scott Energy Center 1.2 1

1

– NEI08V1

Both the Griffin Pipe facility and the MidAmerican

– Walter Scott Energy Center (WSEC), a power plant approximately 5.5 miles south

- southeast of Griffin Pipe and the violating lead monitor, reported lead emissions greater than 0.5 tpy. WSEC, depicted in relation to the Griffin Pipe facilit y and violating monitor in Figure 4 below, operates four coal

- fired electric generating units. The coal used to fuel the electric generating units at WSEC naturally contains lead which is released into the atmosphere from the burning coal. IDNR conducted modeling for this facility and requested a waiver from lead monitoring in its 2010 Network Monitoring Plan (IDNR 2010) . As discussed in Section 9.0, Other Relevant Information, modeling for the

nonattainment area recommendation demonstrates the WSEC faci lity does not contribute to the Lead NAAQS violation at the monitor. The modeled contribution of WSEC to the

nonattainment area was 0.0006 μg/m 3 which is less than 1% of the Lead NAAQS.

There is one airport facility in Douglas County , Nebraska, which is directly north of the Griffin Pipe facility, with aircraft using leaded aviation gas th at emits 0.1 tpy of lead. It is the Eppley Airfield (KOMA) in Figure 4 below. The state did not provide analyses (such as air quality modeling) to exa mine the potential impact of this airport on the violating monitor. 2

2 There are approximately 20,000 airport facilities in the U.S. at which leaded aviation gasoline is consumed. Leaded aviation gasoline is used almost exclusively in piston

- engine aircraft. Emissions data from the 2008 National Emissions Inventory version 1 (NEI08V1) is the most accurate depiction for the airport facilities in the United States, and NEI08V1 data was used in evaluating emissions from these facilities.8

Figure 4. Omaha

– Council Bluffs Area Lead Sources

3. Population Data

, Growth Rates and Patterns

Table 5 shows the 2008 pop ulation for Pottawattamie County, Iowa

, which includes the proposed nonattainment area

. These data help assess the extent to which the concentration of human activities in the area and concentration of population

- oriented commercial development may indicate emissions

- based activity contributing to elevated ambient lead levels. This may

include ambient lead contributions from activities that would disturb lead that has been deposited on the ground or on other surfaces . Re

- entrainment of historically deposited lead ty pically is not reflected in the emissions inventory

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Table 5 . Population Data

County State Recommended

Nonattainment? 2008

Population 2008

Population Density (pop/sq mi) Population

Change

2000

- 2008 Population

% Change

2000

- 2008

Pottawattamie County, Iowa Yes, partial 89,647 94 1682 2

Source: U.S. Census Bureau estimates for 2008 ( http://www.census.gov/popest/datasets.html )

This factor considers population growth for 2000

- 200 8 in the area considered for the nonattainment designation. Table 5 above shows popula tion and population growth for Pottawattamie County, Iowa . All population data is from the U

. S

. Census Bureau http://www.census.gov/popest/counties/CO

- EST2008

- popchg2000_2008.html

.

Population in Pottawattamie County grew a modest 2%. Population growth is not expected to correlate with increases in lead emissions. Significant c hanges in industrial activity within the county that would cause an increase in area lead concentrations are difficult to predict, but are not anticipated. EPA has considered the population growth rate for this area and does not

believe that it affects th e boundary determination.

4. Emissions Controls

Under this factor, the existing level of control of emission sources is taken into consideration. The emissions data used by EPA in this technical analysis and provided in Table 4 above represent emissi ons levels taking into account any control strategies implemented on stationary sources in Pottawattamie County before 2008

.

The Griffin Pipe facility has recently implemented air pollution control activities as a part of its Prevention of Significant D eterioration (PSD) permitting (IDNR 2011) . The PSD project was required to resolve a significant (> 0.6 tpy) increase in lead emissions which occurred at the facility. Activities included: replacement of the existing wet scrubber system for the cupola furnace with a baghouse; addition of a second baghouse to control emissions from the magnesium inoculation and desulfurization processes; and installation of two new chemical storage silos, one for a chemical that will be added to the gas stream after exiting cupola and before the baghouse for sulfur dioxide control, and the other for a chemical to be added to the gas stream for the treatment of heavy metals in the baghouse. The air pollution c ontrol equipment was installed in order to demonstrate that the facility meets the Best Available Control Technology (BACT) criteria. The facility must also utilize a scrap management plan to control the amount of lead contained in the scrap metal it proc esses. The final PSD permit was issued on December 7, 2010. The baghouses have been operational since January 2011. Implementation of the PSD project is expected to greatly reduce lead air emissions.10

5. Meteorol

ogy

For this factor, EPA considered da ta from 32 years of National Weather Service average frequency of wind direction by season. The data on meteorology are depicted in Figure 5 below. These data may provide evidence of the potential for lead emissions sources located upwind of a violating monitor to contribute to ambient lead levels at the violation location.

Figure 5. Wind Direction Frequencies

The three

- dimensional bar chart above shows the wind frequencies in eight dire ctions for the

four seasons. The chart frequencies reflect the directions from which the winds come. Based on Figure 5 , it may be concluded that the wind ori ginates predominately from the north

- northwest ( N NW ) in th e winter months and from the east

- southeast ( ESE ) during summer months.

In its analysis, IDNR used data from the nearest Automated Surface Observing System (ASOS) meteorological station located at Eppley Airfield (KOMA) in Omaha, Nebraska (IDNR 2011)

. KOMA is approximately 3 miles to the north

- northw est (NNW) of Griffin Pipe monitor in Council Bluffs, Iowa. Based on the data from the ASOS meteorological station at KOMA, IDNR concluded that the predominant wind directions were NNW and south

- southeast (SSE).

Wind direction appears to have a strong inf luence on lead concentrations at the violating

monitor . IDNR‟s analysis concludes that on days when the 24

- hour average lead concentrations

exceed 0.15 μg/m 3 , winds are typi cally out of the SSE (IDNR 2011)

. Further, IDNR concluded11

that winds from the NNW , which also occur frequently, are rarely measured on days for which high lead concentrations are measured in the air monitor.

6. Geo graphy/Topography

The geography/topography analysis evaluates the physical features of the land that may have an

e ffect on the air shed and, therefore, on the distribution of lead over the proposed Pottawattamie

Count y nonattainment area

.

Council Bluffs is located on the eastern banks of the Missouri River and extends eastward into Pottawattamie County. The topography of Po ttawattamie County consists of flat river bottoms from three to 10 miles wide along the Missouri River. Bluffs extending 100 to 300 feet above the floodplain demark the extent of the generally flat river bottoms. Further east in Pottawattamie County the terrain transitions into areas of steep ravines and hills, followed by gently rolling prairie (IDNR 2011)

.

The proposed nonattainment area does not have any geographical or topographical barriers significantly affecting air pollution transport within its air shed. Therefore, this factor did not play a significant role in determining the nonattainment boundary.

7. Jurisdictional boundaries

Existing jurisdictional boundaries may be helpful in determining a boundary for purposes of nonattainment designation s, and for purposes of carrying out the governmental responsibilities of planning for attainment of the lead NAAQS and implementing control measures. These existing boundaries may include an existing nonattainment 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.

In the ar ea surrounding the violating monitor, the proposed nonatta inment area lies within the jurisdictional boundary of the City of Council Bluffs, Iowa. The City of Council Bluffs encompasses approximately 39.7 square miles (IDNR 2011)

. Based on the modeling data which are described in Section 9 below, IDNR recommende d a nonattainment area that is considerably smaller than the city limits. Rather, t he IDNR recommended nonattainment area is defined by

ma jor roadways that it believes are durable and more recognizable to the public. This is reasonable considering the che mical properties of lead: elemental lead and lead compounds area heavier and tend to deposit from ambient air faster and in a shorter distance from the source than lighter molecular weight pollutants

.

8. Other Relevant Information

EPA received additional information from the State relevant to establish a nonattainment area boundary for portions of Pottawattamie County, Iowa. As briefly mentioned above, I DNR submitted the results of a dispersion model analysis in support of its boundary12

determination. EP A considered this information and conducted an independent analysis in making its boundary determin ation for the Pottawattamie County nonattainment area.

In accordance with the Lead NAAQS Final Rule, the presumptive boundary of the nonattainment area is the entire county with a violating monitor. The State and/or EPA may conduct additional

area

- specific analyses that could lead to a departure from the pres umptive boundary.

Boundaries may be recommended on the basis of one or any combination of the following techniques in addition to the eight

- factor analysis:

Qualitative analysis; Spatial interpolation of air quality monitoring data; or Air quality simulation by dispersion modeling.

IDNR elected to use dispersion modeling for making its boundary recommendation to EPA. EPA evaluated IDNR‟s analysis and conducted independent verification and analysis as

discussed below.

IDNR used AERMOD, EPA‟s prefe rred dispersion model for the analysis conducted. The modeling was performed for two scenarios: absent baghouse controls using actual emissions rates based on stack testing conducted in March 2010; and with baghouse controls installed in January 2011 usi ng BACT emissions limits specified in the facility‟s air construction permit for the PSD project. Emissions modeled under this scenario were 0.2 8 lbs lead per hour, or 1.23 tpy (IDNR 2011) , which is approximately a factor of two greater than the faciliti es emissions reported emissions of 0.58 tpy listed above in Table 4.

Other potential sources of lead from the area , including power plants and cement kiln discussed

in Section 2 above

, were modeled based on potential to emit. The WSEC facility, which is approximately 5.5 miles from Griffin Pipe and the violating monitor, had the greatest

contribution to the nonattainment area of all the Iowa and Nebraska sources of lead emissions modeled. The modeling determined that WSEC contributed 0.0006 μg/m 3 of lead to the receptor grid area, which is less than 1% of the level of the Lead NAAQS. Therefore, the modeling confirms that the Griffin Pipe facility is the source of lead measured at the violating monitor.

In IDNR‟s model scenario absent baghouse controls, v iolations of the NAAQS were predicted to extend approximately one

- third mile to the north and one

- fourth mile to the south from the Griffin Pipe facility (Figure 6) . The highest predicted lead concentration for this scenario, 0.60
μg/m 3

, occurred along the southern boundary of the facility near the cupola stack. There is a sharp decrease in the lead concentrations as the distance from the facility increases, as would be predicted based on the physical properties of lead.

As Figure 7 bel ow indicates, in the scen ario with baghouse controls, the predicted lead concentrations are below the Lead NAAQS. The highest lead concentration predicted by the

model in this scenario was 0. 054 μg/m 3

. Concentrations of lead for the potential lead

- emitti ng facilities remained the same in the scenario modeled with baghouse controls because the only13

change in this scenario specifically relates to air pollution control equipment installed at the Griffin Pipe facility; the model inputs for the other facilitie s remain ed the same.

Using the outcomes of its modeling effort and its eight

- factor analysis, the IDNR recommended boundaries for the Lead NAAQS nonattainment area depicted in Figure 2 above. The IDNR‟s

recommended nonattainment area is based upon the us e of the most conservative model run, the scenario absent baghouse controls, and adds a factor of conservatism by extending the recommended boundaries beyond the area where the isopleths indicate that predicted lead

concentrations in ambient air are one

- ha lf the Lead NAAQS.

EPA conducted an independent review of IDNR‟s model and determined the modeling effort was generally comprehensive and done in accordance with EPA modeling guidance (Daye 2011) . EPA‟s model output for the absent baghouse controls sce nario is depicted in Figure 8

below.

Conclusion

EPA is designating portions of Pottawattamie County, Iowa which include the Griffin Pipe facility in Figure 2 as the nonattainment area for the 2008 Lead NAAQS . The boundaries of the proposed nonattainment area are based on major roadways in Council Bluffs, Iowa as follows:

North

- Avenue G

South

- 23rd Ave

East

- N16th / S 16th

West

- N 35th/ S 35th St.

The air quality monitor in Pottawattamie County located NNW of the facility shows v iolation s of

the 2008 Lead NAAQS based on 2009

- 2010 air quality data. Therefore, a nonattainment designation is required for all or some of Pottawattamie County. The eight

- factor analysis and other relevant information, including modeling results, supports a partial county designation for Pottawattamie County.

Based on its consideration of all the relevant, available information, as described above, EPA believes that the boundaries described herein encompass the entire area that does not meet (or that contributes to ambient air quality in a nearby area that does not meet) the 2008 Pb NAAQS.14

Figure 6. IDNR Air Dispersion Model Results

- Absent Baghouse Controls15

Figure 7

. IDNR Air Dispersion Model Results

– w ith Baghouse Controls16

Figure 8. EPA Air Dispersion Model Result

– Absent Baghouse Controls17

References

“ Iowa Ambient Air Monitoring 2010 Network Plan ,” Iowa Department of Natural Resources,

June 2010.

“ Lead Nonattainment Boundary Recommendations, Council Bluffs, IA, Technical Support

Documen t,” Iowa Department of Natural Resources, March 29, 2011.

Daye, Richard. Email c orrespondence to Stephanie Doolan, U. S. E nvironmental P rotection

A gency (EPA) Region 7

, A ir P lanning and D evelopment B ranch , dated May 27, 2011.

Definition of important terms used in this document:

1) Designated “ nonattainment ” area

– an area which EPA has determined, based on a State

recommendation and/ or on the technical analysis included in this document, has violat ed the 2008 Lead NAAQS

, based on the most recent three years of quality assured air quality monitoring data from 2008

- 20 10 including at least one valid three

- month site mean above the level of the 2008 Lead NAAQS, or that contributes to a violation in a nearby area

.

2) Designated “ unclassifiable/ attainment” area

– an area which EPA has determined does not contribute to a violation of the 2008 Lead NAAQS in a nearby area and either: (1) meets the 2008 Lead NAAQS, based on the most recent three years of quality assured air quality monitoring data from 2008

- 2010 includ ing 36 consecutive valid three

- month site means (including the last two months of 2007), or (2) has no monitors or has incomplete air quality monitoring data for 2008

- 2010 but has no violations of the 2008 Lead NAAQS.

3) Designated “unclassifiable” area

– an area which EPA has determine d cannot be classified on the basis of available information as meeting or violating the 2008 Lead NAAQS

, based on

the most recent three years of quality assured air quality monitoring data from 2008

- 20 10, but for

which ava ilable monitoring data from the same or a recent period indicate a significant likelihood that the area may be violating the 2008 Lead NAAQS.

4 ) Violating monitor

– an ambient air monitor whose valid design value exceed s 0.15 micrograms per cubic meter ( ug/m3) . As described in Appendix R of 40 CFR part 50, a violation

can be based on either Pb

- TSP or Pb

- PM10 data and only three months of data are necessary to produce a valid violating design value.

5 ) 1978 Lead NAAQS

– 1.5 μg/m 3 , National Ambient Air Qu ality Standard for lead promulgated in 1978. Based on Pb

- TSP indicator and averaged over a calendar quarter.

6 ) 2008 Lead NAAQS

- 0.15 μg/m 3 , National Ambient Air Quality Standard for lead promulgated in 2008. Based on Pb

- TSP indicator and a three

- mon th rolling average. Pb

- PM10

data may be used in limited instances, including to show nonattainment.