Attachment A

Table 1: 2010-2012 Annual PM2.5 Design Values

Monitoring Location Monitor ID Annual PM2.5

Design Value (μg/m3)

Muscatine HS E Campus (Garfield) 191390015 12.2

Muscatine, Franklin School 191390018 11.8

Keokuk, Fire Station 191110008 11.4

Davenport, Hayes School 191630020 11.3

Davenport, Adams Sch. 191630018 11.2

Muscatine, Greenwood Cemetery 191390016 11.1

Council Bluffs, Franklin Sch. 191550009 11.1

Davenport, 10th and Vine 191630015 11.0

Clinton, Rainbow Park 190450021 10.7

Iowa City, Hoover Sch. 191032001 10.5

Waterloo, Water Tower 190130009 10.4

Cedar Rapids, Public Health 191130040 10.3

Sioux City, Bryant School 191930019 9.9

Des Moines, Public Health 191530030 9.7

Clive, Indian Hills School 191532510 9.6

Lake Sugema 191770006 9.6

Viking Lake State Park 191370002 9.2

Emmetsburg, College 191471002 8.8

0.0

3.0

6.0

9.0

12.0

15.0

18.0

Fine Particulate (PM2.5) Design Value 

(micrograms per cubic meter)

Figure 1: Monitored Fine Particulate in Ambient Air in Muscatine 

Compared to the Annual Standard

Muscatine HS E Campus

Greenwood Cemetery

Franklin School

Musser Park Not a Design

Value (*2011-2012 Avg)

1997 Standard (15ug/m3)

2012 Standard (12ug/m3)

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Attachment B

Annual PM2.5 Nonattainment Boundary Recommendation 

for Muscatine, Iowa

Summary

On December 14, 2012, the U.S. Environmental Protection Agency (EPA) revised the primary 

annual National Ambient Air Quality Standard (NAAQS) for fine particulate matter (PM2.5) from 

15.0 μg/m3 to 12.0 μg/m3, based on the latest public health studies. Under the provisions of 

section 107(d)(1)(A) of the Clean Air Act, within one year after EPA promulgates a new 

NAAQS, states must recommend area designations to EPA. States review the most recent 

monitoring data to develop their recommendations on whether the monitoring data shows each 

county or portion thereof in attainment, nonattainment, or unclassifiable with the NAAQS. 

All areas of the state, except one, show attainment with the NAAQS, or are unclassifiable. The 

PM2.5 monitor located at Muscatine High School East Campus has a 2010-2012 annual design 

value that exceeds 12.0 μg/m3, indicating that the area should be recommended for a designation 

of “nonattainment” with the annual PM2.5 NAAQS. A modeling analysis was conducted by the 

Iowa Department of Natural Resources (DNR) regarding possible limitations of the extent of the 

area of nonattainment in Muscatine with the annual PM2.5 NAAQS.

As summarized herein, the recommended boundaries within the City of Muscatine characterize 

the area where violations of the annual PM2.5 NAAQS extend, and include sources that are 

significant contributors to those violations. This document provides technical support for this 

recommendation. Dispersion modeling is appropriate because the boundary recommendation in 

Muscatine County is not influenced by secondary formation of PM2.5 beyond the inclusion of a 

representative background concentration. This dispersion modeling analysis combines emissions 

data and federally enforceable emissions limits, meteorological conditions, terrain information, 

and background concentrations in a peer-reviewed regulatory approach to produce air quality 

data immediately relevant to a boundary recommendation.

Dispersion Modeling Inputs

The modeling analysis was conducted using the most recent version of EPA’s regulatory 

dispersion model, AERMOD (version 12345), National Elevation Dataset (NED) terrain 

elevations, and building downwash parameters for all point sources. As previously approved by 

EPA in the modeling protocol for the SIP call modeling demonstration, meteorological data from 

the Davenport ASOS site for the period 2008-2012 were used. The following major sources of 

PM2.5 were included in the analysis:

• Grain Processing Corporation (GPC)

• Muscatine Power & Water (MPW)

• Union Tank Car (UTLX)

These sources were chosen because they were included in the 24-hour PM2.5 State 

Implementation Plan deficiency modeling demonstration for Muscatine, and as part of that 

analysis were determined to be important contributors to PM2.5 concentrations in the area. 

Hourly PM2.5 emission rates used in the SIP call modeling for these three facilities were used in 

this analysis. The emissions inventories for MPW and UTLX utilized in the modeling were 

based on the post-control PM2.5 emissions levels used in modeling for the 24-hour PM2.5 SIP call 

analysis because those emission levels have been permitted and are federally enforceable. For 

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GPC, the pre-control PM2.5 emissions levels from the SIP call were used because the control 

strategy for GPC is still in the final stages of being permitted and made federally enforceable.

Dispersion Modeling Results

Two modeling analyses were conducted: a culpability test of the impact of each facility at the 

East Campus monitor location, and a full grid analysis to determine the extent of the predicted 

exceedances.

East Campus Monitor Exceedance Culpability

The results of the culpability analysis indicated that neither MPW nor UTLX PM2.5 emissions are 

predicted to have a significant contribution at the East Campus monitor location. The results 

also indicate that GPC emissions have a significant PM2.5 contribution. The maximum

contributions from these facilities at the monitor location are summarized in Table 1. 

Table 1. Maximum Contribution to Predicted Annual PM2.5 Concentrations at East Campus.

Facility Maximum Contribution

(μg/m3)

Significant Impact Level

(μg/m3)

GPC 2.81

MPW 0.27 0.3

UTLX 0.07

Full Grid Analysis

To evaluate the special extent of the area being impacted by PM2.5 emissions, the dispersion 

modeling receptor grid was centered on the East Campus monitor location and extended out to 

ten kilometers. Receptors that fell on the property of any of the three facilities were omitted 

from the analysis. Receptor spacing varied as follows:

• 0-0.5 km: 50-meters

• 0.5-1.5 km: 100-meters

• 1.5-3 km: 250-meters

• 3-5 km: 500-meters

• 5-10 km: 1,000-meters

A default background concentration of 10.5 μg/m3 was added to the results of the analysis. This 

background value is the annual PM2.5 2010-2012 design concentration for the Iowa City monitor. 

The use of this monitor to represent PM2.5 background values in Muscatine was previously 

approved by EPA in the modeling protocol used to address recent exceedances of the 24-hour 

PM2.5 standard in the Muscatine area.

The modeling analysis results indicate that the combined emissions from the modeled sources 

will result in predicted exceedances of the annual PM2.5 NAAQS in the vicinity of the Muscatine 

industrial area adjacent to the Mississippi River.

Proposed Nonattainment Boundary

Based on the ambient air quality monitoring and the dispersion modeling analysis results, Iowa

recommends that a small area of Muscatine County be classified as nonattainment for the annual 

PM2.5 NAAQS.

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Figure 1 identifies the recommended nonattainment boundary (green) and section lines (light 

blue). Major roads and highways are labeled for ease of identification. The suggested 

nonattainment boundary is contained within the Fruitland Township of Muscatine County and 

uses jurisdictional boundaries clearly defined by section numbers (Table 2). 

Figure 1. Recommended Nonattainment Boundary.

Table 2. Legal Description of Recommended Nonattainment Area.

Township Sections

T76N R2W* (Fruitland township) Southern half of 2 and 3

Entirety of 10 and 11

Northern half of 14 and 15

*T = Township and R = Range.

B-3