MEMORANDUM 

SUBJECT: Technical Support Document (TSD) for the Iowa State Implementation Plan (SIP) 

Revision for Fine Particulate Matter, Muscatine, Iowa 

FROM: Amy 

Community 

Algoe-Eakin Partner- \ ~~~ ms Section, 

Air Planning and Development Branch 

THRU: 

Sara Hertz Wu~~~/J , 

On detail to Air ~dft>evelopment Branch 

Michael Jay, Section Chief 

Atmospheric Programs Section, 

Air Planning and Development Branch 

Joshua Tapp, Branch Chief 

Air Planning and Development Branch 

TO: IA-167; EPA-R07-0AR-2014-0550 

I. INTRODUCTION 

This Technical Support Document (TSD) provides information regarding the Iowa State Implementation 

Plan (SIP) revision submitted to address the July 14, 2011, U.S. Environmental Protection Agency 

(EPA) finding that the existing Iowa SIP was substantially inadequate to maintain the 2006 24-hour 

National Air Quality Standard (NAAQS) for fine particulate matter (PMz.s) in Muscatine County, Iowa 

(76 FR 41424 ). As a matter of clarification, EPA refers to the Agency's notice of substantial inadequacy 

as a "SIP Call," which directed the state to strengthen their SIP. 

In addition, this TSD provides the following information: 

1. provides regulatory background for this Agency action; 

2. summarizes the current ambient air quality monitoring data for the 2006 PMz.s NAAQS at the 

violating monitor; 

3. provides EPA's evaluation ofthe state's submittal; and 

4. includes the recommended action for Iowa's SIP. 

. Printed on Recycled Paper 
monitoring data. The monitoring data illustrated that the area tended to oscillate above and below the 

standard. The monitoring data is discussed in more detail in Sections IV. and V. B. of this TSD. 

To issue the SIP Call and address the violating monitor, EPA relied upon Section 110(k)(5) ofthe Clean 

Air Act (CAA). Section 110(k)(5) provides, in relevant part, that "[w]henever the Administrator finds 

that the applicable implementation plan for an area is substantially inadequate to attain or maintain the 

relevant national ambient air quality standard ... the Administrator shall require that state to revise the 

plan as necessary to correct such inadequacies." Specifically, the SIP Call established the following: 

• the Iowa SIP was substantially inadequate to maintain the NAAQS for 24- hour PM2.s in the 

area; 

• required Iowa to revise and submit to EPA a SIP to meet all of the applicable requirements of 

section 110 ofthe Act with respect to PM2.s in the area, including'an emissions inventory, 

modeled attainment demonstration, adopted control measures cind contingency measures as 

described in EPA's February 2, 2011, proposal; 

• required the State to submit revisions to the SIP within 18 months of the effective date of this 

rule; 

• required that all adopted measures to achieve reductions determined necessary to attain and 

maintain the 2006 24-hour PM2.s standard be implemented no later than years after the 

issuance of the rule; and 

• required that the SIP provide for attainment and maintenance of the 2006 24-hour PM2.s NAAQS 

in the Muscatine County, Iowa area as expeditiously as practicable. 

III. CHRONOLOGY OF SIP ACTIVITIES 

ACTION DATE 

EPA's Finding of Failure to Submit Issued July 14, 2011 EPA's Finding ofFailure to Submit Effective August 15, 2011 

May 23, 2013- first public notice 

November 15, 2013- second public 

Muscatine PM 2.s SIP Proposed notice 

June 24, 2013 - first hearing 

Public Hearing December 18, 2013- second hearing 

SIP Approved by Iowa's Environmental Protection 

Commission February 18, 2014 

Rule package received by EPA, R 7 February 24, 2014 

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assured data. 

Clean Air Act section 110(a)(2)(B) requires each state to establish and operate appropriate 

devices, methods, systems and procedures necessary to monitor, compile, and analyze data on 

ambient air quality. Pursuant to this authority, the state maintains a network of air quality 

monitors for PM2.s in accordance with 40 CFR Part 58 which meets applicable requirements. 

Monitors called State or Local Air Monitoring Stations (SLAMS) make up the ambient air 

quality monitoring sites whose data are primarily used for determining compliance with the 

NAAQS. In Muscatine, there are 3 SLAMS monitors. One monitor is located at the Garfield 

Elementary School and is referred to as the "Garfield School monitor." Historically, the Garfield 

School monitor has recorded fluctuating PM2.s values very near or above the NAAQS. EPA 

based its SIP Call on the recorded violations of the 24-hour PM2.s NAAQS at the Garfield School 

monitor. 

Table 1 includes past and most recent design values at the Garfield School monitor, including the 

certified SLAMS data for calendar year 2013, submitted by Iowa on April 30, 2014, in 

accordance with 40 CFR Part 58. As noted on this table, since EPA's July 2011 finding, there 

has been a decrease in monitored concentration of PM2.s. Figure 1 visually displays eleven years 

of 24-hour PM2.s monitoring data. As indicated in Figure 1, the ambient air quality monitors 

values are declining. Although Table 1 and Figure 1 capture only data from the Garfield School 

monitor, the two additional monitors in Muscatine remain in compliance with the 24-hour PM2.s 

NAAQS. 

Table 1. Design Values at the Garfield School Monitor 

Monitoring Years Design Value (J.lg/m3) 

2001-2003 35 

2002-2004 35 2003-2005 38 2004-2006 34 2005-2007 36 

2006-2008 35 

2007-2009 38 

2008-2010 37 2009-2011 35 2010-2012 32 2011-2013 28 

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2001- 2002- 2003- 2004- 2005- 2006- 2007- 2008- 2009- 2010- 2011· 

2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 

-+-Series1 35 35 38 .34 36 35 38 37 35 32 

Years 

V. ANALYSIS OF CLEAN AIR ACT REQUIREMENTS 

Consistent with Section 11 0 of the Clean Air Act and the requirements included in the SIP Call, 

the State submitted the required plan elements to correct the inadequacy of the SIP. These 

specific elements are: 

(1) a revised emission inventory for all sources that could be expected to contribute to the 

violating monitor because of their size, proximity, or other relevant factors consistent 

with 40 C.F.R. § 51.114(a); 

(2) a modeling demonstration to achieve reductions determined necessary to attain and 

maintain the NAAQS, with enforceable schedules for attaining the NAAQS as 

expeditiously as practicable; 

(3) adopted measures to achieve reductions determined necessary to attain and maintain 

the NAAQS, with enforceable schedules for implementing the measures as expeditiously 

as practicable; 

(4) contingency measures that will be triggered if the monitoring value is above the level 

of the standard in the calendar year following the implementation of controls necessary 

for attainment. If triggered, the contingency measures would need to be implemented in 

an expeditious and timely manner. 

A. Emissions Inventory 

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to violations of the 24

hour PM2.s NAAQS. Building upon the technical analysis which occurred 

during the designations process for the 2006 24-hour PM2.s NAAQS and in reviewing inventory 

for the development of modeling, the state determined three sources significantly contributed to 

the Garfield School monitored violations: Grain Processing Corporation (GPC), Muscatine 

Power & Water (MPW), and Union Tank Car (UTC). Because of the form of the standard (24-

hour average), local sources were determined critical in terms of contributions to ambient PM2.s 

concentrations. The state did not identify any other potential emissions sources in the area of the 

violating monitor, such as area and mobile sources, as contributing significantly to the NAAQS 

violations. Background concentrations were added to modeled results to account for the regional 

transport of fine particulate matter and any unidentified local sources, such as mobile and area 

sources, not explicitly included in the model. 

Table 2 is a listing of the three facilities and their PM2.s emissions. The actual emissions 

represent direct PM2.s emissions that were reported by the facilities to the DNR on the annual 

emissions inventory questionnaires. PM2.s actual emissions values for many ofGPC's emission 

points were further refined using hourly emission rates derived from a combination ofPM10 and 

PM2.s stack testing data and information regarding the fraction of PM2.s in emissions sampled by 

GPC. 

Table 2: Facility-Wide Actual PM2.s Emissions 

Actual PM2.s Emissions 

Facility Name Facility ID _(tonsll'_ealj_ 

Grain Processing Corporation 70-01-004 537.6 

Muscatine Power & Water 70-01-011 58.3 

Union Tank Car Company 70-01-048 3.0 

Total 598.9 

B. Modeled Attainment Demonstration 

In the SIP Call, EPA required the state to submit a modeled attainment demonstration which is 

consistent with 40 CFR part 51, Appendix W. 40 CFR part 51. The modeling was required to 

demonstrate what reductions will be needed to attain and maintain the PM2.s NAAQS in the area. 

The state adequately addressed this requirement in its SIP revision. 

The SIP Revision includes a detailed explanation of the modeling conducted. Included in the 

state's plan is a discussion of model selection and options including: the extent of the receptor 

grid, receptor grid spacing, terrain elevations, downwash, and meteorological data. The state also 

provides background as to the iterative analyses conducted as well as the detailed development 

of model inputs for emissions and meteorology. 

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7 believes the state SIP revision to be consistent with EPA's modeling requirements. Because 

local point sources are considered to be the significant contributors to the monitor's 24-hour 

PM2.s violations, the state's modeling was conducted using AERMOD version 12345. Again, the 

model selection, modeling inputs such as background concentrations and significant impact 

levels, and results of modeled attainment tests were subject to consultation with EPA Region 7 

before completion of the control strategy selection. 

C. Adopted Control Measures 

In order to meet the requirements of the SIP Call, Iowa developed a control strategy for 

Muscatine County that includes the three sources that Iowa determined contributed to the 

monitored violations at the Garfield School monitor. 

1. GPC 

Grain Processing Corporation or GPC is located approximately 500 meters east/southeast of the 

Garfield School monitor. GPC processes grain into industrial, beverage, and fuel-grade ethanol, 

grain based food products, industrial products, and animal feeds. GPC has nearly 200 PM2.s 

emission points, including coal and gas-fired boilers, dryers, coolers and associated material 

handling and storage equipment. GPC's facility is 70 years old. It is located on 135 acres 

immediately adjacent to the Mississippi River. The facility has grown over time through the 

expansion of various processes in accordance with demand and product development and by 

acquiring land adjacent to its original location. The facility footprint is very limited and is 

bounded by residential property on the north and west, and a municipal utility property on the 

south. Because of the location, the existing plant has minimal unused space for plant 

modifications and additional equipment. 

Iowa's control strategy for GPC is memorialized in Administrative Consent Order No. 2014-AQAl (" ACO") and is included as part oflowa's SIP revision, as SIP Attachment B1• The ACO 

includes a schedule for implementing the control strategy as well as recordkeeping, reporting, 

and testing requirements. The provisions of the ACO will be incorporated into permits, which 

will then be submitted to EPA for approval into the state SIP. The control strategy includes 

numerous and substantial changes at the facility. The control measures include: new particulate 

controls or improvements to existing particulate controls on a number of sources; shutdown of 

existing equipment; replacement of old equipment; installation of more efficient equipment; 

1 As stated in Iowa's SIP submission letter of February 18, 2014, Iowa did not submit Section III, Paragraph 5, the 

last sentence, or Section VI to EPA for approval. therefore, those provisions of the 2014 ACO are not part oflowa's 

SIP and are not considered by EPA. 

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Due to the scale and complexity of the control measure implementation at GPC, GPC has 

developed a phased implementation schedule that is already underway and concludes in 

December 2016. Many of the changes at GPC are contingent upon completion of a significant 

project related to a new dryer house (Dryer House #5 or DH 5) that was required under the 2006 

Consent Order entered into between GPC and the State of Iowa to address PM to emissions. This 

project is also included in Iowa's SIP revision to address the 2006 PM2.s NAAQS. 

The DH 5 project is a $75 million feed dryer installation. The dryer is a Swiss Combi dryer, 

which is a state-of-the-art feed drying system that is partially designed and manufactured 

overseas. All the buildings that are to be constructed for this project are enclosed under a single 

structure. DH 5 and the associated equipment will be located on the floodplain of the Mississippi 

River, which is comprised of loose, sandy soil. Therefore, special structural footings must be 

designed and installed. In order to connect DH 5 to the existing plant, GPC must tie-in DH 5 in a 

staged fashion that requires coordinated, planned process shutdowns. 

The SIP Call occurred at the same time GPC was in process of designing the DH 5 project to 

comply with the 2006 Consent Order. To demonstrate compliance with the PM2.s SIP Call, GPC 

re-evaluated the DH 5 project and made adjustments to the design to accommodate the more 

stringent plant-wide changes required by the PM2.s SIP Call. As a result of the changes to the 

project to comply with the PM2.s SIP Call, the design complexity and construction logistics for 

the DH 5 project, GPC will complete the project on March 31,2015. The control strategy 

includes several large scale projects that are tied to the installation and completion of the DH 5 

project. They are described below. 

GPC will route the Dryer House 4 (DH 4) milling systems through a new baghouse and remove 

six emission points. This project requires modifications to multiple stories of the existing DH 4 

process building; multiple new pneumatic transportation and cooling systems for product that 

leaves the existing dryers 5, 6, and 7; a product pneumatic receiving baghouse2; a high static 

induced draft fan, an airlock, spouting and a mill. The completion of this project is tied to the DH 

5 project as well as several other projects in the control strategy. The DH 5 project will replace 

eleven existing, operating dryers. The space required for the new DH 4 milling system is 

occupied by equipment that is currently operating, but will be replaced by the DH 5 project. 

Therefore, the DH 4 milling system project requires coordinated process shutdowns for the 

completion of tie-ins through this area of the plant. DH 5 must be on-line to allow for shutdown 

and tie-in of other sources. Due to the careful coordination needed to systematically shutdown 

and tie-in the DH 4 milling system, GPC will complete the project 12 months after the startup of 

DH 5, by March 31,2016. 

2 Product enters the baghouse on a pneumatic conveyor belt. 

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drying capacity of the Gluten Plant 1 #3 Dryer. For normal plant operation to occur during the 

DH 5 project, the #3 Dryer must be in operation until DH 5 can accommodate the load. The #3 

Dryer will be shut down within 30 days of the startup and operation ofDH 5, which will be by 

April 30, 2015. As a result of the DH 5 project, GPC will add and remove certain emission points tied to the 

project. The new emission points are associated with DH 5 and will come online by March 31, 

2015. The remaining sources that will be decommissioned are associated with drying systems, 

including feed dryers, product handling and/or milling systems that will be replaced by DH 5. As 

DH 5 comes online the sources will be taken off line. They cannot be taken off line until DH 5 is 

fully operational because drying of feed is essential to keep the plant in operation. GPC will add 

and remove the sources by March 31, 2015. 

GPC will modify the Spray Dryer #3 Maltrin Scrubbers and extend all Maltrin stacks. This 

project has a complex scope of work. Spray dryer #3 at Maltrin has two stacks, each with a 

venturi scrubber. Both scrubbers will be modified during this project. GPC will add packed bed 

sections that must be designed specifically for those scrubbers. GPC plans to complete nine 

separate stack extensions on the Maltrin building roof. The structural cages and trusses for these 

extensions must be designed, fabricated, and installed. In order to minimize disruption to 

production, GPC must plan and coordinate this modification with the other projects that are 

occurring at the facility. This project also requires tie-ins to several other projects, including DH 

5. GPC will complete this project by September 1, 2016. 

GPC will install scrubbers on DH 4 rotary dryers 5, 6, and 7, and relocate the stack. This is 

another project that has an extensive and complex scope of work. GPC will install three separate 

scrubber systems, including scrubbers, fans, circulation pumps, heat exchangers, and filters. To 

accommodate a scrubber and a stack extension, the existing stacks will be abandoned and new 

stacks will be installed at a different location. GPC must make structural modifications to the 

south side of the DH 4 building to accommodate the scrubber equipment and new stacks. GPC is 

also undertaking feed milling modifications at DH 4 as described above. Because this project is 

tied to both the feed milling modifications and the DH 5 project, GPC will complete this project 

by November 1, 2016. GPC must delay the start ofthe scrubber installation until DH 5 is fully 

operational because DH 5 must accommodate the additional dryer feed load that will be lost 

during the installation of the scrubbers on the rotary dryers. 

The control strategy also includes several large scale projects that are complex in all aspects, 

including design and construction and will require an extended schedule to complete. 

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Gluten Plant Units 1 and 2. These improvements also involve an increase in the stack height to 

140 feet. The addition of an additional gluten rotary vacuum filter at Gluten Plant 2 will improve 

all aspects of gluten drying at the plant and will allow GPC to effectively reduce average 

dewatering and drying from Gluten Plant 1 to allow GPC to shift the process to the Gluten Plant 

2 dryer. This will allow GPC to run the Gluten Plant Unit 1 dryers at a consistently lower rate, 

which will reduce fine particulate emissions from the Gluten Plant Unit 1 dryers and the existing 

scrubber and make the gluten drying process more efficient. 

GPC will submit a permit application for the additional gluten rotary drying vacuum filter at 

Gluten Plant 2. The final design and construction planning cannot begin until after the permit has 

been obtained from Iowa. 

The existing scrubber stack extension will require design, fabrication, and construction of a 

structural truss, tied back to the existing steel, for structural support. Process shutdowns at 

Gluten Plant #1 and other processes at the facility will have to be coordinated to allow for the tiein to the scrubber. The additional gluten rotary drying vacuum filter to be installed at Gluten 

Plant Unit 2 will allow GPC to maintain production while the drying load from Gluten Plant 1 is 

shifted to the Gluten Plant 2 dryer. GPC will upgrade the packing and flow through the existing 

scrubber during the scheduled shutdown of Gluten Plant 1. Multiple shutdowns will be required 

to allow for tie-ins to complete this project. GPC expects to complete this project by August 1, 

2016. 

GPC will decommission all the P&S dryers and convert flash dryers 1 and 2 to natural gas. GPC 

must obtain permits to convert flash dryers 1 and 2 to natural gas. GPC expects that the 

permitting process will take 9-12 months to complete. GPC has already begun working on the 

burner and stack design for this project. The conversion will require a complete re-design of both 

flash dryers including large inlet ductwork systems, design ofburner and burner management 

sections; contractor review of burner design and fuel safety provision, removal of existing steam 

coils, steam and condensate handling, piping, and equipment. This project requires new 

ductwork which will be designed, built, and installed to accommodate the new burner sections 

and allow space for heat recovery coils to be installed. This project requires civil/structural 

design, burner ·duct design, bid package generation, mechanical and electrical contracts, and 

procurement of materials. As with the other projects, each piece will need to be shutdown in a 

coordinated fashion in order to meet customer demand. Due to the complexity with design, 

engineering, and construction of this project, GPC will complete this project by December 31, 

2016. 

3 Boiler #5 is shutdown. 

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height increases should be tied to the natural gas fuel conversions. The stack height increase will 

be complete by December 31, 2016. 

As part ofthe control strategy, GPC will restrict public access to the levee located between 

GPC's property and the Mississippi River. GPC will post signs of warning on the north and 

south fence lines that intersect the levee. The signs will also state that loitering and fishing on the 

levee in the restricted access areas is prohibited. GPC security staff will conduct surveillance of 

the levee throughout the day and will document surveillance times and locations. The levee 

requirements are included in Attachment A to GPC's ACO and will be included in a permit to 

ensure ongoing implementation of the restricted access. 

In addition to the significant modifications GPC is undertaking as part of the control strategy, 

GPC is also voluntarily implementing a com truck queuing and idling policy. The policy is not 

submitted as part of the control strategy for the SIP revision, but will reduce PM2.s, NOx and 

S02, emissions and alleviate truck traffic congestion near the facility. The policy is designed to 

reduce overall com truck wait time which will result in lower PM2.s emissions from truck idling. 

Reductions in idling time will be achieved through scheduling and processing practices as 

described in the policy. The control strategy for GPC is made enforceable through Administrative Consent Order No. 

2014-AQ-A1, submitted as part oflowa's SIP revision. This ACO will become part ofthe SIP 

once EPA has granted final approval. This document will remain in place until Iowa issues 

permits for all the sources and emissions points in the SIP. Once the permits are issued, those 

documents will be incorporated into the SIP in a future SIP action and will also be federally 

enforceable. 

Full implementation of the control measures at GPC will reduce PM2.s emissions from GPC by 

an estimated 367.9 tons/year. See Table 3 for a summary of the emission reductions expected 

from the implementation of the control strategy. 

The complexity of the design, fabrication, and construction of the projects at GPC supports the 

phased implementation schedule, and although the full implementation of the GPC control 

strategy is not scheduled to be complete until December 31, 2016, EPA understands that GPC 

has begun and continues to implement the control strategy. Further, approval of the phased 

implementation schedule does not have a negative effect on air quality. As discussed in the air 

quality monitoring portion of the TSD, the 24-hour PM2.s design values have been steadily 

declining over the last three design value periods. The on-going implementation of controls 

pursuant to the control strategy will ensure that future design values stay below the 24-hour 

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agreements. The pqmary sources of PM2.s from UTC are from the removal of paint from rail 

tank cars, repair of rail tank cars, and application of paint through a spray system on rail tank 

cars. UTC is not a major source ofPM2.s, but is located near the Garfield School monitor. Iowa 

determined that UTC contributed to predicted violations of the PM2.s NAAQS. Therefore, Iowa 

included UTC in the control strategy. 

As part of the control strategy, UTC is installing new particulate controls on several emission 

points. It is also increasing stack heights at select locations and restricting operations of certain 

processes. Full implementation of control measures at UTC will reduce PM2.s emissions from 

UTC by an estimated 0.3 tons per year. The UTC control measures are made enforceable through 

state-issued air construction permits, which will be part of the SIP once EPA has granted final 

approval. All of the control measures at UTC have been implemented. 

3. MPW 

Muscatine Power & Water (MPW) is a municipal electric generating station located 

approximately 1.6 kilometers south and east of the Garfield School monitor. The primary sources 

ofPM2.s at MPW include emissions from three coal-fired boilers, Units 7, 8, and 9, and 

emissions from the associated handling and storage equipment. 

As part ofthe control strategy, MPW will conduct regular watering of road surfaces; pave an 

unpaved road and water road surfaces; remove a lime silo and mixing tank, 3 diesel engines, and 

wet fly ash truck loading; and implement operational restrictions. MPW will also reduce the 

capacity of its limestone hopper loading and handling systems; install a roofed enclosure with 

three sides for the limestone hopper; and reduce the size of the coal pile, limestone pile and 

synthetic gypsum pile. MPW is modifying its dust collection system for its coal reclaim and the 

coal crush feeders by reconfiguring the equipment and increasing the stack height. The MPW 

control measures are made enforceable through state-issued air construction permits, which will 

be part ofthe SIP once EPA has granted final approval. All of the control measures at MPW 

have been implemented. The full implementation of the control strategy at MPW is expected to 

reduce PM2.s emission from MPW by an estimated 0. 7 tons per year. 

4. Conclusion 

EPA is proposing to approve the control strategy and establish the attainment date pursuant to 

the SIP call to December 31, 2017, because this date is as expeditiously as practicable for the 

area to reach attainment. EPA is proposing this compliance date based upon the information in 

Iowa's SIP, our review of the supplemental information provided by GPC by email dated April 

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of Control Strategy 

Actual Emissions Reductions Estimated Percent 

Facility (tons/year)* (tons/year) Reduction 

GPC 537.6 367.9 68.4% 

MPW 58.3 0.7 1.2% 

UTLX 3.0 0.3 10.0% 

Total 598.9 368.9 61.6% 

* Based on average of 2007 and 2008 production data 

D. Contingency Measures 

In the SIP Call, EPA stated that it was reasonable to expect that the 98th percentile value of 24-

hour concentrations for the calendar year after the necessary controls were implemented should 

be at or below the 24-hour PM2.s standard (35 ug/m3). 76 FRat 41426. EPA stated that 

contingency measures will be triggered if that value is· above the 98th percentile value in the 

calendar year after the implementation of controls necessary for attainment or in any subsequent 

year. Id. EPA then stated that the SIP revision must contain an enforceable commitment to adopt 

and implement sufficient contingency measures, once triggered, in an expeditious and timely 

fashion that is comparable and analogous to the requirements for contingency measures in CAA 

section 175A(d). Id. 

EPA determined that the reference to CAA section 175A(d) was warranted because EPA made 

the SIP call to ensure that the area attains and then continues to maintain the PM2.s standard. 76 

FRat 41428. At the time of the SIP Call, Iowa did not comment on the proposed contingency 

measure trigger. Id. 

In Iowa's SIP revision, Iowa includes a phased approach to the contingency measures and 

triggers. Iowa stated it will use a violation of the 2015-2017 (or any subsequent) PM2.s design 

value measured from the Garfield School monitor to determine whether contingency measures 

should be implemented (first tier trigger). The contingency measures would then be implemented 

no later than 24 months as stated in the SIP Call. If a contingency measure is triggered, Iowa 

would then use the 98th percentile value for any subsequent calendar year following the 

implementation of contingency measures to determine the need for additional measures (second 

tier trigger). 

4 This information is included in the docket for this action. 

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Iowa stated in its submission that it proposed this two tier approach because Iowa believed the 

SIP Call trigger (98th percentile in the calendar year following implementation of controls) did 

not adequately consider the potential role of regional (non-local) events. Iowa reviewed the 

statewide historical 98th percentile PM2.s monitoring data for the past 10 years. Iowa's review 

showed that if the SIP Call trigger was used, many communities in eastern Iowa that are not 

adjacent to direct sources ofPM2.s and that are not currently designated as non-attainment for the 

24-hour PM2.s NAAQS, would have been designated non-attainment for the 24-hour PM2.s 

NAAQS due to regional PM2.s episodes. Iowa also found that the SIP Call trigger failed to 

account for the documented year-to-year variability of meteorological conditions. The annual 

variability of meteorological conditions is accounted for in the form of the 24-hour PM2.s 

standard, which uses a three-year average of 98th percentile values. 

EPA commented on this approach during the public comment period on Iowa's proposed SIP 

revision. Iowa stated that the two tier trigger approach allows for the triggering of contingency 

measures on the same time schedule that would have been applicable with a trigger based only 

on the 98th percentile value for the calendar year after complete implementation of the control 

strategy. 

Section 175A(d) contingency measures are required as part of SIPs to assure that a state will 

promptly correct any violation of the standard which occurs after the redesignation of the area as 

an attainment area. The contingency measures shall include a requirement that the state will 

implement all measures with respect to the control for the air pollutant concerned which were 

contained in the SIP for the area before redesignation of the area to attainment. In the SIP Call, 

EPA stated that it did not intend to imply that section 175A( d) is literally applicable to the 

Muscatine area, but rather provided that IDNR follow 175A(d)_as a guide for developing and 

implementing contingency measures. 76 FRat 41428. At the time of the SIP Call, EPA 

believed it was reasonable to expect the 98th percentile would be the appropriate trigger for 

implementing contingency measures. 76 FRat 41426. After reviewing Iowa's SIP revision and 

the associated contingency measures, EPA believes that the SIP revision meets the requirements 

ofthe SIP Call. Iowa has used Section 175A(d) as guidance in developing the contingency 

measures, as required by the SIP Call. The contingency measure trigger proposed by Iowa is 

also reasonable. The first contingency measure trigger using the design value to determine 

whether there is.a violation is consistent with the 2006 PM2.s NAAQS. The second contingency 

measure trigger using the 98th percentile value is consistent with EPA's SIP Call. Iowa will 

immediately implement the contingency measures as described below, upon reaching the first 

trigger. EPA has carefully reviewed the control strategy and the contingency measures 

proposed and agrees that the design value trigger for the contingency measures is reasonable, 

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at the Garfield School monitor, Iowa will require the submission of an emissions control 

program from the appropriate sources in the area. Iowa will determine which sources are 

required to submit an emissions control program based on the circumstances that triggered the 

exceedance. Iowa developed examples of potential contingency measures that may provide 

additional reductions in the event of an exceedance. These include the following: 

• evaluate and install additional control equipment, as needed; • eval.uate and implement changes in stack parameters and stack configurations to improve 

dispersion of emissions; 

• evaluate and implement additional operation and production restrictions; 

• evaluate and implement process changes to reduce PM2.s and PM2.s formation; 

• review operations and maintenance procedures to determine whether improvements can 

be made; 

• re-evaluate traffic flow patterns at facilities and vehicle miles traveled to determine 

whether idling time and congestion can be reduced; 

• re-evaluate material produce unloading, handling, and loading procedures and patters to 

determine whether improvements can be made; 

• re-evaluate facility best management practices associated with housekeeping including 

cleaning internal and external areas to minimize dust when the facility is receiving, 

transferring or loading out materials and product; 

• consider planting vegetation in specific areas to control dust flow patterns and fugitive 

emissions; and 

• identify and implement other improvements that may be necessary based on potential 

sources of particulate emissions. 

The contingency measures adoption and implementation schedule is as follows: 

T a e bl 4 C t" . . on m2ency M easures Ad op110n f an d I l mpl em en t a f IOn s c e u e h d l 

Activity Completion Date {T=trigger date) 

1) Evaluate circumstances of trigger; ID sources T+ 1 month 

2) Identify additional control measures T + 2 months 

3) Facility(s) submit emission control program T+4months 

4) Issue order or permits T + 6 months 

5) Facility(s) implement additional control Within T + 24 months 

measures 

The emissions control plan for any facility required to submit a plan would include the necessary 

supporting technical information, emissions calculations, construction permit applications, and 

air quality evaluation to make the additional control measure enforceable through the issuance of 

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hour PM2_s standard, based upon 2008-2010 data, and have shown violations of the standard in 

the past. EPA recognizes that the monitoring value for the 24-hour PM2.s NAAQS in Muscatine 

(for 2011-2013) is presently 28 Jlg/m3. However, as described by EPA in the 2011 SIP Call and 

by Iowa in the Muscatine PM2.s SIP, the Muscatine area monitoring values have demonstrated a 

trend of fluctuation. The SIP Call and Iowa's SIP revision are intended to bring permanent and 

enforceable emission reductions to the Muscatine. Therefore, the control strategy shall be 

implemented even if the area's monitoring values continue to remain below the level of the 

standard. 

It is also significant to note that strategies designed to reduce direct PM2.s emissions at GPC will 

also reduce emissions of other air pollutants. EPA's SIP Call did not require multi-pollutant 

emission reductions, but it is relevant that the state's control strategy for Muscatine is projected 

to have a beneficial impact on other pollutants of concern to the public. As provided by IDNR, 

the estimated percentage reduction of these air pollutants by 2017 are summarized in Table 5. 

Therefore, based on a review of the state submission, EPA recommends proposed approval of 

Iowa's SIP revision because it provides permanent and enforceable PM2.s emission reductions to 

the Muscatine area and improves the stringency of the Iowa SIP. 

Table 5. Estimated Co-Beneficial Emissions Reductions in Emissions from 2011 to 2017 at 

GPC* 

Pollutant Estimated Percentage Reduction 

Sulfur Dioxide (S02) 84 

Hazardous Air Pollutants (HAPs) 82** 

Volatile Organic Compounds (VOC) 48 

Nitrogen Oxides (NOx) 18 

Carbon Monoxide (CO) 13 

*These emission estimates were provided by GPC and have not been verified by DNR. 

**Reductions in acetaldehyde emissions are included in this percentage reduction. Seventy-one percent of the 

reduction is due to decreased Hydrogen Chloride (HCl) emissions from the coal-fired boilers. 

SOURCES USED 

Clean Air Act, Title I, Part A - Air Quality and Emissions Limitations 

http://www.epa. gov/air/caa/title1 .html 

Section 1 07, Air quality control regions 

Section 109, National ambient air quality standards 

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http://www.epa.gov/epacfr40/chapt-I.info/chi-toc.htm 

Subpart A, Air Emissions Reporting Requirements 

Subpart F, Procedural Requirements 

Subpart G, Control Strategy Subpart I, Review ofNew Sources and Modifications 

Subpart L, Legal Authority 

Appendix V to Part 51, Criteria for Determining the Completeness of Plan Submissions 

Appendix W to Part 51, Guideline on Air Quality Models 

40 CFR Part 52, Approval and Promulgation of Implementation Plans 

http://www .epa.gov/region07 /air/rules/iowa/ia toc.htm 

Subpart Q, Iowa 

US EPA On-line State Implementation Plan Processing Manual 

http://icode.pes.com/sipmanl 

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