March 1 5 , 201 3 Clean Air Act Section 110(l) Demonstration t o Support Amendments to 10 CSR 10
- 6.390, Control of NOx Emissions From L arge Stationary Internal Combustion Engines **Background** The U.S. Environmental Protection Agency (EPA) f inalized Phase II of the Nitrogen (NOx) State Implementation Plan (SIP) Call on April 21, 2004. Phase II required the E astern one - third of Missouri to p articipate in the NOx SIP Call and included a provision related to source categories of internal combustion (I C) engines
. The I C engine provision established a requirement to decrease emissions from stationary diesel and dual fuel engines by ninety percent (90 %)
. The NOx SIP Call required each state in the control region to develop and submit a SIP that contained adequate provision s prohibiting its sources from emitting air pollutants in amounts that w ould contribute significantly to nonattainment, or interfere with maintenance, in one or more downwind states for the 1
- hour ozone and 1997 8
- hour ozone National Ambient Air Quality Standards (NAAQS)
. The overall amount of emission reduction s required b y each state was based on the sum o f the applicable utility , non - utility boiler, cement kiln, and stationary I C engine emissions as follows: (a) 0.15 pounds per million British Th ermal Units for electric generating units (EGUs); (b) 82 percent emission reductions for large natural gas
- fired stationary I C engines; (c) 90 percent emission reductions for diesel and dual fuel stationary I C engines; (d) 60 percent emission reductions for non
- EGU bo ilers and turbines; and (e) 30 percent emission reductions for cement manufacturing facilities. New rule 10 CSR 10
- 6.390, Control of NOx Emissions From Large Stationary Internal Combustion Engines , was developed to address the I C engine provisions of the NOx SIP Call and originally

became effective October 30, 2005. An amendment to the rule was adopted in 2010 to include emission rate limitations for both large stationary diesel and dual fuel IC engines which were no t included in the original rule
. At the same time, a NOx twenty
- five (25) ton exemption was added b ecause meeting the emission limit would be very costly per ton of NOx removed , by

far exceeding the federal study findings for cost feasibility of two
- thousand ($2,000) per ton
. A total of six ( 6 ) f

acilities with twenty - eight (2 8 ) units were originall y affected by the amendments to 10 CSR 10
- 6.390. They are as follows: City

of Campbell with one (1) engine; City of Farmington with fourteen (14) engines; City of Jackson with three (3) engines; City o f Kahoka with three (3) engines; City of Owensville with four (4) engines; and Poplar Bluff with three (3) engines. However , IC engine number 8 at Campbell City has since been retired and is no longer in service. As described in greater detail below, the se facilities all have very low NOx emissions and qualify

for the twenty
- five (25) ton exemption in the rule. The affected facilities are located in an area defined by the federal Phase II NOx SIP Call as the E astern one - third of the state of Missouri , se e Attachment A.**EPA Comments and Purpose** 

During the rule amendment public comment period, EPA commented that based on Section 110(l) of the Clean Air Act (CAA) an y exemption to the rule must be accompanied by an anal ys is which demonstrates that the exemp tion will not adversely impact air quality . Section 110(l) of the CAA specifies that state implementation plan revision s must not interfere with an y applicable requirement concerning attainment and reasonable further progress, or any other applicable requ irement of this Act. EPA also commented that Missouri would need to show that the exemption will not affect the state’s ability to meet the NOx SIP Call budget obligations. The purpose of this document is to address EPA’s comments by demonstrat ing this rulemaking does not impact Missouri ’s ability to meet NOx budget obligations under the NOx SIP Call and does not adversely

impact air quality
. For the air quality demonstration, this document focuses on the ozone and nitrogen dioxide (NO 2 ) NAAQS, which are the two (2) NAAQS potentially impacted b y NOx emissions from large IC engines. **NOx Budget Demonstration**  On August 1, 2005 the Missouri SIP for the NOx SIP Call was submitted to EPA , and it was approved b y EPA on August 15, 2006. The approved SIP revis ion established a NOx emissions budget of twenty - thousand nine
- hundred eighty - seven ( 20,987 ) tons during the ozone season, defined as May

1 through September 30. The budget serves as a cap on overall ozone season NOx emissions from affected utilities, non
- utility boilers, cement kilns, and I C engines beginning in 2007. Please note IC engines were not included in the original Missouri budget for the NOx SIP Call. T able 1 below is a summary of each segment’s budget and ozone season NOx emissions from 2007
- 2 011. The table shows that Mis souri has been below the ozone season budget each ye ar based on total ozone season NOx emissions from the utility , non - utility boiler, and cement kiln budget segments of the NOx SIP Call. **Table 1 . Missouri NOx SIP Call Budge**  **t and 2007 -**  **2011 Ozone Season NOx Emissions by Source Type**  Ozone Season (tons NOx) Emission Reduction Category 1 Yearly

O zone S eason Budget 2011

Actual Emissions 2010

Actual Emissions 2009

Actual Emissions 2008

Actual Emissions 2007

Actual Emissions 2 Util ity 13,400 14,804 13,380 12,336 12,854 12,961 2Non
- Utility boiler 104 0 0 0 0 2.2 3 Cement Kiln 7,483 2,266 2,015 1,092 4,797 5,339 Total 20,987 17,070 15,395 13,430 17,651 18,300 1 NOx SIP Call Budget Demonstration for Missouri. 2 20 11 , 2010 , 2009, 2008, 2007 Ozone Season CAMD reported emissions. 3 2011, 2010, 2009, 2008, 2007 reported annual MoEI S emissions multiplied by ozone season day s per year over 365 day s .As shown in Table 1, the projected 2007 utility ozone season NOx emissions budg et of thirteen
thousand f

our - hundred (13,400) tons was estimated in the NOx SIP Call
. Since 2005, two (2) selective catal yt ic reduction with overfire air, one (1) low NOx burner with overfire air and two (2) overfire air NOx control units have been instal l ed at utilities located in the E astern one - third of the state of Missouri. Although 2011 utility emissions are over the utility portion of budget due to additional NOx emission allowances being purchased in the Eastern one
- third of the state, buying and selling allowances is acceptable under the NOx SIP Call program , and the overall emissions from all segments are below the ozone season budget for 2011. Utility boilers included in the NOx SIP Call budget are subject to state rule 10 CSR 10
- 6.360, Control of NOx Emissions From Electric Generating Units and Non
- Electric Generating Boilers. The 2007 budgeted ozone season emissions for non
- utility boilers were one
- hundred four (104) tons NOx, and as shown in Table 1 , the non
- utility boilers 2008 and after oz one season emissions were zero (0) tons
. The three (3) non
- utility units that were included in the NOx SIP Call budget were Anheuser
- Busch, Inc., unit 6, and Ashley Street Station units 5 and 6. InEPA’s Clean Air Markets Division (CAMD) database Anheuse r - Busch, Inc. unit 6 (utility identification number 10430 ) was retired October 10, 2009, and the Ashley Street Station (utility

identification number 880094) units 5 and 6 ( EU0060 and EU0070 i n CAMD ) retired October 29, 2008. Non
- utility boilers included in the NOx SIP Call budget are subject to state rule 10 CSR 10
- 6.360, Control of NOx Emissions From Electric Generating Units and Non
- Electric Generating Boilers. As shown in Table 1, c ement kiln emissions have substantially decreased and are well below the budget for this sector
. InMarch of 20 10 the Holcim
- Clarksville facility signed an Idle Status Settlement Agreement and will not operate in the future. One new cement kiln, Holcim
- Le e Island commenced operation in 2009 and is located in the E astern on e - third of Missouri. This plant must meet Best Available Control Technology (BACT) NOx requirements for cement kilns. The cement kilns included in the NOx SIP Call budget are all subject to 10 CSR 10
- 6.380, Control of NOx Emission s From Portland Cement P lants and are all meeting the requirements of the rule
. Table 2 shows the actual annual emissions of I C engines that are subject to 10 CSR 10
- 6.390, Control of NOx Emissions From Large Stationary Internal Combustion Engines for 2011, 2010, 2009, 2008, and 2007. The table shows that these facilities are consistently very low NOx emitters. T he total annual potential to emit for these units combined is six
- hundred seventy - five (675) tons of NOx. If the total I C engine potential to emit six
- hundred seventy
- five (675) tons NOx were added to the total emissions from all source categories in Table 1, Missouri would still be below its NOx SIP Call Budget. This is a very conservative assessment of the I C engines’ impacts on the NOx SIP Call Budget because the po tential to emit is significantly higher than emissions reflecting actual operations and this annual value, not just ozone season. **Table 2 .**  **Actual Annual NOx Emissions from 2007 -**  **2011 for IC Engines Exempted from 10 CSR 10**  **- 6.390**  Yearl y Actual NOx Emission s (tons)Plant Name Number of Units Affected 2011 2010 2009 2008 2007 Campbell City 1 N/A N/A 0.0 0.2 0.4 Farmington 14 1.2 1.0 2.1 0.7 2.1 Jackson 3 0.0 0.0 0.0 0.0 0.0 Kahoka 3 0.1 0.1 0.1 2.9 0.0 Owensville 4 0.0 2.5 0.0 0.0 0.0 Poplar Bluff 3 0. 9 1
. 1 1.1 2
. 2 9
. 5 Total 2.2 4.9 3.4 6.1 12.1 **Air Quality Demonstration** This portion of the technical support document addresses potential impacts of the affected IC engines on the ozone and NO 2 NAAQS
. 1. Ozone Season NAAQS In March 2008, EPA establ ished the current ozone NAAQS of seventy
- five (75) parts per billion (ppb) measured over an 8
- hour time period. Attachment B shows the locations of the ozone monitors in the Eastern one
- third of the state. Six (6) of the monitors are located in the St. L ouis area, currently

the only ozone nonattainment area in the state (nonattainment for both the 1997 and 2008 ozone NAAQS) , and two (2) ozone monitors are located in Ste. Genevieve and Perry Counties. As discussed in detail in the technical support document for the department’s original 2008 ozone NAAQS boundary recommendation (submitted to EPA in March 2009), extensive meteorological analy sis was conducted to determine emission source regions with the highest probability

of impacting these ozone monitor s. A summary of the results is as follows:  T he highest ozone concentrations in the St. L ouis area occur when there is a high pressure center over the eastern United States (southerly components to flow direction are predominant) with reduced wind speeds or stagnant conditions.  Emissions from within the metropol itan St. L ouis area have the strongest likelihood of contribution to the vast majority of the sites in the ozone network.  C ontributions to elevated ozone concentrations at the Farrar ozone monitor in Perry County are due to transport primarily from areas east and south of the monitor.  The Bonne Terre ozone monitor in Ste. Genevieve County has the highest concentrations when the winds have a northerl y or easterl y component, i.e., it tends to be impacted the most by emissions from the St. L ouis area
.  St. Francois County

emission sources do not have a frequent impact on the Bonne Terre monitor. Also in the department’s boundary recommendation for the 2008 ozone NAAQS, it was determined that emission sources in St. Francois County were not significant contributors to ozone in the St. L ouis area and therefore was not recommended as part of the nonattainment area. EPA approved the department’s recommendation for the St. L ouis nonattainment area boundary without modification on May 21, 2012 (77 FR 30088).This demonstration centers on the Farmington power plant in St. Francois County
. Of the five

(5) small sources affected by the 10 CSR 10
- 6.390 NOx exemption (excluding Campbell City which is retired) , the Farmington plant has the greatest potential for impacting the ozone monitors. This is because it has the highest overall NOx emissions and greatest number of affected IC engine units (14 units) as shown in Table 2 . It is also located south and adja cent to the St. L ouis nonattainment area , which is generally in the path of the predominant wind direction on ty

pical high ozone day s , and it is near the Bonne Terre monitor in Ste. Genevieve County
. As detailed in the emissions inventory for point, are a, and mobile sources in Attachment C , 2008 NOx emissions from all sources in St. Francois County were 8.76 tons per ozone season day
. The Farmington power plant’s 2008 NOx emissions were 0.0018 tons per ozone season day , or 0.021% of the county’s total d aily ozone season NOx , which is negligible compared to the overall county dail y emissions . Because total St. Francois County emissions do not have a meaningful imp act on St. L ouis ozone monitors as established in the boundary designation process and NOx e missions from the Farmington power plant are a small fractio n of the total county emissions , it can be concluded that the Farmington power plant has an insignificant impact on the St. L ouis area ozone monitors. T he Farmington power plant is expected to have minimal contribution to the Farrar and Bonne Terre ozone monitors as well. As determined in the boundary designation process, St. Francois County emissions do not have a frequent impact on the Bonne Terre ozone monitor . Since Farmington power plant is such a small percentage of the total county ’s NOx emissions, it likely does not have a significant impact on the Bonne Terre monitor. Furthermore, with the Farrar monitor’s impacts primarily resulting from transport ed pollutants from the east and south, the Farmington power plant is unlikely to contribute to elevated ozone levels measured at that monitor. If the Farmington plant doesn’t have an impact on the St. L ouis and surrounding ozone monitors, it is highl y unlikel y that the other small sources ex empted by this rule would have an y impact s . The Owensville power plant in Gasconade County has very low NOx emissions as shown in Table 2 and is located west of the St. L ouis nonattainment area, which is not a predominant wind direction on high ozone day s . The Jackson, Kahoka and Poplar Bluff power plants in Cape Girardeau, Clark and Butler Counties, respectivel y, are all very small NOx sources and are located too far away

from any of the ozone monitors to have any measurable impact. 2. NO 2 NAAQS In February

2010, EPA set a new NO 2 NAAQS of one hundred (100) ppb measured over one ( 1 ) hour, while retaining the annual NO 2 NAAQS of fifty
- three (53) ppb
. Attachment B shows the location of the only

NO 2 monitor in the Eastern one
- third of the state. It is in St. L ouis City
. Missouri does not have any nonattainment areas for the 1
- hour NO 2 NAAQS. In the preamble to the final 2010 NO 2 NAAQS, EP A acknowledges that the highest concentrations of NO 2 drop off quickl y with distance and the impacts of NOx em issions tend to be localized:Research suggests that the concentrations of on

- road mobile source pollutants such as

NO X , carbon monoxide (CO), directly emitted air toxics, and certain size distributions of particulate matter (PM), such as ultrafine PM, ty pically display peak concentrations on or immediately adjacent to roads. This situation typically produces a gradient in pollutant concentrations, with concentrations decreasing with increasing distance from the road, and concentrations generally decreasing to near area - wide ambient levels, or typical upwind urban background levels, within a few hundred meters downwind. (75 FR 6479, February 9, 2010)

. In addition, a scientific paper titled “Modeling the chemical evolution of nitrogen oxides near roadway s” (Wang, Yan Jason, Denbley ker, Allison, McDonald
- Buller, Elena, Allen, David, and Zhang, K. Max) provides further evidence supporting NO 2 dissipation rates from roadway s. Based on this assessment that NO 2 concentrations dissipate quickly with distance from the source, often returning to area background levels within a few hundred meters, the two (2) sources closes t to the St. Louis NO 2 monitor are likely too far away

to have a significant impact. The Farmington and Owensville power plants are located about sixty ( 60 ) and seventy ( 70 ) miles from the only

current NO 2 monitor in the St. L ouis area
. All other sources exempted by 10 CSR 10
- 6.390 are located even farther away and are much less likely

to have any

measurable impact. Historical data from an NO 2 mo nitor located at Bonne Terre that was shut down in September 2010 provides evidence of the Farmington power plant’s minimal impact on an NO 2 monitor located much closer. The Bonne Terre NO 2 monitor was approximately eight (8) miles due north of the Farmin gton plant. As shown in the data summaries for this monitor from 1996 through the third quarter of 2010 on the department’s website (http://dnr.mo.gov/env/esp/aqm/bonne
terre.htm ), the annual averages and annual 1
- hour daily maximum values are well below both the annual and 1
- hour NO 2 NAAQS. It should be noted that the annual 1
- hour daily maximum values are not directl y comparable to the current 1
- hour NO 2 NAAQS, which is based on a 3
- ye ar aver age of the 98 th percentile (or 8 th highest) of the yearly distribution of 1
- hour dail y maximum concentrations. However, since the 1 st high 1
- hour daily maximum value is greater than the 8 th high value, this is a conservative assessment. This historical d ata from a much closer monitor confirms that the Farmington power plant likely has a minimal contribution to the St. Louis NO 2 monitor that is sixty (60) miles away
. Another consideration in determining the impacts of a particular source on the NO 2 NAAQS is how it would be modeled to show compliance with the 1
- hour standard. A March 1, 2011 memorandum from Tyler Fox, EPA, title d “Additional Clarification Regarding Application of Appendix W Modeling Guidance for the 1
- hour NO 2 National Ambient Air Quality Standard” describes the treatment of intermittent emissions and their sources in conducting modeling determinations for the 2010 NO 2 NAAQS. This guidance exempts intermittent sources from modeling analy ses and indicates that modeling analy ses should focu s on emission sources that are continuous over a period of time or frequent enough to significantl y contribute to the annual distribution of daily

1
- hour NO 2 contributions. Campbell City (utility identification number 2903) , Farmington (utility identification number 6205) , Jackson (utility identification number 9603) , Kahoka (utility

identification number 9973) , Ow en sville (utility identificationnumber14272) , and Poplar Bluff (utility identification number 15229) IC engines are classified through the Ene rgy

Information Administration’s ( EIA’s ) 860 repo rt as standby /backup engines or operating engines. Each of these engines is connected to the electric grid in order to be dispatched for power. These engines are dispatched mainly during times of high demand which can fluctuate as summer temperatures may vary on a week to week or day by day basis. The Department of Energy

( DOE ) definition of a standby generator “involves use of generators during times of high demand on utilities to avoid extra peak
- demand charges , ” and the definition of an operating generator means “in service (commercial operation) and producing some electricity. ” The standb y generator definition also “ Includes peaking units that are run on an as needed (intermittent or seasonal) basis .” From this classification, the standby /backup engines would be considered intermittent and excluded from any modeling anal ys is of a source’s impacts on the NO 2 NAAQS. Because of their low average dail y NOx emissions , distance, and intermittent use , the Farmington and Owensville power plants are not expected to have a significant impact on the St. Louis NO 2 monitor and the other power plants exempted from 10 CSR 10
- 6.390 would have even less of an impact. **Conclusion** Th is document demonstrates that the recent revision of 10 CSR 10
- 6.390 to exempt five (5) small NOx sources will not impact Missouri’s ability to meet NOx budget obligations under the NOx SIP Call and does not adversel y impact air quality
. Even considering the maximum potential to emit from the se small sources, an extremely conservative level of emissions, overall emissions are still well below Missouri’s NOx SIP Call budget . Based on the magnitude of NOx emissions, distance to the ozone and NO 2 monitors , predominant weather conditions on high ozone day s, and intermittent use of these engines, the small NOx sources exempted from this rule are likely

to have an insignificant impact on the ozone and NO 2 NAAQS.