# UTAH PMIO Maintenance Provisions for Salt Lake County Section IX.A.10

Adopted by the Air Quality Board July 6, 2005

### IX.A.IO.a

IX.A.10.b

IX.A.lO.c Adoptedby tlteAir Quality BoardJuly 6. 2005


## Table ofContents Introduction 1 (1) 

### ThePM1oSIP 2 

### (2) Supplemental History ofSIP Approval

- PM IO 

### 2 (3) 

### Attainment ofthe PM 10 

### Standard and ReasonableFurther Progress 2 

### Pre-requisites to Area Redesignation 3 (1) 

### The Area Has Attained the PMIO 

### NAAQS 4 

### (a) Ambient Air Quality Data (Monitoring) 4 

### (b) PM 10Monitoring Network 7 

### (c) Modeling Element 9 (d) EPA Acknowledgement 10 (2) 

### Fully Approved Attainment Plan for PMIO 10 (3) 

### Improvements in Air Quality Due to Reductions inEmissions 10 (a) 

### Improvement in Air Quality 

### 10 (b) 

### Reduction in Elllissions 18 (4) 

### State has Met Requirements Under Section 110

### and Part D 20 (5) 

### Maintenance Plan for PMIO 

### Areas 20 

### Maintenance Plan 21 (1) 

### Demonstration ofMaintenance

- Modeling Analysis 21 

### (a) Meteorological data 22 

### (b) Emissions Data 24 (c) 

### Modeling Results 24 (d) 

### Annual Standard 27 (e) 

### Magna 

### 28 (2) Attainment Inventory 28 (3) 

### Emissions Limitations 30 (4) 

### Emission Reduction Credits 31 (5) 

### Additional Controls for Future Years 31 (6) 

### Mobile Source Budget for Purposes ofConformity 31 

### (a) Salt Lake County Mobile Source PMlO 

### Emissions Budgets 32 (b) 

### Net Effect to Maintenance Demonstration 33 (7) 

### Nonattainment Requirements Applicable Pending Plan Approval 34 

### (8) Revise in Eight years 35 (9) Veritication ofContinued Maintenance 35 (J

### 0) Contingency Measures 35

Section IX.A.IO. page i_ __ _ Adoptedby the Air Quality BoardJuly 6,2005

This Federal Register notice (66 FR 32752) and the milestone report from September 29, 1995 have been included in the TSD. Furthermore, since these control measures are incorporated into the Utah SIP, the emission reductions that resulted are consistent with the notion ofpermanent and enforceable improvements in airquality. Taken together, the trends in ambient airquality illustrated in the preceding paragraph, along with the continued implementation ofthe nonattainment SIP for the Salt Lake County nonattainment area, provide a reliable indication that these improvements in air quality reflect the application ofpermanent steps to improve the airquality in the region, rather thanjust temporary economic or meteorological changes. 

### (4) State has

### Met Requirements UnderSection 110 and PartD eM 107(d)(3)(E)(v)· The State containing such area has met all requiremenrs applicable 10 the area undersection 110andpartD. Section 110ofthe CAA deals with thebroad scope ofstate implementation plans and the capacity ofthe resIJe(:tive state agency toeffectively administer such a plan. Sections I through VIII ofUtah's SIPcontain information relevant to these criteria. 

### Part D deals specifically with plan requirements for nonattainment areas, and includes the requirements for a maintenance plan in Section 175A. Utah currently has an approved SIP that meets therequirements of section 110(aX2) ofthe Federal Clean Air Act. Many ofthese elements have been in placefor several decades. In the March 9, 2001 approval ofUtah's Ogden City MaintenancePlan for Carbon Monoxide, EPA stated: On August IS, 1984, we approved revisions to Utah's SIP as meeting the requirements ofsection 11O(a)(2) ofthe CAA (see 45 FR 32575). Although section 110ofthe CAA was amended in 1990, most ofthe changes were not substantial. Thus, we have detenninedthat the SIPrevisions approved in 1984 continueto satisfy the requirements ofsection 110(a)(2). Forfurther detail, see 45 FR 32575 dated August 15. 1984 (Volume49, No. 159)or 66 FR 14079 dated March 9, 2001 (Volume 66, No. 47.) Part D ofthe Clean Air Act addresses "Plan Requirements for Nonattainment Areas", One ofthe pre-conditions for a maintenance plan is a fully approved attainment plan for the area. This is also discussed in section IX.A.1O.b(2). For Salt Lake County, the Part D requirements for PMIQ were addressed in an attainment SIP approved by EPA on July 8,1994 (59 

### FR 35036). 

### (5) Maintenance Plan for PM10 

### Areas As stated in the Act, an area may not request redesignation to attainment without first submitting, and then receiving EPA approval of, a maintenance plan. The plan is basically a quantitative showing that the area will continue to attain the NAAQS for an additional 10 years (from EPA approval), accompanied by sufficient assurance that the tenns ofthe numeric demonstration will 

### be administered by the State and by the EPA in an oversight capacity. The maintenance plan is the central criterion for redesignation. It is contained in the following subsection.

Section IX.A.IO, page 20



# ---_

.. 

### ..-..-.. ..... .. ..Adoptedby theAir Quality BoardJuly 6. 2005 

# IX.A.I0.c Maintenance Plan
CM 107(d)(3)(E)(iv)

. The Administrator hasJully approveda maintenanceplanJorthe area as meeting the requirements of section 175A. An approved maintenance plan is one ofseveral criteria necessary for area redesignation as outlined in CAA 107(d)(3)(E). The maintenance plan itself, as described in Section 175A ofthe CAA and further addressed in EPA guidance (Procedures for Processing Requests to Redesignate Areas to Attainment. John Calcagni to Regional Air Directors, September4, 1992; orfor the purpose ofthis docurrimt. simply "Calcagni"). has its own list ofrequired elements. The following table is presented to summarize these requirements. Each will then be addressed in turn. 

### TableIX.A.32 

### Requirements ofa Maintenance Plan Addressed 

### Cate20ry Requirement Reference in Section Maintenance Provide for maintenance ofthe relevant CAA: Sec IXAI0.c(1) demonstration NAAQS in the area for at least 10years after 175A(a) redesignation. Revise in 8 The State must submit an additional revision to CAA: Sec IX.A.I0.c(8) Years the plan. 8 years after redesignation, showing 175A(b) an additional 10years ofmaintenance. Continued The Clean Air Act requires continued CAA: Sec IX.A.1O.c(7) Implementation implementation ofthe nonattainment area 175A(c), of control strategy unless such measures are CAASec Nonattainment shown to be unnecessary for maintenance or 110(1), Area Control are replaced with measures that achieve Calcagni Strategy equivalent reductions. memo Contingency Areas seeking redesignation from CAA: Sec IX.A.lO.c( 10) Measures nonattainment to attainment are required to 175A(d) develop contingency measures that include State commitments to implement additional control measures in response to future violations ofthe NAAQS.

. Verification of The maintenanceplan must indicate how the Calcagni IX.A.1O.c(9) Continued State will track the progress ofthe maintenance memo Maintenance ]plan.

0_0 

# - (1) 

### Demonstration ofMaintenance

- Modeling

### Analysis CAA 175A(a)

- Each State which submits a request undersection l07(d)for redesignation of a nonattainment area as an area which has attainedthe NAAQS shall also submit a revision afthe applicable implementationplan toprovidefor maintenance of the NAAQS for at least 

### J 0years after the redesignation. Theplan shall contain such additional measures, 

### if any. as may be required to ensure such maintenance. The maintenance demonstration is discussed in EPA guidance (Calcagni) as one ofthe core provisions that should be considered 

### by states for inclusion in a maintenance plan. According to Calcagni, a State may generally demonstrate maintenance ofthe NAAQS by either showing that future emissions ofa poHutant or its precursors will not exceed the level ofthe attainment inventory (discussed below) or by modeling to show that the future mix ofsources and
Section IX.A.lO, page 21AdopledbyIhe Air Quality BoardJuly 6,2005

emission rates will not cause a violation ofthe NAAQS. Utah has elected to make its demonstration based On air quality modeling. The guidance goes on to say that, in cases where a nonattainment SIP was based on air quality modeling, the maintenance plan should be based upon the same level ofmodeling used before. Furthennore, it says, such modeling should be consistent with currentEPA modeling guidance. The existing PM IO nonattainment SlP demonstrations for both Salt Lake and Utah Counties were based on a statistical modeling approach called chemical mass balance (CMB). This is a receptor based model that does not directly factor meteorology or dispersion characteristics into its predictions. Furthermore, CMB is limited in its treatment ofsecondary aerosol formation, which has historically accounted for between 65% and 85% ofthe overall PM 10 collected at the monitoring stations. While the success ofthese nonattainment SIPs is more or less an endorsement ofthe CMB modeling upon which they were founded, EPAfelt that any subsequent demonstration ofmaintenance should rely instead on a model that is more comprehensive in its assumptions. 

### In consultation with EPA Region VIII. DAQ decided to base the new Maintenance Plan upon a grid-based aerosol model called UAM-AERO. This model is 

### an extension ofthe widely used photochemical model, the Urban Airshed Model (UAM) Version 

### IV, which has been adapted to treat aerosol processes. DAQ established a UAM-AERO modeling domain that included each of Utah's three PMIO nonattainment areas. This single comprehensive modeling analysis serves as the basis for the maintenance demonstration for each area. The model was applied to address elevated 24-hour concentrations ofPMIO along the Wasatch Front (WF). These develop during winter-time episodes ofregional scale high pressure and associated valley temperature inversions. The inversions promote the accumulation ofPMIO and PM IO precursor gases that lead to significant secondary aerosol formation. Before the nonattainment SlPs were implemented, these ambient values oftenexceeded the 24-hour health standard for PM 10• In this analysis. DAQ has employed UAM-AERO to evaluate the airshed under worst case winter-time inversion conditions. In order to do so, the model considers two historical episodes: 1) January 1-10,2001 and 2) February 1-8,2002. Episode selection was based on criteria that included meteorology, observed PM IO concentrations, and data availability. Further discussion concerning episode selection can be found in Section 

### 2 ofthe modeling portion ofthe technical support document (TSD). Despite numerous severe inversion episodes during the past decade. PM lO concentrations have not been sufficient to cause a violation ofthe NAAQS. Consequently, the two selected episodes do not represent NAAQS violations, but do capture elevated

### PM 10 concentrations, worst-case meteorology. and current emission levels. Therefore, by modeling these episodes and projecting emissions into future years, the analysis should accurately reflect the ability ofthe nonattainment areas to maintain the PM IO NAAQs over the next 10 years. The DAQ modeling analysis requires two main inputs: meteorological data and emissions data. The applications ofthese inputs are discussed below. (a) Meteorological data Recent UDAQ meteorological modeling projects using advanced "state ofthe science" prognostic meteorological models have proven unsuccessful in simulating highly variable Wasatch Front meteorology during inversion conditiOnS. These problems led UDAQ to choose a diagnostic Section IX.A.lO. page 22Adoptedby theAir Quality Board July 6, 2005 meteorological model called the Diagnostic Wind Model (DWM) model for the January 200 1and February 2002 episodes to avert many ofthe past modeling problems. The DWM assimilates actual observations ofwind speed and direction todiagnose and construct a consistent wind field. UDAQ embarked on a 4-phase modeling approach in order to develop the mostrealistic wind fields possible. Each phase ofthe 4-phase modeling approach utilized unique combinations of observed meteorological data for each analysis. Each ofthe4 phases is described below: Phase 1 The DWM model was run utilizing 60-100 surface observing stations, two radiosondes, and two SODARs perday. The surface station data was taken from the University ofUtah MESOWEST database and included a wide variety of station types. Phase 

### 1 ofmodeling utilized only surface stations with an elevation of5,500ft or lower. The National Weather Service SaltLake City radiosonde data was used along with two DAQ SODARunits operated in Utah and SaltLake valleys. It was thought that the multitude ofavailable data would allow DWMtoproduce representative wind fields. UAM-AEROresults showed modeled PM IO values that were only 40-50% ofthe observed values. Model outputevaluation showed thatPMIO was being advected out ofthe SaltLake Valley (SLV) and the model domain tothe SE. Afternoon up-valley NW winds moved PM10 into the mountains to the SE ofthe SLV. At night, winds became light and variable at most surface stations and asa result were unable to return the PM 10 backto the SLV. Additionally, DAQ's hypothesized benefit ofhaving a multitude of surface stations actually induced unrealistic vertical motions due to surface convergence ofwidely varying wind directions. Phase 2 The failings ofphase I encouraged DAQ to be more selective ofthe surface stations used in DWM. First, the Salt Lake Valley SODAR was discarded due to observations that were incongruent with the Utah Valley SODAR and the Salt Lake City radiosonde. Second, DAQ selected only the DAQ operated surface stations. These surface stations are situated in strategic locations across the Wasatch Front. 11 DAQ stations were used. The phase 2 hypothesis was that the more selective set ofsurface stations might produce a wind field with less convergence and resultant vertical motions. DAQ found that the phase 2 wind 

### fierds produce periods ofdaytime 'N'W winds that advected pollutants out ofthe SLY. The noctumal and morning winds were light and variable and were unable toretum the pollutants to the SLY. Most ofthe observations within the SLY show a trend ofdaytime up-valley flow and nighttime weak variable flow. 

### In reality, the daytime flown recirculates within the boundaries ofthe inversion but in UAM-AERO the continuous grid network cannot retain the flow within the open sided grid cells ofthe SLY. Phase 3 Phase 2results showed transport ofPM 10 out ofthe SLY. Model evaluation clearly showed a direct link with the observation wind direction and speeds. Phase 3 tested the possibility that a single station located in SLY might produce a wind field that has a more even distribution of wind direction and speeds. In other words. is there a station in SLY that is representative ofthe vaIley but where daytime winds and nighttime winds balance each other? If so, developing a wind field from a single station may reduce advection out ofthe SLV.

Section IX.A.lO. page 23Adoptedby theAir Quality BoardJuly 

### 6. 2005
Three separate wind fields were developed in phase 3. These wind fields utilized the centrally located and well sited DAQ Hawthorne and West Valley monitors as wen as another well sited but southeasterly located DAQ Cottonwood station. The results ofphase 3 modeling again showed advection out ofthe SLY and the domain. Stronger daytime 

### NW winds compared to nighttime light and variable winds again forced the loss ofPM 10. Phase 

### 4 Phases 

### 1-3 clearly demonstrated the inability ofthe DWM model to accurately represent the conceptual understanding ofinversion conditions. The model deficiencies arise from the model grid-eell structure. The model grid cells are continuous and are unable to "trap" orcontain air within an inversion layer. Thereal wind observations in the SLY do have advective properties that would allow the pollutants to move beyond the boundaries ofthe SLV undernon-inversion conditions. However, under inversion conditions the advective properties ofthe real wind observations are negated by a forced recirculation of

### air within the inversion layer by the containing boundaries ofthe inversion. In phase 4, a purely idealized flow was created in the attempt to retain pollutants in the SLV. A bimodal wind direction field was created using an afternoon NW wind (330) and an evening, night, and morning SE wind (140). These directions correspond todaytime up-valley flow and nighttime down-valley flow. Wind speeds were chosen sothat advection was limited to within the boundaries ofthe SLV. This wind field, while idealized, fits the conceptual understanding of inversion conditions. Phase

### 4 modeling retains PMIO within the SLY and DAM-AERO PMJO results show excellent agreement with the observations. 

### (b) Emissions Data Area, point, and mobile emissions inventories were compiled for all sources within the modeling domain. Inventories included primary PM IO, sulfur dioxide (S02), oxides ofnitrogen (NO

### x), carbon monoxide (CO), and volatile organic compounds (YOC). In addition, an ammonia (NH3) inventory was estimated for area and mobile sources. Estimates ofbiogenic emissions were not included in the analysis because the episodes occurred in January and February when biogenic emissions are negligible. Other seasonal adjustments were also made to the inventory (adjustments are described in the modeling portion ofthe TSD). Base-year and projection inventories are also described in more detail in the TSD. Emission inventories are processed and spatially placed in the modeling domain by the Sparse Matrix OperatorKernel Emission (SMOKE) modeling system. SMOKE was developed by EPA for integration into the Models-3 Air Quality Modeling System and has been used in many air quality studies. Toensure that the model represents actual emissions during each model episode day, SMOKE uses source specific Source Classification Codes to chemically speciale and temporally allocate emissions. In addition, SMOKEuses other emission characteristics, such as stack height. exit velocity, and plume temperature to place emissions in the correct vertical layer ofDAM-AERO. Mobile and other area source emissions are treated as ground level emissions and input into the lowest model layer. (c) Modeling Results Projection year modeling was completed for the years 

### 2005,2008,2011,2014,2015, and 

### 2017. EPA's most current modeling guidance recommends that model predictions be used in a relative sense rather than an absolute sense. Applying the model this way is doneby calculating a "relative reduction factor" (RRF) for grid cells that are co-located with a PMIO monitor. RRF Section IX.A.lO. page 24Adoptedby theAir Quality BoardJuly 6, 2005


### values were computed for each day ofthe base-case modeling years (January 2001and February 2002) and subsequently applied to the future year predictions. The technique for creating the individual RRF is described in section 7 ofthe modeling TSD. 

### Results demonstrated that modeled PM 10 

### concentrations are highest in 2005. From there they decline until reaching a minimum value in 2011 or 2014, and then increase again through 2017. No PM 10

### values greaterthan 150 uglm3 were modeled for any ambientair 

### using eitherepisode. Ambient air means anywhere that would be 

### accessible tothe general public. There were two grid cells which showed predicted concentrations in excess of 150 uglm3
, 

### but they are both located on the property ofKennecott Utah Copper Corp. The general public does not have access to this area, and so these grid-cells do not represent ambient air. Results ofthe modeling analysis are presented below for each ofUtah'sthree PMIO 

### nonattainment areas. 

### Figure 

### IX.A.32. Highest Predicted 24-hr Concentration Salt Lake County

150



# - '"' 

# -5, 140 

# ..,.,..­ -24-hr Standard 

# { - 130

__ Peak Cell



# -­ .. -Ir- N. Salt Lake 

# - c: 120
___Hawthome c
___Cottonwood 0 0 110

___ Magna 0


## .... :& Q, 100


# -­ 

# ---­ -­ 90 2005 2008 2011 2014 2017 Projection Year



### Figure lX.A.32 above illustrates the trend ofpredicted concentrations at the monitoring stations and the highest modeled grid cells in the SaltLake County PM lO 

### nonattainment area and the entire domain. The peak cell is near the Cottonwood monitor. These data reflect the modeled PM lO 

### concentrations after application ofthe RRF. 

### .-.



# -.

Section IX.A.lO, page 25Adoptedby the Air Quality BoardJuly 6.2005 (-­ 

### Figure IX.A.33. 

### Highest Predicted 24-hr Concentration Utah County 

# t 155 150 145 ::l C 

### 140 0



# ....



# -------- /" 

# ...

..... 

# ---... /'



# -

2005 2008 

### 2011 2014 2017 Projection Vear 

### -24-hrStandard :=


# .. c 135 

### l!! -.-Undon 

## 8 130 -.-N. Pro\() 

### c 

# S 125 0 

# ... 120 ::E A. 

### 115 110

Figure IX.A.33 above illustrates the trend ofpredicted concentrations at the highest modeled grid-cells in the Utah County 

### PM IO nonattainment area. The highest 

### grid cell is located near the Lindon monitor. The data reflects the modeled 

### PM IO concentrations after application ofthe 

### RRF. The model predicts a significant margin of"safety" with respect to the health standard throughout the projection years.

Section IX.A.lO, page 26Adoptedby theAir Quality BoardJuly 

### 6. 2005



### Figure IX.A.34. Highest Predicted 24·hr Concentration Ogden City
155 ,-------------------., 150

# +-------------------+ E 145**+-------------------~** 

### "it! ::I. 140**+----------------~------__l** c 

### o 1-24-hr Standard 

## I 

# r:: +--------------------1 

## I Ogden
O o 

# .. I 

# - 125 

### +---------------------1 120 

### +-------------------,""'..,.'------! 

# .. --" 115

## -!-==:::~~=====~====::----_1 110 

## +----.....,.----..,....-----,r-------r----' 2005 2008 2011 2014 2017 Projection 

### Veer

Figure IX.A.34 above illustrates the trend ofpredicted concentrations at the highest modeled grid cells in the Ogden City PM IO nonattainment area. The monitoris located in this highest grid cell. The data reflects the modeled PMIO concentrations after application ofthe RRF. The model predicts a significant margin of"safety" with respect to the health standard throughout the projection years. (d) Annual Standard As presented above, the modeled demonstration ofmaintenance was designed to address the 24­ hour standard for PM 10 during the winter conditions that drive secondary aerosol formation. This scenario has historically led toelevated concentrations ofPM 10along the Wasatch Front. The attainment demonstrations in the 1991 PMIO SIP were also designed to address the 24-hour standard, based on EPA guidance which states that "The SIP related emission limits should 

### be based on the NAAQS (annual or 24-hour) which result in the most stringent control requirements" (see Subsection IX.A.9). As stated (by EPA or in that version ofthe SIP), it was assumed that "the application ofmany ofthe control strategies that are being implemented to reduce the 24-hour PM IO concentrations will also result in a reduction ofthe annual PM IO concentmtions even though they are designed toreduce wintertime 24-hr concentrations." Due to the disparity in concentrations observed during the remainder ofthe year, "the winter season is the period that has the greatest impact on the annual average (see TableIX.A.24), and controlling PMIO concentrations during the winter will have the greatest impact on the annual average." 

# -. As discussed in the section concerning improvements in air quality, the downward trend in the annual arithmetic mean concentrations is reflective ofthese control strategies, 

### many ofwhich Section IXA. 10, page 27Adopted by theAir Quality BoardJuly 

### 6. 2005

were directed at the wintertime 24-hourconcentrations. This corroborates the assumption made in the 1991 SIP. This maintenance plan will continue to rely upon that assumption. Since the control strategies required by the 1991 SIP were sufficient to achieve compliance with the 24-hour standard, the maintenance plan requires no new control strategies for continued compliance. Since the controls required by the 1991 SIPwere deemed sufficient to ensurecompliance withthe annual standard, no further controls will 

### be necessary to achieve continued compliance with that standard either. Thus, the modeled demonstration ofattainment for the 24-hour PMIO standard provides adequate assurance that the annual PMIO standard will be protected as well. (e) 

### Magna The violations ofthe PM

### 10 standard in Magna were caused primarily by the blowing oftailings from the Kennecott tailings pond undercertain meteorological conditions while the plant was shut down. While this scenario was never explicitly modeled in the 1991 SIP. it was addressed by requiring reasonably available control methods (RACM), which tookthe form of

### a comprehensive fugitive dust plan. The terms ofthis dust plan have been incorporated intothe SIP at Section 

### IX Part 

### H.
(2) 

### Attainment Inventory
1'­ The attainment inventory is discussed in EPA guidance (Calcagni) as anotherone ofthe core provisions that should 

### be considered by states for inclusion in a maintenance plan. According to Calcagni, the stated purpose ofthe attainment inventory is toestablish 

### the level of emissions during the time periods associated with monitoring data showing attainment. 

### In cases such as this, where a maintenance demonstration is founded on a modeling analysis, the attainment inventory is necessary to validate the model withrespect tothe ambient measurements that were made at the air monitoring locations during the commensurate period in time. Forthis analysis, base-year attainment inventories were compiled for 2001 and 2002. Continued attainment is then demonstrated by running an airquality model, which considers factors related to meteorology, topography. and certain stackcharacteristics as well as the emissions ofan air contaminant. After evaluating all ofthese factors. the model predicts concentrations ofthe air contaminant that are then compared tothe health standard. This implies that the analysis will require additional projection year inventories. Calcagni speaks to this as well, noting that the projection inventory should considerfuture growth. including population and industry. should 

### be consistent with the base-year attainment inventory. and should document data inputs and assumptions. Any assumptions concerning emission rates mustreflect permanent, enforceable measures. Utah has compiled both attainment and projection inventories for use in a quantitative modeling demonstration. Theemissions contained in the inventories include sources located within a regional area called a modeling domain. The modeling domain encompasses all three areas within the state that were designated as nonattainment areas for PM10: Salt Lake County, Utah County, and OgdenCity, as well as a bordering region see Figure IX.A.23.
Section IX.A.W. page 28AdoptedbytheAir Quality Board July 6, 2005


### There are three general categories ofsources included in these inventories: industrial point sources, smaller area sources, and mobile sources. For each ofthese source categories, the pollutants that were inventoried included: particulate matter with an aerodynamic diameter often microns or less (PM 10), 

### sulfur dioxide (502), 

### oxides ofnitrogen (NOx), carbon monoxide (CO), and volatile organic compounds (VOC). 

### S02 and NO

### x are specifically defined as PM 10 

### precursors, that is, compounds that, after being emitted to the atmosphere, undergo chemical orphysical change to become PMtO• 

### Any PM IO 

### that is created in this way is referred to as secondary aerosol. The UAM-AERO model also considers ammonia, CO and VOC to becontributing factors in the formation ofsecondary aerosol. The unit ofmeasure for point and area sources is the traditional tons per year, but the UAM· AERO model includes a pre-processorthat converts these emission rates to hourly increments throughout each day for each episode. Mobile source emissions are reported in terms oftons per day, and are also pre-processed by the model. The basis for the point source and area inventories, forboth the base-year attainment inventories as well as all future-year projection inventories, was 

### the 2001 inventory ofactual emissions that had already been compiledby theDivision ofAirQuality. Area sources, as well as the smallerpoint sources, were projected forward from 2001, using population and economic forecasts from the Governor's Office ofPlanning and Budget. The larger point sources - those whose emissions could exceed 100 tons peryear (tpy) ofPM 10, 

### 200 tpy NO

### x, or 250 tpy 

### S02

- were projected somewhat differently. These sources were evaluated at their maximum emissionrates, based on existing regulatory conditions ofoperation and construction. Furthermore,they wereevaluated 

### on their capability to emiton a short-term basis. As such, the projected emissions from these large sources reflect enforceable emission limits that are pertinent to the protection ofpublic health with respect to a 24-hour standard for PM 10. 

### Point source projections also include any current emission reduction credits (banked emissions). Mobile source emissions were calculated for each year using MOBILE6.1/6.2 in conjunction with the appropriate estimates for vehicle miles traveled (VMT). VMTestimates for the urban counties were based on a travel demand model that is only run periodically for specific projection years. VMT for intervening years were estimated by interpolation. Since this SIP subsection takes the form ofa maintenance plan, it must demonstrate that the area will continue to attain the PMJO 

### NAAQS throughout a period often years from the date ofEPA approval. It is also necessary to "spot check" this ten-year interval. Hence, projection inventories were prepared for the following years: 2005,2008,2011,2014, and 2017 (the ten-year mark from anticipated EPA approval). 2015 was also projected as p<;lssible planning year for the purpose of future transportation confonnity analyses. The following table is provided to sununarize these inventories. As described, they represent point, area, and mobile sources in the modeling domain. They include PMIO, 

### S02' NOx, 

### CO and VOC, and they span from the base-years (2001 and 2002) through the projection years of2005, 2008,2011,2014, and 2017. 

# -

Section IXAlO,

### page 29AdoptedbytheAir Quality BoardJuly 6, 2005


### ,­
Table IX.A.33 Emission Inventories for the

### Modeling Domain. Actual Emissions for 2001-2002; Emission Projections for 2005-2017
Input .cQ 2001 

## I 2002 

## I 2005 

## I 2008 

## I 2011 

## I 2014 

# I 2015 

## I 2017 

# I Point (TonslYear) • 30,850.43 25,237.47 63,184.04 64,254.04 65,401.66 66,512.50 66,882.78 67,590.87 Area (TonslYear) 184,125.74 186,748.59 195,132.88 203,263.30 211,525,98 219,584.84 222,202.47 227,463.10 On-Road (TonsJOay) •• 1,801.72 1,935.13 2,327.33 1,987.96 1,896.95 1,832.70 1,808.67 1,824.95

2001 

## I 2002 

## I 2005 

## I 2008 

## I 2011 

## I 2014 

## I 2015 

# I 2017 

## I Point (TonslYear) • 17,263.27 15.606.80 37,618.03 37,947.67 38,290.32 38,614.84 38,722.94 38,918.61 Area (TonSlYear) 31,822.89 31,665.83 31,555.39 31,043.87 30,622.93 30,660.63 30,756.97 31,044.91 On·Road (Tons/Day)" 160.57 161.19 181.55 145.70 117.38 90.91 84.96 82.75

2001 2002 2005 2008 2011 2014 2015 2017 fM1Jl 

## I I 

## I 

# I I I 

## I 

# I Point (TonsIYear) • 7,418.19 6,818.33 14,438.83 14,612.90 14,n9.78 14,938.94 14,991.99 15,077.57 Area (TonaIYear) 16,314.20 16,231.96 16,347.93 16,595.09 16,974.18 17.365.87 17,484.59 17,692.48 On-Road (Ton8lDay)·· 51.30 52.33 71.02 75.85 81.18 90.00 104.84 105.38 SQx 2001 

## I 2002 

## I 2005 

## I 2008 

## I 2011 

### 1 2014 

## I 2015 

## I 2017 

## I Point (TonaIYear) • 8,884.91 6,048.77 35,494.35 35,550.44 35,607.07 35,659.65 35,6n.17 35,703.41 Area (TonslYear) 2,134.56 2,149.09 2,219.34 2,294.93 2,370.11 2,441.92 2,465.20 2,510.63 On·Road (TonslOay)

.. 5.32 5.46 7.29 7.43 8.04 8.63 8.83 8.83

2001 

## I 2002 

## I 2005 

## I 2008 

## I 2011 

## I 2014 2015 

## I 2017 

## I 

# I Point (TonslYear) • 5,309.57 5,183.67 8,034.87 8,206.38 8,379.58 8,545.44 8,600.73 8,696.39 Area (TonsIYear) 150,738.67 150,585.37 151,664.80 153,339.12 156.232.05 159,330.42 160,290.66 162,032.65 On-Road (TonslDay) •• 89.16 89.44 88.80 71.74 60.37 51.39 49.96 49.n
• Point source totals for 2001 & 2002 include slight variations between specific episode days. The numbers reported In this table reflect the highest number for each pollutant. Banked emissions are Included In all projection year inventories (2005 forward)

. •• On-Road sourcetotals for every year include slight variations between specific episode days. The numbers reported in this table reflect the episode day on which the NOx and the PM10 were the highest.



### More detail concerning any element ofthe inventory can be 

### found at the appropriate section of the Technical Support Document (TSD). More detail about the general construction ofthe inventory may be 

### found in the Inventory Preparation Plan at Section 1.a ofthe TSD. Discussion concerning any adjustments that were made tothe inventoried emissions prior to use in the UAMAERO model may be found in the modeling section ofthe TSD.

. 

### (3) Emissions Limitations As discussed above, there was a distinction made in the modeling ofprojected emissions for the point source category. The larger sources within the modeling domain were modeled at their maximum allowable emissions. as determined on a 24-hour basis. A subset ofthese "large" sources was subsequently identified for the purpose ofestablishing emission limitations as part ofthe Utah SIP. This subset includes any large source located within any ofthe three current nonattainment areas for PM1o: 

### Salt Lake County, Utah County, or Ogden Section IXA.lD, page 30Adopted bytheAir Quality Board July6. 2005 

### City. A source was also included in the subset ifit was currently regulated for PMIQ under section IX, Part H ofthe Utah SIP. There were several sources in Davis County that were close enough to the border so as tohave originally been included in the original 

### PMIO 

### SIP. As discussed before, the emission limits for these sources had already been reflected in the projected emissions inventories used in the modeling analysis. Many ofthese limits appear in State issued Approval Orders orTitle 

### V Operating Permits. Such regulatory documents typically include many emission limits and operating restrictions. Only those limits that are truly significant from an airshed management perspective have been incorporated specifically into the SIP. Theselimits are incorporated in the Utah SIP at Section 

### IX. Part 

### H (formerly Sections 1 and 2 of Appendix A to Section 

### IX, Part A), and as such remain federally enforceable. Theseconditions demonstrate maintenance through 2017 see subsections IX.A.lO.c.( 1) and (2). 

### (4) Emission Reduction Credits Existing EmissionReduction Credits on file with the Utah Division ofAirQuality were included in the modeled demonstration ofmaintenance outlined 

### in SubsectionIX.A.IO.c( 1). Concerning the subsequent banking ofany emission reduction credits for PMIQ, orprecursors thereto, the emission levels contained 

### in the modeled demonstration ofmaintenance outlined in Subsection IX.A.lO.c(l). or incorporated into the Utah SIP at Section IX, Part H (formerly Appendix A to Section IX, Part A,) should serve toestablish a baseline for theemission rates relied upon by this maintenance plan. Theseemission reduction credits, whether pre-existing or established subsequent to the approval ofthis SIPrevision. are alJowed to the extent that they are established by actual, verifiable. and enforceable reductions in emissions. 

### (5) Additional Controlsfor FutureYears Since the emission limitations discussed in subsection IX.A.1O.c.(3) remain federally enforceable and, as demonstrated in IX.A.lO.c(I) 

### above, are sufficient toensure continued attainment ofthe PM 10

### NAAQS, there is no need to require any additional control measures to maintain the PM IO 

### NAAQS. 

### (6) Mobile Source Budgetfor Purposes ofConformity The transportation conformity provisions ofsection l76(c)(Z)(A) ofthe Clean Air Act (CAA) require regional transportation plans and programs to show that"

...emissions expected from implementation ofplans and programs are consistent with estimates ofemissions from motor vehicles and necessary emissions reductions contained in the applicable implementation plan

... " EPA's transportation confonnity regulation (40 CFR 93.118, last amended at 69 FR40072, July 1,2004) 

### also requires that motor vehicle emission budgets must be established for the last year of the maintenance plan, and may be established for any years deemed appropriate. Ifthe maintenance plan does not establish motor vehicle emissions budgets for any years other than the last year ofthe maintenance plan, the conformity regulation requires that a "demonstration of 

# - consistency with the motor vehicle emissions budgets must be accompanied by a qualitative finding that there are not factors which would cause orcontribute lO 

### a new violation orexacerbate an existing violation in the years before the last year ofthe maintenance plan." The normal Section IX.A.IO, 

### page 31Adopted by theAir Quality Board July 6, 2005

{,­ interagency consultation process required by the regulation shall determine what must be considered in orderto make such a finding. Road dust projections were estimated using the EPA PART5 particulate emissions model. However, prior to applying these emission estimates in an attainment demonstration using the UAM-AERO model, the road dust inventory was discounted by 75% as part ofthe attainment modeling method to more accurately reflect the conventional understanding ofthe relationship of modeled road dustemissions and actual fugitive dust measurements recorded by the State air quality monitoring network. The mobile source budgets set forth in this Plan for direct PMIO (including road dust) are based on the unmodified estimates from the PART5 model, and as such, no discount adjustments should 

### be applied as part ofthe regional emissions analysis for future conformity determinations. For transportation plan analysis years afterthe last year ofthe maintenance plan (in this case 2017), 

### aconformity detennination must show that emissions 

### are less than or equal to the maintenanceplan's motor vehicle emissions budget(s) for the last year ofthe implementation plan. Mobile sources 

### are not significant contributors ofS02' This SIPdoes not establish a motor vehicleemissions budgetfor 

### S02' 

### (a) SaltLakeCouotyMobile Source PM10 

### Emissions Budgets In this maintenanceplan, the State is establishing transportation confonnity motorvehicle emission budgets (MVEB)for 2015 and 2017. 

### (i) Direct PM10 

### Emissions Budget As presented in the Technical Support Document (SMOKEFormats for Urban Counties), estimated on-road mobile source emissions for SaltLake County, in 2015 and 2017, ofdirect sources ofPM IO (road dust, brake wear, tire wear, and exhaust particles) were 48.86 tons per winter weekday. The maintenance demonstration in Subsection IX.A.lO.c.(I)estimates a maximumPM IO concentration of 147.7 uglm3 in 2017 within the Salt Lake County portion ofthe modeling domain. This value is 2.3 ug/m3 below the NAAQS of 150 uglm3• EPA's confonnity regulation (40 CPR 93.124) also allows the implementation plan toquantify explicitly the amount by which motor vehicle emissions could be higher while still demonstrating compliance with the maintenance requirement. The implementationplancan then allocate some or all ofthis additional "safety margin" to the emissions budgets for transportation confonnity purposes. 

### In this case, the safety margin equates to 2.3 ug/m3

. Using the same emission projections for point and area and non-road mobile sources. the UAMAERO model was re-run using 52.00tons ofPMlO per winter weekday for mobile sources (and 35.00 tons/winter weekday ofNO

### x). Therevised maintenance demonstration for 2015 and 2017 still shows maintenance ofthe PMIO standard. It estimates a maximumPM IO concentration of 148.5 ug/m3 in 2017 within the Salt Lake County portion ofthe modeling domain. This value is 1.5 ug/m3 below the NAAQ Standard of 150ug/m3• This maintenance plan allocates 0.8 ug/m3 of the safety margin to the transportation MVEB. and thereby sets the direct PM 10 MVEB for 2015 and 2017 at 52.00 tons/winter weekday. In terms ofemissions, the safety margin can be described as follows: Using 52.00 tons per day of PM\o and 35.00 tons per day ofNO

### x when modeling mobile source emissions in 2015 and 2017, Section IX.A.!O. page 32Adoptedby theAir Quality BoardJuly 6. 2005
the highest predicted concentration ofPM 1o was 

### 148.5lLglcubic meter within the Salt Lake County portion ofthe modeling domain. This shows that the safety margin is at least 3.14 tons perday ofPM,o (52.00 tons perday minus 48.86tons perday) and 0.04tons per day ofNOx (35.00 tons per day minus 34.96 tons perday). This maintenance plan allocates a portion ofthe safety margin to the mobile sourcebudgets. Mobile sources are not significant contributors ofdirect 

### S04 exhaustparticulates. This SIP does notestablish a separate

### MVEB for 

### S04' (ii) 

### NOx

### EmissionsBudget NOxemissions indirectly contribute to PMIO concentrations through secondary chemical reactions and for this reason are sometimes referred to as indirect or secondary PMIO• As presented in theTSD (SMOKEFonnats for Urban Counties), estimated on-road mobile source NOx emissions 

### in 2015 and 2017 were 34.96 tons per winter weekday. The maintenance demonstration in Subsection IX.A.lO.c(l} estimates a maximumPMIO concentration of 147.7 uglm3in2017 within the SaltLake Countyportion ofthe modeling domain. This value is 2.3 uglm3 below

### the NAAQS of 150 uglm3. EPA's conformity regulation (40

### CPR 93.124) also allowsthe implementation plan toquantify explicitly the amount by which motor vehicle emissions couldbe higherwhile still demonstrating compliance with 

### the maintenancerequirement. The implementation plan can then allocate some or all ofthis additional "safety margin" to

### the emissionsbUd§ets for transportation conformity purposes. Inthis case, the safety margin equates to2.3 uglm

. 

# - Using the same emission projections for point and area and non-road mobile sources, the UAM­ AERO model was re-run using 35.00 tons ofNOxper winter weekday for mobile sources (and 52.00 tons/winter weekday of

### PMJO). Therevised maintenance demonstration for 2015 and 2017 still shows maintenance ofthe PM10 standard. It estimates a maximumPMIO concentration of 148.5 uglm3in 2017 within the Salt Lake County portion ofthe modeling domain. This value is 1.5 uglm3 below the NAAQS of 150 uglm3• This maintenance plan allocates 0.8 uglm3 ofthe safety margin to the transportation 

### MVEB, and thereby sets the NO

### x

### MVEB for 2015 and 2017 at 35.00 tons/winter weekday. 

### In terms ofemissions. the safety margin can be described as follows: Using 52.00 tons perday of PM 10 and 35.00 tons perday ofNO

### x when modeling mobile source emissions in 2015 and 2017, the highest predicted concentration ofPM10 was 148.5 JLglcubic meter within the Salt Lake County portion ofthe modeling domain. This shows that the safety margin is at least 3.14 tons per day ofPM IO (52.00 tons per day minus 48.86 tons perday) and 0.04 tons perday ofNOx (35.00 tons perday minus 34.96 tons perday). 

### This maintenance plan allocates a portion of

### the safety margin to the mobile source budgets. 

### (b) Net ElTed to MaintenanceDemonstration Using the procedure described above. some ofthe safety margin indicated earlierin Subsection IX.A.IO.c(6) has been allocated to the mobile vehicle emissions budgets. The results ofthis modification are presented below. 

# -

Section IX.A.IO, page 33Adoptedby the Air Quality BoardJuly 6, 2005

(i) Inventory: The emissions inventory was adjusted by adding the following sums tothe onroad mobile source emissions totals for the entire modeling domain: in 2015: 4.04 ton/day PMIO and 0.19 ton/day NOx in 2017: 5.41 ton/day PMIO and 2.49 ton/day NO

### x (ii) Modeling: The effect on the modeling results throughout the domain is sununarized in the following table (which shows predicted concentrations in ug/m3). It demonstrates that with the allocation ofthe safety margin, the NAAQS is still maintainedthrough 2017 in all areas.


### Table IX.A.34 Modeling ofAttainment, 2005

- 2017, 

### IncludingthePortionofthe Safety 

### MarginAllocated to

### MotorVehicles

2001 BaseYear 

### E Isode 2005 2008 

### 2011 2014 2015 Cottonwood 

### 91.45 89.13 88.57 89.92 93.40 Hawthome 

### 124.17 121.71 119.76 120.84 125.60 

# 0·­ Magna 

### 81.33 80.32 

### 80.11 80.52 N. Salt Lake 

### 144.05 143.07 142.96 144.37 Ogden 

### 113.19 113.04 113.75 116.62

### 121.75~f'l"ii.a11 133.2<1iiWl Lindon 

### 78.82 81.00 82.97 84.79 90.16

## 90.3~**91.9~ 92.1~**  N. Provo 

### 62.04 62.22 63.50 65.11 69.68 69.8 71.4 71.6 Plus safety Marain 

### 80.44 81.91 147**.27t;'~1:-~'···**



### 2002 Base Vear Episode 

### 2005 2008 

### 2011 2014 2015 2017 Cottonwood 

### 132.83 125.45 121.54 121.08 124.04**125.2~** Hawthorne 

### 136.60 127.78 122.80 122.03 125.35 126.61 Magna 

### 93.92 94.03 95.34 96.73 96.00 98.47 N. Salt Lake 

### 148.77 139.92 134.87 133.19 136.01 137.27 Peak Cell (nearCottonwood) 

### 149.97 140.36 134.92 133.85 137.43 138.75 2015 2017 125.3e 126.56 126.13 127.98

96.60 99.07 137.41 138.66 139.0B 

### 140.39 Ogden 

### 117.70 116.09 116.02 117.59 121.20 122.121

### 126.6~ 127.511 Lindon 

### 131.09 126.27 124.12 123.87 127.71·· N. Provo 

### 122.46 118.22 116.74 117.34 121.60
(7) 

### NonattainmentRequirements ApplicablePendingPlan Approval CAA 175A(c)

- Until suchplan revision is approvedandan area is redesignatedasattainment. the requirements of

## eM Part D, Plan Requirements/orNonattainmentAreas, shall remain in force andeffect. The Clean AirAct requires the continued implementation ofthe nonattainment Section lX.A.lO, page 34Adoptedby theAirQuality BoardJuly 6,2005



### area control strategy unless such measures are shown to 

### be unnecessary for maintenance orare replaced with measures that achieve equivalent reductions. Utah will continue to implement the emissions limitations and measures from the PMJO SIP. 

### (8) Revise in Eight Years CAA 

### 175A(b) • Eight years after redesignation. the State mustsubmitan additionalplan revision which shows maintenanceof the applicable NMQS for an additional 10years. 

### Utah agrees to fulfill this obligation at the appropriate point in time. 

### (9) Verification ofContinued Maintenance Implicit in the requirements outlined above is the need for the State to determine whether the area is in fact maintaining the standard it has achieved. There are two complementary ways to measure this: 1) by monitoring the ambient air for PMJ(lt and 2)by inventorying emissions of PM10 and its precursors from various sources. The State will continue to maintain an ambient monitoring network for PMlO 

### in accordance with 

### 40 CFRPart 58 and the Utah SIP. The State anticipates that the EPA will continue toreview the ambient monitoring network for PMJO each year, and any necessary modifications to the network wiJI 

### be implemented. The State 

### will also continueto collect actual emissions inventory data from all sources ofPMIO, 

### S02' and NOxin excess of

### 25 tons (in aggregate) peryear, as required by

### R307-150. 

### (10) ContingencyMeasures eM 175A(d)

- Each maintenanceplan shall contain contingency measures to assure that the State willpromptly correctany violation of the standardwhich occurs afterthe redesignation of the area to attainment. Suchprovisions shall include a requirement that the State will implement all control measures which were contained in the SIPpriorto redesignation. 

### Utah has· implemented all measures contained in the plan, and will continue to do soeven after redesignation. This revision need only address such contingency measures as may be 

### necessary to mitigate any future violation ofthe standard. This Contingency Plan for Salt Lake County supercedes Subsection IX.A.8, Contingency Measures, which is part ofthe original PM IO 

### SIP. The State will rely upon ambient PM IO 

### monitoring to determine whether a violation has occurred. Upon monitoring a violation ofthe PM 10 

### NAAQS, the State will take the following actions.

• The State will identify the source(s) ofPM1o causing the violation, and report the situation to EPA Region VIII within four months.

• The State will identify a means ofcorrective action within six months. The maintenance plan contingency measures to be 

### considered and selected will be chosen from the following list or any other emission control measures deemed appropriate based on a

Section IX.A.lO, page 35Adoptedby the Air Quality BoardJuLy 6, 2005
consideration ofcost-effectiveness, emission reduction potential, economic and social considerations, or other factors that the State deems appropriate: Re-evaluate the thresholds at which a red oryellow burn day is triggered, as established in R307-302; Furthercontrols on stationary sources; The State will require implementation ofsuch corrective action no later than one year after the violation was confmned.

Section IX.A.lO, page 36