International Corporation 

### Air Sciences

Technical Support Document

CARBON MONOXIDE MODELING

FOR THE CLARK COUNTY MAINTENANCE PLAN

Prepared for

Clark County Department of Air Quality and Environmental Management 500 S. Grand Central Parkway

PO Box 551776 Las Vegas, NV 89155-1776

Prepared by

Chris Emery Gary Wilson Stella Shepard

John Grant

ENVIRON International Corporation

773 San Marin Drive, Suite 2115
Novato, CA 94998

May 19, 2008

773 San Marin Drive, Suite 2115, Novato, CA 94998 415.899.0700May 2008

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### i TABLE OF CONTENTS

Page

1. INTRODUCTION............................................................................................................... .. 1-1

1.1 Background................................................................................................................ 1-1 1.2 Modeling for the Maintenance Plan........................................................................... 1-3

2. EMISSION PROCESSING................................................................................................. 2-1

2.1 Overview of Approach............................................................................................... 2-1

2.2 On-Road Mobile Sources........................................................................................... 2-1 2.3 Non-Road Emission Categories............................................................................... 2-18

2.4 Area Sources ............................................................................................................ 2-20

2.5 Point Sources ........................................................................................................... 2-20 2.6 Summary of Total Emissions................................................................................... 2-21

3. MODELING RESULTS...................................................................................................... 3-1

3.1 Overview of Approach............................................................................................... 3-1

3.2 UAM Simulations ...................................................................................................... 3-2 3.3 Microscale Modeling ................................................................................................. 3-9 3.4 Estimating On-Road Emission Budgets................................................................... 3-11

4. SECTION 110(l) REQUIREMENTS.................................................................................. 4-1

4.1 Ozone ..................................................................................................................... .... 4-1

4.2 Particulate Matter....................................................................................................... 4 -2

REFERENCES.......................................................................................................................... R-1

TABLES

Table 2-1 MOBILE6.2 input para meters for Las Vegas runs .............................................. 2-3 Table 2-2 Adjustment factor to scale link-level emissions to account for mass

transit and traffic control measures...................................................................... 2-6 Table 2-3 2008 VMT by facility type . Totals are shown as output by TransCAD, and after seasonal, day-of-week, and public transit adjustments .......................................................................................................... 2-8 Table 2-4 2010 VMT by facility type . Totals are shown as output by TransCAD, and after seasonal, day-of-week, and public transit adjustments .......................................................................................................... 2-9 Table 2-5 2020 VMT by facility type . Totals are shown as output by TransCAD, and after seasonal, day-of-week, and public transit adjustments ........................................................................................................ 2-10May 2008

G:\Las Vegas CO MP\TSD\TOC.doc 

### ii Table 2-6 Component and total on-road mobile source CO emissions (TPD) for all future years from the AIR version of MOBILE6.................................... 2-12 Table 2-7 Component and total on-road mobile source CO emissions (TPD) for all future years from the Sierra-modified version of MOBILE6 ................. 2-12

Table 2-8 Annual CO emissions re ported for Nellis AFB (TPY)...................................... 2-18 Table 2-9 Summary of inputs used for NONROAD modeling future years...................... 2-19 Table 2-10 Modeling CO point source emission estimates (TPD) ...................................... 2-21 Table 2-11 Summary of total daily CO emissions (TPD) in the UAM CO

Maintenance Plan. On-road mobile emissions are taken from the

AIR version of MOBILE6 ................................................................................. 2-21 Table 3-1 Domain-peak 8-hour CO ( ppm) from each UAM simulation ............................. 3-2 Table 3-2 Peak 8-hour average CO c oncentrations (ppm) predicted by UAM, CAL3QHC, and UAM+CAL3QHC for each future year and for

each of the Five Points intersections . Note that peaks reported for

each of the models and their comb ined effect occur over different 8-hour periods .................................................................................................... 3-10 Table 3-3 Peak total UAM + EDMS 8-hour CO concentrations (ppm) at all three airports and for all future years evaluated. Values shown for McCarran airport occur at the peak publicly accessible receptor...................... 3-10

Table 3-4 Grid definition of th e central urban sub-domain................................................ 3-11 Table 3-5 Weekday domain-wide on-road emission increase, net on-road

emission increase that includes an additional 60% increase outside the central urban sub-domain, re sulting UAM predicted peak CO, and resulting total and sub- domain on-road emission budgets (December 9) for each future year..................................................................... 3-12 Table 3-6 Peak 8-hour average CO c oncentrations (ppm) predicted by UAM, CAL3QHC, and UAM+CAL3QHC for each future year, and for

each of the Five Points intersec tions. UAM and CAL3QHC results

are taken from the on-road sensitiv ity scaling tests. Note that peaks reported for each of the m odels and their combined effect occur over different 8-hour periods ................................................................... 3-12 Table 3-7 Peak total UAM + EDMS 8-hour CO concentrations (ppm) at all three airports and for all future years evaluated. Values shown for McCarran airport occur at the peak publicly accessible receptor.

UAM results are taken from the on-ro ad sensitivity scaling tests ..................... 3-13

Table 4-1 Total PM10 Mobile Source Emissions for 2006.................................................. 4-2

Table 4-2 2006 24-Hour Controlled PM10 Emissions......................................................... 4-3

FIGURES

Figure 2-1 Hourly weekend and wee kday start distributions (fraction) provided by Clark County, used to temporally allocate emissions

derived from TransCAD. ..................................................................................... 2-4 Figure 2-2 Fraction of original weekda y start distribution (from Figure 2-1)

and start distributions in all future years for the Las Vegas

Boulevard area calculated from the TransCAD origin trips by TAZ (from the 2005 CO SIP Revision)........................................................................ 2-5May 2008

G:\Las Vegas CO MP\TSD\TOC.doc 

### iii Figure 2-3 Hourly start emission fact ors from the MOBILE6 runs: “Sun EF” is the Sunday profile used for a ll start emissions; “Mon EF” is the Monday profile used for start emi ssions outside of the LVB area; and “LVB Mon EF” is the Monday pr ofile used for start emissions

within the LVB area............................................................................................. 2-5 Figure 2-4 Weekday and Sunday hourly VMT distribution.................................................. 2-7 Figure 2-5 Spatial distribution of tota l on-road mobile source CO emissions on December 9 for the 2008 future year (u sing AIR version of MOBILE6) ......... 2-13 Figure 2-6 Spatial distribution of tota l on-road mobile source CO emissions on December 9 for the 2010 future year (u sing AIR version of MOBILE6) ......... 2-14 Figure 2-7 Spatial distribution of tota l on-road mobile source CO emissions on December 9 for the 2020 future year (u sing AIR version of MOBILE6) ......... 2-15 Figure 2-8 Spatial distribution of tota l on-road mobile source CO emissions on December 9 for the 2020 future year (taken from the 2005 CO SIP Revision)............................................................................................................ 2-16 Figure 2-9 Difference in total on-road mobile source CO emissions on December 9 for the 2020 future year. The field shown in Figure 2-8 is subtracted from the field shown in Figure 2-7 .................................................................... 2-17 Figure 2-10 Hourly activity pr ofile used to temporally allocate non-road emissions ........... 2-20 Figure 2-11 Spatial distribution of total surface gridded CO emissions on December 9 for the 2008 future year (using AIR version of MOBILE6).............................. 2-22 Figure 2-12 Spatial distribution of total surface gridded CO emissions on December 9 for the 2010 future year (using AIR version of MOBILE6).............................. 2-23 Figure 2-13 Spatial distribution of total surface gridded CO emissions on December 9 for the 2020 future year (using AIR version of MOBILE6).............................. 2-24 Figure 3-1 Spatial distribution of UAM predicted 8-hour maximum CO concentrations (ppm) for the December 8-9, 1996 episode using emission forecasts for 2008 (AIR version of MOBILE6) ................................... 3-3 Figure 3-2 Spatial distribution of UAM predicted 8-hour maximum CO concentrations (ppm) for the December 8-9, 1996 episode using emission forecasts for 2010 (AIR version of MOBILE6) ................................... 3-4 Figure 3-3 Spatial distribution of UAM predicted 8-hour maximum CO concentrations (ppm) for the December 8-9, 1996 episode using emission forecasts for 2020 (AIR version of MOBILE6) ................................... 3-5 Figure 3-4 Spatial distribution of UAM predicted 8-hour maximum CO concentrations (ppm) for the December 8-9, 1996 episode using emission forecasts for 2008 (Sierra-modified version of MOBILE6)........................................................................................................... 3-6 Figure 3-5 Spatial distribution of UAM predicted 8-hour maximum CO concentrations (ppm) for the December 8-9, 1996 episode using emission forecasts for 2010 (Sierra-modified version of MOBILE6)........................................................................................................... 3-7 Figure 3-6 Spatial distribution of UAM predicted 8-hour maximum CO concentrations (ppm) for the December 8-9, 1996 episode using emission forecasts for 2020 (Sierra-modified version of MOBILE6)........................................................................................................... 3-8 Figure 3-7 Location of the central urban sub-domain used in the UAM sensitivity tests (heavy red line)......................................................................... 3-11May 2008

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### iv Figure 3-8 Spatial distribution of UAM predicted 8-hour maximum CO concentrations (ppm) for the December 8-9, 1996 episode using

emission forecasts for 2008 with increased on-road mobile source emissions to reach peak CO just under 9.0 ppm (AIR version of MOBILE6)......................................................................................................... 3-14 Figure 3-9 Spatial distribution of UAM predicted 8-hour maximum CO concentrations (ppm) for the December 8-9, 1996 episode using

emission forecasts for 2010 with increased on-road mobile source emissions to reach peak CO just under 9.0 ppm (AIR version of MOBILE6)......................................................................................................... 3-15 Figure 3-10 Spatial distribution of UAM predicted 8-hour maximum CO concentrations (ppm) for the December 8-9, 1996 episode using

emission forecasts for 2020 with increased on-road mobile source emissions to reach peak CO just under 9.0 ppm (AIR version of MOBILE6)......................................................................................................... 3-16May 2008

G:\Las Vegas CO MP\TSD\Sec_1_Intro.doc 

### 1-1 1. INTRODUCTION

1.1 BACKGROUND

The Las Vegas Valley is a large desert basi n at about 2000 feet el evation, surrounded by mountain ranges up to 11,900 feet, making it quite su sceptible to air pollu tion problems. This area includes the City of Las Vegas, the City of North Las Vegas, and the City of Henderson. The remainder constitutes unincorporated areas of Clark County. Clark County has been the fastest growing area of the United States over the past 50 years, with a current population of nearly 2,000,000 (UNLV, 2008). During the winter months, cold air masses stagnate over the region, and nightly temperature in versions trap pollutants within the valley. The overnight buildup of pollutants has historically caused viol ations of the national carbon monoxide standard in a limited area surrounding the East Charleston (now Sunrise Acres) monitoring station. This monitoring site in the vicinity of converging major transporta tion corridors named the “Five Points,” where three state highways intersect. Additionally, the site is located within a local depression where air pollution often collects.

The 1990 Clean Air Act Amendments (CAAA) esta blished two National Ambient Air Quality Standards (NAAQS) for carbon monoxide (CO). The first sets a maximum allowable concentration of 35 parts per million (ppm) av eraged over 1 hour, and the second sets a maximum concentration of 9 ppm 1 

### averaged over 8 hours. Areas th at exceed one or both of the

ambient standards more than two times in a tw o-year period are in vi olation and are thus

classified as non-attainment areas for carbon monoxide.

Although the Las Vegas Valley has never exceeded the 1 hour CO NAAQS, it has previously

exceeded the 8 hour standard at least once per year on a winter seasonal basis. The last

exceedance of the 8-hour standard occurred in 1998 in the Five Points area and measured 10.3 ppm. There have been no CO exceedances since 1998. This downtrend is the direct result of the implementation of local CO control measures and the tighter federal motor vehicle emission

standards.

1.1.1 CO Regulatory History

The number and severity of hist orical 8-hour CO violations ca used the U.S. Environmental Protection Agency (EPA) to automatically desi gnate the Valley as a “moderate” nonattainment area upon enactment of the 1990 CAAA on Novemb er 15, 1990. Moderate nonattainment areas were required to implement emission control meas ures as “expeditiously as practicable” in order to attain the CO NAAQS by D ecember 31, 1995. Clark County implemented the set of controls required by the Clean Air Act for CO nonattainme nt areas, and made great strides towards attaining the 8-hour standard. However, due to phenomenal growth within the Las Vegas Valley, it fell short of meeting the NAAQS by the a pplicable attainment date. EPA then granted Clark County a one year extension to demonstr ate compliance with the NAAQS. Still, the Las Vegas Valley was not successful in ac hieving compliance by December 31, 1996.

1 Note that when rounding is taken into account, the CO co ncentration required to exceed the 8-hour standard is 9.5

ppm.May 2008

G:\Las Vegas CO MP\TSD\Sec_1_Intro.doc 

### 1-2 According to CAAA requirements, the EPA recl assified the Las Vegas Valley as a “serious”

nonattainment area for carbon monoxide on October 2, 1997. A deadline of May 1999 (18 months from the notice publication date) was set for submission of a State Implementation Plan (SIP) that demonstrated attainment by December 31, 2000. The resulting 2000 CO State Implementation Plan (SIP) for Clark County c ontained local measures for attaining the standards, including wintertime gasoline specif ications. In June 2005 the EPA found that the valley had attained the standards by the applicable attainment date.

Later, Clark County submitted a 2005 CO SIP Re vision, which included revised and improved methodologies for estimating on-road mobile s ource emissions (the chief component of CO emissions in the valley), and extended future year estimates of CO concentrations out to 2030 to

demonstrate maintenance of the standards and to establish conform ity emission budgets for multiple future years. No changes in actual c ontrol regulations were incorporated into the 2005

CO SIP Revision.

1.1.2 Previous CO Modeling

Between 1996-2000, the Clark County Department of Comprehensive Planning developed computer models for valley-wide carbon monoxide to provide technical support for the control measures being evaluated for the 2000 CO SIP. This modeling was developed and conducted according to CAAA requirements and followed EPA modeling guidance specific to 8-hour CO SIP demonstrations. Modeling was conducted for three historical CO episodes in 1995-96 using a combination of numerical models, each focusing upon a specific scale and issue. The Urban Airshed Model (UAM) was used to simulate epis odic urban-scale CO patterns on a grid with 1- km spacing over the entire de veloped portion of the Las Vegas Valley; the CAL3QHC

intersection model was used to simulate mi cro-scale CO patterns at the “Five Points” intersections; and the EDMS air port model was used to simulate fine-scale emissions and CO concentration patterns at the three civil airpor ts in the area, including McCarran International Airport, North Las Vegas, and Henderson.

At the time, CO emissions from on-road mobile sources (by far the larg est contributor to the overall emission inventory for Las Vegas) we re estimated using a combination of EPA’s MOBILE5b emission factor model, the Direct Trav el Impact Model (DTIM), and vehicle volume information provided by the Regional Transpor tation Commission (RTC ) via their TRANPLAN transportation demand model (TDM). Ultimately the 2000 CO SIP was based on modeling results for the single best performing episode ofthe three: the night of December 8-9 (SundayMonday), 1996.

In 2005, the Clark County Department of Air Qu ality and Environmental Management updated their UAM CO modeling and conformity analysis using the latest tools, data resources, and methodologies available to estimate CO emissi ons. From the revised modeling results, Clark County submitted the 2005 CO SIP Revision. Continuing with the use of the previous UAM/CAL3QHC/EDMS modeling datasets deve loped for the December 8-9, 1996 episode, specific updates to the emission inventories were made, includ ing modifications to on-road mobile, non-road mobile, civil airports, railroad s and point sources. Ne w spatial distributions were developed for area sources from updated land use projections. The future years modeled in this update included: 2006, 2010, 2015, 2020, and 2030.May 2008

G:\Las Vegas CO MP\TSD\Sec_1_Intro.doc 

### 1-3 The greatest effort in the 2005 CO modeling update focused on the on-road mobile source inventory estimates. MOBILE5b was replaced by the latest version of the model,

MOBILE6.2.03. The TRANPLAN TDM link-level traffic volumes were replaced with improved and broader datasets generated usi ng the GIS-based TransCAD TDM. DTIM was replaced by two new programs, one to process th e link-based emissions and another to process

start and intra-zonal emissions based on traffi c analysis zones (TAZ). Additionally, NEVESbased non-road emission estimates were repl aced with EPA’s NONROAD2004 model, run with Clark County input data and act ivity profiles. Railroad esti mates were improved based on a study conducted by Mactec (2003). Finally, improvements were incorporated for the CO

emission inventories from the thr ee civil airports. Th e latest version of EDMS was used, which introduced the AERMOD dispersion model and included emission factor inputs from

MOBILE6.2.

1.2 MODELING FOR THE MAINTENANCE PLAN

Clark County is in the process of requesting a reclassification of its CO designation from nonattainment to attainment by EPA. As part of this re-designati on request, the EPA has expressed a desire for the DAQEM to perform new modeling calculations using current population variables

in the most recent TransCAD TDM for the Las Vegas Valley in its CO Maintenance Plan.

The modeling conducted in support of the CO Maintenance Plan followed the procedures developed for the 2005 CO SIP Revision. Howe ver, updated TransCAD TDM output was used, in parallel to the recent ozone SI P modeling, in addition to new wi ntertime fuel specifications. In addition, emissions from Nellis Air Force Base were updated according to the latest information from DAQEM. The following fu ture years were simulated: 2008, 2010, and 2020. Note that the original 2006 futu re year modeled in the 2005 CO SIP Revision was replaced with the 2008 future year in this work.

The revised CO UAM modeling used RTC TransCAD runs that they performed in 2006 to

define on-road mobile source ac tivity and distributions , in a manner consistent with the ozone SIP modeling. Start and running ex haust emissions were calculated and distributed in time and space in the same manner as performed for the CO SIP revision with modifications as necessary

to accommodate the different TAZ definitions in the updated TransCAD model. Although the current I/M program was maintained in all future years, a new fuel was specified for all years comprising a 13.5 RVP with the cu rrent 3.5% oxygenate, with no fu rther fuel controls (no CBG, no TCM adjustments, and no alternative fuel programs for government fleets). EPA's MOBILE6.2 (Air Improvement Reso urce’s version, which allows more detail in the database output to support the processing for this particular approach) was run for all years. Additionally,

Sierra Research's modified version of MOBI LE6.2, which improves the estimate of RVP effects on later model vehicles (Sierra Re search, 2003), was used for all thr ee future years to develop an

alternative set of on-road m obile emissions. The NONROAD2005 model was used to calculate non-road emissions for the new gasoline specifications in all years; this model is also consistent

with the version used in the ozone SIP.

Given that the original 2006 future year in th e 2005 CO SIP Revision wa s replaced with the 2008 future year in this work, stationary CO em issions needed to be generated for 2008. Area emissions were interpolated from the existing 2006 and 2010 inventories and allocated in space using 2006 spatial surrogates. Civil airport and ra ilroad emissions were similarly interpolated.May 2008

G:\Las Vegas CO MP\TSD\Sec_1_Intro.doc 

### 1-4 Since point source emissions are held constant for all years, they were used for 2008 without

modification.

UAM was run for the 2008, 2010, and 2020 future years using the revised emission inventories. Following the methodology used in the 2005 CO SI P Revision, UAM was run in two ways: one

in which all emissions were included in the m odel, and another in which emissions from the three civil airports were removed to mini mize double-counting of airport impacts when UAM

results are combined with EDMS results. Note th at EDMS was not re-run in this project; EDMS

model results from the 2005 SIP Revision were used without modification for 2010 and 2020. It is also important to note that traffic volumes on the major roadways within the McCarran airport property are included in both EDMS and TransCAD. As a result, the EDMS+UAM CO

concentration results for McCarra n reflect a double-counting of por tions of the on-road mobile source emissions on that property, and so the CO concentrations reported for McCarran are conservative (i.e., high) estimates. EDMS recepto r concentrations for 2008 were interpolated from 2006 and 2010. CAL3QHC was re-run in th is project for the three “Five Points” intersections for all years using the upda ted traffic volumes and emission factors.

Section 2 of this report descri bes the development of the mode l-ready emission inventories. Section 3 describes the CO modeling using UAM and CAL3QHC, and reports the peak 8-hour results from UAM, UAM+CAL3QHC, and UAM+ED MS. Final on-road emission budgets are also reported in Section 3. Section 4 addresse s the requirements of Clean Air Act Section 110(l) concerning changes to local control measures and their potential impacts on reasonable further progress and other pollutants.May 2008



### 2. EMISSION PROCESSING

2.1 OVERVIEW OF APPROACH

The estimation of CO emissions for the CO Maintenance Plan followed the procedures developed for the 2005 CO SIP Revision. Howe ver, updated TransCAD TDM output was used, in parallel to the recent ozone SI P modeling, in addition to new wint ertime fuel specifications. The new wintertime fuel specifications aff ected MOBILE6 on-road emission factors and NONROAD emission estimates. In addition, em issions from Nellis Air Force Base were updated according to the latest information fr om DAQEM. The following future years were simulated: 2008, 2010, and 2020. Note that the or iginal 2006 future year in the 2005 CO SIP Revision was replaced with the 2008 future year in this work.

The revised CO UAM modeling used RTC TransCAD runs that they performed in 2006 to

define on-road mobile source activ ity and distributions, consistent with the ozone SIP modeling. Start and running exhaust emissions were calcula ted and distributed in time and space in the same manner as performed for the CO SIP re vision with modificati ons as necessary to
accommodate the different TAZ definitions in the updated TransCAD model. Although the current I/M program was maintained in all future years, a new fuel was specified for all years comprising a 13.5 RVP with the cu rrent 3.5% oxygenate, with no fu rther fuel controls (no CBG, no TCM adjustments, and no alternative fuel programs for government fleets). EPA's MOBILE6.2 (Air Improvement Reso urce’s version, which allows more detail in the database output to support the processing for this particular approach) was run for all years. Additionally,

Sierra Research's modified version of MOBI LE6.2, which improves the estimate of RVP effects on later model vehicles (Sierra Re search, 2003), was used for all thr ee future years to develop an

alternative set of on-road m obile emissions. The NONROAD2005 model was used to calculate non-road emissions for the new gasoline specifications in all years; this model is also consistent

with the version used in the ozone SIP.

Given that the original 2006 future year in th e 2005 CO SIP Revision wa s replaced with the 2008 future year in this work, stationary CO em issions needed to be generated for 2008. Area emissions were interpolated from the existing 2006 and 2010 inventories and allocated in space using 2006 spatial surrogates. Civil airport and ra ilroad emissions were similarly interpolated. Since point source emissions are held constant for all years, they were used for 2008 without

modification.

2.2 ON-ROAD MOBILE SOURCES

DAQEM provided RTC’s TransCAD model output for each of the future years: 2006, 2008, 2010, and 2020. The TransCAD model output provided link-level volumes (number of vehicles) and trip origins and destinations for the follo wing seven diurnal periods: midnight – 7 AM, 7 AM – 9 AM, 9 AM – 2 PM, 2 PM – 4 PM, 4 PM – 6 PM, 6 PM – 8 PM, 8 PM – midnight. When modeling Sunday, the period data were firs t summed together over all seven periods and then redistributed to hourly va lues using a weekend temporal distribution. When modeling

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### 2-1May 2008



### Monday, the period totals were maintained as output by TransCAD. They were further disaggregated into hourly values by applying th e fraction of each hour within each period from the weekday distribution.

2.2.1 MOBILE6 Inputs

Future year MOBILE6 inputs we re compiled according to the 2005 CO SIP Revision and fuel specifications selected by DAQEM (Table 2-1). For each future year, eight input files were created, for each of the four ro adway types (freeway, arterial, local, and ramp) both for weekday and weekend. For Freeway and Arterial, the model was run for speeds between 5 and 65 mph for every 1 mph increment. The Local roadway type was set at 12.9 mph, and the Ramp roadway type was set to 34.6 mph by MOBILE6 itself.

No CNG fleets were assumed to be present in the future years. The current I/M program was maintained for all future years. Note that MOBILE6 I/M effectiveness was set to 100%; Clark County has developed a white paper to justify this value for Las Vegas (Clark County, 2005). For the VMT mix, values generated from a 2002 traffic study conducted by RTC in Las Vegas (Orth-Rodgers and Associates, 2003) were used, which yielded VMT for 5 vehicle types that were further broken down into 16 vehicle type s based on MOBILE6 default VMT mix for 2002. Clark County does not have future year forecasts for vehicle VMT mix, seasonal/day-of-week adjustments, or hourly activity profiles, so the sa me settings were used for all future years.

Following the approach from the 2005 CO SIP Revision, a first set of MOBILE6 runs was conducted using the start distributi on contained in the sdist.lv file (shown in Figure 2-1). These emission factors were applied to the whole domain except for a small region around Las Vegas

Boulevard. A second set of MOBILE6 runs wa s conducted to better es timate the specific weekday start emission factors al ong the Las Vegas Boulevard (LVB), where the start activity is not centered within residential areas, but rather parking lots near cas inos (and thus are not characteristic of typical commute activity profiles). A more repr esentative start distribution was

calculated as the fractio n of TransCAD origin trips occurr ing over all TAZs along the boulevard from all periods available in the TransCAD output. Figure 2-2 s hows the weekday start distributions for all future years along the Las Vegas Boulevard. Given the similarity of the future year start distributions, th e composite start distri bution was applied to all future years for the region around the Las Vegas Boulevard. Figu re 2-3 compares the hourly MOBILE6 start emission factor profiles for Sunday (en tire domain), Monday (LVB area), and Monday (remainder of the domain).

2.2.2 TransCAD Link Activity Adjustments

The TransCAD volume data is representative of an annual average weekday. The link-level activity was adjusted from annua l average to December by a fact or of 1.000. The activity data were scaled to Sunday estimates by weighting the Sunday day-of-week factor by the average weekday factor. The Sunday activity adjustment was 0.743. Activity was not adjusted for Monday.

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### 2-2May 2008

Table 2-1. MOBILE6.2 input parameters for Las Vegas runs.
M6 Input Parameter Weekday Parameters Weekend Parameters Source

42.0 44.0 49.0 51.0 55.0

58.0 64.0 66.0 66.0 66.0

62.0 58.0 55.0 53.0 51.0

50.0 48.0 47.0 45.0 44.0

44.0 43.0 42.0 42.0 42.0 44.0 49.0 51.0 55.0

58.0 64.0 66.0 66.0 66.0

62.0 58.0 55.0 53.0 51.0

50.0 48.0 47.0 45.0 44.0

44.0 43.0 42.0 42.0 same temperatures
used as in previous work HOURLY TEMPERATURES

REGISTRATION DIST LV_reg02.RDT LV_reg02.RDT provided by Clark County

0.5042 0.0767 0.2552

0.0779 0.0358 0.0080

0.0002 0.0001 0.0003

0.0007 0.0003 0.0000

0.0000 0.0024 0.0011

0.0030 0.0008 0.0007

0.0002 0.0016 0.0025

0.0031 0.0113 0.0072

0.0008 0.0013 0.0019

0.0015 0.5042 0.0767 0.2552

0.0779 0.0358 0.0080

0.0002 0.0001 0.0003

0.0007 0.0003 0.0000

0.0000 0.0024 0.0011

0.0030 0.0008 0.0007

0.0002 0.0016 0.0025

0.0031 0.0113 0.0072

0.0008 0.0013 0.0019

0.0015 provided by Clark County VMT FRACTIONS BY
VEHICLE TYPE

VMT BY HOUR Hvmt_lv.wek Hvmt_lv.wnd provided by Clark County

START DIST sdist.lv sdist.lv provided by Clark County provided by Clark County 0.00 1.00 0.00 0.035 1 0.00 1.00 0.00 0.035 1 OXYGENATED FUELS

83 81 50 22222

22222222 2 11 090.

22212112 83 81 50 22222

22222222 2 11 090.

22212112 provided by Clark County ANTI-TAMP PROG

provided by Clark County > Exhaust I/M program #1

1 1983 2050 1 TRC
2500/IDLE 1 1983 2050 1 TRC
2500/IDLE I/M PROGRAM

I/M MODEL YEARS 1 1968 1995 1 1968 1995
I/M VEHICLES 1 22222 22222222 2 1 22222 22222222 2
I/M STRINGENCY 1 22 1 22
I/M COMPLIANCE 1 90 1 90
I/M WAIVER RATES 1 0.1 0.1 1 0.1 0.1
I/M EFFECTIVENESS 1.00 1.00 1.00 1.00 1.00 1.00
I/M GRACE PERIOD 1 2 1 2
I/M CREDIT FILE tech12.d tech12.d > Exhaust I/M program #2

2 1983 2050 1 TRC
OBD I/M 2 1983 2050 1 TRC
OBD I/M I/M PROGRAM

I/M MODEL YEARS 2 1996 2050 2 1996 2050
I/M VEHICLES 2 22222 22222222 2 2 22222 22222222 2
I/M STRINGENCY 2 22 2 22
I/M COMPLIANCE 2 90 2 90
I/M WAIVER RATES 2 0.1 0.1 2 0.1 0.1
I/M GRACE PERIOD 2 2 2 2 > Evap I/M program #3

3 1983 2050 1 TRC
EVAP OBD 3 1983 2050 1 TRC
EVAP OBD I/M PROGRAM

I/M MODEL YEARS 3 1996 2050 3 1996 2050
I/M VEHICLES 3 22222 11111111 1 3 22222 11111111 1

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### 2-3May 2008

M6 Input Parameter Weekday Parameters Weekend Parameters Source

I/M COMPLIANCE 3 90 3 90
I/M WAIVER RATES 3 0.1 0.1 3 0.1 0.1
I/M GRACE PERIOD 3 2 3 2 2009, 2011, 2021 2009, 2011, 2021 CALENDAR YEAR

1 1 EVALUATION MONTH

no yes WE VEH US

FUEL RVP 13.5 13.5 provided by Clark County

FUEL PROGRAM 1 1 provided by Clark County Average Gasoline Fuel Sulfur Content = 30 ppm Average Gasoline Fuel Sulfur Content = 30 ppm

Maximum Gasoline Fuel Sulfur Content = 80 ppm Maximum Gasoline Fuel Sulfur Content = 80 ppm

DIESEL SULFUR 15,15,15 15,15,15 provided by Clark County

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08

0 4 81 2 1 6 2 0

Hour beginningFraction of Daily Total

2 4 Weekday

Weekend

Figure 2-1. Hourly weekend and weekday start distri butions (fraction) provided by Clark County, used to temporally allocate emissions derived from TransCAD.

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### 2-4May 2008

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

HourFraction of Daily Total Original Starts

2000

2006

2010

2015

2020

2030

Figure 2-2. Fraction of original weekday start distribution (from Figure 2-1) and start distributions in all future years for the Las Vegas Boulevard area calculated from the TransCAD origin trips by TAZ (from the 2005 CO SIP Revision).

0 0.002 0.004 0.006 0.008

0.01 0.012123456789101112131415161718192021222324

Hourg/mile

Mon EF Sun EF LVB Mon EF

Figure 2-3. Hourly start emission factors from the MOBILE6 runs: “Sun EF” is the Sunday profile used for all start emissions; “Mon EF” is the Monday profile used for start emissions

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### 2-5May 2008

outside of the LVB area; and “LVB Mon EF” is the Monday profile used for start emissions within

the LVB area. 

### Prior to calculating the link-based emissions, the link volumes were first adjusted to observed traffic counts by facility type. Then, the adjusted link volumes we re adjusted to bring the total volume into agreement with the VMT reporte d through the Highway Performance Monitoring System (HPMS). The overall HPMS adjustment was a single factor multiplied uniformly to the volumes to bring the total into agreement with HPMS. The HPMS adjustment factor used was 1.0628, based on the ozone SIP work.

Within each of the seven periods, the data were further disaggregated using the default weekday (Dec. 9) distribution for Monday. For Sunday, th e data were summed to obtain the daily total before re-distributing into th e hours using the default weekend (Dec. 8) distribution. The same

VMT distributions that were used for the 2005 CO SIP Revision were used for the future years, as illustrated in Figure 2-4.

After the link data were temporally allocated to hourly values, the hourly speeds were adjusted using the following Bureau of Public Roads (BPR ) curve, where the volume to capacity ratio was capped at 1.25:



# ( ) ⎥ ⎦ ⎤ ⎢ ⎣ ⎡

+ = B ff

a



### C V A S S

*1

where:

S

a = adjusted link speed (mph)

S = reported link free flow speed (mph) ff

V

= total link volume (vehicles OR vehicles per hour)

C = total link capacity (vehicles OR vehicles per hour)

For freeways, interstates, syst em ramps, and expressways,

A = 0.66 B = 7.2

For major arterials, minor arterial s, collectors, ramps, and other,

A = 0.76 B = 5.9



### The link-level emissions were adjusted upward by the factors shown in Table 2-2 to capture transit activity (values provided by DAQEM). Li nk-level emissions were not adjusted for

TCMs.

Table 2-2. Adjustment factor to scale link-level emissions to account for mass transit and traffic

control measures.

Year Transit Adjustment Factor TCM Adjustment Factor

2008 1.004438 1.000

2010 1.003913 1.000

2020 1.003192 1.000

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### 2-6May 2008

On-Road Hourly VMT Distribution

0 1 2 3 4 5 6 7 8

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

HourPercent

Dec. 8 Dec. 9

Figure 2-4. Weekday and Sunday hourly VMT distribution.



### 2.2.3 Link-Level Running Emissions

The TransCAD link level volumes were first adju sted by the count corr ection factor and the HPMS adjustment. Then, they were disaggregat ed to hourly volumes. The speed was adjusted using the hourly volume to capacity ratio in th e BPR curve. The MOBILE6 emission factor for that hour and adjusted speed was multiplied by the hourly link volume to determine hourly emissions. The hourly emissions were further adjusted to December, day of week, transit activity, and TCM’s in CNTLEM within the EPS3 processing. Tables 2-3 through 2-5 present tabulations of VMT by facility t ype for each future year, as directly reported by TransCAD, and after the adjustments described above.

2.2.4 Start Emissions

For Monday, the hourly VMT was estimated by disaggregating the period VMT to hourly VMT using the weekday VMT distributi on show in Figure 2-4. The star t emissions were calculated by

G:\Las Vegas CO MP\TSD\Sec_2_Emissions.doc 

### 2-7May 2008

G: \Las Vegas CO MP\TSD\Sec_2_Emissions.doc 

### 2-8 multiplying the hourly VMT by the hourly MOBILE6 start emission factors. The hourly link

start emissions were then totaled over the entire network and redistributed to TAZ, based on theMay 2008Table 2-3.2008 VMT by facility type. Totals are shown as output byTransCAD, and after seasonal, day-of-week, and public transitadjustments.ModeledGroup CodeFacility Type2006DVMTCountDVMTDVMTDVMTDVMTCorrectionFactorCorrected toCountCorrected toHPMSAdjusted toDecemberAdjusted forTransitSundayMondayDVMTDVMT0External Connector607,7550.9102553,178587,918587,918590,527438,762590,5271System Ramp341,3261.4572497,380528,616528,616530,962394,505530,9622Minor Arterial5,439,1270.97745,316,2035,650,0605,650,0605,675,1354,216,6255,675,1353Major Arterial15,344,9350.946814,528,58415,440,97915,440,97915,509,50711,523,56315,509,5074Freeway on- or off-ramp1,226,8431.06331,304,5031,386,4251,386,4251,392,5781,034,6861,392,5785Interstate10,477,4141.004310,522,46711,183,27811,183,27811,232,9098,346,05211,232,9096Freeway4,567,4261.11695,101,3585,421,7235,421,7235,445,7854,046,2185,445,7857Expressway198,7621.9272383,054407,110407,110408,916303,825408,9168Collector3,310,0841.17423,886,7014,130,7864,130,7864,149,1183,082,7954,149,1189Centroid Connector3,255,2611.17423,822,3274,062,3694,062,3694,080,3983,031,7364,080,39810Local15,2711.174217,93119,05719,05719,14114,22219,14111HOV Lane243,3631.1169271,812288,882288,882290,164215,592290,164Intrazonal106,7381106,738113,442113,442113,94584,661113,945Daily Total45,134,30546,312,23749,220,64549,220,64549,439,08636,733,24149,439,086Transit adjustment1.004438HPMS adjustment1.0628December adjustment1.000Sunday adjustment0.743Monday adjustment1.000G:\Las Vegas CO MP\TSD\Sec_2_Emissions.doc2-9May 2008Table 2-4.2010 VMT by facility type. Totals are shown as output byTransCAD, and after seasonal, day-of-week, and public transitadjustments.ModeledGroup CodeFacility Type2010DVMTCountDVMTDVMTDVMTDVMTCorrectionFactorCorrected toCountCorrected toHPMSAdjusted toDecemberAdjusted forTransitSundayMondayDVMTDVMT0External Connector631,6930.9102574,967611,075611,075613,466455,805613,4661System Ramp356,3401.4572519,259551,868551,868554,028411,642554,0282Minor Arterial6,100,1890.97745,962,3256,336,7596,336,7596,361,5554,726,6356,361,5553Major Arterial16,609,4830.946815,725,85916,713,44316,713,44316,778,84212,466,68016,778,8424Freeway on- or off-ramp1,347,4671.06331,432,7621,522,7391,522,7391,528,6971,135,8221,528,6975Interstate11,303,5661.004311,352,17112,065,08712,065,08712,112,2988,999,43712,112,2986Freeway5,395,3631.11696,026,0816,404,5196,404,5196,429,5804,777,1786,429,5807Expressway193,5981.9272373,103396,534396,534398,085295,777398,0858Collector3,498,2121.17424,107,6014,365,5584,365,5584,382,6413,256,3024,382,6419Centroid Connector3,581,5321.17424,205,4354,469,5374,469,5374,487,0263,333,8604,487,02610Local15,6321.174218,35519,50719,50719,58414,55119,58411HOV Lane486,7521.1169543,654577,795577,795580,056430,982580,056Intrazonal121,4571121,457129,084129,084129,58996,285129,589Daily Total49,641,28450,963,02654,163,50454,163,50454,375,44640,400,95654,375,446Transit adjustment1.003913HPMS adjustment1.0628December adjustment1.000Sunday adjustment0.743Monday adjustment1.000G:\Las Vegas CO MP\TSD\Sec_2_Emissions.doc2-10\Las Vegas CO MP\TSD\Sec_2_Emissions.doc2-1115,72219,802179,890831,439765,7128,889,1851,935,9499,061,7351,381,9125,875,8875,191,09016,742,90670,240,12819,348,898Table 2-5.2020 VMT by facility type. Totals are shown as output byTransCAD, and after seasonal, day-of-week, and public transitadjustments.Group CodeFacility TypeModeled2020DVMTCountCorrectionFactorDVMTCorrected toCountDVMTCorrected toHPMSDVMTAdjusted toDecemberDVMTAdjusted forTransitSundayDVMTMondayDVMT0External Connctor789,0290.9102718,174763,276763,276765,712568,9241System Ramp535,1501.4572779,821828,794828,794831,439617,7592Minor Arterial8,695,6780.97748,499,1559,032,9029,032,9029,061,7356,732,8693Major Arterial19,167,3640.946818,147,66019,287,33319,287,33319,348,89814,376,2314Freeway on- or off-ramp1,707,6641.06331,815,7591,929,7891,929,7891,935,9491,438,4105Interstate15,636,2201.004315,703,45616,689,63316,689,63316,742,90612,439,9796Freeway7,464,6941.11698,337,3178,860,9018,860,9018,889,1856,604,6647Expressway7,6521.927214,74615,67215,67215,72211,6828Collector4,146,4921.17424,868,8115,174,5735,174,5735,191,0903,856,9809Centroid Connector4,693,4891.17425,511,0955,857,1915,857,1915,875,8874,365,78410Local15,8181.174218,57319,73919,73919,80214,71311HOV Lane1,160,4611.11691,296,1191,377,5151,377,5151,381,9121,026,761Intrazonal168,7221168,722179,317179,317179,890133,658Daily Total64,188,43365,879,40970,016,63570,016,63570,240,12852,188,415Transit adjustment1.003192HPMS adjustment1.0628December adjustment1.000Sunday adjustment0.7431.000May 2008G:Monday adjustmentMay 2008



### fraction of period-specific trip origins for each TAZ over the total number of trip origins over all TAZs. For Sunday, the TransCAD data is not repres entative of a typical weekend profile, so the hourly VMT was estimated by first totaling all th e period VMT to a daily value, then it was distributed to hourly values using the weekend pr ofile in Figure 2-4. The Sunday start emissions were then calculated by multiplying the hourly VMT by the MOBILE6 hourly emission factors

for all hours. The emissions were totaled over the entire network and then spatially distributed to each TAZ using a single ratio of the daily total TAZ trip origins to the daily total of all trip origins over the domain.

The future year start emissions were calculate d twice; once using the MOBILE6 emission factors generated using the sdist.lv hourly start distri bution (Figure 2-1), and once using the MOBILE6 emission factors generated using the modified start distribution discussed above to reflect the activity along the Las Vega s Boulevard (Figure 2-2).

Following the methodology in the 2005 CO SIP Re vision, the hourly TAZ start emissions were spatially allocated to the grid cell containing the TAZ centroid a nd the 24 surrounding cells in a “wedding cake” fashion: the grid cell contai ning a TAZ centroid receives 25% of the start emissions from that TAZ, the surrounding 8 grid cells receive 60% of the start emissions (7.5% per cell), and the outside 16 grid cells receive 15% of the star t emissions (0.9375% per cell).

2.2.5 Intrazonal Activity

The intrazonal VMT was calculated assuming a defau lt length of 1 mile for each intrazonal trip (as is described in the 2004-2005 Regional Tr ansportation Plan documentation [FY 2004-2025 RTP and FY 2004-2006 TIP, Chapter 5, page 5-16]).

2.2.6 Total On-Road Emissions

Table 2-6 lists the component and total on-road mobile source emissions for all future years using the AIR version of MOBILE6. For compar ison, Table 2-7 lists the component and total on-road emissions using the Si erra-modified version of MOBI LE6. Figures 2-5 through 2-7 present the future year spatial distribution of the total on-road mobile source emissions for December 9, 1996 using the AIR version of MOBILE6.

The combination of updated TransCAD traffic volumes and higher MOBILE6 emission factors due to fuel changes results in much higher on-road mobile emissions out to 2020 than reported in the 2005 CO SIP Revision. Figure 2-8 displays the 2020 on-road mobile sources from the 2005 CO SIP Revision (compare to Figure 2-7). Figur e 2-9 shows the difference in mobile source emissions between Figures 2-8 and 2-7. Note that higher emission fact ors and higher traffic volumes in the Las Vegas Boulevard and McCarran airport areas result in th e largest increases in

those areas.

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### 2-12May 2008

Table 2-6. Component and total on-road mobile source CO emissions (TPD) for all future years
from the AIR version of MOBILE6.

2008 2010 2020 Sunday 12/8/2005 Links - Running 206.6 204.6 188.9

Starts 157.3 158.8 167.6

Intrazonals 0.7 0.8 0.8

Total 364.6 364.2 357.3 Monday 12/9/2005 Links - Running 277.6 275.1 253.7

Starts 300.6 303.4 319.4

Intrazonals 1.1 1.2 1.3

Total 579.3 579.7 574.4

Table 2-7. Component and total on-road mobile source CO emissions (TPD) for all future years
from the Sierra-modified version of MOBILE6.

2008 2010 2020 Sunday 12/8/2005 Links - Running 167.2 163.7 146.1

Starts 150.3 151.1 158.3

Intrazonals 0.6 0.7 0.7

Total 318.1 315.5 305.1 Monday 12/9/2005 Links - Running 224.3 219.6 195.8

Starts 286.3 287.8 300.5

Intrazonals 1.0 1.0 1.1

Total 511.6 508.4 497.4

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### 2-13May 2008

642 652 662 672 682 692

UTM Easting (km) 3973 3983 3993 4003 4013 4023UTM Northing (km)



### ppm 

## On-Road CO Emissions 2008 Future Year (EPA M6)

0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3

Figure 2-5. Spatial distribution of total on-road mobile source CO emissions on December 9 for the 2008 future year (using AIR version of MOBILE6).

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### 2-14May 2008

642 652 662 672 682 692

UTM Easting (km) 3973 3983 3993 4003 4013 4023UTM Northing (km)



### TPD 

## On-Road CO Emissions 2010 Future Year (EPA M6)

0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3

Figure 2-6. Spatial distribution of total on-road mobile source CO emissions on December 9 for the 2010 future year (using AIR version of MOBILE6).

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### 2-15May 2008

642 652 662 672 682 692

UTM Easting (km) 3973 3983 3993 4003 4013 4023UTM Northing (km)



### TPD 

## On-Road CO Emissions 2020 Future Year (EPA M6)

0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3

Figure 2-7. Spatial distribution of total on-road mobile source CO emissions on December 9 for the 2020 future year (using AIR version of MOBILE6).

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### 2-16May 2008

642 652 662 672 682 692

UTM Easting (km) 3973 3983 3993 4003 4013 4023UTM Northing (km)



### TPD 

## On-Road CO Emissions 2020 Future Year (2005 SIP)

0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3

Figure 2-8. Spatial distribution of total on-road mobile source CO emissions on December 9 for the 2020 future year (taken from the 2005 CO SIP Revision).

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### 2-17May 2008

642 652 662 672 682 692

UTM Easting (km) 3973 3983 3993 4003 4013 4023UTM Northing (km)



### TPD 

## Difference in 2020 On-Road CO Emissions
2008 MP - 2005 SIP

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1



### Max Difference: 1.7 TPD

Figure 2-9. Difference in total on-road mobile source CO emissions on December 9 for the 2020 future year. The field shown in Figure 2-8 is subtracted from the field shown in Figure 2-7.

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### 2-18May 2008



### 2.3 NON-ROAD EMISSION CATEGORIES

2.3.1 Airports

In 2003, Clark County and their contractor Rico ndo and Associates de veloped a detailed emissions inventory at the three county civ il airports (McCarran, North Las Vegas, and Henderson), and performed dispersion modeling using the Federal Aviation Administration’s EDMS model (Ricondo, 2003, 2005). The latest version of EDMS was used, which introduced the AERMOD dispersion model. On-road mob ile sources were estimated using Clark County runs of MOBILE6.2. EDMS was run for 2000, 2005, 2010, 2015 and 2020.

To properly account for the contributions of civil airports toward the valley-wide distribution of CO during the December 8-9 episode, the UAM em issions inventory included the EDMS airport emission estimates. Airport emissions for the 2010 and 2020 future years were taken from the 2005 CO SIP Revision, which in turn were based upon the work of Ricondo (2003, 2005). Emission estimates for 2008 were derived by linea rly interpolating tota l airport emissions

between 2006 and 2010.

The emission estimates for Nellis AFB were upda ted in the current modeling project based on data provided by DAQEM. Table 2-8 shows a nnual total CO emissions reported for Nellis. Emissions for this facility were allocated to each hour of the episode assuming a flat temporal profile (i.e., no monthly, dail y, or hourly variations).

Table 2-8. Annual CO emissions reported for Nellis AFB (TPY).

Year CO (TPY)

2008 1266.03

2010 1305.74

2020 1476.60



### Following the 2005 CO SIP Update, airport emissions were placed evenly acr oss the grid cells in which the airports reside.

2.3.2 Locomotives

The 2005 CO SIP Update included estimates of ra ilroad emissions for 2001 based on the work of Mactec (2003). Switching and line-haul loco motive emissions were allocated to the grid according to the location of yards and railroad line segments, respectively. Projections for 2006, 2010, and 2020 were developed for the 2005 CO SIP Update. Estimates for 2008 were determined by interpolated between 2006 and 2010.

Railroad maintenance emissions were estima ted in the 2005 CO SIP Update using EPA’s NONROAD Model. In this pr oject, railroad equipment emissions for 2010 and 2020 were taken from the previous SIP, and estimates for 2008 were similarly determined by interpolated between

2006 and 2010.

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### 2-19May 2008



### 2.3.3 Other Non-Road Categories

Weekday and weekend emissions for Clark County were estimated using EPA’s NONROAD Model (Core Model Version 2005a, February 2006) for the years 2008, 2010, and 2020. The period type was set to Winter Season, and emi ssions were reported as tons per day. Clark County was modeled as a “Southwest” region inst ead of the default “Central West” region. Table 2-9 summarizes the NONROAD Model input para meters for each future year. All inputs except for the gasoline specifications were taken from the 2005 CO SIP Update.

Table 2-9. Summary of inputs used for NONROAD modeling future years.

2008 2010 2020

Weekday

(tpd) Weekend (tpd) Weekday (tpd) Weekend Weekday Weekend (tpd) (tpd) (tpd)

Period Type Monthly Monthly Monthly Monthly Monthly Monthly

Typical

Day Typical Day Typical Day Typical Day Typical Day Typical Day Summation Type

Year of Episode 2008 2008 2010 2010 2020 2020

Month of Year Dec. Dec. Dec. Dec. Dec. Dec.

Weekend or weekday Weekday Weekend Weekday W eekend Weekday Weekend

Fuel RVP for gas 13.5 13.5 13.5 13.5 13.5 13.5

Oxygen Weight % 3.50 3.50 3.50 3.50 3.50 3.50

Gas sulfur % 0.003 0.003 0.003 0.003 0.003 0.003

Diesel sulfur % 0.0015 0.0015 0.0015 0.0015 0.0015 0.0015

CNG/LPG sulfur % 0.003 0.003 0.003 0.003 0.003 0.003

Minimum temper. (F) 42 42 42 42 42 42

Maximum temper. (F) 66 66 66 66 66 66

Average temper. (F) 51.9 51.9 51.9 51.9 51.9 51.9

Altitude of region low low low low low low



### Airport ground support equipment (GSE) was removed from the NONROAD emissions estimates because they were reported as part of the EDMS (civil airports) and Nellis AFB

inventories. Recreational marine estimates were also removed since the major water areas in Clark County lie outside of the modeling domai n. Railroad maintenance/equipment emissions

were removed from the NONROAD estimates as em issions for this category were taken from the 2005 CO SIP Update.

Figure 2-10 shows the distribution used to temporally allocate non-road sources. Non-road emissions in 2010 and 2020 were allocated to the gr id using surrogates developed specifically for those years from GIS-based landuse datasets as part of the 2005 CO SIP Update. Non-road emissions for 2008 were spatially allocated using the 2006 gridding surrogates from the 2005 CO SIP Update.

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### 2-20May 2008

0 0.02 0.04 0.06 0.08

0.1 0.121357911131517192123

Hour

Figure 2-10. Hourly activity profile used to temporally allocate non-road emissions.



### 2.4 AREA SOURCES

The 2010 and 2020 area source estimates were ta ken from the 2005 CO SIP Update with no changes. Values were interpolated to 2008 from the 2006 and 2010 estimates. Since 2006 and 2010 area sources were spatially a llocated using different gridding surrogates, special processing was required to perform the interpolation to 2008. First, the 2010 area source estimates were processed to the grid using 2006 spatial surrogates. Then 2008 area source estimates were calculated by interpolated between 2006 and 2010 on a cell-by-cell and hour-by-hour basis. Therefore, the 2008 area sources are represented on the grid by 2006 spatial surrogates, similarly

to the non-road sources.

2.5 POINT SOURCES

The point source inventory from the 2000 CO SIP and 2005 SIP Update was used for this modeling. At that time, Clar k County provided a point source emission inventory for future years that included update d stack parameters and emissions based on “Potential To Emit” (PTE) levels for seven specific facilities. The UAM futu re year inventories included PTE levels plus a 70 ton/year buffer for these sources. All future year modeling used the same future year point source data. Table 2-10 shows a breakdown by elevated and low-level point sources.

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### 2-21May 2008

Table 2-10. Modeling CO point source emission estimates (TPD).

Future Years

Elevated 15.53

Low Level 0.28

Total 15.82



### 2.6 SUMMARY OF TOTAL EMISSIONS

Table 2-11 presents a summary of total daily CO emissions by source category, including onroad emissions (based on the AIR version of MOBILE6), for all future years. Figures 2-11 through 2-13 show the spatial distribution of total CO emissions on December 9 for all future

years.

Table 2-11. Summary of total daily CO emissions (TPD) in the UAM CO Maintenance Plan.
On-road mobile emissions are taken from the AIR version of MOBILE6.

2008 2010 2020 Sunday 12/8

On-Road 364.6 364.2 357.3 Henderson Airport 1.5 1.6 2.6 McCarran Airport 30.9 33.2 43.2 North Las Vegas Airport 5.2 5.2 5.5

Nellis AFB 3.5 3.6 4.0

Area Sources 13.6 14.3 18.1

Non-Road 39.9 42.5 49.7

Point Sources 15.8 15.8 15.8

Railroad 0.2 0.2 0.3

Total 475.1 480.6 496.5 Monday 12/9

On-Road 579.3 579.7 574.4 Henderson Airport 1.2 1.3 2.0 McCarran Airport 30.9 33.2 43.2 North Las Vegas Airport 4.1 4.1 4.3

Nellis AFB 3.5 3.6 4.0

Area Sources 13.9 14.7 18.6

Non-Road 57.7 60.8 71.2

Point Sources 15.8 15.8 15.8

Railroad 0.3 0.3 0.4

Total 706.7 713.5 733.9

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### 2-22May 2008

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### TPD 

## Total CO Emissions 2008 Future Year (EPA M6)

0.6 1.2 1.8 2.4 3 3.6 4.2 4.8 5.4 6

Figure 2-11. Spatial distribution of total surface gridded CO emissions on December 9 for the 2008 future year (using AIR version of MOBILE6).

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### 2-23May 2008

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### TPD 

## Total CO Emissions 2010 Future Year (EPA M6)

0.6 1.2 1.8 2.4 3 3.6 4.2 4.8 5.4 6

Figure 2-12. Spatial distribution of total surface gridded CO emissions on December 9 for the 2010 future year (using AIR version of MOBILE6).

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### 2-24May 2008

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### TPD 

## Total CO Emissions 2020 Future Year (EPA M6)

0.6 1.2 1.8 2.4 3 3.6 4.2 4.8 5.4 6

Figure 2-13. Spatial distribution of total surface gridded CO emissions on December 9 for the 2020 future year (using AIR version of MOBILE6).

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### 2-25May 2008

G:\Las Vegas CO MP\TSD\Sec_3_Modeling.doc 

### 3-1 3. MODELING RESULTS

3.1 OVERVIEW OF APPROACH

The UAM was provided with the updated future year CO emission inventories for 2008, 2010, and 2020 (as described in Section 2) and run fo r the December 8-9, 1996 historical CO event. All other environmental parameters were taken from the original modeling as documented in the 2000 CO SIP and the 2005 CO SIP Update. The UAM was used to determine peak 8-hour CO levels in the basin for each future year.

Modeling was performed to address UAM valley-wi de CO distributions, intersection “hot spot” modeling with CAL3QHC, and EDMS micro-sc ale results reported by Ricondo (2003, 2005). With regard to the airports, it was necessary to run UAM twice using two different inventories per future year:

1. Valley-wide CO and micro-scale inters ection modeling – including updated EDMS emissions in the UAM;

2. Micro-scale airport CO mode ling – removing EDMS airport emissions from the UAM inventory in order to minimize double-counting.

EDMS results from the Ricondo (2003, 2005) anal yses were combined with the revised UAM model predictions for the future years of 2008, 2010, and 2020 to estimate 8-hour CO concentrations for the duration of the episode on and around the airport properties. Note that the EDMS results previously reported for 2006 and 2010 (from the 2005 CO SIP Update) were interpolated to derive 2008 EDMS concentrations.

For hotspot intersection modeli ng, the CAL3QHC model was used to model three intersections: Charleston/Eastern, Charleston/Fr emont and Eastern/Fremont, whic h are referred to collectively as the “Five Points” area. EPA (1992, 1995) gui dance for screening level modeling of these

three intersections was followed. The ambient te mperature for each hour of the episode (needed to estimate emissions with the MOBILE6 model) , and the wind direction and speed (needed for the CAL3QHC dispersion estimates) were take n from the original UAM/CAL3QHC modeling

documented in the 2000 SIP. The same MOBILE6 inputs documented for the on-road emissions

calculations in Section 2 were used to estimate emission factor inputs for CAL3QHC. Traffic

volumes for all links associated with the three intersections were scaled according to the

differences between the current TransCAD volumes and those used in the 2005 CO SIP Update.

Since there were no 2008 volumes from the Tr ansCAD results reported in the 2005 CO SIP Update, they were derived by scaling from 2006 (original TransCAD volumes) to 2008 (current TransCAD volumes). The CAL3QHC model out put was added to the background UAM levels to estimate 8-hour CO concentrations for the duration of the episode.

Additional UAM simulations were run with scaled -up on-road CO emissions for each future year to develop on-road mobile emission budgets that demonstrate compliance with the 8-hour CO

standard.May 2008

G:\Las Vegas CO MP\TSD\Sec_3_Modeling.doc 

### 3-2 3.2 UAM SIMULATIONS

The UAM was used to simulate the emissions and transport of carbon monoxide throughout the Las Vegas Valley during the night of December 8-9, 1996 (Sunday-Monday). Specifically, the UAM was run from 1500 LST December 8 to 1100 LST December 9 to cover the most cold, stagnant and stable portion of the episode duri ng which CO was observed to build up. The UAM was run using two sets of emission i nputs, as described in Section 2:

1. On-road mobile sources estimated using the AIR version of MOBILE6;

2. On-road mobile sources estimated using the Sierra-modified version of MOBILE6.

Figures 3-1 through 3-3 display predicted 8-hour maximum CO c oncentrations in the modeling domain using the AIR version of MOBILE6 for the years 2008, 2010, and 2020, respectively. UAM predictions show that the 8-hour CO standard of 9 ppm will not be violated anywhere

within the domain. Three distinct areas of CO maxima occur in the simulation: (1) near the “elbow” of U.S. 95 in northeast Las Vegas; (2) around the intersection of U.S. 95 and I-15; and (3) along the Las Vegas Boulevard “strip” near the intersection with Spring Mountain Road and extending to McCarran airport.

Similar patterns are seen when using emissions derived from the Sierra-modified version of MOBILE6, although the CO concentration patterns ar e lower overall in each year (Figures 3-4 through 3-6). The domain-peak 8-hour CO concen trations are tabulated below for each year and

MOBILE6 run.

Table 3-1. Domain-peak 8-hour CO (ppm) from each UAM simulation.

Peak 8-hour CO

Year AIR MOBILE6 Sierra-modified MOBILE6

2008 8.8 8.4

2010 8.5 8.1

2020 7.7 7.1



### Note that the contribution of Mc Carran airport to local CO concentrations in that area steadily increases over this period. This is due to the projected growth in airpor t activities as reported by Ricondo (2003, 2005). In each successive year through 2020, however, the contribution from on-road mobile sources diminishes, while the pe ak moves from the U.S. 95 “elbow” in northeast Las Vegas to the northern boundary of McCa rran airport along Tr opicana Boulevard.May 2008

G:\Las Vegas CO MP\TSD\Sec_3_Modeling.doc 

### 3-3 642 652 662 672 682 692

UTM Easting (km) 3973 3983 3993 4003 4013 4023UTM Northing (km)



### ppm 

## UAM Max 8-hour CO Concentrations 2008 Future Year (EPA M6)

Peak = 8.8 pp m 5 6 7 8 9 10 11 12

Figure 3-1. Spatial distribution of UAM predicted 8-hour maximum CO concentrations (ppm) for the December 8-9, 1996 episode using emission forecasts for 2008 (AIR version of MOBILE6).May 2008

G:\Las Vegas CO MP\TSD\Sec_3_Modeling.doc 

### 3-4 642 652 662 672 682 692

UTM Easting (km) 3973 3983 3993 4003 4013 4023UTM Northing (km)



### ppm 

## UAM Max 8-hour CO Concentrations 2010 Future Year (EPA M6)

Peak = 8.5 pp m 5 6 7 8 9 10 11 12

Figure 3-2. Spatial distribution of UAM predicted 8-hour maximum CO concentrations (ppm) for the December 8-9, 1996 episode using emission fo recasts for 2010 (AIR version of MOBILE6).May 2008

G:\Las Vegas CO MP\TSD\Sec_3_Modeling.doc 

### 3-5 642 652 662 672 682 692

UTM Easting (km) 3973 3983 3993 4003 4013 4023UTM Northing (km)



### ppm 

## UAM Max 8-hour CO Concentrations 2020 Future Year (EPA M6)

Peak = 7.7 pp m 5 6 7 8 9 10 11 12

Figure 3-3. Spatial distribution of UAM predicted 8-hour maximum CO concentrations (ppm) for the December 8-9, 1996 episode using emission fo recasts for 2020 (AIR version of MOBILE6).May 2008

G:\Las Vegas CO MP\TSD\Sec_3_Modeling.doc 

### 3-6 642 652 662 672 682 692

UTM Easting (km) 3973 3983 3993 4003 4013 4023UTM Northing (km)



### ppm 

## UAM Max 8-hour CO Concentrations 2008 Future Year (Sierra M6)

Peak = 8.4 pp m 5 6 7 8 9 10 11 12

Figure 3-4. Spatial distribution of UAM predicted 8-hour maximum CO concentrations (ppm) for the December 8-9, 1996 episode using emission forecasts for 2008 (Sierra-modified version of MOBILE6).May 2008

G:\Las Vegas CO MP\TSD\Sec_3_Modeling.doc 

### 3-7 642 652 662 672 682 692

UTM Easting (km) 3973 3983 3993 4003 4013 4023UTM Northing (km)



### ppm 

## UAM Max 8-hour CO Concentrations 2010 Future Year (Sierra M6)

Peak = 8.1 pp m 5 6 7 8 9 10 11 12

Figure 3-5. Spatial distribution of UAM predicted 8-hour maximum CO concentrations (ppm) for the December 8-9, 1996 episode using emission forecasts for 2010 (Sierra-modified version of MOBILE6).May 2008

G:\Las Vegas CO MP\TSD\Sec_3_Modeling.doc 

### 3-8 642 652 662 672 682 692

UTM Easting (km) 3973 3983 3993 4003 4013 4023UTM Northing (km)



### ppm 

## UAM Max 8-hour CO Concentrations 2020 Future Year (Sierra M6)

Peak = 7.1 pp m 5 6 7 8 9 10 11 12

Figure 3-6. Spatial distribution of UAM predicted 8-hour maximum CO concentrations (ppm) for the December 8-9, 1996 episode using emission forecasts for 2020 (Sierra-modified version of MOBILE6).May 2008

G:\Las Vegas CO MP\TSD\Sec_3_Modeling.doc 

### 3-9 3.3 MICROSCALE MODELING

Future year UAM simulation results were used to provide estimates of background ambient CO levels for micro-scale modeling performed for the “Five Points” hot spot intersection and for the three civil airports in the modeling domain (McCarran, Henderson Executive, and North Las Vegas). UAM concentrations from the appropr iate grid cells were simply added to the concentrations predicted at each micro-scale receptor to ob tain a total (background + microscale) CO concentration. Note that the UAM si mulations reported here u tilized on-road mobile emissions generated from the AIR version of MOBILE6 only. Procedures for running CAL3QHC and combining with UAM predictions followed the same methodology as described

in the 2000 CO SIP and 2005 CO SIP Revision. Re sults are presented in the following subsections.

3.3.1 CAL3QHC Intersection Modeling

The CAL3QHC model was used to model three intersections: Charleston/Eastern,

Charleston/Fremont and Eastern/Fr emont, which are referred to collectively as the “Five Points” area. The ambient temperature for each hour of the episode (needed to estimate emissions with the MOBILE6 model), and the wind direction and speed (needed for the CAL3QHC dispersion estimates) were taken from the original modeli ng documented in the 2000 SIP. The AIR version of MOBILE6 was used to provide emission fact or inputs for idle and 30 MPH for each hour and each year. Traffic volumes for all links associat ed with the three intersections were scaled according to the differences between the curren t TransCAD volumes and those used in the 2005 CO SIP Update. For 2010 and 2020, scaling factors were developed according to the differences

between the current and 2005 SIP TransCAD volumes averaged over the four UAM grid cells

that contain the Five Points intersections. Since there were no 2008 volumes from the 2005 SIP TransCAD, scaling factors were derived to sc ale from 2006 to 2008 according to the difference between the current 2008 and original 2006 TransC AD volumes. The scaling factors are listed below for each year:

Year CAL3QHC Volume Scaling

2008 1.28

2010 1.19

2020 1.26

The CAL3QHC model output was added to the background UAM levels to estimate 8-hour CO concentrations for the duration of the episode. Table 3-2 presents th e individual peak 8-hour average CO concentrations predicted by UAM, CA L3QHC, and their combination, in each of the future years and for each of the th ree intersections in the “Five Poin ts” area. Note that the peak 8-hour periods among the UAM, CAL3QHC, and UAM+CAL3QHC results occur at different times. All values are well below the 9 ppm standard.May 2008

G:\Las Vegas CO MP\TSD\Sec_3_Modeling.doc 

### 3-10 Table 3-2. Peak 8-hour average CO concentrations (ppm) predicted by UAM, CAL3QHC, and UAM+CAL3QHC for each future year and for each of the Five Points intersections. Note that peaks reported for each of the models and their combined effect occur over different 8-hour periods.

Eastern/Charleston Eastern/Fremont Fremont/Charleston

Year UAM CAL3QHC CAL3QCH+UAM CAL3QHC CAL3QHC+UAM CAL3QHC CAL3QHC+UAM

2008 6.6 2.1 8.1 1.8 7.7 1.0 7.0

2010 6.4 1.9 7.7 1.7 7.4 1.0 6.7

2020 5.8 1.5 6.9 1.4 6.7 0.8 6.0



### 3.3.2 EDMS Airport Modeling

The UAM was run for all future years with exactl y the same inputs as described in Section 3.2; however, airport emissions for the three civil ai rports in the domain were removed from the UAM inventory to minimize double counting to the exte nt possible. It is important to note that traffic volumes on the major roadways within the McCarran airport property are included in both EDMS and TransCAD. As a result, the EDMS +UAM CO concentration results for McCarran reflect a double-counting of porti ons of the on-road mobile source emissions on that property, and so the CO concentrations reported for McCa rran are conservative (i.e., high) estimates.

As part of the 2005 CO SIP Re vision, Clark County provided ED MS simulation results for 2005, 2010, 2015 and 2020, based on the work of Ricondo (2003, 2005). The EDMS results reported for 2006 and 2010 were interpolated to derive 2008 EDMS receptor concentrations. EDMS

concentrations were combined with the UAM model predictions for 2008, 2010, and 2020 to

estimate 8-hour CO concentrations for the dur ation of the episode on and around the airport properties. Note that the receptor grid for Nort h Las Vegas airport was reduced to the immediate area surrounding the airport, and thus results shown in Table 3-3 are lower than reported in the

2005 CO SIP Revision.

In each of these years, several receptors at McCarran airport reported total 8-hour CO concentrations (sum of EDMS and UAM components) above the 8- hour CO standard of 9 ppm. Note, however, that all receptors above the 9 ppm standard in all future years evaluated occurred within areas that are not public ly accessible, as defined by Ricondo (2005). Disregarding any receptors in publicly restricted areas removes all exceedance estimates. Table 3-3 presents the peak total 8-hour CO concentration at all three airports for each future year evaluated. Values for McCarran are taken from the peak publicly acce ssible receptor. All peak CO concentrations are below the 9 ppm standard in all years.

Table 3-3. Peak total UAM + EDMS 8-hour CO concentrations (ppm) at all three airports and for all future years evaluated. Values shown for McCarran airport occur at the peak publicly accessible receptor. Airport 2008 2010 2020
McCarran 7.8 7.7 8.9

Henderson Executive 1.3 1.4 3.0 North Las Vegas 3.5 3.4 2.9May 2008

G:\Las Vegas CO MP\TSD\Sec_3_Modeling.doc 

### 3-11 3.4 ESTIMATING ON-ROAD EMISSION BUDGETS

The UAM was used to refine the estimation of future year on-road mobile CO emission budgets for the central, most urbanized portion of the modeling domain. The definition of the central urban sub-domain is given in Table 3-4 and shown in Figure 3-7. On-road mobile source

emissions calculated from the AIR version of MOBILE6 were scaled up over the entire domain to the point at which the peak 8-hour CO concentration reached 8.9 ppm in each of the future years. Additionally, the on-road mobile source emissions outside the central urban sub-domain

Table 3-4. Grid definition of the central urban sub-domain.

Column Row UTM East UTM North

Low-left 11 19 652.000 3991.000 Upper-Right 36 45 678.000 4018.000

642 652 662 672 682 692

UTM Easting (km ) 3973 3983 3993 4003 4013 4023UTM Northing (km)

Figure 3-7. Location of the central urban sub-domain used in the UAM sensitivity tests (heavy red line).May 2008

G:\Las Vegas CO MP\TSD\Sec_3_Modeling.doc 

### 3-12 were increased by an additional 60% in each year to reach a maximum peak 8-hour CO concentration of just under 9.0 ppm in either the peak UAM grid cell, the peak UAM+ CAL3QHC receptor, or the peak UAM+EDMS receptor. UAM results from this analysis are presented in Table 3-5. Plots of UAM daily maximum CO concentrations for each future year are shown in Figures 3-8 through 3-10.

Table 3-5. Weekday domain-wide on-road emission increase, net on-road emission increase that includes an additional 60% increase outside the central urban sub-domain, resulting UAM predicted peak CO, and resulting total and sub-domain on-road emission budgets (December 9) for each future year.

Year Domain-Wide

On-Road
Emissions

Increase Net On-Road
Emissions

Increase Peak 8-hr CO (ppm) Total Domain

On-Road
Emissions (TPD) Sub-Domain

On-Road
Emissions (TPD)

2008 0.5% 13% 8.87 658 457

2010 4.0% 18% 8.88 686 464

2020 5.0% 23% 8.12 704 435



### Future year CAL3QHC intersection results were similarly scaled up by the domain-wide on-road

emission increases shown in the second column of Table 3-5. Table 3-6 presents the individual peak 8-hour average CO concentrations pred icted by UAM, CAL3QHC, and their combination, in each of the future years and for each of the thre e intersections in the “Five Points” area. Note that the peak 8-hour periods among the UAM, CAL3QHC, and UAM+CAL3QHC results occur

at different times. All values rema in well below the 9 ppm standard.

Table 3-7 presents the peak total UAM + EDMS 8-hour CO concentration from each UAM run listed in Table 3-5 (without airports included). No te that EDMS results were not scaled up as onroad motor vehicle emissions consist of a fractio n of the total EDMS inventory, and much of the on-road emissions on airport property are alread y double counted as described earlier. Values for McCarran are taken from the peak publicly acce ssible receptor. All peak CO concentrations are below the 9 ppm standard in all years.

Table 3-6. Peak 8-hour average CO concentrations (ppm) predicted by UAM, CAL3QHC, and UAM+CAL3QHC for each future year, and for each of the Five Points intersections. UAM and CAL3QHC results are taken from the on-road sensitivity scaling tests. Note that peaks reported for each of the models and their combined effect occur over different 8-hour periods.

Eastern/Charleston Eastern/Fremont Fremont/Charleston Year UAM CAL3QHC CAL3QCH+UAM CAL3QHC CAL3QHC+UAM CAL3QHC CAL3QHC+UAM

2008 6.7 2.1 8.2 1.8 7.8 1.0 7.0

2010 6.7 2.0 8.0 1.8 7.7 1.0 7.0

2020 6.1 1.6 7.2 1.4 7.0 0.8 6.3May 2008

G:\Las Vegas CO MP\TSD\Sec_3_Modeling.doc 

### 3-13 Table 3-7. Peak total UAM + EDMS 8-hour CO concentrations (ppm) at all three airports and for all future years evaluated. Values shown for McCarran airport occur at the peak publicly accessible receptor. UAM results are taken from the on-road sensitivity scaling tests. Airport 2008 2010 2020
McCarran 7.88 7.77 8.98

Henderson Executive 1.38 1.50 3.38 North Las Vegas 3.53 3.51 3.10May 2008

G:\Las Vegas CO MP\TSD\Sec_3_Modeling.doc 

### 3-14 642 652 662 672 682 692

UTM Easting (km) 3973 3983 3993 4003 4013 4023UTM Northing (km)



### ppm 

## UAM Max 8-hour CO Concentrations 2008 Future Year (EPA M6)

Peak = 8.87 pp m 5 6 7 8 9 10 11 12

Figure 3-8. Spatial distribution of UAM predicted 8-hour maximum CO concentrations (ppm) for the December 8-9, 1996 episode using emission forecasts for 2008 with increased on-road mobile source emissions to reach peak CO ju st under 9.0 ppm (AIR version of MOBILE6).May 2008

G:\Las Vegas CO MP\TSD\Sec_3_Modeling.doc 

### 3-15 642 652 662 672 682 692

UTM Easting (km) 3973 3983 3993 4003 4013 4023UTM Northing (km)



### ppm 

## UAM Max 8-hour CO Concentrations 2010 Future Year (EPA M6)

Peak = 8.88 ppm 5 6 7 8 9 10 11 12

Figure 3-9. Spatial distribution of UAM predicted 8-hour maximum CO concentrations (ppm) for the December 8-9, 1996 episode using emission forecasts for 2010 with increased on-road mobile source emissions to reach peak CO ju st under 9.0 ppm (AIR version of MOBILE6).May 2008

G:\Las Vegas CO MP\TSD\Sec_3_Modeling.doc 

### 3-16 642 652 662 672 682 692

UTM Easting (km) 3973 3983 3993 4003 4013 4023UTM Northing (km)



### ppm 

## UAM Max 8-hour CO Concentrations 2020 Future Year (EPA M6)

Peak = 8.12 ppm 5 6 7 8 9 10 11 12

Figure 3-10. Spatial distribution of UAM predicted 8-hour maximum CO concentrations (ppm) for the December 8-9, 1996 episode using emission forecasts for 2020 with increased on-road mobile source emissions to reach peak CO ju st under 9.0 ppm (AIR version of MOBILE6).May 2008

G:\Las Vegas CO MP\TSD\Sec_4_Section110.doc 

### 4-1 4. SECTION 110(l) REQUIREMENTS

Before the EPA can redesignate the Las Vegas Valley nonattainment area to attainment – based on the proposed changes contained in this plan – the provisions of CA AA Section 110(a)(2) and Section 110(l) must be satisfied. Section 110(a)(2) addresses the general requirements for SIPs. Section 110(l) requires that any SIP revision not interfere w ith requirements for attainment or reasonable further progress regarding other cr iteria pollutants, or with any other CAAA requirements. The requirements of Section 110(l) are addressed here.

The maintenance plan proposes to relax one fede rally enforceable control measure – the reduced RVP gasoline program – and removes three ot her control measures: the CBG wintertime program, TCM/TDM, and the Alternative Fuel s Program. However, the TCM/TDM and the Alternative Fuels Program will be retained in th e plan as contingency measures. The following analysis demonstrates that the control measure changes proposed in this CO maintenance plan

will not interfere with Clark C ounty’s progress towards attaini ng the 8-hour ozone NAAQS, or with continued attainment of the PM10 NAAQS. Nevada is currently de signated as attainment/

unclassifiable for PM2.5 under Sect ion 107(d) of the CAAA; theref ore, no analysis is required on PM2.5 NAAQS impacts.

4.1 OZONE

4.1.1 Reduced RVP Gasoline and CBG Wintertime Programs

Relaxation of the RVP for winter time fuels and elimination of the CBG wintertime program are not expected to interfere with attainment of the 8-hour oz one standard because both are wintertime programs. Elevated levels of oz one normally occur during the summertime because heat and sunlight are needed to produce the ch emical reactions between nitrogen oxides (NOx) and volatile organic compounds (VOC ) that form ground-level ozone.

4.1.2 TCM/TDM

CAAA Section 187(b)(2) requires areas classified as serious nonattainme nt to adopt TCMs as provided in Section 182(d)(1). The RTC a dopted Resolutions No. 177 and No. 186 (2000 CO SIP, Appendix D), which indicated support and es tablished the guidelines for administering a voluntary employer-based commuter incentive progr am (VMEP), also known as CAT MATCH.

In 1997, EPA released a policy document that set forth guidance and interpretation on the enforceability of VMEPs (Memo fr om R. Wilson dtd. 10/24/97). It said that state and local agencies “are not responsible, necessarily, fo r implementing a program dependent on voluntary actions” (2000 CO SIP, Appendix A). Furthermore, policy direct s that the total amount of emission reductions from voluntary measures shall not exceed 3 percent of the statutory requirements of the CAAA with respect to any SIP submittal.

DAQEM is evaluating the benefits of VMEPs in conjunction with the development of an ozone SIP; discontinuation of CO SIP credits from the TCM/TDM is not expected to interfere.May 2008

G:\Las Vegas CO MP\TSD\Sec_4_Section110.doc 

### 4-2 4.1.3. Alternative Fuels Program for Government Fleets

The state of Nevada developed the Alternative Fuels Program as a result of the Energy Policy Act of 1992, which required federal, state, and fuel provider fleets to ac quire alternative fuel vehicles. The law establishing this program is set forth in NRS Chapter 486a, which authorizes

the State Environmental Comm ission to promulgate implementing regulations. Those regulations are set forth in NAC Chapter 486a.

DAQEM is evaluating the benefits of the Altern ative Fuel Program in conjunction with the development of an ozone SIP; discontinuation of CO SIP credits from the program is not expected to interfere.

4.2 PARTICULATE MATTER

Relaxation of the RVP requirement for wintertim e fuels, elimination of the CBG wintertime program, and discontinuation of CO SIP credits from the TCM/TDM and the Alternative Fuels Program are not expected to interfere with c ontinued attainment of the 24-hour PM10 standard because DAQEM has demonstrated that motor vehi cle exhaust is an insi gnificant source of PM10 in the Las Vegas Valley (PM10 State Implementation Plan for Clark County, 2001; Milestone Achievement Report for Clark County, 2007).

DAQEM’s determination of source significance was based primarily on the J.D. Smith annual inventory and the 24-hour micro-inventories at five representative sites, supplemented by reviews of the 1998 valley-wide annual emi ssion inventory and Chemical Mass Balance modeling. The emission inventorie s/projections in the Milestone Achievement Report for Clark County (2007) show that motor vehicle exhaust makes an insignificant contribution to PM10

concentrations.

Table 4-1 shows total PM10 mobile source emissions for the Las Vegas Valley in 2006. The

contribution of vehicle exhaust to total PM10 mo bile source emissions is less than 1 percent.

Table 4-1. Total PM 10 Mobile Source Emissions for 2006.

On-Road Mobile Source Category Tons per Day (tpd)

Paved road dust (includes construction and unpaved shoulder track-out) 83.53

Private unpaved roads 9.34

Highway construction projects activities 1.34

Highway construction projects - wind erosion 3.13

Vehicular sulfate PM 0.02

Vehicle tire wear 0.37

Vehicle brake wear 0.55

Vehicle exhaust 0.53

Total PM 10 mobile source emissions 98.81

Source: PM 10 Milestone Achievement Report for Clark County, June 2007.May 2008

G:\Las Vegas CO MP\TSD\Sec_4_Section110.doc 

### 4-3 Table 4-2 shows that mobile source emissi on programs, such as reduced RVP, CBG, TCM/TDM, and alternative fuel fleets, have a negligible effect in reducing 24-hour PM10 concentrations in the Las Vegas Valley.

Table 4-2. 2006 24-Hour Controlled PM 10 Emissions.

On-Road Mobile Source Category Uncontrolled PM 10 (tpd) Controlled PM 10 (tpd) Percent
Reduction

Paved road dust (includes constr uction track-out) 83.53 59.31 29.00

Unpaved road dust 9.34 3.27 65.00

Highway construction projects activities 1.34 0.43 68.00

Highway construction projects–wind erosion 3.13 0.91 71.00

Vehicle sulfate PM 0.02 0.02 0.00

Vehicle tire wear 0.37 0.37 0.00

Vehicle brake wear 0.55 0.55 0.00

Vehicle exhaust 0.53 0.53 0.00

Total 98.81 65.38 33.83%

Source: PM 10 Milestone Achievement Report for Clark County, June 2007.May 2008

G:\Las Vegas CO MP\TSD\References.doc 

### R-1 REFERENCES

Clark County. 2000. “Carbon Monoxide State Implementation Plan: Las Vegas Valley Nonattainment Area, Clark County, Nevada.” Prepared by the Clark County Department of Air Quality and Environmental Management (August 2000).

Clark County. 2005. “Carbon Monoxide State Impl ementation Plan Revision: Las Vegas Valley Nonattainment Area, Clark County, Nevada.” Prepared by the Clark County Department of Air Quality and Environmental Management (October 2005).

Clark County. 2005. “Effectiveness of The Clar k County Vehicle Inspection And Maintenance Program.” Appendix C of the 2005 Carbon Monoxide State Implementation Plan for Clark County. Prepared by the Clark C ounty Department of Air Quality and Environmental Management (October 2005).

EPA. 1992. “Guideline for Modeling Carbon Monoxide from Roadway Intersections,” EPA454/R-92-005, November 1992.

EPA. 1995. User’s Guide to CAL3QHC Ve rsion 2.0: A Modeling Methodology for Predicting Pollutant Concentrations Near Roadway In tersections. EPA-454/R-92-06 (revised), U.S. EPA OAQPS, Research Tria ngle Park, NC. September 1995.

Mactec. 2003. “Clark County-Wide Inventory of Non-road Engine s Project.” Prepared for the Clark County Department of Air Qual ity and Environmental Management.

Orth-Rodgers and Associates, Inc. 2003. “Air Quality Vehicle Distribution Study and Modeling.” Prepared for the Regional Tran sportation Commission of Southern Nevada.

Regional Transportation Commission (RTC). “FY 2004-2025 RTP and FY 2004-2006 (TIP), Chapter 5”, Regional Transportation Commission of Southern Nevada.

Ricondo. 2003. “Carbon Monoxide Emissions I nventory and Dispersion Modeling Study Update 2003.” Prepared for Clark Count y Department of Aviation, by Ricondo & Associates, San Francisco, CA (November, 2003).

Ricondo. 2005. “Addendum to the 2003 Carbon Monoxi de Emissions Inventory and Dispersion Modeling Study.” Memorandum to Dennis Me wshaw, Clark County Department of Aviation, from Adrian Jones, Ricondo & Asso ciates, San Francisco, CA (May 19, 2005).

Sierra Research. 2003. “Review of Current and Future CO Emi ssions from On-Road Vehicles

in Selected Western Areas.” Prepared for Western Stat es Petroleum Association, by Sierra Research, Inc., Report No. SR03-01-01 (January 28, 2003).

UNLV. 2008. http://cber.unlv.edu/pop.html

.