Appendix C – Maintenance Receptors

1 Technical Support Document for EPA’s Proposed Action on the New Mexico’s 2009 Infrastructure State Implementa tion Plan (Transport Portion) for the 2006 24-hour Fine Particulate (PM2.5) Na tional Ambient Air Quality Standard



### Appendix C – Maintenance Receptors

1. EPA Region 9 States – Arizona and California 1. Arizona – Pinal County (Cowtown) 2. Arizona – Santa Cruz County (Nogales) 3. California/Mexico Border – Imperial County
4. Northern California/San Francisco Bay Area – Alameda, Santa Clara, and Solano Counties
5. Northern California – Sacramento County
6. Southern California – Orange, Los Angeles, Riverside, and San Bernardino Counties

2. EPA Region 8 States – Arizona and Utah 1. Utah – Utah County (Provo-Orem) 2. Utah – Salt Lake and Weber Count ies (Greater Salt Lake Area)

Note: See Appendix E for further technical data for Greater Salt Lake Area, Utah.Appendix C – Maintenance Receptors

2 1.1 Arizona – Pinal County (Cowtown)

This monitoring site is a middle scale site and is only comparable to the 24-hour NAAQS due to its close proximity to nearby sources.

Emission inventory data, combined w ith speciation and source apportion ment data, point to agricultural activities and cattle f eedlots, as well as other n earby sources of PM2.5, as primary sources contributing to PM2.5 levels at the Cowtown monitor on days with exceedances of the 24-hour PM2.5 NAAQS. 1

The Cowtown monitor has a consistent PM2.5/PM10 ra tio that is lower than other nearby sites, suggesting that the causes of Cowtown PM2.5 concentra tions are different than for other locations. The correlation of the PM2.5/PM10 ratio with PM2.5 concentr ations at the Cowtown monitor also suggests that PM2.5 and PM10 concentrations at the Cowtown m onitoring site are generated by the same sources. Also, the Cowtown monitor is the only site in the area with a pronounced diurna l pattern, with high PM in the morning and evening hours, further s uggesting the influence of local sources.

EPA believes that, based on the local nature of th e PM2.5 problem, and the distance of the area from New Mexico, it is reasonable to conclude that emi ssions from sources in New Mexico do not interfere with the maintenance of the 24-hour PM2.5 standard at this receptor.

1 Arizona Area Designations for the PM2.5 24-Hour Fine Par ticle National Ambient Air Quality Standards, 2011 (76 FR 6056).Appendix C – Maintenance Receptors

3 Figure 1.1.A: Emission Sources and Design Values within Fifty Miles of the Cowtown MonitorAppendix C – Maintenance Receptors

4 Figure 1.1.B: Cowtown Wind Roses 2

(Note: The different colors in Figure 1.1.B correspond to various levels of PM2.5: Blue is less than or equal to 30 μ g/m3; Yellow is 30-35 μ g/m3; Red is 35-40 μ g/m3; and Black greater than or equal to 40 μ g/m3. Also, values measured between Oc tober-April are shown as triangles, and values measured between May-September are shown as circles.)

1.2 Arizona – Santa Cruz County (Nogales)

The PM2.5 monitoring site in Santa Cruz County is loca ted near the United Stat es border with Mexico. (See Figure 2.2.A: Nogales PM2.5 Nonattainment Area). High PM2.5 values in Nogales generally occur under stagnant, light wind conditions during winter and are associated wi th southerly flow (i.e., from the direction of Mexico). Nighttime drai nage flow is typically from sout h to north along the Nogales Wash and the narrow valley topography can trap air pollutants, especially during the evening hours when the diurnal flow is from the south, out of Nogales, Sonora. 3 Measurements of PM2.5 composition show that the main emission sources are wood burning, food c ooking, open burning, dust emissions, and tailpipe emissions from on-road and off-road vehicles.

EPA believes that, based on the local nature of the PM2.5 problem, the direction of flow during periods of elevated PM2.5, and the distance of the area from New Mexico, it is reasona ble to conclude that emissions from New Mexico do not interfere with the maintenance of the 24-hour PM2.5 standard at this receptor.

2 Technical Support Document for Determination that the Cowtown Monitor is Ineligible for Comparison with the Annual PM2.5 NAAQS, U.S. EPA, Region 9, April 26, 2010.

3 Arizona Area Designations for the PM2.5 24-Hour Fine Par ticle National Ambient Air Quality Standards, 2009 (74 FR 58688).Appendix C – Maintenance Receptors

5 Figure 1.2.A: Nogales PM2.5 Nonattainment AreaAppendix C – Maintenance Receptors

6 1. 3. California/Mexico Border – Imperial County

Levels of PM2.5 in Imperial County that exceed the 2006 24-hour PM2.5 NAAQS are recorded at the
Calexico – Ethel Street monitori ng site, which is located near th e Mexican Border (see Figure 1.3.A, below). The elevated levels of PM2.5 occur primaril y in the wintertime, and fifteen of the eighteen values above the level of 35 μg/m3 in the years 2006-2010 occur in December or January (See Table 1.3.A, below).

The levels of PM2.5 measured at th e Brawley and El Centro monitoring sites are always lower – usually
much lower – than those measured at the Calexico Ethel Street monitor on days when the PM2.5 levels
at the Calexico Ethel St reet monitor exceed 35 μg/m 3 (see Figure 1.3.B, below). Because these nearby
monitors do not show similar increa ses in monitored values, it appears that the cause of elevated PM2.5 appears to be from a local source near the Califor nia/Mexico Border. It is therefore reasonable to
conclude that emissions from sources in New Mexico will not interf ere with the maintenance of the 24-
hour PM2.5 standard at this receptor.Appendix C – Maintenance Receptors

7 Figure 1.3.A: PM2.5 Monitoring Site s in Imperial County, CaliforniaAppendix C – Maintenance Receptors

8 Table 1.3.A: Calexico-Ethel Street: Dates of PM2.5 Values Above 35μg/m 3 for the Years 2006 through 2010

Year Date 2006 January 8, 14, 17, 29 and December 22, 25 2007 November 20, and December 5, 17 2008 January 4, and December 22, 25 2009 September 4, and December 12, 21, 24 2010 June 28, and December 4

Figure 1.3.B: PM2.5 levels (μg/m3) at Imperial County PM2.5 Monitoring Sites from 2006 to 2010, for Days of Elevated PM2.5 0 10 20 30 40 50 60 70 Calexico ‐ Ethel

El Centro

BrawleyAppendix C – Maintenance Receptors

9 1.4. Northern California/San Francisco Bay Area – Alameda, Santa Clara, and Solano Counties

Table 1.4.A: San Francisco Bay Area Ma intenance Receptor Design Values

County ID Design Value (μg/m 3 )

2006-2008 Design Value (μg/m 3 )

2007-2009 Design Value(μg/m 3 )

2008-2010 Alameda 060010007 36 34 30 Santa Clara 060850005 36 34 30 Solano 060950004 36 36 31

The maintenance receptors in the San Francisco Ba y Area, shown in Table 1.4.A and Figure 1.4.A, were only slightly above the standard (1 μg/m 3 above) for the years 2006-2008 and 2007-2009. There is a downward trend in the 24-hour PM2.5 design value at each of the receptors.

The monitored PM2.5 values above 35μg/m 3 likely reflect localized sources because they occur during wintertime temperature inversions with low winds th at persist for several da ys, which allow directly emitted and secondary PM to build up over a few days. 4 Figures 1.4.B and 1.4.C illustrate the wind speed and direction for various le vels of PM2.5, and show that elev ated levels of PM2.5 occur during wintertime conditions with light wind speed. The Ba y Area Air Quality Management District analyses show that during the winter p eak season wood burning can account for 33 to over 80 percent of the
PM2.5 concentrations. Ammonium nitr ate and elemental carbon from diesel sources can also contribute
to elevated PM2.5 concentrations.

During summer, the Pacific high pressure system (Paci fic High) typically strengthens and resides in the northeastern Pacific Ocean, pushing th e jet stream and its attendant st orm systems well to the north of California. In winter, th e Pacific High weakens and shifts sout hward, which allows storm systems to come across central California. As a result, almost all of the Bay Area’s annual precipitation takes place in the November through April period. During the winter rainy periods, i nversions are weak or nonexistent, winds are often moderate and air pollution potential is very low. However, during winter periods when high pressure systems become establis hed over the Bay Area, inversions become strong, winds are light and pollution potential is high. These pe riods are characterized by winds that flow out of the Central Valley into the Bay Ar ea and often include tule fog.

The San Francisco Air Basin encompasses approximately 5,430 square miles and consists of all of Alameda, Contra Costa, Marin, Napa, San Francisco, San Mateo and Santa Clara counties, the southern half of Sonoma County and the southwestern porti on of Solano County. The re gion is characterized by

4 BAAQMD Reports: Sources of Bay Area Fine Particulates ( 2008); Fine Particulate Matter Data Analysis and Modeling in the Bay Area (2009); Evaluation of the Effectiveness and Benefits of the Wood Burning Rule in the San Francisco Bay Area for winter 2009-2010 (2010); Trends in Bay Area Ambient Particulates (2011).Appendix C – Maintenance Receptors

10 complex terrain, consisting of coastal mountain range s, rugged hillsides, and inland valleys and bays. Elevations range from sea level to 1,500 feet.

EPA believes that, based on the local nature of th e PM2.5 problem and the distance of the area from New Mexico, it is reasonable to conclude that emi ssions from sources in New Mexico will not interfere
with the maintenance of the 24-hour PM2.5 standard at these receptors.Appendix C – Maintenance Receptors

11 Figure 1.4.A: San Francisco Bay AreaAppendix C – Maintenance Receptors

12 Figure 1.4.B: Alameda County Pollution Rose for 2005-2007 S W E

2 4 6 8 10 12+
Wind Speed (mph) Site 060011001 San Francisco Bay Area, CA [Alameda County, CA] Pollution Rose, 2005-2007

Year

2004

2005

2006 98th %-ile

27.6

30.4

33.3 # days > 35

. 2

2

Design Value 30-A

2 exceedance(s) not plotted (due to missing or variable wind data) San Francisco Bay Area, CA Meteorological data from 11.8 miles away SAN_JOSE_INTL_AP (ID=23293) 2005

2006

2007 Concentration :
 > 40 μg/m3

 35 - 40 μg/m 3

 30 - 35 μg/m 3

 < 30 μg/m 3

Season : cool (Oct-Apr) warm (May-Sep)Appendix C – Maintenance Receptors

13 Figure 1.4.C: Santa Clara County Pollution Rose for 2005-2007Appendix C – Maintenance Receptors

14 1.5 Northern California – Sacramento County

County Site Name Description

Sacramento Site ID: 060670010 This receptor is in the Sacr amento Metro nonattainment area.

The monitored exceedances likely reflect localized sources occurring during wintertime temperature inversi ons with low winds that persist for several days. The speciation data on days during cold seasons in 2004-2006 with the highest 5 percentile of PM2.5 concentrations show that the mass is 47-60% total car bon mass (TCM), which indicates residential wood burning as a signif icantly contributing source of emissions. ( http://www.epa.gov/pmdesignations/ 2006standards/final/TSD/tsd_F_li mited_2004-06_speciation_data_report.pdf ).

The largest single source of Sacram ento's wintertime PM2.5 emissions is wood and other solid fuel burning in fireplaces, wood inserts, wood stoves and pellet stoves.

There is a strong downward trend in this area in recent years ( http://www.epa.gov/regi on9/air/trends/pm25.html ).

The Northern Sacramento Valley Air Basin is bo unded on the north and west by the Coastal Mountain Range, and on the east by the southern portion of th e Cascade Mountain Range and the northern portion of the Sierra Nevada Mountains. These mountain range s reach heights in excess of 6,000 feet with peaks rising much higher. This provides a substantial physical barrier to locally created pollution.

The maintenance receptor id entified above likely reflects localized sources occurring during wintertime temperature inversions with low wi nds that persist for several days in an area that trap emissions together with complex topography. Th e speciation data from high concen tration days indicates that the PM2.5 has a high carbon mass, which also indicates that residential wood burning emissions are the dominant source. 5 Also, as noted above, the largest singl e source of Sacramento's wintertime PM2.5 emissions is wood and other solid fuel burning in fireplaces, wood inserts, wood stoves and pellet
stoves.

For the area under consideration, high PM2.5 concentr ations mostly occur dur ing stagnant conditions during winter, with radiation invers ions. The cooling of the ground, as he at is radiated away, creates an inversion, since air near the ground is cooler than that above. Th is inhibits mixing and confines pollutants to a relatively shallo w layer near the ground. A typical value for maximum mixing height during high PM2.5 conditions is 300 meters (984 f eet) AGL (above ground level). EPA recognizes that an inversion height is not a rigi d boundary extending through a fixed elevation. In reality the inversion would be partly terrain-following, and the degree of stagnation would be subject to additional influences

5 ARB Almanac website (2006). http://www.arb.ca.gov/ei/maps/statemap/cntymap.htmAppendix C – Maintenance Receptors

15 at the foothill edges, such as st rong diurnal slope flows. In any cas e, mixing heights vary by site and date, so any single height can provide only a scale for comparison, not a definitive value. Nevertheless, the inversion height provides an indicator of the area over which inve rsions may be enhancing pollution concentrations, and of the extent of the area that may interfere with maintenance of the NAAQS. Because these areas in Northern California have t opographical features higher than the typical daytime height of the inversion layer, EPA c onsidered the inversion height to esti mate the size of the area likely to have similar pollution conditions and to interfere with maintenance of the NAAQS.
In summary, topography is an importa nt factor for this area, given th at the inversion layer, which can lead to winter PM2.5 exceedances in the Sacramento Valley, is blocked by the Sierra foothills.
The steep terrain and speciated PM2.5 data at this Northern California re ceptor supports the fact that the PM2.5 is largely of local origin. Ther efore, it is reasonable to conclude that transport from New Mexico does not interfere with maintenance of the 2006 PM2.5 standard at this receptor.

1.6. Southern California – Orange, Los Angeles, Riverside, and San Bernardino Counties

Table 1.4.A: South Coast Air Basin Maintenance Receptor Design Values

County Site Name Description

Orange Anaheim The 2008-2010 design value for this site is 30 μg/m 3 . The previous design values were 38 μg/m 3 in 2006-2008, and 37 μg/m 3 in 2007-2009.

The current design value for the Anaheim site is 30 μg/m 3 , well below the 2006 24-hour PM2.5
standard. The Anaheim site has shown a consistent downward trend over the last ten years. (see Figure 1.6.A: 24-Hour Average PM2.5 Design Concentrati ons 1999-2010). The South Coast Air Quality DRAFT 2012 Air Quality Management Plan air quality projections show that the emission control strategy outlined in the plan will result in air quality improvement at this site. (see Figure 1.6.B: Maximum 24-Hour Average PM2.5 Design Concentr ations: 2008 Baseline, 2014 and 2014 Controlled). Therefore, it is reasonable to conclude that emi ssions from New Mexico will not interfere with the
maintenance of the 24-hour PM2.5 st andard at this receptor.

A more complete discussion of ai r quality in the South Coast Air Basin is included in Appendix B - Non-attainment Receptors at B.1.2.Appendix C – Maintenance Receptors

16 Figure 1.6.A : 24-Hour Average PM2.5 Design Concentrations 1999-2010. 6

Figure 1.6.B: Maximum 24-Hour Average PM2.5 De sign Concentrations: 2008 Baseline, 2014 and
2014 Controlled 7

6 Joe Cassmassi, Item #2, Scientific, Technical & Modeling Peer Review (STMPR) Advisory Group Meeting #1 for 2012 Air Quality Management Plan (AQMP), September 22, 2011. http://aqmd.gov/gb_comit/stmpradvgrp/2012AQMP/meetings/2011/sept22/stmpr01.pdfAppendix C – Maintenance Receptors

17 2.1 Utah – Utah County

(Site ID: 490495008)

A large portion of Utah County is designated as the Provo 2006 PM2.5 nonattainment area (NAA).

The Provo NAA is situated in the Utah Valley. Like th e other low-lying valleys ju st west of the Wasatch Front, the topography of the Utah Valley makes it pr one to temperature invers ions. During inversions, the Provo NAA features stagnant air masses and calm to light winds. As the airshed is essentially capped, PM2.5 is formed in-situ (and trapped) via fr esh locally derived emission sources and secondary chemistry. Transport of air masses between the Salt Lake City and Provo NAAs can occur during inversions, as there is a 4.75-mile gap in the mount ains separating these airs heds which is below the approximate average inversion height for these areas.

Speciation data from exceedance days from 2004-2006 showed the average composition of PM2.5 in Provo is 71% ammonium nitrate, wi th 21% carbon and organic compounds, 8% ammonium sulfate, and 2% crustal.

Several factors, including signi ficant mobile, point and area sour ces contribute to primary and secondarily formed PM2.5 that viol ate the standard during stable weat her events associated with strong inversions.

2.2 Utah – Salt Lake and Weber Counties (Greater Salt Lake Area)

(Site IDs: 490353007 (Salt Lake Co unty) and 490570007 (Weber County))

All of Salt Lake County and a portion of Weber Count y are designated as part of the Salt Lake City (SLC) 2006 PM2.5 nonattainment area (NAA).

The SLC NAA is situated in a valley bordered on the west by the Stansbury Mountains, Promontory Mountains and the Great Salt Lake , and on the east by the Wasatch Front. During inversions, the NAA becomes a closed airshed (save for potential tran sport between the Salt La ke City and Provo NAAs) featuring stagnant air masses and light winds which t ypically oscillate back and forth within the airshed. As the airshed is essentially cappe d during inversions, PM2.5 is formed in-situ (and trapped) via fresh locally derived emission sour ces and secondary chemistry.

Speciation data from exceedance days from 2004-2006 showed the average composition of PM2.5 in Salt Lake City is 58% ammonium nitrate, 31% carbon and organic compounds, 8% ammonium sulfate, and 2% crustal.

Several factors, including signi ficant mobile, point and area sour ces contribute to primary and secondarily formed PM2.5 that viol ate the standard during stable weat her events associated with strong inversions.

7 http://www.aqmd.gov/aqmp/2012aq mp/draft/Chapters/Ch5.pdf