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Template for Technical Support Document

Definition of important terms used in this document:

1) Designated “unclassifiable” – an area where EPA could not determine if there was a 

violation of the 2008 Lead NAAQS or a contribution to a violation in a nearby area, because 

there was insufficient air quality data for both 2006-2008 and 2007-2009 and where additional 

monitoring data for 2010 could not result in a different designation.

2) Designated “attainment” – an area which EPA has determined, based on the most recent 3 

years of certified air quality data from 2006-2008 or 2007-2009, has no violations of the 2008 

Lead NAAQS during 36 consecutive valid 3-month site means; and which EPA has further 

determined does not contribute to a violation of the 2008 Lead NAAQS in a nearby area and that 

additional monitoring data from 2010 could not result in a different designation.

3) Designated nonattainment area – an area which EPA has determined, based on a State 

recommendation and/or on the technical analysis included in this document, has a violation of 

the 2008 Lead NAAQS during the most recent three consecutive years of quality-assured, 

certified air quality data. 

4) Prior nonattainment area – an area that is currently designated as nonattainment or 

maintenance for the 1978 Lead Standard (including both current nonattainment areas and 

maintenance areas).

5) Recommended nonattainment area – an area a State or Tribe has recommended to EPA be 

designated as nonattainment.

6) Violating monitor – an ambient air monitor whose design value exceeds 0.15 micrograms per 

cubic meter (μg/m3). As described in Appendix R of part 50, a violation can be based on either 

Pb-TSP or Pb-PM10 data and only three months of data are necessary to produce a valid violating 

design value. 

7) 1978 Lead NAAQS – 1.5 μg/m3, National Ambient Air Quality Standard for lead

promulgated in 1978. Based on Pb-TSP indicator and averaged over a calendar quarter.

8) 2008 Lead NAAQS - 0.15 μg/m3, National Ambient Air Quality Standard for lead

promulgated in 2008. Based on Pb-TSP indicator and a three-month rolling average. Pb-PM10

data may be used in limited instances, including to show nonattainment.
2

ARIZONA

Area Designations For the

2008 Lead National Ambient Air Quality Standards

The Environmental Protection Agency (EPA) has revised the level of the primary (health-based) 

National Ambient Air Quality Standard (NAAQS) for lead (Pb) from 1.5 micrograms per cubic 

meter (μg/m3) to 0.15 μg/m3 measured as total suspended particles (TSP). EPA has revised the 

secondary (welfare-based) standard to be identical in all respects to the primary standard.

Pursuant to section 107(d) of the Clean Air Act (CAA), EPA must designate as “nonattainment”

those areas that violate the NAAQS and those nearby areas that contribute to violations. The 

table below identifies the portion of counties in Arizona (AZ) that EPA intends to designate

“nonattainment” for the 2008 lead national ambient air quality standard (2008 Lead NAAQS). 

Table 1. Designation Recommendations

Area 

AZ Recommended Nonattainment 

Counties

EPA’s Designated 

Nonattainment Counties

Nonattainment area 

for 1978 Lead NAAQS

Hayden None* Gila County (partial) 

Pinal County (partial)

na

*Governor of Arizona recommended delayed designations. EPA’s recommended boundary is identical to the 

boundary described in ADEQ’s December 2009 Boundary Recommendation Technical Support Document. 

Technical Analysis for Hayden, Arizona and Surrounding Areas

Introduction 

This technical analysis for Hayden, Arizona identifies the monitor that violates the 2008 Lead

NAAQS and evaluates nearby areas for contributions to ambient lead concentrations in the area. 

EPA has evaluated the surrounding area based on the weight of evidence of the following factors 

recommended in previous EPA guidance: 

Air quality in potentially included versus excluded areas;

Emissions and emissions-related data in areas potentially included versus excluded from 

the nonattainment area, including population data, growth rates and patterns and 

emissions controls;

Meteorology (weather/transport patterns);

Geography/topography (mountain ranges or other air basin boundaries);

Jurisdictional boundaries (e.g., counties, air districts, reservations, etc.); and

Any other relevant information submitted to or collected by EPA (e.g., modeling where 

done appropriately).
3

Figure 1 is a map showing the state’s recommended nonattainment area and the surrounding 

counties. Figure 2 shows the lead monitors in the area.

Figure 1. Violating Monitor and Surrounding Area

On December 15, 2009, the Governor of Arizona recommended that all portions of the State, 

excluding Indian Country,1be designated as unclassifiable/attainment for the Pb standard, with 

the exception of the Hayden area of Gila and Pinal Counties, which is violating the standard.

Citing a commitment from the main source of Pb emissions in the area, ASARCO LLC, to 

improve Pb controls on its facility, the Governor requested that EPA delay its designation of the 

Hayden area. If exceedances are recorded between March 2010 – October 2010, or if ASARCO 

fails to agree to enforceable controls, the letter recommends promulgating a nonattainment 

boundary as shown in Figures 1 and 2.2 The basis for the boundary is discussed in Arizona 

Department of Environmental Quality’s (ADEQ’s) boundary recommendation technical support 

document.3

 

1

“Indian country” as defined at 18 U.S.C. 1151 refers to: “(a) all land within the limits of any Indian reservation 

under the jurisdiction of the United States Government, notwithstanding the issuance of any patent, and, including 

rights-of-way running through the reservation, (b) all dependent Indian communities within the borders of the 

United States whether within the original or subsequently acquired territory thereof, and whether within or without 

the limits of a state, and (c) all Indian allotments, the Indian titles to which have not been extinguished, including 

rights-of-way running through the same.”

2 December 2009 Arizona Recommendation

3 ADEQ December 2009 Boundary Recommendation Technical Support Document

*Named sources emitted > 0.05 tpy 

of Pb according to 2005 NEIv2, 2008 TRI, 

and/or ADEQ emissions estimates.

**Unnamed airports emitted < 0.05 tpy 

of Pb according to the draft 2008 NEI.

(draft 2008 NEI)**

Pb Point Source*

 Freeport McMoRan

 BHP Copper

ASARCO Copper Smelter & Concentrator
Copyrighted page/s removed. Copyrighted material is not available in 

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the copyright holder. 

Contact the EPA Docket Center’s Public Reading Room to view 

or receive a copy of this document. 

Requests for copies may be made as follows: 

In person/writing: 

Environmental Protection Agency, Docket Center 

1301 Constitution Ave NW, 2822T, Room 3334 

Washington, DC. 20004 

Telephone: 

202-566-1744 

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202-566- 9744 

Email: 

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5

EPA is not delaying designation of the Hayden area as sufficient data are available to make a 

nonattainment determination at this time.

Based on EPA's technical analysis and currently available information, which is described 

below, EPA intends to designate the Hayden area of Gila and Pinal Counties as nonattainment 

for the 2008 Pb NAAQS.

Air Quality Data 

This factor considers the Pb design values (in μg/m3) for air quality monitors in the Hayden, AZ

area and the surrounding area based on 2006-2008 data. A monitor’s design value indicates 

whether that monitor attains a specified air quality standard. The 2008 Pb NAAQS are met at a 

monitoring site when the identified design value is valid and less than or equal to 0.15 μg/m3. A 

design value is only valid if minimum data completeness criteria are met. A Pb design value that 

meets the NAAQS is generally considered valid if it encompasses 36 consecutive valid 3-month 

site means (specifically for a 3-year calendar period and the two previous months). For this 

purpose, a 3-month site mean is valid if valid data were obtained for at least 75 percent of the 

scheduled monitoring days in the 3-month period. For purposes of assessing data capture, data 

collected before January 1, 2009 will be treated with an assumed scheduled sampling frequency 

of every sixth day, as specified by 40 CFR part 50 Appendix R, section 4(c)(i). A Pb design 

value that does not meet the NAAQS is considered valid if at least one 3-month mean that meets

the same 75 percent requirement is above the NAAQS. That is, a site does not have to monitor 

for three full calendar years in order to have a valid violating design value; a site could monitor 

just three months and still produce a valid (violating) design value.

Pb monitors that collected data in Arizona for all or part of 2006 through 2008 are listed in Table 

2.

As detailed in 40 CFR part 50 Appendix R, all FRM/FEM Pb-TSP and Pb-PM10 data collected in 

accordance with the requirements of 40 CFR part 58, including Appendix A (quality assurance), 

Appendix C (federal reference methods/federal equivalent methods (FRM/FEM)), and Appendix

E (siting criteria), are comparable against the Pb NAAQS. In addition, Pb-TSP and Pb-PM10

data representing sample collection periods prior to January 1, 2009 (i.e., "pre-rule" data) will be 

considered valid for NAAQS comparisons and related attainment/nonattainment determinations 

if the data were submitted to EPA’s Air Quality System (AQS) database prior to September 1, 

2009, and the sampling and analysis methods used to collect the data were consistent with (1) 

previous or newly designated FRMs or FEMs, and (2) the provisions of 40 CFR part 58 that were 

in effect either at the time of original sampling or at the time of the attainment/nonattainment 

determination. 40 CFR part 50, Appendix R contains the requirement for data used for 

comparison with the Pb NAAQS.

In October 2006, EPA Region 9’s Superfund Division began collecting Pb-PM10 monitoring data 

at the Hayden Maintenance Building monitor just west of the ASARCO copper concentrate and 

smelting facility in Hayden, AZ. EPA’s Superfund Division also collected Pb-PM10 monitoring 

data at the Winkelman site, located to the southeast of the ASARCO facility. (See Figure 3.) 
6

Values from July, August, and September 2008 resulted in a 3-month average design value of 

0.17 μg/m3 at the Hayden Maintenance Building monitor. 

EPA has reviewed the quality assurance and quality control documents collected during this 

sampling time. As required by 40 CFR part 58, Appendix A, a quality assurance project plan 

was in place at the time of sampling, as was a field sampling and data management plan. The 

information was entered into AQS in August 2009. Review of calibrations, flow checks, field 

data sheets, chain of custody forms and laboratory reports show data collected at Hayden from 

July through September 2008 to be valid.

Partisol-Plus Model 20205 Sequential Air Samplers were used at both Winkelman and the 

Hayden Maintenance Building sites. At the time, these monitors were designated as EPA PM10

reference method monitors (RFPS-1298-127).4 On June 2, 2009, EPA published a Federal 

Register notice designating these monitors as federal reference monitors for PM Coarse (PM10c).5 

The monitors therefore meet the Federal Reference Method/Federal Equivalent Method 

(FRM/FEM) requirements as specified in 40 CFR part 50, Appendix R. Filters were analyzed 

using Energy Dispersive X-ray Fluorescence Spectroscopy (EDXRF) consistent with EPA 

Compendium Method IO-3.3 and 40 CFR Part 50 Appendix R.

6

The Hayden Maintenance Building monitoring site meets all siting and network design 

requirements specified in 40 CFR 58 Appendices D and E. Located on the roof of a maintenance 

building, the monitor complies with the requirement in 40 CFR 58 App. D 4.5 (i) which states 

that "a monitor must be sited...where the Pb concentrations from all sources combined is

expected to be at its maximum". It is appropriate for the monitor to capture contributions from 

ASARCO as well as any other Pb sources. This site is located in close proximity to a number of 

public residences and is an appropriate location for monitoring ambient air and population 

exposure. 

EPA’s review shows the data collected at the Hayden Maintenance Building between July –

September 2008 to be valid for comparison against the Pb NAAQS.

Values from July, August, and September 2008 resulted in a 3-month average of 0.17 μg/m3 for 

the Hayden Maintenance Building monitor. For 2006-2008, the Winkelman site’s design value 

(highest 3 month average that meets data completeness requirements) is 0.04 μg/m3.

 

4

69624 Federal Register / Vol. 63, No. 242 / Thursday, December 17, 1998 / Notices

5

26395 Federal Register / Vol. 74, No. 104 / Tuesday, June 2, 2009 / Notices

6

66964 Federal Register / Vol. 73, No. 219 / Wednesday, November 12, 2008 / Rules and Regulations
Copyrighted page/s removed. Copyrighted material is not available in 

Regulations.gov since it may not be reproduced without consent of 

the copyright holder. 

Contact the EPA Docket Center’s Public Reading Room to view 

or receive a copy of this document. 

Requests for copies may be made as follows: 

In person/writing: 

Environmental Protection Agency, Docket Center 

1301 Constitution Ave NW, 2822T, Room 3334 

Washington, DC. 20004 

Telephone: 

202-566-1744 

Fax: 

202-566- 9744 

Email: 

docket-customerservice@epa.gov 
8

Table 2. Air Quality Data - Pb monitors in Arizona*

County State

Recommended

Nonattainment?

Monitor Name Monitor Air 

Quality

System ID

Monitor Location Lead Design

Value,

2006 - 2008

(μg/m3)

Gila 

County

No** Hayden 

Maintenance 

Building

04-007-8020-01 2

nd Street and 

Garfield Ave, 

Hayden

0.17

Winkelman High 

School

04-007-8021-01 824 Thorne Ave., 

Winkelman

0.04

FMMI Ridgeline 04-007-0009-01 4030 Linden St, 

Miami

0.07

FMMI Golf 

Course

04-007-8000-01 SR 188 and US 60, 

Globe

0.04

Maricopa 

County

No

JLG Supersite 04-013-9997-01

4530 N. 17th Ave, 

Phoenix 0.01

*Monitors in Bold have the highest 2006-2008 design value in the respective county.

**Governor of Arizona recommended delayed designations. The Hayden and Winkelman monitors fall within the 

boundary described in ADEQ’s December 2009 Boundary Recommendation Technical Support Document. The 

remaining monitors are outside of the boundary.

All five sites in Arizona collected Pb-PM10 data from 2006-2008. The revised 2008 Pb NAAQS 

is 0.15 μg/m3, collected as Pb-TSP. Total suspended particulate (TSP) monitors collect both 

small-sized particles which may be inhaled, as well as larger-sized particles which are too large 

to be inhaled but may affect human health through ingestion. Monitors that collect particulate 

matter of 10 microns and smaller (PM10) capture inhalable-sized lead, but do not capture the 

larger, ingestible lead particles. Ingestion can be a significant Pb exposure pathway, particularly 

for young children, and larger particles may, through weathering or mechanical action, become 

respirable at some point.7 Because what is captured by a PM10 monitor may not account for the 

full Pb-TSP concentration, 40 CFR part 50 Appendix R, section 2(a)(i) specifies that Pb-PM10

data may be used to show nonattainment, but it cannot be used to show attainment. ADEQ is 

also required to install a Pb-TSP monitor near the ASARCO, Hayden smelter.

As shown in Figure 2, the San Carlos Apache tribal lands lie to the east of the recommended 

nonattainment area. There are no Pb ambient air monitors operating within the tribal lands, nor 

do the tribal lands have any sources emitting 0.1 tons per year of Pb or more (see Emissions and 

Emissions-Related Data section below). The Winkelman High School Pb-PM10 monitor is 

located to the east of the sole Pb source located within the nonattainment area (the ASARCO 

copper and smelting facility), and west of the tribal lands. Being a Pb-PM10 monitor, the 

Winkelman monitor does not capture any Pb particles larger than 10 microns that may be present 

in the ambient air. However, its design value of 0.04 μg/m3 is well below the standard. EPA 

does not require Pb-PM10 monitors to be replaced by Pb-TSP monitors until a 3-month mean 

exceeds 0.10 μg/m3.

8

 Available air data therefore indicate that areas to the east of the monitor, 

including the San Carlos Apache tribal lands, are not causing the violation at the Hayden 

Maintenance Building monitor.

 

7

66964 Federal Register / Vol. 73, No. 219 / Wednesday, November 12, 2008 / Rules and Regulations.

8

40 CFR Part 58 Appendix C, section 2.10.2.
9

The Hayden Maintenance Building monitor, sited in Gila County, close to the border of Pinal 

County, is in violation of the 2008 Pb NAAQS. Therefore some portion of Gila County and 

possibly additional areas in surrounding counties must be designated nonattainment. We 

evaluate nearby counties because for each monitor or group of monitors that exceed a standard, 

nonattainment boundaries must cover a large enough area to include not only the area judged to 

be violating the standard but also the source areas that are determined to be contributing to the 

violations. Each area has been evaluated based on the weight of evidence of eight factors and 

other relevant information. 

Emissions and Emissions-Related Data

Evidence of lead emissions sources surrounding a violating monitor are an important factor for 

determining whether a nearby area is contributing to a monitored violation. For this factor, EPA 

evaluated county level emissions data for lead, population data, and emissions controls.

Emissions

Emissions data were derived from the 2005 National Emissions Inventory, version 2 (NEIv2), 

which is the most up-to-date version of the national inventory. See 

http://www.epa.gov/ttnchie1/net/2005inventory.html. EPA recognizes that for certain counties, 

emissions may have changed since 2005. For example, certain large sources of emissions in or 

near this area may have installed emission controls or otherwise significantly reduced emissions 

since 2005. EPA therefore also considered 2008 TRI information for Arizona.9 In addition, 

Arizona provided updated emissions for the ASARCO Hayden smelter.10 Table 3 reflects data 

from the state, the 2005 NEIv2, and the 2008 TRI.

There are approximately 20,000 airport facilities in the U.S. at which leaded aviation gasoline is 

consumed. To evaluate the potential impact of emissions at and near these facilities, EPA 

recommends that States use the draft 2008 NEI. The Arizona airports which emit over 0.10 tons 

per year of Pb according to the draft 2008 NEI are listed in Table 4.

 

9 TRI available at http://www.epa.gov/triexplorer/

10 ADEQ December 2009 Boundary Recommendation Technical Support Document, p 7
10

Table 3. Arizona Facilities with Pb Emissions > 0.10 tpy.*

County

Facility in State 

Recommended 

Nonattainment

Area? Facility Address City

Facility Total 

Air Releases 

(tpy)

Gila No Freeport-McMoRan Miami Inc Hwy 60 And New St. Claypool 4.90

Gila No**

Asarco LLC Ray Complex/ Hayden 

Smelter & Concentrator 640 Asarco Ave Hayden 4.82

Gila No

BHP Coppper Inc Pinto Valley 

Operation

Hwy 60 And Pinto Valley 

Rd Miami 0.13

Cochise No Aacco Cast Products Inc 401 N Aacco Trails Benson 0.23

Greenlee No Freeport-Mcmoran Morenci Inc 4521 Us Hwy 191 Morenci 0.44

Maricopa No

Goodrich Corp Universal 

Propulsion Co 25401 N. Central Ave. Phoenix 0.13

Navajo No Cholla Power Plant 4801 Frontage Rd Joseph City 0.14

*Emissions reflect highest value from ADEQ, 2008 TRI, and 2005 NEI version 2.

**Governor of Arizona recommended delayed designations. Facility falls within the boundary described in ADEQ’s 

December 2009 Boundary Recommendation Technical Support Document.

Table 4. Airports in Arizona Emitting > 0.10 tpy Pb according to the draft 2008 NEI.

County

Airport in State 

Recommended 

Nonattainment

Area?* Facility Type City

Facility Total Air 

Releases (tpy)

Gila No Payson Airport Payson 0.12

Pinal No Casa Grande Muni Airport Casa Grande 0.27

Cochise No Cochise College Airport Douglas 0.13

Cochise No Sierra Vista Muni-Libby AAF Airport

Fort Huachuca Sierra 

Vista 0.11

Coconino No Grand Canyon National Park Airport Grand Canyon 0.29

Coconino No Flagstaff Pulliam Airport Flagstaff 0.11

Maricopa No Phoenix Deer Valley Airport Phoenix 1.35

Maricopa No Falcon Fld Airport Mesa 1.23

Maricopa No Chandler Muni Airport Chandler 0.93

Maricopa No Phoenix-Mesa Gateway Airport Phoenix 0.67

Maricopa No Phoenix Goodyear Airport Goodyear 0.61

Maricopa No Scottsdale Airport Scottsdale 0.50

Maricopa No Glendale Muni Airport Glendale 0.39

Maricopa No Phoenix Sky Harbor Intl Airport Phoenix 0.32

Maricopa No Pleasant Valley Airport Peoria 0.21

Maricopa No Gila Compressor Station Airport Arlington 0.18

Maricopa No Lakeside Airpark Airport Buckeye 0.18

Maricopa No Goldfield Ranch Airport Fountain Hills 0.18

Maricopa No Gila Bend AF Aux Airport Gila Bend 0.18

Maricopa No Luke AFB Airport Glendale 0.18

Maricopa No Mobile Airport Mobile 0.18

Maricopa No Roesner Ranch Airport Morristown 0.18

Maricopa No Paloma Ranch Airport Paloma 0.18

Maricopa No

Airscrew Performance 

Flightpark Ultralight Glendale 0.18

Maricopa No Wickenburg Muni Airport Wickenburg 0.13

Maricopa No Buckeye Muni Airport Buckeye 0.11
11

Maricopa No Stellar Airpark Airport Chandler 0.11

Maricopa No Eagle Roost Airpark Airport Aguila 0.11

Mohave No Grand Canyon West Airport Peach Springs 0.27

Mohave No Kingman Airport Kingman 0.16

Mohave No Lake Havasu City Airport Lake Havasu City 0.14

Pima No Ryan Field Airport Tucson 0.72

Pima No Tucson Intl Airport Tucson 0.44

Pima No Marana Rgnl Airport Tucson 0.25

Yavapai No Ernest A. Love Field Airport Prescott 0.92

Yavapai No Sedona Airport Sedona 0.13

Yuma No Yuma M. C. A. S. Airport Yuma M. C. A. S. 0.16

*Governor of Arizona recommended delayed designations. No airports in Table 4 fall within the boundary 

described in ADEQ’s December 2009 Boundary Recommendation Technical Support Document.

Figure 4 shows airports and point sources in the area near the violating monitor. According to 

the information sources listed above, other than the ASARCO copper smelter there are no 

sources that emit over 0.10 tons of Pb per year within 25 miles of the violating monitor. 

There are no known Pb sources emitting 0.1 tons per year of Pb or greater in the San Carlos 

Apache tribal lands. Without any sources emitting over 0.1 tons per year of Pb, it is unlikely the 

San Carlos Apache tribal lands are causing or contributing to the violation at the Hayden 

Maintenance Building monitor. As discussed in the Air Quality Data section above, data from 

the Winkelman High School monitor supports this conclusion. Air quality and emissions data 

support excluding the San Carlos Apache tribal lands from the nonattainment area.
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Requests for copies may be made as follows: 

In person/writing: 

Environmental Protection Agency, Docket Center 

1301 Constitution Ave NW, 2822T, Room 3334 

Washington, DC. 20004 

Telephone: 

202-566-1744 

Fax: 

202-566- 9744 

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docket-customerservice@epa.gov 
13

Population Data, Growth Rates and Patterns

Table 5 shows the 2008 population and population density for counties in the area. Table 6 

provides projected population growth for towns near Hayden. These data help assess the extent 

to which the concentration of human activities in the area and concentration of populationoriented commercial development may indicate emissions-based activity contributing to elevated 

ambient lead levels. This may include ambient lead contributions from activities that would 

disturb lead that has been deposited on the ground or on other surfaces. Re-entrainment of 

historically deposited lead is not reflected in the emissions inventory.

Table 5. Population Data

County State 

Recommended 

Nonattainment?

2008 

Population

2008

Population 

Density 

(pop/sq mi)

Population 

Change 

2000-2008

Population % 

Change 2000-

2008

Gila No* 52,166 11 807 2

Graham No 36,452 8 2,910 9

Maricopa No 3,954,598 429 857,098 28

Pinal No* 327,301 61 146,025 81

*Governor of Arizona recommended delayed designations. 

Source of data:U.S. Census Bureau estimates for 2008 (http://www.census.gov/popest/datasets.html) and estimation 

of the area of U.S. Counties

While data contained in Table 5 indicates considerable growth in Pinal County from 2000-2008, 

this growth occurred primarily south and west of the Hayden area. ADEQ’s December 2009 

Boundary Recommendation Technical Support Document shows the Hayden area’s population is 

projected to remain between 0-50 people per square mile through 2030.11 As shown in Table 6, 

towns near Hayden are also projected to have little to no growth over the coming years. The 

locations of nearby towns are shown in Figure 5.

Table 6. Historical and Projected Population for Gila and Pinal Counties, and selected towns near Hayden.12

2000 2008 2015 2031

Pinal County 116,397 316,899 486,363 876,091

Gila County 51,335 56,427 61,128 70,358

Globe 7,486 7,603 7,974 8,647

Miami 1,936 1,973 2,022 2,104

Kearny 2,449 2,085 2,630 3,774

Winkelman 443 430 430 430

Hayden 892 860 860 860

Sources: Historical data – U.S. Census Bureau; Projections – Arizona Department of Commerce.

 

11 ADEQ December 2009 Boundary Recommendation Technical Support Document, pp 8-12.

12 ADEQ December 2009 Boundary Recommendation Technical Support Document, p 18.
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or receive a copy of this document. 

Requests for copies may be made as follows: 

In person/writing: 

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Fax: 

202-566- 9744 

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15

Specific to ASARCO, required control measures and technologies are listed in the operating 

permit issued by ADEQ. See ADEQ’s December 2009 Boundary Recommendation Technical 

Support Document for more details.

Meteorology (weather/transport patterns)

Due to the constraints imposed by the complex terrain in the Hayden area (see 

Geography/Topography factor), the extent of the area exceeding the Pb standard is confined to a 

relatively small area around the main source of lead emissions, the ASARCO Hayden smelter. 

For the same reason, locations outside the particular valleys intersecting at Hayden do not 

contribute to NAAQS exceedances there. Therefore, the meteorology factor did not play a 

significant role in determining a boundary for the nonattainment area.

Meteorological data is available from the very nearby Winkelman 6 S station, part of the 

National Weather Service Cooperative Observer Program. There is typically only 14 inches of 

rain each year, with nearly half occurring July through September, coinciding with the Arizona 

"monsoon" season. There is less than an inch of snow each year. Daily temperature highs range 

from 64 to 91°F depending on season, and lows range from 31 to 69°F.

General wind information for Gila County is presented in Figure 6. Varied elevations in and 

around Hayden cause complex local wind flow. Within and adjacent to the Gila River and San 

Pedro River valleys, drainage winds tend to dominate at night under stable conditions, toward the 

west on the south and west side of the smelter, and toward the south on the east side of the 

facility. These conditions cause air pooling in low-lying areas at night, causing pollutants within 

the air to settle in these areas. During the day under convective conditions, good vertical mixing 

causes polluted air to reach the ground. The vertical mixing also causes the flow to be coupled 

with winds aloft, which generally flow toward the east.

ADEQ's boundary recommendation technical support document further describes wintertime 

conditions.

During the wintertime, relatively strong inversions (where cold air becomes trapped at 

the surface by warmer air aloft) create extremely stable atmospheric conditions. 

Depending on the strength of the inversion and amount of daytime surface heating, the 

inversion may break by the early afternoon, permitting the air to mix vertically. 

Sometimes, however, the inversion may not break at all. Under these conditions, vertical 

and horizontal movement of the air is very limited, causing pollutants in the air to 

accumulate up to several days with little dispersion.13

As described in the Geography and Topography factor below, Hayden's complex terrain limits 

the extent of the area exceeding or contributing to the violation.

 

13 ADEQ December 2009 Boundary Recommendation Technical Support Document, p 21.
16

Figure 6. Average Wind Direction Frequencies in Gila County, AZ.

Source: A three-dimensional bar chart shows the wind frequencies in eight directions for the four seasons. This data 

is taken from 1960-1992 Solar and Meteorological Surface Observation Network information issued jointly by the 

U.S. Department of Commerce: National Climatic Data Center and the U.S. Department of Energy: National 

Renewable Energy Laboratory. The chart frequencies reflect the directions from which the winds come.

Geography/topography (mountain ranges or other air basin boundaries)

The geography/topography analysis evaluates the physical features of the land that might have an 

effect on the air shed and, therefore, on the distribution of lead over Hayden, Arizona. As shown 

in Figure 7, the ASARCO Hayden smelter is located in very complex terrain, with the Gila River 

making a winding semi-circle south of the facility, and intersected by the San Pedro River valley 

from the south. The facility itself is elevated relative to the valleys; there is a 200 foot hill just 

south of the facility, and mountains rising toward the north/northeast. ADEQ's boundary 

recommendation technical support document contains the following terrain description.

Hayden lies in the Gila River Valley, approximately 2,044 feet above sea level. The town sits 

at the base of the Dripping Springs Mountains which rise to a height of approximately 5,096 

feet. The Mescal and Pinal Mountain ranges rise to the east beyond the Dripping Springs 

range to approximately 7,848 feet in elevation at the highest point. To the west of Hayden, 

the Tortilla Mountains rise to a height of 4,273 feet. The complex terrain forms natural 

boundaries that isolate the Hayden area from most of Gila and Pinal Counties.

14

In all directions there is a mountain side, limiting the extent of the area exceeding the Pb 

standard to a relatively small area around the smelter, the main source of Pb emissions. For the 

same reason, locations outside the particular valleys intersecting at Hayden do not contribute to 

NAAQS exceedances there. This supports a relatively small nonattainment area, comprising the 

nearby valleys and mountains, and including a buffer zone.

 

14 ADEQ December 2009 Boundary Recommendation Technical Support Document, p 21.
Copyrighted page/s removed. Copyrighted material is not available in 

Regulations.gov since it may not be reproduced without consent of 

the copyright holder. 

Contact the EPA Docket Center’s Public Reading Room to view 

or receive a copy of this document. 

Requests for copies may be made as follows: 

In person/writing: 

Environmental Protection Agency, Docket Center 

1301 Constitution Ave NW, 2822T, Room 3334 

Washington, DC. 20004 

Telephone: 

202-566-1744 

Fax: 

202-566- 9744 

Email: 

docket-customerservice@epa.gov 
18

ADEQ has overall jurisdiction over environmental programs in the state of Arizona, as well as 

jurisdiction over certain source types, including smelters, refineries, and coal-fired power plants, 

and retains authority for regulating emissions from agricultural operations. Three Arizona 

counties, Maricopa, Pima, and Pinal, have their own air pollution control programs and operate 

pursuant to agreements with ADEQ. The lead air quality planning agencies responsible for state 

implementation plans (SIPs) for Maricopa County and Pima County are the metropolitan 

planning organizations (MPO), the Maricopa Association of Governments (MAG) and the Pima 

Association of Governments (PAG), respectively. There is no MPO and thus no air quality 

planning agency for SIP purposes in Pinal County or Gila County. Therefore, ADEQ is 

responsible for developing SIPs for these counties. 

As shown in Figure 8, the San Carlos Apache tribal lands lie to the east of the recommended 

nonattainment area in both Pinal County and Gila County. Neither ADEQ nor the counties have 

jurisdiction over tribal lands. 

With the exception of the eastern boundary, the intended Pb nonattainment area boundary 

coincides with that of the existing Hayden SO2 nonattainment area15. Arizona recommended 

excluding Indian Country from the nonattainment area, as the state has no jurisdiction over 

Indian lands.16 As discussed in previous sections of this document, the Winkleman monitor, 

located just east of Hayden and west of the San Carlos Apache tribal lands, has a design value of 

0.04 μg/m3, well below the standard. There are no known Pb sources emitting 0.1 tons per year 

of Pb or greater in the San Carlos Apache tribal lands. Given the air quality data, lack of 

sources, the low monitored concentrations, and the state's lack of jurisdiction, EPA supports 

excluding the San Carlos Apache tribal lands from the recommended Hayden Pb nonattainment 

area.

 

15 44 FR 21261, April 10, 1979

16 ADEQ December 2009 Boundary Recommendation Technical Support Document, p 2
Copyrighted page/s removed. Copyrighted material is not available in 

Regulations.gov since it may not be reproduced without consent of 

the copyright holder. 

Contact the EPA Docket Center’s Public Reading Room to view 

or receive a copy of this document. 

Requests for copies may be made as follows: 

In person/writing: 

Environmental Protection Agency, Docket Center 

1301 Constitution Ave NW, 2822T, Room 3334 

Washington, DC. 20004 

Telephone: 

202-566-1744 

Fax: 

202-566- 9744 

Email: 

docket-customerservice@epa.gov 
20

Other Relevant Information

See ADEQ’s submittal documents for further details.

Conclusion

After considering the factors described above, EPA believes it is appropriate to include the 

Hayden portions of Gila and Pinal Counties in the Hayden 2008 Pb NAAQS nonattainment area. 

The Hayden Maintenance Building air quality monitor near the ASARCO copper smelting and 

concentrate facility in Gila County shows a violation of the 2008 Pb NAAQS, based on 2006-

2008 air quality data. All other Pb monitors in Arizona currently attain the standard, including 

those north and east of the violating monitor. Given the heavy weight of Pb, emissions are not 

expected to transport long distances. Instead, Pb emissions fall out of the atmosphere relatively 

close to their emission point. The topography and geography of the Hayden area further support 

the boundaries identified by the state. Based on its consideration of all the relevant, available 

information, as described above, EPA believe that the boundaries described herein encompass 

the entire area that does not meet (or that contributes to ambient air quality in a nearby area that 

does not meet) the 2008 Pb NAAQS.
21

Citations

December 2009 Arizona Recommendation

Letter from Janice K. Brewer, Governor, to Laura Yoshii, U.S. Environmental Protection 

Agency Region 9, December 15, 2009 transmitting recommendations for the 2008 Pb NAAQS, 

with enclosures.

ADEQ December 2009 Boundary Recommendation Technical Support Document

“Arizona Air Quality Designations Technical Support Document: Boundary Recommendation 

for the 2008 Revision to the National Ambient Air Quality Standard for Lead,” Air Quality 

Division, Arizona Department of Environmental Quality, December 9, 2009.

References

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CH2M Hill. November 2005. Final Field Sampling Plan, ASARCO LLC Hayden Plant Site, 

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for CH2M Hill.

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22

Monthly Quality Control Maintenance Check Sheets, Hayden, AZ monitor. November 2006 –

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Yoshimura, Gwen. November 30, 2009. Completeness Calculation, Hayden Maintenance 

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