# Gila River Indian Community Department of Environmental Quality Air Quality Program

2006

TRIBAL AMBIENT AIR MONITORING NETWORK REVIEW

Gila River Indian DEQ Air Program 35 Pima Street, PO Box 97 Sacaton, AZ 85247GRIC DEQ Page ii 10/17/2007



### EXECUTIVE SUMMARY

An inherent function of tribal government is th e responsibility to control the use of natural resources, environmental protecti on and public health on tr ibal lands. The quality of ambient air as well as the manner in which it is protected is extremely important to the health and economic well-being of the Gila River Indian Community (GRIC or Community). Congress recognized these principles in Sections 110(o) and 310(d) of the Clean Air Act (CAA). EPA stated its intention to achieve these principles in its November 8, 1984 and March 14, 1994 memoranda in which the agency set out its pol icy governing administration of environmental programs on tribal lands. More directly, EPA regulations at 40 CFR Part 49 establish the mechanisms for exercising tribal CAA authority. The structure of those mechanisms is based upon a general recognition that tribes have inhe rent authority over ai r resources within th e exterior boundaries of reservations. See generally 63 Fed. Reg. 7253-7271, February 12, 1998; 59 Fed Reg. 43956- 43979, August 25, 1994.

The Code of Federal Regulations, Title 40, Part 58 (40 CFR Part 58) contains the United States Environmental Protection Agency's (USEPA) am bient air quality surveillance regulations. Section 58.10 calls for air monitoring agencies to establish air quality surveillance systems. The air quality surveillance system consists of a netw ork of monitoring stations designated as State and Local Air Monitoring Stations (SLAMS), wh ich measure ambient concentrations of those pollutants for which standards have been estab lished in 40 CFR Part 50. GRIC Department of Environmental Quality (DEQ) will utilize the pr otocols established under the SLAMS air quality surveillance systems described in 40 CFR Part 58.

SLAMS must meet the requirements of 40 CF R Part 58, Appendices A (Quality Assurance Requirements), C (Ambient Air Quality Monitori ng Methodology), D (Netwo rk Design Criteria) and E (Probe and Path Siting Criteria).

Conformance with Appendices A and C is determ ined in part by conducting periodic systems and performance audits required by Section 2.4 of Appendix A. Conformance with Appendices D and E is achieved by monitoring agencies conduc ting an annual network review of their air quality surveillance systems, which is stated in 40 CFR 58.10(d).

The annual network review determines if an am bient air quality monitoring network is achieving its required air monitoring objectives, and identif ies modifications to the network which will enable an organization to meet those objectiv es. An effective ambient air quality monitoring network collects adequate, representative, and usef ul data. The air quality data collected by the Gila River Indian Community Department of Environmental Quality (GRIC DEQ) monitoring network is used for a variety of purposes incl uding: determining compliance with the national ambient air quality standards (NAAQS), determin ing maximum pollutant concentrations, the effectiveness of air pollution c ontrol programs, evaluating the e ffects of air pollution on publicGRIC DEQ Page iii 10/17/2007

health, supporting dispersion models, developi ng responsible and co st-effective pollution control strategies and dete rmining air quality trends.

This document identifies modifications to DE Q’s ambient air monitoring network. DEQ’s ambient air quality monitoring needs, goals and priorities are also included.GRIC DEQ Page iv 10/17/2007

TABLE OF CONTENTS

Section Page

1.0 Introduction............................................................................................................. 1 2.0 Ambient Air Quality Monitoring Requirements and Other Data Needs................ 2 2.1 Appendix D ........................................................................................... 2 2.1.1 Monitoring Objectives and Spatial Scales...................................... 2 2.1.2 Number of SLAMS Sites................................................................ 3 2.2 Appendix E Requirements ......................................................................... 3 2.3 Other Ambient Air Monitoring Needs........................................................ 4 3.0 Network Review Procedure.................................................................................... 5 3.1 Network Review Team and Preparation..................................................... 5 3.2 Network Modifications............................................................................... 5 3.3 Determining Conformance with Appendix D and Special Monitoring Requirements.............................................................. 5 3.3.1 Number and Location of Monitors................................................. 6 4.0 Network Evaluation and Recommendations........................................................... 7 4.1 Ozone................................................................................................... 7 4.2 PM10.................................................................................................. 9 4.3 Other PM10 Monitoring........................................................... 10 5.0 References............................................................................................................... 1 2 6.0 Appendix ................................................................................................................ 1 3 A GRIC Ambient Air Monitoring Data........................................................... 14

List of Tables................................................................................................................. ...... iv

LIST OF TABLES

Number Page

2-1 Relationship Among Monitoring Objectives and Scales of Representativeness................................................................................... 7 2-2 Summary of Spatial Scales for SL AMS and Required Scales for NAMS.............. 7 2-3 Summary of Probe and Monito ring Path Siting Criteria......................................... 8 A-1 Sacaton and St Johns Ozone Data, 1 Hour Averages ............................................ 14 A-2 Sacaton and St Johns Ozone Data, 8 Hour Averages ............................................ 14 A-3 Casa Blanca PM10 Data, 24 Hour Averages ...................................................... 15GRIC DEQ Page 1 12/4/2007



### 1.0 Introduction

The Code of Federal Regulations, Title 40, Part 58 (40 CFR Part 58) contains the EPA’s ambient air quality surveillance regulations. Section 58.10 calls for air monitoring agencies to establish air quality surveillance systems in their Implem entation Plans. The air quality surveillance system consists of a network of monitoring stations designated as SLAMS, which measure ambient concentrations of those pollutants for wh ich standards have been established in 40 CFR Part 50. SLAMS must meet the requirement s of 40 CFR Part 58, Appendices A (Quality Assurance Requirements), C (Ambient Air Qu ality Monitoring Methodology), D (Network Design Criteria) and E (Probe a nd Path Siting Criteria). Conformance with Appendices A and C is determined in part by conducting periodic syst ems and performance audits required by Section 2.4 of Appendix A. Conformance with Appendices D and E is achieved by air monitoring agencies conducting an annual review of their air quality surveillan ce systems, which is required by 40 CFR 58.10(d).

The annual network review determines if th e network achieved its required air monitoring objectives, and if it should be modified (e.g. termination, relocation or establishment of monitoring stations) to meet those objectives. The main purpose of this review is to ensure that an ambient air quality monitoring network collec ts adequate, representa tive, and useful air quality data. The ambient air quality data from the Gila River Indian Community Department of Environmental Quality (GRIC DEQ) network is used for a variety of purposes including:

• determining compliance with the national ambient air quality standards (NAAQS),

• determining the location of maxi mum pollutant concentrations,

• determining the effectiveness of air pollution control programs,

• evaluating the effects of ai r pollution on public health,

• supporting dispersion models,

• developing responsible, cost-e ffective control strategies,

• developing air quality trends.GRIC DEQ Page 2 10/17/2007



### 2.0 Ambient Air Quality Monitoring Re quirements and Other Data Needs

2.1 Appendix D

Appendix D of 40 CFR 58 describe s concepts for designing SL AMS network. It addresses monitoring objectives, and the cr iteria for selecting the locati on and number of air monitoring stations. The concepts and gui dance in Appendix D, as well as other non-regulatory EPA data needs, should be considered when evalua ting the adequacy of the SLAMS network.

2.1.1 Monitoring Objectives and Spatial Scales

Appendix D calls for the design of SLAMS netw orks to meet a minimum of three basic objectives:

(1) Provide air pollution data to the general public in a timely manner. (2) Support compliance with ambient air quality standards and emissions strategy development. (3) Support for air pollution research studies.

SLAMS networks are designed to provide data for meeting the monitoring objectives described above and to assist the EPA and air monitoring agencies in solving environmental problems.

Appendix D also provides guidan ce on spatial scales of represen tativeness for stations in a SLAMS network (Table 2-1). Ideally, the monitor is located so that its sample represents the air quality over the entire area that the monito ring station is intended to represent.GRIC DEQ Page 3 10/17/2007

Table 2-1. Relationship Between Site Types and Scale of Representativeness

Monitoring Objectives Appropriate Siting Scales

Highest concentration Micro, middle, neighborhood, urban Population Neighborhood, urban Source impact Micro, middle, neighborhood General/Background and Regional trans port Neighborhood, urban, regional Welfare-related impacts Urban/regional

Table 2-2. Summary of Spatial Scales for SLAMS

Scales Applicable for SLAMS

Scales O 3 PM 10

Micro.............. 9

Middle............ 9 9 Neighborhood 9 9

Urban.............. 9 9 Regional......... 9 9

2.1.2 General Monitoring Requirements

Appendix D to 40 CFR Part 58 doe s not contain criteria for determining the total number of stations in the SLAMS network. Factors su ch as topography, source type, proximity and locations of nearby populations may affect the num ber of stations in the network. Other than these requirements, the optimum size of a par ticular SLAMS network involves tradeoffs between data needs and available resources which can best be resolved during the network design

process.

2.2 Appendix E Requirements

Appendix E contains siting criteria to be applied to ambient air quality analyzers or samplers after the general site location has been select ed based on the monitori ng objectives and spatial scales of representativeness pr esented in Appendix D and summa rized in Section 2.1 of this document. The siting criteria presented in Appendix E are summarized in Table 2-6.

EPA believes that most sampling probes or monito rs can be located so that they meet the Appendix E siting requirements. Some existi ng stations, however, may not meet these requirements and yet still produce useful data for some purposes. EPA will consider written requests from the State/Tribes to waive one or mo re siting criteria for some monitoring stationsGRIC DEQ Page 4 10/17/2007

provided that the State/Tribe can demonstrate the following: (1) the site is as representative of the monitoring area as it would be if siting criteria were met; and (2) the siting criteria cannot be met because of physical constraints (e.g., inabilit y to locate the stati on the necessary setback distance from roadways or obstructions). Waiv ers may be granted to existing SLAMS if one of these criteria is met; waivers may be granted for new SLAMS only if both criteria are met. Written requests for waivers must be submitted to the EPA Regional Administrator.

2.3 Other Ambient Air Monitoring Data Needs

GRIC has a number of special purpose monito rs (SPMs) deployed throughout the Community for PM 10 . They are used for a variety of purposes, including ambient air quality assessment and special studies such as the Joint Air Toxics A ssessment Project. SPM monitoring sites often utilize Federal Reference Method (FRM) and Federal Equivalent Method (FEM) sampling equipments, and are operated in accordance with CFR requirements for quality assurance and quality control. SPM designation for criteria pol lutant monitoring sites allows GRIC DEQ to assess ambient particulate levels within re gions of the Communit y, while providing the flexibility to relocate the sites if it is determined there is no co ncern for NAAQS violations in the area (typically after three years of data collec tion). SPM sites may be added to GRIC DEQ’s network when elevated pollutant concentrations are consistently measured at the site.

Table 2-3. Summary of Probe and Monitoring Path Siting Criteria

Pollutant Scale [maximum monitoring path length, meters] Height from ground to probe or 80% of monitoring path a (meters) Horizontal and vertical distance from supporting

structures b,g to probe or 90% of monitoring path a (meters) Distance from trees to probe or 90% of monitoring path a (meters) Distance from roadways to probe or monitoring path a (meters)

O 3 c,d,e Middle [300m] Neighborhood and Regional [1km] 3-15 >1 >10 See Table 1 h for all scales.

PM 10 c,d,e,f Micro; Middle, Neighborhood, and Regional 2-7 (Micro); 2-15 (All other scales). >2 (All scales, horizontal distance only). >10 (All scales) 2-10 (Micro); See Figure 2 h for all other scales.

a Monitoring path for open path analyzers is applicable only to middle or neighborhood s cale CO monitoring and all applicable sca les for monitoring O 3 . b When probe is located on a rooftop, this separation distance is in reference to walls, parapets , or penthouses located on roof.

c Should be >20 meters from the dripline of tree(s) and must be 10 meters from the dripline when the tree(s) act as an obstructio n. d Distance from sampler, probe, or 90% of monitoring path to obstacl e, such as a building, must be at least twice the height the obstacle protrudes above the sampler, probe, or mon itoring path. Sites not meeting this crite rion may be classified as middle scale.

e Must have unrestricted airflow 270 ° around the probe or sampler; 180 ° if the probe is on the side of a building.

f The probe, sampler, or monitoring path shoul d be away from minor sources, such as furnace or incineration flues. The separatio n distance is dependent on the height of the minor source’s emissi on point, the type of fuel or waste burned, and the quality of the fuel. This criterion is designed to avoid un due influences from minor sources.

g For collocated PM 10 samplers, a 2-4 meter separation distance between collocated samplers must be met.

h Tables and figures are in A ppendix E of 40 CFR Part 58.GRIC DEQ Page 5 10/17/2007



### 3.0 Network Review Procedure

3.1 Network Review Team and Preparation

Network review participants in clude GRIC DEQ Air Monitoring st aff and representatives from USEPA Region 9 Technical Support Program. Depending on available resources, network reviews may be conducted on, or off-site. In eith er case, sufficient inform ation must be provided to determine conformance of the network with regulatory network design and siting requirements specified in 40 CFR Part 58, Appendices D and E as well as to determine conformance of the network design and siting requirements specified fo r all special ambient air monitoring networks.

3.2 Network Modifications

Modifications to the SLAMS networks are addressed in 40 CFR 58.25. Under Section 58.25, States/ Tribes are required to annually develop and implement schedules to modify the SLAMS network to eliminate any unnecessary stations or to correct any inade quacies indicated by the annual network review required by 58.20(d). As pa rt of the annual network review, evaluations of the special networks established as part nership agreements between EPA and GRIC DEQ should also be conducted. Modifi cations to these networks shoul d be recommended as a result of this annual review.

An important objective of the network modificat ion process is determining whether or not sufficient ambient air quality information and data are being provided by the regulatory and other special monitoring networks to satis fy the principal data needs. If sufficient air quality data are not being collected, the deficient area must be identified and co rrective action taken to resolve the problem. Conversely, if it is determined that excessive data are being collected (e.g., there are redundant sites resulting in data that agree closely), then efforts need to be taken to determine where dis-investment should be made and on what schedule.

Network modifications may be initiated by EPA or proposed by GRIC DEQ and agreed to by EPA. Network modifications may result from revisions to the Part 58 regulations, systems audits, site visits, or performance evaluations; special studies, population increases/decreases; air quality concentrations consistently recorded below the NAAQS; loss of permission to use a site; demolition of a building which is used for monitoring; building construction; growth of trees; changes in roadways; change in neighborhood type of use, etc.

3.3 Determining Conformance with Append ix D and Special Monitoring Requirements

With regard to Appendix D requirements, this network review is intended to determine the adequacy of the network in terms of number and lo cation of monitors. Specifically, (1) is GRIC DEQ meeting the number of monitors required by the Part 58 Appendix D design criteria requirements; (2) are the monitors properly located based on the monitoring objectives and spatial scales of representativeness presented in Appendix D. For special monitoring networks, conformance determinations will be conducte d in accordance with program documents applicable to the special networks.GRIC DEQ Page 6 10/17/2007

3.3.1 Number and Location of Monitors

For SLAMS, the number of monitors required and their location is not specified in the regulations but rather is dete rmined by EPA Region 9 and GRIC DEQ on a case-by-case basis to meet the monitoring objectives specified in A ppendix D. Adequacy of the network may be determined by using a variety of tools, including the following:

• analyses of historical monitoring data,

• maps of emissions densities,

• dispersion modeling,

• special studies/saturation sampling,

• best professional judgement,

• TIP requirements,

• revised monitoring strategies (e.g., new re gulations, reengineering air monitoring network),

• monitoring network maps and network desc riptions with site objectives defined.

Appropriate location of monitors can be determined on the basis of stated objectives. Maps, graphical overlays, and GIS-based information are extremely helpfu l in visualizing or assessing the adequacy of monitor locations. Plots of poten tial emissions and/or historical monitoring data versus monitor locations are especially useful. When questions arise ab out the adequacy of a particular location, modeling or spec ial studies may be appropriate.GRIC DEQ Page 7 10/17/2007

4.0 Network Evaluation and Recommendations/Proposed Modifications

4.1 Ozone (O 3 , 44201)

National Ambient Air Quality Standards (NAAQS):

• 8-hour average of the 4 th highest measured O 3 concentration averaged over three consecutive years, not to exceed 0.08 ppm at any given monitoring site.

GRIC’s Ozone monitoring network is comp rised of two sites communitywide.

4.1 Ozone (O3, 44201)

Parameter Instrument 1 Instrument 2 AQS # 700104021 700304013 Pollutant Type Ozone Ozone Date Established 7/1/2002 May 2003 Site ID/ Location Sacaton – GRIC DEQ Building St Johns – Gila Crossing North Middle School Sampler Make & Model API 400A API 400A Classification SLAMS SLAMS Scale Regional, rural Regional, rural Objective Population Population Intlet Height 5 meters 4 meters Distance from Tree Dripline NA NA Obstacle Description None None Height of Obstacle NA NA Distance and Direction NA NA Airflow Arch 360 degree 360 degree Furnace or Incinerator Flue None None Distance and Direction NA NA Distance between Collocated Samplers NA NA Nearest Road Pima Street Pecos Road Distance and Direction to Road 12 meters – East 12 meters – North Traffic Count (ADT) Not available Not available Schedule Continuous, Seasonal (Apr-Oct) Continuous, Seasonal (Apr-Oct) Surrounding Area Residential/ Bu siness Residential/ Business Site Groundcover Pavement Pavement/gravel rock Frequency of instrument check Biweekly Biweekly Last two audits June 2007 June 2007 Does Site Meet App D&E Criteria Yes Yes Action for 2006 Continue ContinueGRIC DEQ Page 8 10/17/2007

Ozone

Sacaton Site/ Sacaton, AZ AQS # 700104021 Address: 35 Pima Street, Sacaton, AZ

SLAMS site Ozone

Adequacy Sacaton Site is a regional scale State and Lo cal Air Monitoring Site for Ozone. It is located ~40 miles southeast of the metro Phoe nix. The Sacaton site contains ozone and meteorological monitors. Exceedences This site has not exceeded the one or eight hour standard. Justification for continued monitoring The Sacaton site is a long term trend site and operates on a seasonal schedule from April through October.

St Johns Site/ Laveen, AZ AQS # 700304013 Address: 4208 W. Pecos Road, Laveen, AZ 85339 SLAMS site for Ozone

Adequacy St Johns is a regional scale site for Ozone established in 2002. It is located ~25 miles southwest of Phoenix near South Mountain Park. Exceedences This site has not exceeded the one or eight hour standa rd in the past 3 years. Justification for continued monitoringGRIC DEQ Page 9 10/17/2007

The St Johns site is a long term trends s ite and operates on a seasonal schedule from April through October. It is located on the northwest end of the Community.

4.2 Particulate Matter (PM 10 , 81102)

National Ambient Air Quality Standard (NAAQS), 2002:

• Twenty-four hour average PM 10 concentration not to exceed 150 μg/m 3 on more than one occasion per year when averaged over three years.

GRIC’s Particulate Matter 10 monitoring netw ork consists of one site community-wide.

4.2 Particulate Matter 10 (PM10, 81102)

Parameter Instrument 1 Instrument 2 AQS # 700404021 poc 1 700404021 poc 2 Pollutant Type PM10 PM10 Date Established 1/1/2005 1/1/2005 Site ID Casa Blanca – Va Ki Elementary School Casa Blanca – Va Ki Elementary School Sampler Make & Model R&P FRM Partisol 2000 R&P FRM Partisol 2000 Classification SLAMS SLAMS Scale Neighborhood, regional Neighborhood, regional Objective Population Population Intlet Height 5 meters 5 meters Distance from Tree Dripline NA NA Obstacle Description None None Height of Obstacle NA NA Distance and Direction NA NA Airflow Arch 360 degree 360 degree Furnace or Incinerator Flue None None Distance and Direction NA NA Distance between Collocated Samplers NA NA Nearest Road Casa Blanca Road Casa Blanca Distance and Direction to Road 12 meters – East 12 meters – East Traffic Count (ADT) Not available Not available Schedule One in three day One in six day Surrounding Area Reside ntial/ Business/ Agriculture Residential/ Business/ Agriculture Site Groundcover Pavement Pavement Frequency of Flow rate veri fication Quarterly Quarterly Last two flow rate audits June 2007 June 2007 Does Site Meet App D&E Criteria Yes Yes Action for 2006 Continue ContinueGRIC DEQ Page 10 10/17/2007

Additional Monitors: Two GRIC DEQ recently deployed two R&P Continuous PM10 TEOM samplers at Casa Blanca Site and St Johns Site. DEQ is drafting Quality A ssurance Plan and conductin g quality control and quality control assessments on TEOM samplers. Workplan to implement in 2008.

Recommendations/Proposed Modifications: GRIC is anticipating expansion of Particulate Matter (PM10) FRMs operations with TEOM continuous samplers at this s ite and at St Johns. Operation of the entire PM10 network is under re view and recommendations will be made at a later date.

Casa Blanca Site/ Bapechule, AZ AQS # 700404021 Address: Casa Blanca/ Preschool Road, Bapchule, AZ 85221 SLAMS site for PM10

Adequacy Casa Blanca Site is a neighborhood scale site for PM10 established in 2002. It is located in a mixed agriculture/residential area in District 5. Exceedences This site has exceeded the daily for PM10 th ree times in 2006. Th e three exceedances have been reported and flagged due to natural events episodes. Justification for continued monitoring The Casa Blanca PM10 samplers are located in the Community’s central agricultural sources. Additional PM10 samplers will be deployed at Casa Blanca. Casa Blanca is also a trends monitoring site.

4.3 Other PM10 Monitoring

Note: The following sites have been recommended to USEPA Region 9 for inclusion into the PM10 network. This information is being provided in this assessment for comment by EPA Region 9.

Sacaton AQS # 700104021 Address: 35 Pima Street, Sacaton, AZ 85247 SLAMS site for PM10 Sampling frequency: ContinuousGRIC DEQ Page 11 10/17/2007

Explanation Sacaton is neighborhood scale residential site. The si te’s primary objective is to characterize air quality conditions impacting the town of Sacat on and the nearby residents. Special Purpose Monitoring (SPM) conducted since 2005 has docum ented numerous exceedances of the 24 hour NAAQS at Casa Blanca which is approximately 8 miles away. A viol ation of the current NAAQS appears likely.

The Agency intends to monitor with continuous devices (FEM).

Recommendation Given the likelihood of a NAAQS violation, add Sacaton to the GRIC / EPA Region 9 monitoring network.

St Johns AQS # 700304013 Address: 4208 W. Pecos Road, Laveen, AZ 85339 SLAMS site for PM10 Sampling frequency: Continuous

Explanation St Johns is an existing middle/neighborhood scale re sidential site. The resi dential site typifies many similar areas in the GRIC community. The site provides air quality information to a population of over 2,000 residents. The site plays an essential role in transport and development of neighboring jurisdictions. Exceedances of the current or proposed 24 hour NAAQS are not expected.

Recommendation Given the number of residents in the St Johns community served by this site, add St Johns into the GRIC/ EPA Region 9 network.GRIC DEQ Page 12 10/17/2007



### 5.0 References

1. Code of Federal Regulations, Title 40, Part 58, Appendix A, B, D, E, U.S. Government Printing Office, 2006.

2. Code of Federal Regulations, Title 40, Pa rt 50, U.S. Government Printing Office, 2006.

3. Code of Federal Regulations, Title 40, Pa rt 53, U.S. Government Printing Office, 2006.

4. Code of Federal Regulations, Title 40, Pa rt 58, U.S. Government Printing Office, 2006.

5. U.S. EPA, Revised Requirements for Desi gnation of Reference a nd Equivalent Methods for PM 2.5 and Ambient Air Quality Surveillance for Particulate Matter -Final Rule. 40 CFR Parts 53 and 58. Federal Re gister, 62(138):38763-38853. July 18, 1997.

6. Guidance for Network Design and Optimum Site Exposure for PM 2.5 and PM 10 , J.G. Watson, et. Al., U.S. EP A/OAQPS, December 15, 1997.

7. SLAMS/NAMS/PAMS Network Review Guidance, EPA-454/R-98-003, March 1998.

8. Guideline on Ozone Monitoring Site Selection, EPA-454/R-98-002, August 1998.GRIC DEQ Page 13 10/17/2007



### Appendix A

GRIC Ambient Air Monitoring DataGRIC DEQ Page 14 10/17/2007

Table A-1. Sacaton and St Johns Ozone Data (IN PPM), 1 Hour Averages

Table A-2. Sacaton and St Johns Ozone Data (IN PPM), 8 Hour Averages Year Maximum Reading 2 nd Highest Reading 3 rd Highest Reading 4 th Highest Reading Number of Daily Exceedances Expected Exceedance Rate Number of Sample Hours Sacaton 2004 0.093 7/13/04 0.077 4/24/04 0.075 5/12/04 0.075 5/14/04 0 0 5020 seasonal 2005 0.089 7/19/05 0.087 5/23/05 0.082 4/16/05 0.079 4/13/05 0 0 5087 seasonal 2006 0.085 8/9/06 0.084 7/1/06 0.084 7/26/06 0.079 6/30/06 0 0 4927 seasonal St Johns 2004 0.082 9/12/04 0.079 4/27/04 0.079 5/1/04 0.079 9/11/04 0 0 5050 seasonal 2005 0.093 7/19/05 0.086 4/16/05 0.086 5/18/05 0.086 6/23/05 0 0 5085 seasonal 2006 0.078 6/26/06 0.075 6/20/06 0.074 6/15/06 0.070 6/7/06 0 0 4694 seasonal

Year Maximum Reading 2 nd Highest Reading 3 rd Highest Reading 4 th Highest Reading 3 Year Avg of the 4 th Highest Number of Daily Exceedances Number of Sample Hours Sacaton 2004 0.076 7/13/04 0.072 4/24/04 0.071 5/14/04 0.071 5/15/04 NA 0 5020 seasonal 2005 0.080 7/19/05 0.076 4/16/05 0.073 7/20/05 0.072 4/15/05 NA 0 5087 seasonal 2006 0.074 7/1/06 0.072 4/18/06 0.072 8/9/06 0.070 6/18/06 0.07 0 4927 seasonal St Johns 2004 0.076 5/1/04 0.074 7/25/04 0.072 4/25/04 0.072 5/12/04 NA 0 5050 seasonal 2005 0.079 7/19/05 0.078 4/16/05 0.075 5/18/05 0.073 6/30/05 NA 0 5085 seasonal 2006 0.066 6/7/06 0.066 6/26/06 0.065 6/15/06 0.062 5/10/06 0.07 0 4694 seasonalGRIC DEQ Page 15 10/17/2007

TABLE A-3. Casa Blanca PM10 Data (IN ug/m3)

a - At least one data point during this year was flagged due to an exceptional event and excluded from calculation. Year Maximum Reading

(Date) 2nd Highest

(Date) 3rd Highest

(Date) 4th Highest

(Date) Number of Daily Exceedances Expected Exceedance Rate 3 Year Average of the Expected Exceedance Rate

2005 146 12/12/05 106 07/18/05 98 04/22/05 98 11/09/05 0 0 NA

2006 a 246 a 04/14/06 184 a 06/25/06 161 a 08/21/06 152 12/16/066 0 0 NA