Assessment of Qualification for Treatment Under the Arizona Natural and Exceptional Events Policy for the High Particulates (PM 10 ) Concentration Event in the Buckeye Area on September 18, 2004 Arizona Department of Environmental Quality Air Quality Division Air Assessment Section March 17, 2005 Contact: Shawn Kendall, Arizona DEQ (602) 771-2349, kendall.shawn@azdeq.us J:\AQD\ASSESS\SpecialProjects Unit\Episode Summaries\Buckeye 18 Sept 2004 PM Episode\FinalReportSept 18 2004.doc
Assessment of Qualification for Treatment Under the Arizona Natural and Exceptional Events Policy for the High Particulates (PM 10 ) Concentration Event in the Buckeye Area on September 18, 2004 Executive Summary Background Elevated concentrations of particulate matter 10 microns or smaller (PM 10 ) were measured at the Maricopa County Buckeye site on September 18, 2004. The elevated values were recorded with PM 10 samplers operated by the Maricopa County Environmental Services Department (MCESD) at Buckeye. The 24-hour average PM 10 concentrations recorded at this location was 288µg/m 3. The 24-hour standard is 150µg/m 3. The elevated values are related to windblown dust associated with intense regional thunderstorm activity. This document provides a comparison to qualifying conditions described in the Arizona Department of Environmental Quality (ADEQ) Technical Criteria Document for Determination of Natural Exceptional Events for Particulate Matter Equal to or Less than Ten Microns in Aerodynamic Diameter (PM 10 ) document dated May 31, 2000, referred to as the TCD in this document, and the Supplement for Regional Natural Exceptional Events document dated February 10, 2005, referred to as the TCD Supplement in this document. Summary of Assessment under the TCD The event was examined using the criteria defined in the TCD. It was found that the local wind speeds were not high enough to qualify as a natural exceptional event. Summary of Assessment under the TCD Supplement The event was examined using the procedures defined in the TCD Supplement. For the purpose of this document, a Regional Natural Exceptional Event is defined as an adverse air quality event over a broad geographic area resulting from natural sources or caused by meteorological conditions that overwhelm control strategies (including BACM) for anthropogenic sources. It was found that the high concentration event was caused by a large thunderstorm cell that formed in northern Mexico and traveled north through Arizona transporting particulates over a large geographic area. As a result, the event qualifies as a Regional Natural Exceptional Event and is appropriate for treatment under the Natural and Exceptional Events Policy. Conclusion The PM 10 event at the Buckeye monitor on September 18, 2004, should be remain flagged in EPA s AQS data base as being caused by high winds resulting from a Regional Natural Exceptional Event. 1
1. Background on September 18, 2004 Event Background ADEQ has developed and adopted an Air Quality Exceptional and Natural Events Policy 1, similar to the Environmental Protection Agency s (EPA) Natural Events Policy (NEP) 2. The policy describes the requirements and procedures that are to be followed in the event of an air quality exceptional and natural event in Arizona. ADEQ developed this policy to govern the responses by the State and local jurisdictions to the occurrences of air quality natural events in Arizona, pursuant to A.R.S. 49-424(3). When an Arizona natural event is observed and verified by ADEQ based on the analysis of meteorological and PM 10 monitoring data, the characteristics of the high wind event are to be defined by the state based on analysis of meteorological data parameters listed in the Arizona NEP and the unique conditions existing in Arizona, pursuant to ADEQ s Technical Criteria Document for Determination of Natural Exceptional Events in Arizona 3, and the recently adopted Supplement to the TCD to address Regional Natural Exceptional Events (RNEE) 4. Elevated emissions from natural and/or well-controlled human-caused sources resulting from high winds events are exempted from additional regulation, except for the procedural requirements of the EPA s NEP. The recently adopted Supplement to the TCD was established to recognize natural phenomenon that can contribute to elevated PM 10 concentrations that are not specifically driven by local source meteorological conditions, which was the basis of the May 2000 TCD. It identifies three general categories of natural events that can result in elevated PM 10 concentrations: Long-range transport of smoke from wildfires; Long-range transport of dust from soils, usually without high transport winds; and/or, Emissions resulting from violent storms that generate emissions over a broad geographic area. The Supplement requires an analysis under the May 2000 TCD be performed to determine if the event qualifies as a natural or exceptional event under the Policy. If it does not, the Supplement requires a further examination to be performed to determine if one of the above categories of natural sources contributed to the event. Under the ADEQ policy, when an exceedance of the PM 10 National Ambient Air Quality Standard (NAAQS) is observed, ADEQ may make a determination that the exceedance is the result of one of the types of events considered in the federal NEP as a natural event, based on technical and scientific evidence. ADEQ and/or the county air pollution control agencies will perform an initial standard data quality review to determine the veracity of the reading. 1 ADEQ, 0159.000 Air Quality Exceptional and Natural Events Policy, April 28, 1999. 2 EPA, Areas Affected by PM10 Natural Events, memorandum dated May 30, 1996. 3 ADEQ, Technical Criteria Document for Determination of Natural Exceptional Events for Particulate Matter Equal to or Less Than Ten Microns in Aerodynamic Diameter (PM10), May 31, 2000. 4 ADEQ, Technical Criteria Document for Determination of Natural Exceptional Events for Particulate Matter Equal to or Less Than Ten Microns in Aerodynamic Diameter (PM10) Supplement to Address Regional Exceptional Events, February 10, 2005. 2
Within six months after the date of the natural event, ADEQ and/or the county air pollution control agencies must prepare a finding that Arizona NEP may be applicable. If the exceedance is valid and related to a high wind event, ADEQ and/or the county air pollution control agencies will hold a public meeting in the community near the monitoring site where the exceedance occurred to educate interested members of the public, request additional technical data input, and begin the planning process. Within 18 months after the date of the air quality exceptional event, ADEQ and/or the county air pollution control departments, in conjunction with the local planning agencies certified pursuant to A.R.S. 49-406, and affected stakeholders shall prepare the draft Natural Events Action Plan (NEAP) for review by EPA. Monitoring Site and Data History The Buckeye site (AQS Code 04-013-4011) is located at 26453 W. MC-85 Buckeye, AZ. The site was established August 1, 2004. This site is a SLAMS location for Carbon Monoxide, Ozone, PM-10, and NO 2 operated by the Maricopa County Air Quality Department (MCAQD). The spatial scale of the PM 10 monitor is neighborhood, and the monitoring objective is high population exposure with high concentration. The PM 10 monitoring frequency was changed from 1 in six days to hourly as of October 1, 2004. On September 18, 2004, this monitoring site measured a 24-hour average PM 10 concentration of 289 micrograms per cubic meter that exceeded the 24-hour average NAAQS of 150 micrograms per cubic meter. 2002 2003 2004 Max. 8-hr CO Avg. (PPM) * * 0.5 Number exceedances 8-hr CO * * 0 Max. 1-hr O3 Avg. (PPM) * * 0.088 Number exceedances 1-hr O3 * * 0 Max. 8-hr O3 Avg. (PPM) * * 0.068 Number of Daily Exceedances >0.08 * * 0 Three year avg. of 4 th High * * # Max. 24-hr PM 10 Avg. (ug/m3) * * ** 289 Number exceedances 24-hr PM 10 * * 1 Annual PM 10 Avg. (ug/m3) * * # Annual NO2 Avg. (PPM) * * # * Not Operating **Indicates an Exceedance of the Standard. # Indicates <75% Data Recovery Data Quality Assurance MCAQD has certified each PM 10 concentration as valid and suitable for submittal to the EPA Air Quality System (AQS) database. Meteorology Summary Synoptic Weather Features: A 500mb long-wave trough axis extended from the Pacific Northwest to Southern California with steering flow aloft from the south and southwest. Tropical Storm Javier was located over the Pacific Ocean just west of the tip of Baja California Sur. Plentiful moisture was being shed from Javier and was moving north and northeast over Arizona. Southern Arizona weather conditions: At 2:00 p.m. a large complex of thunderstorms with its origin over Sonora moved north over Santa Cruz and Pima Counties. It then tracked north - northeast over Pinal, eastern Maricopa, and Gila Counties during the late 3
afternoon and evening hours. Outflow from the complex generated additional showers and thunderstorms as well as strong outflow winds. Local weather conditions: Rain showers were seen to the east of the Phoenix area by 6:00 a.m. and during the mid-morning hours outflow winds due to this activity reached the metro area and caused east to southeast winds between 10-20 mph. By 10:00 a.m. large convective clouds had developed to the south of the metro area and continued to build and then dissipate thru the early afternoon period with thunder being heard over south Phoenix between 1:00 and 2:00 p.m. At the same time, a cluster of large storms could be seen to the south of the metro area, and around 4:00 p.m. an outflow boundary from that activity reached the SE valley where Williams Gateway Airport reported a visibility of 2 miles in blowing dust along with southeast winds of 23 mph with gusts to 29 mph. During the next four hours strong gusty winds, blowing dust, moderate to heavy rain, and thunderstorms occurred over most of the valley. At 5:00 p.m. Sky Harbor Airport had 7 miles visibility in blowing dust and southeast winds that gusted to 36 mph. At the same time Luke AFB had 3/4 miles visibility in blowing dust; Scottsdale Airport had 4 miles visibility in blowing dust and southeast winds that gusted to 31 mph; Goodyear Airport had 5 miles visibility in blowing dust with southeast wind gusts to 34 mph; Glendale Airport had 2 miles visibility in blowing dust with easterly wind gusts to 33 mph; and Chandler Airport had blowing dust and southeast wind gusts to 33 mph. Similar conditions existed at 6:00 p.m. when Goodyear had 5 miles in blowing dust, Glendale and Deer Valley Airports 4 miles, Chandler 7 miles, and Luke AFB 1 mile visibility. The max wind gust recorded at that time was at Glendale with easterly gusts to 44 mph. At 7:00 p.m. all sites except Phoenix had east to southeast winds that ranged from 23-30 mph. By 8:00 p.m. the activity was on the decrease and by 9:00 p.m. had ended over most of the area. 4
2. Assessment Under the Technical Criteria Document The objective of this analysis is to see whether the wind speeds and aridity associated with a PM 10 exceedance are extreme enough to qualify the day as a natural exceptional event. This section is concerned only with the meteorological tests that are conducted to determine whether the exceedance date in question is considered meteorologically exceptional. These tests are described in the Arizona Department of Environmental Quality document Technical Criteria Document for Determination of Natural Exceptional Events for Particulate Matter Equal to or Less than Ten Microns in Aerodynamic Diameter (PM 10 ) dated May 31, 2000. Of the five meteorological tests, the first three concern wind speeds. The first test (Test #1), which is whether there were three or more hours with average wind speeds above the dust re-suspension threshold, must be passed for the day to qualify as exceptional. The next two tests (#2 and #3) concern the 24-hour average wind speed. If test number 2 is passed, then the day qualifies. If the day fails test #2, then test #3 is performed. Failing test number 3 eliminates the day as an exceptional event. Passing it then requires that test numbers 4 and/or 5, concerning aridity be performed. The following is the analysis performed on the September 18, 2004 event at the Buckeye monitoring site. The wind speed data used in this analysis was obtained from the Maricopa County Buckeye monitoring site and is summarized in Table 1 on the following page. Test #1: Did three or more hours during the exceedance have hourly average winds in excess of 7 mps (15.7 miles), per hour? The Buckeye wind system recorded only 2 hours above 7 meters per second (6:00 P.M. and 7:00 P.M.). The event fails this test. Test #2: Was the 24-hour average wind speed equal to or greater than the 99.9 th percentile level? The 99.9 th percentile trigger level for Phoenix area (as defined in the TCD) is 6.3 meters per second or 14.1 miles per hour. The observations at Buckeye show an average speed of 3.14 mps or 7.02 mph. The event fails this test. Test #3: Was the 24-hour average wind speed equal to or greater than the 97 th percentile level? The 97 th percentile trigger level for Phoenix area (as defined in the TCD) is 4.6 meters per second, or 10.3 miles per hour. The observations at Buckeye show an average speed of 3.14 mps or 7.02 mph. The event fails this test. 5
Table 1. Hourly averaged wind speeds at Maricopa County Buckeye Site September 18, 2004 (Speed in meter per second) Hour MC Buckeye Site Wind Speed 1 0.9 2 0.1 3 1.7 4 2.0 5 1.7 6 1.8 7 1.7 8 0.8 9 1.8 10 3.0 11 2.7 12 3.1 13 2.5 14 1.3 15 2.5 16 2.9 17 3.8 18 10.1 19 8.1 20 5.1 21 5.6 22 4.8 23 3.8 24 3.5 avg 3.14 99.9 th percentile 24-hour average 6.3 97 th percentile 24-hour average 4.6 Conclusion Based upon on-site wind data collected at the Buckeye site on September 18, 2004, the event fails the criteria for a natural exceptional event established in the May 31, 2000, Technical Criteria Document. Further analysis to determine if the event qualifies as a Regional Natural Exceptional Event under the February 10, 2005, Supplement to the Technical Criteria Document must be performed if the event is a RNEE to qualify for treatment under the Natural and Exceptional Events Policy. 6
3. Assessment Under the Supplement To Address Regional Natural Exceptional Events The previous section of this document contains the detailed air quality data discussion and other background related to the event, along with an analysis of the criteria contained in the May 2000 TCD. This section of this document examines the question of whether one of the RNEE categories of events contributed to the event. The previous analysis included a review of limited meteorological and air quality information related to the event. From this information, it appeared that air quality was impacted by a thunderstorm event that resulted from an influx of moisture into the area from a hurricane to the south of Arizona. Based on this preliminary observation, additional information was collected and analyzed to determine if the event should be considered a Regional Natural Exceptional Event. Supplemental Information Gathered for Analysis The GOES-West satellite images for 1:00 p.m. through 6:00 p.m. were cropped to show Arizona and the surrounding three states that make up the Four Corners area and the area off the coast of Mexico where Tropical Storm Javier was located. These were organized in a time sequence to correspond with the arrival time of storm activities in southern and central Arizona and shown in Figure 1. The thunderstorm cell formed southwest of the Tucson area in northern Mexico. The storm intensity was at its peak at approximately 3:00 p.m. and moved rapidly to the northward. ADEQ operates a series of visibility camera sites for urban haze in the Phoenix area. Cameras are located: west of Phoenix looking west toward the White Tank Mountains; west of Phoenix looking south toward the Estrella Mountains; in central Phoenix looking northeast toward Camelback Mountain; in central Phoenix looking south toward South Mountain; and, east of Phoenix looking east toward the Superstition Mountains. Images from these cameras were organized in a time series in Figure 2a (4-5pm) and 2b (5-6pm). For the purpose of comparison, images from 1:00 p.m. were included in the sequence to show how a relatively unobstructed view from the camera would appear. The dust storm arrived in the area west of Phoenix at approximately 4:15 p.m. The view of South Mountain shows the widespread nature of the wall of dust as it approached the Phoenix area. The intensity of the dust to the west of Phoenix and north of Buckeye is evidenced by the images from the White Tank camera. Data from the AZMET network operated by the University of Arizona was obtained and organized for analysis. It is summarized in Figure 3. Data from the stations are organized from left to right based on the arrival of strong south to southwest outflow winds from the thunderstorm. Based on the above referenced information it appears that the thunderstorm cell formed in northern Mexico and proceeded northward throughout the day. Highest winds from the event were in the areas southeast of Phoenix area earlier in the afternoon, and then tracked to the northwest with very high winds arriving in Buckeye between 5:00 and 6:00 p.m., and then in Aguila to the northwest of Buckeye about an hour later. Heaviest precipitation was observed at the Queen Creek monitor, followed later in the evening at 7
Aguila. These sites also had some of the highest wind gusts. Buckeye received the strong winds, but with much less precipitation. The visibility camera on images at the White Tanks clearly show a wall of dust hit the area (north and east of Buckeye) at approximately 4:30 p.m. as did the images of South Mountain. It appears the heaviest part of the dust storm moved from the East Valley to the west. Winds in the central Phoenix area were lower than the winds measured to the east or the west of Phoenix, probably due to shielding by the mountains and increased surface roughness associated with urban development. The actual track of the major part of the storm seemed to fan out after passing through Phoenix with very high winds being monitored at Aguila to the northwest and at Payson to the northeast. Conclusion Based on this analysis, the following conclusions can be drawn: The thunderstorm event was regional in nature. The surface (3-meter) wind data supports the conclusion drawn from the examination of the GEOS-West Satellite image data that the storm formed in northern Mexico and moved rapidly to the north affecting most of southern and central Arizona. The track of the storm seems to have favored higher winds to the west of Phoenix. This track is similar, but slightly to the west of the storm track from the major thunderstorm cell that affected air quality on August 13, 2004. Precipitation from the storm varied over the region, with heavy precipitation being observed at only a few locations, and usually after the wind event and flow reversal had occurred. It is, therefore, likely that large quantities of particulate matter were transported over very long distances by winds associated with the regional storm. The sources of particulates measured at monitoring stations throughout the Phoenix area cannot be determined accurately because of the large wall of dust that migrated and recharged itself as it transported from southern Arizona into central Arizona after being caused by the moisture from Tropical Storm Javier. The PM 10 concentration measured in Buckeye on September 18, 2004, was significantly affected by a Regional Natural Exceptional Event that has been flagged accordingly in EPA s AQS data base. 8
I R V I S Figure 1. GOES-West Infra-red (IR) and Visible (VIS) Satellite Images for September 18, 2004 (1pm-6pm) Showing Formation and Transport of Thunderstorm Cell from Southern Arizona. 1:00 P.M. 2:00 P.M. 3:00 P.M. 4:00 P.M. 5:00 P.M. 6:00 P.M. 9
East of Phoenix looking east Superstitions North of downtown Phoenix looking south South Mountain Downtown Phoenix looking northeast Camelback West of Phoenix looking to the south Estrella West of Phoenix looking to the west White Tank 1:00 pm No image available 4:00 pm 10 4:15 pm No image available 4:30 pm 4:45 pm Figure 2a. ADEQ Urban Visibility Camera Images from September 18, 2004 (4-5pm) No image available 5:00 pm
East of Phoenix looking east Superstitions North of downtown Phoenix looking south South Mountain Downtown Phoenix looking northeast Camelback West of Phoenix looking to the south Estrella West of Phoenix looking to the west White Tank 1:00 pm No image available 5:00 pm 11 No image available 5:15 pm 5:30 pm No image available 5:45 pm Figure 2b. ADEQ Urban Visibility Camera Images from September 18, 2004 (5-6pm) 6:00 pm
Figure 3. AZMET Data Showing Progression of Thunderstorm Cell on September 18, 2004 Eloy 4-5 pm 4-5 pm 5-6 pm Southern Pinal County Northern Pinal/Maricopa Phoenix Area 6-7 pm Buckeye Other Stations North of Buckeye Hr T(F) RH Rn Spd Max Dir Hr T(F) RH Rn Spd Max Dir Hr T(F) RH Rn Spd Max Dir Hr T(F) RH Rn Spd Max Dir Hr T(F) RH Rn Spd Max Dir 1 94 26 0 5 12 173 1 95 26 0 1 14 134 1 95 30 0 4 9 138 1 94 37 0 6 13 144 1 77 37 0 9 17 190 2 94 27 0 5 9 176 2 96 26 0 6 13 138 2 95 28 0 4 9 128 2 96 30 0 6 16 171 2 78 34 0 8 20 173 3 84 55 0 8 19 249 3 94 31 0 12 22 132 3 97 26 0 4 9 136 3 97 30 0 5 14 161 3 78 34 0 7 14 179 4 78 75 0 5 26 22 4 87 50 0.08 12 24 138 4 97 26 0 4 8 115 4 96 29 0 7 12 184 4 80 34 0 7 15 185 5 75 80 0 21 30 144 5 73 85 0.59 18 30 145 5 88 45 0.01 9 24 149 5 96 28 0 9 15 202 5 78 36 0 8 18 175 6 72 88 0 13 25 140 6 72 92 0.12 17 25 132 6 75 78 0.05 13 28 149 6 84 57 0 21 38 129 6 76 41 0 9 18 178 7 72 87 0 9 17 46 7 73 90 0.04 13 19 110 7 74 86 0.03 10 17 127 7 75 80 0.12 19 31 127 7 68 72 0 16 30 184 8 72 89 0 9 13 54 8 72 88 0 14 22 93 8 74 82 0 10 18 113 8 75 81 0.09 14 28 104 8 62 89 0 11 21 173 9 72 89 0.01 4 9 60 9 73 79 0 14 21 96 9 74 72 0 4 12 86 9 74 85 0 12 21 88 9 61 90 0 5 12 176 10 72 87 0 3 5 141 10 75 77 0 10 16 103 10 74 72 0 3 6 91 10 73 84 0 11 19 91 10 61 92 0 4 11 168 11 73 82 0 7 11 136 11 75 76 0 6 12 97 11 75 71 0 5 7 107 11 73 79 0 9 16 86 11 60 94 0.01 3 6 117 12 74 84 0 6 9 137 12 74 82 0 4 6 62 12 75 69 0 4 8 99 12 74 78 0 8 15 83 12 60 94 0 2 5 135 1 93 33 0 8 14 127 1 96 22 0 5 11 134 1 91 32 0 14 23 161 2 95 30 0 7 13 118 2 96 23 0 5 12 144 2 91 31 0 14 24 180 3 95 29 0 5 11 159 3 98 21 0 4 13 124 3 91 32 0 13 20 184 4 81 68 0.03 13 23 148 4 97 23 0 5 11 131 4 92 33 0 11 20 188 5 76 79 1.05 13 36 155 5 87 44 0 12 27 165 5 93 30 0 12 20 181 6 70 97 1.28 16 33 155 6 73 86 0.18 11 25 158 6 92 30 0 11 17 199 7 69 94 0.18 17 29 79 7 73 93 0.12 12 20 120 7 85 46 0 16 31 149 8 70 86 0.08 13 22 72 8 72 84 0 12 22 115 8 75 75 0.15 22 32 136 9 71 87 0 10 17 104 9 74 74 0 6 14 105 9 71 91 0.94 16 39 117 10 73 83 0 11 16 121 10 75 71 0 4 7 101 10 71 89 0 14 24 112 11 73 83 0 4 11 114 11 76 69 0.00 3 7 97 11 71 83 0 9 15 120 12 73 86 0 3 6 129 12 75 72 0 2 4 144 12 71 81 0 6 15 109 Maricopa Queen Creek PHX - Encanto Mesa Buckeye Payson Aguila AZMET Monitoring Locations Legend for Highlighting Winds Over 20 Mile per Hour Winds Over 30 Miles per Hour Explanation of Column Headings Hr Ending Time of Hour (1=Noon-1pm) T(F) Temperature (Degrees Farenheight) RH Relative Humidity (Percent) Rn Precipitation of Rain (Inches in Hour) Spd Avg. Wind Speed (Miles per Hour) Max Max. Wind Speed (Miles per Hour) Dir Wind Direction (from - Magnetic N) AZMET Network Description The Arizona Meteorological Network (AZMET) provides meteorological data and weatherbased information to agricultural and horticultural interests operating in southern and central Arizona. Meteorological data collected by AZMET include temperature (air and soil), humidity, solar radiation, wind (speed and direction), and precipitation. - Winds are at 3 meters above the ground - Direction is Magnetic (add 12 for True N) See web @ http://ag.arizona.edu/azmet/ Prepared by S. Kendall / ADEQ 3/17/05