capcog 2013 monitoring network assessment

1

CAPITAL AREA COUNCIL OF GOVERNMENTS OZONE MONITORING

NETWORK ASSESSMENT

FINAL REPORT, Task 4.2, Rider 8 Phase III Work Plan

Prepared by the Capital Area Council of Governments Air Quality Program

February 2013

Prepared in Cooperation with the Texas Commission on Environmental Quality

The preparation of this report was financed through grants from the State of

Texas through the Texas Commission on Environmental Quality

2

Executive Summary This report is an assessment of how the ozone monitoring network in the Capital Area Council of

Governments (CAPCOG) region meets various goals for an air quality monitoring network and a

blueprint for future ozone monitoring efforts within the region for 2013 and beyond. The assessment

includes the following elements:

1. a description of the goals and constraints for CAPCOG’s air monitoring program,

2. a history of the development of the ozone monitoring network in the CAPCOG region,

3. detailed monitoring and spatial analysis of the existing network,

4. analysis of the results of special monitoring projects undertaken by CAPCOG in 2011 and 2012,

5. a situational analysis of the adequacy of the network and individual sites to fulfill certain goals, and

6. recommendations for 2013 and future monitoring ozone monitoring network configurations.

The general geographic area covered by this analysis is the 10-County CAPCOG region, which consists of

the same counties as the Texas Commission on Environmental Quality (TCEQ) Region 11 office: Bastrop,

Blanco, Burnet, Caldwell, Fayette, Hays, Lee, Llano, Travis, and Williamson Counties. Within the CAPCOG

region, Bastrop, Burnet, Caldwell, Hays, Travis, and Williamson Counties are particularly important since

they would constitute the nonattainment area if one or both of the Texas Commission on Environmental

Quality’s (TCEQ)’s regulatory ozone monitors in Travis County violate the ozone National Ambient Air

Quality Standard (NAAQS). Therefore, most of the analysis in this report relates to these counties, which

make up the Austin-Marble Falls Consolidated Statistical Area (Austin CSA).

CAPCOG’s recommendations for the monitoring network fall along three lines:

Recommendations for configuration of ozone monitors for the 2013 ozone season,

Recommendations for changes in the configuration of ozone monitors given the same level of resources, and

Recommendations for changes in the configuration if the funding remains cut to the levels in the 2012/2013 appropriation from the Rider 8 grant.

For 2013, CAPCOG recommends that it continues to operate all six of its current air quality monitoring

stations and to establish temporary monitoring stations in southwestern Austin and in Lockhart.

CAPCOG also recommends reassessing the monitoring network once FY 2014 funding levels have been

established and the EPA has proposed a new ozone standard.

3

Table of Contents Executive Summary ................................................................................................................................. 2

Section 1: Goals and Constraints for Air Monitoring Program .................................................................. 7

Section 1.1: Air Monitoring Program Goals .......................................................................................... 7

Section 1.2: Resource Constraints ...................................................................................................... 10

Section 1.3: Other Constraints ........................................................................................................... 11

Section 2: Network History .................................................................................................................... 12

Section 3: Site-By-Site Network Analysis ................................................................................................ 14

3.1: Measured Concentrations ........................................................................................................... 14

3.1: Frequency of High Ozone Conditions........................................................................................... 15

3.3: Correlation Analysis .................................................................................................................... 18

3.4: Trend Impacts ............................................................................................................................. 19

3.5: Upwind and Downwind Positioning of Monitors ......................................................................... 20

3.7: Areas and Populations Served by Regional Monitors ................................................................... 22

Section 4: Bottom-Up Analysis ............................................................................................................... 28

4.1: Spatial Analysis of June 2006 Photochemical Modeling ............................................................... 28

4.2: Emissions Inventory Analysis ....................................................................................................... 40

4.3: Analysis of Mobile Surface Monitoring in 2011............................................................................ 42

4.4: Temporary Monitoring in 2012 ................................................................................................... 45

Liberty Hill Results ......................................................................................................................... 46

Elroy Results .................................................................................................................................. 46

4.5: Assessment of Monitoring Start and End Dates ........................................................................... 47

Section 6: Conclusions and Recommendations ...................................................................................... 48

Works Cited ........................................................................................................................................... 52

Appendix A: Selected Back-Trajectories for Liberty Hill and Elroy Temporary Monitoring Stations 2012 . 54

Appendix B: Complete 8-Hour Ozone Averages for Temporary Sites ...................................................... 85

Appendix C: June 2006 Photochemical Modeling Episode Plots and Data .............................................. 90

Figure 1: Region 11 Ozone Monitors 1973 - 2012................................................................................... 14

Figure 2: Average Annual Number of High Ozone Days 2010 – 2012 (During CAPCOG Ozone Monitoring Only) ..................................................................................................................................................... 16

Figure 3: # Days Measuring Maximum 8-Hour Ozone >60 ppb for Region During CAPCOG Monitoring... 17

Figure 4: Resultant Wind Direction from 6:00 – 18:00 CST at CAMS 3 on Days >= 60 ppb 2001-2009 ..... 22

4

Figure 5: Square Miles of CAPCOG Region Served by TCEQ and CAPCOG Monitors (TCEQ = red and blue, CAPCOG = green) ................................................................................................................................... 23

Figure 6: CAPCOG Region Population Served by TCEQ and CAPCOG Monitors (TCEQ = red and blue, CAPCOG = green) ................................................................................................................................... 26

Figure 7: Area and Population Served by Each Ozone Monitor in the CAPCOG Region ........................... 27

Figure 8: Daily Maximum 8-Hour Ozone Concentrations, June 3, 2006................................................... 29

Figure 9: Maximum 8-Hour Ozone Concentrations, June 13, 2006 ......................................................... 30

Figure 10: Modeled and Monitored 8-Hour Ozone Concentrations at Selected Monitoring Sites, June 3 and June 13, 2006 ................................................................................................................................. 31

Figure 11: Daily Maximum 8-Hour Ozone, June 29, 2006 ....................................................................... 32

Figure 12: Daily Maximum 8-Hour Ozone, June 14, 2006 ....................................................................... 33

Figure 13: Austin CSA 4th Highest Daily 8-Hour Ozone Concentrations, June 2006 Episode .................... 35

Figure 14: Number of Days in Austin CSA with 8-Hour Ozone Averages Above 75 ppb During June 2006 Ozone Episode....................................................................................................................................... 36

Figure 15: Number of Days with 8-Hour Ozone Averages Over 70 ppb for June 2006 Ozone Episode ..... 37

Figure 16: Estimated 4th Highest 8-Hour Ozone Concentration in Selected Cities in Burnet and Caldwell Counties ................................................................................................................................................ 38

Figure 18: Examples of Surface Mobile Monitoring Data Collected in 2011 ............................................ 42

Figure 19: Mobile Monitoring Data Compared to Max One-Hour Ozone Concentrations, August 29, 2011.............................................................................................................................................................. 44

Figure 20: 2012 Ozone Monitoring Locations ......................................................................................... 45

Figure 17: Seasonal Distribution of High Ozone Days 2010 - 2012 .......................................................... 47

Figure 24: Liberty Hill Back-Trajectory for June 1, 2012 .......................................................................... 55

Figure 25: Liberty Hill Back-Trajectory for June 9, 2012 .......................................................................... 56

Figure 26: Liberty Hill Back-Trajectory for June 23, 2012 ........................................................................ 57





Figure 31: Liberty Hill Back-Trajectories for August 7, 2012 .................................................................... 62

Figure 32: Liberty Hill Back-Trajectories for August 8, 2012 .................................................................... 63

Figure 33: Liberty Hill Back-Trajectories for August 10, 2012 .................................................................. 64




5



Figure 39: Liberty Hill Back-Trajectory for August 29, 2012 .................................................................... 70



Figure 42: Liberty Hill Back-Trajectories for September 10, 2012 ........................................................... 73

Figure 43: Liberty Hill Back-Trajectory for September 11, 2012 .............................................................. 74



Figure 46: Liberty Hill Back-Trajectories for October 3, 2012 .................................................................. 77

Figure 47: Elroy Back-Trajectories for August 11, 2012 .......................................................................... 78



Figure 50: Elroy Back-Trajectories for September 10, 2012 .................................................................... 81



Figure 53: Elroy Back-Trajectories for October 3, 2012........................................................................... 84

Table 1: Estimated Operating Costs of Air Quality Monitoring Network for 2013 Ozone Season............. 10

Table 2: Monitoring Equipment available for 2013 Monitoring Network Operations .............................. 11

Table 3: TCEQ Region 11 Ozone Monitoring Network Milestones .......................................................... 12

Table 4: 2012 Design Values for Ozone Monitors in TCEQ Region 11 ...................................................... 15

Table 5: Average # Days Per Year Recording the Maximum 8-Hour Average for the Region on Days > 60 ppb, 2010 - 2012 ................................................................................................................................... 17

Table 6: Correlation for All Matched Days When One or Both Sites Had 8-Hour Ozone > 60 ppb, 1997 - 2012 ...................................................................................................................................................... 18

Table 7: # of Years with Correlation > 0.75 for All Matched Days When One or Both Sites Had 8-Hour Ozone > 60 ppb ..................................................................................................................................... 18

Table 8: Number of Ozone Seasons in Operation for Region 11 Monitoring Stations .............................. 19

Table 9: Position of CAPCOG Monitors Relative to TCEQ Regulatory Monitors ....................................... 20

Table 10: Resultant Wind Direction from 6:00 - 18:00 CST at CAMS 3 and 38 on Days >= 75 ppb 2006 - 2011 ...................................................................................................................................................... 21

Table 11: Square Miles of Austin CSA Served by TCEQ and CAPCOG Monitors ....................................... 23

Table 12: Summary of Rankings of CAPCOG Monitors by Area Served.................................................... 24

6

Table 13: Austin CSA Population Served by Regional Ozone Monitors .................................................... 24

Table 14: Austin MSA Population Proximity to Nearest Ozone Monitor ................................................. 25

Table 15: Summary of Rankings of CAPCOG Monitors by Population Served .......................................... 26

Table 16: Distances Between Monitoring Stations in Miles .................................................................... 34

Table 17: Modeled Daily Average NOX Concentrations, June 28, 2006 ................................................... 39

Table 18: Estimated NOX Emissions in 2006 and 2012 in the Austin MSA (tons per day) ......................... 40

Table 19: Wells Permitted and Completed in the Eagle Ford Shale Play ................................................. 41

Table 20: Comparison of Liberty Hill Monitoring Data to Nearby Stations, May 29 - November 1 ........... 46

Table 20: Comparison of Liberty Hill Monitoring Data to Nearby Stations, May 29 - November 1 ........... 46

Table 21: Earliest and Latest Calendar Dates with High-Ozone Days Measured ...................................... 47

Table 22: Dates when Temporary Monitors Measured Maximum 8-Hour Ozone Averages Over 60 ppb 54

Table 23: Maximum Daily 8-Hour Ozone Averages at Liberty Hill and Elroy Stations, 2012 ..................... 85

7

Section 1: Goals and Constraints for Air Monitoring Program

Section 1.1: Air Monitoring Program Goals EPA’s network assessment guidance provides a list of typical goals for an air quality monitoring network.

Not all of the goals mentioned by EPA are applicable to ozone; for instance, speciation is relevant for

particulate matter monitoring but not ozone monitoring. The following list represents the goals that are

applicable to ozone monitoring.

Compliance with NAAQS,

Air quality model evaluation,

Trend tracking,

Monitor the area of maximum precursor emissions,

Monitor the area of maximum pollutant concentration,

Monitor background concentrations,

Monitor surrogate pollutants,

Transport/border characterization,

Interpolation and understanding pollutant gradients,

Accountability/performance measurement,

Forecasting assistance,

Public reporting of the air quality index.

The TCEQ’s two ozone monitoring stations in the region – CAMS 3 and CAMS 38 – are the only two

monitors in the region used for regulatory purposes to assess the region’s compliance with the ozone

NAAQS. CAPCOG’s ozone monitors undergo different calibration procedures and do not undergo a

formal validation process like TCEQ’s monitoring data do. Therefore, it is not appropriate to use these

monitors to the region’s compliance with the ozone NAAQS.

CAPCOG is currently using a June 2006 photochemical modeling episode to conduct ozone modeling in

the region, and four CAPCOG monitors were in operation during all or a portion of this episode. The

previous ozone episode CAPCOG has used was a September 1999 episode; due to the scarcity of

monitoring data during this period, it required a significant amount of resources to get the model to

work properly. Model validation has been one of the driving factors behind the deployment of research

monitors in the region, and proper siting of monitors is important for model validation.

Trend tracking is another important function of several of CAPCOG’s air quality monitors. CAMS 601 and

614 have been in operation for ten or more years and their continued operation would enable

continued tracking of ozone trends in the region. CAMS 684, 690, and 1675 (although it was moved to

another part of San Marcos) have been in operation since 2006 – 2008, providing less of a long-term

trend, but showing trends consistent with what is shown at CAMS 601 and 614 nevertheless. CAMS 6602

is the only monitoring station that doesn’t provide a significant historical record for at this point. To the

extent that trend tracking is a goal of monitoring, it would tend to discourage any movement of existing

monitoring stations in order to continue tracking trends over time. One important trend over the past

few years that the current monitoring network may not be adequately tracking is the increase in ozone

8

precursor emissions from oil and gas drilling and production to the south of the Austin area in the Eagle

Ford Shale.

Since VOC and NOX are precursors to ozone, monitoring these pollutants as part of a regional ozone

monitoring network can provide data useful for understanding regional ozone formation. To this extent,

it would be important to position these monitors in locations with high expected VOC or NOX emissions.

TCEQ’s decision to move the regulatory NOX monitor that had been at CAMS 38 to CAMS 3 was in part

prompted by a request from CAPCOG to reposition it to measure expected high NOX emissions in the

more urban setting of CAMS 3. CAMS 6602 is currently positioned to detect any NOX plumes from power

plants to the east and northeast that might contribute to regional ozone formation.

While the purpose of regulatory monitors is in part to determine whether the maximum ozone

concentrations in an area are violating the NAAQS, fewer monitors may be required for a region than

would be needed to measure the maximum ozone concentration in certain situations. In the Austin

area, where high ozone levels typically occur at the regulatory monitors when winds come out of the

southeast or northeast, TCEQ’s two regulatory monitors may not be ideally positioned to measure the

region’s highest ozone levels on certain types of days. CAMS 614, CAMS 1675, and CAMS 690 are all

positioned in part to measure the maximum ozone concentrations in the region under certain

meteorological conditions.

One of the most important roles CAPCOG’s air quality monitoring network plays is in providing data on

the background ozone concentrations in the region. Background ozone levels make up about 80% of

high ozone, and upwind monitors can help document the background concentration and calculate the

local contribution. Since TCEQ does not operate any air quality monitors upwind of the region, it would

not be possible to assess background and local contributions with only monitoring data. CAPCOG’s

CAMS 601, 684, and 6602 are all positioned in large part to provide a decent picture of ozone levels

entering the region in order to understand these local and background contributions.

While the region does not have nearly as dense of a monitoring network as other parts of the state,

there are enough monitors to provide some degree of interpolation and understanding of pollution

gradients. Additional monitors in key positions with relatively little monitoring coverage currently would

improve the ability to conduct such analysis.

So some extent, ozone monitoring can be used to measure and track the success of ozone control

strategies, although given the significant amount of local NOX reductions required to produce changes in

ozone levels (about 15-20 tons per day of NOX reduction per ppb of ozone reduction, based on

photochemical modeling conducted by U.T.) and the regional nature of ozone formation, ozone

monitoring won’t be a particularly precise tool to evaluate particular control strategies other than the

overall expected reductions throughout the inventory within the region.

EPA’s guidance indicates that for ozone forecasting, upwind NOX measurements can be helpful. To this

extent, CAPCOG’s CAMS 6602 can be useful for ozone forecasting, and additional NOX monitoring to the

south or southeast could also be helpful in forecasting ozone levels.

Finally, monitoring is also useful public information that citizens can use to limit their exposure to air

pollution, health professionals can use to plan for increases in respiratory-related problems, and

9

members of the community can use to take action to reduce their emissions. Having a local air quality

monitor can also increase awareness of air quality issues – to the extent that a community must rely on

a monitor 20 miles away or more for a representation of their local air quality conditions, that

community may not have enough information to take preventative measures.

In order to perform this monitoring network assessment, CAPCOG relied on EPA’s guidance to states for

conducting five-year monitoring network assessments (U.S. Environmental Protectino Agency, February

2007). According to this guidance, network assessment includes:

7. Re-evaluation of the objectives and budget for air monitoring,

8. Evaluation of a network’s effectiveness and efficiency relative to its objectives and costs, and

9. Development of recommendations for network reconfigurations and improvements.

EPA advises that “networks should be designed to address multiple, interrelated air quality issues and to

better operate in conjunction with other types of air quality assessments (e.g., photochemical modeling,

emission inventory assessments). In light of this guidance, CAPCOG has identified the following goals for

its monitoring program:

1. Measure background ozone concentrations,

2. Measure maximum ozone concentrations,

3. Provide air quality data specific to communities outside of the Austin urban core,

4. Track historical trends, and

5. Conduct air quality model evaluations.

CAPCOG’s Air Quality Program is chiefly interested in providing air monitoring data that is useful to the

local communities in the region and secondarily interested in providing air monitoring data that would

be useful to regulatory agencies such as TCEQ and EPA. CAPCOG’s Air Quality Program believes that

measuring background ozone concentrations is critical for this region because of the extent to which

background levels contribute to local ozone levels. And while CAPCOG’s Air Quality Program is not in a

position to conduct regulatory monitoring, TCEQ has indicated that it does not plan to install any

additional ozone monitors in the region beyond the two it currently operates, and since these are not

sufficient to characterize maximum ozone concentrations on many days, additional monitoring is

needed to develop a more comprehensive understanding of ozone formation within the region and to

help ensure that the region actually does attain and maintain the ozone NAAQS. While TCEQ’s

regulatory monitors may be well-positioned to measure ozone levels in large parts of Austin, there is

enough regional variation in ozone levels on any given day that they have limited use for characterizing

ozone levels in other parts of the region. Maintaining a broad ozone monitoring network enables

citizens of the CAPCOG region to have more relevant data on air quality conditions within their own

communities. Finally, in the event that counties in the CAPCOG region are designated nonattainment,

continued monitoring will be important to ensure that any ozone reductions strategies are accurately

modeled so as to avoid unnecessary regulation and provide useful and accurate information to local

decision-makers about the effectiveness of emission reduction strategies.

10

Section 1.2: Resource Constraints The total cost of operating the existing six monitoring stations in 2013 would likely cost approximately

$60,000, including about $42,000 in contractor operating costs, $10,000 in utility costs, $5,000 for a

collateral LEADS license, and $3,000 in equipment repair or replacement costs. Each additional monitor

would add approximately $7,250 to the total cost of operating the monitoring network. CAPCOG has an

estimated $98,825.82 ($71,049.78 from TCEQ, $15,000 from Travis County, and $12,776.04 from the

City of Austin) available for all remaining contractual work and utilities for 2013. Some of these funds

are currently designated for photochemical modeling work as part of CAPCOG’s Phase III Work Plan

under its Rider 8 Near-Nonattainment Grant. This money could be repurposed for monitoring through a

work plan amendment with TCEQ, if deemed a priority and TCEQ technical staff is in agreement with

additional monitoring tasks. The funding from Travis County can only be used for operating CAMS 601

and 684 unless the contract is amended.

CAPCOG has estimated that the total cost of operating the six permanent air quality monitors in 2013

would be $52,000 without considering equipment repair costs (approximately $3,500 - $4,000 in 2012)

and assuming the same level of service for the same duration (April 15 – October 31). Dios Dado

Environmental, Ltd. (Dios Dado) – CAPCOG’s air quality monitoring contractor – provided cost estimates

for operating each of CAPCOG’s air quality monitors and the cost of writing a final report as part of its

proposal services for the 2012 ozone season (Dios Dado, February 2012). The 2012 figures were

increased by 5% to reflect Dios Dado’s proposal that expenses for 2013 be increased by that amount if

the contract is renewed. CAPCOG also provided the monthly operating costs in order to assess the cost

of expanding the coverage. These costs reflect operation from April 15 – October 31, but there have

been days in March and November when the region’s regulatory ozone monitors have measured 8-hour

ozone concentrations over 60 ppb. The grand total includes the cost of a final report.

Table 1: Estimated Contractor Operating Costs of Air Quality Monitoring Network for 2013 Ozone Season

Station Total Cost Monthly Operating Cost

CAMS 601 $8,519.70 $1,068.65

CAMS 614 $6,878.28 $843.12

CAMS 684 $6,855.14 $863.95

CAMS 690 $6,039.84 $751.70

CAMS 1675 $7,251.63 $917.06

CAMS 6602 $6,139.56 $740.43

TOTAL $42,093.64 $5,184.92

The marginal operating cost for the ozone monitoring equipment at the Fayette monitoring station may

be reduced to a total of $5,166.40 for the season, and $570 per month if TCEQ also contracts with

CAPCOG to perform PM2.5 monitoring at that location over the same period. These costs do not include

utility costs at these sites (phone, electricity), which currently costs about $10,000 annually. These

expenditures are funded through the Rider 8 Work Plan, Task 5.2: Administrative Support.

The following table shows the number of operating pieces of equipment owned by CAPCOG or TCEQ and

used at the six CAMS during the 2012 ozone season. CAPCOG assumes that TCEQ will allow all of the

11

equipment it owns that it has allowed CAPCOG to use at these locations in 2012 will continue to be

made available for CAPCOG air quality monitors for the 2013 ozone season. Not included on this list are

pieces of equipment owned by CAPCOG that would need further repair.

Table 2: Monitoring Equipment available for 2013 Monitoring Network Operations

Equipment Type Description/Model Number CAPCOG TCEQ

Ozone Analyzer Tanabyte 722 4 0

Ozone Analyzer Dasibi 1008-AH 3 2

Nitrogen Oxides Analyzer API 200A 1 0

Wind Direction/Wind Speed Sensor R.M. Young Model 05305 5 0

Wind Direction/Wind Speed/Ambient Temperature Senor

F-460 0 3

Meteorological Tower N/A 1

Data Logger Zeno 3 3

Trailer N/A 2 2

Calibrator Tanabyte Model 322 1 0

Zero Air Generator Teledyne API Model 701 1 0

Pumps Thomas Pump Model 607CA316 2 0

Stainless Steel Compressed Gas Regulator

Scott-Marrin Model 2SS75-660-D4T

1 0

There are a total of 8 ozone analyzers, 1 nitrogen oxides monitor, 1 set of automated calibration

equipment, 8 meteorological sensors, and 6 data loggers available for 2013 monitoring operations. Dios

Dado allowed CAPCOG to use two Zeno data loggers for the short-term monitoring operation

undertaken in 2012, which may or may not be available for use in 2013. Of the four trailers available for

use in monitoring operations, three of them are deployed at existing continuous monitoring stations

(CAMS 601 and 614 for TCEQ-owned trailers and 690 for a CAPCOG trailer), with one in reserve available

for deployment to another site. CAPCOG has invested over $50,000 in upgrading its equipment during

the 2011 and 2012 ozone season, although the Dasibi 1008-AH ozone analyzers are quite old and could

need repair or replacement sometime in the next few years. Having operating ozone analyzers in

reserve would help avoid repair costs in 2012.

Under CAPCOG’s Phase III work plan, CAPCOG committed to operate at least five sites and report the

data to the LEADS program in 2013. Based on these costs, CAPCOG estimates that it should be able to all

of its current six sites, and up to two more monitoring stations.

Section 1.3: Other Constraints There are also political constraints in deploying a monitoring network – namely, CAPCOG will not deploy

a monitoring station in a jurisdiction that does not want to host the station. In 2011, CAPCOG presented

a proposal to the Burnet County Commissioners’ Court requesting approval to conduct temporary ozone

monitoring in the county. County Officials conveyed that they did not support the location of an ozone

monitor in their county, even for a temporary research purpose. Therefore, CAPCOG has no plans to

deploy a stationary monitor there at this point.

12

Section 2: Network History CAPCOG has been conducting ozone monitoring in the region since 2002. CAPCOG’s monitoring network

has grown from just one monitoring station in 2003 to six stations in 2012. CAPCOG’s network currently

includes including CAMS 6011 (Fayette County), CAMS 684 (McKinney Roughs), CAMS 690 (Lake

Georgetown), CAMS 1675 (San Marcos), and CAMS 6602 (Hutto). These monitors have played an

important role in helping characterize ozone within the region and serve to supplement the two ozone

monitors operated by TCEQ in Travis County – CAMS 3 (Murchison Middle School) and CAMS 38 (Austin

Audubon Society). Regional ozone monitoring efforts in the region began in January 1973 following the

passage of the Federal Clean Air Act. The table below provides a detailed timeline of ozone monitoring

milestones in the region.

Table 3: TCEQ Region 11 Ozone Monitoring Network Milestones

Date Milestone

January 1, 1967 TCEQ commences operation of monitoring station at East 53rd Street. Site

collects ozone data only in 1973.

January 1, 1973 TCEQ commences operation of monitoring station at Hunters Glen. Site

collects ozone data only in 1973.

January 1, 1974

TCEQ commences operation of monitoring stations at Lavaca & 17th Streets and TACB headquarters. Lavaca Street site collects ozone data only from the 4th quarter of 1976 through the 4th quarter of 1979. TACB headquarters site collects ozone data only from the 1st quarter of 1974 through the 3rd quarter

of 1979.

January 1, 1979

TCEQ commences operation of CAMS 3 at Murchison Middle School and an analytical lab site. CAMS 3 has been collecting ozone data since the first

quarter of 1979, while the analytical lab site collected data only in the first two quarters of 1980.

January 1, 1981 TCEQ commences operation of CAMS 25 at Parmer Lane and Mopac. Site

collects ozone data from the 3rd quarter of 1981 to the 1st quarter of 1997.

February 28, 1997 TCEQ commences operation of CAMS 38 at the Austin Audubon Society

located at 12200 Lime Creek Road in northwest Austin. TCEQ also shuts down CAMS 25 at Parmer Lane.

August 12, 1998 TCEQ commences operation of CAMS 62 at the San Marcos Airport located at

2041 Airport Drive in San Marcos.

May 18, 2000 LCRA commences operation of CAMS 601 located at 636 Roznov Road in

Round Top. The site has measured ozone, NOX, SO2, PM2.5, outdoor temperature, wind speed, and wind direction.

1 Note: CAMS 601 is still listed on TCEQ’s website as being owned by LCRA, but CAPCOG took over direct operation of the site from LCRA on September 1, 2012, through a site lease agreement. Prior to that date, CAPCOG was indirectly supporting the site through a contract with LCRA to operate an ozone analyzer there during ozone season.

13

Date Milestone

December 10, 2002 TCEQ commences operation of CAMS 613 at the Pflugerville Wastewater

Facility at 2609 East Pecan Street. Site measures ozone, NOX, SO2, temperature, wind speed, and wind direction.

March 11, 2003

CAPCOG commences operation of CAMS 614 at the Dripping Springs Elementary School at 29400 Ranch Road 12 in Dripping Springs. The measures NOX analyzer and wind speed/wind direction/outdoor temperature sensor in

a trailer.

April 5, 2003 TCEQ permanently ceases operation of CAMS 62 at the San Marcos Airport.

June 2, 2006

CAPCOG commences operation of CAMS 674 at 212 Commerce Street in Round Rock and CAMS 675 at 222 Sessoms Drive in San Marcos. Both sites

are equipped with an ozone analyzer and wind speed/wind direction sensors. The San Marcos site is located in a trailer.

August 16, 2006

CAPCOG commences operation of CAMS 684 at the McKinney Roughs Nature Park at 1884 State Highway 71 in Cedar Creek. The site is located in the

Visitor’s Center and is equipped with an ozone analyzer and wind speed/wind direction sensor.

November 3, 2006 TCEQ permanently ceases operation of CAMS 613 in Pflugerville.

September 20, 2007 CAPCOG commences operation of CAMS 690 at Lake Georgetown, 500 Lake

Overlook Drive in Georgetown. Site measures ozone, NOX, SO2, and wind speed/wind direction/outdoor temperature sensor in a trailer.

October 31, 2010 CAPCOG permanently ceases operation of CAMS 674 in Round Rock. CAPCOG ceases operation of NOX and SO2 monitoring at CAMS 601 and CAMS 690 due

to resource constraints.

May 18, 2011 CAPCOG commences operation of CAMS 6602 at 200 College Street in Hutto.

Site measures ozone, NOX, and SO2, and includes an automated calibrator, and wind direction/wind speed sensor.

September 14, 2011 CAPCOG permanently ceases operation of CAMS 675.

September 20, 2011 CAPCOG commences operation of CAMS 1675 at 599 Staples Road in San Marcos. Site includes an ozone analyzer and wind direction/wind speed sensor and is located inside a building at a water utility pump station.

May 29, 2012 CAPCOG commences operation of a temporary monitoring site at the Liberty Hill Fire Department. This site was equipped with an ozone monitor and wind

speed/wind direction sensor.

June 27, 2012 CAPCOG commences operation of a temporary monitoring site at the Elroy

Public Library. This site was equipped with an ozone monitor and wind speed/wind direction sensor.

November 2, 2012 CAPCOG ceases operation of temporary monitoring sites at Liberty Hill and

Elroy.

14

As the table above shows, the ozone monitoring network has grown considerably over time, especially

in the past ten years due to Rider 8 near-nonattainment program funding. The figure below shows the

number of ozone monitors in the region by year dating back to 1973.

Figure 1: Region 11 Ozone Monitors 1973 - 2012

In addition to monitoring ozone, TCEQ and CAPCOG have also conducted continuous monitoring of

nitrogen oxides (NOX) and volatile organic compounds (VOC), which are ozone precursors, and sulfur

dioxide (SO2), which can be an indicator of industrial pollution plumes. Currently, there are continuous

nitrogen oxides monitors at CAMS 3 (April 1, 2012 – present) and CAMS 6602 (2011 - present) and a

continuous sulfur dioxide monitor at CAMS 3. VOCs are monitored through non-continuous sampling at

CAMS 171. NOX monitoring has previously been conducted at CAMS 38 (1997 – 2012), CAMS 601 (2001

– 2010), CAMS 613 (December 2002 – January 2003), CAMS 614 (2003 – 2011), and CAMS 690 (2008 –

2010), and sulfur dioxide monitoring has previously been conducted at CAMS 601 and CAMS 690 (2008 –

2010).

Section 3: Site-By-Site Network Analysis This section provides a number of analyses to evaluate the degree to which each existing monitoring

station in the region advances various air monitoring goals, including measuring the maximum

concentrations of ozone, measuring trends in ozone over time, characterizing ozone transport into and

within the region, and providing specific data on pollution levels to different communities in the region.

3.1: Measured Concentrations EPA recommends comparing each monitor based the calculated design value of each site. The table

below represents the calculated design values of the two TCEQ ozone monitors and six CAPCOG

0

2

4

6

8

10

12

14

Regulatory Research

15

monitors reporting to the LEADS system in 2012. The design value calculations for the San Marcos

monitor include the values from CAMS 675 and 1675 since the monitor was moved a relatively short

distance (1.9 miles) within San Marcos in late 2011. The calculated design value for Hutto includes only

the 2011 and 2012 monitoring data; CAPCOG judged the Round Rock monitor that was decommissioned

at the end of 2010 was too far away (8.6 miles) to aggregate with the Hutto site for this analysis. If the

Round Rock data had been included in the calculation, the value would be 71 ppb, rather than 72 ppb.

Table 4: 2012 Design Values for Ozone Monitors in TCEQ Region 11

CAMS Design Value Rank

3 74 1

614 74 1

38 73 3

1675 72 4

6602 72 4

690 70 6

684 69 7

601 69 7

This comparison helps point to the increasingly important role CAMS 614 has played in the region’s

ozone monitoring network in recent years. While ozone levels at CAMS 3 have seemingly stalled at

about the 74-76 ppb range since 2007, the ozone design value for all of the other monitoring stations

have increased in recent years.

3.1: Frequency of High Ozone Conditions Another way to evaluate the importance of each monitoring station is to compare how many days each

monitoring station measured high 8-hour ozone averages. The chart below shows the average number

of days each monitoring station measured high 8-hour ozone averages above 60 ppb, 65 ppb, 70 ppb,

and 75 ppb from 2010 – 2012 during the periods when CAPCOG operated ozone monitors (May –

October 2010, April – October 2011, April – October 2012).

16

Figure 2: Average Annual Number of High Ozone Days 2010 – 2012 (During CAPCOG Ozone Monitoring Only)

These data again underline the importance of CAMS 614 to measuring high ozone in the region. It has

the 2nd most days above the 60 ppb, 65 ppb, and 70 ppb thresholds, and the most days above the 75

ppb threshold during the last 3 years. It also highlights the importance of CAMS 684 in characterizing

upwind air quality – it has fewer high ozone days than any other monitor at every level.

Another way to analyze these data is to compare the number of days each monitor measured the

region’s highest 8-hour ozone average on high ozone days. For this analysis, high ozone days were

defined as a day when any monitor in the region measured an 8-hour ozone concentration over 60 ppb.

CAPCOG limited the time periods for analysis to those when CAPCOG monitors were operating, since

TCEQ monitors have measured 8-hour ozone averages over 60 ppb outside of CAPCOG’s monitoring

periods. The figure below shows the number of days each monitor recorded the region’s highest 8-hour

ozone average during such days in 2010, 2011, and 2012.

0

5

10

15

20

25

30

35

>60 ppb >65 ppb >70 ppb >75 ppb

CAMS 3

CAMS 38

CAMS 601

CAMS 614

CAMS 684

CAMS 690

CAMS 675/1675

CAMS 6602

17

Figure 3: # Days Measuring Maximum 8-Hour Ozone >60 ppb for Region During CAPCOG Monitoring

This comparison provides some interesting insights into the monitoring network. Between 2010 and

2012, CAMS 614, 690, and 675/1675 have measured the region’s highest 8-hour ozone average more

frequently than CAMS 38. CAMS 601 and 684 rarely have had the region’s highest 8-hour average on

>60 ppb days, although 2011 seems to have been a bit of an anomaly in that CAMS 601 recorded 9 of

the region’s maximum 8-hour averages on >60 ppb days. The fairly consistent number of days when

CAMS 614 has recorded the region’s highest 8-hour average on such days likely reflects its role as a

downwind monitor on days when winds come out of the northeast. Perhaps the most surprising trend

over the past three years has been the increasing importance of monitoring in San Marcos. In 2012, it

recorded more of the region’s 8-hour ozone maxima on >60 ppb days than any other monitor. The table

below summarizes the 3-year totals for the data presented in the chart above.

Table 5: Average # Days Per Year Recording the Maximum 8-Hour Average for the Region on Days > 60 ppb, 2010 - 2012

CAMS # Days Rank

3 9.67 1

675/1675 8.33 2

614 8.00 3

690 6.33 4

38 4.00 5

6602 3.50 7

601 3.33 6

684 1.00 8

11

0 1

7

1 0

5

15

1

9 10

1

9 8

7

3

11

0

7

1

10

12

0 0

2

4

6

8

10

12

14

16

2010

2011

2012

18

3.3: Correlation Analysis EPA recommends that a network analysis includes an analysis of the correlation of monitoring values

between sites to determine if any of the sites are duplicative of data collected at another site. The less

two sites are correlated, the more the monitors are providing unique information relative to one

another. EPA specifically suggests that any pair of monitors with concentrations that correlate with a

coefficient over 0.75 may be duplicative. CAPCOG performed an analysis for all of the permanent

monitors stationed in Region 11 to assess whether any of the monitors were duplicative when 8-hour

ozone concentrations were over 60 ppb. The values represent the correlation between two sites’

maximum 8-hour ozone concentration on all days for which one or both sites had at least one 8-hour

ozone concentration above 60 ppb (provided the other site had at least one 8-hour ozone average on

the same day).

Table 6: Correlation for All Matched Days When One or Both Sites Had 8-Hour Ozone > 60 ppb, 1997 - 2012

CAMS 3 CAMS 38 CAMS 601

CAMS 614

CAMS 684

CAMS 690

CAMS 1675

CAMS 6602

CAMS 3 1 0.64 0.31 0.50 0.53 0.45 0.41 0.62

CAMS 38 0.64 1 0.33 0.47 0.33 0.58 0.33 0.47

CAMS 601 0.31 0.33 1 0.20 0.26 0.06 0.33 0.36

CAMS 614 0.50 0.47 0.20 1 0.24 0.31 0.54 0.58

CAMS 684 0.53 0.33 0.26 0.24 1 0.58 0.63 0.37

CAMS 690 0.45 0.58 0.06 0.31 0.58 1 0.22 0.54

CAMS 1675 0.41 0.33 0.33 0.54 0.63 0.22 1 0.28

CAMS 6602 0.62 0.47 0.36 0.58 0.37 0.54 0.28 1

As the table shows, there were no monitor pairings that had a correlation of over 0.75, although for

specific years, there have been a number of instances when pairs of monitors had correlations of over

0.75. In particular, the fact that the area’s two regulatory monitors have had correlations of over 0.75

for 8 of the 16 years they have been both been operating may suggest some duplication.

Table 7: # of Years with Correlation > 0.75 for All Matched Days When One or Both Sites Had 8-Hour Ozone > 60 ppb

CAMS 3 CAMS 38 CAMS 601

CAMS 614

CAMS 684

CAMS 690

CAMS 1675

CAMS 6602

CAMS 3 N/A 8/16 0/13 0/10 0/7 0/5 1/2 1/2

CAMS 38 8/16 N/A 0/13 2/10 0/7 1/5 0/2 0/2

CAMS 601 0/13 0/13 N/A 0/10 1/7 0/5 0/2 0/2

CAMS 614 0/10 2/10 0/10 N/A 0/7 0/5 1/2 1/2

CAMS 684 0/7 0/7 1/7 0/7 N/A 1/5 0/2 0/2

CAMS 690 0/5 1/5 0/5 0/5 1/5 N/A 0/2 0/2

CAMS 1675 1/2 0/2 0/2 1/2 0/2 0/2 N/A 1/2

CAMS 6602 1/2 0/2 0/2 1/2 0/2 0/2 1/2 N/A

It turns out that in all three of the years that have been used for photochemical modeling in Austin

(1999, 2002, and 2006), the correlation between these two sites was over 0.75. There was a high degree

19

of correlation among many of the monitors in the 2011 ozone season, which was one of the worst in

recent years. In 2011, the following pairings had correlations of over 0.75:

CAMS 3: CAMS 38, CAMS 1675, and CAMS 6602;

CAMS 38: CAMS 3, CAMS 614, and CAMS 690;

CAMS 614: CAMS 38, CAMS 1675, CAMS 6602;

CAMS 684: CAMS 690;

CAMS 690: CAMS 38 and CAMS 684;

CAMS 1675: CAMS 3, CAMS 614, and CAMS 6602; and

CAMS 6602: CAMS 3, CAMS 614, and CAMS 1675.

In 2012, on the other hand, no two monitoring stations had a correlation of over 0.75. One major

difference between the two years was that whereas in 2011, the worst ozone occurred in the later part

of the ozone season (August – September), which is often characterized by winds out of the east to

northeast, whereas in 2012, many of the highest ozone days were earlier in the ozone season when

winds more often come out of the south to southeast with lower background ozone levels.

As expected, the monitor with the least correlation to the other sites is CAMS 601. As a rural monitor

which would not be influenced by the Austin MSA’s emissions, it provides a rather unique picture of

ozone within the region. The monitors in the region with the highest correlation are TCEQ’s two

regulatory monitors (r = 0.64). CAPCOG’s CAMS 684 has a similar correlation to CAMS 1675 (0.63), and

CAPCOG’s CAMS 6602 has a similar correlation to CAMS 3 (0.62). Both CAMS 1675 and 6602 have only

recently been installed, so these figures may not represent a longer-term relationship between these

monitors.

There is a case to be made based on this analysis for moving CAMS 38 since it has had correlations with

CAMS 3 of over 0.75 in half of the years since it began operation.

3.4: Trend Impacts EPA recommends ranking each monitoring station by the length of time the monitoring station has been

in service. The longer a monitor has been in service, the more its data can provide a picture of air quality

trends. The table below ranks each of the monitoring stations by its time in service. Since the San

Marcos monitor was moved a relatively short distance (< 2 miles), it’s “trend” period is considered to

start with the installation of CAMS 675 in San Marcos on June 2, 6006.

Table 8: Number of Ozone Seasons in Operation for Region 11 Monitoring Stations

Station Installation Date Ozone Seasons Rank

CAMS 3 January 1, 1979 34 1

CAMS 38 February 28, 1997 16 2

CAMS 601 May 18, 2000 13 3

CAMS 614 March 11, 2003 10 4

CAMS 675/1675 June 2, 2006/September 20, 2011 7 5

CAMS 684 August 16, 2006 6 6

CAMS 690 September 20, 2007 5 7

CAMS 6602 May 18, 2011 2 8

20

3.5: Upwind and Downwind Positioning of Monitors One of the most important roles of CAPCOG’s monitors is to provide data on ozone concentrations

upwind and downwind of TCEQ’s regulatory monitors. To this end, CAMS 601 and 6602 are positioned

primarily to provide data on upwind ozone concentrations when winds are coming out of the southeast,

while CAMS 6602 is positioned to provide data on upwind ozone concentrations when winds are coming

out of the northeast. CAMS 614 serves primarily as a downwind monitor for the metro area when winds

come out of the northeast. CAMS 690 and CAMS 1675 can serve as upwind or downwind sites

depending on which way the wind is blowing. The following table provides the direction and distance of

each of CAPCOG’s six monitors from CAMS 3 and CAMS 38:

Table 9: Position of CAPCOG Monitors Relative to TCEQ Regulatory Monitors

Monitoring Site From CAMS 3 From CAMS 38

CAMS 601 66 miles east-southeast 76 miles east-southeast

CAMS 614 22 miles west-southwest 22 miles southwest

CAMS 684 23 miles southeast 34 miles southeast

CAMS 690 22 miles north 15 miles north-northeast

CAMS 1675 35 miles south-southwest 43 miles south

CAMS 6602 18 miles northeast 20 miles east-northeast

The position of these monitors can be compared to data compiled by the University of Texas at Austin

(UT) for CAPCOG’s ozone conceptual models for 2010 (The University of Texas at Austin, July 2010) and

2012 (The University of Texas at Austin, 2012) to see whether CAPCOG’s monitors are properly

positioned for measuring ozone levels upwind or downwind of the metropolitan area. The figure below

shows the wind direction from 6:00 – 18:00 CST on days when the Murchison or Audubon monitor

measured 8-hour ozone concentrations of 75 ppb or higher from 2006 - 2011.

21

Table 10: Resultant Wind Direction from 6:00 - 18:00 CST at CAMS 3 and 38 on Days >= 75 ppb 2006 - 2011

These data suggest that there may be some gaps in the region’s monitoring network for measuring

upwind and downwind ozone concentrations for days at or above the current standard of 75 ppb. CAMS

38 is 11 miles northwest of CAMS 3, enabling it to pick up ozone measurements downwind of CAMS 38

when winds come out of the southeast, but not when come out of the south-southeast, the most

common wind direction on such days. CAPCOG’s CAMS 690 cannot pick up downwind ozone

concentrations on such days either. CAMS 684 provides a direct representation of upwind ozone

concentrations on days when winds come out of the southeast, but not the more frequent south-

southeast. CAMS 614 is positioned west-southwest of CAMS 3, so it cannot provide the most direct

measurement of downwind ozone concentrations on days when winds come out of the north-northeast.

It may, however, be positioned far enough west of the urban areas of Travis County to detect downwind

ozone concentrations when winds are coming out of the east, and during those days, the plume from

the Decker Power plant would float over downtown Austin before arriving at the Dripping Springs

monitor. CAMS 6602 cannot provide a direct picture of upwind ozone concentrations on high ozone

days when the winds blow out of the north-northwest. CAMS 1675 is positioned south-southwest of

CAMS 38, which presumably enables it to detect high ozone days when winds are out of the north-

northeast. This may help explain why this monitor’s ozone values have been especially high in recent

years.

The relative importance of different wind directions changes when lower ozone thresholds are used in

this analysis. The figure below show the resultant wind direction from 6:00 – 18:00 Central Standard

Time (CST) on days when the Murchison monitor measured 8-hour ozone concentrations of 60-64 ppb,

65-69 ppb, and 70+ ppb at CAMS 3 from 2001 – 2009.

0

1

2

3

4

5

6

7

8N

NNE

NE

ENE

E

ESE

SE

SSE

S

SSW

SW

WSW

W

WNW

NW

NNW

CAMS 3

CAMS 38

22

Figure 4: Resultant Wind Direction from 6:00 – 18:00 CST at CAMS 3 on Days >= 60 ppb 2001-2009

These data support a more general conclusion that the south – to southeast direction is the most

important upwind region on high ozone days and the north-northeast to east-northeast direction is the

second most important upwind region for ozone. These data seem to indicate that at a threshold of 70

ppb and higher, the southeast direction is more important than the south-southeast direction and that

the northeast direction is more important than the north-northeast direction. However, for lower

thresholds, the most important upwind directions are, in order, south-southeast, southeast, and either

the northeast or the south depending on which threshold was used. The data also seem to indicate that

the lower the threshold, the more important the southern direction becomes.

The following table ranks the importance of each of CAPCOG’s monitoring stations as an upwind and

downwind monitor, based on the number of days it did measure or could have ozone upwind or

downwind of CAMS 3 on days >=70 ppb from 2001 - 2009.

Station Upwind Rank (days) Downwind Rank (days)

CAMS 601 3 (14) 5 (2)

CAMS 614 6 (2) 3 (16)

CAMS 684 1 (30) 4 (3)

CAMS 690 5 (4) 1 (18)

CAMS 1675 4 (6) 2 (17)

CAMS 6602 2 (18) 6 (0)

3.7: Areas and Populations Served by Regional Monitors Two of EPA’s recommended analyses involve the creation of the Thiessen polygon technique, whereby

each polygon consists of points closer to one particular site than any other site. These polygons can then

0

10

20

30

40

50

60

70

80N

NNE

NE

ENE

E

ESE

SE

SSE

S

SSW

SW

WSW

W

WNW

NW

NNW

70+ ppb

65+ ppb

60+ ppb

23

be used to analyze the land area and population “served” by each monitor, although this technique does

not take account of meteorology, topography, or proximity to emissions sources, so as EPA says, “some

areas assigned to a particular monitor may actually be better represented by a different monitor.”

In terms of area served, CAMS 684 serves the largest geographic area within the Austin CSA of any of

CAPCOG’s monitors at 1,238 square miles. CAMS 6602 covers the next largest area at 677 square miles,

with CAMS 614, 690, and 1675 serving somewhat smaller areas. The Fayette County monitor serves only

39 square miles in the Austin CSA. There are some small portions of southern Hays and Caldwell

Counties and northern Williamson County that are closer to monitors outside of a CAPCOG or TCEQ

Region 11 monitor. The one locality where this is particularly true is Luling, which is a Clean Air Coalition

member. Luling is closer to the Seguin monitor operated by TCEQ than it is to any CAPCOG monitor.

Table 11: Square Miles of Austin CSA Served by TCEQ and CAPCOG Monitors

Monitor Name Bastrop Burnet Caldwell Hays Travis Williamson Subtotal

CAMS 3 0 0 0 1 375 15 391

CAMS 38 0 502 0 0 236 113 851

CAMS 601 39 0 0 0 0 0 39

CAMS 614 0 118 0 377 137 0 632

CAMS 684 846 0 240 0 152 0 1,238

CAMS 690 0 178 0 0 0 450 628

CAMS 1675 0 0 247 296 6 0 549

CAMS 6602 11 0 0 0 118 548 677

CAMS 1047 0 222 0 0 0 9 231

CAMS 504 0 0 0 4 0 0 4

CAMS 506 0 0 59 0 0 0 59

TOTAL 896 1,019 546 679 1,025 1,135 5,300

If the entire CAPCOG region is considered instead of just the CSA, the relative importance of the

monitors changes significantly, as the chart below shows.

Figure 5: Square Miles of CAPCOG Region Served by TCEQ and CAPCOG Monitors (TCEQ = red and blue, CAPCOG = green)

0

500

1,000

1,500

2,000

2,500

CAMS 3 CAMS38

CAMS601

CAMS614

CAMS684

CAMS690

CAMS1675

CAMS6602

CAMS1047

CAMS504

CAMS506

24

These two geographies provide different rankings for the area served. The table below summarizes

these rankings.

Table 12: Summary of Rankings of CAPCOG Monitors by Area Served

Monitor Austin CSA Rank CAPCOG Rank

CAMS 601 6 3

CAMS 614 3 1

CAMS 684 1 2

CAMS 690 4 5

CAMS 1675 5 6

CAMS 6602 2 4

One notable feature of the coverage map is the fragmented coverage of Burnet and Caldwell County

due to their distances from the nearest ozone monitors. The table below shows the distances of the

communities in each county to the nearest CAPCOG ozone monitors.

Community County Closest CAPCOG Monitor Distance

Bertram Burnet CAMS690 20

Burnet Burnet CAMS38 28.45

Cottonwood Shores Burnet CAMS38 27.39

Granite Shoals Burnet CAMS38 31.2

Highland Haven Burnet CAMS38 32.38

Marble Falls Burnet CAMS38 24.77

Meadowlakes Burnet CAMS38 25.88

Lockhart Caldwell CAMS1675 16

Luling Caldwell CAMS1675 21.04

Martindale Caldwell CAMS1675 5.41

To the extent that either of these communities might be at risk for inclusion in an Austin CSA

nonattainment area, the lack of monitoring data in these counties prevent them from being able to use

monitoring data to differentiate air quality in their counties from the regulatory monitors in Travis

County, and locating monitors in these counties would provide more balanced spatial coverage for the

monitoring network.

In order to analyze the population served by each monitor, CAPCOG used the Thiessen polygons and an

overlay of 2010 population data from the U.S. Census Bureau. (U.S. Census Bureau, 2012). The table

below shows the populations served in the Austin CSA by each monitor.

Table 13: Austin CSA Population Served by Regional Ozone Monitors

Monitor Bastrop Burnet Caldwell Hays Travis Williamson Subtotal

CAMS 3 0 0 0 203 832,101 39,023 871,327

CAMS 38 0 25,564 0 0 88,757 152,050 266,371

CAMS 601 1,364 0 0 0 0 0 1,364

CAMS 614 0 18,783 0 43,672 45,450 0 107,905

25

Monitor Bastrop Burnet Caldwell Hays Travis Williamson Subtotal

CAMS 684 75,510 0 9,805 0 43,920 0 129,235

CAMS 690 0 3,229 0 0 0 125,689 128,918

CAMS 1675 0 0 27,438 121,573 1,333 0 150,344

CAMS 6602 2,090 0 0 0 76,818 141,166 220,074

CAMS 1047 0 1,887 0 0 0 696 2,583

CAMS 504 0 0 0 251 0 0 251

CAMS 506 0 0 6,707 0 0 0 6,707

TOTAL 78,964 49,463 43,950 165,699 1,088,379 458,624 1,885,079

Since the vast majority of the population in the region is concentrated close to the Austin urban core,

changing the region of analysis from the Austin CSA to the CAPCOG region does not change the

importance of each monitor much.

Another quantitative way to evaluate the monitoring network’s adequacy in serving the local population

is to calculate distances from population centers to the nearest monitor. The following table represents

the number of people living within 5 miles, 5-10 miles, 10-15 miles, and greater than 15 miles of the

nearest monitor within the 5-county Austin-Round Rock-San Marcos Metropolitan Statistical Area

(Austin MSA)2. Population data reflect the 2010 Census.

Table 14: Austin MSA Population Proximity to Nearest Ozone Monitor

Distance Population %

<5 Miles 509,629 29%

5-10 Miles 778,477 44%

10-15 Miles 355,692 20%

>15 Miles 144,294 8%

2 Bastrop, Caldwell, Hays, Travis, and Williamson Counties. Burnet County has only recently become a part of what would be the default nonattainment area if the region is ever designated nonattainment for ozone.

26

Figure 6: CAPCOG Region Population Served by TCEQ and CAPCOG Monitors (TCEQ = red and blue, CAPCOG = green)

Again, the two geographies provide somewhat different rankings, although the main difference is the

increased importance of CAMS 614 when the geography analyzed is the entire COG rather than just the

Austin CSA.

Table 15: Summary of Rankings of CAPCOG Monitors by Population Served

Monitor Austin CSA Rank CAPCOG Rank

CAMS 601 6 6

CAMS 614 5 3

CAMS 684 3 4

CAMS 690 4 5

CAMS 1675 2 2

CAMS 6602 1 1

One thing that both of these analyses show is that two of the counties in the Austin CSA are being

underserved by the current monitoring network – Burnet County and Caldwell County. All of the cities

and Census-designated places in Burnet County are at least 20 miles away from the nearest CAPCOG or

TCEQ Region 11 monitoring station. Lockhart is 16 miles away from the closest monitoring station, while

Luling is 18 miles away from the closest monitoring station (CAMS 506 in Seguin) and over 20 miles away

from the closest CAPCOG monitoring station. Establishing a CAMS in the vicinity of Lockhart should

provide a significantly more accurate picture of air quality in Caldwell County than the current network

would provide. Similarly, establishing a monitoring station in Marble Falls or Burnet would provide a

good representation of ozone exposure in Burnet County.

0

100,000

200,000

300,000

400,000

500,000

600,000

700,000

800,000

900,000

1,000,000

CAMS 3 CAMS38

CAMS601

CAMS614

CAMS684

CAMS690

CAMS1675

CAMS6602

CAMS1047

CAMS504

CAMS506

27

Figure 7: Area and Population Served by Each Ozone Monitor in the CAPCOG Region

28

Section 4: Bottom-Up Analysis This section provides analysis of the suitability of the monitoring network to meet CAPCOG’s goals using

a variety of tools, including analysis of special monitoring projects undertaken by CAPCOG in 2011 and

2012, emissions inventory analysis, and photochemical modeling from the June 2006 ozone episode.

This analysis also involves an evaluation of the appropriate beginning and end dates for seasonal ozone

monitoring in the region.

4.1: Spatial Analysis of June 2006 Photochemical Modeling The modeling results for the June 2006 photochemical modeling episode developed by TCEQ can be

spatially analyzed to evaluate the suitability of the current monitoring network to meet CAPCOG’s

monitoring goals. CAPCOG’s analysis of the results provided several key insights:

There is a need for monitoring in southwest Austin and western Travis County in order to measure the maximum eight-hour ozone concentrations for the region,

The current monitoring configuration otherwise does a reasonably good job of capturing upwind and downwind ozone concentrations if the standard remains at 75 ppb, but may need reconfiguration if the standard is lowered,

Burnet County’s modeled ozone levels are similar to those of Bastrop and Caldwell Counties and would likely show violation of any ozone standard set lower than 70 ppb,

On certain days, the ozone in the eastern part of the region is influenced by Houston ozone plume, but it may not reach all the way to CAMS 3 and 38,

The Sandow facility appears to have a significant impact on ozone levels in eastern Williamson County, CAMS 3 is a decent location for a NOX monitor, but maximum concentrations for the region would likely be measured to the south-southeast along the I-35 corridor near downtown Austin,

There may be some utility in continuous monitoring of NOX in the vicinity of Luling, due to expansion of NOx emission sources involved in shale oil and gas activity.

CAPCOG contracted with the University of Texas to perform various photochemical modeling tasks with

the June 2006 ozone episode in 2012, and for this project, CAPCOG requested that UT prepare graphical

displays of the maximum 8-hour ozone concentrations and average daily NOX concentrations for each 4

km x 4 km grid cell covering the Austin CSA, along with the underlying data. UT plotted the location of all

of the ozone monitors in operation in 2012 within the CSA on each tile plot for comparison.

CAPCOG first conducted a simple visual review of the tile plots to assess whether the data for any

episode days indicated any significant gaps in the monitoring network measuring the maximum 8-hour

ozone concentration. The clearest indication of the gap in monitoring to the southwest of the urban

core is evident in the plots for June 3, 2006, and June 13, 2006, when significant ozone plumes

originating near downtown Austin and traveling to the southwest would not have been detected in any

significant way by either CAMS 614 or CAMS 1675. The plots for these days are displayed below.

29

Figure 8: Daily Maximum 8-Hour Ozone Concentrations, June 3, 2006

30

Figure 9: Maximum 8-Hour Ozone Concentrations, June 13, 2006

CAPCOG analyzed the ozone modeling data and available monitoring data for these days to determine

the extent to which the monitors missed these plumes. The differences between the modeled maximum

8-hour ozone concentrations in these plumes and the grid cells containing CAMS 3, 614, and 1675 are

significant.

31

Figure 10: Modeled and Monitored 8-Hour Ozone Concentrations at Selected Monitoring Sites, June 3 and June 13, 2006

Date June 3, 2006 June 13, 2006

Max. 8-Hour Ozone Avg. Modeled 91.15 ppb 103.42 ppb

Max. 8-Hour Avg. Modeled at CAMS 3 75.87 92.38



Max. 8-Hour Avg. Monitored at CAMS 3 80 82

Max. 8-Hour Avg. Monitored at CAMS 614 71 71

The magnitude of the differences between these peak ozone concentrations, as modeled for the June

2006 episode and the concentrations where these monitors are currently located are clearly enough to

make a big difference in characterizing ozone levels within the region – 10-15 ppb. The distance

between CAMS 1675 and CAMS 614 simply provides too large of a gap to the city’s southwest to

properly measure downwind ozone concentrations on days when winds are coming out of the

northeast. Based on the region’s conceptual model, this occurs frequently enough during ozone season

that monitoring ozone levels there may provide the clearest picture if the area is in compliance with the

ozone NAAQS.

On days when winds were coming out of the southeast, another picture emerged. In several cases, the

tile plots showed areas of Lake Travis to the west of the Austin urban core having the region’s highest 8-

hour ozone concentrations, such as on June 29, 2006. On this day, while the tile plot does not extend

further to the east, it is apparent that the Houston ozone plume is causing very high ozone levels

throughout Fayette County and into eastern Bastrop County. Similarly, on June 14, 2006, when winds

appeared to be coming from the east, the Houston plume stretched across Fayette County into

Gonzales, Caldwell, and Bastrop Counties, while the Austin plume stretched westward into Blanco

County. The June 14, 2006 tile plot presented below also shows the significant impact of the

Alcoa/Sandow plant in Williamson County. On this particular day, CAMS 6602 in Hutto would have been

perfectly positioned to measure the plume.

32

Figure 11: Daily Maximum 8-Hour Ozone, June 29, 2006

33

Figure 12: Daily Maximum 8-Hour Ozone, June 14, 2006

Using the size of the ozone plume on June 13 – which is the most visually distinct urban plume available

from UT’s plots – the plume is approximately 20 miles wide and over 30 miles long – it is possible to

quickly identify where gaps exist in the network. Where two monitors are 17 or miles apart, there is a

risk that neither monitor would be able to detect an Austin urban ozone plume. The areas that appear

to run this risk are between CAMS 38 and CAMS 614, CAMS 614 and CAMS 1675; between CAMS 1675

and CAMS 684, and between CAMS 6602.

34

Table 16: Distances Between Monitoring Stations in Miles

3 38 601 614 684 690 1675 6602

3 0 11 66 22 23 21 35 18

38 11 0 76 22 34 14 42 20

601 66 76 0 81 44 76 71 63

614 22 22 81 0 37 37 25 39

684 23 34 44 37 0 39 34 28

690 21 14 76 37 39 0 56 14

1675 35 42 71 25 34 56 0 53

6602 18 20 63 39 28 14 53 0

The gaps in downwind measurements between CAMS 38 and CAMS 614 to the west of the urban core

and between CAMS 614 and CAMS 1675 to the southwest of the urban core indicate that there may be

a need for additional monitors – rather than simply moving existing monitors. The gaps between CAMS

1675 and CAMS 684 to the south-southeast and between CAMS 684 and CAMs 6602 to the northeast

make the risk of missing high background ozone levels on certain days. The ozone plume generated from

the Alcoa/Sandow facility is most clear on the plot for June 14, 2006 – it shows a narrower plume about

7 – 10 miles wide. Given the frequency with which high ozone days in the Austin area involve winds out

of the northeast, it may be worth either moving CAMS 6602 more to the southeast of its current

position or establish a new upwind monitor about ½ way between CAMS 6602 and CAMs 684.

In order to provide a clearer picture of the ozone levels across the Austin CSA during the June 2006

ozone episode, CAPCOG created three additional maps using the modeling data – one showing the

fourth highest daily eight-hour ozone concentration throughout the region, one showing how many

times a grid cell’s daily eight-hour average exceeded 75 ppb, and how many times a grid cell’s daily

eight-hour average exceeded 70 ppb. These maps are presented below.

35

Figure 13: Austin CSA 4th Highest Daily 8-Hour Ozone Concentrations, June 2006 Episode

36

Figure 14: Number of Days in Austin CSA with 8-Hour Ozone Averages Above 75 ppb During June 2006 Ozone Episode

37

Figure 15: Number of Days with 8-Hour Ozone Averages Over 70 ppb for June 2006 Ozone Episode

38

These maps further support the need for monitoring in southwestern Austin and in the Lake Travis area,

especially if the standard remains at 75 ppb. The high ozone in the Lake Travis area could be of

particular concern in terms of exposure since people often spend hours at a time outdoors on the lake

during the summer. Aside from these areas, though, it seems that at 75 ppb, the current monitoring

configuration within the Austin CSA would do a decent job characterizing upwind and downwind ozone

concentrations. If the standard is lowered to 70 ppb, however, it appears that there may be a need to

reposition monitors to better capture both upwind and downwind concentrations since the geographic

extent of the frequency surfaces appear to reach further outside of the urban area than the current

monitoring network would reflect. At 70 ppb, for instance, it might make sense to set up a downwind

monitor in Liberty Hill and another one in Wimberley, and it would make sense to set up upwind

monitors in the vicinity of Manor and southern Lockhart. These still may be useful places to monitor at

75 ppb, but moving any existing monitor to those locations may not provide incrementally more

information.

These maps and the underlying data also point out that there may be some utility in establishing

monitors in Caldwell County and Burnet County if the standard winds up getting set at 70 ppb. The

following table shows the 4th highest 8-hour ozone concentration for grid cells covering the communities

of Lockhart and Luling in Caldwell County, and Burnet and Marble Falls in Burnet County, along with an

estimated 8-hour average for 2012 if the levels in those areas have decreased in the same proportions

that CAMs 3’s 4th highest average has decreased since 2006 (from 82 ppb in 2006 to 74 ppb in 2012).

Figure 16: Estimated 4th Highest 8-Hour Ozone Concentration in Selected Cities in Burnet and Caldwell Counties

City 2006 Modeled 4th High Estimated 2012 4th High

Lockhart 77.32 ppb 69.78 ppb

Luling 76.04 ppb 68.62 ppb

Burnet 75.77 ppb 68.38 ppb

Marble Falls 77.35 ppb 69.80 ppb

If the standard is lowered to a level of 70 ppb, monitoring data showing the main population centers of

these areas being in attainment of the current standard might be sufficient to make a case that these

counties should be excluded from a prospective Austin nonattainment area.

All three of these maps also seem to show that there is an ozone regime in the eastern part of the

region – particularly eastern Williamson County – that appears to be independent of the ozone

generated by the Austin metropolitan area. The presence of the large Alcoa/Sandow facility just to the

east of this area in the southern tip of Milam County could be the cause of the elevated ozone levels in

this part of the region, although significant emissions changes have occurred since the 2006 time period.

CAPCOG also analyzed the plots for the daily average NOX concentrations. As was expected, CAMS 3

provides a much closer picture of peak 24-hour NOX concentrations than CAMS 38. However, the actual

peak NOX levels appear to be somewhat to the southeast of CAMS 3. Also, the Luling area consistently

has high modeled NOX concentrations, likely due to the presence of a compressor station, gas processing

plant, and oil and gas production equipment. The figure below shows one of the NOX plots created by

UT.

39

Table 17: Modeled Daily Average NOX Concentrations, June 28, 2006

The presence of significant NOX concentrations in the Luling area (even without accounting for the

significant increase in oil production in recent years) further supports the utility of monitoring ozone in

the Lockhart area between these elevated NOX concentrations and the Austin urban area.

Ultimately, the modeling results provide a useful way to visualize the adequacy of the current

monitoring network configuration to measure upwind and downwind ozone concentrations in the

region and to measure the physical extent of the ozone plumes generated from the urban core of

Austin. It is important to remember, however, that this is just one photochemical modeling episode

from seven years ago, so it might not be wise to optimize the monitoring network to capture exactly the

conditions present in the modeling episode. To the extent that the modeling results are consistent with

40

the region’s ozone conceptual model, the two sets of data provide more robust conclusions about the

monitoring network and can serve as a more robust basis for making recommendations for the network.

4.2: Emissions Inventory Analysis One bottom-up tool for analyzing monitoring needs is to analyze trends in the region’s emissions

inventory. What becomes clear in this analysis is that while most of the emissions from some of the

most important source categories have declined over the past 10-15 years, emissions from the oil and

gas sector, particularly in the area directly south of the Austin urban core, has increased dramatically in

recent years.

The following table represents an estimate of the change in the NOX emissions within the 5-county

Austin MSA from 2006 to 2012. The 2006 on-road emissions are based on the link-based emissions

inventories created by TTI for TCEQ in 2012, while the 2012 on-road emissions are based on statewide

non-link-based inventories created by TTI for TCEQ in 2011. The non-road emissions estimates are based

on 2006 and 2012 default TexN runs, TCEQ’s 2011 airport emissions inventory, TCEQ’s 2010 locomotive

inventory, and TCEQ’s 2009 drilling rig emissions inventory. The point source inventories are based on

the 2006 and 2010 point source emissions data collected by TCEQ. The area source emissions inventory

reflects TCEQ’s 2008 NEI inventory back-cast to 2006 and forecast to 2012 using their EGAS growth

factors. These factors do not account for the recent growth in the oil and gas sector.

Table 18: Estimated NOX Emissions in 2006 and 2012 in the Austin MSA (tons per day)

Source Category 2006 2012 Change

On-Road 69.21 46.84 -22.37

Non-Road 32.02 21.08 -10.94

Point 27.33 23.89 -3.44

Area 7.23 8.29 +1.06

Due to continued fleet turnover, the on-road and non-road emissions are expected to continue to

decrease in future years, and there appear to be no plans for new point sources within the Austin MSA

in the immediate future. As NOX emissions from these sources will continue to decrease, the role of NOX

emissions from point and area sources in local ozone formation would be expected to increase. The two

areas that continued upwind monitoring would be useful to track the impact of these sources on air

quality would be to the south in order to track impacts from oil and gas production and exploration and

to the northeast to track impacts from large coal-fired power plants.

Oil and gas exploration and production has increased dramatically to the south of the Austin urban core.

In Caldwell County, which is within the Austin MSA, oil production has increased from 938,159 barrels in

2008 to 1,512,962 barrels in 2012 – a 61% increase. Further south in the Eagle Ford Shale formation, the

increases have been even more dramatic. In eight counties to the south and southeast of the area

(Atascosa, Bee, De Witt, Gonzales, Karnes, Lavaca, Live Oak, and Wilson Counties), where TCEQ

estimates there was a total of 5,142 tons of NOX emitted from oil and gas production and exploration in

2008, oil production has increased from 2,704,210 barrels in 2008 to 72,812,836 barrels in 2012 – a

3,555% increase, and gas production has increased from 202,888,660 MCF in 2008 to 279,783,631 MCF

41

in 2012 – a 38% increase. While it is not clear exactly how much new emissions this activity is

generating, the scale of the increase in activity in recent years would be expected to result in significant

increases in NOX emissions in an area that is often upwind of the Austin area on high ozone days. The

area with the most growth – Karnes and De Witt Counties – are about 80 – 90 miles away from CAMS 3

in Austin, so by the time the emissions from these sources reach the Austin area, they may be

sufficiently dispersed along the extent of the production area that having an additional monitor in

Caldwell County may not provide much additional information on the influence of these areas beyond

what other existing monitors in Guadalupe, Hays, and Bastrop Counties could detect. However, the

additional 61% increase in production in Caldwell County, including in areas directly to the south and

east of Lockhart, make it a good candidate for locating a monitor in order to track the impact of the

growth in this sector on Austin’s air quality.

Table 19: Wells Permitted and Completed in the Eagle Ford Shale Play

Although emissions from the Sandow/Alcoa facility decreased significantly after 2006 (from 12,382 tons

of NOX per year in 2006 to 2,866 tons per year in 2012), the new Sandow 5 coal-fired power plant has

also begun operation in Milam County in 2010 and in 2012 emitted 4,021 tons of NOX, based on data

42

from EPA’s acid rain database. The combined emissions from these two facilities in a county adjacent to

the Austin MSA and immediately upwind of the region on many high ozone days makes continued

monitoring between these plants and the Austin MSA a priority. Such monitoring may prove essential to

documenting the contribution of these plants to the Austin CSA’s ozone .

4.3: Analysis of Mobile Surface Monitoring in 2011 Staff from UT conducted seven mobile monitoring trips during the ozone season in 2011 in which they

drove an SUV equipped with instruments to measure ozone, NOX, SO2, and total non-methane

hydrocarbon levels upwind and downwind of the Austin urban core. (The University of Texas at Austin,

2011). The objectives of the project were the following:

1. Mapping of pollution concentrations upwind and downwind of the Austin urban area and other

surrounding urban areas,

2. Mapping of pollution concentrations transported into the Austin area,

3. Mapping of pollution plumes transported into the Austin area,

4. Mapping of pollution concentrations over a large area where no monitors are currently present,

5. Mapping of pollution concentrations over a large area to determine if the ambient monitoring

stations are properly located.

The following figure shows an example of the results of the monitoring data collected during a portion

of one of the trips.

Figure 17: Examples of Surface Mobile Monitoring Data Collected in 2011

The monitoring trips provided some interesting and useful results that are useful for assessing the

adequacy of CAPCOG’s monitoring network to supplement TCEQ’s regulatory monitors by measuring

43

ozone levels upwind and downwind of the urbanized portions of the region. Among the results that

were useful for this assessment were:

Ozone plumes downwind of the Austin urban core are approximately 25 miles wide,

Ozone plumes downwind of the Austin urban core can extend much longer than expected, reaching as far away from the urban core as northeastern Burnet County and the northeast corner of Blanco County,

On the days with the highest ozone levels, upwind ozone levels can exceed 70 ppb, and

There are distinct, detectable industrial plumes that can impact ozone levels in the Austin area entering the region from the southeast, the northeast, and the north (industrial plumes were detected on 3 of the 7 trips).

The figure below shows one day for which the stationary sites would likely not have detected the

region’s maximum 8-hour ozone concentrations given the mobile monitor’s results.

44

Figure 18: Mobile Monitoring Data Compared to Max One-Hour Ozone Concentrations, August 29, 2011

The primary conclusions CAPCOG drew from this project as it relates to an assessment of the monitoring network are the following:

There is an ongoing need to operate stationary ozone monitors upwind of the Austin area both to document the elevated ozone levels that generally enter the region on high ozone days and to document cases in which distinct industrial plumes may be impacting regional ozone levels.

The distances between some of the region’s ozone monitors may prevent detection of ozone plumes entering the region or downwind plumes. CAMS 38 is 22 miles away from CAMS 614, CAMS 614 is 25 miles away from CAMS 1675, CAMS 1675 is 34 miles from CAMS 684, and CAMS 684 is 28 miles away from CAMS 6602. This leaves some fairly significant gaps in important upwind and downwind areas.

There is a need to monitor ozone levels further downwind of the Austin urban area when winds are combing from the south or southeast given the high ozone levels measured in eastern Burnet County and northwestern Williamson County.

CAMS 690: 91 ppb@ 12:00

CAMS 38: 82 ppb@ 12:00

CAMS 6602: 77 ppb@ 10:00

CAMS 614: 88 ppb@ 11:00

CAMS 3: 80 ppb@ 11:00

CAMS 684: 66 ppb@ 12:00

CAMS 675: 66 ppb@ 11:00

45

These conclusions are consistent with the analysis of the modeling results described earlier.

4.4: Temporary Monitoring in 2012 CAPCOG operated two temporary monitors during the 2012 ozone season that did not report to TCEQ’s

LEADS system. Instead, CAPCOG’s air quality monitoring contractor – Dios Dado – made weekly site

visits and downloaded the data directly from the ozone monitoring equipment during regular weekly

site maintenance and monthly calibrations, and provided CAPCOG with the raw data from the sites. Each

site was equipped with a Dasibi 1008 AH ozone analyzer, and R.M. Young Wind Speed/Wind Direction

sensor, and a Zeno data logger.

The two sites CAPCOG chose to perform this monitoring were at the Liberty Hill Fire Station (301 Texas

332 Loop, Liberty Hill, Texas) and the Elroy Public Library (13512 FM 812, Del Valle, Texas). These

locations were selected because they were directly downwind and upwind of the Murchison air quality

during high ozone days when winds were coming out of the south-southeast, which was the most

common resultant wind direction at CAMS 3 from 6:00 – 18:00 Central Standard Time (CST) during high-

ozone days (>=60 ppb) from 2001 - 2009 based on the region’s 2010 ozone conceptual model (The

University of Texas at Austin, July 2010). The Liberty Hill site was also selected based on the mobile

monitoring project’s results showing ozone levels further downwind of the Austin urban area than the

existing monitors would indicate. The Elroy site is also quite close to a location recommended by UT in

the monitoring network evaluation they conducted for CAPCOG in 2010 (The University of Texas at

Austin, October 2010). The graphic below shows the location of these two sites in relation to the

Murchison monitoring station and the other stationary monitors operating in 2012.

Figure 19: 2012 Ozone Monitoring Locations

46

Liberty Hill Results

The data collected at Liberty Hill suggest that although it is positioned more directly downwind of the

Austin urban area on many days than CAMS 38 and CAMS 690, both of these sites were better for

characterizing downwind ozone levels than Liberty Hill. The Liberty Hill site collected data from May 29,

2012, through November 1, 2012. During that time, its 4th highest daily 8-hour ozone average was 70.85

ppb, while the Audubon’s 4th highest average during that time was 72 ppb and the Lake Georgetown

monitor’s 4th high was 71 ppb. CAMS 38 recorded higher 8-hour ozone averages than Liberty Hill on 15

out of 23 days during which one or both monitors measured 8-hour ozone averages over 60 ppb, and

Audubon recorded more high ozone days outright than the Liberty Hill site at a 60 ppb, 65 ppb, 70 ppb,

and 75 ppb threshold. On average, the Audubon site recorded eight-hour ozone concentrations on that

were 0.77 ppb higher than the Liberty Hill site when either site recorded eight-hour ozone above 60

ppb. The Liberty Hill monitor did record one more day over 60 ppb than the Lake Georgetown monitor,

but it recorded fewer days over 65 ppb, 70 ppb, and 75 ppb. The average difference for all days when

either site measured 8-hour ozone over 60 ppb was 0.91 ppb. The correlations between elevated ozone

at the Liberty Hill site and CAMS 38 (0.61) and between Liberty Hill and Lake Georgetown (0.73) are

modestly high but not above 0.75, suggesting that monitoring at Liberty Hill would not necessarily be

duplicative of the monitoring occurring at CAMS 38 or CAMS 690.

Table 20: Comparison of Liberty Hill Monitoring Data to Nearby Stations, May 29 - November 1

Station 4th High Days > 60 ppb Days > 65 ppb Days > 70 ppb Days > 75 ppb

Liberty Hill 70.85 18 5 3 1

CAMS 38 72 20 7 4 3

CAMs 690 71 17 9 6 2

Elroy Results

The Elroy site collected data from June 27, 2012, through November 2, 2012. During this period, it

tended to have lower ozone levels than those measured at either CAMS 684 or CAMS 1675. Its fourth

highest daily 8-hour ozone average was 61.12 ppb, while the fourth highest daily averages at CAMS 684

and 1675 were 66 ppb and 69 ppb, respectively. Both CAMS 684 and CAMS 1675 recorded higher ozone

levels on all but one of the days that any of the three monitors measured 8-hour ozone averages of over

60 ppb. There was high correlation between the Elroy site and CAMS 1675 (0.75) and even higher

correlation between Elroy and CAMS 684 (0.88) on days when at least one of the three monitors

measured 8-hour ozone over 60 ppb. This suggests that locating a monitor in Elroy on a more

permanent may provide data that would be duplicative of the data collected at existing stations.

Table 21: Comparison of Liberty Hill Monitoring Data to Nearby Stations, May 29 - November 1

Station 4th High Days > 60 ppb Days > 65 ppb Days > 70 ppb Days > 75 ppb

Elroy 61.12 6 1 1 0

CAMS 684 66 10 4 2 1

CAMs 1675 69 11 6 3 1

47

4.5: Assessment of Monitoring Start and End Dates The seasonal distribution of high ozone days can help CAPCOG determine what the most appropriate

starting and ending dates are for its monitoring operations. These data also provide insight into the

relative importance of specific monitors in the region. For example, CAMS 6602 is often upwind and

CAMS 614 is often downwind of the Austin MSA during the types of high ozone days more common

from August – October, and CAMS 684 is positioned upwind of the Austin MSA during high ozone days

more common in May and June. Traditionally, CAPCOG has operated its monitors from mid-April to the

end of October. Since EPA is now considering setting the ozone standard in a range of 60 – 70 ppb and

there are sometimes 8-hour ozone averages measured at TCEQ’s year-round regulatory monitors in

Travis County, CAPCOG plotted the number of days that at least one monitor in Region 11 measured a

high ozone day at each of 4 thresholds between 2010 and 2012.

Figure 20: Seasonal Distribution of High Ozone Days 2010 - 2012

If the standard is lowered to 70 ppb or remains at 75 ppb, it appears that late April or early May would

be the appropriate time to begin monitoring, but if it is lowered to 65 ppb or 60 ppb, starting monitoring

earlier in April may be appropriate. If the standard remains at 75 ppb, it may not be necessary to

continue monitoring beyond mid-October, but if it is lowered, the end of October appears to be the

appropriate time to end monitoring.

For reference, CAPCOG identified the earliest and latest calendar dates high ozone levels have been

measured within the region in the table below.

Table 22: Earliest and Latest Calendar Dates with High-Ozone Days Measured

Threshold Earliest Latest

>60 ppb February 14 November 17

>65 ppb February 14 November 17

0.0%

5.0%

10.0%

15.0%

20.0%

25.0%

30.0%

35.0%

>60 ppb

>65 ppb

>70 ppb

>75 ppb

48

Threshold Earliest Latest

>70 ppb March 23 November 17

>75 ppb March 23 October 23

Section 5: Conclusions and Recommendations Based on the analyses in the prior sections of this report, CAPCOG makes the following

recommendations:

CAPCOG should continue operating all six of the existing monitoring stations in 2013 starting on April 15 and ending on October 31,

CAPCOG should establish a temporary monitoring station in southwest Austin for 2013 and TCEQ should consider establishing a third permanent regulatory monitor in that region at some point in the future if CAPCOG’s temporary monitor measures significant levels of ozone as are suggested by modeling,

CAPCOG should establish a temporary monitoring station in Lockhart for 2013, and

CAPCOG and TCEQ should re-evaluate monitoring needs for the region after the budget for FY 2014 is set and EPA issues its proposal for a new ozone standard.

CAPCOG’s recommendation not to move or shut down any of the existing sites is based on a number of

factors. First of all, the importance of CAPCOG’s monitoring network in measuring the region’s

maximum ozone concentrations has increased in recent years – with CAMS 614 now having a design

value as high as the region’s controlling regulatory monitor and CAMS 1675 and 690 often measuring

the region’s highest 8-hour ozone average in recent years. CAMS 601, CAMS 684 and CAMS 6602 remain

vital tools in characterizing upwind ozone levels. Furthermore, Travis County has already approved

funding for CAPCOG to specifically operate CAMS 601 and 684 in order to continue obtaining data on

upwind ozone concentrations. Given the data collected at the other four monitoring stations in recent

years and the fact that none of the stations have a high correlation with one another, CAPCOG believes

that shutting down or moving any of these four would not be prudent until there is more clarity on what

the new ozone standard is likely to be. Moreover, CAPCOG’s experiences in 2011 establishing CAMS

6602 and 1675 as new permanent monitoring sites and in 2012 establishing temporary sites at Liberty

Hill and Elroy have provided a useful context for understanding the significant amount of time required

to get the necessary clearances to set up any new monitoring station, so moving any existing station to a

new site would run the risk of missing some valuable data early in the ozone season. And while there are

some days when high ozone is measured outside of the April 15 to October 31 window, since these are

research monitors, the incremental benefit of capturing data outside of that window would not be

worth the added cost until there was more certainty as to what the future ozone standard will be.

CAPCOG’s recommendation for establishing a temporary monitoring station in southwest Austin is

based on data from the conceptual model and the photochemical modeling for the June 2006 ozone

episode that both showed that the current monitoring network would not be able to adequately

measure high ozone in the region when winds are coming out of the northeast. The modeling results

especially highlight this gap – there were 10 – 15 ppb differences in the ozone levels at the current

stations and the peak ozone in those downwind plumes on June 3, 2006 and June 13, 2006. A

49

monitoring station in southwest Austin would also provide more balanced population coverage for the

region – currently CAMS 3 is the primary station representing ozone levels for the whole city of Austin

most of the time, so a monitoring station to the south would help provide people in South Austin data

more directly relevant to their own area. CAPCOG’s recommendation that TCEQ eventually establish a

permanent regulatory monitor in this vicinity is highlighted by the two distinct types of meteorological

regimes in which the region experiences ozone – winds from the south to southeast, and winds from the

northeast. CAMS 3 and 38 are positioned well to measure the region’s maximum 8-hour ozone

concentration and monitor compliance with the NAAQS on days when winds are coming out of the

southeast, but not on days when winds come out of the northeast. In order to have confidence that the

regulatory monitors in the region are actually capturing the maximum ozone levels measured in the

region, at least one monitoring station to the southwest of Central Austin would be needed. This is also

an area that UT recommended CAPCOG monitor in its 2010 network assessment.

CAPCOG’s recommendation to establish a temporary monitoring station in Lockhart is based on multiple

factors – 1) the need to track the impact of the increased oil and gas production south of Austin on the

region’s air quality, 2) the need to detect any ozone plumes entering the region between CAMS 1675

and CAMS 684, 3) the need to provide better coverage of Caldwell County and its communities than the

current network provides, and 4) to begin documenting the air quality within Caldwell County to

potentially assist it in avoiding inclusion in an Austin nonattainment area if the region is ever considered

for an ozone nonattainment designation. While high ozone days don’t occur as often when winds come

out of the south as they do on days when winds come out of the southeast or northeast, the staggering

scale of the growth in oil and gas exploration and production to the south of the region – the one source

type that is experiencing growth in NOX emissions – has the potential for making the ozone levels when

winds do come from the south substantially higher, and the current monitoring configuration may not

be sufficient to track these conditions. Caldwell County is also in its own right a member of the Clean Air

Coalition – a group of local elected officials who conduct regional ozone planning – but it is the only

county in the 5-County MSA without its own monitor. Aside from Martindale, the population centers of

Lockhart and Luling are quite far away from any ozone monitors. Having a monitoring station in Lockhart

would provide the population of Caldwell County more relevant data on air quality within Caldwell

County than the closest monitors would, and it would also provide data that could be useful if and when

EPA makes nonattainment designations. The modeling tiles prepared by UT and the summary maps

created by CAPCOG showed that there were a significant number of days when the modeled ozone

levels in Caldwell County were below 60 ppb while in other parts of the region they exceeded 60 ppb

and often ozone levels in Caldwell County were significantly lower than the rest of the region. A

temporary monitor in Lockhart would serve a number of CAPCOG’s monitoring goals.

CAPCOG did not make specific recommendations for the monitoring network beyond 2013 for two

important reasons – there is great uncertainty as to the availability of funding for monitoring beyond the

2013 ozone season and the optimal monitoring configuration would likely change depending on the

revised ozone standard. The TCEQ’s Legislative Appropriation Request for the 2014-2015 biennium did

not include any funding for the Rider 8 Grant beyond what was appropriated for the 2012-2013

biennium, which represented a 50% cut from 2010-2011 levels. At the level requested by TCEQ,

assuming each area received proportionately the same amount of money, the annual appropriation

50

would exceed the CAPCOG Air Quality Program’s current operating expenses even without operating

any monitoring stations or conducting any contracting at all. Local governments in the region have

provided some funding in 2012 and 2013 to support CAPCOG’s monitoring program, including

purchasing over $35,000 worth of equipment in 2012 and funding the operation of two monitoring

stations for $15,000 in 2013. However, there is no long-term mechanism through with the local

governments have agreed to support CAPCOG’s monitoring program beyond these steps and until they

determine what if any level of support to provide, there is no way to know what level of resources will

be available from local government either. Until the summer of 2013 when the funding situation for

2014 becomes clearer, CAPCOG’s air quality program will not be able to assess its capacity for fielding air

monitoring stations in the future. It likely would also be worthwhile to wait until EPA issues its proposal

for a new ozone standard. The EPA administrator was prepared to lower the primary standard to 70 ppb

using the same form as the current standard and to set a new secondary standard in September 2011,

but that proposal was withdrawn. While expectations are that the proposed new standard will also be

set at least as low as 70 ppb, there are significant differences in the frequency with which high ozone

occurs throughout the region depending on where the standard is set, and knowing at least the range of

the proposed standard would help narrow down the set of options CAPCOG should consider as part of a

future assessment.

There are three other areas that monitoring would be useful but which CAPCOG is not recommending

for monitoring for 2013. These are: Lake Travis, the Manor/Elgin area, and Burnet County. The 2006

modeling and the region’s conceptual model indicate that the Lake Travis area may have the highest

eight-hour ozone concentrations in the region on some days, especially when winds come into the

region from the east. Unlike most residential or commercial areas of the region where typical outdoor

ozone exposure would likely be limited, the Lake Travis area has lots of outdoor recreational activity that

can occur over many hours each day during ozone season. This could put boaters and hikers at risk of

extended exposure to unhealthy levels of ozone on certain days. However, the existing regulatory

monitors at Murchison Middle School and the Austin Audubon Society are close enough to these areas

(less than 10 miles away) that they should provide enough of an indication that high ozone is being

measured in the region that an additional monitor in Lake Travis may be duplicative of the information

collected at those two sites. Moreover, while it appears that if the standard remains at 75 ppb, a

monitor to the west of CAMS 3 might be warranted, if the standard is lowered to 70 ppb, the

importance of this area decreases significantly compared to other areas in the region with more limited

monitoring coverage, such as central Hays County, western Williamson County, and eastern Williamson

County.

One of the areas that UT recommended CAPCOG establish a monitor in its 2010 assessment was the

Manor/Elgin vicinity. This area is about equidistant between CAMS 6602 and CAMS 684 – about 14 miles

on either side of US 290, and it is more frequently downwind of the Sandow power plant in Milam

County than CAMS 6602 is. This area is also approximately due East of CAMS 3 and since the conceptual

model and June 2006 photochemical modeling indicate that winds come out of the east proportionately

more of the days when CAMS 3 measures 8-hour ozone over 75 ppb than when the threshold is lower, it

may yet be useful to monitor that area. However, given the limited resource for monitoring in 2013,

CAPCOG felt that it was less important to monitor this area than southwest Austin and Lockhart, and

51

that CAMS 6602 is already positioned relative to CAMS 3 in a direction more common for high ozone

measured at CAMS 3 if the standard is lowered.

Finally, for reasons already discussed, CAPCOG does not plan on conducting any ozone monitoring in

Burnet County unless and until the local elected officials are comfortable with CAPCOG doing so,

although from a regional perspective, the value of using limited monitoring resources in Burnet County

is questionable compared to the value of conducting monitoring to meet other needs. The only goals

monitoring in Burnet County would serve right now would be to demonstrate compliance with the

NAAQS and provide monitoring data more relevant to the local communities in Burnet County. Despite

the social utility of a monitoring station in Burnet County given its inclusion in a default Austin

nonattainment area, such a monitoring station would likely be of little scientific value in characterizing

upwind and downwind ozone concentrations within the region.

Whatever the configuration of the regional ozone monitoring network looks like in the future, CAPCOG’s

monitoring network should reflect the priorities of local stakeholders. Some of CAPCOG’s monitors – like

CAMS 601 and CAMS 614 – have been operated over long periods of time and are useful for tracking

long-term trends, but may not be ideally positioned to measure upwind or downwind air quality for the

region. In order to strike a balance between competing goals and to optimize the limited resources

available to CAPCOG for conducting monitoring, it will be important over the next year to work with

TCEQ, the local governments, and other stakeholders to ensure that all monitoring resources being used

in the region are being optimally used to meet the region’s monitoring goals moving forward.

52

Works Cited Dios Dado. (February 2012). Operation of Continuous Air Quality Monitoring Stations in the CAPCOG

Region, 2012 Ozone Season.

The University of Texas at Austin. (2011). Surface Mobile Monitoring in the Austin Area for 2011.

Retrieved from http://www.capcog.org/documents/airquality/reports/2011/Austin-

_Surface_Mobile_Monitoring_2011.pdf

The University of Texas at Austin. (2012). Conceptual Model for Ozone in the Austin Area. Retrieved from

http://www.capcog.org/documents/airquality/reports/2012/Austin_Area_Conceptual_Model_2

012.pdf

The University of Texas at Austin. (April 2012). Ambient Monitoring Projects - Surface Mobile Monitoring.

Retrieved from http://www.capcog.org/documents/airquality/reports/2011/Austin-

_Surface_Mobile_Monitoring_2011.pdf

The University of Texas at Austin. (July 2010). Ozone Conceptual Model for the Austin Area. Retrieved

from

http://www.capcog.org/documents/airquality/cac/2010/september2010/Austin_CM_ver21.pdf

The University of Texas at Austin. (October 2010). Evaluation and Recommendations for the Austin Area

Ozone Monitoring Network. Retrieved from

http://www.capcog.org/documents/airquality/reports/2010/Austin_monitor_evaluation.pdf

U.S. Census Bureau. (2012). Tiger/Line Shapefiles Pre-joined with Demographic Data.

U.S. Environmental Protectino Agency. (February 2007). Ambient Air Monitoring Network Assessment

Guidance. Retrieved from

http://www.epa.gov/ttnamti1/files/ambient/pm25/datamang/network-assessment-

guidance.pdf

53

EPA’s guidance recommends analyzing at any correlations of over 0.75. Monitor pairings with over 0.75

correlation included:

Audubon (CAMS 38) – Murchison (CAMS 3) correlation = 0.81 when Audubon was >60 ppb (36 days total; inverse correlation = 0.70)

McKinney Roughs (CAMS 684) – San Marcos (CAMS 1675) correlation = 0.81 when McKinney Roughs was > 60 ppb (20 days total; inverse correlation = 0.61)

Lake Georgetown (CAMS 690) – Hutto (CAMS 6602) correlation = 0.76 when Lake Georgetown was > 60 ppb (27 days total; inverse correlation = 0.72)

Elroy – McKinney Roughs (CAMS 684) correlation = 0.93 when Elroy was > 60 ppb (6 days total; inverse correlation = 0.64)

Elroy – San Marcos (CAMS 1675) correlation = 0.79 when Elroy was > 60 ppb (6 days total; inverse correlation = 0.58)

Since the Elroy monitor was not in operation during much of the early part of the 2012 ozone season

and the correlations are only based on 6 days of data, the high correlations with monitoring the San

Marcos and McKinney Roughs sites may provide much insight into its value. However, to the extent that

all three of these stations should measure “background” ozone concentrations on high-ozone days in

Travis County when winds come out of the southeast this would make sense. The McKinney Roughs

monitor’s high correlation with the San Marcos monitoring on days when McKinney had high ozone

levels is also consistent with this analysis. However, the fact that inverse correlation – when San Marcos

8-hour averages were above 60 ppb – resulted in a correlation of only 0.61 indicates that while the San

Marcos monitor may be able to substitute for the McKinney Roughs monitor, the reverse is not true.

The moderately high correlation between the monitoring values at the Lake Georgetown and Hutto

monitors and the similarity in both directions (0.76 and 0.72) may suggest some duplication in the data

from these monitors. The Lake Georgetown monitor should be able to pick up downwind ozone

concentrations for the metropolitan area when winds are coming out of the south, while the Hutto

monitor should be able to pick up downwind ozone concentrations when winds come out of the south-

southwest – which is less common but can help differentiate the impact of the Austin area’s emissions

from the San Antonio area’s emissions on those days. Both of these sites are sited in locations that

should also be able to detect upwind ozone concentrations when winds come out of the north to

northeast. Hutto in particular is sited to help detect power plant plumes from the large number of coal-

fired power plants to the east and northeast of Williamson County. To the extent that

54

Appendix A: Selected Back-Trajectories for Liberty Hill and Elroy

Temporary Monitoring Stations 2012 CAPCOG produced back-trajectories using the National Oceanic and Atmospheric Administration’s

(NOAA’s) HYSPLIT program for each day that the Liberty Hill or Elroy monitor measured an 8-hour ozone

concentration of over 60 parts per billion during CAPCOG’s temporary monitoring at those locations in

the 2012 ozone season. CAPCOG ran 24-hour back trajectories starting at 22:00 Universal Time Code (

16:00 Central Standard Time) at three heights: 0 meters, 500 meters, and 1,000 meters above ground

level. The following table shows the dates and maximum 8-hour ozone concentrations for each site that

CAPCOG prepared a back-trajectory for.

Table 23: Dates when Temporary Monitors Measured Maximum 8-Hour Ozone Averages Over 60 ppb

Date Liberty Hill (ppb) Elroy (ppb)

June 1, 2012 71 N/A

June 9, 2012 61 N/A

June 23, 2012 62 N/A

June 25, 2012 66 N/A

June 26, 2012 65 N/A

June 27, 2012 78 N/A

June 28, 2012 66 52

August 7, 2012 64 55

August 8, 2012 61 43

August 10, 2012 75 41

August 11, 2012 75 61

August 20, 2012 68 70

September 10, 2012* 63 61

September 20, 2012* 66 58

September 21, 2012* 63 58

October 3, 2012* 61 58

55

Figure 21: Liberty Hill Back-Trajectory for June 1, 2012

56


57


58


59


60


61


62

Figure 28: Liberty Hill Back-Trajectories for August 7, 2012

63


64


65


66


67


68


69


70

Figure 36: Liberty Hill Back-Trajectory for August 29, 2012

71


72


73

Figure 39: Liberty Hill Back-Trajectories for September 10, 2012

74

Figure 40: Liberty Hill Back-Trajectory for September 11, 2012

75


76


77

Figure 43: Liberty Hill Back-Trajectories for October 3, 2012

78

Figure 44: Elroy Back-Trajectories for August 11, 2012

79


80


81

Figure 47: Elroy Back-Trajectories for September 10, 2012

82


83


84

Figure 50: Elroy Back-Trajectories for October 3, 2012

85

Appendix B: Complete 8-Hour Ozone Averages for Temporary Sites The table below provides the calculated 8-hour ozone averages for the Liberty Hill and Elroy Sites for

every day from May 29, 2012 through November 2, 2012. CAPCOG calculated the data using raw data

outputs that were downloaded from the sites weekly by Dios Dado staff, and applied slope and intercept

corrections using calibrations performed by Dios Dado.

Table 24: Maximum Daily 8-Hour Ozone Averages at Liberty Hill and Elroy Stations, 2012

Date Liberty Hill Elroy

29-May-12 46 NA

30-May-12 40 NA

31-May-12 56 NA

1-Jun-12 71 NA

2-Jun-12 59 NA

3-Jun-12 35 NA

4-Jun-12 53 NA

5-Jun-12 59 NA

6-Jun-12 56 NA

7-Jun-12 51 NA

8-Jun-12 54 NA

9-Jun-12 61 NA

10-Jun-12 53 NA

11-Jun-12 44 NA

12-Jun-12 35 NA

13-Jun-12 40 NA

14-Jun-12 33 NA

15-Jun-12 33 NA

16-Jun-12 31 NA

17-Jun-12 41 NA

18-Jun-12 54 NA

19-Jun-12 46 NA

20-Jun-12 27 NA

21-Jun-12 43 NA

22-Jun-12 54 NA

23-Jun-12 62 NA

24-Jun-12 55 NA

25-Jun-12 66 NA

26-Jun-12 65 NA

27-Jun-12 78 54

28-Jun-12 66 52

29-Jun-12 53 43

86


30-Jun-12 38 32

1-Jul-12 32 26

2-Jul-12 31 27

3-Jul-12 33 28

4-Jul-12 30 27

5-Jul-12 35 29

6-Jul-12 42 27

7-Jul-12 43 35

8-Jul-12 40 25

9-Jul-12 32 40

10-Jul-12 44 31

11-Jul-12 42 34

12-Jul-12 50 49

13-Jul-12 46 38

14-Jul-12 44 42

15-Jul-12 40 35

16-Jul-12 35 32

17-Jul-12 32 23

18-Jul-12 26 22

19-Jul-12 34 23

20-Jul-12 32 31

21-Jul-12 42 34

22-Jul-12 38 25

23-Jul-12 35 27

24-Jul-12 35 26

25-Jul-12 38 24

26-Jul-12 33 24

27-Jul-12 35 24

28-Jul-12 35 27

29-Jul-12 53 39

30-Jul-12 48 31

31-Jul-12 53 34

1-Aug-12 50 32

2-Aug-12 47 32

3-Aug-12 41 33

4-Aug-12 35 25

5-Aug-12 35 25

6-Aug-12 54 49

7-Aug-12 64 55

87


8-Aug-12 61 43

9-Aug-12 57 42

10-Aug-12 75 41

11-Aug-12 75 61

12-Aug-12 62 38

13-Aug-12 47 44

14-Aug-12 47 37

15-Aug-12 35 27

16-Aug-12 33 25

17-Aug-12 37 29

18-Aug-12 33 27

19-Aug-12 35 37

20-Aug-12 68 70

21-Aug-12 58 57

22-Aug-12 56 56

23-Aug-12 58 49

24-Aug-12 48 34

25-Aug-12 32 28

26-Aug-12 32 25

27-Aug-12 29 37

28-Aug-12 54 49

29-Aug-12 60 57

30-Aug-12 60 53

31-Aug-12 61 51

1-Sep-12 47 29

2-Sep-12 34 33

3-Sep-12 36 33

4-Sep-12 44 34

5-Sep-12 49 32

6-Sep-12 51 32

7-Sep-12 53 38

8-Sep-12 50 50

9-Sep-12 51 51

10-Sep-12 63 61

11-Sep-12 66 54

12-Sep-12 53 44

13-Sep-12 32 19

14-Sep-12 25 20

15-Sep-12 34 37

88


16-Sep-12 26 26

17-Sep-12 37 45

18-Sep-12 46 47

19-Sep-12 55 48

20-Sep-12 61 58

21-Sep-12 63 58

22-Sep-12 56 44

23-Sep-12 54 37

24-Sep-12 52 45

25-Sep-12 47 43

26-Sep-12 45 42

27-Sep-12 42 38

28-Sep-12 33 26

29-Sep-12 25 21

30-Sep-12 35 40

1-Oct-12 43 43

2-Oct-12 41 44

3-Oct-12 61 58

4-Oct-12 49 46

5-Oct-12 50 45

6-Oct-12 37 33

7-Oct-12 26 28

8-Oct-12 38 36

9-Oct-12 43 41

10-Oct-12 39 29

11-Oct-12 26 19

12-Oct-12 33 24

13-Oct-12 24 20

14-Oct-12 38 36

15-Oct-12 42 39

16-Oct-12 36 31

17-Oct-12 32 40

18-Oct-12 43 46

19-Oct-12 53 45

20-Oct-12 42 39

21-Oct-12 31 31

22-Oct-12 32 32

23-Oct-12 35 34

24-Oct-12 38 35

89


25-Oct-12 35 32

26-Oct-12 26 22

27-Oct-12 31 34

28-Oct-12 38 41

29-Oct-12 42 44

30-Oct-12 53 48

31-Oct-12 45 43

1-Nov-12 43 41

2-Nov-12 NA 39

90

Appendix C: June 2006 Photochemical Modeling Episode Plots and Data Accompanying this report is a memo prepared by the University of Texas with graphical plots of all of

the days in the June 2006 ozone episode when somewhere within the Austin CSA modeled or measured

an 8-hour ozone concentration over 60 ppb. There is also an accompanying data set provided by UT that

was used for some of the maps CAPCOG generated.

capcog 2013 monitoring network assessment

Documents