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You are here: Home / Publications / Periodicals / Natural Outlook / Fall 2010 / A Commitment to Air Quality in the Barnett Shale

A Commitment to Air Quality in the Barnett Shale

The state devotes extensive resources to the Barnett Shale area in North Texas. (Natural Outlook, Fall 2010)

Air Monitor in the Barnett Shale area of Texas.
Monitoring results, health-effect evaluations, and other documents pertaining to the TCEQ’s efforts in the Barnett Shale area are posted on the TCEQ website.

The Barnett Shale area in North Texas has received a lot of attention recently, as some residents have expressed misgivings about oil and gas operations. The story has been covered heavily by the media, and residents have brought their questions to federal, state, and local government agencies.

“In response to these concerns, the TCEQ has committed a tremendous amount of time and resources to the issue of Barnett Shale air quality, and we will continue to do so,” says Chairman Bryan Shaw, Ph.D. “After several months of operation, state-of-the-art, 24-hour air monitors in the Barnett Shale area are showing no levels of concern for any chemicals. This reinforces our conclusion that there are no immediate health concerns from air quality in the area, and that when they are properly managed and maintained, oil and gas operations do not cause harmful excess air emissions.”

Formation Is Rich in Natural Gas

The Barnett Shale geological formation is in a 23-county area that lies to the west, northwest, and southwest of the DFW area. Rich in natural gas, the formation has witnessed a massive expansion of oil and gas activities in the last several years. Approximately 14,000 gas wells have been drilled, producing approximately 4.8 billion cubic feet of natural gas per day. The Barnett Shale may very well contain some 26 trillion cubic feet of natural gas—a resource that could help meet the energy needs of the State of Texas and other parts of the nation.

Proximity to Production Has Caused Concern

Portions of the Barnett Shale lie under urban and suburban areas, which means that some of the natural gas operations and facilities are close to homes and other structures. This proximity has caused some area residents to become concerned about potential health effects. Consequently, as production has risen, complaints to federal, state, and local agencies, including the TCEQ, have increased.

Oil and gas operations in Texas are regulated by the Texas Railroad Commission; however, the TCEQ is responsible for permitting some of the equipment used in these operations and associated air emissions.

TCEQ Assesses Air Quality in Barnett Shale Area

Due to concerns about the effect of oil and gas operations on ozone levels in the Dallas–Fort Worth area, in 2007 the TCEQ began surveying the rapidly expanding Barnett Shale natural gas operations. Through a series of helicopter flyovers, the agency assessed the number of compressors operating in the area. These flights, along with subsequent studies, determined that—due to the location of the operations and the prevailing wind direction—emissions from oil and gas operations in the Barnett Shale area were not a significant factor in Dallas–Fort Worth ozone levels. However, with the EPA promulgating new, much lower ozone standards, these operations will again be examined to see if they can play a part in helping to meet the new standards.

In order to assess the air quality in the Barnett Shale area, and determine whether there was any scientific evidence of threats to public health, in 2009 and 2010 the TCEQ conducted several large, in-depth surveys of air quality in the six counties surrounding Fort Worth. The TCEQ deployed teams of air monitoring experts into the area to conduct the surveys. Staff used GasFind IR cameras (which show emissions that are invisible to the naked eye), handheld instruments to measure VOCs (volatile organic compounds), van-mounted gas chromatograph analyzers, SUMMA air sampling canisters, and their own senses to look for and measure emissions from oil and gas operations.

Although gas chromatograph analyzers and SUMMA canisters measure many VOCs, some of which are air toxics, TCEQ toxicologists have determined that benzene is the key air contaminant of concern. If benzene levels from oil and gas facilities are below levels of concern, other air toxics should be as well.

From Aug. 1, 2009, to June 30, 2010, the TCEQ surveyed more than 560 sites using the GasFind IR camera. At approximately 450 of these sites, a handheld VOC sampler was also used. Based on observations with these instruments, 319 canister samples have been collected. In addition, samples have been collected via mobile Real-Time Automated Gas Chromatograph.

Out of all the samples taken, the TCEQ has only found two instances of benzene exceeding short-term levels of concern. Subsequent sampling at these two locations has shown low levels of benzene.

Monitoring Results Available on TCEQ Website

In an effort to demonstrate transparency and help the public understand the issues, monitoring results, health-effect evaluations, and other documents pertaining to the TCEQ’s efforts in the Barnett Shale area are posted on the TCEQ website, at Barnett Shale Geological Area.

In order to comprehend the issue of air emissions in the Barnett Shale area, it is important to understand two numbers that are used to assess the potential for adverse health effects from exposure to benzene: 180 ppbv (parts per billion by volume) and 1.4 ppbv. The first number, 180 ppbv, is the short-term air monitoring comparison value for benzene. This number is conservative and it is unlikely that adverse health effects would occur if someone were to be exposed to this concentration of benzene for a short period of time (one hour). The second number, 1.4 ppbv, is the long-term air monitoring comparison value for benzene. Someone exposed to this level 24 hours a day for 70 years would not be expected to experience adverse health effects.

“Our studies and samples are leading us to conclude that oil and gas operations, when properly managed and maintained, should not cause harmful emissions,” says Commissioner Buddy Garcia. “When staff sees a sample that causes concern, we quickly identify the cause of the emissions and it is fixed. We continue to diligently monitor air quality, vigorously investigate complaints, and take necessary enforcement actions to help ensure compliance.”

TCEQ Installs Monitors

“One of the primary lessons we have learned is the need for long-term air monitoring data,” says Commissioner Carlos Rubinstein. “Simply taking an instantaneous air sample, and then trying to draw conclusions about a long-term health concern, is an inappropriate comparison, and is also made all the more difficult when dealing with measured amounts of chemicals that are very low.”

So the TCEQ added two new long-term monitors in the Barnett Shale area, and will install three more in the near future.

In the spring of 2009, the TCEQ installed automated gas chromatograph (AutoGC) monitors in two locations that are surrounded by natural gas operations—the town of DISH, in Denton County, and near Eagle Mountain Lake, in Tarrant County. These monitors operate around the clock, measuring levels of more than 45 VOCs, including benzene. After months of continuous operation, there have been no chemicals measured above levels of concern. The results from the monitors are posted hourly on the TCEQ website, at Barnett Shale Geological Area.

The same holds true of two already existing fixed-site VOC monitors in Fort Worth and Denton, which have shown no increase in benzene levels as natural gas operations in the Barnett Shale area have grown over the years.

The TCEQ will install three more new AutoGC monitors: one in Flower Mound, one in Tarrant County, and another in a location yet to be determined. These monitors, which cost as much as $250,000 for the first year and $100,000 per year thereafter, will also have their results posted online.

In addition, monitoring surveys in Fort Worth have found no immediate levels of concern for benzene. The City of Fort Worth is planning to conduct an independent monitoring survey of its own in the near future.

TCEQ Addresses Concerns, Launches Outreach Efforts

Much of the concern about natural gas operations has been centered in DISH, so in early 2009, the Texas Department of State Health Services performed blood tests on 28 DISH residents (representing about 13 percent of the town’s population). Test results showed that the exposure of DISH residents to VOCs was similar to that of the general U.S. population, and that exposure to certain contaminants was no higher than that of the general U.S. population. The study further found that the only residents who had higher levels of benzene in their blood were smokers. Cigarette smoke contains benzene, so finding this in smokers’ blood is not unusual, the department noted.

At the same time that it addressed the concerns of residents in the Barnett Shale area, the TCEQ launched an ongoing outreach effort to oil and gas associations and operators in the area. Efforts included educating the industry on current rules and on the importance of proper operational maintenance.

The Path Forward

Today, the TCEQ continues a multipronged effort to assess the air quality in the Barnett Shale area, and reduce emissions, with the goal of ensuring that the air is safe to breathe.

One important effort is to increase the quality and quantity of long-term air monitoring in the area. Although short-term sampling is useful, and can help determine if a particular site is emitting excess emissions, long-term air monitoring is needed to determine the overall air quality and air quality trends in the area.

The TCEQ regional office in Fort Worth has added seven new air inspectors to respond to air quality complaints quickly. In most cases, responses to complaints are handled within a few hours of receipt.

The TCEQ is also in the process of amending its rules that authorize oil and gas facility equipment. The new rules will update administrative and technical requirements, and will include enforceable monitoring, sampling, and record-keeping requirements. The new rules will help the agency ensure that these oil and gas facilities are properly operated and maintained in order to be protective of public health and welfare, and will allow the agency to effectively focus resources on facilities that produce significant emissions.

Even though TCEQ air monitoring indicates that ambient air in the Barnett Shale area poses no immediate health concerns, the agency will continue to focus on the area, taking measures to improve air quality and ensure that the air is safe to breathe.


Dallas–Fort Worth Ozone Design Values Compared to Barnett Shale Natural Gas Production


Gas production increased between the years 1999 and 2009. The eight-hour ozone value declined. Data is in the table below.

Gas Production
YearGas Produced
(billion cubic feet per year)
Eight-Hour Ozone Design Value
(parts per billion)
1999 41 101
2000 79 102
2001 135 101
2002 221 99
2003 304 100
2004 380 98
2005 503 95
2006 717 96
2007 1,103 95
2008 1,610 91
2009 1,773 86

Benzene Averages


The annual benzene averages from Augo-GC air monitors in the Dallas-Fort Worth-Barnett Share area are substantially lower than the long-term air monitoring comparison value (AMCV) of 1.4 ppbv. The results from the monitors are posted hourly on the TCEQ website.

The annual benzene averages from Augo-GC air monitors in the Dallas-Fort Worth-Barnett Share area are substantially lower than the long-term air monitoring comparison value (AMCV) of 1.4 ppbv. Data is in the table below.

Auto GC Benzene Annual Averages
YearDallas
Benzene Concentration
(ppbv)
Fort Worth
Benzene Concentration
(ppbv)
DISH
Benzene Concentration
(ppbv)
Eagle Mountain
Benzene Concentration
(ppbv)
2000 0.23      
2001 0.25      
2002 0.3      
2003 0.23 0.23    
2004 0.19 0.22    
2005 0.14 0.24    
2006 0.2 0.18    
2007 0.17 0.2    
2008 0.17 0.16    
2009 0.17 0.16    
2010 0.21 0.18 0.12 0.06

2009-2010 Monthly Benzene Averages
YearDallas
Benzene Concentration
(ppbv)
Fort Worth
Benzene Concentration
(ppbv)
DISH
Benzene Concentration
(ppbv)
Eagle Mountain
Benzene Concentration
(ppbv)
Aug 09 0.1 0.1    
Sep 09 0.13 0.15    
Oct 09 0.15 0.15    
Nov 09 0.32 0.23    
Dec 09 0.3 0.21    
Jan 10 0.31 0.24    
Feb 10 0.27 0.22    
Mar 10 0.2 0.17    
Apr 10 0.18 0.16 0.14 0.08
May 10 0.15 0.14 0.13 0.06
Jun 10 0.10 0.08 0.09 0.03
Jul 10 0.14 0.10 0.10 0.04

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