Press release from the Texas Commission on Environmental Quality re: their air quality study in the Barnett Shale:
TCEQ COMPLETES STUDY OF AIR EMISSIONS IN BARNETT SHALE
Most readings well below acceptable exposure levels – two hot spots identified and corrected
The Texas Commission on Environmental Quality (TCEQ) has announced the results of its study of air quality in the Barnett Shale area of North Texas. A total of 94 oil and gas monitoring sites were surveyed. At a majority of the monitoring sites, chemicals were either not detected or were detected below levels of health concern. However, two monitoring sites had relatively high levels of benzene. In addition, 19 monitoring sites registered benzene concentrations higher than the TCEQ would like to see.
The study analyzed more than a hundred volatile organic compounds (VOCs), but mainly focused on benzene, which is a human carcinogen.
Although the results are complex, it is clear that gas production facilities can, and in some cases do, emit contaminants in amounts that could be deemed unsafe for life-time (70 years) or long-term exposure. However, at only two monitoring sites were benzene levels found that would trigger immediate actions to reduce emissions.
At one monitoring site, the Targa North Texas LP Bryan Compressor Station (monitoring site 8 ), instantaneous benzene samples were collected at levels up to 1,100 parts per billion (ppb) approximately 200 yards from two residences. Although these levels are less than the lowest levels shown to cause adverse health effects in short-term human and animal studies, the levels are of potential concern due to their contribution to long-term cumulative exposure levels. The TCEQ provided the monitoring results to Targa and the company reported that repairs had been completed. In testing done the week of Jan. 18, VOC levels were below short-term effects screening levels (ESLs), and benzene was at normal background levels, about .25 ppb.
In another measurement at a Devon Energy natural gas well (monitoring site 7), a sample was collected with a benzene concentration of 15,000 ppb. Although this sample was collected at the well-head and the general public would not be expected to be exposed to these levels, it clearly demonstrates that gas operations can contribute to benzene concentrations in ambient air. The TCEQ provided the monitoring results to Devon and the company reported that repairs had been completed. Like monitoring site 8, testing done the week of Jan. 18 showed VOC levels at the well-head and at the fence line were below short-term effects screening levels, and benzene was at normal background levels, about .25 ppb.
The study also found elevated levels of other VOCs, including carbon disulfide, ethane, 1,2-dibromoethane, and isopentane, but none at levels that would be expected to cause adverse health effects. In addition, several other compounds that can cause odors were detected.
• The TCEQ has already instituted new complaint and investigation
guidelines for oil and gas production areas that will see citizen complaints investigated within 12 hours. Investigations can result in enforcement actions against entities responsible for excessive emissions.
• Two new long-term auto-GC monitors (these monitors perform
continuous, near-real-time VOC monitoring) will be installed at DISH and Eagle Mountain Lake to get a better understanding of long-term ambient air conditions, and to help assess the effectiveness of the TCEQ's actions, and to provide information on how to focus future efforts.
• The TCEQ will continue reconnaissance investigations in the
area, using both ground and air-based monitoring assets, and conduct a special emissions inventory of sources including an actual gas analysis from each site.
• The TCEQ will investigate sources for proper permit
authorizations and require testing of sites with continued excessive emissions.
• The TCEQ has undertaken a review of permitting rules that apply
to oil and gas operations. The review will ensure that authorizations and permits are enforceable, and protective of public health, and that they properly regulate all operations located at an oil and gas site.
• The TCEQ will continue to provide compliance assistance to small
operators, focused initially on condensate producers.
BACKGROUND OF SURVEY:
The TCEQ’s mobile monitoring organization conducted three surveys, one each in August, October, and November 2009 in Denton, Wise, Parker, Hood, Johnson and Tarrant counties. The surveys measured air emissions around a wide variety of natural gas and natural gas-related production facilities. Monitoring staff made every effort to collect emissions measurements downwind of the sources, moving around to stay in the plume where emissions would be most concentrated. Monitoring staff used hand-held VOC monitors, gas chromatographic monitors mounted in specialized TCEQ vehicles, infrared cameras that detect VOC emissions invisible to the naked eye; and instantaneous VOC canisters that take samples that are later analyzed in the laboratory with high levels of accuracy.
Another survey is scheduled for the same area during the spring.
MORE INFORMATION AND DATA:
More information and data from this study, including the toxicology department memo and the monitoring report, are posted on the TCEQ's Barnett Shale Web site at http://www.tceq.state.tx.us/goto/barnettshale
In December, the TCEQ conducted an air monitoring survey around 126 gas production sites in the city of Fort Worth. This monitoring survey found no levels of concern for any compounds. This survey was unrelated to the larger Barnett Shale study.
Full report (PDF file): http://www.tceq.state.tx.us/assets/publ ... tShale.pdf