An industry-funded assessment of ambient air quality in the area of Barnett Shale natural gas operations in Fort Worth and Arlington (TX) City Council District 2 found no harmful levels of benzene or other compounds, according to the Barnett Shale Energy Education Council (BSEEC).

BSEEC sponsored the study, which was conducted by Titan Engineering Inc. Titan identified sites with the highest production of natural gas and liquids based upon the most recent natural gas production data available at the time from natural gas operators and the Railroad Commission of Texas. In two instances, sites with the second-highest projected benzene emissions levels were selected due to their proximity to homes and schools.

"Prior to the implementation of this study, widespread concern existed regarding human exposure to benzene and other pollutants being emitted from natural gas sites," the study report said. "These concerns were the primary driver behind this study, and consequently the air sampling plan was designed around identifying and sampling the natural gas sites which were projected to have the highest benzene emission rates."

Ten natural gas sites were tested, including two compressor stations recommended by the city of Fort Worth and eight producing well sites, including both condensate-producing and dry natural gas wells. While previous air monitoring studies in Fort Worth have evaluated natural gas sites at random, Titan tested completed well sites within the cities of Fort Worth and Arlington District 2, which were projected to have the highest benzene emissions.

"Because we tested sites projected to have the highest benzene emission rates and found no site-related concentrations in excess of the study's health-based criteria, Titan concludes that harmful levels of benzene and other compounds are not being emitted from natural gas sites in the study area," said Titan's Doug Canter, who led the study.

Titan utilized best practices, analytical methods and standards used by the U.S. Environmental Protection Agency and the American Society for Testing and Materials, according to BSEEC.

The study compare the detectable compound concentrations with the study's health-based criteria established by the Texas Commission on Environmental Quality (TCEQ) and the U.S. Department of Health. Titan also investigated any other possible contributing sources to the readings. The firm was able to differentiate between the natural gas site contributions to detectable compound concentrations and contributions from other sources, based on comparison of upwind and downwind sampling in the vicinity of the natural gas sites, BSEEC said.

The full report can be found at www.bseec.org.

Earlier this year the Texas Department of State Health Services tested 28 residents of DISH, TX -- where Barnett Shale gas activities are thought by some to have polluted the air -- for exposure to volatile organic compounds. The residents tested were not found to have unusual levels of the compounds (see Daily GPI, May 14).

In January TCEQ said a Barnett Shale air quality study said most readings were "well below" acceptable exposure limits. The study followed complaints by residents who claimed that their air was fouled and their water was contaminated by gas activities (see Daily GPI, Dec. 18, 2009; Nov. 25, 2009). TCEQ scientists analyzed more than 100 volatile organic compounds but mainly focused on benzene.

TCEQ is in the process of compiling an inventory of gas field equipment in the Barnett Shale that could be responsible for emissions. The data will be used for modeling emissions control measures, the agency said (see Daily GPI, May 3).

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