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ABSTRACT
A pilot study was conducted in application of the U.S. Environmental Protection Agency (EPA) Methods 325A/B variant for monitoring volatile organic compounds (VOCs) near two oil and natural gas (ONG) production well pads in the Texas Barnett Shale formation and Colorado Denver–Julesburg Basin (DJB), along with a traffic-dominated site in downtown Denver, CO. As indicated in the EPA method, VOC concentrations were measured for 14-day sampling periods using passive-diffusive tube samplers with Carbopack X sorbent at fenceline perimeter and other locations. VOCs were significantly higher at the DJB well pad versus the Barnett well pad and were likely due to higher production levels at the DJB well pad during the study. Benzene and toluene were significantly higher at the DJB well pad versus downtown Denver. Except for perchloroethylene, VOCs measured at passive sampler locations (PSs) along the perimeter of the Barnett well pad were significantly higher than PSs farther away. At the DJB well pad, most VOC concentrations, except perchloroethylene, were significantly higher prior to operational changes than after these changes were made. Though limited, the results suggest passive samplers are precise (duplicate precision usually ≤10%) and that they can be useful to assess spatial gradients and operational conditions at well pad locations over time-integrated periods.
Implications: Recently enacted EPA Methods 325A/B use passive-diffusive tube samplers to measure benzene at multiple fenceline locations at petrochemical refineries. This pilot study presents initial data demonstrating the utility of Methods 325A/B for monitoring at ONG facilities. Measurements revealed elevated concentrations reflective of production levels and spatial gradients of VOCs relative to source proximity at the Barnett well pad, as well as operational changes at the DJB well pad. Though limited, these findings indicate that Methods 325A/B can be useful in application to characterize VOCs at well pad boundaries.
Acknowledgments
The authors thank John Turlington, Patti Tyler, Michael Morton, Jason Weinstein, and Ray Merrill of EPA and Laura VanEnwyck and Dave Dayton of Eastern Research Group for assistance. They also thank the Colorado Department of Public Health and the Environment, two industry collaborators, and the U.S. Forest Service for providing site access.
Disclaimer
The U.S. Environmental Protection Agency through its Office of Research and Development funded and managed the research described here under contracts EP-D-10-070 and EP-D-11-006 to Alion Science and Technology and Eastern Research Group, respectively. The paper has been subjected to agency review and approved for publication. The views expressed in this paper are those of the authors and do not necessarily represent the views or policies of the U.S. Environmental Protection Agency. Mention of trade names or commercial products does not constitute an endorsement or recommendation for use.
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Notes on contributors
Adam P. Eisele
Adam P. Eisele is an Environmental Engineer at U.S. Environmental Protection Agency (EPA) Region 8.
Shaibal Mukerjee
Shaibal Mukerjee and Donald A. Whitaker are Research Physical Scientists and Karen D. Oliver and Maribel Colon are Research Chemists, all at EPA’s Office of Research & Development (ORD), National Exposure Research Laboratory (NERL).
Luther A. Smith
Luther A. Smith is a Senior Statistician and Casson Stallings is a data analyst and environmental modeler with Alion Science & Technology.
Eben D. Thoma
Eben D. Thoma and Tai Wu are Physical Scientists with EPA/ORD’s National Risk Management Research Laboratory.
Donald A. Whitaker
Shaibal Mukerjee and Donald A. Whitaker are Research Physical Scientists and Karen D. Oliver and Maribel Colon are Research Chemists, all at EPA’s Office of Research & Development (ORD), National Exposure Research Laboratory (NERL).
Karen D. Oliver
Shaibal Mukerjee and Donald A. Whitaker are Research Physical Scientists and Karen D. Oliver and Maribel Colon are Research Chemists, all at EPA’s Office of Research & Development (ORD), National Exposure Research Laboratory (NERL).
Tai Wu
Eben D. Thoma and Tai Wu are Physical Scientists with EPA/ORD’s National Risk Management Research Laboratory.
Maribel Colon
Shaibal Mukerjee and Donald A. Whitaker are Research Physical Scientists and Karen D. Oliver and Maribel Colon are Research Chemists, all at EPA’s Office of Research & Development (ORD), National Exposure Research Laboratory (NERL).
Lillian Alston
Lillian Alston is a scientist working with EPA/ORD/NERL through the NCBA/SEE Program.
Tamira A. Cousett
Tamira A. Cousett is a Chemist currently with Jacobs Technology.
Michael C. Miller
Michael C. Miller is an Environmental Scientist and Donald M. Smith is a Physical Scientist at EPA Region 6.
Donald M. Smith
Michael C. Miller is an Environmental Scientist and Donald M. Smith is a Physical Scientist at EPA Region 6.
Casson Stallings
Luther A. Smith is a Senior Statistician and Casson Stallings is a data analyst and environmental modeler with Alion Science & Technology.