title: Volatile organic compounds at two oil and natural gas production well pads in Colorado and Texas using passive samplers.
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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: a U.S. Environmental Protection Agency , Region 8, Denver , Colorado , USA.
authors.forename: Adam P
authors.initials: AP
authors.lastname: Eisele
authors.affiliation: b U.S. Environmental Protection Agency, Office of Research and Development, National Exposure Research Laboratory, Research Triangle Park , North Carolina , USA.
authors.forename: Shaibal
authors.initials: S
authors.lastname: Mukerjee
authors.affiliation: c Alion Science and Technology , Durham , North Carolina , USA.
authors.forename: Luther A
authors.initials: LA
authors.lastname: Smith
authors.affiliation: d U.S. Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory Research Triangle Park , North Carolina , USA.
authors.forename: Eben D
authors.initials: ED
authors.lastname: Thoma
authors.affiliation: b U.S. Environmental Protection Agency, Office of Research and Development, National Exposure Research Laboratory, Research Triangle Park , North Carolina , USA.
authors.forename: Donald A
authors.initials: DA
authors.lastname: Whitaker
authors.affiliation: b U.S. Environmental Protection Agency, Office of Research and Development, National Exposure Research Laboratory, Research Triangle Park , North Carolina , USA.
authors.forename: Karen D
authors.initials: KD
authors.lastname: Oliver
authors.affiliation: d U.S. Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory Research Triangle Park , North Carolina , USA.
authors.forename: Tai
authors.initials: T
authors.lastname: Wu
authors.affiliation: b U.S. Environmental Protection Agency, Office of Research and Development, National Exposure Research Laboratory, Research Triangle Park , North Carolina , USA.
authors.forename: Maribel
authors.initials: M
authors.lastname: Colon
authors.affiliation: b U.S. Environmental Protection Agency, Office of Research and Development, National Exposure Research Laboratory, Research Triangle Park , North Carolina , USA.|e Senior Environmental Employment Program, Research Triangle Park , North Carolina , USA.
authors.forename: Lillian
authors.initials: L
authors.lastname: Alston
authors.affiliation: c Alion Science and Technology , Durham , North Carolina , USA.
authors.forename: Tamira A
authors.initials: TA
authors.lastname: Cousett
authors.affiliation: f U.S. Environmental Protection Agency , Region 6, Dallas , Texas , USA.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Miller
authors.affiliation: f U.S. Environmental Protection Agency , Region 6, Dallas , Texas , USA.
authors.forename: Donald M
authors.initials: DM
authors.lastname: Smith
authors.affiliation: c Alion Science and Technology , Durham , North Carolina , USA.
authors.forename: Casson
authors.initials: C
authors.lastname: Stallings
mesh_terms: D003120:Colorado; D004784:Environmental Monitoring / Q000379:methods*; D061329:Oil and Gas Fields; D010865:Pilot Projects; D013781:Texas; D055549:Volatile Organic Compounds / Q000032:analysis*
chemical_list: D055549:Volatile Organic Compounds