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Air toxic assessment for short-term ambient air pilot study at private house in Battlement Mesa near oil and gas drilling site




Alhaji, Hussain, author
Reynolds, Stephen J., advisor
Brazile, William Joseph, committee member
Kreidenweis, Sonia M., committee member

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This pilot study evaluated the ambient air concentrations in Battlement Mesa, Colorado at private house near a well pad, for the four-day period of February 7 through February 10 of 2011. The natural gas site was operating in the production phase of oil and gas development process, and there were 12 wells commercial line. The overlying purpose of the study was to provide preliminary evaluation of air quality characteristics within Battlement Mesa with particular attention to Speciated Non-Methane Organic Compounds/Volatile Organic Compounds (SNMOC/VOCs), fine particulate matter (PM2.5) and total volatile organic compounds (TVOC's). SNMOCs including benzene, toluene, ethylbenezene, and xylene (BTEX) compounds were collected and analyzed using a modified EPA Organic Compendium Method TO-12 over a 22-hour period using Summa-polished stainless steel canisters. PM2.5 levels were measured using a directing reading photometer, a Personal Data RAM (pDR-1200) for 24-hour sampling period. Total VOCs, were measured in real-time using a Rae Systems PPB Rae 3000 photo ionization detector (PID). To measure the meteorological data, a portable weather station was deployed at the fire station site (FR) during the sampling period (about half mile from the sampling location). Sampling was performed at two locations around the private house, and background samples were collected at the FR for each parameter. The large percentage of detection (high prevalence i.e. ~95%) in samples from all sites appears to indicate that local VOCs sources do have impacts on air pollution levels. Compounds that were detected in the highest concentrations were light alkanes (i.e. ethane, propane) and the BTEX group (benzene, toluene, ethylbenzene and xylenes). The BTEX group, benzene in particular, recorded a potential health risk compared to the Risk Based Concentration (RBC) developed by the Environmental Protection Agency (EPA). In general, the SNMOCs/VOCs levels detected were low for all samples. TVOCs levels were also low and are consistent with the BTEX group where the background site recoded higher levels than the sampling sites (Upstream "UP" and Downstream "DN" sites). No exceedances of Federal National Ambient Air Quality Standards were recorded for PM2.5. In addition, PM2.5 concentrations were generally highest in the UP site which is close to the well pad. Comparisons of PM2.5 data to data from other studies in Garfield County show that PM2.5 concentrations in Battlement Mesa (oil and gas development area) are similar to or higher than the Rifle area (urban area) Meteorological monitoring was performed on a continuous basis with one-hour averages being generated. Wind speed and precipitation (snow) are the most pronounced meteorological parameters that are correlated with VOCs and PM2.5 levels. Overall for the study, pollutant levels were found to be generally very low as compared to the standards and suggested guidelines. In some locations, it is likely that more elevated pollutant levels are the result of local or individual sources. BTEX emissions sources should be evaluated more thoroughly and benzene in particular since elevated levels were observed. Given that benzene recorded a potential health hazard in the area (exceeded lower level for cancer risk), it is recommended that a comprehensive air study that measures VOCs at different seasons and at other well-development processes be conducted. The background site (FR) is affected by several emission sources. Therefore, it is recommended to relocate the background site to have a better representative background. A direct reading photometer method using the Personal Data RAM (pDR1200) is not the best method to collect the particulates during the winter season due to instrument related temperature bias. Therefore, an alternative method to measure the particulate matter is advised.


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