Recent studies demonstrated that thermogenic hydrocarbon gases are found at higher concentrations in shallow groundwater in close proximity to hydraulically fractured shale gas wells, and that the source of the gas is likely from faulty well casings. However, it is unclear if there is significant transport of larger (e.g., &gt; 4 C atoms) organic chemicals into groundwater near hydraulic fracturing activities. Here, 60 shallow groundwater samples from private wells in Northeastern Pennsylvania were analyzed for volatile organic compounds (VOCs) and gasoline range organic compounds (GRO), and 37 were analyzed for VOCs, GRO, and diesel range organic compounds (DRO). GRO did not correlate with distance to the nearest shale gas well, active zones (defined as sample locations within a 1 km radius of a shale gas well), density of wells in active zones, or any inorganic markers indicative of Marcellus brine character (e.g., high Cl<sup>-</sup> and Br<sup>-</sup>). DRO was not correlated with the inorganic chemical characteristics of Marcellus Shale brine (p = 0.60). However, in contrast to GRO, DRO did spatially correlate with distance to the nearest shale gas well (p &lt; 0.05) and active zones (p &lt; 0.05), and correlated with the density of shale gas wells in active zones (p &lt; 0.05). Sensitivity analysis indicated that these significant correlations persisted even when anomalously high DRO values (e.g., &gt; 100 ppb, n=2) in close proximity to shale gas wells were eliminated. The source of higher DRO in the shallow groundwater is being investigated using comprehensive two-dimensional gas chromatography.

Trace levels of diesel range organic compounds in shallow groundwater wells in northeastern Pennsylvania elevated near Marcellus shale gas wells

249th National Meeting (2015)

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