Pre-drilling water-quality data of groundwater prior to shale gas drilling in the Appalachian Basin: Analysis of the Chesapeake Energy Corporation dataset

Siegel, Donald I.; Smith, Bert J.; Perry, Elizabeth S.; Bothun, R.; Hollingsworth, Mark

doi:10.1016/j.apgeochem.2015.06.013

Cited by 47 publications

(81 citation statements)

References 24 publications

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“…These findings were not recognized by the original authors of the Cabot study and have not been reported in other studies. Compared to other studies (Molofsky et al, 2013; Siegel et al, 2015a; Siegel et al, 2015b; Warner et al, 2013), we recognized that for some GW samples, pre-drilling data can be used as post-drilling data as well due to nearby UGD. We also minimized the topographic effects by separating samples into four groups based on topography and distance.…”

Section: Discussionmentioning

confidence: 80%

“…Compared to the results in Siegel et al,2015a, which is an industry funded project, the percentage of Cabot samples exceeding EPA guideline levels is relatively low, possibly because a fraction of samples from the Cabot study were filtered to remove particles (before 2011), while the Chesapeake samples were unfiltered (Siegel et al, 2015a). For example, in the Cabot data set, about 0.9% of samples exceed EPA Pb guideline levels (0.015 mg/L), compared to 4.4% of the Chesapeake samples.…”

Section: Discussionmentioning

confidence: 85%

“…The level of Cl in the valley samples changes from insignificantly to significantly higher. Given that groundwater in valley settings can be affected by both shallow freshwater and underlying brine layers (Siegel et al, 2015a, Fig. 4), the increase of both freshwater Ca and SO4 and Cl (from underlying brine layers) in the valley near group indicates the increase of mixing of freshwater or deep brine in these valley samples..…”

Section: Discussionmentioning

confidence: 99%

“…The Na levels in valley samples with less UGD effect (i.e., the valley far group) was already high, thus depending on the mixing ratio, mixing of freshwater (low Na level) and saline water (high Na level) does not necessarily lead to an increase of Na levels. In addition, Na can be involved in an ion-exchange reaction (Siegel et al, 2015a), further complicating the Na results.…”

Section: Discussionmentioning

confidence: 99%

“…The impact of UGD on water quality has been hotly debated for the past several years (Gorody, 2012; Hildenbrand et al, 2016; Jackson et al, 2013a; Jackson et al, 2013b; Meng, 2015; Molofsky et al, 2013; Olmstead et al, 2013; Siegel et al, 2015a; Siegel et al, 2015b; U.S.EPA, 2015; Vidic et al, 2013; Warner et al, 2012). Multiple reasons contribute to uncertainty, including the lack of systematic surveys of water quality pre- and post- drilling/production, substantial dilution and slow transport over months to hundreds of years along flow paths from contaminated sites to private wells or public water supplies, and natural fluctuations of groundwater chemistry.…”

Section: Introductionmentioning

confidence: 99%

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Association of groundwater constituents with topography and distance to unconventional gas wells in NE Pennsylvania

Yan

Stute

Panettieri

et al. 2017

Science of The Total Environment

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Recently we reported an association of certain diseases with unconventional gas development (UGD). The purpose of this study is to examine UGD’s possible impacts on groundwater quality in northeastern Pennsylvania. In this study, we compared our groundwater data (Columbia 58 samples) with those published data from Cabot (1701 samples) and Duke University (150 samples). For each dataset, proportions of samples with elevated levels of dissolved constituents were compared among four groups, identified as upland far (i.e. ≥1km to the nearest UGD gas well), upland near (<1km), valley far (≥1 km), and valley near (< 1 km) groups. The Columbia data do not show statistically significant differences among the 4 groups, probably due to the limited number of samples. In Duke samples, Ca and CI levels are significantly higher in the valley near group than in the valley far group. In the Cabot dataset, methane, Na, and Mn levels are significantly higher in valley far samples than in upland far samples. In valley samples, Ca, Cl, SO4, and Fe are significantly higher in the near group (i.e. < 1 km) than in the far group. The association of these constituents in valley groundwater with distance is observed for the first time using a large industry dataset. The increase may be caused by enhanced mixing of shallow and deep groundwater in valley, possibly triggered by UGD process. If persistent, these changes indicate potential for further impact on groundwater quality. Therefore, there is an urgent need to conduct more studies to investigate effects of UGD on water quality and possible health outcomes.

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Section: Discussionmentioning

confidence: 80%

Section: Discussionmentioning

confidence: 85%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Association of groundwater constituents with topography and distance to unconventional gas wells in NE Pennsylvania

Yan

Stute

Panettieri

et al. 2017

Science of The Total Environment

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Methane occurrence is associated with sodium‐rich valley waters in domestic wells overlying the Marcellus shale in New York State

Christian

Lautz

Hoke

et al. 2016

Water Resources Research

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Prior work suggests spatial parameters (e.g., landscape position, distance to nearest gas well)can be used to estimate the amount of dissolved methane in domestic drinking water wells overlying the deep Marcellus Shale. New York (NY) provides an opportunity to investigate methane occurrence prior to expansion of high-volume hydraulic fracturing because unconventional gas production is currently banned in the state. We sampled domestic groundwater wells for methane in 2013 (n 5 137) across five counties of NY bordering Pennsylvania, and then resampled a subset of those wells in 2014 for methane concentrations and d 13 C-CH 4 and dD-CH 4 . The majority of waters from wells sampled (77%) had low concentrations of methane (<0.1 mg/L), and only 5% (n 5 7) had actionable levels of methane (>10 mg/L). Dissolved methane concentrations did not change as a function of proximity to existing vertical gas wells, nor other parameters indicating subsurface planes of weakness (i.e., faults or lineaments). Methane levels were significantly higher in wells closer to hydrography flow lines, and most strongly correlated to Na-HCO 3 water type. The distribution of methane between Ca-HCO 3 (n 5 76) and Na-HCO 3 (n 5 23) water types significantly differed (p < 0.01), with median methane concentrations of 0.002 and 0.78 mg/L, respectively. Combined classification of sampled waters based on the dominant water cation, well topographic position, and geologic unit of well completion effectively identified wells with a greater than 50% probability of having methane concentrations exceeding 1 mg/L. Such classification schemes may be useful as a screening tool to assess natural versus gas production-related sources of methane in domestic wells.

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Methane in Groundwater: Pathways

Martini

Osborn

McIntosh

2019

Encyclopedia of Water

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Groundwater can contain measurable quantities of methane associated with in situ processes of methanogenesis and desorption from geologic materials, and also from external migration from deeper gas‐bearing units. It may also contain “fugitive gas” due to leakage from exploration and production of hydrocarbons or from the microbial breakdown of organic contaminants introduced to the aquifer. More recently, natural gas production via high volume hydraulic fracturing of tight formations has been implicated as a route for both methane and other fluids to enter groundwater resources. While distinguishing the source of the gas is often critical, secondary processes such as mixing and aerobic and anaerobic oxidation make these identifications difficult. Important to these determinations is an understanding of the hydrology, geology, and history of development in the watershed, coupled with detailed geochemical and isotopic analysis.

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Pre-drilling water-quality data of groundwater prior to shale gas drilling in the Appalachian Basin: Analysis of the Chesapeake Energy Corporation dataset

Cited by 47 publications

References 24 publications

Association of groundwater constituents with topography and distance to unconventional gas wells in NE Pennsylvania

Association of groundwater constituents with topography and distance to unconventional gas wells in NE Pennsylvania

Methane occurrence is associated with sodium‐rich valley waters in domestic wells overlying the Marcellus shale in New York State

Methane in Groundwater: Pathways

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