W

Natural and Anthropogenic Processes Affecting Domestic Groundwater Quality within the Northwestern Appalachian Basin

“…Cluster 3 samples exhibiting higher proportions of Cl (>15%) could be better approximated by modifying model 3 to account for mixing with local basin brine compositions (model 4, Figure B), which is also consistent with the observed higher helium concentrations, higher 4 He/ 20 Ne, and lower average ratios of 3 He/ 4 He. Shallow basin brines are known to be present throughout the Appalachian Basin, primarily associated with valley centers, where depth to saline water is shallow and stress-relief fractures have enhanced upward migration of brines. ,− ,,,, Ratios of Cl to Br for these high-Cl samples were indicative of mixing with basin brines, as opposed to domestic sewage or road salting sources as in C1 and C2 (Figure S8). While brines released from UOG and COG operations can exhibit similar Cl/Br ratios, no significant correlation with proximity to UOG, COG, or coal mining could be identified in the present study, providing little evidence for an anthropogenic source of salinity in C3. , Additionally, no significant associations between brine indicators (Cl, Br, F, Ba, and Li) and the distance to structural features (major synclines and anticlines) were observed in this study, contrary to earlier observations in northern West Virginia …”

“…Shallow basin brines are known to be present throughout the Appalachian Basin, primarily associated with valley centers, where depth to saline water is shallow and stress-relief fractures have enhanced upward migration of brines. 13 , 18 − 20 , 22 , 28 , 29 , 58 Ratios of Cl to Br for these high-Cl samples were indicative of mixing with basin brines, as opposed to domestic sewage or road salting sources as in C1 and C2 ( Figure S8 ). While brines released from UOG and COG operations can exhibit similar Cl/Br ratios, no significant correlation with proximity to UOG, COG, or coal mining could be identified in the present study, providing little evidence for an anthropogenic source of salinity in C3.…”

“…Our results reveal that valley regions in the western NAB serve as discharge areas for long-residence-time groundwaters in which rock–water interactions and ion exchange have shaped groundwater quality and major ion chemistry. Mixing with shallow basin brines also occurs in valley regions, as shown in other parts of the Appalachian Basin, ,− ,,,, though not all geochemically evolved groundwaters observed in valley regions exhibit elevated salinity.…”

“…Extensive stress-relief fracturing beneath valleys provides pathways for faster groundwater flow. − Domestic-well yields in valley settings generally range from (3.1 × 10 –4 )–(3.8 × 10 –4 ) m 3 /s, whereas yields in upland areas vary between 1.2 × 10 –4 and 1.9 × 10 –4 m 3 /s . When present, unconsolidated glacial and alluvial aquifers of quaternary-age and abandoned coal mines serve as additional sources of groundwater and frequently supply the highest flow rates ((6.3 × 10 –4 )–(6.3 × 10 –3 ) m 3 /s), though their lateral extent is limited. ,− Self-reported domestic-well depths in this study range from <15 to >150 m, with 46% falling between 15 and 50 m. Methane-rich basin brines have been reported within the study area and across the Appalachian region, often associated with proximity to valley centers and structural features. ,− ,,,, Several gentle anticlinal and synclinal folds are present in the region, generally trending north-south (Figure ). …”

“… 41 , 54 − 57 Self-reported domestic-well depths in this study range from <15 to >150 m, with 46% falling between 15 and 50 m. Methane-rich basin brines have been reported within the study area and across the Appalachian region, often associated with proximity to valley centers and structural features. 13 , 18 − 20 , 22 , 28 , 29 , 58 Several gentle anticlinal and synclinal folds are present in the region, generally trending north-south ( Figure 1 ). 59 …”