SPATIAL ANALYSIS OF STABLE ISOTOPIC VARIATIONS IN SURFACE WATERS OF AN AREA OF ACCELERATING MARCELLUS SHALE DEVELOPMENT IN NORTH-CENTRAL WEST VIRGINIA

The Monongahela River basin in West Virginia is undergoing intense development of natural gas reserves found in the Marcellus Shale. There are concerns that hydraulic fracturing, a technique to achieve economic gas production from the Marcellus Shale, presents several possible hazards to surface waters and groundwaters. During hydraulic fracturing a mix of water, sand and chemicals is injected thousands of feet underground under high pressure, breaking up shale formations to release trapped gas. The fluids that are injected in to the target formation are returned to the surface as flowback water. The flowback water can potentially contain toxic chemicals and highly saline brines. Leaky storage ponds, accidents involving transportation of water, and improper disposal of flowback water has potential to contaminate surface waters in areas of shale gas development. The focus of this study is to document stable isotopic and geochemical variations in surface waters within the Monongahela River basin. Fifty sites are being sampled in the basin and range in size from 10.4 mi² to 39.8 mi². The sampling sites were chosen from the extensive USGS database and are subdivided in to 4 categories representing different stages of Marcellus shale gas development in the basin. The 4 categories are low production, high production, near high production, and underlain by Marcellus Formation greater than 50 feet thick. At each sampling site, a width and depth-integrated sample is collected and analyzed for major-ion chemistry, trace elements, isotopic composition of water (δ¹⁸O_H2O, δ²H_H2O), DIC (δ¹³C_DIC), dissolved sulfate (δ³⁴S_SO4, δ¹⁸O_SO4), and field parameters of temperature, pH, conductivity, dissolved oxygen, turbidity, and oxidation reduction potential. All samples are being collected at base flow conditions to ensure all contributions to surface water are from ground water. Statistical and spatial analysis at base flow is used to establish and compare geochemical and isotopic variations in surface water of the 4 categories of Marcellus Shale gas development in the Monongahela River basin. Establishing these geochemical and isotopic conditions at baseflow will allow for understanding of potential impacts to water quality as this area undergoes rapid expansion of shale gas development.