The expanding use of horizontal drilling and hydraulic fracturing technology to produce oil and gas from tight rock formations has increased public concern about potential impacts on the environment, especially on shallow drinking water aquifers. In eastern Kentucky, horizontal drilling and hydraulic fracturing have been used to develop the Berea Sandstone and the Rogersville Shale. To assess baseline groundwater chemistry and evaluate methane detected in groundwater overlying the Berea and Rogersville plays, we sampled 51 water wells and analyzed the samples for concentrations of major cations and anions, metals, dissolved methane, and other light hydrocarbon gases. In addition, the stable carbon and hydrogen isotopic composition of methane (delta C-13-CH4 and delta H-2-CH4) was analyzed for samples with methane concentration exceeding 1 mg/L. Our study indicates that methane is a relatively common constituent in shallow groundwater in eastern Kentucky, where methane was detected in 78% of the sampled wells (40 of 51 wells) with 51% of wells (26 of 51 wells) exhibiting methane concentrations above 1 mg/L The delta C-13-CH4 and delta H-2-CH4 ranged from -84.0 parts per thousand to -58.3 parts per thousand and from -246.5 parts per thousand to -146.0 parts per thousand, respectively. Isotopic analysis indicated that dissolved methane was primarily microbial in origin formed through CO2 reduction pathway. Results from this study provide a first assessment of methane in the shallow aquifers in the Berea and Rogersville play areas and can be used as a reference to evaluate potential impacts of future horizontal drilling and hydraulic fracturing activities on groundwater quality in the region.

Clifton Cave in Woodford County, Kentucky, was known as the habitat for two unique cave-dwelling species only found living in the cave and associated nearby habitats. The cave was surveyed in 1964, but the only cave entrance was destroyed and sealed by road improvements in 1970. To determine whether these species are still present in the cave and to plan future conservation efforts, researchers need to regain access to the cave. A vertical access hole into the cave passage was proposed because the 1964 cave survey provided the general location of the cave passages. In order to determine potential drilling sites to locate cave passages, we conducted two electrical resistivity surveys. Orientation, length, electrode spacing, and location of the surveys were designed to detect three estimated cave passage targets. The survey results showed excellent correspondence between the high resistivity anomalies and all the estimated targets. Although survey results have not been confirmed by drilling, the excellent correspondence suggested the electrical resistivity method is a promising reconnaissance tool for locating caves at relatively shallow depths.

Shallow colluvial landslides are common in eastern Kentucky, as well as in the east-central Appalachian region. A geological, geotechnical, and geophysical investigation was carried out for a shallow colluvial landslide in Boyd County, KY. The purpose of this project was to assess the geologic conditions, extent, and behavior of a rainfall-triggered landslide in eastern Kentucky and to evaluate the use of electrical resistivity as a tool to characterize a shallow colluvial landslide. This study showed that 1) colluvial landslide movement is correlated to the rainfall and 2) inverted resistivity sections with distinct resistivity contrasts that correlated to landslide stratigraphy, depth of the failure surface, and groundwater regimes.

Cumberland Gap Tunnel was constructed under Cumberland Gap National Historical Park in 1996 to improve transportation on a segment of U.S. 25E, connecting Kentucky and Tennessee and restoring Cumberland Gap to its historical appearance. The concrete pavement in the tunnel started to subside in 2001. Ground penetrating radar surveys revealed voids in many areas of the limestone roadbed aggregate beneath the pavement. To investigate possible hydrogeologic processes that may have caused favorable conditions for voids to form in the aggregate, we studied geology, groundwater flow, and groundwater chemistry in the tunnel using a variety of methods, including bore drilling, packer test, dye tracing, groundwaterand surface-flow monitoring, waterchemistry modeling, and an aggregate dissolution experiment. The study revealed that the aggregate receives a large volume of groundwater from much of the bedrock invert, but the flow velocity is too slow to transport small particles out of the aggregate. Calcite saturation indices calculated from water-chemistry data suggest that the groundwater was capable of continuously dissolving calcite, the primary mineral in the limestone aggregate. Water samples taken during different flow conditions indicate that groundwater under high-flow conditions could dissolve calcite more quickly than groundwater under low-flow conditions. The dissolution experiment showed that all the limestone aggregate placed beneath the roadbed and in contact with groundwater lost mass; the highest mass loss was 3.4 percent during a 178-day period. The experiment also suggested that water with higher calcite-dissolving potential removed limestone mass quicker than water with low calcite-dissolving potential. We recommend that the limestone aggregate be replaced with noncarbonate aggregate, such as granite, to prevent dissolution and future road subsidence. Introduction On October 18, 1996, a segment of U.S. 25E from Middlesboro, Ky., to Harrogate, Tenn., was relocated into a newly constructed tunnel beneath Cumberland Mountain, to improve transportation efficiency and safety as well as help restore Cumberland Gap to its appearance when Daniel Boone brought the first settlers to Kentucky in the mid1Kentucky Geological Survey, University of Kentucky 2Kentucky Transportation Center, University of Kentucky