The United States Environmental Protection Agency (EPA) estimates that 8 to 12% of U.S. homes have radon concentrations that equal or exceed 4 picocuries per liter (pCi/l). A statewide screening of Kentucky by EPA resulted in an average residential radon concentration of 2.8 pCi/l with 17% of the homes at or above 4 pCi/l. EPA requires routine monitoring and maintenance or worker health records in mines and caves having radon daughter concentrations at or above 0.30 working levels (WL). Bowling Green is a city located in a karst region of south central Kentucky. Residents of Bowling Green have been subjected to various environmental hazards that are closely linked with the landscape. Of particular concern has been the recurring problem of chemical fumes rising from contaminated caves and collecting in buildings. The author has recorded radon daughter concentrations in excess of 5 WLs in caves beneath Bowling Green. A preliminary screening of residential radon concentrations in Bowling Green resulted in an average concentration of 25.8 pCi/l. Two of the test results were above 100 pCi/l and were recorded in homes that were known to have a history of fume problems. These results spurred this thesis which addresses the magnitude of residential radon contamination in Bowling Green and its association with the karst landscape. The investigation involved radon daughter testing in Bowling Green caves and residential radon testing. A total of 84 measurements were conducted in order to establish a working average residential radon concentration for the city. Twelve other tests were performed in buildings known to have a history of chemical fume problems. The resulting average residential radon concentration was 9.06 pCi/l. First floor measurements averaged 4.73 pCi/l, and basement measurements averaged 22.92 pCi/l. The overall average for buildings with a history of fume problems was 35.15 pCi/l with first floors and basements averaging 29.75 and 57.40 pCi/l respectively. Forty-six percent of the homes comprising the sample population equaled or exceeded 4 pCi/l. The results of the investigation indicate that: Bowling Green Caves sometime have radon daughter concentrations far in excess of 0.30 WL. The average residential radon concentration for Bowling Green exceeds the average for Kentucky obtained by EPA. The percentage of houses that have radon concentrations at or above 4 pCi/l for the study area exceeds the estimated national average of 8 to 12% and the statewide average. The author suggests that insufficient data was collected to determine whether radon concentrations in Bowling Green homes with a history of chemical fume problems are higher than for the city as a whole.

The Lost River Groundwater Drainage Basin in Warren County, Kentucky, is a karst drainage system encompassing 55 square miles (143 square kilometers) developed within the Mississippian St. Louis and Ste. Genevieve Limestones. Near the contact between these two formations are two bedded chert units, the Lost River Chert Bed (Elrod, 1899) within the Ste. Genevieve and the Corydon Chert Member (Woodson, 1983) of the St. Louis, which appear to be perching layers to shallow karst groundwater flow. Groundwater may be seen flowing on top of these beds in various cave streams and at swallets and springs throughout the basin. In order to compare the vertical positions of these layers to shallow karst groundwater flow, geologic structure maps of the Lost River Chert Bed and the Corydon Chert Member were prepared for the basin, along with a contour map of the water table (at or near which shallow karst groundwater flow is assumed to take place) over the same area. These surfaces were digitized, then contoured and compared using SURFACE II and DISSPLA computer graphics systems. Correlation was accepted for points where the water table is either 20 feet (6.1 meters above or below the top of the two chert layers. The water table (at baseflow conditions) was found to correlate with the Lost River Chert Bed over 42.6% of the basin, as well as 40.7% for the Corydon Member. Shallow karst groundwater flow is found to correlated with bedded chert layers over 83.3% of the study area, and therefore it is concluded that chert layers have a dominant effect on the vertical position of groundwater flow within the Lost River Groundwater Drainage Basin.

Monthly water samples collected from four sites in the Lost River Groundwater Basin, a shallow karst aquifer in the Bowling Green-Warren County area of Kentucky, represented samples from sites receiving conduit and diffuse flow. All sites were severely contaminated with bacteria, and on some occasions the surface water criteria for some heavy metals were exceeded. Of the total 334 bacterial colonies identified 92.1% were verified as Escherichia coli by the API20E system. Acinetobacter calcoaceticus var. anitratum accounted for 2.10% of colonies; Citrobacter freundii for 0.30% Klebsiella pneumoniae for 0.90%; Klebsiella oxytoca, 0.90%; Citrobacter amalonaticus 0.30%; Enterobacter cloacae, 1.20%; Enterobacter sakazakii 0.60% and unidentifiable isolates 1.2%. A calcoaceticus var. anitratum had morphologically distinct tiny blue colonies on Levine Eosin Methylene Blue agar (LEMB). Fecal coliform (FC) and fecal streptococcus (FS) densities were variable and FC densities exceeded surface water criteria (SWC) on numerous occasions. Geometric means for FC colonies also exceeded SWC. The FC/FS ratios indicated both farmland and human pollution. The most frequently identified E. coli had an API profile No. 5144572 and the second most frequent had an API profile No. 5044552. The most frequently (76.92%) identified streptococcal species was Streptococcus durans. The S. durans that was most frequent (33.85%) of the Streptococcal isolates identified had an API profile No. of 5200441. All C. perfringens isolated gave a positive Reverse Camp Test. The bacterial densities at all sites followed the pattern of the respective hydrographs. The analysis of heavy metals indicated that varying concentrations of different metals were present at the sites studied. The metal found in the highest concentration at all four sites was iron. The concentrations of iron found were virtually always (>94% of the time) in violation of surface water criteria (SWC). Copper and zinc concentration were always less than that specified by SWC while silver, cadmium and chromium had concentrations which exceeded SWC on occasions.

Karst terrains, such as the Lost River Karst Ground-Water Basin, are extremely vulnerable to ground-water contamination. Seven physical factors: depth to water, recharge, aquifer media, soil media, topography, impact of the vadose zone, and hydraulic conductivity, are evaluated using the DRASTIC system to determine the ground-water pollution potential of the study area. A numerical value is calculated for each of the seven factors, and a map layer for each factor is produced. These layers are then “added” together to produce a DRASTIC ground-water pollution potential map. The effectiveness of each factor in evaluating the pollution potential of karst terrain is discussed. It was determined that small scale hydrogeologic features unique to karst areas provide significant influences on contaminant transport that are not addressed by the DRASTIC methodology. Therefore, it is recommended that modifications to the DRASTIC system be made by the users of the DRASTIC system when evaluating the pollution potential of a karst terrain.

Hydrogeologic investigations were conducted on the drainage systems of an area of the Pennyroyal sinkhole plain of south central Kentucky. The degree of karstification of five area streams was studied to develop an understanding of the evolution of drainage as the landscape changes from a sandstone caprock plateau to a limestone sinkhole plain. The Chester Upland, capped by the Big Clifty Sandstone, possesses predominantly surface drainage and the Pennyroyal Plain, formed on Mississippian limestones, possesses considerable subsurface drainage. As the Chester Upland Escarpment retreats and surface streams are onto the limestones, the streams evolve to become subsurface streams. The five streams observed in the study (all flowing on limestones) demonstrated less karst development close to the Chester Escarpment and more karst development with increasing distance from the escarpment. Sediments derived from the escarpment and plateau blanket the stream beds thus perching the streams and preventing chemically aggressive water from forming karst solution features in the limestones. The streams farther away from the escarpment are removed from the sediment source and are therefore able to downcut into the limestone and invade the subsurface to become cave streams. Lithologic investigation of limestones exposed in stream beds revealed that minor resistant units can act to diminish downcutting and maintain short sections of surface flow. The stream investigated was not flowing on a perching layer, but instead was held on the surface by a stratigraphic control (spillover layer) that prevented subterranean stream invasion. Dye traces conducted on groundwater flow in the sinkhole plain revealed that the area drainage pattern is changing as surface streams invade the subsurface and that integration between drainage basins is taking place. Stream piracy and stream diversion are occurring in the subsurface causing alteration of the existing topographic drainage divides that developed before the surface streams invaded the subsurface. A general model is presented which shows the evolution of surface drainage to subsurface drainage, as the Chester Escarpment continues its northwestward retreat.