Geochemistry of Groundwater and Gases in the Vadose Zone in Selected Parts of Hays, Kansas

Abstract

The primary purpose of this study is to detect and describe chloride and nitrate in the groundwater, as well as volatile organic chemicals (VOCs) in the vadose zone, in selected parts of Hays, Kansas. The study also describes the subsurface behavior of these potential contaminants. Big Creek alluvial aquifer is an important source of groundwater for the city of Hays. Groundwater samples collected from different locations in the city were geochemically analyzed to determine the inorganic composition of the groundwater. Geochemical analysis suggests that groundwater in Hays is very hard and is of the Ca- HCO3 type. Computer calculations show that the water samples are saturated to oversaturated with respect to calcite. Therefore, calcite may control much of the water composition. The basic chemical characteristics of groundwater was studied using Stiff diagrams. Similar patterns of Stiff diagrams suggest that chloride and nitrate affect the groundwater quality. Animal or human waste sources could be an appreciable contributor to the total chloride and nitrate concentrations. Also, the Blue Hill Shale contributes to chloride, while leaky sewer lines could be another possible source for nitrate. Organic contaminants were detected in south Hays in the vadose zone using a soil-gas survey method conducted by Layne Geosciences, Inc. (LGI). Spills or casual dumping of petroleum products, leaking of underground storage tanks, and chemicals used in other cleaning processes are possible sources of the contamination.