Hydrogeology and water-quality conditions at the City of Olathe Landfill, east-central Kansas, 1990-93

Water quality at the City of Olathe Landfill in east-central Kansas was examined in relation to hydrogeologic conditions to help determine the effects of the landfill on shallow ground water. This study focused on the Wyandotte and Plattsburg Limestones underlying the landfill. The Wyandotte Limestone underlies the entire landfill, whereas the overlying Plattsburg Limestone crops out within the landffll boundaries. Little Cedar Creek, an unnamed tributary, and a pond are located in the landfill. Water samples from seven monitoring wells and five surface-water sites in the vicinity of the City of Olathe Landfill were collected for analysis of inorganic and organic constituents. The inorganic constituents in the ground water that are most affected in the vicinity of the landfill are calcium, magnesium, sodium, bicarbonate, ammonia, barium, iron, and manganese. The dissolved- organic-carbon concentration at a seep flowing from the Plattsburg Limestone was 1,400 milligrams per liter, indicating that the landfill is affecting the water quality near the seep. Benzene was detected in all of the water samples, and the largest concentration was in a sample collected upgradient of the landfill. The benzene concentration exceeded the U.S. Environmental Protection Agency's Maximum Contaminant Level (0.005 milligram per liter) for drinking-water supplies. Six of the eight specific organic compounds detected were found in a water sample collected from the Plattsburg Limestone immediately downgradient of the landfill. No organic compoands, except benzene, were detected in samples collected from the Wyandotte Limestone downgradient of the landfill.