The 200-acre Arkansas City Dump site, in Arkansas City, Cowley County, Kansas, abuts a levee to the west and south which separates the site from the Arkansas River. Between 1916 and 1927, an oil refinery was operated onsite processing between 6,000 and 12,000 barrels of oil per day. After an explosion destroyed the refinery in 1927, the site was used as a municipal landfill. The refinery treated petroleum fractions with sulfuric acid to improve color and to remove asphaltenes, paraffins, and resinous substances generating acid sludge waste in the process. The sludge waste was disposed of onsite in earthen pits in the north waste area and remediation of the area was addressed in a 1988 Record of Decision (ROD), as operable unit one. The second and final operable unit addressed the remainder of the site, which contains subsurface petroleum contaminants trapped in the soil below the water table as a result of petroleum spills. Results from remedial investigations revealed only low levels of soil and ground water contamination due to onsite disposal of municipal wastes. These contaminants, however, are not being released in significant concentrations and do not pose a significant threat to human health or the environment.