The National Zinc Company (NZC) Facility is located on the western edge of the City of Bartlesville, Oklahoma. The NZC Facility began operations in 1907, primarily to recover metals such as zinc, cadmium, and lead for industrial materials. NZC used smelting and chemical processing to recover these metals. In addition to the NZC smelter, a vanadium smelter and two other zinc smelters have operated on the location that presently encompasses the current NZC Facility. These contaminants include arsenic, cadmium, copper, lead, mercury, selenium, silver, sulfuric acid and zinc. Historical metal processing operations by three horizontal retort zinc smelters commenced at this location in approximately 1907. Two of the smelters ceased operations in the 1920s. The remaining smelter was converted to an electrolytic zinc refinery in 1976 and is not currently operating. During the time the horizontal retorts were in operation, metals contained in the airborne emissions from the smelter(s) were deposited over much of the area of Bartlesville which lies west of the Caney River including residential, commercial, industrial, and ecological areas. Historical sources of metals at the NZC Facility included: ore delivered to the NZC Facility by railcar, dust from the transport and storage of ore and solid waste materials at the NZC Facility, metals emissions from roasting and smelting processes, airborne particulates from smelting and sintering processes, and various solid waste materials.