Sandoval Zinc Company operated a smelter for 85 years. Zinc smelting is the process for converting zinc-bearing ores into pure zinc. The company closed in 1985 and filed bankruptcy in 1986. Air emissions from the plant included metals and wind-blown ash. Large amounts of the cinder/slag from smelting were used in constructing and surfacing secondary roads and for fill material on the property. The cinder/slag material not used by the plant was offered to the public and the Village of Sandoval to construct roads, driveways, sidewalks and parking lots.