The process of primary zinc smelting occurred in Palmerton, Pennsylvania between 1898 and 1980. During the more than 80 years of smelter operation, it is estimated that airborne emissions averaged approximately 47 tons of cadmium per year, 95 tons of lead per year, 3,575 tons of zinc per year, and between 1,400 to 3,600 pounds of sulfur dioxide per hour. The sulfur dioxide combined with fog and/or precipitation to form sulfuric acid which contributed to the deforestation of Blue Mountain and Stoney Ridge, as well as sections of Palmerton and Aquashicola. The heavy metals zinc, cadmium, and lead accumulated in the soils to concentrations which are phytotoxic, inhibiting the re-establishment of vegetation in many areas.
Heavy metal concentrations in soil on Blue Mountain have been recorded as high as 1,300 ppm cadmium, 6,474 ppm lead, and 32,085 ppm zinc. During more than 70 years of operating the East Smelter facility the New Jersey Zinc Company dumped approximately 33 million tons of residue at the site creating a cinder bank 500 to 1,000 fee wide, 200 feet tall, and 2 1/2 miles in length. Soil erosion from the Blue Mountain and runoff from the cinder bank have contaminated the Aquashicola Creek and Lehigh River.
Elevated levels of lead and cadmium were detected in the blood and hair of children from Palmerton. Horses and cattle in the area developed substantiated cases of illness and fatigue from high concentrations of lead and cadmium. Consequently, the U.S. EPA proposed the site for placement on the Superfund National Priorities List (NPL) on December 1, 1982. The U.S. EPA Palmerton Zinc Pile fact sheet identifies the final NPL date as September 1, 1983. Although primary zinc smelting was discontinued in Palmerton in 1980, other metal refining processes, including the refining of Electric Arc Furnace (EAF) dust has continued.