Background on the Tacoma Smelter Plume

The American Smelting and Refining Corporation (ASARCO) operated a copper smelter on the shores of Commencement Bay in Ruston, near Tacoma, Washington for almost 100 years. The facility began its life as a lead smelter in 1889, and was converted to a copper smelter in 1902. It was sold to ASARCO in 1905.

For decades, the company processed rock ore in a procedure known as smelting. ASARCO produced copper that is used in electronics, roofing, household products, coins, and biomedical and chemical applications, among other uses.

A byproduct of copper smelting is arsenic. The Ruston smelter was one of the only smelters in the world able to process ore containing a high percentage of arsenic. In fact, the Ruston smelter collected much of its arsenic and sold it for use in insecticides and building materials. Unfortunately, not all of the arsenic was collected for sale. Along with lead and other chemical byproducts of copper smelting, some of it was released out through the smokestack into the environment.

The smelter was known for its tall 562 foot smokestack, which sent pollutants up and away from the smelter into surrounding communities. While the smelter was permanently closed in 1986 and the stack demolished in 1993, the environmental damage was already complete. We now know that lead and arsenic pollution was carried by the wind over a wide expanse of King, Pierce, Thurston, and Kitsap counties.

When the lead and arsenic carried by the wind settled on the ground, it contaminated the soil.

The contamination of the area surrounding the smelter was so serious that in 1983 the United States Environmental Protection Agency included the smelter site, with its 23 acre peninsula built from slag, as part of a Superfund site called the Commencement Bay Superfund site.

Since 2000, Public Health - Seattle & King County and the Washington State Department of Ecology have partnered to investigate the nature and extent of the contamination in King County. Over 8,000 soil samples have been taken at more than 900 locations. More than half of the locations showed at least one soil sample with arsenic above the state clean up level of 20 parts-per-million, and about 18% showed lead above the state clean up level of 250 parts-per-million.

Where is most likely to have ASARCO contamination?

Since 1999, soil samples have been taken at different kinds of locations throughout King County, including forests and beaches, and schools, parks, and childcare centers. While soil contamination varies widely from city to city, neighborhood to neighborhood and even from one side of a property to another, there are some rules of thumb when it comes to ASARCO soil contamination in King County:

• The closer to the smelter the higher likelihood of contamination.
• Undisturbed or undeveloped properties, like old parks and forests, are more likely to be contaminated than newer properties because undeveloped properties were exposed to the air-borne pollution for the longest period of time.
• Studies show that that the highest ASARCO contamination typically occurs in the least developed areas, normally considered unspoiled or pristine.
• Properties that were developed after the smelter closed in the mid-1980s are the least likely have contamination because the contaminated soil was likely dug up, moved, added to or removed as part of the development process.
• South-facing to west-facing slopes are more likely to have soil contamination (depending on direction from smelter and prevailing wind direction).
• There is less lead compared to arsenic the farther from the smelter.
• The arsenic and lead tends to stay in the top 12 inches of soil.