The former Asarco smelter site, also known as the Tacoma smelter, was one of the first Superfund sites in the nation. Under EPA's oversight, Asarco sampled soil at 3,570 properties in Ruston and North Tacoma and replaced soil at 2,436 of those properties. The EPA's work focused on the areas closest to the former smelter. Properties qualified for soil work when they had arsenic levels over 230 parts per million.
If you live in the study area (see map), it is very likely that your property was sampled by the EPA. To find soil sampling information for your yard, go to our public database.
Managing risk and addressing soil contamination
Today, we continue the work on yards that was started by the EPA over 20 years ago. We work area by area to replace soil containing high levels of lead and arsenic. In some cases, we go back to places that did not qualify under the EPA’s program to replace soil in those yards.
The Interim Action Plan is Ecology's plan to address contamination in the overall Tacoma Smelter Plume (over 1,000 square miles). In June 2012, after incorporating public comments, Ecology issued the final Interim Action Plan.
The Final Program Design and Implementation plan is Ecology's plan to address contamination in the
Yard Program Service area. This is the area closest to the former smelter. The main objective of the Yard Program is to reduce human health risk from arsenic and lead in soils. We meet this objective through soil sampling, soil replacement, and outreach.
In 2006, Ecology also started the
Soil Safety Program to assess and sample soil at schools and licensed childcare facilities within the Tacoma Smelter Plume. In 2010, Ecology amended the design to include parks, camps, and public multi-family housing play areas.
Studying contamination
The start of cleanup raised interest in cleaning up arsenic and lead contamination beyond EPA’s cleanup area. Early studies from before 1987 looked at soil in yards, play fields, forests, and other areas. However, many of the studies had few samples and only covered small areas. In 1999, Ecology began working with local health departments on a series of studies to find the full extent of smelter contamination.
These studies helped define the Tacoma smelter plume, linked Asarco to the contamination, and explored using ferns to clean up soils.
Sources of contamination
Ecology evaluated the possible source or sources of the contamination and compiled this information in the Credible Evidence Report below.
Fern Phytoremediation Study
Some plants readily take up arsenic and other heavy metals from the soil. The Chinese brake fern (Pteris vittata) can take up arsenic into its fronds at a very high rate. From 2005 to 2007, Ecology did a study to see if the Chinese brake fern could clean up Tacoma Smelter Plume contamination.
Findings: Ferns are not a good cleanup tool for the Tacoma smelter plume; see the reports below for why.