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Dirt Alert! Tacoma Smelter Plume

Extended  Footprint

Tacoma Smelter Plume (Dirt Alert) Extended Footprint Study December 2004 Update

This update provides the latest results from the
Extended Footprint Study.

Introduction
Footprint Studies
Child-Use Area Studies
Resources: Simple Steps to Protect Your Health
Local Health Department Web Links

Introduction
Since 1999, the Department of Ecology (Ecology) and the King and Pierce County health departments have been studying soil pollution that came from the Asarco Smelter smokestack. The polluted smoke that came out of the smokestack traveled with the wind and settled onto soil in much of the southeastern Puget Sound Basin.
The agencies have studied:

• how far from the smelter the soils are polluted (Footprint Studies); and
• the amount of arsenic and lead in soils where children play (Child-Use Area Studies, King County Studies, and Pierce County Studies).

Extended Footprint Study

[The maps in this section are in Adobe Acrobat (.pdf) files, zoom in to better see map details*.]

The initial studies did not identify the polluted area’s boundary. To find out  how far the soil pollution extends, Ecology teamed up with the King, Kitsap,  Pierce and Thurston County health departments to conduct a final study - the Extended Footprint Study. Ecology provided grants to the four counties to conduct this work.

As of December 2004, sampling was completed in all four counties. The results appear consistent with the pattern of contamination seen in the initial studies. In general, the concentrations of arsenic and lead decrease with distance from the smelter and follow wind patterns. We believe we have sufficient information to determine the general boundary of the contamination.

The total area potentially impacted by smelter emissions appears to be 1000 square miles. The maximum concentrations at each sampling location are mapped for Arsenic and Lead.

Investigators collected soil samples from 51 undisturbed locations in northeastern Thurston County.  Nineteen locations had arsenic levels above the state cleanup level of 20 ppm, and one had lead levels above the state cleanup level of 250 ppm.

Among these soil samples, Thurston County has an area of interest with more soil contamination than anticipated.  In the highland area on top of the Nisqually Bluff, arsenic values topped out at 159 parts per million (ppm) and lead values at 1100 ppm.

The results seem to reflect the wind channeling down the Sound, hitting the bluff.  However, the arsenic and lead ratios do not fit the normal Tacoma Smelter Plume pattern.  There may be an additional source.  Thurston County Health is investigating further.

The Thurston County Health Department has been in contact with property owners in the area and will continue to work with them.  They are providing educational materials to area childcares for protection of kids and employees, in addition to advising all of Thurston County to follow public health protection measures such as washing dirty hands, and taking off shoes to avoid tracking in dirt.
Thurston County Maximum Arsenic
Thurston County Maximum Lead

Researchers collected soil samples throughout the county from the foothills west to the Puget Sound. Of the 165 new results reported by Public Health-Seattle & King County, 65 locations have arsenic above the state cleanup standard, and one location had lead above the standard. The highest arsenic and lead concentrations were 77 ppm and 311 respectively. The highest arsenic concentration found in previous studies was 460 ppm on south Vashon-Maury Island.
King County Maximum Arsenic
King County Maximum Lead

In Pierce County, soil samples were collected south and east of I-5, including areas near Roy and McKenna. Of the 84 new locations sampled, 18 had arsenic levels above the standard, and 12 had lead levels above the standard. The highest arsenic and lead concentrations were 352 ppm and 1940 ppm respectively. Previous studies found arsenic levels as high as 1050 ppm in Tacoma.
Pierce County Maximum Arsenic
Pierce County Maximum Lead

In Kitsap County, soil samples were collected along the Puget Sound coast line in eastern parts of the county. Of 53 locations sampled, 13 had arsenic levels above the standard, and no locations had lead above the standard. The highest arsenic and lead concentrations were 37 ppm and 198 ppm respectively.
Kitsap County Maximum Arsenic
Kitsap County Maximum Lead

We expect a report in spring 2005 that will summarize results from the initial and final studies, and includes a determination of the boundary of contamination.

Child-Use Area Studies
In addition to studying how far the pollution went, Ecology and the health departments in King and Pierce counties have studied the soils where children play – schools, parks, childcares. We are concerned about long-term exposure to the contaminated soil, especially for young children as they face the highest risk from soil contamination. Children like to play in the dirt. Very young children place dirty fingers and objects in their mouths, and they are more likely than adults to accidentally eat soil. Children are the most vulnerable to health effects from contaminated soil because their bodies are still developing.

Three studies have been completed in child-use areas: Vashon Island, Mainland King County, and Pierce County. For the most part, average concentrations of arsenic and lead in the surface soils are below the state cleanup levels. For those child-use areas with arsenic or lead above the state cleanup level, Ecology and the health departments recommend following the soil safety guidelines provided by the health departments. These are called Soil Safety Guidelines in King County and Healthy Actions in Pierce County.
Examples of the guidelines include:

• Wash hands after playing outside
• Take off or wipe off shoes when coming inside
• Wash toys small children play with
• Cover up bare soils

Local Health Department Web Links:

*A free version of Adobe Acrobat can be downloaded by clicking on the "Adobe Reader" link at left.