1. Tacoma-Pierce County Health Department Presents… The Arsenic Project

2. A Brief History The Tacoma Smelter operated in Ruston, WA from 1890-1986 Specialized in smelting high arsenic ores Tall stack emissions from the plant contained arsenic, lead and other heavy metals. The purpose of the stack was to disburse emissions via the wind. In 1983 the smelter and surrounding area was designated an EPA Superfund Site

3. Previous Thinking on Contamination Fugitive emissions were problematic Not a lot of thought about the extent of low level contamination due to fallout from the plume Delineation of the superfund area was based on the extent of high levels of contamination due to fugitive emissions

4. An Evolution in Thought Several studies unrelated to the Asarco site indicated that the extent of the problem from the plant was much larger than originally thought Maury Island Gravel Pit Study University Place Water Tank Study University Place Residential Sampling

5. Realizing the Need For a Footprint Study Ecology realized results from other studies indicated wide- spread contamination over King and Pierce Counties Need for sampling outside the superfund area The Tacoma Smelter Plume Project (TSP) began It became the largest Site Hazard Assessment ever conducted in Washington State

6. Pierce County Footprint 2001- The Tacoma-Pierce County Health Department accepted an SHA grant to conduct the Pierce County Sampling The project became known as The Arsenic Project The scale of the project required a change in thinking about Site Hazard Assessments

7. Goals for the Footprint Study 1. Create a map of the “footprint” of contamination 2. Gather enough information to identify the PLP

8. New Sampling Methods Grid Sampling Divided the study area into 6 zones based on distance and direction from the stack and urbanization Grid spacing for each zone was dependent on expected variability of sample results

9. Depth Profiling New Sampling devices allowed discrete samples from three depths. Allowed a comparison of contamination between disturbed and undisturbed properties. Hypothesis that contamination on disturbed properties may be 6”-12” below the surface

10. Tracer Element Study Trace elements unique to the smelting processes and ores at the smelter provide a “fingerprint” to identify contamination The ratio of arsenic to antimony, indium, and bismuth provide credible evidence that the contamination came from the Asarco plant. Approximately 12% of the samples were sent for tracer analysis

11. Findings Low levels of arsenic contaminate soils in much of western Pierce County Contamination is found at higher levels and farther distances in the downwind directions Undisturbed properties generally have higher levels of arsenic than disturbed properties In disturbed areas the amount of arsenic in the soil is highly variable and dependent on property history

13. What We’re Doing With The Results… Footprint results were used to focus efforts for the Child Use Area Study and outreach and education activities Ecology is preparing a credible evidence report to identify the PLP.

14. Future Activities Complete the CUA Extend the footprint study Continue outreach and education activities Study remedial actions Tilling Bioremediation