Date post: | 29-Jan-2016 |
Category: |
Documents |
Upload: | brittany-evans |
View: | 222 times |
Download: | 0 times |
Tacoma-Pierce County Health Department Presents…
The Arsenic
Project
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
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
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
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 areaThe Tacoma Smelter Plume Project (TSP) beganIt became the largest Site Hazard Assessment ever conducted in Washington State
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
Goals for the Footprint Study
1. Create a map of the “footprint” of contamination
2. Gather enough information to identify the PLP
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
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
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
Findings
Low levels of arsenic contaminate soils in much of western Pierce CountyContamination is found at higher levels and farther distances in the downwind directionsUndisturbed 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
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.
Future Activities
Complete the CUA
Extend the footprint study
Continue outreach and education activities
Study remedial actions Tilling Bioremediation