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					          Helter Smelter
Arsenic Contamination in Pierce County Soil: Is
       Environmental Justice Present?
                              MATH&146
         Temre Smith, Elizabeth Kalama-Wojtowicz, Erin Campbell
                               Dec 1, 2010
This study was done to determine whether or not arsenic levels in the soil effect home values. By
using random cluster sampling to find the mean home values in five different contamination levels, we
discovered that the contamination levels had no significant impact on home values.

 Abstract



Introduction
       The soil in Pierce County contains arsenic at levels up to 50 times higher than allowed by

the state. The most likely source of the contamination was Asarco’s copper smelting plant in

Ruston, near Tacoma. From 1890 to 1986, emissions from the plant, which included arsenic, lead

and other heavy metals, were probably carried by wind and deposited over Vashon and Maury

islands as well as mainland King and Pierce counties. The widespread soil contamination left by

the smelter is called the Tacoma Smelter plume site. In this study, we will be focusing on the

home values in some of these affected areas. We intend to determine if there is a connection

between home value and the level of arsenic contamination so we will be able to conclude if

people of lower incomes are subjected to more dangerous conditions. The study will be based on

assessments of property values taken randomly from the Pierce County Assessor’s Website in

October of 2010, http://www.co.pierce.wa.us/pc/abtus/ourorg/at/at.html, by using the parcel

numbers. To see if environmental justice is apparent within the areas contaminated with arsenic,

we will use home value as criteria to determine if there is a pattern between contamination levels

and level of income.


Methods

       Our study was conducted by examining the assessed property values for homes in North

Tacoma that were listed on the website for the Pierce County Assessor’s (PCA) office. These

samples were determined first by dividing a map provided by the Washington State Department
of Ecology that showed the different regions that were sampled during a study conducted in

2000. In this study there were soil samples taken from 59 residential yards. The 195 samples

were analyzed in a state Ecology Department-funded study to learn the extent of arsenic and lead

contamination around the now-closed Asarco copper smelter in Ruston. The average arsenic

concentration was 26.4 ppm, slightly above the 20-ppm cleanup standard. In 60 percent of the

yards sampled, average arsenic concentrations were over 20 ppm. However, in 80 percent of the

yards sampled, arsenic was below 40 ppm. The highest level measured was 1,050 ppm at a

Tacoma location.


        The map used was of North Tacoma and represented all five contamination levels that

were indicated in the 2000 study. We divided each area into a section approximately one square

mile and numbered them. After a single area was selected randomly from each of the five

contamination levels, those areas were then divided again into one block radiuses. That block

was then sampled on the PCA website. We divided the value of each house by the square

footage to obtain a value of each square foot. This was done to eliminate any bias that may have

been formed by comparing a three bedroom to a one bedroom ext.



                                                                    Legend
                                        Analysis

       In the five contamination levels there were seventy-one homes sampled. The median

range for all five levels was approximately the same ranging from 117 and 132 value per square

foot in dollars. The distribution of all the home values in the box plot below overlapped, showing

that the ranges are similar for all contamination levels.
                        The mean home values are provided below:

                   Level of Contamination      Mean Home Value     Standard Deviation

                 `Supersite                         123.48                23.32

                 Greater than 100. ppm              137.63                28.12

                 40.00 to 100.00 ppm                129.55                 8.01

                 20.1 to 40.00 ppm                  133.03                16.25

                 Not detected, < 20.0ppm             129.5                32.42



       A sample mean was used to determine if there were differences in property values in the

various arsenic contamination levels. Initially, we expected to find evidence that property values

in the areas most contaminated with arsenic would be lower than the property values in the areas

least contaminated with arsenic. However, there was not enough evidence to show that property

values were different. (p-value = 0.785924, F-value = 0.430736).


Conclusion

       When we first began to examine the North Tacoma area and the different property

values, it was our belief that there would be a difference of the housing values in the different

contamination levels. We were pleasantly surprised to discover that the hypothesis test indicated

that there were no clear differences of housing values in the areas of contamination. Because of

this, the results clearly show that environmental justice is present in North Tacoma.
                                          References

Background on Tacoma Smelter Plume. (2010). In Public Health- Seattle & King County.
    Retrieved September 15, 2010, from
    http://www.kingcounty.gov/healthservices/health/ehs/toxic/TacomaSmelterPlume/backgrou
    nd.aspx.

Dirt Alert- Tacoma Smelter Plume Interactive Map. (2010). In Department of Ecology State of
     Washington. Retrieved September 18, 2010, from
     http://apps.ecy.wa.gov/website/facsite/viewer.htm?sp_area=Tacoma%20Smelter%20Plume

Parcel Search. (2010). In Pierce County Assessor's Treasury. Retrieved October 15, 2010, from
     http://www.co.pierce.wa.us/pc/abtus/ourorg/at/at.htm.
Home values and listings. (2010). In Zillow.com. Retrieved November 6, 2010, from
   http://www.zillow.com/

				
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