Abstract
For almost 100 years, the Asarco Company op-erated a copper smelter in Tacoma, Washington State. Air pollution from the smelter settled on the surface soil over more than 2,600 square kilometers of the Puget Sound basin. As part of the Tacoma Smelter Plume project, there have been a number of studies looking at soil ar-senic contamination, leading to the collection of more than 5,000 surface soil samples over the years. The present study aimed to pool all of the sampling results to create a model that can be used to further prioritize areas for ad-ditional sampling and remediation since not enough money is available to clean all residential parcels. This paper de-scribes a geostatistical simulation-based approach to com-pute for each block-group the expected number of residen-tial parcels where a given arsenic concentration threshold is exceeded with a minimum probability. This informa-tion is being currently used to select widely contaminated block-groups where all residential parcels are systemati-cally sampled and the ones exceeding a target threshold of 100 ppm are remediated.
