Preliminary Assessment and Site Investigation  Canyon City mill  

Contaminate of Concern

The results from the XRF were compared to the non-residential Arizona Soil Remediation Standards (AZSRS) and the EPA Ecological Soil Screening Levels (ECOSSL) in order to identify the human health and ecological COCs . For each sample, the highest and lowest results for each element were removed and the remaining data were averaged to provide the soil concentration. ECOSSL’s are broken down into four categories: mammal, avian, soil invertebrates, and plants. The following tables show the COCs for both humans and the ecology  :      

    Table 1: Human Health COCs

 Table 2: ECO-SSL Exceedances

  Migration Pathway Analysis

The soil type varied greatly across the site, but was consistently sandy and gravely, with some clay and organic material in DU1 and DU2. Wind causing dust entrainment of contaminated soils and downwind deposition is also a possible migration pathway of contaminant migration and could occur in the event of a high winds funneling through the hillsides over the site.The a wind rose below demonstrates that the majority of the wind occurring during 2022 in the area of the site comes from the southwest and northeast directions. Wind traveling from the northeast over the site would move contaminants attached to alluvial sediment to the southwest direction, which is into the wash that is southeast of the site and downstream. Wind traveling from the southwest would carry contaminated soil to the northeast direction.

 Figure 1: Wind Rose