WA State Dept of Ecology 9/18/2023

Joel Haack January 6, 2023 Page 3 Analysis of the Cleanup Ecology has concluded that no further remedial action is necessary at the Property to clean up contamination associated with the Site. However, Ecology has also concluded that further remedial action is still necessary to clean up contamination elsewhere at the Site. Ecology bases its conclusions on the following analysis: Characterizing the Site Ecology has determined your completed Site characterization is sufficient for setting cleanup standards for the Site and selecting a cleanup action for the Property. Enclosure C describes the Site. • Soil. From 1894 to 1912, operations at the Asarco Everett Smelter resulted in the release of arsenic, lead, and cadmium to shallow soils. Particulate matter from smokestack emissions containing high amounts of these metals settled onto the surrounding area, resulting in contamination to shallow soils.The Property is located approximately 0.5 miles west of the location of the former smelter, within the known extent of arsenic, lead, and cadmium contamination. Characterization activities conducted at the Site in 1995 and 2008 indicated that soil contaminated with arsenic above the Method A cleanup level was present at the Property. Further soil characterization activities conducted in January 2021 at the Property confirmed arsenic, lead, and cadmium were present on the Property at depths from 0.5 to 5 feet below ground surface (bgs). Performance soil samples collected during remedial excavations conducted at the Site in October 2021 defined the lateral and vertical extent of soil contamination on the Property, and confirmed that all contaminated soils within the Property boundary were removed from the Property. • Groundwater. Based on the results of previous investigations conducted at the Site, groundwater is not expected to be impacted by soil contamination. Groundwater was not encountered in any borings or excavations on the Property. Based on the results of previous investigations, groundwater is located more than 50 feet bgs in this portion of the Site. Setting cleanup standards for the Site Ecology has determined the cleanup levels and points of compliance you set for the Site meet the substantive requirements of MTCA.