Red Wing: Western End Main Production Area. Soils were excavated from the areas surrounding borings B1604 and B1605 in the western portion of the former Red Wing on October 30, 2008. An area approximately 40’ in length and 20’ in width was excavated to a depth of 3.5 feet in the vicinity of boring B1604 to address metals concentrations in exceedance of the commercial-use SCO for nickel detected at the 2.0’ – 2.5’ interval identified during the October 2006 remedial investigation. Adjacent to the southern boundary of this excavation, an additional 15’ by 20’ area proximate to boring B1605 was excavated to a depth of 5.0 feet to address reported exceedances of the commercial-use SCO for cadmium in the 2.0’ – 4.0’ interval. A total of six post-cleanup verification soil samples were collected for PPMs+Ba analysis immediately following the excavation of both areas, including one basal sample (1604-PE03) at the 3.5’ – 4.0’ interval from the center of the northern “B1604” excavation, one basal sample (1605-PE03) at the 5.0’ – 5.5’ interval from the center of the southern “B1605” excavation, and four sidewall samples from 2.0’ – 2.5’ and 3.0’ – 3.5’. As shown on Figure 7, no samples were collected from the “B1604” excavated area from the western sidewall, as a concrete footer extended to a depth of approximately 3.5’ along the entire length of the excavation. As such, only one sidewall sample, 1605-PE02 in the southern-most “B1605” area excavation, was collected, targeting the 4.0’ – 4.5’ interval at the western sidewall. Analytical results for samples collected in the B1604 and B1605 area excavations are presented in Appendix B and on Figure 7. Reported metals concentrations were below the commercial- use SCOs for all constituents in the B1605 excavation. In the B1604 excavation, one base sample and its duplicate, 1604-PE03, had nickel concentrations of 349 mg/kg and 356 mg/kg, slightly above the commercial-use SCO of 310 mg/kg. In addition, sidewall samples 1604- PE01, 1604-PE02 and 1604-PE03 had cadmium concentrations above the commercial-use SCO at 2.0’ – 2.5’ and/or 3.0’ – 3.5’. Further excavation was therefore conducted in the base and along the western wall of the “B1604” area on November 4, 2008. The depth of the excavation was extended an additional one foot, to a total depth of 5 feet. The western edge of the additional excavation extended to an interior footing wall that extended to a depth of approximately 4.5 feet, such all remaining impacted soils were removed, with additional sidewall post-ex...
