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Field Investigation Report Old Snelling Avenue and County Road E Improvements WSB Project No. R-015447-000 Page 6 3. Results 3.1 Soil Sample Results A total of 14 soil borings were advanced to depths of 16 feet below grade. Twenty-eight (28) soil samples were collected and submitted for laboratory analysis. Soil analytical results are summarized in Table 1, which also includes applicable MPCA Tier I Residential Soil Reference Values (SRVs), Tier II Industrial SRVs, and Screening Soil Leaching Values (SLVs). The laboratory analytical reports are included in Appendix C. The following is a summary of the soil sample results: · In general, geology at the Project Corridor consisted of sand (fine to medium grain) from the ground surface to depths ranging from 2 to 6 feet below grade. Soil underlying the sand consisted largely of silty and sandy clay to terminal depths of 16 feet below grade. Fill (sand, fine to medium grain) was noted in boring EB-3 from 1 to 15 feet below grade. · No elevated PID readings (> 10 parts per million (ppm)) were observed during the investigation. The highest reading (6.2 ppm) was detected at boring EB-2 from 0 to 2 feet below grade. PID screening results are included in boring logs in Appendix B. · A petroleum-like odor was observed in borings EB-1 from 5 to 9.5 feet below grade, EB-2 from 1 to 4.5 feet below grade, and EB-8 from 3 to 3.5 and 8.5 to 9.5 feet below grade. Black staining accompanied the petroleum-like odor in boring EB-1. No evidence of contamination was observed at the other boring locations. · Naphthalene was detected in soil sample EB-8 (2-4) at a concentration of 6.87 mg/kg, exceeding the Screening SLV of 4.5 mg/kg. Naphthalene was detected in soil samples EB-1 (6-8), EB-2 (2-4), and EB-8 (8-10) but at concentrations below the SRVs and SLV. No other VOCs were detected above laboratory reporting limits in the soil samples. · PAHs were detected above laboratory reporting limits in soil samples collected from borings EB-1, EB-2, EB-3, EB-5, EB-6, EB-8, and EB-9. Soil sample EB-3 (8-10) had a benzo(a)pyrene concentration of 6.08 mg/kg, exceeding the Tier II Industrial SRV of 3 mg/kg, and a BaP Equivalent concentration of 8.669 mg/kg, exceeding the Tier I Residential SRV of 2 mg/kg. Soil samples EB-8 (2-4) and EB-8 (8-10) had benzo(a)pyrene concentrations of 20.4 and 45.3 mg/kg, respectively, exceeding the Tier II Industrial SRV, and BaP Equivalent concentrations of 29.713 and 65.902 mg/kg, respectively, exceeding the Tier II Industrial SRV of 23 mg/kg. No other PAH detections in soil exceeded regulatory criteria. · Arsenic, barium, chromium, lead, and mercury were detected in multiple soil samples at concentrations above laboratory reporting limits but below regulatory criteria. · DRO was detected in soil samples EB-3 (8-10), EB-8 (2-4), and EB-8 (8-10) at concentrations of 102, 1,160, and 366 mg/kg, respectively, exceeding the MPCA criteria for unregulated fill of 100 mg/kg DRO. DRO was detected above laboratory reporting limits but below MPCA criteria in soil samples EB-1 (6-8), EB-2 (2-4), EB-3 (4-6), EB-5 (4-6), EB-5 (8-10), EB-12 (4-6), EB-13 (4-6), and EB-13 (8-10) at concentrations ranging from 7.53 to 79.8 mg/kg. · No GRO concentrations were detected above laboratory reporting limits in the samples. · No PCB concentrations were detected above laboratory reporting limits in the samples.