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EnviroTech Consultants, Inc. Page 12 <br /> Site Investigation: Sampling Report <br /> Louise Avenue Water Treatment Facility <br /> 3.2 Initial Sampling Soil Analytical Results Summary <br /> The San Francisco Bay Regional Water Quality Control Board (SFBRWQCB) Environmental Screening <br /> Level (ESL) for Direct Exposure - Dermal Contact for a Construction Worker is 10 mg/kg for arsenic (Soil <br /> Direct Exposure S-1, February 2016)2. EPA Carcinogenic Target Risk Dermal Screening Levels for arsenic <br /> is 17 mg/kg.These ESL values are used in this study as the minimum indicators for arsenic concentrations <br /> of concern. The SFBRWQCB does not currently have an ESL indicator for direct exposure for vanadium. <br /> The Total Threshold Limit Concentration (TTLC)for Vanadium is 2,400 mg/kg. <br /> Table 1 summarizes the soil sample analytical results and includes the SFBRWQCB ESLs for Direct <br /> Exposure Soil for Construction/Trench Worker and the EPA Carcinogenic Target Risk Dermal Screening <br /> Levels for comparison. The complete laboratory reports are included in Attachment 2. <br /> Four of the 24 samples collected in Area 1, (COI-1-2, COI-1-4, COI-1-9, and COI-11-12) contained <br /> concentrations of arsenic that exceeds the SFBRWQCB ESL threshold but did not exceed the EPA dermal <br /> screening level. The highest concentration of arsenic detected was 15 mg/kg in the sample collected from <br /> the surface to 6 inches bgs at COI-1-9. <br /> In Area 2, the duplicate sample collected from the surface to 6 inches bgs at COI-2-1 had a concentration <br /> of arsenic of 30 mg/kg. This concentration exceeds both the SFBRWQCB ESL threshold and the EPA <br /> dermal screening level. <br /> In Area 3, three of the nine samples collected contained concentrations of arsenic that exceed the <br /> SFBRWQCB ESL but not the EPA dermal screening level. Five of the nine samples collected contained <br /> concentrations of arsenic that exceeds both the SFBRWQCB ESL and the EPA dermal screening level. <br /> Samples collected from COI-3-1 and COI-3-4 contained arsenic concentrations over the Soluble Threshold <br /> Limit Concentration (STLC)of 5 mg/L. A sample could not be collected from 1 to 2 feet bgs at COI-3-4 due <br /> to large cobbles at that location. <br /> The background sample collected from the surface to 6 inches bgs, contained concentrations of arsenic <br /> that exceeds the SFBRWQB ESL threshold but not the EPA dermal screening level. <br /> Vanadium concentrations detected in all of the samples did not exceed the TTLC of 2,400 mg/kg. There is <br /> no EPA Dermal Screening Level for vanadium. <br /> 2 The San Francisco Bay Regional Water Quality Control Board (SFBRWQCB) Environmental Screening Levels (ESLs)Workbook <br /> was updated on January,24,2019.The ESL for Direct Exposure—Dermal Contact for a Construction Worker for arsenic is the same <br /> as the February 2016 ESL. <br /> 5400 Rosedale Highway Bakersfield, CA 93308 Tel 661.377.0073 Fax 661.377.0074 <br />