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Limited Phase II Environmental Site Assessment 8 -Acre Property, Fairhaven Memorial, Santa Ana, California The State of California DTSC has also developed threshold levels for various pollutants in soil. The total threshold limit concentration (TTLC) and soluble threshold limit concentration (STLC) are used to determine whether excavated soil would be classified as a hazardous or non- hazardous waste for disposal purposes. The detected concentrations of pesticides in the soil samples collected and analyzed for pesticides were compared to the TTLC thresholds established by the DTSC. None of the detected concentrations of pesticides exceeded their respective l TTLCs nor were high enough to warrant soluble (STLC) analysis. Metals in Soil: Varying concentrations of metals were detected in the soil samples collected and analyzed for metals. The PRGs for residential and industrial settings for arsenic are 0.062 and 0.25 mg/kg, respectively. Background concentrations of arsenic found in western United States soils (non -contaminated sites) range from 0.10 to 97 mg/kg (Shacklette and Boemgen, Element Concentrations in Soils and Other Surficial Materials of the Conterminous United States, USGS, 1984). The USEPA states that generally they do not require cleanup below natural background levels. In light of this fact and in our experience, regulatory agencies typically consider the use of local or regional background concentrations as the threshold concentration for requiring further investigation or remediation. All of the analyzed soil samples detected arsenic concentrations above the PRGs for residential and industrial settings and all of the detected concentrations are within the range of naturally occurring background concentrations for arsenic in western United States soils. In addition, the levels of metals detected were compared to total threshold limit concentration levels established by the DTSC. The TTLC is used to determine whether excavated soil would be classified as a hazardous or non -hazardous waste for disposal purposes. STLC and TTLC levels for metals are listed in Table 2. Lead was detected in the 0.5 -foot sample from boring HA - 6 at a level that warranted soluble (STLC) analysis. The additional STLC analysis revealed non - detect levels of soluble lead. Metal concentrations detected for all of the other samples analyzed for metals did not exceed their respective TTLC levels and were not high enough to warrant soluble (STLC) analysis. CONCLUSIONS Based on the soil sampling and analysis for this Phase H ESA, the following has been concluded: • The levels of pesticides detected in soil samples collected from the subject property do not exceed PRG or TTLC thresholds established by the USEPA and DTSC. • The levels of metals identified in the soil samples collected from the subject property were within the published background ranges for metals in western United States soils. 0 Lead was detected in the 0.5 -foot samples collected from boring HA -6 at a level that warranted soluble (STLC) analysis. The additional STLC analysis revealed non -detect levels of soluble lead in that soil sample. Detected levels of metals in the other soil samples did not exceed PRG or TTLC thresholds established by the USEPA and DTSC. .J rRincon Consultants 31A-770