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Kennedy/Jenks Consultants <br /> 5.3.1 OU-1 AOI 1 <br /> None of the eight soil samples collected from the two borings advanced in the previously <br /> remediated soils in AOI 1 contained total lead at concentrations exceeding the comparison <br /> values. The largest total lead concentration in these samples was 23 mg/kg and the largest <br /> soluble lead concentration in these samples was 0.75 mg/I. <br /> 5.3.2 OU-1 AOI 2 <br /> Six soil samples collected from the six borings advanced in AOI 2 (the stabilized lead area) <br /> ' contained lead at concentrations exceeding the residential PRG and CHHSL of 150 mg/kg and <br /> the former remediation goal of 220 mg/kg. These six samples were collected near the surface <br /> (i.e., at depths less than 3 feet bgs). In borings where deeper soil samples were collected and <br /> analyzed, the total lead concentrations in the deeper soil samples were less than 15 mg/kg. <br /> Deeper samples were not collected from two borings due to mechanical refusal. <br /> ' 5.3.3 OU-1 AOI 3 <br /> Ten borings were drilled in AOI 3 around the previously remediated area, where soil had been <br /> characterized as having elevated lead concentrations. <br /> The highest concentrations of lead in 01-1-1 are evident in soil samples collected in AOI 3 near <br /> AOI 2. Generally, shallow soil samples collected in AOI 3 from borings near AOI 2 had elevated <br /> lead concentrations and the soil samples farther from AOI 2 contained much lower <br /> concentrations of lead. <br /> ' With the exception of Boring OU1-AO13-S9, the available data from eight soil borings advanced <br /> in AOI 3 indicate that where elevated lead concentrations were encountered in shallow soil <br /> samples, much lower lead concentrations were observed in samples collected from deeper <br /> sampling intervals in the same borings. Mechanical refusal was reached in two borings, <br /> 0U1-A013-S1 and 01-11-A013-S2, at depths of approximately 2.5 feet bgs. <br /> 5.4 Operable Unit 2 <br /> As described in Section 2, 01-1-2 represents what appears to be the primary former industrial <br /> area of the Railyard, and was divided into five AOIs (AOI 4 through AOI 8) based on prior uses. <br /> Analytical results from soil samples collected in 01-1-2 are summarized in Table 6 (metals) and <br /> Table 7 (organic compounds). Table 6 includes PRG and CHHSL values for comparison; <br /> Table 7 includes PRGs only as comparison values as CHHSLs have not been established for <br /> the organic compounds detected in the samples at concentrations exceeding analytical <br /> ' reporting limits. Although shallow groundwater beneath the Railyard may not be considered a <br /> potential source of drinking water, analytical results for groundwater samples are summarized in <br /> Table 8 with available Maximum Contaminant Limits (MCLs) as comparison values. <br /> ' Concentrations of lead in shallow soil are presented on Figure 5, and concentrations of TPH <br /> • compounds in groundwater in 01-1-2 are presented on Figure 6. Data from borings advanced in <br /> eastern 01-1-5, and data from borings advanced by Geocon in 2005 in OU-3 and OU-4 are also <br /> DRAFT Phase I Remedial Investigation Report Page 23 <br /> Former Tracy Railyard, Tracy, California <br /> g:1is-groupladminyob10510565777.18_uprr109-reportslri rpNext.doc <br />