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' l <br /> ' GEOMATRIX <br /> 1 Previous site investigations had not been conducted at the Arcos property. The purpose of the <br /> 1 recent Arcos property investigation was to characterize the property in accordance with <br /> l ChevronTexaco's revised Consistent Technical Approach (CTA)that is typically applied at <br /> l ChevronTexaco historical pipeline sites (Geomatrix, 2002b). The Arcos property investigation <br /> r and results are presented in Section 3.0. <br /> 2.0 BELLINI PROPERTY INVESTIGATION <br /> A summary of previous investigations; the objectives, field and analytical methods; and the <br /> results of the 2003 Bellini property investigation are presented in the following four sections. <br /> -� 2.1 PREVIOUS INVESTIGATIONS <br /> Various investigations have been conducted at the Bellini property since 1995 (Geological <br /> Technics, 1995; Radian, 1998; Geomatrix, 2002a). Two borings (SB-1 and SB-2) were <br /> advanced for soil sampling in 1995. Six borings (SB-3 through SB-8) were advanced for soil <br /> sampling and four groundwater monitoring wells (MW-1 through MW-4) were installed in <br /> 1998. In 2002, Geomatrix collected soil samples from six borings (SB-9 through SB-14), <br /> collected one grab groundwater sample from SB-13, and collected groundwater samples from <br /> the monitoring wells. The locations of these borings and wells are shown on Figure 3. <br /> Groundwater has been encountered in on-site monitoring wells MW-1 through MW-4 from <br /> about 31 to 37 feet bgs, and groundwater flow direction varies from east to northeast. <br /> Historical well survey and groundwater elevation data, along with the screened interval for <br /> each well, is provided in Table 1. <br /> }! Based on the results of the previous investigations (Tables 2 and 3), concentrations of total <br /> petroleum hydrocarbons (TPH) quantified as diesel, motor oil, and/or crude oil (TPHd, <br /> TPHmo, and/or TPHc, respectively) exceeding 100 milligrams per kilogram(mg/kg) were <br /> detected in some of the soil samples collected from borings MW-1,MW-2, SB-2, SB-4, SB-8, <br /> SB-9, SB-10, and SB-14. The estimated lateral extent of affected soil is shown on Figure 3: <br /> . The deepest boring (SB-9) was advanced to about 81 feet bgs. TPHc concentrations were less <br /> than 100 mg/kg in the soil samples collected at 70.5 and 81 feet bgs from SB-9. Based on these <br /> lresults, the vertical extent of soil affected by high TPH concentrations (e.g., exceeding <br /> 1,000 mg/kg) is limited to between about 5 and 70 feet bgs within the property. <br /> -.1 Groundwater data are summarized in Tables 4 and 5. Well MW-1 is located within an affected <br /> soil area and has not been sampled due to the presence of separate-phase petroleum in the well. <br /> 1:\PROJEC,5000s\5011.0006011-03.do 4 <br />