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1 <br /> Gealagicat Technus Inc Page 2 <br /> Valentine(Castle Motors) <br /> ' Report—Additional Site Characterization <br /> Project No 723 2 <br /> January 21,2004 <br /> 1 In October 1993, four boreholes (SB-1 thru SB-4) were placed around the location <br /> of the former waste oil tank Results showed that all soil samples, except for the 36- <br /> foot sample from SB-2, were below detection limits for BTEX and TPH-G <br /> O In September 1994, monitoring well MWA was installed at the site Soil sample <br /> analytical results indicated the presence of BTEX and TPH-G in the soil to a depth <br /> of 56 feet bgs Waste oil was detected in the shallow soil samples <br /> • In June 1995, two additional monitoring wells, MW-2 & MW-3, were installed at the <br /> site Results showed the presence of high levels of BTEX and TPH-G in the soil and <br /> groundwater <br /> 0 In June 1996, three additional monitoring wells (MW-4, MW-5 & MW-6) and soil <br /> boring `B" were installed at the site Soil sample analytical results indicated the <br /> ' presence of significant levels of BTEX, MTBE and TPH-G The results also <br /> indicated that the pump-island was a mayor source of contamination <br /> 0 In September and October 1997, five Strataprobe soil borings (SP-1, SP-4 SP-5, SP- <br /> 5A & SP-6) were installed at the site Groundwater samples collected from these <br /> borings indicated the presence of low to moderate levels of TPH-G to a depth of 60 <br /> feet bgs <br /> ' • In August 1999, one deep screened monitoring well (MW-101) and one soil boring <br /> SB-201 were installed at the site The purpose of these borings was to define the <br /> vertical extent of the groundwater plume Soil samples collected by use of the <br /> SimulProbe' Maxitool from the soil borings tested positive for BTEX and TPH-G <br /> compounds to a depth of 111 feet Porewater samples, also collected with the <br /> SimulProbe, revealed the presence of BTEX and TPH-G to a depth of 1 11 feet bgs <br /> + An abandoned domestic well located at an adjacent residence was destroyed in <br /> ' accordance with SJC/EHD directives on April 20, 2001 <br /> • A discretely screened deep well (MW-201) was installed in October 2001 The <br /> results of this endeavor suggested that the contamination extended to a depth of 128 <br /> feet below grade surface (bgs) This depth was the target of a SimulProbe sampling <br /> effort and the soil sample from this elevation contained detectable TPH-G <br /> • Nine quarterly monitoring events have been completed since the installation of deep <br /> ' well MW-201 This well was completed with a screened interval of 148 — 150 5 feet <br /> bgs The contaminant concentration decline since the first monitoring event in <br /> December 2001 supports the conclusion that the initial high concentrations were <br /> ' from a drilling artifact The well currently contains trace to non-detect <br /> concentrations of contaminants <br /> In their letter correspondence dated April 29, 2002, the SJC/EHD instructed Mr Valentine <br /> ' to submit a work plan for additional site characterization The directive contained the <br /> following specific elements <br /> I The work plan must address the definition of the vertical and lateral extent of the <br /> contamination under the same scope of work, <br /> 2 The vertical extent of the contamination must be defined first, with lateral definition <br /> ' to follow, <br /> 3 A site conceptual model with geologic cross sections must be included <br />