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Mr Jeffrey Wong <br /> C A M B R I A February 23, 2006 <br /> December 31, 2005, the temporary GWE system has removed approximately 2 4 pounds of <br /> MTBE and 7 1 pounds of TBA Grab groundwater laboratory analytical reports are included as <br /> Attachment i <br /> INVESTIGATION RESULTS <br /> Analytical Results in Soil MTBE was detected in three samples from boring SB-6 at <br /> concentrations ranging from 0 47 to 1 1 ppm at depths from 34 to 54 fbg MTBE was also <br /> detected in the 54-fbg sample from well boring MW-13 at 00059 ppm TBA was detected in two <br /> samples (at 39 and 54 fbg) in boring SB-6 at concentrations of 6 3 and 15 ppm, respectively No <br /> TPHg, BTEX, DIPE, ETBE, TAME, 1,2-DCA, or EDB were detected in any soil samples <br /> collected during this investigation <br /> Table 2 presents soil analytical data, TPHg, benzene, MTBE, and TBA concentrations are shown <br /> on Figure 2, and the laboratory analytical reports are included in Attachment E <br /> Analytical Results in Groundwater MTBE was detected in groundwater samples from wells <br /> . MW-1 through MW-5, MW-7, and MW-13, MW-14, MW-15, P-1, and P-2 at concentrations <br /> ranging from 1 S to 24,000 ppb TBA was detected in wells MW-1, MW-2, MW-4, MW-15, P-1, <br /> and P-2 at concentrations ranging from 14 to 140,000 ppb The laboratory noted that the initial <br /> analyses for groundwater samples from P-1 and P-2 were within hold time but additional dilution <br /> was required TPHg was in well MW-15 at 52 ppb Benzene, 1,2-DCA, and EDB were not <br /> detected in groundwater samples from wells MW-12 through MW-15 TPHg and BTEX analyses <br /> are performed annually in wells MW-1 through MW-11, P-1, and P-2 during the first quarter <br /> The groundwater chermcal analytical data are summarized in the well concentrations table in <br /> Blaine's report (Attachment C} MTBE and TBA concentrations are shown on Figure 3 The <br /> laboratory analytical report is also included in Blaine's report (Attachment Q <br /> SITE CONCEPTUAL MODEL <br /> Item Evaluation Criteria Comments/Discussion <br /> 1 Hydrocarbon Source <br /> 1 1 Identify/Describe Release Source Soil data from the December 1994 tank removal and <br /> and Volume (if known} soil borings drilled near the USTs in February 1996, <br /> January 1999, and November 1999 suggest that the <br /> former USTs are the likely source of the petroleum <br /> hydrocarbons and fuel oxygenates detected in <br /> 9 <br />