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CAMBRIA <br /> of this investigation are presented in Cambria's Fourth Quarter 2001 Groundwater <br /> Monitoring/Sate Investigation Report and Receptor Survey, dated January 11, 2002 <br /> During August 2002, Cambria installed wells MW-8 and MW-9 across Pacific Avenue from the <br /> subject site Cambria details this investigation in our January 6, 2003 Site Investigation and <br /> Third Quarter 2003 Groundwater Monitoring Report <br /> Groundwater Monitoring Program <br /> There are currently four monitoring wells onsite (MW-1 through MW-4), seven offsite <br /> monitoring wells (MW-5 through MW-11), and one onsite soil vapor extraction (SVE) well <br /> (VEW-2), which are monitored and sampled quarterly Dunng the second quarter 2003 sampling <br /> event,TPHg was detected in wells MW-1, MW-3 through MW-11, and VEW-2 at concentrations <br /> ranging from 67 to 82,900 ppb The laboratory notes that the TPHg reported in wells MW-6 and <br /> MW-8 through MW-11 are primarily due to the presence of tetrachloroethene (PCE) Benzene <br /> was detected in wells MW-1, MW-3 through MW-10, and VEW-2 from 0 72 to 1, 600 ppb Well <br /> MW-4 also contained 20 ppb methyl tertiary butyl ether(MTBE) <br /> • Groundwater Definition Status <br /> Lateral Definition Wells MW-1 and MW-2 define TPHg and MTBE in groundwater below <br /> detection limits and benzene to less than 1 ppb at the northern boundary of the site Well MW-5 <br /> defines MTBE below detection limits, TPHg below 70 ppb, and benzene below 2 ppb at the <br /> western boundary of the site No groundwater monitoring wells have been installed east of the <br /> existing USTs This is proposed below <br /> As discussed previously, wells MW-6 and MW-8 through MW-11 contain TPHg, which is <br /> primarily due to the presence of PCE Cambria maintains that the PCE is not associated with the <br /> subject site, and that the edge of the Shell plume is likely located near MW-6 Well MW-8 <br /> defines MTBE in groundwater downgradient of MW-4 below detection limits and benzene to <br /> below 2 ppb Therefore, at this time, we are not proposing further investigation south or <br /> southeast of the subject site <br /> Vertical Definition MTBE is vertically defined in groundwater above 60 fbg in CPT boring <br /> SB-6 However, TPHg and benzene were detected in the groundwater samples collected at <br /> 97 fbg in borings SB-5 and SB-6 A deep well is proposed below <br /> 0854 3 <br />