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1 <br /> Geological r"Afild bw Page 15 <br /> Site Conceptual Model Report(2006 Revision) <br /> Valentine(Castle Motors) <br /> Project No 723 2 <br /> June 21,2006 _ <br /> MW-8: TPH-G vs. Elevation <br /> ' 6000 - —— — 0 <br /> 5000 -5 <br /> ' 4000 -10 <br /> v -- <br /> 3000 -15 ■ TPH-G <br /> ' D. 2000 -20 GW elevation <br /> t— <br /> W <br /> 1000 1 • -A- * "• -25 <br /> 0 -30 <br /> r <br /> 0 0 o Q s <br /> Date <br /> This graph shows an increasing trend with a large spike in TPH-G concentrations on January <br /> 17, 2006 The rising trend could represent the edge of the plume naturally migrating <br /> northeast across N El Dorado Street for which transport calculations could be attempted <br />' However, this situation was complicated due to other factors that coincided with the increase <br /> in TPH-G in MW-8 During CPT activities in February 2006 a subsurface water leak was <br /> noted beneath the sidewalk/El Dorado Street next to the subject site (see photo below) GTI <br />' notified the SJC/EHD and also the City water company (CWSC) and requested that it be <br /> fixed ASAP A site inspection on March 9, 2006 noted that it had been fixed It is possible <br /> that the spike in contaminant concentrations was due to a flushing of the soil column from <br /> the pipeline water leak next to the site Additional monitoring will show whether the spike <br /> was an anomaly potentially caused by the water leak or if in fact the core of the contaminant <br /> plume is displaced from under the dispenser island <br /> 1 <br />