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3. MW-3 — showed a similar pattern of MW-1, being non-detect to the depth of 20 feet; <br /> however, at 25 feet concentration of BTEX and TPH-G were dramatically higher. <br /> 4. MW-4 & MW-5 — samples in.the upper 40 feet were non-detect for the volatile <br /> compound, however these data show slightly elevated detection limits; still under the <br /> thresholds shown in the table above <br /> It is noted that Napthalene and PAH's were historically not included in the compounds of <br /> concern during the 1990s and therefore, were not analyzed. <br /> We conclude that even though the site does not have direct measure of petroleum vapor <br /> concentrations in the soil around this building, vapor intrusion does not pose a threat. The <br /> reasons for this conclusion are: <br /> 1. The site has a nearly complete lack of volatile compounds in the soil around the <br /> building to a depth of 40 feet for the most part; with the exception that contamination <br /> in MW-3 is encountered at 25 feet. <br /> 2. Therefore, the condition of the upper soil,horizons of this site creates a significant <br /> buffer of soil between the contaminated zone and the floor of the building, where <br /> natural attenuation processes will mitigate any potential risk of petroleum vapor <br /> migrating up through the soil prior to intrusion into the building. <br /> 3. Additionally, extensive remediation has occurred at this site,that has removed much <br /> of the contamination found in the deeper soil horizons, which further reduces the <br /> perceived risk of vapor intrusion. <br /> t this site be closed without further delay. �������® <br /> We recommend that <br /> JUN 3 0 2014 <br /> Respectfully submitted, <br /> f �� NAIL GFO/. ENVIRONMENTAL HEALTH <br /> Lt PERMIT/SERVICES <br /> 4V4 Lr�-. RAYNOLq I. <br /> Raynold 1. Kablanow II, Ph.D. a0 KNo.523523W <br /> No. 4 <br /> California Registered Geologist #5234 J, <br /> Certified Hydrogeologist #442 �,�� �-a)P' pQ� <br /> cc: Steve Valentine <br /> Vicki McCartney— SJ EHD <br /> James Barton - CRWQCB-CVR <br /> 6�r <br />