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05 May 1997 <br /> AGE-NC Project No 95-0173 <br /> Page 6 of 29 <br />' 33 COLLECTION AND ANALYSIS OF VAPOR SAMPLES <br /> A total of four vapor samples were collected at two-hour intervals from the inlet of the extraction <br /> well to measure concentrations of extracted hydrocarbon vapor The samples were collected in <br /> Tedlar bags using the organic vapor analyzer as an air pump <br />' Following sample collection,the samples were placed in a covered container and transported under <br /> chain-of-custody to McCampbell Analytical Inc (MAI) in Pacheco, California Each sample was <br /> analyzed within 72 hours for TPH-g and BTE&X with methyl tertiary butyl ether (MTBE) in <br />' accordance with EPA Methods 8015m and 8020, respectively, TPH-d was analyzed from one <br /> selected sample in accordance with EPA Method 8015m <br /> 34 RESULTS OF VAPOR EXTRACTION PILOT TEST <br />' During the vapor extraction pilot test, VW-I was selected as the extraction well Flog rates ranged <br /> from 27 to 58 standard cubic feet per minute (scfm) at 0 25 to 1 25 inches of water of differential <br /> pressure The induced vacuum stabilized at approximately 35 inches of water during the pilot test <br /> Hydrocarbon concentrations in the well effluent stream were measured at regular inter,als PID field <br /> measurements ranged from 173 to 1,328 parts per million (ppm) Field measurements are <br /> summarized in Table 5 <br /> Induced vacuum measurements were recorded from wells VW-1, V W-2 and MW-1 through MW-4 <br /> utilizing magnehelic gauges The greatest vacuum measurements were observed from VW-1 at <br /> approximately 45 inches of water Vacuum measurements were observed from VW-2 (located <br /> approximately 26 feet west of VW-1) at approximatel inches of water <br /> 1 Minimal induced vacuum measurements were observed from MW-2 and MW-3 (located <br /> approximately 32 and 38 feet southwest and east, respectively, from VW-1) at approximately 0 015 <br /> 1 inches of water No significant vacuum measurements were reported from MW-4, located <br /> approximately 65 feet from VW-1 _ <br /> s-i : t rt r y 4 ] ] a i7ii7 rf 11 iii 7 n„A NAN11 ? itrara arart}ir�rl <br /> I lie vacuum cipplleu at V W-1 dila ute induced vacuums at Y YY-2, i� rr-L culu ASA ..a� ,..,., b...r..... <br /> versus distance utilizing a best fire line on a semi-logarithmic scale (See Figure 4) Based upon the <br />' induced vacuums measured from VW-2,MW-2 and MW-3, a theoretical radius of influence in soils <br /> at the site for an applied vacuum of 45 inches of water is 30 feet for an induced vacuum of 0 1 inches <br /> F <br /> vi wdtGr <br /> 1 <br /> FROI <br /> • <br /> 1 <br /> Advanced CeoEn%tronmental,Inc <br />