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1 <br /> ' 1444 MARIPOSA ROAD <br /> . WKA No 2938 06 <br /> September 6,2000 <br /> Page 7 <br /> The horizontal distances between the junction manhole and vapor extraction wells VEW1, <br /> ' VEW2, VEW3, MW1, and MW2 are approximately 30, 50, 40, 48, and 112 feet, respectively <br /> ' Two influent soil gas samples ASI and AS2 were obtained during the pilot test Sample <br /> AS 1 was obtained approximately 20 minutes into the test and sample AS2 was obtained at <br /> ' approximately 4 hours into the test The samples were obtained by connecting 1-liter <br /> Tedlar bags to the influent sampling port of the blower The samples were submitted under <br /> chain of custody to a Califorma-certified laboratory for analysis of TPH as gasoline and <br /> ' BTEX <br /> TPH as gasoline was detected in samples AS 1 and AS2 at concentrations of 3,316 ppm and <br /> 2,912 ppm,respectively Benzene was not detected in sample ASI but was detected in AS2 (8 <br /> ppmv) Low concentrations of toluene, ethylbenzene, and total xylenes ranging from 10 9 ppm <br /> to 51 ppm were detected in samples AS 1 and AS2 <br /> During the test, an average differential vacuum pressure of approximately 35 to 38 inches of HO <br /> was measured at the vapor extraction function manhole A vacuum extraction flow rate of <br /> ' approximately 280 standard cubic feet per minute (scfm)was observed in vapor extraction <br /> framework(manhole) Vacuum pressure and time were measured at the observation wells using <br /> Magnehelic pressure gauges The maximum observed vacuum pressure drawdowns in wells <br /> VEWI, VEW2, and VEW3 were approximately 10, 6 9, and 6 9 inches of HZO,respectively <br /> Based on data collected duringthe test a mininnurn radius of influence of approximately 50 feet <br /> � PP Y <br /> can be achieved using a vacuum pressure of at least 35-inches of water at the site <br /> ' Additional Soil Borings/Monitoring Wells <br /> On May 24 and 25, 1999, four soil borings B5 and MW4 through MW7 were drilled to depths <br /> ranging from 70 to 100 feet bsg(Plate 3). Groundwater was encountered in the bonngs at <br /> approximate depths of 47 to 48 feet bsg Soil boring B5 was drilled in the vicinity of the former <br /> 1 exploratory boring B 1 immediately east of the former UST excavation Borings MW4 and MW5 <br /> • were drilled along the northwest and southwest corners of the property, respectively, and borings <br /> WALLACE KUHL <br /> Kecycledpape &ASSOCIATES INC <br />