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under direct supervision of a California Registered Civil <br /> Engineer Groundwater contours were constructed using a <br /> kriging program ( Figure 5 ) . <br /> Subsequent to monitoring well installation and development, <br /> water samples were collected after purging a minimum of four <br /> well volumes (casing and sand pack ) from each well . Purged <br /> water was placed in a 55-gallon drum and stored on-site. <br /> Water sample collection and preservation is in accordance <br /> with WaterWork' s Groundwater Sampling Protocol (Appendix <br /> III ) . The water samples were analyzed for BTEX and TPH as <br /> gasoline. The minimum detection level for BTEX is 0. 3 ppb, <br /> and 30 ppb for TPHG. <br /> 3.4 Quality Assurance/Quality Control Program <br /> Sailers with bottom emptying devices to reduce <br /> volatilization were used for water sample collection. <br /> Groundwater was monitored in accordance with WaterWork' s <br /> Groundwater Sampling Protocol (Appendix III ) . No replicate <br /> samples were submitted for analysis. <br /> The field investigation was conducted under the direct <br /> supervision of Russell W. duncal , Cdlifornia Registered <br /> Geologist No. 3864, and Nora H . Kataoka, California <br /> Registered Civil Engineer No. 38322. <br /> 4.0 RESULTS OF INVESTIGATION <br /> 4.1 Laboratory Analysis <br /> 4 . 1. 1 Soils <br /> Subsurface soil samples from MW1 , MW2 , and MW3 were <br /> submitted to Sequoia Analytical Laboratories for analysis. <br /> Laboratory analysis of soils indicate well MW1 rad <br /> detectable levels of BTEX and TPHG at 10.5 foot below grade. <br /> MW2 had low levels of toluene, e-hylbenzene, and xylenes and <br /> TPHG. MW3 had detectable levels of xylenes and TPHG at 5. 5 <br /> feet and detectable levels of xylenes at 10. 5 feet. Results <br /> are summarized on Table 1. Laboratory reports and chain-of-- <br /> custody forms are contained in Appendix 0. <br /> 4. 1.2 Groundwater <br /> Groundwater samples were collected from each well after well <br /> installation and development and were submitted to Sequoia <br /> Analytical for analysis. Well MW1, which is downgradient of <br /> the former tank location, had detectable levels of BTEX and <br /> TPHG. Wells MW2 and MW3 indicated non-detectable levels in <br /> all areas. Results are summarized on Table 2. After the <br /> groundwater was sampled it was noted that the covers on the <br /> wells had been inadvertently switched. The data presented <br /> in Table 2 represents the actual groundwater analysis <br />