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characterize the subsurface vadose zone soils, 2) to investigate <br /> the possible impact of hydrocarbons on groundwater beneath the <br /> site, and 3) to determine the hydraulic gradient of first <br /> groundwater. <br /> TPE conducted the following tasks while performing the above <br /> ' scope of work: <br /> Conducted a subsurface utility survey to minimize the <br /> ' potential of encountering underground utilities and to <br /> assist in selecting locations for the 3 monitoring well <br /> borings. <br /> ' Drilled 3 soil borings for the construction of 3 <br /> groundwater monitoring wells (MW-4, MW--5, and MW-6) . <br /> Collected soil samples at approximately 5-foot or less <br /> ' depth intervals, and/or changes in lithology for <br /> determining the geologic profile and for field <br /> screening soil samples with a GasTech combustible gas <br /> indicator (CGI) for hydrocarbon contamination. <br /> Collected a total of 18 split spoon soil samples from <br /> the 3 monitoring well borings and submitted 4 samples <br /> (at least one from each boring) for petroleum <br /> hydrocarbon chemical analyses. Additionally, the <br /> sample showing the highest CGI reading was analyzed for <br /> total lead. <br /> Converted the above referenced soil borings into <br /> monitoring wells to evaluate groundwater quality with <br /> ' respect to total petroleum hydrocarbons as gasoline <br /> (TPHG) and benzene, toluene, ethylbenzene, and xylenes <br /> (BTEX) . <br /> Developed monitoring wells MW--4 through MW-6. <br /> Surveyed the elevations of the above referenced wells <br /> top-of-casing (TOC) to the nearest . 01 foot above mean <br /> sea level (MSL) and surveyed their horizontal positions <br /> relative to the city of Manteca reference benchmark # <br /> ' 47 . <br /> Measured the depth to stabilized groundwater in the 3 <br /> wells. <br /> Purged and sampled monitoring wells MW-4 through MW-6. <br /> II . : Analyzed the, groundwater samplesfor TPHG and BTEX. <br /> IE 11 i I <br /> 'II Calculated direction and gradient of groundwaten flow <br /> beneath the site. 1 <br /> 2 <br /> t <br /> I ! I I <br /> ,� f��1 ' iII � �EI i , � I� I I 1111 11 ,IlI �'� � i�11 � 91 Ii II I � III � P � I � ' E <br /> I Ea IE I4 , I I I,VIt �,�II ii il' I'I II II`r 11 it, , I `1 � E ,iF I 11it I II <br /> ' I I li i I1 li II II I i I I 1I 1'i II i ! 1` I f I' I I I I I <br /> I � I <br />