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3 <br /> J <br /> (i W <br /> EE� <br /> f ! <br /> "arding Lawson Associates <br /> III. FIELD OPERATIONS <br /> E , <br /> During June and July 1988 HLA conducted+ a supplemental <br /> t.; field investigation consisting of a soil- <br /> gas survey, eight addi- <br /> tional s baring and g water cam soil round- lin <br /> ;...; A g, and chemical <br /> analyses. Seven borings were converted to monitoring wells. The <br /> eighth was grouted to its full depth after sampling. <br /> F <br /> A. Soil--Gas Surve <br /> In July 1988, HLA conducted a soil- as survey g Y as a first <br /> x ` ! step in evaluating the areal extent of gasoline h <br /> s ir! <br /> ydrocarbons in <br /> soil and ground water - <br /> . A soil <br /> gas survey detects volatile <br /> organic chemicals (VOCs) below grade. The presence <br /> Of VOCs in <br /> r-r Shallow soil-gas samples indicates that the observed" compounds <br /> " <br /> p � <br /> may be either in the vadose zone <br /> near the probe and/or in .the F <br /> ground water. Twenty-two soil-gas samples were ' <br /> r� collected from <br /> the vadose zone immediately above the shallow saturated zone <br /> and <br /> j analyzed for benzene, ethylbenzene, toluene, total xylenes r <br /> rA <br /> (BETl and TPH. Samples were collected between <br /> feet below .. two and four <br /> ; <br /> grade: on and immediate) around the site <br /> Y (Plate 1) , <br /> Soil- <br /> L� gas probe holes were alt upon <br /> backfilled with sand and as ' <br /> A ;� <br /> h <br /> completion of sample collection. An interim report..discuvsing <br /> P <br /> £: I - <br /> ._...- - - <br /> the results Ofthis <br /> survey was issued .to Southland on June 28, <br /> T X, - <br /> ,,.� 1988. <br /> Li <br /> B. moil Bori*�as <br /> x: <br /> Pill - <br /> Based upon the results of the soil-gas surve soil it borings E ; <br /> were located and drilled. Barings were advanced using60 <br /> 6-inch <br />