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�z <br /> s � <br /> 5.0 CONCLUSIONS R C 4 11 <br /> 5.1 CONCLUSIONS <br /> Tha soil gas survey conducted at the Holt Brothers Tractor Company <br /> facility indicated evidence of benzene, toluene, and xylene (BTX) in the <br /> soil vapors beneath the facility. The concentration contour plots (Figures <br /> 3,4 and 5) represent the constituent detections in *:he vadoso zene. and do <br /> not directly correlate to ground water constituent concentrarious and plume <br /> location. Subsurface conditions such as soil matrix, homogeneity, <br /> heterogeneity, and soil moisture affect the transport and distribution of <br /> the vapors. In add:tion, the constituant detections upon which the <br /> :jncentration contours are approximated were taken from various depths <br /> ra»ging from 6 to 15 feat due to dense soils in some locations. The <br /> detectable results, however, are an indication of BTX compounds in the <br /> ground water and suggest the location of the constituent plume. <br /> Finally, the results from the soil gas survey :nd;.eate the presence of <br /> several unknown compounds. These compounds could be solvents as evidenced <br /> in ground water samples taken during the Phase I Site Inveacigation. <br /> 5.2 RECOt94ENDATIONS <br /> Based on the results of the soil gas survey, we recommend that 2 to 3 <br /> additional monitoring cells be installed at the facility; one near the <br /> southwest corner of the shop; one near the southwest corner of the loading <br /> ramp (to later be used as a recovery well); and a third wall further vest of <br /> the southwest shop corner. The exact location of the additional monitoring <br /> wells aad the well construction details should he fully specified in the <br /> v Phase II Site Investigation Work Plan. <br /> __ •opo- <br /> Respectfully submitted, <br /> DAMES h MOORE <br /> Burton Gilpin <br /> Staff Geologist <br /> ct ~ <br /> Laslia Dumas <br /> Project Engineer <br /> — " LD01.046 S <br /> �f: <br />