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• 4.0 RESULTS 4.1 Stratigraphy The boring logs in Appendix A show the strata that were penetrated by the borings Figure 3 is a cross section illustrating this sequence of strata, which is essentially the same as had been encountered in VM-1 From the surface to a depth of approximately 30 feet, the uppermost stratum coarsens downward from clay or silty clay to very coarse-grained sand In the upper part, the color is brown, but downward the color changes to grayish brown and gray, due to a decrease in oxidation and weathering Moisture content increases downward from dry to slightly damp Below 30 feet, the dominant lithology is silt, which is interbedded with thinner layers of fine-grained sand and silty clay Variable amounts of iron-oxide staining result in mottled gray, orange, and brown colors to a depth of 60 feet No samples were collected below 60 feet, but the previously collected samples from VM-1 were dark to very dark gray, indicating that the material has been continually below the groundwater table and is not oxidized r 4.2 Field Evidence of Contamination No hydrocarbon odors were noticed in soil samples collected from 1HP-2 or HP-3/VM-3 Strong gasoline odors and PID readings ranging from 265 ppm to over 4000 ppm were noted in samples from VM-2 at 5, 10, 15, and 20, feet PID readings and odors decreased below 20 feet, although readings in excess of 200 ppm were still present at 45 feet A moderate gasoline odor was noticed during the collection of the groundwater samples from VM-1 and VM-2 4.3 Laboratory Results 4 3.1 Soil Samples The selected samples were analyzed for Total Petroleum Hydrocarbons in the gasoline and diesel ranges (TPH-g and TPH-d), for benzene, toluene, ethylbenzene, and xylene (BTEX), and for methyl tertiary butyl ether(MTBE) Table I shows the laboratory results for all soil samples collected to date No contaminants were detected in the two soil samples from HP-2 or the three samples from HP-3 In VM-2, no contaminants were detected in the samples from 45 and 55 feet, which is in accord with field observations (see Appendix A) Of the five samples from shallower depths, gasoline and/or BTEX were detected in four, at concentrations that are lower than might have been predicted from the strong odors and PID response in the field Because the laboratory chemist also noticed the strong gasoline odors, these samples were analyzed two or in some cases three times, at decreasing methanol dilution ratios, in order to obtain precise concentrations and acceptable reporting limits Despite the strong odors and PID readings, however, laboratory instruments recorded only moderate concentrations 1 4