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1 <br />' November 10, 1992 <br /> Job No R92024 <br /> Page 2 <br /> Soil sample analytical results collected from borings B-1 and MW-4 at five-foot intervals to a depth <br /> of 75 feet, are summarized in Table 1 Analytical results indicate chemical concentrations of TPH- <br />' G ranging from 3800 milligrams per kilogram (mg/kg) at a depth of 15 feet in MW-4 and 1400 <br /> mg/kg at 10 feet and 20 feet in B-1, to "None Detected" (ND) at a depth of 70 feet in both borings <br />' Concentrations of TPH•D ranged from 130,000 mg/kg at a depth -of 15 feet in MW-4 and 23,000 <br /> mg/kg at depths of 10 feet and 15 feet in B-1 to ND at depth of 75 feet 1n both bonngs <br /> Concentrations of Volatile Halocarbons were ND in both borings; concentrations of Volatile <br />' Aromatics ranged from 10 mg/kg of ethylbenzene, 2mg/kg toluene, 54 mg/kg xylenes at a depth <br /> of 15 feet to ND in MW-4 and to 4 mg/kg ethylbenzene and 12 mg/kg at a depth of 30 feet in B-1 <br /> Toluene was ND in boring B-1 <br /> tAnalytical results for the groundwater sample collected from MW-4 are summarized in Table 2 <br /> The results indicate "None Detected" concentrations of TPH-G, TPH-D, and Volatile Halocarbons <br />' and Aromatics with the exception of 0 6 micrograms per liter (µg/L) of xylene <br /> Laboratory Data Reports,Cham-of-Custody and Request for Analysis documentation are presented <br /> in Appendix B <br />' Conclusions <br /> Based on the findings of this soil and groundwater assessment, RS concludes the following: <br />' o TPH-D constituents have significantly impacted soil in the vicinity of the former tank <br /> emplacement TPH-G concentrations detected in the soil samples are indicative of <br /> the lighter fractions of diesel, which are stripped from the diesel during the sample <br /> preparation method for TPH-G The low to ND concentrations of volatile aromatics <br /> also indicate that the petroleum hydrocarbon contamination source was primarily <br />' diesel <br /> o Volatile halocarbon concentrations were ND in both soil and groundwater samples <br />' collected during this investigation The data indicate that chlorinated solvents have <br /> not been released in the vicinity of the former tank emplacement. <br /> o Vertical migration of petroleum hydrocarbons has occurred beneath the former fuel <br /> tanks. <br />' o In boring B-1, petroleum hydrocarbon concentrations extend vertically zrn the <br /> unsaturated zone to a depth of 70 feet and attenuate with depth Elevated <br />' REM E DIATION <br /> SERVICES INC <br />