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Mr. Gabriel Karo Project 939-01.09 <br /> April 9, 1992 <br /> Page 4 <br /> AirSWAT Analysis <br /> The results from analysis of the atmospheric gases in the three landfill gas <br /> samples are summarized in attachment 2 and the analytical reports are <br /> contained in attachment 3. The laboratory methane data correlated well <br /> with the methane concentrations measured in the field at the time of <br /> sampling and support the integrity of the sampling procedures. <br /> The analytical results for the EPA TO-14 analysis for AirSWAT <br /> compounds in the three landfill gas samples are also contained in <br /> attachments 2 and 3. The concentrations of total AirSWAT compounds in <br /> the 3 samples ranged from 1.7 to 8.2 ppmv. The average of the 3 sample <br /> concentrations of 4.4 ppmv is approximately 25 percent of the average <br /> (17.6 ppm) for the 5 shallow refuse as well samples analyzed during the <br /> Calderon AirSWAT testing in 1988. A summary of the 1988 AirSWAT <br /> concentrations is contained in attachment 4. Although the same five <br /> compounds (vinyl chloride, methylene chloride, benzene, trichloroethene, <br /> and tetrachloroethene) were prominent, the distribution of relative <br /> concentrations for individual compounds varied significantly between the <br /> two sample sets. Especially significant was the relative concentration of <br /> methylene chloride, which averaged 81 percent of the total in the 1988 <br /> Calderon samples and only 11 percent of the total of the current samples. <br /> Methylene chloride was not detected in two of the current samples. <br /> Factors contributing to variability in the concentration of total compounds <br /> include decreases due to prior emissions from the older, deeper refuse, <br /> biological attenuation during transmission through refuse or soil, the <br /> 4-year time lapse between samplings, and the general heterogeneity of <br /> waste placement. <br /> Structure Monitoring <br /> EMCON monitored 45 housing units with the FID for methane intrusion, <br /> including the 25 units closest to the landfill property line. The 20 additional <br /> monitored units were distributed evenly over the property areas further <br /> from the landfill. The housing operations office building was also <br /> monitored. No methane was detected in any monitored structure. <br /> PJ9 9390109.EOW <br />