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r <br />u <br />C <br />4.2 Groundwater Sampling and Analytical Results <br />Samples from temporary wells MW -10 and MW -11 were collected on October 13, 2011. <br />As a result of slow movement of groundwater at temporary well MW -9, sampling of this <br />well was conducted on October 19, 2011. Groundwater samples were collected using a <br />decontaminated, %2 -inch stainless steel or 4 -inch -diameter disposable polyethylene <br />bailers. Groundwater was transferred from the disposable bailer into laboratory - <br />provided 40 -milliliter glass containers (VOAs) with hydrochloric acid preservative. <br />Samples and a travel blank were transferred to the laboratory courier under strict chain - <br />of -custody protocols, and were analyzed for volatile organic compounds (VOCs) <br />according to EPA Method 8260B by BC Laboraories, Inc. (BC) of Bakersfield, California. <br />Samples from the temporary wells yielded the following results: <br />No VOCs were detected in the travel blank or laboratory method blank. <br />Isoconcentration contours (Figures 2 through 4) were developed to assess the <br />distribution of VOCs among the existing shallow groundwater monitoring network <br />(using the third quarter [Summer] 2011 data) and the temporary monitoring wells. <br />To verify these finding, the County directed GLA to collect a second set of samples. <br />Groundwater elevations were measured, and groundwater samples were collected from <br />each of the three temporary wells on November 2, 2011. The results of the second tests <br />confirmed the first, as follows: <br />Well ID <br />VOC Concentrations From Samples Taken October 19, 2011(Mg/L) <br />VOC Concentrations from samples taken November 2, 2011(©g/L) <br />DCDFM PCE TCFM Total VOC <br />Well ID <br />Dichlorodifluoromethane <br />(DCDFM) <br />Tetrachloroethene <br />(PCE) <br />Trichlorofluoromethane <br />(TCFM) <br />Total VOC <br />MW -9 <br />2.1 <br />0.32 (trace) <br />0.61 <br />3.03 <br />MW -10 <br />0.21 (trace) <br />0.66 <br />0.22 (trace) <br />1.09 <br />MW -11 <br />1 2.8 <br />1.6 <br />0.16 (trace) <br />4.56 <br />No VOCs were detected in the travel blank or laboratory method blank. <br />Isoconcentration contours (Figures 2 through 4) were developed to assess the <br />distribution of VOCs among the existing shallow groundwater monitoring network <br />(using the third quarter [Summer] 2011 data) and the temporary monitoring wells. <br />To verify these finding, the County directed GLA to collect a second set of samples. <br />Groundwater elevations were measured, and groundwater samples were collected from <br />each of the three temporary wells on November 2, 2011. The results of the second tests <br />confirmed the first, as follows: <br />Well ID <br />Groundwater <br />Elevation (ft) <br />VOC Concentrations from samples taken November 2, 2011(©g/L) <br />DCDFM PCE TCFM Total VOC <br />MW -9 <br />230.77 <br />2.6 <br />0.66 <br />1.5 <br />4.76 <br />MW -10 <br />220.06 <br />0.52 <br />0.88 <br />0.40 (trace) <br />1.8 <br />MW -11 <br />216.57 <br />2.9 <br />1.3 <br />0.15 (trace) <br />4.35 <br />No VOCs were detected in the travel blank or laboratory method blank. These results <br />verify the preliminary sample results and suggest a northeasterly migration of VOCs <br />from the CHSL. Laboratory data and chain -of -custody documentation for the <br />preliminary and verification sample sets are provided in Attachment 2. <br />Conclusion <br />VOCs consistent with those found in monitoring well MW -5 were found in the <br />temporary wells, and appear to generally migrate outward from the northern corner of <br />Well Completion Reporte-am 0 'C Page ■ 4 <br />Corral Hollow Sanitary Landfill Ass o c I ere a <br />December 15, 2011 <br />