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CAMBRIA <br /> r. <br /> recommended hold time Wells MW-1, MW-3 through MW-5, MW-8 through <br /> MW-11, MW-14, and VEW-2 through VEW-4 contained benzene at concentrations <br /> ranging from 1 82 to 12,800 ppb Benzene results for well MW-10, MW-11 were <br /> generated outside of EPA recommended hold time MTBE (by EPA Method 8020) <br /> was reported in wells MW-1, MW-3 through MW-5, MW-10, and VEW-1 through <br /> VEW-4 at concentrations ranging from 5 49 to 160 ppb MTBE by EPA Method <br /> 8020 results for well MW-10 was generated outside of EPA recommended hold time <br /> MTBE (by EPA Method 8260) was detected in wells MW-1, MW-3 through MW-5, <br /> and VEW-1 through VEW-4 at concentrations ranging from 3 44 to 1,360 ppb TBA <br /> was detected in wells MW-3, MW-9, and VEW-4 at concentrations of 134, 153, 156 <br /> ppb, respectively A chemical concentration map is presented on Figure 2 <br /> • 1,2-Dibromoethane (EDB) was detected in wells MW-3 and MW-4 at concentrations <br /> of 2 04 and 2 41 ppb, respectively 1,2-Dichloroethane (1,2-DCA) was detected in <br /> well MW-4 at a concentration of 2 61 ppb Ternary amyl methyl ether (TAME) <br /> was detected in well MW-4 at a concentration of 2 82 ppb <br /> Quarterly Sampling <br /> Groundwater samples were analyzed for total purgeable hydrocarbons as gasoline (TPHg) by <br /> EPA Method 8015 (Modified), benzene, toluene, ethylbenzene, xylenes (BTEX) and methyl <br /> tertiary butyl ether (MTBE) by EPA Method 8020, and fuel oxygenates, 1,2-DCA, EDB by <br /> EPA Method 8260A <br /> Field monitoring data and chemical analytical data are presented in a summary table in <br /> Blaine's groundwater monitoring report (Appendix A) <br /> Conclusions and Recommendations <br /> Groundwater samples collected from the monitoring wells this quarter contained petroleum <br /> hydrocarbon concentrations similar to previous quarters' concentrations <br /> Vaporwells VEW-1 through VEW-4 were sampled this quarter to determine if wells MW-I, <br /> MW-4, and MW-5 are accurately monitoring water quality in this area of the site Due to a <br /> regional rise in groundwater level, the well screens for wells MW-1, MW-4, and MW-5 are <br /> slightly drown The screened intervals for VEW-1 through VEW-4 currently intercept the <br /> top of the water table The analytical data from the vapor wells closely matched the <br /> analytical data from adjacent monitoring wells This suggests that even though the <br /> 1399 2 <br />