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Ms Vicki McCartney Project No 880040 1A 02010000 <br /> June 10, 2005 <br />' Page 3 <br /> ethylbenzene, xylenes (BTEX), 1,2-dibromo ethane (EDB), 1,2-dichloroethane <br /> (1,2-DCA), and for five gasoline oxygenates MTBE, di-isopropyl ether (DIPE), ethyl <br /> tert-butyl ether (ETBE), tert-amyl methyl ether (TAME), and tert-butyl alcohol (TBA) <br /> using U S Environmental Protection Agency (EPA) Methods 8015GRO/8021 B <br /> a and 8260B Field and laboratory procedures are presented in Attachment A Certified <br /> analytical reports, chain-of-custody documentation, and field data sheets are presented in <br /> Attachment B <br /> Second Quarter Groundwater Monitoring Results <br />' Groundwater elevations measured at the site were an average of 1 36 feet higher than <br /> measured in the previous sampling event of January 17, 2005 nnGroundwater flow was ? <br /> ar tlO <br /> inferred to be to the northeast at an average gradient of 0 0018, which was consistent <br /> with previous sampling events Groundwater elevation data are presented in Table 1 <br /> A groundwater elevation contour map based on the April 18, 2005 data is shown on <br /> Figure 1 <br /> i <br /> TPHg range hydrocarbons were reported in samples from wells MW-1, MW-2, MW-3, <br /> and MW-4 at concentrations of 750, 65, 120, and 95 micrograms per liter (pg/L), <br />' respectively Benzene was reported in the sample from well MW-1 at a concentration of <br /> 71 pg/L MTBE was reported in samples from all the wells at concentrations ranging <br />' from 10 pg/L (well MW-1), to 930 pg/L (well MW-4) TBA was reported in samples <br /> from all wells except MW-4 at concentrations ranging from 170 gg/L (well MW-2), to <br /> 2,600 pg/L (well MW-1) Groundwater analytical data are presented in Table 1 TPHg, <br /> benzene, and MTBE concentrations on April 18, 2005, are shown on Figure 2 <br /> r <br /> DISCUSSION <br /> Groundwater levels were over one foot higher than in the January 2005 sampling event <br /> Groundwater analytical data were generally consistent with historical data <br /> Shaw recommends continued monitoring of the site groundwater monitoring wells to <br /> further evaluate the dissolved hydrocarbon plume at the site <br /> SHAW ENVIRONMENTAL,INC <br /> N\sac DP120051Prj1880\880040 1A 5 a doe <br />