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Mr Martin Harris <br /> Page 6 of 7 <br /> Groundwater Analytical Results <br /> Groundwater samples were analyzed for the presence of TPHg, BTEX, and oxygenated gasoline <br /> additives including 1 2-DCA and EDB using EPA methods 8015B, 8021B, and 8260B, <br /> respectively <br /> TPHg was detected in well MW7 at a concentration of 69 µg/L No TPHg was detected in any <br /> other site well <br /> Ethylbenzene was detected only in well MW1, at a concentration of 0 9 µg/L No BTEX <br /> constituents were detected in any other site well in March 2005 <br /> MTBE was detected in wells MW1, MW2, MW3, MW5, MW9, and MW10 at concentrations of <br /> 1 5 µg/L, 12 µg/L, 4 5 pg/L, 5 4 µg/L, 1 6 pg/L, and 0 7 µg/L, respectively No MTBE was <br /> detected above the method detection limit (MDL) of 0 5 pg/L in wells MW4, MW6, MW7, <br /> MW8, or MW11D No other oxygenated gasoline additives or lead scavengers were detected in <br /> any site well Analytical results are summarized in Table 3 The estimated extent of dissolved <br /> MTBE contamination based upon the most recent analytical results is presented on Figure 4 <br /> Attachment G contains the laboratory report and chain of custody documentation Charts <br /> showing contaminant concentration trends are included in Attachment H <br /> i <br /> SUMMARY AND CONCLUSIONS <br /> Shallow groundwater beneath the site rose an average of 1 04 feet between December 10, 2004 <br /> and March 28, 2005 Groundwater on March 28, 2005 generally flowed to the northwest at a <br /> relatively flat gradient of approximately 5 ft/mile <br /> TPHg was detected only in well MW7, at 69 µg/L No benzene, toluene, or xylenes were <br /> detected in any site well and ethylbenzene was detected only in well MW 1, at 0 9 µg/L MTBE <br /> was detected in wells MW1, MW2, MW3, MWS, MW9, and MW10 at levels ranging from 0 7 <br /> to 5 4 µg/L No well contained MTBE at concentrations exceeding the primary Maximum <br /> Contaminant Level (MCL) of 13 µg/L, and only well MW5 contained MTBE at concentrations <br /> exceeded the secondary MCL of 5 0 pg/L <br /> Based upon the most recent analytical results, the dissolved MTBE plume at the site covers an area <br /> of approximately 9,200 square feet (Figure 4) and is well within the property boundaries No <br /> MTBE was detected in the deeper zone monitoring well (MW 11 D) Assuming a saturated <br /> thickness of approximately 15 feet, based upon boring logs, Iess than 1 teaspoon of MTBE remains <br /> in the plume <br /> G1GROUNDZLNTuffBoy\ReportslQMR`200513 QM2005 doc <br />