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4� <br /> Table 2 Groundwater Chemical Data, con't <br /> Well Date TPHG Benzene Toluene Ethylbenzene Xylene Fuel Ox <br /> NoSampled ----------------------------- u g/l ------------------------------- <br /> MW-7 8120197 NO -- ND-- ND------- -- NO NO ND <br /> MW-7 12/12/97 NO NO NO NO NO NO <br /> MW-7 3131198 NO NO NO NO NO NO <br /> MW-7 6130198 NO NO NO NO NO NO <br /> MW-8 8120/97 NO NO ND NO NO NO <br /> MW-8 12/12/97 NO NO NO NO NO NO <br /> MW-8 3/31198 NO NO NO NO NO NO <br /> MW-8 6130198 NO NO NO NO NO NO <br /> M W-9 8/20/97 14,000 12 4 0 14 24 NO <br /> MW-9 12/12/97 260 11 15 37 12 NO <br /> MW-9 3/31/98 15,000 1,700 470 890 1,500 NO <br /> MW-9 6/30198 29,000 1,600 490 1,400 2,900 NO <br /> Blank 3131/98 NO NO NO NO NO NO <br /> NO - None detected NA - Not Analyzed ug/l - micrograms per liter <br /> Fuel Ox - Fuel Oxygenates by Method 8260 from Dec , 1997 forward <br /> ' - Quantified as MTBE <br /> Discussion <br /> Groundwater movement is north-northwesterly at a low flow gradient and the flow direction is <br /> consistent with historically observed trends A large groundwater mound has appeared at M W- <br /> 9 This well is very near a large agricultural line and strongly suggests leakage from either <br /> that pipeline or another in the near vicinity <br /> Concentrations of TPHG were observed in the Wells MW-1, MW-2, MW-3, and MW- were <br /> slightly lower than the previous sampling round Concentrations were high at MW-9 and <br /> coincide with the appearance of a large groundwater mound, and appear to have mobilized the <br /> absorbed contaminants in the vicinity of MW-9 MTBE was not observed in any well <br /> Fluctuations of observed contaminant concentrations are attributed to winter precipitation <br /> recharge and rasing water levels which allow more desorption of residual contaminants In our <br /> opinion, a degraded fuel and fluctuating concentrations of contaminants and are anticipated to <br /> continue to show an overall declining trend <br /> The occurrence of contaminants in MW-6 is currently attributed to an offs1te source <br /> (presumably from south across East Eleventh Street) since MW-6 is upgradient of the known <br /> on-site contaminant source <br /> J <br /> Page 5 <br />