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i 8 E The only other constituents to exceed MCLs were iron and manganese in the Koster well (only i once), South Tracy 91 well (only twice), and the two Brown's wells. It is important to note that I l none of these four wells is a domestic well; the Koster well is used for irrigation and the South i Tracy #1 and Brown's wells are for industrial uses. The analytical results from these wells 'I indicated that iron and manganese concentrations were typically below detection limits and were E intermittently at or above the respective MCLS possibly due to higher turbidity in those samples. In the case of the Brown's wells, samples have exceeded the MCLs for iron and manganese more i often than other wells, and this has continued to be the case during 1997. The Brown's #1 well is a standby well that is used very infrequently and it would be expected that samples from this iwell be more turbid, despite the ample amount of purging that has been performed prior to sampling the well (upwards of 10 casing volumes). The Brown's New well has been used less frequently during 1997 due to operational problems and has shown similar elevated iron and manganese concentrations during that time. Support for the assumption that the elevated iron and manganese concentrations are derived from fine sediment in turbid samples is provided by field observations during sample collection. During the periods when iron and manganese I i concentrations were elevated, the sample was observed to be turbid; alternately, during the periods when these constituents were very low or non-detectable, the well was or had been pumping already and sample turbidity was very low. Total coliform bacteria were absent from the domestic wells during 1994 through early 1998 with the exception of the Faulkner well during the fall of 1994. Samples collected in October and from retesting in November of that year showed coliform bacteria were present, but none were fecal coliform. All testing subsequent to treating (disinfecting) the well indicated the coliform bacteria have been absent since January 1995. + i ® LL1F--SDORFF� 5 SCALMANINI C GN! 5 Li L r I C1 E nl G 1 11 E E P ,-3 V