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• the CDOH ataadar8 of 100 ug/1. The cause of these elevated detection limits was <br />a derision by the laboratory to dilute the eaa~lea prior to analyses in order to <br />reduce the effects o£ interferences (primarily, high salinity). <br />Elevated levels of iron and £luorlde may be attributed to natural (i.e., not <br />mining related) conditions, since elevated levels for those parameters are not <br />£ouad is Seneca II spoil wells. is the case of fluoride, the three wells (HP1, <br />11 aa8 19) that have elevated levels have historically displayed high levels. <br />Thoea walla era also unique is displaying a sodium bicarbonate type watart with <br />almost no calcium, magnesium, or sulfates; and with relatively high DH values. <br />It is suapacted that the high fluoride values era related to this type of water <br />chemistry (Hem, 1989, pg. 121). All three wells exist within the Seneca II <br />permit boundary. <br />In the case of iron, the one Wedge vaderburdea wall (73 exhibiting high levels <br />may have high than usual coneentratioae of iron yyrite in the rock. The high <br />• levels of iron displayed in the two alluvial walls (32 and 33) may be the result <br />of orgmic matter nab pleat debris preaeat in the alluvium (Hem, 1989, Dg- 77). <br />All three walla have hiatorleally exhibited high iron values and exist within <br />the Seneca II permit boundary. <br />Tha one high mercury value observed at Well SWUBPI ie considered to ba as <br />erroneous value. This, or ao other, well at 8enace II has ever exhibited such a <br />high value. Mercury values at this well before and after this sample wars all <br />below the detection limit. <br />High sulfate values may, in part, be due to recharge from the syoil aquifer. <br />However, it moat be noted that the CDOH hoe ao ground water agricultural <br />etandar8 for sulfate. This Cali£oraia ataadard is Dreseate8 here merely Eor <br />comparative purposes, It should also be noted that the one Grassy Creek <br />alluvial well (71) upstream of Seneca SI also exhibits high sulfate values. <br /> High mangaaeee values may, in Dart, be due to recharge from the spoil aquifer, <br />• although high values <br />1989 <br />H6-89) <br />a are often common, especially is <br />O£ the fourteen wells dis <br />la <br />in alluvial material IHem, <br />hi <br />h values <br />onl <br />five <br /> . <br />, pg <br />. p <br />y <br />g g <br />y <br />, <br /> (SLGAL70, SLGAL3IA, SLGAL6, SSp62, and SWf77) are indicat ing an increasing trend. <br />9 <br />