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Parameter # of Wells / # of Excursions <br />pH (CDOH, irrigation) 2/3 <br />fluoride (CDOH, irrigation) 4/6 <br />iron (CDOH, irrigation) 4/5 <br />manganese (CDOH, irrigation) 14/26 <br />In addition, a total of five samples (from four wells) had cadmium <br />values that were less than an elevated detection limit (20 ug/1 vs. a <br />normal detection limit of 3 ug/1), which was higher than the CDOH <br />standard of 10 ug/1. Likewise, the same five samples had lead values <br />that were less than an elevated detection limit (200 ug/1 vs. a normal <br />detection limit of 20 ug/1), which was higher than the CDOH standard of <br />100 ug/1. The cause of these elevated detection limits was a decision <br />by the laboratory to dilute the samples prior to analyses in order to <br />reduce the effects o£ interferences (primarily, high salinity). <br />Elevated levels of iron and fluoride may be attributed to natural (i.e., <br />not mining related) conditions, since elevated levels for those <br />parameters are not found in Seneca II spoil wells. In the case of <br />fluoride, three of the wells (8P1, 11 and 19) that have elevated levels <br />have historically displayed high levels. Those wells are also unique in <br />displaying a sodium bicarbonate type water; with almost no calcium, <br />magnesium, or sulfates; and with relatively high pH values. It is <br />suspected that the high fluoride values are related to this type of <br />water chemistry (Hem, 1989, pg. 121). The high fluoride value observed <br />at SLGAL6 in October 2001 is probably an anomaly. Fluoride values <br />before and after this sample are an order of magnitude less. All four <br />wells exist within the Seneca II permit boundary. <br />In the case of iron, the one Wadge Underburden well (7) exhibiting high <br />levels may have high than usual concentrations of iron pyrite in the <br />rock. The high levels of iron displayed in the three alluvial wells <br />(32, 33 and 71) may be the result of organic matter and plant debris <br />present in the alluvium (Hem, 1989, pg. 77). All these wells have <br />historically exhibited high iron values and all (except We11 71) exist <br />9 <br />