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elevated levels this year, have historically displayed high levels. All <br />three wells are also unique in displaying a sodium bicarbonate type <br />water with relatively high pH values. It is suspected that the high <br />fluoride values are related to this type of water chemistry (Hem, 1989, <br />pg. 121). All wells exist within the PSCM permit boundary. <br />The high levels of iron displayed in Alluvial Well 71 may be the result <br />of organic matter and plant debris present in the alluvium (Hem, 1989, <br />pg. 77). This well has historically exhibited high iron values (seven <br />out of forty - seven) and exists within the PSCM permit boundary. <br />High manganese values may, in part, be due to recharge from the spoil <br />aquifer, although high values are often common, especially in alluvial <br />material (Hem, 1989, pgs. 86 -89). Manganese exceedances have occurred at <br />all alluvial wells, including the one Grassy Creek alluvial well <br />upstream of Seneca II (Well 71). This standard is used to protect crops <br />grown in soils with a pH value lower than 6.0. In January 2008, CDPHE <br />revised their ground water agricultural standard to reflect this pH <br />qualifier. In soils with a higher pH (as are found in the PSCM region), <br />a more appropriate standard would be 10 mg /1 (EPA, 1976). This year, <br />none of the PSCM alluvial wells displayed a value higher than 3 mg /1, <br />and no spoil wells displayed a value higher than 2 mg /1. <br />Finally, water quality analyses performed on two samples obtained at the <br />PSCM shop well (CTC87) for this year were compared against both human <br />health (mandatory) and secondary (i.e., recommended but not mandatory) <br />drinking water standards developed for ground water by the CDPHE. The <br />human health standard for cadmium (5 ug /l) was exceeded in the first <br />sample only, with a value of 7 ug /1. The CDPHE secondary standards for <br />iron and pH (0.3 mg /1 and pH 6.5 -8.5) were exceeded in the first sample <br />only, with values of 0.82 mg /1 iron and a pH of 8.82. The first sample <br />was collected in May directly at the wellhead (i.e., prior to <br />treatment). The second sample, collected in September (and after <br />treatment) did not exceed any drinking water standards. Bottled water is <br />normally consumed at the PSCM. <br />7 <br />