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Elevated levels of fluoride may be attributed to natural (i.e., not <br />mining related) conditions, since elevated levels for those parameters <br />are not found in PSCM spoil wells. However, elevated values of fluoride <br />were found in many wells before, as well as upgradient of, mining. In <br />the case of fluoride, the wells that have elevated levels this year have <br />historically displayed high levels. All three wells are also unique in <br />displaying a sodium bicarbonate type water with relatively high pH <br />values. It is suspected that the high fluoride values are related to <br />this type of water chemistry (Hem, 1989, pg. 121). All wells exist <br />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 due to naturally <br />occurring geochemical conditions, especially in alluvial material (Hem, <br />1989, pgs. 86-89). Manganese exceedances have occurred at all alluvial <br />wells, including the one Grassy Creek alluvial well upstream of the PSCM <br />(Well 71) and one Wadge coal well located just west of NPDES Pond <br />002(Well 17). This standard is used to protect crops grown in soils with <br />a pH value lower than 6.0. In January 2008, CDPHE revised their ground <br />water agricultural standard to reflect this pH qualifier. In soils with <br />a higher pH (as are found in the PSCM region), a more appropriate <br />standard would be 10 mg/l (EPA, 1976). This year, none of the PSCM <br />alluvial wells displayed a value higher than 2.14 mg/1, and no spoil <br />wells displayed a value higher than 6.93 mg/l. <br />Ground Water Points of Compliance <br />Ground Water Points of Compliance (GWPOC) have been established for the <br />PSCM (PSCM PAP page 2.04-103, Vol. 1). Attachment 7-3 of the Seneca II <br />PAP provides the details of how the standards were established. The <br />ground water standards for Grassy Creek Alluvial Well SGAL70 are <br />provided in this AHR on Table 7. No exceedances of those standards were <br />observed on samples collected from SGAL70 this year. <br />Ground Water Quality Summary. <br />TDS values at five of the 15 wells sampled this year displayed <br />increasing TDS trends. TDS trends at the remaining wells were either <br />9 <br />