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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 0.36 mg/1, and no spoil <br />wells displayed a value higher than 3.42 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.l). 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 excursions occurred in 2017. <br />However, the standard for cadmium is 5 ug/l and the May concentration <br />exhibited a <10.0 ug/l value. <br />Ground Water Quality Summary. <br />TDS values at three of the seven wells sampled this year displayed <br />increasing TDS trends. TDS trends at the remaining wells were either <br />stable or decreasing. CDPHE agricultural ground water standards for pH, <br />fluoride and manganese were exceeded at certain monitoring wells. There <br />were no GWPOC exceedances in 2017. In the area surrounding the PSCM, <br />ground water is not being pumped for irrigation or livestock watering <br />purposes, nor has the CDPHE classified any aquifer in this region for <br />any use. The above discussion is provided only to serve as a comparative <br />basis to judge ground water quality. Domestic wells that provide <br />drinking water for mine employees or residents are not from aquifers <br />impacted by mining. <br />M <br />