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Groundwater quality reports for this year are presented in Appendix B. <br />Data provided include a water quality report for the 2018 water year, a <br />water level report, sampling remarks and a listing of a regression plot <br />of historic TDS data. <br />Well HGDAL3 is downgradient of the Loadout. It was drilled in 1993. It <br />displays a decreasing TDS trend; the peak TDS value occurred in 1997. <br />Well HGDAL4 is upgradient of the Loadout. It was drilled in 2005. It <br />displays an increasing TDS trend; with the peak TDS value occurring in <br />2015. <br />This year's groundwater quality was compared against CDPHE groundwater <br />agricultural use standards (CDPHE, Reg. 41, 2008). Results of those <br />comparisons are presented in Table 5. <br />Both wells exceeded the manganese standard (0.2 mg/1) in both May and <br />September. It should be noted that, while the CDPHE uses a manganese <br />standard of 0.2 mg/l, the EPA states that this standard is used to <br />protect crops grown in soils with a pH value lower than 6.0. In January <br />2008, CDPHE revised their groundwater agricultural standard to reflect <br />this pH qualifier. In soils with a higher pH (as are found in the HGT <br />region), a more appropriate standard would be 10 mg/l (EPA. 1976. <br />"Quality Criteria for Water"). This year, neither of the HGT wells <br />displayed a manganese value higher than 6 mg/l. <br />In a letter dated June 5, 2008, Tom Kaldenbach of the CDRMS stated, <br />"Groundwater points of compliance are unwarranted at the Hayden Gulch <br />Loadout...". He further concluded "... any leachate originating at the <br />loadout would likely be of better quality than native groundwater in the <br />Lewis Shale which has high concentrations of dissolved solids." This <br />letter was provided in the 2008 AHR, Figure 3 (Appendix A). Monitoring <br />conducted this year at the Loadout continues to support these <br />conclusions. <br />N. <br />