2016-09-26_REPORT - C1992081 - Laserfiche WebLink

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Well HGDAL4 is upgradient of the Loadout. It was drilled in 2005. It displays an increasing TDS trend, with the peak TES value occurring in May 2015. This year's ground water quality was compared against CDPHE ground water agricultural use standards (CDPHE, Reg. 41, 2008). Results of those comparisons are presented in Table 5. Both wells exceeded the boron standard (750 ug/1) in September. According to the CDPHE, the 750 ug/l standard is set for sensitive crops (CDOH, Reg. 41, 2008), and that the limit otherwise is 5000 ug/l. None of these sensitive plant species are grown commercially in this area. This year, neither of the Loadout wells displayed a boron value higher than 1100 mg/1. In September the cadmium Method Detection Limit (MDL) was 50 ug/1. All test values this year were less than the MDL. In September the lead Method Detection Limit (MDL) was 300 ug/l. All test values this year were less than the MDL. Both wells exceeded the manganese standard (0.2 mg/1) in both May and September. It should be noted that, while the CDPHE uses a manganese standard of 0.2 mg/l, the EPA states that this standard is used to protect crops grown in soils with a pH value lower than 6.0. In January 2008, CDPHE revised their ground water agricultural standard to reflect this pH qualifier. In soils with a higher pH (as are found in the HGT region), a more appropriate standard would be 10 mg/l (EPA. 1976. "Quality Criteria for Water"). This year, neither of the Loadout wells displayed a manganese value higher than 3 mg/l. In a letter dated June 5, 2008, Tom Kaldenbach of the CDRMS stated that "Groundwater points of compliance are unwarranted at the Hayden Gulch Loadout...". He further concluded that "... any leachate originating at the loadout would likely be of better quality than native groundwater in the Lewis Shale which has high concentrations of dissolved solids." This