1988-04-11_PERMIT FILE - C1981008A (9)

Home Browse Search

water analyses performed on water sampled from this well is presented in Table 7-7. Trilinear diagrams representing analyses performed during periods of irrigation and no irrigation are presented in Appendix 7-3. The individual water quality analyses for Well GW-N9 are presented in Appendix 7-4. The well location is shown on Exhibit 7-1. The water type at Well GW-N9 is calcium magnesium sulfate during the irrigation season and magnesium calcium sulfate during periods of no irrigation. The mean TDS levels during periods of irrigation and no irrigation are 3,635 mg/l and 4,272 mg/l, respectively. Schoeller diagrams, representing mean milliequivalent values for the two above-referenced time periods, are presented on Figure 7-2 to show which ions account for the increase in TDS during periods of no irrigation. Magnesium, sodium, bicarbonate, sulfate and chloride concentrations all increase significantly when the area is not being irrigated. A range in pH values from 6.8 to 7.7 has been measured at Well GW-N9. The mean pH value for this well as of January 1, 1988 is 6.8. There is a limited amount of seasonal variability in the water chemistry of Well GW-N9. In comparing spring chemistry versus fall chemistry, alkalinity, bicarbonate, magnesium, sodium and TDS levels tend to decrease in the fall . In comparing summer versus winter chemistry, these same parameters all tend to increase in the winter. A summary of the ranges in concentration for trace elements sampled at Well GW-N9 are presented in Table 7-8. The maximum iron value exceeds the Colorado Water Quality Control Commission (CWQCC) agricultural standard; however, the mean iron concentration is well below the standard. The water is suitable for use as livestock drinking water (Table 7-9). Measurable trace metal concentrations at this site include boron, fluoride, iron, manganese and zinc. There are two wells (GW-N4 and GW-N4R) monitoring the Dakota coal aquifer at the Nucla mining area. Statistical summaries of the water analyses performed on water sampled from these wells are presented in Tables 7-10 and 7-11. Trilinear diagrams representing analyses performed during periods of irrigation and no irrigation are presented in Appendix 7-3. The individual water quality analyses for the coal aquifer wells are presented in Appendix 7-4. The well locations are shown on Exhibit 7-1 . The two coal monitoring wells (GW-N4 and GW-N4R) exhibit a magnesium sulfate water type 7-31 Revised 04/11/88