PERMFILE115166

• Permit No: C1981008A
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Doc Name: pages 7-1 to 7-49
• Section_Exhibit Name: NH1 TAB 7 HYDROLOGIC DESCRIPTION
• Media Type: D
• Archive: Yes

• 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 wall 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/1 and 4,272 mg/1, 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 CW-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 CW -N9.
.. In comparing spring chemistry versus fall chemistry,
di
m and TDS l
vels t
in th
tall
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d to d alkalinity, bicarbonate, magnesium,
ari
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• n c
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chemistry, these same parameters al 1
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-B. The maximum iron value exceeds the Colorado Water Ouality Control
Commission (CWOCC) 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 (CW-N4 and CW-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 (CW-N4 and GW-N4R) exhibit a magnesium sulfate water type
7-31 Revised 04/11/88