1988-04-11_PERMIT FILE - C1981008A

• Permit No: C1981008A
• IBM Index Class Name: PERMIT FILE
• Doc Date: 4/11/1988
• Doc Name: Hydrologic Description ‎(Part 2 of 2)‎
• Section_Exhibit Name: Tab 7
• Media Type: D
• Archive: Yes

major anions and cations) occasionally analyzed for at NPDES 001. Table 7-51 presents a
statistical summary of the historic water quality data collected at NPDES 001. Figure
7-32 presents a Schoeller diagram of mean milliequivalent values for the major ions during
both seasons at NPDES Site 001.
The water type at NPDES 001 for both seasons is a calcium magnesium sulfate. From Figure
7-32, it can be seen that NPDES 001 exhibits a similar trend of higher levels of the major
ions during periods of no irrigation as seen at Sites SW-N7 and SW-N6.
During the irrigation season, pH averages 7.52 at NPDES 001 ranging from 6.0 up to 8.6.
Between irrigation periods, the mean pH is 7.62 and ranges between 6.5 and 8.4.
The mean TDS concentration determined for NPDES 001 during the irrigation season is 2,095
mg/l. The range in TDS for the irrigation season falls between 995 mg/l and 3,470 mg/l.
In between irrigation seasons, TDS averages 2,963 mg/l, and ranges from 892 mg/l up to
3,650 mg/l.
Mean TSS, Fe and Fe all increase slightly at NPDES 001 between periods of irrigation.
During the irrigation season, average concentrations of TSS, FeT and FeD are 8.0 mg/l, .26
mg/l and .04 mg/l , respectively. For the periods of no irrigation, TSS, Fe and Fe
average 9.0 mg/l , .29 mg/l and .05 mg/l , respectively. Total manganese (Mn T) averages
higher concentrations (.17 mg/1) for the months between irrigation seasons in comparison
to the mean MnT typically exhibited at NPDES 001 during the irrigation period (.11 mg/1).
NPDES 006 - Water Quality. The NPDES 006 outfall is located on the lower end of the East
Return Ditch near the eastern boundary of the Nucla Mine (see Exhibit 7-1). Water quality
has been routinely monitored at this site as outlined and required by the Nucla NPDES
Permit (No. CO-0000213, see Appendix 7-6) since December of 1982. Appendix 7-7 contains
water quality data collected at NPDES 006 (including additional parameters occasionally
analyzed) since 1982. A trilinear plot of the distribution of major ions
for both seasons at this site is contained in Appendix 7-8. Table 7-52 presents a
statistical summary of the historic water quality data collected at NPDES 006. Figure
7-33 is a Schoeller diagram of mean milliequivalent values for the major ions during both
seasons at NPDES Site 006.
Between irrigation periods, NPDES 006 exhibits a magnesium calcium sulfate water type.
7-156 Revised 04/11/88