2017-06-26_HYDROLOGY - M1980244

• Permit No: M1980244
• IBM Index Class Name: Hydrology
• Doc Date: 6/26/2017
• Doc Name: Demonstration of Compliance with WQCC Regulation No 41
• From: Newmont
• To: DRMS
• Email Name: TC1
• Media Type: D
• Archive: No

5.5 Wilson Creek
The Wilson Creek groundwater monitoring wells (WCMW 3-134 and WCMW 6-234) are located on
Bateman Creek, a tributary to Wilson Creek. An east-west trending ridge of Precambrian rock separates
the head of Bateman Creek from Arequa Gulch. The only constituent in the Wilson Creek monitoring
wells that exceeds domestic well standards is manganese in WCMW 6-234 (early samples from WCMW
3-134 exceeded the domestic well standard for manganese, but since sometime between March 1999
and March 2004, a period in which no manganese results were obtained, the concentration has remained
below 0.02 mg/L).
Sulfate data for the Wilson Creek monitoring wells are shown in Figure 16. Included in Figure 16 are the
precipitation data, totaled between sampling events, from the Rigi meteorological station. Third order
polynomial trends have been fit to the precipitation and sulfate data. It is readily apparent that
precipitation has a strong positive correlation with manganese in WCMW 3-134, and a moderately
positive correlation with manganese in WCMW 6-234. The overall trend is for slightly increasing sulfate
concentration in both wells, but the concentrations are significantly below the domestic well standard of
250 mg/L.
- --- ----
80 ._. _. __ _ - 16
70 _-__. _-__..__ ___-__- __-__ -_._- _____-_ ._._ __ 14
60 12
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E
-
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1
0
30 6
20 4
-
10
2
m m q y g n m m o M e v m n
.. .. .. ..
WCMW 3-134 -.-WCMW 6-234 Precip —Poly.(WCMW 3-134) —Poly.(WCMW 6-234) Poly.(Precp)
Figure 16: Sulfate and precipitation data for Wilson Creek monitoring wells. Third order polynomial trend lines
have been added to aid in identification of correlations.
Manganese data are plotted with precipitation, totaled between sampling events, in Figure 17. There is a
reasonably strong positive correlation between precipitation and manganese in both wells. The
manganese concentration in WCMW 6-234 is above the domestic well standard of 0.05 mg/L, whereas
manganese concentration is significantly less than the standard in WCMW 3-134. The trend for
manganese in both wells appears to be essentially unchanging.
Zinc has not been quantified in the Wilson Creek wells since early 1997. During the period that zinc was
measured, its geometric mean concentration was 0.007 mg/L in WCMW 3-134, and 0.012 mg/L in
WCMW 6-234, several orders of magnitude less than the domestic well standard. The lack of zinc above
the detection limit (since 1997) could be real, or it may be a function of analytical methodology. No time
series plot of zinc in Wilson Creek is included in the present report.