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Stream flow measurements and the corresponding stream depth (derived from the pressure
transducer reading) at the time of each measurement were recorded for each gauging station.
The discharge vs. depth data were plotted and a curve was fit to the data using the Trendline
feature in Microsoft Excel, including a mathematical equation describing the fitted curve. This
curve-fitting process was based on professional judgment. In some cases, the data were divided
into two or more ranges, and a rating curve was fitted for each range. This allowed the resulting
equation to be a simple function that more precisely fit a specific range of data points. These
equations were then used to create stream flow hydrographs by calculating a discharge for each
stream depth (also called the “stage” or gage height) recorded at a regular interval by the
transducer.
The stream gauging stations and surface water sub-basins used to calculate the rating curves,
daily stream flows, and monthly discharge charts are included in Appendix H.
5.3.1.2 Surface Water Quality
Surface water quality samples are being collected monthly at all surface water gauging station
locations (Map 5.3-1). Surface water quality samples were collected at Cook Lake and at the
inlet and outlet on Beaver Creek. The sample parameter list including laboratory data quality
objectives, are provided in Table 1 in Appendix H.
Table 3 in Appendix H presents the surface water field sampling parameters (conductivity, pH,
and temperature). The results of the baseline surface water quality sampling in 2011 and 2012
indicate generally good surface water quality, exceeding Wyoming Water Quality Standards at
some stations for aluminum, iron, manganese, nitrate, and nitrogen as noted in Table 4 in
Appendix H. Exceedances for iron and manganese were also observed in the Synthetic
Precipitation Leaching Procedure (SPLP) and Net Acid Generation (NAG) short-term leach tests
for waste rock material (Section 5.3.1.6).
5.3.1.3 Springs and Seeps Water Quality
Spring and seep surveys within the Project Area were sampled annually in 2011 and 2012. The
surveys include elevation, surveyed location coordinates, and collection of samples. Map 5.3-2
shows the location of the springs and seeps. Table 5 in Appendix H indicates the coordinates of
the springs and seeps.
Water samples were collected and analyzed for the water quality parameters listed in Table 2 in
Appendix H. Field water quality parameters (turbidity, pH, specific conductivity, and
temperature) were obtained with a water quality probe at the time of sample collection. Field
parameter results are shown in Table 6 in Appendix H.
There were 86 samples collected at the springs and seeps associated with the Bull Hill Mine, 27
of which showed one or more exceedances of the Wyoming Water Quality Standards. The
results of the 2011 and 2012 spring and seep water quality sampling indicate generally good
water quality but exceeding Wyoming Water Quality Standards at some of the locations for
aluminum, iron, manganese, and radon-222 as noted in Table 7 in Appendix H.
5.3.1.4 Groundwater Quality
RER completed the installation of nine groundwater monitoring wells during 2011. This included
three bedrock wells (MW-01, MW-04, and MW-05) which were completed to depths from 63 to
270 feet below ground surface (bgs). Six alluvial wells (MW-07, MW-08, MW-09, MW-10, MW-
11, and MW-14) were also installed in 2011. In late summer 2012, RER installed an additional
12 groundwater monitoring wells and RER installed an additional 22 groundwater monitoring
wells and converted 6 exploration drill sites to 7 groundwater monitoring wells in 2013 (see Map
5.3-3). The monitoring program also included monitoring of existing wells (see Map 5.3-4).
