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RER established monthly groundwater sampling for the Wyoming Water Quality parameters
(Table 1 in Appendix H). The objectives of the groundwater program are to characterize
groundwater quality within the Project Area to determine baseline conditions prior to mining, and
to detect any changes that may occur over time as the mine develops, operates, and closes.
The groundwater monitoring events are listed in Table 8 in Appendix H.
Two piezometers were installed during 2010 in the mineralized zone of the Mineable Pit (see
Map 5.3-3). The base of the temporary piezometer installations is believed to be at or within the
oxide geochemical zone of the ore deposit. In 2011, one sample was collected from each of
these sites to represent an empirical measurement of mineralized zone groundwater. Both
temporary piezometers were plugged and abandoned in accordance with Wyoming regulatory
requirements during 2011.
In addition to the groundwater monitoring wells, water quality data was obtained from existing
nearby U.S. Air Force (USAF) wells, Vista West, and Sundance municipal wells as described
below (see Map 5.3-4):
Two Air Force wells: USAF-01-SW and USAF-02-SW located down-gradient of the
Sundance PM-1 Reactor Site; these wells were installed by the Air Force to monitor the
release of fissionable reactor products following a corrective action cleanup of the radar
station (U.S. Air Force, Air Combat Command (USAF/Earthtech), 2006). These well
locations are identified on Map 5.3-3 and were sampled for the parameters listed in
Table 1 in Appendix H. The groundwater samples for these wells were obtained from
split samples taken annually by the USAF.
Two of the three municipal supply wells at the Vista West community were sampled in
2011. These wells, located south and west of the Project Area in Reuter Canyon, were
monitored to further characterize baseline water quality prior to the mine operations.
Well locations are identified on Map 5.3-4.
There are seven municipal supply wells for the Sundance community. Six of these wells
are located east of the Project Area in Cole Canyon and one is located off Warren Peak
Road, north of U.S. Highway 14. Two of the wells (SMW-01 and SMW-02) located east
of the Project Area in Cole Canyon were monitored to further characterize baseline
water quality prior to mining operations. The monitored well locations are shown on Map
5.3-4.
Field groundwater quality parameters: turbidity, pH, specific conductivity, and temperature were
generally obtained with a water quality probe at the time of sample collection. Field parameter
data for the Bull Hill monitoring wells is provided in Table 9 in Appendix H.
Laboratory results were compared to EPA primary and secondary drinking water maximum
contaminant levels (MCLs) and to the WDEQ drinking water Class I standards. Table 10 in
Appendix H presents the comparison. Of the 108 samples, 84 indicated that one or more of the
MCLs exceeded water quality standards. These include: gross alpha, gross beta, radium 226,
radium 228, radon 222, aluminum, iron, manganese, chromium, and arsenic. The exceedances
for arsenic, iron and manganese are consistent with those observed in the SPLP and NAG
short-term leach tests for waste rock material.
Currently, no federal or state standards exist for radon-222 in drinking water. The standard
proposed by EPA for radon 222 is 300 picocurries per liter (pCi/L) for a community water system
and the proposed alternative MCL is 4,000 pCi/L for individual water wells. These standards
were proposed November 2, 1999 and although, not finalized, have been included as a
screening level comparison.
