2009-03-19_PERMIT FILE - C1994082A

• Permit No: C1994082A
• IBM Index Class Name: Permit File
• Doc Date: 3/19/2009
• Section_Exhibit Name: Tab 15 Hydrologic Monitoring Program
• Media Type: D
• Archive: Yes

provided in Report 82-874, plus additional data. In addition, most of the ground water level and quality data
collected by the USGS has been incorporated into PWCC's database and is provided in this PAP in lab 7,
Hydrologic Description. Table 15-2, Summary of Surface Water Monitoring Sites, Yoast Mine, provides a
summary of all surface water and spring monitoring sites at Yoast. Table 15-3, Summary of Greund Water
Monitoring Sites, Yoast Mine, provides a summary of all ground water monitoring sites at Yoast. Locations
for all monitoring sites may be found on Exhibit 7-1, Hydrological Monitoring Sites - Yoast Mine (Tab 15-7,
Hydrologic Description).
The 1980 to 1983 USGS study involved the drilling and monitoring of 13 alluvial wells on Sage Creek (see
Table 15-3, Summary of Ground Water Monitoring Sites, Yoast Mine, USGS numbers Al to A13) and 27
bedrock wells (see Table 15-3, Summary of Ground Water Monitoring Sites, Yoast Mine, USGS numbers 1
to 27). In addition, one stream site (with flume) on Sage Creek, YSSF1 (see Table 15-2, Summary of
Surface Water Monitoring Sites, Yoast Mine) was monitored. Precipitation data was also collected by the
USGS at Yoast from July 1980 to June 1983 (see USGS Open-File Report 90-708, Table 15-9, Surface
Water Monitoring Frequencies, Yoast Mine).
USGS monitoring frequencies and parameter lists are given in USGS Open-File Report 90-708. Table and
figure numbers referenced below (this paragraph only) are for that report. Water level measurements for
bedrock and alluvial wells were normally performed monthly and are presented in Table 2 and Table 3,
respectively. That same data is presented in hydrograph form in Figures 4 and 5. Water quality sampling
from bedrock and alluvial wells were performed two to four times a year and are presented in Tables 6 and
7 ,respectively. Water quality sampling of Sage Creek were normally performed two to four times a
month (during spring snowmelt runoff) and monthly (remainder of year) and are presented in Table 8. A
continuous flow record for Sage Creek (April 1981 to September 1983) is presented in Table 9 and
presented in hydrograph form in Figure 6.
PWCC reinstituted hydrologic monitoring at Yoast in 1990. Since most of the original USGS bedrock wells
were to be eventually mined ou[, PWCC drilled eleven new bedrock wells (see Table 15-3, Wells YOV28 to
YWCU31) that exist in areas downgradient of the proposed mining areas. Additional alluvial wells were
also drilled on Sage Creek (WSAL12, also used for Seneca II-W monitoring), Grassy Creek (YGAL15),
Grassy Creek tributaries (YGAL16-18), and Annand Draw (YAAL14).
PWCC generally monitored ground water levels monthly, except during the winter months (see Appendix 7-
2 for ground water level data). Ground water sampling for all bedrock and some alluvial wells were
performed semiannually in 1991 and 1993, and triannually in 1992. In addition, select alluvial wells were
sampled quarterly in 1992 and 1993. All wells drilled by PWCC (see preceding paragraph) were also
sampled once in 1990 (see Appendix 7-4
3