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<br />Homestake Mining Company -Bulldog Mine-Lower Tailing Pond <br />' occurring down gradient from the Lower Tailings embankment. In March 1981, a <br />dedicated monitoring well, WP25, was installed to monitor ground water down gradient <br />from the tailing facility. WP25 was located approximately 500 feet down-gradient from <br />' the toe of the Lower Tailings embankment. No explanation was found in the files <br />regarding the fate of WP25, however, based on conversation with Bob Boppe, an ex- <br />Bulldog Mine employee. WP25 collapsed in late 1983 and WP4 was developed as a <br />replacement well. The monitoring period for WP25 started in March, 1981 and ended in <br />September 1983; the monitoring record for WP4 begins in January 1984 and ended in <br />April 1991. The monitoring results for WP2> are provided on Table 4 and Figure 5. The <br />monitoring results for WP4 are provided on Table 2 and Figure 6a-c. <br />' Another monitoring well, WP15 (drilled as P26), was completed in July, 1981. WP15 <br />was located approximately 700 feet down-gradient from WP25 (870 feet down-gradient <br /> from the slurry cut-off wall) and was developed into bedrock at a depth of approximately <br />' 36 feet from the ground surface. The boring log for WP15 is provided as Figure 10. <br />WP15 was part of the water monitoring program until November 1989, the last time it <br /> was noted to contained water. The monitoring results for WP 15 aze provided on Tables <br />' 3a-b and aze plotted on Figures 4a-d <br /> Prior to the development of the slurry cut-off wall in 1982, three additional dedicated <br /> monitoring wells were installed down-gradient from the proposed slurry wall and pump- <br /> back system site near WP25. The monitoring wells, as shown on Figure 2 and Drawing <br /> No. 1. were developed approximately 120 feet down-gradient from the slurry cut-off <br /> wall, neaz well WP25. As the wells were developed they were numbered P 16, 17 & 18, <br /> but later referred to as Sample Points WP29, 30, and 31. The wells were completed in <br /> July 1982 and sealed into bedrock, approximately 40 to 82 feet from the ground surface. <br /> The boring log for WP29 is provided in Figure 11. Piezometer sketches for WP29, 30 and <br /> 31 aze provided as Figures 12-14. Wells WP29, 30, & 31 were included in the ground <br /> water monitoring program from completion until final samples were collected and wells <br /> abandoned and reclaimed in June 1993. The monitoring results from WP29, 30 and 31 <br /> are provided in Tables 5-7 and the results plotted on Figures 7-9. Where available, the <br /> water elevation for each sample episode is also provided as a reference on both the data <br />' plots and tables. <br /> b) Water Quality Monitoring Results <br />' <br /> The water quality monitoring results from the dedicated monitoring wells discovered <br /> during the file search aze presented on Tables 1 through-7 and Figures 3 through 9. Due <br />' to the variability of sampling frequency and parameters, the data has been segregated <br /> into apre-remediation sampling phase and apost-remediation and closure phase. For <br /> example, the sample results from WP 15 during 1981 aze shown on Tables 3A and Figure <br />' 4a. The sample results from 1984-1991 are reflected on Table 3B and Figures 46-d. The <br /> water level elevation in each well at the time of sampling is also provide for the post- <br />' remediation phase samples, but was unavailable for the pre-remediation phase samples. <br /> <br />