2015-01-27_PERMIT FILE - C1996083

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Final Technical Report, 2014 Monitoring Well Rehabilitation Program Bowie Mine 18 While the groundwater in all three wells is sodium bicarbonate type, the water quality parameters for each well are variable because they are not from the same hydrostratigraphic unit. Well 2010-1 SS is installed in the sandstone above the upper B -seam, well CWI -DH -60 is installed in the upper B -seam, and well BRL- IP- 14- 67 -D -BLW is installed in the sandstone below the D- seam. 3.2 Well20104SS The goals for a successful rehabilitation of well 2010 -1SS included resolving the issues of high pH values and cleaning off the mud cake buildup on the inside of the casing and screen that prevented the collection of samples for laboratory analysis. A water sample was successfully collected from this well in October 2014, subsequent to the completion of the well rehabilitation program. The static water levels were nearly the same before (1,091.75 ft btoc in October 2013) and after rehabilitation (1,092.4 ft btoc in October 2014). Samples were collected according to EPA protocols and sent to Mountain States Accutest Laboratories ( Accutest Laboratories) in Wheatridge, CO for analysis. The field and laboratory water quality data, as provided by Bowie (2014b), are summarized in Table 2 and copies of the lab results are presented in Appendix B. The baseline pH values ranged from 12.3 to 12.9 s.u. (Bowie, 2014b) and the pH was 11.58 s.u. in the last sample collected at this site (October 2013) prior to rehabilitation. The post - rehabilitation field and laboratory water quality data indicate the high pH issues have been successfully resolved. The field pH was 9.88 s.u. and the lab pH was 9.74 s.u. for the sample collected on October 16, 2014. Though these values are elevated relative to water quality standards (6.5 to 8.5 sm.), they do not exceed the range of values typical to this area. The baseline field specific conductance (conductivity) values ranged from 2,400 to 4,500 µmhos /cm (Bowie, 2014b). The field and lab conductivity values were 2,400 and 2,830 µmhos /cm, respectively, in October 2013 (the last sample collected at this site prior to rehabilitation). The conductivity values were significantly reduced following rehabilitation. The post - rehabilitation were 378 µmhos /cm (field) and 336 µmhos /cm (lab). The water temperature was 20.3 °C on October 16, 2014, slightly cooler than the baseline minimum (Table 3). The well's laboratory water quality results also included the following: hardness total 15.4 mg/L, ammonia (0.50 mg/L), bicarbonate (91.5 mg/L), carbonate (45.4 mg/L), chloride (8.7 mg/L), calcium (6 mg/L), iron dissolved (0.111 mg/L), iron total (4.31 mg/L), manganese total (0.0621 mg/L), phosphorus total (0.071 mg/L), sodium dissolved (73.8 mg/L), sulfate (14.3 mg/L), and total dissolved solids (253 mg/L). Concentrations of arsenic, cadmium, magnesium dissolved, manganese dissolved, mercury dissolved, nitrate, nitrite, selenium dissolved, and zinc dissolved were below lab detection limit (Table 2 and Appendix B) (Bowie, 2014b). The water in this well changed from no dominant type based on the pre - rehabilitation water quality data (October 2013) to sodium bicarbonate type based on the post - rehabilitation water quality data (October 2014) similar to other wells in the area (Figure 2). November 2014 HydroGeo, Inc.