2009-05-22_PERMIT FILE - C1981044A (7)

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may be relatively homogeneous White Sandstone. Ground water samples have been collected from three (3) wells completed in the While Sandstone, These wells are 1) well 81-03A, 2) well 81-04A, and 3) well 81-19. Samples have been collected quarterly since August 1981 for well 81-19 and since June 1982 for wells 81-03A and 81-04A until the site was placed in temporary cessation in 2001. A statistical summary of the groundwater chemistry data for the White Sandstone is presented in Table 17, Summary of Water Quality Data -White Sandstone. Ground water from the White Sandstone is primarily of the sodium- bicarbonate type. One sample taken during the recording period included calcium as the predominant cation. Maximum EPA primary and secondary parameter concentrations are exceeded for barium, chromium, total dissolved solids, fluoride, iron, manganese, pH, and sulfate. In addition, average concentrations for total dissolved solids and lead exceed EPA primary and secondary standards. Dissolved solids concentrations average 858 mg/L with a maximum of 1260 mg/L measured. Mine Discharees Water discharged from the No. 5 mine is of the sodium-bicarbonate type with minor amounts of other cations. The high sodium content is reflected in the small increase in sodium found downstream in the Williams Fork River. Total dissolved solids average 870 mg/L with a maximum of 1178 mg/L reported. The discharge from the No. 5 mine may account in part, for the small increase in total dissolved solids in the Williams Fork River. The increase level of sodium and dissolved solids in the Williams Fork River, downstream from the mine, may be in part due to the natural discharge of water from alluvium and coal subcrop. The lab pH ranges from 7.33 to 8.66 and average 8.23. Total iron concentrations are low compared with the values found in the Yampa and Williams Fork Rivers. Iron concentrations ranged from less than 20 ug/L to 1300 ug/L and averaged less than 307 ug/L. Total manganese concentrations were also low with values ranging from 10 ug/L, to 20 ug/L. A statistical summary of mine discharge water chemistry data is pttisented in Table 18, Summary of Water Quality Data - No. 5 Mine Discharge. Table 18a, 1992 Underground Mine Discharge, depicts water volumes discharged from the No. 5 and No.6 mines during 1992. The water quality of the No. 6 Mine discharge should be very similar to the No. 5 Mine discharge. This is evidenced by the water quality analysis presented on Table 19, Water Quality Comparison: "E" Coal Seam and "F" Coal Seam. Well 86-O1, depicted on the table, was a temporary well completed into the "E" coal seam from [he No. 5 Mine. Alluvium -Water Ouality The water quality of the alluvium in the Williams Fork alluvial valley is generally poor. The water is unsuitable for drinking and is locally unsuitable for agricultural purposes. There is high variability in the water quality between wells in the alluvium. The water quality of [he alluvium may be related to the lithology of the underlying bedrock and/or i[ may be related to the affects of irrigation.. The water quality of the alluvium does not appear to be related to surface water quality. Williams Fork Alluvium. Ground water samples have been collected from three (3) wells completed in the Williams Fork Alluvium. These wells are 1) AVF-3, 2) AVF-5, and 3) AVF-6. Samples have been collected quarterly since June 1981. A statistical summary of the groundwater chemistry data for the Williams Fork Alluvium is presented in Table 20, Summary of Water Quality -Williams Fork Alluvium. Ground water from the Williams Fork Alluvium is primarily of the sodium- bicarbonate type. Sodium constitutes a major cation in solution, although calcium and magnesium also occur in significant proportions in several of the alluvial wells. Total dissolved solids average 1,178 mg/L in well AVVF-3, 1,191 mg/L in well AVF-5, and 1,190 mg/L in well AVF-6, with a maximum recording of 1,890 mg/L in well AVF-5. EPA primary and secondary drinking water standards are often exceeded for barium, cadmium, chloride, chromium, pH, selenium, and sulfate. Dissolved solids, iron, lead, manganese, and sulfate often exceed EPA primary and secondary drinking water standards. Some metals exceed these standards because some of the alluvial wells produce silty samples from which metals are leached by the acid preservative. There is no evidence of changes in water chemistry with time in the Williams Fork Alluvium. Figure 24, William Permit Renewal No. 4 2.04-17 Revised 9/23/03