2018-11-05_PERMIT FILE - C1981044A (3)

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Williams Fork Strip Pit and/or natural discharges from the alluvium and coal subcrop. Dissolved solids concentrations recorded at the downstream station averaged 352 mg/L with a maximum concentration of 602 mg/L recorded. Dissolved solids concentrations compazed favorably with the concentrations measured at the upstream station indicating only minor, if any, effects from the mine site. The lab pH ranged from 7.1 to 8.69 and averaged 8.13. Total iron concentration was slightly higher at the downstream Williams Fork station. Total iron concentrations ranged from 110 ug/I. to 11,900 ug/L and averaged 2,713 ug/L. Total manganese concentrations were similar to the upstream station (WF-1) with ranges of less than 20 ug/L to 270 ug/L. The average manganese concentrations were less than 117 ug/L. The dissolved solids concentrations tend to decrease with increasing flow rate. Increasing flow rates is usually the result of early spring snowmelt or summer thunderstorms. This causes a seasonal variation in water quality. The late summer, fall, winter, and early spring months have high dissolved solids concentrations while the spring and early summer months have a low dissolved solids concentrations. These seasonal variations are depicted on Figure 34, Williams Fork River, 1984, Flow and Conductivity. Suspended solids tend to follow an opposite pattern. Suspended solids increase with increasing flow as depicted on figure 35, Williams Fork River, 1984, Flow and Suspended Solids. The results of water quality' sampling of the Yampa and Williams Fork Rivers were compared with applicable Colorado Water Quality Standards and EPA primary and secondary drinking water standards. All four (4) sampling sites exceeded Colorado stream standards for concentrations of lead and manganese. Both Yampa River sampling sites (Y-1 and Y-2) and the upstream Williams Fork sampling site (WF-1) exceeded Colorado stream standards for cadmium. Both Williams Fork sampling sites (WF-1) and (WF-2) and the upstream Yampa River sampling site (Y-2). exceeded Colorado stream standards for copper concentrations. All four (4) sampling sites exceeded EPA primary and secondary drinking water standards for pH, iron, and manganese. Both sampling sites on the Williams Fork River exceeded EPA primary and secondary drinking water standards for lead concentrations. Springs -Water Ouali~ Spring Discharges. Water samples have been collected from three (3) discharges in the general mine area. These discharges aze 1) North Spring, 2) Haxton Spring, and 3) No. I Strip Pit Discharge. Samples have been collected periodically from each discharge. Statistical summaries of the water chemistry data for the North Spring, Haxton Spring, and No. 1 Strip Pit Discharge are presented in Table 28, Summary of Water Quality Data -North Spring, Table 29, Summary of Water Quality Data -Haxton Spring, and Table 30. Summary of Water Quality Data - No. 1 Strip Pit. The North and Haxton Springs are natural springs and have similar water quality; they have either magnesium sulfate or calcium-magnesium sulfate water types. Discharge from [he No. 1 Strip Pit is a sodium- bicarbonate water type. Except for the Haxton Spring, the dissolved solids concentrations are approximately 1,200 mg/L. In the one sample taken from the Haxton Spring, the dissolved solids concentrations averaged 3,750 mg/L. EPA Drinking Water Standards from the two (2} natural springs (North and Haxton) are exceeded for average dissolved solids and sulfate concentrations as well as occasional concentrations of barium, iron, lead, manganese, nitrate, and selenium. The No. 1 Strip Pit dischazge did not exceed any of the present NPDES standards during 1985. Alternate Water Suonly Alternate water supplies for existing wells potentially interrupted or contaminated by mining have been identified. Aquifers that may be interrupted by mining include the Trout Creek, Middle, and possibly the Twentymile Sandstones, with interruption caused by dewatering of the units. The dewatering could occur due to leakage of the water into the mine. There are only a few wells completed in the sandstone aquifers. There are no wells completed in the coals in the immediate vicinity of the mine site. It is unlikely that there will be interruption of any ground water supplies by the mining. There are few well owners in the areas, and those that do pump ground water are located a distance from the mine property. Water rights have been shown for the mine vicinity on the Water Rights Map (Map 18). Permit Renewal No. 4 2.04-24 Revised 3/5/03