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bedrock TDS concentration is 3201 mg/1 which is well below the livestock standard. Well yields in these bedrock units, the Wadge Coal and Overburden and the Wolf Creek Coal and Overburden, are insufficient for irrigation purposes. The alluvial aquifers that will be affected by the resaturated spoil include the Armand Draw, Upper Grassy Creek, Lower Grassy Creek, and Sage Creek alluvia. Within the Grassy Creek basin, above the confluence with Scotchman's Gulch, the magnitude of the TDS increase will be high immediately below the resaturated spoil, but will be undetectable a short distance beyond within the Upper Grassy Creek Alluvium. This diminution of TDS will result from low hydraulic conductivities in the Grassy Creek Alluvium, additional downgradient chemical changes, and dilution and mixing from shallow bedrock units which discharge to the alluvium. Seneca Coal Company predicts that the maximum TDS increase in the Armand Draw Alluvium will be 58% immediately below the resaturated spoil, attenuating to less than 5% near the confluence of Lower Grassy Creek and Scotchman's Gulch. The predicted TDS increases in the Grassy Creek and Armand Draw Alluvia will not preclude use of the alluvial groundwater for livestock watering, although the low well yields in these areas may already render these aquifers useless for these purposes. In the Sage Creek Alluvium, the predicted TDS increase immediately below.the resaturated spoil is 99%, but attenuates to 0.1%within 1000 feet. The high hydraulic conductivities of greater than 1 ft/day measured in the Sage Creek alluvium, in combination with the large area of alluvial material, provides for a relatively high volume of flux in the Sage Creek Alluvium. Contributions from tributary alluvium and shallow bedrock units~will provide dilution of the spoil discharge as it mixes with much larger volumes of groundwater in the Sage Creek Alluvium. The point at which the TDS increase in the Sage Creek Alluvium is predicted to attenuate to 0.1% is just above a subirrigated field Therefore, the impacts to the field are predicted to be negligible. The minimal increase in downgradient TDS levels will also not affect the suitability of the groundwater for livestock watering uses. Hydrologic monitoring will be implemented by SCC in order to verify the predicted impacts. The proposed hydrologic monitoring program is outlined in Tab 15 of the PAP. Yoast Mine 2] July 6, 1995