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STIPULATION NO. 6 <br />WITHIN SIXTY DAYS OF PERMIT ISSUANCE, THE APPLICANT <br />SHALL SUBMIT A TECHNICAL REVISION TO THE YOAST <br />PERMIT ADDING A SURFACE WATER MONITORING <br />STATION TO GRASSY CREEK DOWNSTREAM FROM THE <br />CONFLUENCE OF GRASSY CREEK AND SCOTCHMANS <br />GULCH. THE REVISION SHALL ALSO ADDRESS <br />MONITORING FREQUENCY AND PARAMETERS TO BE <br />MONITORED. <br />F. Probable Hydrologic Consequences <br />Probable hydrologic consequences of the proposed Yoast mining <br />operations are discussed in Tab 17 of the permit application package. <br />A summary of that discussion is presented here. <br />Groundwater <br />The probable hydrologic consequences to groundwater resulting from <br />coal extraction at the Yoast Mine include drawdowns to aquifers from <br />pit inflows, and subsequent pit dewatering and production well <br />pumping as well as impacts to groundwater quality resulting from flow <br />through mine spoil. Seneca's predictions of the magnitude of these <br />impacts are discussed below. <br />Groundwater Inflows to Pits and Associated Drawdowns <br />The Yoast Mine will intercept the following hydrologic units: the <br />Wadge Overburden, Wadge Coal, Wolf Creek Overburden, and Wolf <br />Creek Coal. Seneca Coal Company used two models to predict pit <br />inflows as a result of mining activities. The models were the <br />McWhorter (1982) method and the Theis equation, both of which are <br />described in detail in Tab 17 of the PAP. The Theis equation, which <br />was also used to predict drawdowns, consistently predicted higher <br />dischazges for each aquifer with the exception of the Wolf Creek Coal <br />than did the McWhorter method. <br />The more conservative estimates of pit inflows from each aquifer in <br />cubic feet per day are 365 for the Wadge Overburden, 160 for the <br />Wadge Coal, 745 for the Wolf Creek Overburden, and 499 for the <br />Wolf Creek Coal. Vaziability n aquifer chazacteristics in the Grassy <br />Creek and Sage Creek drainages cause variation in the predicted <br />drawdowns. The radial distance to a one foot drawdown in the Wadge <br />Overburden was predicted to be 401 feet in the Grassy Creek drainage <br />Yoast Mine 255 ~ July 4 1995 <br />