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RULE 2 - PERMITS <br />groundwater users, and are expected to be localized and temporary in nature. Operational <br />mitigation measures and reclamation of disturbance areas will result in effective restoration of <br />surface and ground water conditions similar to those existing prior to initiation of the PSCM <br />project. <br />The anticipated probable hydrologic consequences of mining coal as proposed in this application <br />are: <br />• Spoil springs near Little Grassy Creek are not expected to be impacted by dewatering of the <br />mine. <br />• Dewatering of the mine workings will be necessary; inflows to the mine during dewatering <br />will be less than 55 gpm. <br />• The potentiometric surface will experience drawdown in the vicinity of the mine workings. <br />Re- filling of the dewatered mine voids and adjacent bedrock and recovery of the <br />potentiometric surface to pre- mining levels is expected to take at least 30 years. <br />• The hydraulic conductivity within the mine workings after mining will be much higher than <br />in the adjacent unmined areas and may affect the groundwater flow pattern and velocity <br />• No significant change to groundwater quality is anticipated. <br />• No effect on beneficial -use wells in the area is expected. <br />• No other significant changes to surface water quantity are anticipated. Limited discharge of <br />mine water may increase flows. <br />• No significant negative changes to surface water quality are anticipated. Limited discharge <br />is of mine water may improve water quality. <br />These consequences are discussed in detail in the following subsections. <br />Potential Impacts to Groundwater and Probable Hydrologic Consequences <br />Groundwater inflow to the mine workings will be from two sources: undisturbed bedrock units to <br />the adjacent to the mine workings, and the spoils aquifer at the reclaimed Seneca II Mine east of the <br />mine workings. Groundwater inflow rates to the PSCM from the adjacent bedrock (overburden and <br />Wadge coal) were estimated using analytical methods based on a line -sink model described by R. <br />W. Stallman (in Ferris et al., 1962). Stallman's equations for the situation in which the head in the <br />aquifer is lowered instantaneously to a given level can be used to simulate both the inflow of <br />groundwater and the resulting drawdown away from the sink. The equation describing inflow is: <br />Qb = 2 ST <br />- t <br />where: Qh = flow rate from both sides of the line sink per unit length of the line sink <br />so = initial constant drawdown <br />t = time since head was lowered <br />S = storage coefficient <br />T = transmissivity <br />• The above equation was used to estimate inflow to mine openings from the onset of mining up to 26 <br />months after mining begins after which time dewatering activities would cease. The model was <br />also used to estimate inflow to the mine opening as they flood after dewatering activities cease. <br />Mine sequencing used for the modeling was based on the sequencing presented on Map 2.05.3 -M2, <br />PSCM Permit App. 2.05 -70 Revision 03/05/10 <br />