Estimation of vertical infiltration into deep Pittsburgh coal mines of West Virginia-Pennsylvania: A fluid mass balance approach

A total of 35 underground-coal mines of the Pittsburgh coal of West Virginia and Pennsylvania have been evaluated using a fluid mass balance approach to estimate vertical infiltration for year 2000. Two mines have been identified as ideal locations for modelling of an isotropic Kh using a water budget approach. Kh results ranged from 0.03 m/day to 0.15 m/day with median 0.082 m/day. Specific yield for flooding mines ranged from 0.043 to 0.069 based on an assumed 17 m aquifer thickness. A comparison of AVI to mine depth has shown that "shallow" mines (less than 50% of their area below 150 m depth) exhibit decreasing rates of infiltration with depth. "Deep" mines (greater than 50% of their area below 150 m depth) show no relationship with depth. Four hydrogeologic groupings (barrier gain-dominated, AVI ≈ R, barrier loss-dominated, and seasonally influenced) were designated based on mine hydrogeologic status and AVI values.