Semester

Fall

Date of Graduation

2009

Document Type

Dissertation

Degree Type

PhD

College

Eberly College of Arts and Sciences

Department

Geology and Geography

Committee Chair

Henry Rauch.

Abstract

Long term drainage quality of five closed underground coal mines in West Virginia and Pennsylvania was investigated for mineral reactions, chemical processes, and hydrogeologic controls. Three mines were flooded and had circumneutral water with dissolved iron and sulfate. Two unflooded mines had acidic water with high concentrations of iron, aluminum and sulfate. The monitoring record ranged from 12 to 35 years for the five mine-pools.;The two acidic mine-pools had large long term declines in chemical concentration and flux. Both mine-pools approached equilibrium for hydrous iron sulfate minerals of the jarosite series. One mine-pool also exhibited equilibrium for the hydrous aluminum sulfate mineral jurbanite.;Annual recharge rate for the unflooded mines was 0.28 and 0.36 gallon/A-min. About 75% of the total annual chemical flux is discharged in a six month period.;Flooding profoundly affected drainage quality of closed mines. Three mines had circumneutral pH after inundation and flushing. Extreme chemical stratification can occur in flooded mines. One mine-pool with two pumping rates had greater chemical concentrations at increased pumping rate.;Significant in-situ acid consumption occurred in all five mine-pools. The unflooded mine-pools consumed 50 to 70% of original mine acidity, and neutralization exceeded 100% in the flooded net alkaline mine-pools. Mineral weathering accounts for most in-situ acid consumption.;Chemical concentration time trends fit a first order decay function. Decay constants for total acidity, iron, sulfate, aluminum and total dissolved solids were on the order of 10-4/day in all mine-pools. Decay times of 30 to 70 years were estimated to approach suitable water composition. Decay constants are useful for estimating long term trends.;Flushing model calculations suggest that chemical concentration change in mine-pools is largely a function of transport of reactants and products, not chemical kinetics.

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