Using Time Series Analysis of Coal Mine Hydrographs to Estimate Mine Storage,Retention Time,and Mine-pool Interconnection

Understanding flow-system dynamics of underground coal mine complexes is essential to designing in-situ remediation. Such complexes can be studied by applying time series analysis to the precipitation series and well and mine discharge hydrographs. The Corning mine complex discharges acid mine drainage into Sunday Creek in Ohio, USA. Analysis of the Corning discharge shows that the aquifer has a short (9 days) response time and has little capacity for long-term storage. A time lag of 3–4 days occurs between precipitation and discharge, which corresponds to pressure pulse propagation displacing stored mine water, rather than actual advective flow of water. A gradual decline in hydraulic head is observed from the unsaturated recharge area to the fully flooded discharge area. All well hydrographs show a similar seasonal trend, with mine water levels peaking in early summer, and reaching their lowest levels in early fall, consistent with seasonal recharge patterns. A relatively isolated and fully saturated portion of the mine is sensitive to diurnal barometric pressure, as is typical of confined aquifers, with well water level declining as pressure increases. Other portions of the mine behave as unconfined aquifers, insensitive to barometric pressures. The results also demonstrate the important spatial heterogeneity of the aquifer and indicate that the mine does not behave as a single pool.