Flow occurrence between confined aquifers through improperly plugged boreholes

A borehole drilled through the impermeable layer separating two confined aquifers represents a potential conduit for the migration of contaminants between the aquifers if the borehole is improperly plugged. Source characterization studies conducted in contaminated aquifers require flow rate estimates through the leaky borehole in order to gauge the impact of the contaminant loading into the aquifer. Equations of the flow rate through an improperly plugged borehole and the resulting hydraulic head distribution in the aquifers were derived using a series-expansion solution of the governing steady-state groundwater flow equations. The applicability of the derived expressions was reviewed by predicting flow rates through leaky boreholes in hydrogeologic settings documented to be susceptible to cross-contamination via artificial conduits.