EVALUATION OF FLOW LEAKAGE THROUGH ABANDONED WELLS AND BOREHOLES

Flow leakage through abandoned wells and improperly plugged boreholes drilled between hydrogeologically separated water-bearing zones represent potential pathways of contamination. The present study provides an analytical evaluation of the transient flow rate through these artificial conduits and the resulting hydraulic head distributions when (1) artificial gradients are created by an injection well operating in one of the aquifers or (2) natural hydraulic head differences are present between two confined aquifers. The analysis is conducted by solving the groundwater flow equations in the confined aquifers that are coupled by the flow through the well or borehole. A case study was investigated involving contamination leakage through abandoned wells and improperly plugged boreholes caused by the operation of deep waste injection wells.