Groundwater rebound in the South Yorkshire coalfield: a first approximation using the GRAM model

The closures of three deep coal mines in the Rotherham area (South Yorkshire, UK), acid the cessation of associated dewatering, have given rise to concerns over possible future pollution of ground- and/or surface-water resources once groundwater rebound is complete. An assessment of the legitimacy of these concerns has been made by applying the recently developed, semi-distributed computer model GRAM (Groundwater Rebound in Abandoned Mineworkings). The extent of workings and subsurface inter-connections relating to the three principal collieries in the Rotherham area have been identified from mine plans, augmented by testimonies of former underground workers, and assessed in terms of their hydrogeological importance. GRAM was used:to predict the rate of groundwater recovery in the workings, and the timing and flow-rates of future surface discharges. The:simulations predict that major surface discharges can be expected no. sooner than the year 2005; and will eventually amount to around 3.9 MI d(-1). It is also predicted that around 0.4, MI d(-1) of. water will flow from the abandoned mine-workings into nearby workings of Maltby Colliery. By analogy with discharges elsewhere associated with seams of similar sulphur content, it is considered that the 'first flush' water will contain around 200 mg/l total iron (maximum estimate 600 mg/l), declining eventually to around 20 mg/l total iron.