To aid in determining the impact of quarry dewatering on Kelleys Island, Ohio, three steady-state, numerical models were constructed using MODFLOW. Paleozoic aged carbonate rocks under thin glacial till deposits form the bedrock aquifer. A 200-acre quarry in the western part of the island began active dewatering in June 2005.
A Case 1 model was constructed assuming a homogeneous carbonate aquifer and was calibrated against measured water levels and quarry discharge rates. Two additional models were created—one assuming an anisotropic aquifer, the other assuming a layered heterogeneous aquifer. All models were compared to measured hydraulic head values to assess a statistical goodness of fit.
The results of this study are not conclusive because none of the three models had an acceptable goodness of fit. This may be due to overly simplistic assumptions regarding the influence of fractures and bedding planes on the ground-water flow system.