Taking advantage of aquifer heterogeneity in designing construction dewatering systems with partially penetrating recharge wells

Abstract

During construction dewatering, artificial recharge with wells might be required to discharge the pumped groundwater. On the one hand, artificial recharge wells must be placed as close as possible to the construction site to limit the above-ground space for the dewatering infrastructure and the transport costs, while on the other hand, the distance from the dewatering site must be considerably large to reduce the hydraulic impact and minimize overall pumping costs. Commonly, artificial recharge wells are completed with filter screens that penetrate large portions of the aquifer. The present study investigates the efficiency and potential of artificial recharge with partially penetrating wells (PPWs; filter length of 1 m) in heterogeneous aquifers. This was done by conducting scenario modeling of simple dewatering schemes with one abstraction well and one artificial recharge well, as well as with experimental field tests. In these field tests, artificial recharge on a fully penetrating well (FPW), as well as on a PPW screened at a layer of relatively high permeability (300 m/day), is explored. The present study shows that the use of recharge PPWs screened at depth in high-permeability layers of the aquifer minimize the hydraulic impact at the dewatering site. Scenario modeling shows that recharge PPWs can be installed much closer to the dewatering site than FPWs. Assessment of the optimal screen depth of the PPW, as well as the mutual distance between the wells, requires a proper consideration of the vertical variability in the hydraulic conductivity of the aquifer.