ANALYSIS OF HYDROLOGIC IMPACT OF QUARRYING SYSTEM BY 3-D FINITE-ELEMENT MODEL

The excavation of an extensive quarrying system in alluvial plains to supply building material may induce water table modifications that are not compatible with the natural environment or with the existing activities (e.g., agricultural or recreational) in the area. The hydrologic impact of a set of borrow pits designed to provide the material needed for the construction of an electro-nuclear plant at Trino Vercellese, northwestern Italy, is analyzed by the aid of a 3-D finite element model of subsurface flow. On the basis of some design options, primarily dictated by geographical and economical constraints, the model allows for a realistic prediction of the changes of the free surface profile and for the final selection of the quarry design with the least impact on the environment. The numerical results show that the ground-water regime is not altered either transversely or longitudinally if the excavation volume is fractioned into six distinct cavities and the downstream wall of each cavity is made impermeable through the deposition of a layer of fine sediments or the application of a thin plastic foil. © ASCE. © 1990 ASCE