ABSTRACT
This chapter outlines the philosophy and basic methods for the design of groundwater lowering systems. The observational method allows a rational approach to construction where there is uncertainty over ground conditions or over the most suitable and economical dewatering or ground treatment options. The essential step in the design process is the development of a conceptual model of the ground and groundwater conditions. The conceptual model is based on the available data on ground and groundwater conditions, the proposed construction project and the environmental sensitivities of the surrounding area. Geological layering and structure may have a controlling effect on the geometry of groundwater lowering systems, in particular the well depth and the level of well screens. The potential for groundwater inflows exists whenever tunnels are driven below groundwater level through permeable soil or rock strata. The tunnel acts as a drain, with water flowing into the tunnel by gravity.
