Figure 1.
The multi-panel labelled A, B, C depicts three excavation dewatering methods with labelled components. Panel A shows a pit with Settlement tank, Pump, Discharge pipe, Flexible connectors, Header pipe, Wellpoint and riser, and Lowered groundwater level around the excavation. Panel B shows sump pumping with Generator, Power cable, Discharge pipe, Discharge hose, Sump pump, Settlement tank, Groundwater level lowered by sump pumping, Cut-off wall keyed into low-permeability stratum, and Low permeability cut-off wall. Panel C shows a caisson excavation with Jacking arm, Caisson jacks, Caisson is jacked into the ground, Water level in the shaft, Original groundwater level, Telescopic grab mounted on a hydraulic excavator, Proposed shaft depth, Concrete jacking collar, Overcut above Choker ring filled with bentonite slurry, Choker ring, and Steel cutting edge.Different approaches to groundwater control: (a) by pumping, (b) by exclusion, (c) by fluid counter pressures (from Cashman and Preene (2021), with permission)