Hydraulic fill is a means of selectively emplacing soil or other materials using a stream of water.Borrow pits containing suitable material are accessible at an elevation such that the earth can be sluiced to the fill after being washed from the bank by high-pressure nozzles.The water flow must be well controlled at all times, otherwise the central section may be bridged by tongues of coarse material which would facilitate seepage through the dam later.Hydraulic fill dams can be dangerous in areas of seismic activity due to the high susceptibility of the uncompacted, cohesion-less soils in them to liquefaction.Poorly built hydraulic fill dams pose a risk of catastrophic failure.
