Spoil Handling

Spoil handling is an important method characteristic in microtunnelling and pipe jacking projects. For small diameter projects, the spoil or muck from the excavation face is removed in a slurry through a pipe to the surface or may simply be removed through a rotating auger back to the starting pit. In larger diameter tunnels, conveyor systems or muck cars on rails may be used. Excavation and muck removal systems may have the capability to deal with boulders up to a certain diameter by crushing such boulders into smaller fragments before they enter the rest of the muck removal system. When boulders exceed approximately one-third of the diameter of the microtunnel, they may not be able to enter either the crushing chamber for a slurry system or be able to pass through the auger in an auger system. 

Slurry systems mix the excavated soil and rock into a mud slurry for pumping to the surface. For such systems, the excavated material must then be separated from the slurry using shakers and hydroclylones before disposal.