Contiguous or Secant Piling ~ this forms a permanent structural
wall of interlocking bored piles. Alternate piles are bored and cast
by traditional methods and before the concrete has fully hardened
the interlocking piles are bored using a toothed flight auger. This
system is suitable for most types of subsoil and has the main
advantages of being economical on small and confined sites;
capable of being formed close to existing foundations and can be
installed with the minimum of vibration and noise. Ensuring a
complete interlock of all piles over the entire length may be
difficult to achieve in practice therefore the exposed face of the
piles is usually covered with a mesh or similar fabric and face with
rendering or sprayed concrete. Alternatively a reinforced concrete
wall could be cast in front of the contiguous piling. This method of
ground water control is suitable for structures such as basements,
road underpasses and underground car parks.Ground Water Control---Permanent Exclusion