300mm - 450mm to 20m deep

Suitable for all ground conditions especially where access, headroom and working space is limited. Electric rigs are used to minimise noise and pollution. Temporary casing avoids collapse or flooding and Tremmie techniques may also be used.

Generally used in situations where there is a wet or granular material overlying clay. The temporary casing is installed to prevent collapse and then is withdrawn following the placement of concrete and steel.