Also referred to as drilled piers, caissons or bored piles, drilled shafts are a type of foundation system used to support structures with large axial and lateral loads by excavating cylindrical shafts deep into the ground and filling them with concrete. This provides the necessary support for large buildings, bridges, and other infrastructure projects.

• Dry/Open Hole: In open hole construction, ground conditions are stable and a standard rotary drill with various drill tools can be employed.

• Wet/Slurry: The wet or  “slurry” method is used when shafts will not stay open due to the presence of caving soils or groundwater.  Water, polymer or mineral slurry is used during drilling or after shaft construction to keep the shaft from caving prior to concrete placement. 

• Cased Shafts: Casing may be required in unstable ground conditions where caving soils, groundwater, or granular soils are present or for installation through water, voids or contaminated soils.  A casing oscillator or rotator can install (and extract) temporary and/or permanent casing while a drilled shaft is excavated with a casing grab or rotary drill.