Rotary Drilled Boreholes

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Central Alliance rotary ground investigation at Parsons Tunnel in Teignmouth, Devon.


Boreholes formed by rotary drilling equipment are normally used when rock or hard or ground is anticipated. Rotary techniques are used to drill through rock or solid geology.  There are two types of rotary borehole frequently used on ground investigation projects, rotary open holes and rotary cored holes.  Rotary open holes are drilled when rapid progress is required on projects such as mining investigations when the structural details of the rock are not necessarily important as we are more interested in the presence of voids that could indicate shallow mine workings. Rotary cored holes are drilled when structural details of the underlying rock are required.  These are generally used in applications such as when a proposed development has heavy loadings or requires deep foundations or when the site is underlain by shallow bedrock.


We own and operate an extensive fleet of rotary rigs including three Fraste PLGs, a Fraste ML, Massenza Mi5, two Massenza MiP3s, a Comacchio 205, a Comacchio 300, a Dando Terrier and a Fraste SLG. Techniques used include conventional coring, Geobore-S wireline, open holing, down-the-hole hammer and hollow stem auger with wireline sampling. Most rigs are multi purpose and capable of dynamic sampling through superficial deposits and standard penetration tests (SPT).

Central Alliance rotary ground investigation.


Rotary Boreholes