Rotary drilling techniques are employed where penetration is required through very dense or very stiff soils, or into bedrock. Standard methods employed may be subdivided into rotary percussive and rotary coring. We also offer open hole drilling methods without compressed air flush for investigation into voids relating to issues such as karst topography or investigation of old mine workings.
Where coring is undertaken, we have a vast array of systems available, from conventional core barrels of various diameters, through wireline systems such as Geobor S where samples may be recovered in seamless plastic tubes. Most of our rotary drilling work relies on the use of our range of Comacchio and Beretta drilling rigs which can also obtain continuous samples of soils using dynamic sampling equipment. The rigs are suitable for limited access works. Within our fleet, we have a broad range of lorry and track mounted rotary drilling rigs, affording us access to all types of sites, from urban streets to mountainous wind farms where our low ground bearing tracked carriers, including support units, come into their own.
Standard equipment and methods within our capabilities include:
- Track and lorry mounted Comacchio, Beretta and Hanjin D&B drilling rigs
- Rotary percussion systems, including Symmetrix, Robit and Odex cased full-hole drilling
- Open-hole drilling
- Conventional rotary coring, employing metric T2-86, T2-101 core barrels, as well as T6H barrels (commonly used in tandem with high pressure dilatometer testing)
- Wireline coring, including double (PQ) and triple tube type (PQ3 and Geobor S)
- Dual purpose combined dynamic sampling and rotary drilling rigs (Comacchio 205 and 405), with cased dynamic sampling employed through overburden, complimented with undisturbed sampling and SPTs, followed on by rotary drilling methods through very stiff to hard overburden/bedrock.
In tandem with rotary drilled boreholes, specialist in-situ testing is commonly specified, including high pressure dilatometer (HPD) testing, packer testing, borehole geophysics (such as televiewer).
Where required, such as on contaminated sites and restrictive urban settings, drilling flush may be recycled to avoid discharge to ground level, thus ensuring minimal disturbance and reducing the risk of cross-contamination. The effluent flush may then be periodically refreshed, with the waste liquid pumped into sealed IBCs and removed from site for appropriate disposal by a licensed waste carrier.