Ground Investigation

Rotary Drilling

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 operate a broad range of tooling using a varied fleet of rigs and we are confident we can provide the perfect solution for your site.  Our rigs range from the compact multi-purpose tracked Comacchio 205s, through larger track and lorry mounted Comacchio 601/602 and T7 units.

Sonic Drilling

Sonic drilling is an advanced drilling technique which operates on the principle of high frequency vibratory energy generated inside a sonic head to advance a core barrel downwards through a substrate.  Production rates are typically significantly quicker, and sample return and quality often much higher, than other  drilling methods. The system has also been proven to be the optimal method for drilling through challenging ground conditions where old technologies struggle, such as dense granular materials, heavy made ground and landfill material.

All our sonic rigs are dual purpose allowing for sonic methods in the overburden followed by rotary coring follow-on in suitable soils and rock.  This ensures full recovery from ground level to the base of the borehole with a single rig set-up.

Cable Percussion Boring

Cable percussion boring returns information on soils to depth. Complementary in-situ testing techniques include Standard Penetration Testing, Permeability Testing and Borehole Vane Testing.  Disturbed and undisturbed soil samples (including Piston Samples) are retrieved for environmental and geotechnical testing in our laboratories.

Causeway Geotech has several Dando 2000, 2500 and 3000 cable percussion rigs within our fleet.  In addition to this, we have bespoke low ground bearing units comprising specially adapted cable percussion rigs mounted on low ground bearing wide-tracked vehicles to allow access over soft and challenging ground terrain.

Dynamic Sampling

A method of investigation best suited to shallow soils sampling and commonly employed in environmental investigations, dynamic sampling is carried out by either tracked light percussion rigs or hand-held (Carl Hamm) samplers. Samples are retrieved in seamless plastic tubes for logging by a suitably qualified engineer. Window(less) sampling is particularly suited to restricted access sites, contamination investigations, and where disturbance must be kept to a minimum. The track mounted equipment is also capable of carrying out dynamic probe testing. This is a continuous soil test procedure which enables the relative density or strength of the ground to be assessed to depths of 10m or more.

We operate a fleet of Dando Terrier light percussion boring rigs that are easily and efficiently deployed to sites. Coupled with this, for rougher terrain or steep slope access, we have bespoke track dumper-mounted Dando Terrier rigs.  For mid-slope and embankment works, as well as works on railways, we have specially adapted rigs which mount directly to quick hitch fittings of excavators/RRVs.

Trial Pitting & Slit Trenching

Trial pitting is used as a quick and cost-effective method for gleaning a basic understanding of the soil profile across a site, or to supplement information provided by other methods of investigation that are completed concurrently.

Additional testing in trial pits can include infiltration/soakaway testing (in accordance with the guidance as set out in BRE 365), CBR testing and in-situ strength testing.

Cone Penetration Testing

Cone Penetration Tests (CPTs) are carried out using a sonic or rotary rig equipped with Drill’n CPT module, or using traditional standalone CPT rigs.

The advantage of our Drill’n CPT module is that with a single set-up, we can alternate between CPTs and sonic/rotary drilling. We can drill through obstructions, such as cobbles and boulders, a particular problem in ground and glacial soils, before reverting to CPT.  This allows for a high quality, continuous profile of the ground without data gaps.

Ground Water/Ground Gas Monitoring & Sampling

Causeway Geotech installs a variety of groundwater and gas monitoring instruments in a range of sizes.  Groundwater levels are measured using a graduated dipmeter and ground gases monitored using an infra-red analyser.  Multiphase dip meters are employed on sites where there is potential free product within the water column.

We offer the option to undertake low flow groundwater sampling with groundwater chemistry measurement.  This method of sampling provides more representative groundwater samples as it extracts the groundwater at rates comparable to ambient groundwater flow and reduces potential for the mixing of stagnant water with water from the well response zone.  This method also allows measurement of groundwater chemistry (pH, D.O., redox, conductivity, temperature) and turbidity of the purged water before a sample is taken.

Analysis of groundwater samples can be arranged through our laboratory. The results of monitoring and testing often forms a crucial part of Environmental Assessments.

Pre-programmable electronic data-loggers are employed where long term monitoring is required, or where continuous measurements are required for pump tests or tidal cycles.  Vibrating wire piezometers may be installed where monitoring of piezometric levels in low permeability soils are required.

Where long term continuous gas monitoring is called for, wellhead monitoring devices can be installed to record ground gas and flow rate on a continuous basis.  This device can be accessed remotely via an online portal allowing the Client to view the data in real time.

Ground Movement Monitoring

Monitoring of ground movement includes simple techniques such as settlement plates and datum rods.  More sophisticated monitoring of ground movements can involve the use of extensometers, with target magnets placed at multiple levels in boreholes, and borehole inclinometers (used to assess lateral movements), commonly used in slope stability analysis, which are monitored using a biaxial probe.  Our experience includes installation of instruments to depths in excess of 100m to determine settlement of ground associated with disused solution mine workings.

As well as the installation and monitoring of instruments, we can offer interpretation and recommendations through our Geotechnical Design department.