Investigation Methods

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Boreholes

We are able to undertake Continuous Flight Auger (C.F.A.) boreholes, Cable Percussive boreholes, Window Sampling boreholes and even Hand Augers to suit the individual site investigation. As part of these investigations we are able to retrieve both disturbed and undisturbed sampling as well as undertake in-situ testing and convert the boreholes to a variety of installations from standpipes to deep datums.

Our rigs allow depths of up to 70m to be achieved, however we commonly drill to depths of between 5m and 30m. The borehole depth, spread, number and type will be dependent on the purpose of the investigation and we are able to offer advice with regards to planning your site investigation.

Chelmer Site Investigations Drilling Team Working On Site

Trial Pits

Trial Pits can be carried out using hand tools, mini or large mechanical excavator depending on access and/or ground conditions. Excavations exceeding 1.5 meters in depth are shored as necessary, in accordance with Health and Safety regulations.

Hand Dug Method

This method is used to expose existing foundations for subsidence or new build investigations on domestic or restricted/internal access sites and can also be used for contamination or CBR sampling.

Machine Dug Method

The machine dug trial pits are suitable for new build design, contamination, soakaway testing, exposure of deeper existing foundations or locating services such as deep drainage or sewers etc.

In-situ Testing and Sampling

SPT/CPT tests are carried out when mechanical drilling is being undertaken, however Shear Vane or Mackintosh Probe tests along with disturbed sampling are normally utilized when carrying out trial pitting.

Dynamic Probes

The Dynamic Probing test is used to determine the resistance of soils in situ to the intermittent penetration of a cone, driven dynamically in a standard manner and in accordance to B.S. 1377: Part 9.

The equipment consists of a 90° cone which may be sacrificial or retained for recovery, a series of extension or driving rods, a torque wrench and a driving device.

There are two type of test: Heavy Dynamic Probing (DPH) and Super Heavy Dynamic Probing (DPSH). The dimensions of the cone and the mass and drop height of the driving weight differ between the two tests.

The extension rods used in the test are either 0.5 metre long (for top of the hole) or 1 metre long, manufactured from 35mm diameter heat-treated alloy steel, with graduations marked every 10cm along their length. The rods are flush-coupled and designed such that rod ends butt-up fully against each other when driving, forming a continuous jointed series with a straight axis. The thread form has been specifically designed for resistance to the driving force. Rods are furnished with spanner flats at both ends to facilitate connecting and disconnecting.

The driving device may be an Automatic Trip Hammer or a purpose-designed Probing Rig with characteristics conforming to BS 1377: Part 9.

Coring

Whether we are using our coring rig as an alternative method to hydraulically breaking out concrete prior to undertaking a borehole or whether we are taking concrete and/or asphalt samples for materials testing, our compact and manoeuvrable diamond tipped coring rig is perfect for both tasks.

Boasting the most powerful electric or generator powered coring rig in its class, together with our highly skilled, trained operatives we can get to practically any location needed.

Other Services

Laboratory

Chelmer established an ‘in-house’ testing Laboratory with the intent to provide a high quality service and turnaround time of test results that is second to none and that compliments the Site Investigation service.

Consultancy

Offering a comprehensive range of interpretative reporting, the Consultancy has Geotechnical Engineers, Geo-Environmental Consultants, Environmental Geoscientists and Geologists.

Drainage

Following numerous requests from our existing client base, the decision was taken to form a Drainage department within Chelmer. This formation proved highly successful and we are now able to provide an extensive array of services.

Contamination and Remediation

Remediation and regeneration of brownfield sites is becoming a key and essential service to enable the redevelopment of sites, especially within the housing sector. Chelmer can provide investigations to assess contaminated sites and can undertake the necessary remediation works to provide an end site suitable for redevelopment.

Surveying

Chelmer can offer a wide range of detailed and efficient surveying services including full site topographical, movement monitoring, wall verticality and utility tracing surveys.