INTRUSIVE GROUND INVESTIGATION
DTS Raeburn have experience in undertaking ground investigations on a wide variety of Greenfield and Brownfield sites.
Services provided include:
The safety of our workforce and members of the public is of paramount importance in all our operations.
Underground Utilities Service Clearance
Where plans showing the locations of underground services are not available, DTS can utilise specialist ground penetrating radar (GPR) and electromagnetic equipment in order to locate all detectable services in the vicinity of the exploratory hole locations.
In areas with a high concentration of buried services, or where services cannot be accurately located, vacuum extraction can be used to safely advance borehole positioned past the depth at which services are likely to be encountered.
Unexploded Ordnance (UXO) Survey
If a desk-based assessment has indicated a potential risk from UXO, site briefings can be given to all personnel and the monitoring of borehole positions can be undertaken using specialist equipment to detect potential UXO.
If required, topographical surveys can also be undertaken to accurately provide the location and elevation of features across a site.
Soil and Rock Sampling
Intrusive geotechnical and environmental investigations can be undertaken utilising numerous methods of sampling depending on the nature of the site, the anticipated ground conditions and the objectives of the investigation.
Cable Percussion Boreholes
Cable percussion boreholes can be used to drill through soils and soft rock to depths of up to 50m and obtain samples for logging and laboratory testing.
Rotary boreholes are suitable for drilling through rock to depths in excess of 100m if required. Core samples can be recovered for logging and laboratory testing.
Window Sampling Boreholes
Window sampling boreholes are typically used to recover shallow soil samples (<5m) for laboratory testing, although sampling to depths of up to 10m can be completed in suitable conditions. These rigs can also operate at locations inaccessible to other equiptment including inside buildings and through narrow passageways/doorways.
Mechanically Excavated Trial Pits
Mechanically excavated trial pits enable a visual inspection of the strata in situ as well as facilitating soil sampling for laboratory analysis.
Hand Excavated Trial Pits
Hand excavated trial pits are commonly used to expose exisiting foundations or buried services, or to recover samples in areas which are otherwise inaccessible. Vacuum extraction can be used for this purpose.
Concrete coring can be used to collect samples for laboratory strength testing.
Restricted Access Borehole Drilling
Restricted access boreholes drilling using modified window sampling, cable percussion and rotary drilling rigs can enable access for boreholes in areas inaccessible to standard equiptment due to low-headroom, limited working area, stairs and/or narrow entrances.
Electrically Powered Drilling Rigs
Electrically powered drilling rigs (both cable percussion and window sampling) can be utilised to eliminate diesel fume emissions when drilling in confined spaces or in areas handling food products.
Where desk-based research has identified a potential risk from historical mining, rotary boreholes can be used to determine the presence or absence of shallow mine workings. Probing or trenching can also be used to determine the location of reported mine shafts. All mining related work in the UK is undertaken under the appropriate permit obtained from the Coal Authority.
Water and Gas Monitoring and Sampling
Groundwater and gas monitoring standpipes can be fitted into all borehole types followed by monitoring of gas emissions and groundwater levels. This monitoring can be undertaken during return visits to site or automatically using continuous monitoring devices.
If required, samples of groundwater can be recovered for laboratory testing using a variety of techniques to suit the objective including disposable bailers, peristaltic pumps and low-flow sampling. Gas samples can also be recovered.
In Situ Testing
Standard Penetration Tests (SPTs) and Cone Penetration Tests (CPTs) can be undertaken within cable percussion, rotary and window sampling boreholes to provide a measure of the strength/density of the stratum.
Dynamic probing enables a rapid assessment of the in situ strength/density of the strata and can also be used to determine the lateral extent of underground obstructions.
Soakaway and Falling Head Permeability Tests
Soakaway and falling head permeability testing can be undertaken in trial pits and boreholes repsectively to determine the infiltration rate of the tested strata and provide data for soakaway design.
California Bearing Ratio (CBR)/Dynamic Cone Penetrometer (DCP)/Mexicone testing can be used to provide data to enable pavement design.
Gas and Groundwater Monitoring
Gas and groundwater monitoring and sampling can be undertaken following completion of drilling if required.
Our laboratory testing services are provided by our group sister company, Terra Tek Limited. A UKAS registered laboratory with capability for a wide range of geotechnical and chemical contamination testing services.
Geotechnical and Environmental Reporting
DTS produce comprehensive factual and/or interpretative reports (including Ground Investigation Reports in accordance with Eurocodes) with verified exploratory hole records and AGS data. Where applicable, design parameters/recommendations relating to the following are also included:
Generic and Detailed Quantitative Risk Assessments (GQRA and DQRA) of ground contamination
Assessment of liability under Part IIa of the Environmental Protection Act 1990
Off-site disposal classification of surplus soils (WAC)
Foundation and pavement design
SLope stability analysis
Retaining wall design
Ground gas risk assessment
Sulphate attack on buried concrete