Insitu Testing

A comprehensive array of on site testing to support design of temporary and permanent works.
  • California Bearing Ratio (CBR)
  • Plate Load / Plate Bearing Tests
  • Soil Infiltration / Soakaway Tests
  • Winter Groundwater Monitoring
  • Soil Gas / Landfill Gas Monitoring
California Bearing Ratio (CBR) Testing 
Used in pavement design, the CBR is a standard earthworks test.

The full test is completed using a vehicle mounted test rig, Impact Geotechnical can provide CBR test equipment which is mounted to the tow hitch of a works van, which provides the reaction weight for the test. A piston is then very slowly wound downwards onto the soil at the desired test depth until it has penetrated by 7.5mm with the force applied at the points of 2.5mm and 5.0mm recorded to determine the stiffness and allow the CBR% to be calculated.
Dynamic Cone Penetrometer

Where access is an issue for a works van, or where a large amount of data in a short time is required it might be simpler to consider using the Dynamic Cone Penetrometer (DCP) sometimes called the TRRL probe). 

This is a rapid and reliable test which can be used to determine equivalent CBR in a far shorter space of time, and with the added advantage that it provides a vertical profile of results. 

Carried and operated by hand, the DCP is lightweight and highly manoeuvrable, it is also capable of measuring CBR values in excess of 100% and therefore is suitable for sites where an engineered fill material needs to be tested.

Plate Load Testing
Impact Geotechnical offer a comprehensive service for plate bearing tests, with plate sizes of 150-600mm diameter available. Typically testing is completed using heavy plant such as an excavator as a reaction weight with the required load applied to the plate by means of a calibrated hydraulic jack. 

The settlement of the plate is then measured by our specialist technician by means of a series of dial gauges.
Soakaway / Soil Infiltration testing
Planning Authorities are regulating to ensure that new developments cause less environmental impact; including Sustainable Urban Drainage strategies designed to reduce the volume of water entering the sewerage network and inundating waterways, reduce pollutants from urban run-off and use environmental management techniques such as use of green space in developments to benefit wildlife and end users.
Soakaway testing has seen a significant increase in the past five years and it is increasing likely that this testing will be needed for a project. Each site is different, the access and the geology mean that soakage testing needs to be tailored to suit each individual circumstance.

BRE 365 testing, known as Soil Infiltration testing is conducted in a trial pit. Typically this will be a mechanically excavated trench of approximate 1.5-3.0m depth, which is then rapidly filled with water which is allowed to drain away. These tests should be repeated three times to mimic saturated conditions, the rate of water infiltration over the 75% to 25% filled range is used to calculate the ‘infiltration rate’.
No room for a digger? Hand excavated pits filled with water can be used to provide an infiltration where access for plant is restricted, or where shallow soakaways are proposed.

Soakage testing completed within a borehole known as ‘Variable Head Permeability’ Testing can also be used to derive an infiltration rate. This is sometimes known as a borehole soakaway test and is conducted either during the drilling of a borehole or in an installed well. 
Winter Groundwater Monitoring
Impact Geotechnical can provide specialist services to allow this monitoring to be conducted at an early stage in your project, typically around existing site structures. The process usually involves drilling shallow 100mm diameter boreholes using our tracked mini-rig to allow groundwater monitoring standpipes to be constructed. 

The water level in these wells can then be monitored at whatever frequency is required. Impact Geotechnical can provide a specialist technician to complete this, or this can be done with a tape measure. Where high frequency readings benefit your project, Impact Geotechnical can also provide automatic water level loggers to regularly record level data, for instance where tidal influences may be important.
Soil Gas / Landfill Gas Monitoring
Analysis of the gas being generated by the soil below a site, or a nearby landfill can form part of a detailed Geo-environmental Assessment. Boreholes installed to target potential sources of ground gas are monitored using specialist insitu testing equipment by one of Impact Geotechnical’s specialist technicians to determine the gas composition and flow rates.

This information can then be used as part of an Environmental Risk Assessment. For more information click here to read about Impact Geotechnical’s contaminated land services.