Geotechnical Investigation

At TGEN, our geo-environmental site investigations and risk assessments for potential land contamination are regularly undertaken in conjunction with geotechnical investigations in order to provide a cost effective and integrated approach to the investigation of a site. Geotechnical aspects may be required to include:-

Foundation Solutions and Design

Based on site investigation records (logs in accordance with BS5930), data from in-situ testing (e.g. CBR tests, SPTs, Dynamic Probing etc.) and results from laboratory testing (e.g. sulphates, plasticity index (PI), particle size distribution (PSD), triaxal permeability etc.) a range of foundation solutions may be selected (e.g. strip, trench-fill, rafts, piled or vibro-replacement) to suit a wide range of structures from single storey residential dwellings to mutli-storey residential or commercial blocks. Where necessary foundation design may be in accordance with NHBC Standards Chapter 4.2 Building near trees with tree surveys and desiccation assessments included.

Earthworks Design, Specifications and Assessment

Large scale developments may include a significant earthworks component (e.g. cut and fill, reduced level excavation etc.), which may create platforms for piling mats or upon which the base of the construction will be founded. Site works, supervision and in-situ monitoring may be incorporated with our services to include in-situ testing and monitoring (e.g. CBR tests, soil compaction tests, material testing) to allow suitable site won materials to be identified for re-use in the permanent work and/or the suitability of materials imported onto site.

Soakage Tests and Soakaway Design

Soakage tests can be undertaken to determine the soil infiltration rate and therefore the drainage capacity of the soil and its inherent suitability (or not) for soakaways as a drainage solution. At TGEN soakage tests are routinely carried out in accordance with:-
The BRE Digest 365 Soakaway Design method undertaken in trial pits excavated at the site of the proposed soakaway that are filled with gravel if the sides are unstable and rapidly filled with water via a bowser or tanker and the soil infiltration rate is then determined by the rate of drainage from the trial pit. This is repeated several times to obtain the soakage rate.
The BS 5930 Code of Practice for Site Investigation method where the permeability or percolation test can be undertaken in boreholes excavated as part of the geo-environmental or geotechnical investigation using either the falling head or constant head test method.

The borehole test is less expensive and less disruptive to the site although not as accurate as the trial pit method.

Slope Stability Assessment

Site investigations can be designed to include an assessment of the stability of existing slopes, including monitoring of movement and/or recommendations for the design and construction of new slopes and embankments.

Ground Source Heat Pumps

Site investigations can be designed to include a study into the viability of a GSHP, which would include an assessment of the geological and hydrogeological conditions at a site, followed by the excavation of exploratory boreholes to confirm the ground conditions at the site. The information obtained from the investigation can then be used to design the ground loops and if necessary progress to installation.

If you would like further information on geotechnical investigations as a stand alone service or in conjunction with any other of our services then please contact us at