Site Investigation / Ground Investigation

With an increasing proportion of developments occurring on brownfield sites and ever more challenging greenfield sites being chosen for development, there has never been a greater need to carry out adequate site investigations. A suitable site investigation can often lead to project cost savings in the long term by enabling contractors to foresee problems and thus make savings.

Structural Soils employs a wide variety of site investigation techniques to suit any size of project. Its team of engineers can advise on suitable methods for individual projects ranging from small-scale domestic investigations, such as house extensions and new builds, to larger ones for major civil engineering works. The investigations usually include both geotechnical and environmental work.

Many investigations begin with a desk-based study of the available information and, when considering the risks posed to a development by current or previous potentially contaminative uses of the site and its surrounds, a preliminary risk assessment (PRA).

These studies are followed by intrusive site investigation techniques employing techniques such as trial pitting, window sampling and dynamic testing, cable percussion and rotary boreholes, window sampling and dynamic probe testing may be carried out alongside other in situ testing such as plate loading tests or nonintrusive geophysical investigations.

Field investigations are normally followed by both geotechnical and chemical testing. Geotechnical testing is undertaken in the company’s UKAS-accredited laboratories in Bristol, Hemel Hempstead and Castleford, whereas chemical testing is undertaken in laboratories operated by Envirolab (an RSK company) in Hyde, Manchester.

Where required owing to site conditions, longer-term in situ gas and/or groundwater monitoring of a site is carried out by our specialist monitoring team.

Presenting results

The results of site investigations can be presented as either factual or interpretative reports; the latter give recommendations relating to geotechnical and environmental considerations. Exploratory hole and other test data are presented in accordance with the latest British Standards and Eurocode 7. High-quality, computer-generated reports are produced in PDF format and hard copies are supplied if required. Site investigation data can also be presented electronically in AGS format.

Quality assured

Structural Soils is an experienced principal contractor and can assume the relevant duties under the Construction, Design and Management (CDM 2015) Regulations. The company has various construction- and other industry-related accreditations and provides services to a wide range of clients, including some major companies with which it has framework agreements.. The company is certified to an integrated management system encapsulating ISO 9001, ISO 14001 and OHSAS 18001.

Trial Pitting

Trial PittingBack to list

Trial pitting can be carried out by a variety of methods from hand dug pits to machine excavated trenches. Trial pitting is generally carried out to a maximum depth of 4.5m with standard excavation plant and, depending on soil conditions, is generally suitable for most low rise developments. All trial pit investigations are supervised by experienced engineers with a thorough understanding of geology and soil mechanics.

Additional testing in trial pits can include soakaway testing, CBR testing and in-situ strength testing.

Window Sampling and Dynamic Probe Testing

Window Sampling and Dynamic Probe TestingBack to list

Window sampling is carried out by either tracked percussive samplers or hand held pneumatic samplers. Samples are retrieved in seamless plastic tubes for logging by a suitably qualified engineer. Window 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.

Cable Percussive Boreholes

Cable Percussive BoreholesBack to list

Suitable for most projects, cable percussive boreholes are a common method of site investigation. Using a Landrover towed rig or a specialist cut down rig suited to restricted access locations most sites can be investigated. In-situ testing techniques including Standard Penetration Testing, Permeability Testing, Borehole Vane Testing and Packer Testing can all be carried out in the boreholes in order to provide information for geotechnical design. Disturbed and undisturbed samples are retrieved from the boreholes for inspection and logging by engineers and subsequent testing in our laboratories.

Rotary Boreholes

Rotary BoreholesBack to list

Rotary drilling techniques are employed where boreholes are required in very dense gravel or bedrock. Samples of bedrock are recovered in seamless plastic tubes for subsequent logging by a suitably qualified engineer and for laboratory testing. Most of our rotary coring work relies on the use of our Comacchio MC300 drilling rigs which can also obtain continuous samples of soils using dynamic sampling equipment. The rigs are suitable for limited access works.

1964 - 2016 © Structural Soils Ltd.
Operational engineering head office - The Old School, Stillhouse Lane, Bedminster, Bristol, BS3 4EB, UK.
Tel: 0117 947 1000. E-mail -

Head Office - Spring Lodge, 172 Chester Road, Helsby, WA6 0AR, UK.
Tel: +44 (0)1928 726006.