Soil Thermal Resistivity (STR)

Soil thermal resistivity testing is required to determine cable design and or trench design prior to cable placement. We test on site along a cable route and in the laboratory on fully dried samples. We can also test ground or soil electrical conductivity for key locations on a cable route.

Soil Environment Services Ltd can test the ground prior to or during any site works, within trenches or in our specialised laboratory. We have been testing soil and backfill to the Energy Networks Association specifications for over 10 years. We test soils, rocks and cable bedding materials such as Cement Bound Sand and in recent years have worked with some of the biggest cable laying companies on the longest cable routes in the UK. Of critical importance is the accuracy of resistivity measurements both on site and in the essential supporting laboratory assessments. Soil Environment Services Ltd is conducting on-going research in this area to understand the soil physics of the environment in order to deliver highly accurate soil resistivity testing measurements.

Field Testing

Our range of equipment is designed to allow full flexibility with in-field soil resistivity testing.

We have experience working in difficult conditions and are able to tailor the equipment to the site.

Thermal probes can be inserted into rock or gravel on site and these very often occur in the same trench.

We will assess the specific needs of the project and the environment within which the cable will be operating to provide specific and accurate measurements.

Soil resistivity testing may be carried out in boreholes, test pits or trenches, or we can take cores out of soil, rocks or roads.

Laboratory Services

Thermal resistivity, thermal conductivity or thermal diffusivity of soil, rock or other material, e.g. Cement Bound Sand (CBS) can be measured in our specialised laboratory and is essential to both support field measurements and assess thermal properties under a range of conditions. We have our own dedicated fully equipped laboratory set up for thermal testing of soils, rocks, trench back-fill, alternative (non-traditional) back-fill and CBS. We are currently progressing through the preparation of systems and procedures for a UKAS accreditation application. However, our laboratory soil resistivity testing is only undertaken by experienced consultants who also have a full theoretical understanding of the processes involved with attention to detail at the research scientist level.

Normally we test to and using the following specifications:

ENA TS 97-1, Version 2 2016

ASTM D5334 – 14

IEEE Std 442 -2017

BS EN ISO 8990: 1996

National Grid TS 3.05.07

BS 1377 – Compaction

All laboratory work is overseen by Dr Robin Davies who has a PhD in soil physics (soil stabilisation) and many decades of high quality research laboratory experience for the former British Coal and central government funding agencies. Several recent years of laboratory work have increasingly been focussed on undertaking thermal testing for aggregate supply and cable installation companies.

All of our laboratory staff have science degrees, have worked on central government funded science projects which included laboratory work and have spent a number of recent years undertaking soil resistivity testing /rock thermal testing.

If you need CBS testing in the laboratory or field, please call us to discuss your exact requirements as sample treatment prior to testing is crucial.

Quality and Standards

Our specialised thermal testing laboratory is UKAS accredited – No. 10768.

Testing is overseen by Dr Robin Davies who has 15 years experience in testing the thermal properties of soils, rocks and aggregates and over 30 years experience in testing the physical and mechanical properties of these materials. All work is therefore based on a full theoretical understanding of the processes involved with attention to detail at the research scientist level. We have pioneered new and novel techniques with statistically valid in-house research to deliver test values of the highest standard to meet the requirements of the following specifications.

ENA TS 97-1, Version 2 2016

ASTM D5334 – 14

IEEE Std 442 -2017

BS EN 8990:1996

National Grid TS 3.05.07

BS 1377

Full project consultancy experience

We tailor testing parameters to your specifications in order for you to design cable trenching and bedding on a project specific basis.

All testing and outputs are conducted to the highest industry standard and in line with current international specifications.

Recent project examples

BAM Nuttall – Rothienorman Subtation https://www.ssen-transmission.co.uk/projects/rothienorman-substation/

OMEXOM Crossaig Substation – Mull of Kintyre