Soil Sampling

Structural Soils working on behalf of Halcrow

By Paul Leonard

Structural Soils at work

By Paul Leonard

Investigating the Infill

David along with Gareth (Not in frame), of Structural Soils, investigate the T&S canal at the eastern side of the Bridge over the canal at Dr Newtons way on behalf of Halcrow Group. 12th August 2010. The machine used is believed to be a tracked Comacchio MC300 in percusive sampling mode.

Percussive Sampling

The machine in the photograph is a percussive sampler. Called because it drops a weight onto a hollow pipe to drive it into the soil. The sample is pushed into the pipe by this action and removed for further investigation. The method is called Window sampling. A Window sample is a sample of less than 50mm in diameter usually in soil that contains an average amount of gravel.

Other widely used methods of soil sampling are Bore holes and Trial Pitting.

Boreholes

Boreholes can be either Rotary or Cable percussive. They are used when there is a lot of Gravel or Bedrock to be sampled. They are usually greater than 50mm but less than 200mm in diameter. The tool is again hollow in the middle and the sample is forced into this hollow tube in a core sample. This can again be removed for further investigation.

Trial Pitting

Trial pitting is generally used for areas that do not require high mechanical strength. They are usually hand dug or machine excavated trenches not greater than 4.5m deep. The samples are removed from the trench and placed into containers for further investigation.