Investigation Techniques

Emerson Moore offer a wide range of techniques ranging from trial pitting to advanced rotary drilling techniques, dependant on the project requirements. In addition to our own equipment we also use specialist sub-contractors to ensure the most applicable techniques are available.

Investigation techniques normally include one or more of the following, dependant on the ground conditions and nature of the project:

Trial Pitting
Window Sampling
Dynamic Probing
Percussive Drilling
Augering
Rotary Drilling
Cone Penetration Testing
Geophysics – surface and / or downhole

Trial Pitting

The excavation of trial pits is normally carried out by a mechanical excavator under the instruction of an engineering geologist who records the ground conditions, observing whether any contamination is present, and assessing the engineering characteristics of the materials encountered. This technique provides an excellent, cost effective method for investigating the upper 4 – 5m of the ground profile and provides samples for environmental and geotechnical testing.

Windowless Sampling and Dynamic Probing

Window sampled boreholes provide continuous samples of the soil profile that are retained in plastic tubes for logging and subsequent testing. Window Sample boreholes are driven through soils by a percussive hammer reacting on a steel windowless sample tube containing a removable plastic liner. They are generally advanced to between 6m to 10m below ground level. Dense or stiff ground and other solid obstructions will restrict the depth to which they can be advanced. This technique is ideal for quick investigations for both geo-environmental and geotechnical purposes. The plant offered by Emerson Moore Geosciences is ideally suited to perform these operations being small, track mounted and capable of operating in low headroom conditions or sites with restricted access. Ground water and/or gas monitoring wells can be installed in these boreholes.

Cable Tool Percussion Drilling

Where deeper drilling is required through superficial deposits (soils) Cable Tool Percussion (shell and auger) drilling is often used as a ‘cheap and cheerful’ technique. This method allows a borehole to be drilled to depths of upto around 15m-30m depending on ground conditions. In clay soils a weighted steel tube (known as a ‘clay cutter’) is dropped down the borehole and the soil removed at the surface from the ‘clay cutter’ by hand. In granular materials a shell is used, however water must be added to the borehole above the groundwater table. By repeatedly surging the shell up and down at the base of the hole soil is collected and removed. Various in-situ tests can be carried out to estimate soil strength and density with an option to install groundwater and gas monitoring equipment in the boreholes. However without professional supervision this technique carries very high risks of both cross contamination of samples on environmental sites and poor in-situ test data results e.g. SPT. Samples can be recovered for both geotechnical and environmental laboratory testing.

Rotary Drilling

Emerson Moore operates the latest in rotary drilling equipment, with highly experienced drillers to obtain the best results from these techniques. Rotary drilling uses a combination of rotary action and downward force and the technique may be applied to soil or rock. There are three main options available using the plant and equipment of Emerson Moore Geosciences;
Open Holing – An ‘openhole’ is produced using where there is no need to retrieve intact samples and is undertaken using a tri-cone roller bit or down-the-hole hammer.
Overburden Drilling system – This system is essentially the same as above with the addition of casing. Casing follows directly behind the bit or hammer and allows the hole to be advanced through overburden materials that would otherwise collapse and prevent advancement.
Coring – Coring is a highly skilled and specialised technique. Intact core samples of rock or soil are retrieved by rotating a specially designed barrel into the ground. A flushing medium is required to clear the borehole of cuttings; the choice of flushing medium is not only dependent on the nature of the ground but also the nature of the investigation.

Hollow Stem Continuous Flight Augering

This technique consists of hollow stem augers with an outer spiral forming a continuous flight. Forcing the auger into ground while rotating it advances the hole. As the hole is advanced the soil removed from the base of the hole travels up the flights and emerges at the surface. Samples can be retrieved from the ‘hollow stem’ of the auger and from the arisings at the surface for subsequent environmental and/or geotechnical testing. The presence of a continuous flight from ground level prevents the downward migration of contamination. Hence it is commonly used on sites where either soil or groundwater contamination is suspected.




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Investigation techniques normally include one or more of the following, dependant on the ground conditions and nature of the project: Trial Pitting Window Sampling Dynamic Probing Percussive Drilling Augering Rotary Drilling Cone Penetration Testing Geophysics – surface and / or downhole Trial Pitting The excavation of trial pits is normally carried out by a mechanical excavator under the instruction of an engineering geologist who records the ground conditions, observing whether any contamination is present, and assessing the engineering characteristics of the materials encountered. This technique provides an excellent, cost effective method for investigating the upper 4 – 5m of the ground profile and provides samples for environmental and geotechnical testing. Windowless Sampling and Dynamic Probing Window sampled boreholes provide continuous samples of the soil profile that are retained in plastic tubes for logging and subsequent testing. Window Sample boreholes are driven through soils by a percussive hammer reacting on a steel windowless sample tube containing a removable plastic liner. They are generally advanced to between 6m to 10m below ground level. Dense or stiff ground and other solid obstructions will restrict the depth to which they can be advanced. This technique is ideal for quick investigations for both geo-environmental and geotechnical purposes. The plant offered by Emerson Moore Geosciences is ideally suited to perform these operations being small, track mounted and capable of operating in low headroom conditions or sites with restricted access. Ground water and/or gas monitoring wells can be installed in these boreholes. Cable Tool Percussion Drilling Where deeper drilling is required through superficial deposits (soils) Cable Tool Percussion (shell and auger) drilling is often used as a ‘cheap and cheerful’ technique. This method allows a borehole to be drilled to depths of upto around 15m-30m depending on ground conditions. In clay soils a weighted steel tube (known as a ‘clay cutter’) is dropped down the borehole and the soil removed at the surface from the ‘clay cutter’ by hand. In granular materials a shell is used, however water must be added to the borehole above the groundwater table. By repeatedly surging the shell up and down at the base of the hole soil is collected and removed. Various in-situ tests can be carried out to estimate soil strength and density with an option to install groundwater and gas monitoring equipment in the boreholes. However without professional supervision this technique carries very high risks of both cross contamination of samples on environmental sites and poor in-situ test data results e.g. SPT. Samples can be recovered for both geotechnical and environmental laboratory testing. Rotary Drilling Emerson Moore operates the latest in rotary drilling equipment, with highly experienced drillers to obtain the best results from these techniques. Rotary drilling uses a combination of rotary action and downward force and the technique may be applied to soil or rock. There are three main options available using the plant and equipment of Emerson Moore Geosciences; Open Holing – An ‘openhole’ is produced using where there is no need to retrieve intact samples and is undertaken using a tri-cone roller bit or down-the-hole hammer. Overburden Drilling system – This system is essentially the same as above with the addition of casing. Casing follows directly behind the bit or hammer and allows the hole to be advanced through overburden materials that would otherwise collapse and prevent advancement. Coring – Coring is a highly skilled and specialised technique. Intact core samples of rock or soil are retrieved by rotating a specially designed barrel into the ground. A flushing medium is required to clear the borehole of cuttings; the choice of flushing medium is not only dependent on the nature of the ground but also the nature of the investigation. Hollow Stem Continuous Flight Augering This technique consists of hollow stem augers with an outer spiral forming a continuous flight. Forcing the auger into ground while rotating it advances the hole. As the hole is advanced the soil removed from the base of the hole travels up the flights and emerges at the surface. Samples can be retrieved from the ‘hollow stem’ of the auger and from the arisings at the surface for subsequent environmental and/or geotechnical testing. The presence of a continuous flight from ground level prevents the downward migration of contamination. Hence it is commonly used on sites where either soil or groundwater contamination is suspected.