Southern Ground Testing is a site investigation company specialising in soil sampling and profiling using portable drilling apparatus. Applications for our drilling services include the following:
Environmental sampling such as filling station forecourts to provide samples for chemical analysis. Installations of gas and groundwater monitoring wells. Drilling to prove the competence of the soil p
rofile to aid foundation design of new buildings. Determination of the depth to competent strata where settlement or subsidence has take place prior to foundation underpinning. Slope and embankment stability analysis. Coring of floor slabs to determine the thickness and nature of concrete. We also carry out in situ soil testing such as CBR testing, plate load testing and in situ density determinations. Our drilling operatives have many years experience and our training includes railway safety (PTS), CSCS and St Johns ambulance. Tracked Rig Soil Sampling:
Southern Ground Testing operate several tracked soil sampling and profiling rigs. These units are self propelled rubber tracked percussive rigs. They are transported to and from site on the back of a van. Soil sample tubes are driven into the ground by means of a drop weight which is configured to Standard Pe*******on Test, that is a 63.5 kg weight dropping over 0.75m.Sample tubes are generally 1.0m long and start at 116mm in diameter. The soil is retained within a plastic sleeve which ensures a high quality non cross contaminated sample. Sample tubes are withdrawn from the ground using a hydraulic ram.The optimum depth range for these rigs is 0 to 6m although depths of 10m can be achieved in suitable ground conditions. Standard Pe*******on tests are carried out to provide an indication of relative density of the soil, alternatively hand vane tests can be carried out in the recovered tubes. Where soil profiling only is required the sample tube is replaced by a solid cone. A continuous density profile of the ground is obtained. This dynamic probing is often carried out prior to the installation of piled foundations. These rigs are ideal for the rapid installation of shallow gas and groundwater monitoring wells up to 50mm diameter. Where the borehole is on concrete a coring attachment is fixed to the rig. Coring can take place up to 200mm in diameter and floor slabs up to 1 metre in thickness can be penetrated. Southern Ground Testing run a narrow rig which can access through a standard door width. The rigs require 3 metres of headroom. WHEELED RIG SOIL SAMPLING:
The wheeled sampling and profiling rigs are primarily used for dynamic probing, an application where a continuous density profile of the soil is obtained. However these rigs can also be used for soil sampling where the fixed cone is replaced by sampling tubes. These rigs are very maneuverable and can access almost any location including up and down flights of stairs, through doorways and up and down slopes. The rig is light enough to be carried over obstacles should the need arise. In order to maintain the manoeuvrability of the equipment all of the associated tools such as the jacking system are hand portable. These rigs are most often used in site investigations around domestic dwellings, close to railway lines and in areas of limited headroom(2.40m). Southern Ground Testing operate a wheeled rig configured to Super Heavy Dynamic Probe (Standard Pe*******on Test), which again can access difficult areas such as stairs. The wheeled rigs are normally driven by petrol powered engines. However Southern Ground Testing have a rig which is electric powered. This is rig is used in situations where exhaust fumes are undesirable such as in a basement or in a controlled environment. The wheeled rigs can install gas and groundwater monitoring wells of up to 35mm diameter and have been used to install drive-in piezometers in dense gravels. Hand Held Drilling Equipment:
Hand held window sampling is a technique where soil sample tubes are driven into the ground using the vibrating action of a jackhammer. The sample tubes are withdrawn using hand operated jacks. Southern Ground Testing use an electrically driven jackhammer which can either be powered by mains electricity or by a generator. By running leads drilling can take place up to 100 metres from the power source. The hand held sampling equipment is light and portable and so can be used to access the most difficult of locations, such as steep embankments or wet marshy ground. As there is no drop weight mechanism with this equipment is is not possible to obtain dynamic strength parameters. A visual inspection with perhaps hand vane tesing is possible. This drilling technique is optimum for drilling boreholes of up to 5 metres in depth. Mackintosh prode testing is a light hand held dynamic probe which is used to determine the thickness and density of loose or soft soils. A five kilogramme weight is dropped over 0.50m and the blows required to drive the fixed cone every successive 100mm are recorded. Examples of the use of this equipment may be the investigation of silt lagoons or peat deposits. Gas spiking is simply the driving of a steel point into the ground and the testing the nature of eminated gases by means of a portable gas analyser. An example of this technique might be the pe*******on of a landfill capping layer and the testing of released gases. In Situ Soil Remediation:
With the increased cost of disposing of contaminated soils Southern ground Testing are frequently called on the carry out in situ remdiation of soils. The technique involves the driving of a perforated cone with a hydraulic valve into the ground using pecussive drilling as shown above and below. A mix of the desired agent such as oxygen releasing compound (ORC) or hydrogen releasing compound (HRC) is pumped into the ground using a hydraulic hopper. In the case of ORC, the bacteria naturally occuring in the ground are activated into consuming any hydrocarbon cotamination within the soil. For full analysis of this technique please refer to www.regenesis.com
In Situ Testing:
Southern Ground Testing carry out California Bearing Tests (CBR's), plate loading tests, and in situ density determinations by sand or water replacement methods. CBR testing is carried out to give bearing parameters normally in relation to road construction. Normally the testing is carried out using an excavator as counter weight. Southern Ground Testing have devised a frame where the testing can be carried out using the tracked soil sampling rig as counter weight. This means that CBR testing can be carried out in conjunction with soil sampling if required. Plate load testing is a bearing test where the ground is loaded with circular steel plates via a hydraulic jack and the ground reaction in terms of settlement is monitored using travel gauges fixed to datum bars. Plate load testing may be used to check the compaction of earthworks soils or the suitability of piling mats. A CBR value can also be determined by plate loading where the soil is too coarse for direct CBR testing. Concrete Coring:
The tracked soil sampling rigs (shown above), are fitted with hydraulic coring attachments as standard. This allows for the neat pe*******on of concrete or bitumen hard standing prior to the progression through the underlying soil. Core bits of up to 200mm diameter can be used and concrete of up to 1.50m in thickness can be penetrated. A water flush is used to lubricate to coring and therefore no sparks are created. Southern Ground Testing also operate hand portable electrically powered coring units which can be used to core both vertically and horizontally. Coring of up to 250mm can be carried out with this unit. Once a wall is penetrated it is possible to use the hand held soil sampling equipment to obtain soil samples of the material behind the wall. Engineering Services:
Southern Ground Testing have engineers with over 20 years experience who both supervise and operate all drilling and in situ testing equipment. This is advantageous in that the employer does not have to have a logging engineer present. If required Southern ground Testing can provide typed records of sample holes to with descriptions in accordance BS5930 and Eurocode 7.
