Windowless 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. Windowless sampling is particularly suited to restricted access sites, contamination investigations, and where disturbance must be kept to a minimum. Depths of up to 10 metres can be achieved in suitable strata. After driving samplers to the required depth, they can be simply extracted using an integral hydraulic ram on the rig. No separate jacking system is required.
Although the rig operates primarily as a soil sampling tool, the Archway Dart is also capable of conducting Standard Penetration Tests (SPT and SPT(C)) and Dynamic Probing (DP), to BS 1377: Part 9: 1990. The drop weight and drop height can be adjusted on the rig to suit either test. Undisturbed U38/U100 samples can be taken where practicable. The Darts patented weight system (a hole in the weight that allows the drill rods to pass through) means that it is much faster at reaching depth compared with similar drilling rigs I.E The Competitor, Terra rigs etc.
The rig has the facility to drive casing into the ground, simultaneously with a soil sample tube. Using this system means that any overburden/loose ground can be sampled without hole collapse, ensuring that successive samples are accurate from the depth taken. This system also allows for the easy installation of standpipes, gas monitoring tubes or other instrumentation, within the restrictions of the borehole diameter.
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Window sampling rig using attached concrete coring unit before sampling
Dart Rig using Extended Rod System for Rapid Drilling
Window sampling into canal bed to investigate silt levels