A bing is the Scottish term for a colliery waste tip. REC were contacted by a client who, as owners of the Waterside Bing at Kirkintilloch, were interested in sampling throughout the bing to determine the coal content and so the possibilities for the recovery of the coal as an economic activity.
The former Waterside Colliery was noted for the production of high quality anthracite coal and so recovered coal would be of particular value. Consequently accurate and representative sampling would be most important.
Bings are the waste piles containing discards from the working of a coal mine. The greater part of this will be stone brought to the surface as a result of necessary excavation to gain the coal, while there will also be colliery washer discards, and other waste materials from the mine operation. Thus while the majority of the bing may be sand and gravel sized pieces of sandstone and mudstone, there will be boulders present as well as timber, steel girders or rails and other debris possibly including mine tubs and larger equipment.
Cable percussive (Shell and Auger) drilling has been regarded as the only traditional method capable of forming boreholes through the bing, but the method does have its limitations and the materials present are difficult to penetrate. Boulders have to be chiselled, while timber and metal obstructions will stop the borehole, requiring the drilling rig to be moved and the bore re-started from the surface.
REC had been aware that Boart Longyear were about to introduce Sonic Drilling techniques where a continuous soil sample can be obtained using a rotary based technique with the addition of low amplitude vibrations to assist the casing and drill string in penetrating soils. The continuous sample of the material penetrated can be logged, photographed and sampled on site. It is capable of penetrating boulders and it was confirmed that metal and timber could be penetrated. As a new technique the rates of production were uncertain, but were indicated to be very much faster than cable percussive techniques.
REC arranged for the new rig to be trialled on the Waterside Bing and so the very first operational use of the rig was undertaken under the supervision and direction of REC. On the first day, the rig was mobilised, tracked to a position near the summit of the bing and then produced 30m of sample before being removed to a place of safety for the night. The samples included sections of timber and boulders of mudstone and sandstone. REC were able to recover representative samples for laboratory testing from throughout the borehole, while the whole profile of the material was laid out allowing the client to see exactly what was present. It was considered that in similar circumstances a traditional cable percussive rig would have achieved less than 10 metres of progress and would probably have been obstructed by timber at 3.5m requiring a new start at an adjacent location.
REC and the client were so impressed by the performance of the rig that an immediate order to undertake a further two days commercial work was organised.
Through their commitment to using the best and most appropriate methods of working in the geo-environmental field, REC have supervised the first operational and first commercial use of the Boart Longyear Sonic Drilling method in the United Kingdom.