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The excavation through the collapse employed a technique called fore polling. Long iron rods supported on two steel legs and and a cap are driven into the fall at roof height. The air operated rocker shovel can then remove the spoil for a short distance giving enough room to erect another set of legs. A new set of poles could then be driven over the top into the fall to hold up the roof whilst more spoil is removed. The process is repeated throughout. After many meters of excavation, the face of the fall became to wet to effectively remove and so a series of long steel tubes were driven in to de-water the front end. As the work progressed, the water level was monitored from the other side and over the following weeks new unseen ground was trodden for the first time since mining years. The total distance excavated was approximately forty meters. |