54 is moving in the direction indicated by the arrow along a predetermined line where a trench is to be dug the digging chain 28 is rotating in the direction indicated by the arrows in fig3 a after completing the first pass as shown in fig3 a the same trencher 54 has the belt 24 raised the boom 16 lowered and is operated in the opposite direction as indicated by the direction of the arrow the digging chain 28 is rotating in the same clockwise manner in fig3 b as in fig3 a the trencher 54 digs a second trench 58 below the first trench 56 which second trench 58 is dug from approximately the water table 12 to the completed depth 38 because the belt 24 is turned off and raised the wet spoil 42 falls back into the combined first trench 56 and second trench 58 due to the combination of the first trench 56 and second trench 58 expansion of the wet spoil 42 is accommodated without spillage outside of the combined trenches one of the problems with the second pass as shown in fig3 b is that the cutting by the cutting teeth 18 on the digging chain 28 is on the far end of the boom 16 this can cause vibrations along.