



 
Hi Henry. Is the 4 inches the diameter of the tube or the radius? I'll assume it is the diameter. The top soil is well above the tube, so it is just a boxshape. The top soil needs to fill a space that measures 7" x 12" x 167 ft. Using our volume calculator, that is 3.65 cubic yards. Remember that this doesn't account for compacting of the top soil though  that will vary. The gravel is the rest of the trench minus the volume of the tube. The rest of the trench is So the volumes of gravel and topsoil are 10.8 and 3.65 cubic yards respectively, not accounting for compacting or "falling" of some topsoil in between the bits of gravel. You'd have to ask your contractor about that. Stephen La Rocque.>  


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