Is this a joke? I live in the Rocky Mountains and it is very common for gas pipelines to be pulled up the edge of cliffs and left hanging vertical or nearly so. There are limitations to the maximum slope that you can trench, but that is really up to the Engineer and Contractor. I did a 20-inch job once where we welded the pipe on the flat and then walked the drag section off the hill with side booms tied together and anchored by a pair of D-7's with their blades dug into the ground. Not sure what the maximum grade was, but there were foot prints on the dashboard of the hoe that dug the trench (the hoe was tied off before he started down and it was a one way trip since he had no chance of driving back up the hill he dug to the bottom and then drove around to backfill after the pipe was lowered in). That job was closer vertical than horizontal.
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