I wanted the galvanized domestic water lines to our house replaced with copper. Our house was the middle house of a series built and everybody else has had their galvanized domestic water line rust out. Our galvanized "irrigation" water line has already rusted out.
So....I hired this guy to replace them. He digs a 3'x3'x3' hole every 30'or so and uses this pneumatic mole to drill a hole and when it comes up at the other end, he puts a rope in the hole at it's nose. He then reverses direction and it backs out with a line attached to pull a steel cable through the hole. To that he attaches the copper line and pulls it through. To reverse direction, he twists the air hose about 4 turns in the other direction and it reverses it's direction.