Abstract: Re-rounding generally horizontally installed, covered, below-ground flexible conduits with eccentrically deflected upper walls, correcting over-belling, and obtaining primary compaction of soil in the vicinity of the conduits. A casing assembly has a central cylindrical tubular gauging portion nearly filling the conduit diameter, a tapered forward nose portion welded thereto and an off-center smaller-diameter cylindrical tubular rear portion welded thereto and providing continuity along the bottom of said casing assembly but recessed at the top and sides. An air-jet-driven ball-type vibrator is rigidly secured to the bottom of the rear portion, and is actuated by air through an inlet tangentially to the vibrator.