Abstract: An apparatus and method for manufacturing a drainage line unit. The apparatus includes a mandrel having an inner cavity. Rear, upper and front openings communicate with the mandrel cavity. Preferably, a controller connected to at least one sensor is operably positioned to control the apparatus. A pipe feeder feeds perforated vent pipe through the inner cavity of the mandrel from the rear opening to the front opening and therethrough. The pipe is positioned within the inner tube cavity so as to define a void space between the pipe and the wall of the mandrel. A hopper assembly has an exit port positioned for feeding a plurality of plastic bodies into the cavity. A blower produces a sufficient air flow through the mandrel cavity for moving the plurality of plastic bodies to substantially fill the void space so that the pipe emerges from the front opening of the mandrel surrounded by the plurality of plastic bodies.