OnGrade Manual - Ditch Witch

Grade Boring Concepts - 38Theory of OperationOnGrade Operator’s ManualTheory of OperationJob PlansFor most jobs, engineers will lay out the line and will establish the manhole locations, the depth the sewerline needs to run, and the recommended grade for the installation. On jobs where a connection is beingmade to an existing service, the position of the existing sewer line will dictate the depth.Engineers commonly base the plans for a sewer line on the invert, or flowline, of the installation. This is theelevation of the lower surface of the internal diameter of the installed pipeline. Drillers depths are from thecenter of the beacon which equates to the center of the installed pipe. If the engineer has specifiedelevations based on the invert, the driller must subtract half of the internal diameter of the pipe to beinstalled from the values given by the engineer to obtain the correct centerline depth for the housing.Laser PlaneThe laser emits a 360° plane. This allows for offsetlocation of the laser plane by the grade pole.The laser plane is also directional meaning that itwill slope up from horizontal in one direction anddown from horizontal in the other direction.e14om017t.epse14om023t.epsCMW