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Product Report: Ditch Witch's On-Grade System

P RODUCT REPORT by Tom Jackson Laser straight HDD Ditch Witch’s OnGrade system cuts the costs and complexity of gravity ﬂow installations The Ditch Witch OnGrade system comes as a kit and includes the beacon, tracker, calibration ﬁxture, level and a rotating laser. It will also work with most construction grade rotating lasers designed for slope applications. H orizontal directional drilling’s advantages are well known, but the one job that’s proven difﬁcult is gravity ﬂow installations. Utility companies require the slope of these bores to track to within 1 to 2 percent of the design grade so after the pipes are installed water will ﬂow unimpeded downhill. Even the best HDD operators can rarely thread a line that straight. To achieve that level of accuracy in the past, contractors had several non-HDD options. They could open cut a trench from the surface or use a laser guided, pit launched tunnel boring machine. With HDD some contractors had success digging multiple sight holes down to the drill stem for a visual survey and/or physical measurement of the bore path. All of these, however, were more expensive and time consuming than conventional HDD. “There is a tremendous amount of planning that has to be done using sight relief holes,” says Richard Levings,

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