Bortech was called upon by a NY based general contractor that was in the process of installing 130' of 24" steel casing pipe under a Metro-North commuter railroad line. The rock formation changed from a medium strength to a very hard volcanic gneiss Basalt formation.

 

The crossing was attempted using disc cutter technology. The required thrust to penetrate this hard rock was too much for the capacity of the bearings. The contractor spent 6-weeks in the project and could not penetrate the rock.

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Bortech was brought in to employ our DTH Horizontal hammer system on this project.

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With this hard rock formation, the correct hammer size and air pressure were necessary to fracture the rock and advance the casing pipe. Because the previous attempt deviated from the design line and grade, we moved the centerline of our drill over and successfully completed the rock bore in five shifts with a recorded penetration rates of 10'-15' per hour. 

 

Since then, we have performed several projects in formations including mixed-face rock, boulders, and cobbles as well as blasted rock-fill zones under busy highways.