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Trenchmark Underground Co.Trenchless Contractor
Bundled conduit curving out of red clay at the edge of an open bore pit.

Capabilities › Pilot tube

Pilot Tube Guided Bore

Line-and-grade accuracy for small gravity sewer in tight quarters.

How it works

The short version

A theodolite watches a lighted target in the head while the pilot tube is jacked to the receiving pit, so the alignment is checked continuously instead of hoped for. Where a gravity line has to hit an invert within a fraction of an inch, this is the method that gets it there.

Where it fits

  • Gravity sanitary sewer on a fixed invert
  • Short crossings inside developed street grids
  • Storm drainage under existing pavement
  • Work where a receiving pit is the only open cut

What you get from us

  • Continuous line-and-grade record
  • Shaft design and dewatering plan
  • Video inspection of the finished line
  • Deflection testing to the owner’s specification
Our range for Pilot tube
Product pipe diameter8 – 30 in
Maximum drive length400 ft
Line and grade accuracy±0.5 in over the drive
Pipe materialsVCP, RCP, PVC, steel
Launch shaftFrom 8 ft diameter

On the edge of that range?

Those are the numbers we will put our name to on a bid. If your crossing is longer, deeper or wider than what is listed, say so - sometimes the answer is a different method, and sometimes it is a straight no. Both are more useful than a number we cannot hit.

Ask about your crossing

References

Pilot tube jobs we have finished

Owner, diameter and length - the detail an engineer actually checks.

  • Pilot Tube Guided Bore at Downtown gravity sewer replacement, Georgetown, SC

    Downtown gravity sewer replacement

    Owner
    City public works department
    Location
    Georgetown, SC
    Size
    15 in PVC
    Length
    3 drives, 940 ft total

    Replaced a failing clay line under a historic commercial block from three small pits, holding the invert to a half inch so the businesses above stayed open through the job.

The other three methods

  • Horizontal Directional DrillingHDD

    Steerable bores that go under the obstacle and come back up on the far side.

    • Maximum pipe diameter: 36 in
    • Maximum single shot: 2,200 ft

  • Auger BoringAuger

    Jacked steel casing on grade, the standard for rail and highway crossings.

    • Casing diameter: 12 – 72 in
    • Maximum single drive: 600 ft

  • MicrotunnelingMTBM

    Remote-operated tunnelling for deep, wet and unforgiving ground.

    • Finished diameter: 30 – 96 in
    • Maximum drive length: 1,000 ft between shafts