What it involves

Installation of a new pipe by drilling a ‘mini-tunnel’ and pulling or pushing the pipe into it. A ‘steerable’ trenchless method of installing new underground pipes.

The Service/Product

  • A pilot bore is drilled from a launch pit at one end of a predetermined route, to an exit pit at the other end
  • The drill head contains a transmitter enabling the operator to know the position, depth, pitch and roll of the drill head. This enables continuous adjustments to the line and level to be made throughout the drilling process
  • When the pilot bore is complete, the drill head is replaced with an appropriate hole opening device (reamer), which is rotated back through the bore increasing the diameter
  • When the target diameter is achieved, the reamer is replaced by a swivel and towing head, the pipe is attached and pulled through the bore to complete the installation

Our Process

  • A Survey of the proposed route and examination of all known utilities in the area is critical for success.
  • Launch pits and reception pits should be established at each end of the bore – can be surface launched and received, however typically this requires a connection up and down stream so pits are often sensibly used.
  • The drill head transmitter should be tested for functionality and accuracy before launch
  • Drill the pilot, checking the line and level at all times
  • Check levels in launch and reception pits
  • Enlarge the hole, typically using a reamer, and maintain the hole integrity by injecting drilling mud
  • Check and confirm invert levels in launch and reception pits
  • Install the pipe
  • Make good the launch and reception pits if created.


  • Pipes from 50mm to 1200mm diameter
  • Known ground conditions, including likelihood of rocks or other major obstructions.
  • Locate all buried structures and utilities in the area
  • Identify extent and depth of foundations of all structures in area

When to use Directional Drilling?

  • Some pipes, sewers or drains have problems with their gradient such as dips or bellies. Pipe bursting or lining would only clone these problems in the rehabilitated pipe
  • In this scenario and for other reasons, it can be appropriate and cost-effective to use Directional Drilling to create another pipe beside the existing one, without having to resort to trenching and all the associated disruption. Consideration has to be given to the length of the run in relation to the pipe diameter, pipe type, soil resistance etc. to determine which lengths are possible with available machinery.

Why choose the McAllister Group for Directional Drilling

Experience – Directional Drilling is an activity where experience is key due to the varied nature of the ground and site set-ups. The McAllister Group possesses the necessary experience in house to use this application; the company can also gain from the knowledge of a number of specialist partners who have a broader range of equipment and vast

Approach – We therefore frequently recommend Directional Drilling when lining and other solutions are inappropriate; on occasion and depending on the diameters and site situations we will either install a new run ourselves or oversee one of our partners completing the job