Mole Engineering - Directional Drilling

This Directional Drilling system can be surface launched, or pit launched. The surface launch Directional Drilling system can be steered to drill down at an angle into the ground and then horizontal at the required depth over its length. It can then be steered up out of the ground, so that the pipe/cables can be pulled back. Up to 250mm diameter can be installed over 100 metres in length.

The pit launched drill rig is ideal in tight spaces such as pavements etc. This operates on the same principle as the surface rig, but can fit into an excavation less than 1.3 metres in length. The Directional Drilling system can also be used to drill rock in straight sections.

Applications:- Road/Motorway crossings, river/canal crossings

Limit:- 200mm, up to 100 metres (depending on ground conditions)

Ground Suitability: Ideally self supporting soils containing clays, silts and sands. However it is possible to bore in ballast and rock material subject to specific requirements and prevailing factors.

Unsuitable Ground: Mixed composites.

Excavation Sizes: Varying to suit specific projects.

Risk Assessment: This technique is usually operated with higher volumes of directional drilling than guided boring and therefore should not be used where the ground has vertical fissures or at shallow depths, in particular where larger diameter products
are to be installed.

Pipe Ramming is ideal for larger bore pipes or for laying pipes at shallower depths due to the minimum amount of displacement that is required.

Pipe Ramming requires two excavations in which a sacrificial steel tube is placed. The head of the tube is prepared, to be able to cut through the ground at the tail of the tube, a large mole is positioned. Thus using a hammer action, pipe ramming pushes the tube through the ground into the far excavation (more sections of pipe tube can be welded on for longer lengths).

The debris that has gathered is then forced out using swabs and compressed air.

Applications:- Drains under roads/drives, any large bore pipes/ducts.

Limit:- 1 metre diameter, approx 20 metres in length.

Moling involves the need of two excavations (launch & receive), where the torpedo shaped mole is lined up on the target in the first pit, the mole is pneumatically powered & hammers it's way through the ground.

On entering the receive pit the mole is removed from the air line which is then attached to the pipe/cable to be pulled back through the hole that has been bored.

Ability: Pipes and cable ducts up to 180mm diameter for distances up to 20-25 metres. This technique does not require any anchorage or jacking/thrust blocks.

Ground suitability: Clays, silt, peat and generally soft cohesive material.

Unsuitable ground: Ballasts, sands, gravel, sub base formation, rock and the like.

Excavation Sizes: Typically 2 metres long x 1 metre wide x depth required to suite type of ground and product to be installed for both working and reception pits.

Depth Guideline: 10 x the diameter of product to be installed. i.e. 100mm Cable Duct to achieve recommended minimum boring depths, 1000mm.

Risk Assessment: This system is non-steered and non-tracked. However, the power of the equipment is such it is capable of displacing most minor obstructions without deviation.