HDD

Our Horizontal Directional Drilling (HDD) capabilities cater for small tight access bores, mid-sized bores and large diameter rock bores using a range of specialised equipment. 

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We are able to merge HDD techniques with our open cut techniques to allow seamless design and construction of directional bores and the instillation of conduits and/or pits.

 

The following elements are considered when determining the HDD sections for each proposed project:

• Restoration costs (Driveways, footpaths, Road crossings)

• Bore Profile (Straight or curved)

• HDD set up locations and proximity to residential dwellings

• HDD exit points

• Lead in excavations (Trench)

• Position of tie-in locations

• Stringing & welding locations

• Existing underground utilities.

 

Process

The HDD crew will perform entry and exit points, stringing & welding of the HDD Pipe strings ready for pull back, tie-ins of the installed pipe strings and backfilling and restoration works, where relevant.

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Benefits

Using HDD methods allows us to install pipelines with credible accuracy and minimal impact on the environment, pedestrians, commuters and existing services along the pipeline route. This method also minimises restoration costs

HDD is the most feasible method of laying a pipeline when there are:

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• Roads, highways, railways and watercourses that need to remain undisturbed

• Manmade structures under built up residential and commercial areas

• Natural obstacles – soft ground and/or under waterways.

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Equipment

• Our HDD fleet includes Vermeer D80 x 100, 24 x 40, 36 x 50, D100 x 120 and Ditchwitch AT30. All rigs include their own vacuum sucker truck and recycling units as required.

• We have a number of mud mixing and recycling systems including vacuum sucker trucks and a MS4 2500/300 Mud Recycling System.

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Case Boring

• Codmah have the capability to bore steel sleeves in 3m, 6m or 12m lengths ranging from 300mm to 1500mm diameter.

• We have a large range of boring units with a selection of cutting heads capable of boring through soil, rock, and sandy conditions.

• With alignment and grade becoming ever more critical in today's services sector, we have introduced an accurate laser guidance system capable of boring distances up 120m with a tolerance of +/- 6mm.

• Our thrust boring units are designed to hydraulically thrust steel casing pipe into a simultaneously bored hole. The boring rig travels along a set of fixed rails embedded into a concrete slab, absorbing the thrust from the advancing boring unit. We use a variety of cutting heads that are carefully selected to suit the ground conditions. These vary from 'conical tungsten tipped bullets, clay picks to cutting discs' that are assembled in an angular or straight formation.

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Process

• The earth is extracted from the cutting face via a segmental auger system positioned within the steel pipe. The spoil is returned to the launch pit where it will be stored or used elsewhere on site.

• This process is repeated until the cutting head reaches the retrieval pit. The cutting head and auger string are then removed, leaving a fully supported steel casing to provide support for the surrounding material and forming a conduit for the installation of the desired service.

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Benefits

• This environmentally friendly method reduces costs normally associated with open trenching.

• Steel sleeved bores provide good mechanical protection of the service that it houses.

• A low MPa flowable grouting mix can be installed to fill the annulus between the steel sleeve and service forming a truly maintenance free installation.