Rodgers Contracts - Trenchless Installation Techniques

Horizontal Directional Drilling (Guided Boring) is ideal for the underground installation of gas, electric, water, telecommunication or soil remediation lines - without excavation or trenching. Horizontal directional drilling ensures minimal or no environmental disruption and is an excellent choice for installations in diverse rock and soil conditions. Directional underground drilling is a cost effective practical method for utility installations required to cross under roads and rivers.

Recent schemes have included laying ducting across the M1 which would not have been practical with traditional open cut.

Horizontal directional drilling units install utilities by pilot boring underground. The system uses a removable drill head matched to soil conditions by the operator and a series of drill stems to push and rotate the head. Once the pilot bore is completed, a reamer/backreamer is attached to the drill stem string and pulled back, enlarging the bore wall to comfortably accommodate the product conduit or pipe that is subsequently pulled into place.

Typical installation rates of 100m to 200m per day are achievable (depending on pipe diameter and ground conditions)

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As part of a larger sewer rehabilitation framework contract in Eastern Division DRD Water Service issued a contract to replace the sewers and watermain within Malone Avenue, Belfast.

Due to the large number of residential properties DRD Water Service stipulated that the contract was to be carried out by trenchless installation.

The contract was planned to be split in two separate overlapping phases - replacement of 570m of 5" cast iron watermain with 180mm dia PE (supplied by Total Pipeline Specialists) by pipe bursting with an 85T Scandinavian pipe burster and the relining of 570m of 900mm oval brick sewer by a "Cured In Place Liner" installed by Environmental Techniques.

Once on site it was discovered that the Eircom had laid a 4 way fibre optic duct arrangement immediately above the existing watermain and so the construction method was changed to Horizontal Directional Drilling to enable the contract to be carried out without major excavations.

The contract was carried out over a 12 week period from January 2005 to May 2005 without any major traffic implications.

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As part of a larger sewer rehabilitation framework contract in Eastern Division DRD Water Service issued a contract to replace the sewers and watermain within Elmwood Avenue, Belfast.

Due to the location being adjacent to Queens University and a large number of businesses DRD Roads Service would not grant a road closure other than partial closures at weekends. It was due to this restriction that DRD Water Service stipulated that the contract should be carried out by trenchless construction.

The contract was split in two separate overlapping phases - replacement of 320m of 5" cast iron watermain with 180mm dia PE by pipe bursting with an 85T Scandinavian pipe burster and the relining of 320m of 600mm oval brick sewer by a "Cured In Place Liner" installed by Environmental Techniques.

An additional 200m of 200mm uPVC was laid by traditional open cut construction in Elmwood Mews following a survey of the existing clay sewer.

The contract was carried out over an 8 week period from November 2004 to January 2005 without any major traffic implications.

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Where larger diameter pipes and ducts have to be installed in conditions, which would not allow directional drilling an alternative is the usage of a Guided Auger Bore.

On a recent contract which required a 762mm diameter steel sleeve 55m long to be placed at a depth of 3m across the Westlink in Belfast, to facilitate a configuration of 14nr 100mm diameter sub ducts we utilised a Perforator PBA150 guided auger bore rig for installation of the sleeving.

This rig was set up within a specially constructed thrust pit and the works were carried out within a one week period with no disruption to services or traffic on the Westlink.

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