Trefoil Duct Install for 33kV Cable Installation – New Plymouth
Project Manager: Haden Coulton
Job No.: 5337
Site Supervisor: Murray Blackley
Key features of the work and/or statistics:
- The project required 3 ducts to be laid in trefoil in a trench that provided 900mm of cover over the top duct. The ducts were bedded in a thermally rated material and the balance of the trench was backfilled in two layers using basecourse. The prepared surface was then reinstated with asphalt
- 1600m of trench was excavated and reinstated for the project.
- Extensive traffic control required due to high volumes of traffic on the road.
- Some 80 nuclear density test were carried out along with 155 Clegg tests to verify trench compaction.
Key equipment used:
- Interdrain 2028 HRT trencher with truck conveyor
- Various excavators
- Various sizes of hand compaction equipment
- Marooka Tracked backfilling truck
- 4 tonne Sakai Roller
Brief description of the work:
Due to existing services occupying the road shoulder, most of the trenching was carried out in the road which because of the high traffic volumes meant that significant traffic control was required for the duration of the project.
Both the traffic control work and the asphalt reinstatement work were sub-contracted out to local suppliers.
The chain trencher was fitted with an elevating conveyor so excavated material from the road sections of the trench could be direct loaded onto trucks.
All of the duct was laid by hand.