The work involved the excavation of a suitable trench (400mm wide and 900mm finished cover depth) and the installation of 150mm, 300mm and 630mm cable laid in a trefoil configuration. Also included in the trench profile was up to 2 fibre optic cables and in some places a subsoil drain was required.
The cables are surrounded in a thermally rated compacted bedding material. Mag slab is then installed followed by two layers of either compacted imported basecourse or compacted excavated material which returns the trench back to finished surface level. All compaction operations are regularly tested to ensure quality.
All surplus material is removed from the area to an approved dump site.
Cable installation is carried out in strings which run from turbine to turbine and back to the substation. The cable laying is strategically placed between the roading earthworks and the tower foundation concrete pours. Speed of installation is usually key on these types of projects.
All cable runs are electrically tested once the trench is backfilled and prior to handover back to the client.
The Te Uku Wind Farm project was a massive success for Blackley Construction and we were pleased to be involved with such a large, innovative project.
Key features of the work and/or statistics:
- The project required the installation of a total of 22,935m of trefoil cable
- We used our “Direct Lay” process which see’s a single efficient production line with various machines following each other to complete the installation process
- Trenching, laying cable in bedding material mag slab, imported or excavated backfill and compaction at all levels are completed as the work progresses
- The site contained areas of volcanic ash with inclusions of very hard volcanic boulders, some as large as a car
- The work included the installation of 230 water stops, 4,000m of 100mm subsoil drain, 28 transformer bases and turbine entries and the completion of 300 density tests
Key equipment used:
- Interdrain 2028 Light rock trencher
- Tesmec TRS1100 – Hard rock trencher
- 3 x Marooka conveyor discharge backfill trucks
- 2 x 12 tonne excavators
- Various trucks and minor compaction plant
- Hick Bros Civil Construction
- Job No:
- July 2017