KARRATHA DAMPIER 132kV LINE UPGRADE

Horizon Power’s Karratha Terminal (KRT) and Dampier Substation (DMP) is connected via a 19km single 132kV circuit KRT-DMP 81.

PROJECT SCOPE

It was Horizon Power’s intention to replace the majority of the line infrastructure due to the assets reaching its end of useful life. Approximately 5.6km of KRT-DMP 81 was replaced in 2012 as part of the Gap Ridge development and was to remain as is.
Partum was engaged to undertake the design for:

  • 13.4km of 132kV powerline.
  • New overhead fibre (OPGW) for the entire line length.
  • Earthworks design for construction pads along a 3km tidal salt flat section.
  • 650m of underground and two cable termination structures due to vicinity to airport.
  • Landing span and gantry at the existing Dampier substation.

CHALLENGES OVERCOME

  • Design of foundation covering extreme variations in soil conditions along the line route - problematic alluvial sand silt mud tidal salt flats (including acid sulphates) up to fragmented and solid hard rock.
  • Ensuring clearance with the Karratha Airport Civil Aviation Safety Authority (CASA) Zone flight landing and take-off profile.
  • 650m of underground cable design including road crossings.
  • Designing the new gantry within the existing Dampier substation that had space constraints.
  • Numerous underground services and fences along the line route.

SOLUTION

  • Extensive PLS CADD modelling to confirm phase and ground clearances including the new OPGW in the existing section.
  • 3D modelling of the cable termination structures to confirm no infringement on CASA zone.
  • Refining the foundation types and designs against preliminary geotechnical data and on-site ID drilling.
  • Optimisation of the earthworks construction pads in challenging tidal terrain.
  • Detailed insulation coordination assessment for the surge arrestor selection.
  • Assessing the current ratings, costs, and practicalities for several cable installation arrangements.
  • CDEGS modelling for the powerline earthing and lightning and confirm voltages on 3rd party assets.