top of page
OCU-Group-logo_primary-01.jpg

Kintore Substation - HDD Installation

Project Location:

Aberdeenshire, Scotland

Client Name:

Omexom for SSEN

Project Description:

OCU delivered a design-and-build HDD solution at Kintore Substation to install new cable ducts for twin 132kV circuits beneath the B977, replacing existing oil-filled cables.


The works included full HDD design, topographic survey, buried services tracing and site investigation. Following the discovery of shallow granite bedrock, the duct layout was redesigned from a trefoil to a flat formation to meet settlement and clearance constraints.


Eight HDD crossings were successfully completed within a constrained working area, maintaining safety, traffic flow and network integrity throughout.

Key Stats:

  • 8 x HDD crossings installed

  • 6 x 225mm SDR11 power cable ducts

  • 2 twin 125mm SDR11 earth continuity and fibre optic ducts

  • Drilling in glacial till with cobbles and boulders

  • Bores designed to avoid granite bedrock and protect existing services

2 Months

Duration

Challenge

  • Replacing oil-filled 132kV cables beneath a live carriageway without disrupting traffic

  • Shallow granite bedrock associated with the Kemnay Pluton significantly restricted available drilling depth

  • Existing underground 132kV cables and overhead 275kV lines constrained safe working areas and drilling alignments

  • Tight drill separations of just 2 metres required between multiple HDD installations

  • Maintaining programme delivery during winter conditions including snow, frozen ground and sub-zero temperatures

Solution

  • Undertook detailed ground investigations which confirmed granite bedrock at a much shallower depth than initially anticipated

  • Redesigned the HDD layout from a trefoil duct arrangement to a flat formation to reduce settlement risk and improve constructability

  • Developed detailed settlement modelling to protect the carriageway and surrounding services during drilling operations

  • Engineered drill paths with reduced separations of 2 metres while maintaining safe tolerances between crossings

  • Implemented controlled winter working procedures and programme management to maintain safety and productivity throughout the works

Outcome

  • Successfully completed all eight HDD crossings despite challenging ground conditions and restricted drill spacing

  • Installed, roped and proved power, fibre optic and earth continuity ducts ready for cable installation

  • Zero impact to existing utilities or traffic movements along the B977 during construction

  • No safety or environmental incidents recorded across the programme

  • Works delivered safely, on schedule and within budget despite complex geological and operational constraints

bottom of page