Two 900m long Horizontal Directionally Drilled bores were to traverse national flood defences, in the form of sand dunes, and a beautiful and popular sand beach at Anderby Creek, Lincolnshire. The bores were to house landfall cables for the Triton Knoll Offshore Windfarm, constructed in contribution to the UK’s drive for sustainability, Net Zero and carbon-neutrality. The HDD methodology was selected for its cost and programme benefits, and its environmental superiority as a trenchless technology method for crossing the beach and dunes.
Although the HDD method offers these advantages, careful control of both design and construction is necessary to manage the ground and environmental risks and to realise all potential benefits. In this project, terms for the cable-laying contract were based on assumed ground conditions at the landfall location, with the actual ground conditions being determined later via detailed ground investigations. To mitigate the risks to the Owner, and to provide specialist expertise to augment the project team, GCG was appointed for a scope covering planning/ approval through to design, construction and close-out of the HDD works.
Our contribution included preparing an environmental risk assessment and supporting the Owner in obtaining Environment Agency approval for the HDD works, supporting the Owner’s project team in specifying and interpreting ground investigations for the landfall cables, reviewing and commenting on the contractor’s HDD design and proposed construction methodology, witnessing the construction works on site, providing advice to the Owner on the contractor’s operations and mud management strategy, reviewing and analysing the performance of the HDD works, producing closeout reports for the Client and identifying lessons learned.
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