OVERWATER GROUND INVESTIGATIONS

Causeway Geotech have significant experience in both the execution, and indeed scoping, of marine ground investigations. We have strong relationships with key, trusted suppliers which means we have a broad range of specialist marine plant available to us at preferential rates, which allows us to be extremely competitive. Furthermore, this allows us an advantage in programming works, where we can mobilise modern, certified and professionally operated marine plant to sites across Europe at short notice. We believe that the forming and maintenance of strong relationships with key suppliers is key to provision of an efficient, quality service to our client base within budget.

Our experience ranges from sheltered lakes where we have deployed floating pontoons, intertidal marshlands where we have used rigs mounted on unique amphibious barges, through to exposed inshore waters, working in water depths of up to 25m off larger jack-up barges – and everything else in between. This includes working off jack-up barges on sites with large tidal ranges, where the logistical challenges of moving the plant from location-to-location, as well as crew transfer, were overcome through careful planning and resourceful engineering, with floating walkways utilised to great success.

Previous investigations have been carried out for port and harbour developments, bridges, outfall pipelines, marinas, quay wall and large deepwater berth construction offshore wind turbines. In addition to executing overwater ground investigations, we have also carried out works directly relating to marine construction activities (drilling of blast holes for underwater excavations, installation of underwater rock anchors and installation of pressure relief/destressing wells within cofferdams). We also have experience of working on nuclear sector sites to complete ground investigations to inform the design of berthing wharfs.

We have conducted overwater ground investigations using a vast array of floating and static work platforms, including multicat workboats, floating pontoons, spud-leg and jack-up barges. We have experience in working in water of up to 25m depth, at sites including inshore estuaries and near shore wind farm sites. Our services range from seabed sediment sampling by grab sampling techniques – a rudimentary method used to obtain samples often used for contamination testing – right through to the drilling of inclined boreholes off specially configured jack-up platforms. We also offer our own in-house vibracore sampling.

Overwater projects conducted previously by Causeway Geotech have included:

  • Harbour extension projects
  • Bridge projects
    • ground investigation for pier and tower foundation design
    • de-stressing (pressure relief) wells for cofferdams
  • Marine outfall
    • ground investigation
    • drilling of blast holes for construction
  • Energy park developments
  • Offshore wind

We have positive working relationships with a number of key suppliers in the marine market which enables us to provide the full package service to our Clients, which offers budgetary and importantly quality benefits.

Typical methodologies

  • Marine sediment sampling (for disposal at sea criteria analysis)
  • UXO clearance (magnetometer carried out with drilling using stainless steel casing)
  • Cable percussion boring, including specialist soft sediment sampling, in-situ vane tests, coupled with standard sampling and testing
  • Rotary drilling, typically by Geobor S wireline coring techniques
  • Rotary percussive drilling
  • Environmental and geotechnical sampling
  • Packer testing
  • CPTs
  • In-situ pressuremeter testing in both soil and rock
  • Borehole geophysics (downhole logging by televiewer, etc)
  • Chemical testing of samples for assessment of disposal at sea criteria for dredged material.