Geotechnical Investigation Over Water

Floating pontoons can be configured around compact drilling rigs, sampling equipment and other specialist ground-investigation plant where the required investigation point is over water.

Rig weight, dimensions, operating loads, crew requirements and tooling are reviewed during planning so the platform can be sized for the intended operation.

The platform can support a range of investigation methods including boreholes, window sampling, dynamic probing, CPT or other specialist testing where appropriate to the rig and project.

The investigation contractor confirms the method, equipment and required working geometry so the pontoon can be configured around the actual test location.

Where the drill string or sampling equipment needs to pass through the platform, the pontoon can be arranged with a suitable central or offset opening.

The size and position of the opening are planned around the rig footprint, drilling point, deck access and stability requirements.

For geotechnical work, it is not enough to consider the static weight of the rig alone. Drilling, probing and extraction can introduce additional reaction forces and concentrated loads.

Where required, steelwork, load-spreading mats or other engineered arrangements can be incorporated to distribute loads across the pontoon and support the temporary works design.

The platform is sized to provide more than just the rig footprint. Space may also be required for operatives, rods, casing, tooling, samples, pumps, generators and other investigation equipment.

Deck layout is planned around safe access, equipment handling and the investigation sequence.

Where several borehole or sampling locations are required, the pontoon can be repositioned between investigation points where site conditions allow.

Movement may be assisted by work boats, suitable propulsion, ropes or other project-specific methods depending on the waterway, platform size and programme.

Accurate drilling and testing depends on the platform remaining appropriately controlled at the investigation point.

Restraint may use ropes, anchors, spud arrangements or other methods selected around water depth, flow, bed conditions, navigation requirements and the forces generated by the investigation equipment.

The modular system can be useful where the investigation location has poor road access or cannot be reached directly by lifting equipment.

Components can be transported to a suitable access point, assembled on the water and moved into position, subject to the site-specific installation plan.

Geotechnical platforms often require a more detailed assessment than a simple access pontoon because of rig loads, drilling forces, openings in the deck and the need to hold position accurately.

More complex arrangements can be supported by temporary works design and stability calculations covering platform size, freeboard, loads, restraint and relevant site conditions.

See our Temporary Works & Stability Calculations page.

Water depth, current, changing levels and the nature of the waterway can all influence the pontoon configuration and restraint method.

These conditions are reviewed alongside the rig and investigation requirements so the platform can be planned for the actual site environment.

The working area can be provided with suitable edge protection, access gates and other controls around the rig and drilling opening.

Depending on the project, FPS can also provide work boats, safety boats and additional water-safety equipment as part of the agreed scope.

Ground investigation over water requires careful control of fuels, oils, drilling fluids, spoil and other materials that could affect the water environment.

Project RAMS and the investigation contractor’s method statement should define the required spill, containment and environmental controls for the works.

Every geotechnical investigation site is different, so the pontoon is planned around the investigation method, rig, working loads, drilling point, water conditions and access constraints.

FPS can deliver the modular system, assemble and position the platform, install the agreed restraint and ancillary equipment, support repositioning where required, and return to dismantle and remove the system at the end of the works.