By Karl Dale

The offshore and subsea engineering industries are undergoing a pivotal transformation. As global energy systems diversify and critical infrastructure expands beneath the ocean surface, the requirements for seafloor intervention have become increasingly complex. From oil and gas to offshore wind and undersea cable routing, today’s projects demand a new level of precision, environmental sensitivity, and control.

Traditional excavation methods—mechanical digging and heavy dredging—were once the norm. But as operations move into more dynamic and ecologically sensitive zones, these approaches are no longer sufficient. Stronger currents, tighter environmental regulations, and fragile infrastructure require next-generation excavation systems designed for accuracy and minimal disruption.

Modern seafloor engineering has evolved beyond physical excavation alone. The focus now is on smart systems that combine data, adaptive design and automation. Removing sediment effectively is just the beginning—today’s tools must also safeguard assets, reduce environmental impact and deliver consistent results in unpredictable underwater conditions.

Operators increasingly need tools that are rapidly deployable, precisely controllable and capable of operating safely in challenging environments. This has accelerated the shift toward excavation solutions that blend mechanical reliability with real-time monitoring and modular design.

Controlled Mass Flow Excavation Method

Among the most transformative of these advancements is controlled mass flow excavation (CMFE). Unlike traditional dredging, CMFE uses high-volume, low-pressure water flow to suspend and relocate sediment without direct contact with the seabed. This method dramatically reduces the risk of damaging pipelines or cables and eliminates the need for spoil removal, enhancing efficiency and environmental compliance.

CMFE is highly effective across varied seabed types—from soft sand to compact clay and rock dump—and is ideal for tasks such as pipeline and subsea structure de-burial, cable route preparation, seabed leveling, decommissioning offshore structures, and debris clearance. It is especially valuable in shallow, high-risk areas where conventional methods pose safety and environmental challenges.

Today’s CMFE systems incorporate sonar imaging for real-time monitoring, variable power settings, and compact frames for easy deployment from smaller vessels. These features enable precision excavation in complex settings while reducing operational downtime and risks.

 

 

Uni-FlowX

Decommissioning offshore structures often includes the removal of submerged components, such as pipelines, mattresses and jackets. These operations require a precise and minimally invasive approach. Unique Group’s engineering solutions, such as the Uni-FlowX—a non-contact excavation system equipped with a subsea digger—improve seabed access while minimizing ecological disruption. When paired with pipeline and umbilical recovery systems, it simplifies one of the most technically demanding phases of a decommissioning project.

Unique Group, a specialist in offshore and subsea solutions, has extensive engineering capabilities that span the full life cycle of subsea infrastructure—from planning, design, and installation to inspection, maintenance, and decommissioning. With more than 20 operational hubs worldwide, Unique Group also provides trained field service technicians to support offshore projects on site.

Its in-house Engineering and R&D Division is central to its value proposition, driving the development of bespoke technologies tailored for offshore environments. Recent solutions include diver decompression chambers with integrated monitoring, compact launch systems for rough seas, and buoy platforms equipped with environmental sensors.

The Uni-FlowX CMFE system is the result of more than a decade of R&D, field testing and client collaboration. Uni-FlowX delivers a high-performance, contactless excavation method designed for safety, accuracy and environmental stewardship.

Using high-volume, low-pressure water jets, Uni-FlowX fluidizes and displaces sediment without impacting subsea structures. Its contactless operation reduces risk and simplifies logistics, especially for projects involving buried assets in environmentally sensitive areas.

To ensure precision, Uni-FlowX features real-time sonar imaging for visual tracking—even in poor visibility—and modular construction for easy mobilization.

The complete system includes a launch and recovery system, powered by a 37-kW hydraulic unit, main and clump weight winches, and a data umbilical reel. Integrated variable power control enables operators to tailor excavation force to seabed conditions—supporting accurate, efficient sediment removal.

 

 

Excavating Buried PLEM in Bangladesh

Uni-FlowX has been deployed successfully across applications, including pipeline deburial and seabed leveling. One standout case involved a buried pipeline end manifold (PLEM) in the estuarine waters of Bangladesh—a high-risk, low-visibility environment with powerful tidal currents.

The PLEM was buried under dense silt and sand. With limited diver access and short operational windows, traditional excavation posed too many risks. Unique Group mobilized Uni-FlowX alongside a custom-designed launch and recovery system for fast deployment.

The system’s contactless excavation allowed large sediment volumes to be removed without damaging the buried infrastructure. Sonar imaging provided real-time feedback throughout the process, and the compact system ensured efficient mobilization within tight tidal schedules.

This successful operation demonstrated Uni-FlowX’s core strengths: high-precision excavation, reduced environmental impact, and operational flexibility in complex conditions. It also highlighted the value of a responsive, technically capable engineering partner.

Conclusion

As marine infrastructure continues to grow and reach more challenging environments, the demand for safe, intelligent, and low-impact tools will rise. Systems such as Uni-FlowX embody the future of subsea excavation—balancing performance, environmental care and operational control.

Seafloor intervention is now a multidisciplinary challenge, blending environmental science, engineering and logistics. Unique Group’s comprehensive engineering capability, from equipment innovation to full-service project delivery, ensures that even the most complex challenges in offshore energy and infrastructure can be met with confidence. Through ongoing R&D and a practical, field-focused mindset, Unique Group is helping shape a smarter, more sustainable future for the subsea industry.

Learn more here.

 

Karl Dale is vice president of Unique Group’s Load, Lifting + Mooring Solutions Division.