Leask Marine offerings at HDD landfalls, marine support to ensure safe breakout, tool recovery, and environmental compliance.
During the pilot drill, we monitor and confirm drill exit; during reaming, we support tool handling and mud monitoring; for drill head & tunnel boring machine (TBM) recovery, we provide the heavy lift, ROV, diver, and vessel support needed to safely bring tools back to surface.
Preparation of Exit Position
Leask Marine can excavate any HDD exit pits if required on the seabed using either:
- Plough Dredging, Diver Air lift, or Mass Flow Excavator from multicat vessel or barge
- Backhoe dredging from a flat-top or jack up barge mounted with a long reach excavator
- Jack-up barge – Drill string recovery, and tool exchange operations
Marine support during Pilot Drill
Leask Marine can assist these operations at the seabed exit point with a number of marine support roles such as:
- Guard vessel & safety zones: Supply vessels and personnel to ensure marine traffic stays clear of the HDD exit area.
- Diver / ROV survey & tracking: We can confirm drill head breakout location and alignment at seabed exit with dive or ROV surveying
- Support barge or vessel: Providing position reference and communications relay.
- Mud return monitoring: Providing divers or marine crew to check for inadvertent returns (“frac-outs”) at seabed.
Reaming Passes
Leask Marine can assist during the reaming operations at the seabed exit point with a number of marine support roles such as:
- Jack-up barge, Spud-leg barge, or multicats.
- Mooring & anchoring: Support vessels are moored near the HDD exit to handle reaming tools if they emerge.
- Cuttings & mud monitoring: Watching for drilling fluid returns at the seabed to ensure environmental compliance.
- Diver/ROV inspection: Verifies borehole exit remains clear and no collapse or scour occurs around exit pit.
- Tool exchange support: In some cases, drill strings, swivels, or reamers may be disconnected offshore for recovery or replacement.
- Guard vessel & safety zones: Supply vessels and personnel to ensure marine traffic stays clear of the HDD exit area.
Drill Head / Tool Handling
Leask Marine can assist managing the HDD drill head or reamer once it exits the bore with:
Recovery to vessel: Divers, ROVs, or cranes retrieve drill heads or reamers from the seabed.
Buoyancy & handling: Large tools are often attached to vessel cranes, lift bags or buoys for safe recovery.
Tool storage: Retrieved equipment is secured on our multicats or barges until reused.
Emergency contingency: If the drill head is stuck at the exit, marine assets support controlled release operations.
TBM or Large Drill Head Recoveries
For long or large-diameter landfalls, HDD may use micro-tunnelling machines (TBM / MTBM) instead of conventional drill strings. Once they break out at seabed Leask Marine can assist with:
- Pre-laid moorings & lifting frames: Used to position multicats or barges over the exit pit.
- Diver / ROV interface: Secure lifting slings or chains as required.
- Heavy lift operations: Multicat vessel, jack-up or flat top barge, recover the TBM to deck for inspection/transport/disconnection
- Environmental precautions: Sediment curtains or containment may be deployed during recovery.
- Seabed reinstatement: After recovery, divers /airlifting / MFE / Dredging / ROVs may backfill the exit pit to restore seabed conditions.
Leask Marine provide a range of general marine support functions across all stages of the HDD operations including:
- Marine Works Management Plan: Method Statements & Risk Assessments.
- Marine communications to authorities and land-based operations.
- Surveying: Multibeam / ROV to monitor seabed before, during, after drilling.
- Safety & exclusion zones: Marine coordination with local authorities.
- Drilling fluid management: Visual and sensor-based monitoring of returns.
- Contingency support: Stuck drill head / string / duct, tool loss, or environmental incident response.