Sea Outfall & Shore Approaches
HDD and MT for offshore wind cable landfalls, sea outfall installations, and coastal crossings.
What It Is
TESPL is a sea outfall contractor in India with shore approach HDD and microtunnelling experience in Taiwan and Saudi Arabia. Our coastal works include offshore wind cable landfalls and MT sea outfall drives with in-house sea recovery. Sea outfall and shore approach installations cover trenchless works at the land-sea interface — where pipelines, cables, or outfall structures must cross the shoreline and extend beneath the seabed. The work combines onshore ground engineering with offshore marine operations, requiring coordination across both simultaneously.
Two methods are used depending on the application. HDD is used for shore approach cable landfalls — a bore is drilled from shore beneath the seabed to an offshore exit point, through which a cable or pipeline is then pulled. Microtunnelling is used for sea outfall structures — a tunnel is driven from shore outward to a subsea discharge point, terminating at an offshore diffuser or outfall head.
How It Works
Survey & Ground Investigation (Common to both HDD and MT)
Bathymetric survey, seabed soil investigation, and tidal analysis are completed for both HDD and MT sea outfall installations. Accurate ground characterisation is critical before any offshore trenchless work is initiated — seabed conditions, soil layering, and water depth directly determine bore profile design, machine selection, and marine asset requirements.
HDD Shore Approach — Steps 2 & 3
HDD from Shore
The drill rig advances a pilot bore from shore beneath the beach and seabed, emerging at the designed offshore exit point. Marine support vessels are positioned at the offshore end throughout.
Pipe or Cable Pullback
The product pipe or cable string is pulled through the completed bore from the offshore end to shore in a single operation.
MT Sea Outfall — Steps 2 & 3
MT Drive from Shore
Following ground investigation, an MTBM is driven from a launch shaft onshore, advancing beneath the seabed toward the offshore discharge point.
Sea Recovery
At the offshore end, the MTBM breaks through the seabed at the designed exit point. Divers and marine assets recover the machine — the most operationally complex stage of a sea outfall installation.
Applications
TESPL in Sea Outfall & Shore Approaches
- TESPL has completed sea outfall and shore approach installations across India, Taiwan, and Saudi Arabia — covering both HDD cable landfalls and MT sea outfall drives.
- In HDD shore approach, TESPL executed four drives for cable landfall installation at the Formosa 2 offshore wind project in Taiwan, as specialist subcontractor to Jan De Nul.
- Offshore HDD works have also been completed in Saudi Arabia at Shusha Island and the NEOM Sindalah development.
- In MT sea outfall, TESPL has completed six 2000mm outfalls along India's coastline.
- Five were executed for Adani — with TESPL managing sea recovery operations on each, including marine vessel coordination, diver operations, and offshore MTBM retrieval.
- The sixth was a curved 2000mm drive for GHCL where the alignment changed direction underground to navigate subsurface constraints — sea recovery for this installation was subcontracted to a specialist marine contractor.
Related project references
Adani Water Sea Outfalls
80m length per 5 crossings, 400m total length / 2000mm internal diameter / Adani Water Limited / Gujarat, India
View project details →Formosa 2 OWF — Taiwan
2,155m (4 drives: 509m · 510m · 524m · 612m) / 500mm OD (~20") HDPE SDR11 / Jan De Nul (JDN) / Taiwan
View project details →