Seawater catchments

Service Specifications at Intersections of Marine Protected Areas

Crossings of Marine Protected Areas (MPAs) require trenchless technologies that ensure minimal environmental impact, precise route alignment, and rigorous control of the excavation. The methods used—microtunneling, pipe jacking, and Direct Pipe®—allow pipelines to be installed from land without physically disturbing the seabed within the protected area. This service is defined by the following technical parameters:

• Main applications: Underground crossings beneath AMPs, marine LICs, ZEPIMs, coastal reserves, and areas of special ecological sensitivity to install intake pipelines, outfalls, return lines, process lines, or industrial utilities without directly affecting the marine ecosystem.

• Appropriate construction methods:
– Remote-controlled microtunnel: Ideal for reaching the target area without digging a trench on the seafloor.
– Pipe jacking: For large-diameter structures and deep trenches in saturated soil.
– Direct Pipe: To install permanent steel pipe in a single push with high face stability.
The choice depends on the diameter, range, depth, and environmental conditions.

• Environmental reason for using trenchless methods: The tunnel or microtunnel is constructed from the surface, without disturbing the water column, thereby preventing habitat disruption, sediment removal, turbidity, or harm to protected flora and fauna.

• Terrain conditions and coastal environment: Alluvial soils, saturated sands, silts, and coastal deposits. Key factors include permeability, front stability, water pressure, coastal dynamics, and compatibility with ecosystem preservation.

• Geometry, dimensions, and layout: The pipeline is designed to be laid at sufficient depths to ensure effective separation from the marine ecosystem, thereby preventing damage to seagrass beds Posidonia, breeding grounds, reefs, or sensitive seabeds.

• Diameters and materials: Steel, HDPE, or concrete pipes for non-accessible pipelines. For large diameters, accessible tunnels lined with segments may be used.

• Typical lengths: From tens to several hundred meters, depending on the distance needed to cross the protected area without disturbing its surface.

• Civil engineering requirements on land: Pitheads or launch platforms located outside the protected boundaries, slurry plant, pumping equipment, access points for machinery, and pipe storage and welding areas.

• Integration with marine construction outside the protected area: The connection point between the microtunnel and the subsea pipeline is located outside of the protected area's boundaries, verified by ROV or professional divers.

• Environmental monitoring and regulations:
– Compliance with specific AMP regulations and prior environmental assessments.
– Environmental monitoring plans during implementation.
– Strategies for reducing emissions, turbidity, and noise pollution.

• Quality control and verification: Monitoring of chamber pressure, thrusts, guidance, excavated volume, and alignment. For marine construction projects, final verification via ROV of the connection point and pipeline stability.