June 2011_ M. DEL BRENNA Property of Prysmian

SUBMARINE CABLE INSTALLATION

Data required for effective design

13° Meeting of Marine Observation and Data Expert Group,Brussels, June 8, 2011

Marcello Del BrennaCEO Prysmian Powerlink SrlChairman of the Board, Friends of the Supergrid

June 2011_ M. DEL BRENNA Property of Prysmian

Submarine Cable Installation is done by laying the cable on the sea bottom by using suitable Ships or Barges, that can accomodate the cable on board.

Submarine Cable Protection against potential aggressors like fishing gear and anchors is often required. This is mainly achieved by buring the cable or by other protection method.

The selection of the best installation and protection method requires reliable information and data. Among those:

• Cable route at shore ends and at sea,• Bathymetry, morphology and nature of the seabed• Cable protection requirements,• Expected installation period,• Permitting (planned developments along the route, marine

delimitations, permits and regulations, working windows, flora and fauna protected areas),

• Other utilities along the route,• Offshore and onshore activities and hazards.• Navigation and anchoring areas, fishing activities.

June 2011_ M. DEL BRENNA Property of Prysmian

Desk Top Study & Marine Survey

The Desk Top Study (DTS) and the Marine Survey will provide the majority of the needed information for cable installation and protection.

The DTS will collect all available info relevant to planned developments along the route, permits and regulations, working windows, flora and fauna protected areas, other utilities along the route, offshore and onshore activities and hazards, navigation and anchoring areas, fishing activities.

The output of the DTS is a preliminary cable route that will take into consideration all restrictions above indicated and that will be used as a basis for the marine survey. The Survey will provide information regarding: • Bathymetry, morphology and nature of the seabed• Seabed and sub-bottom soil composition• Location and depth of utilities to be crossed

The output of the Survey is the basis for the final cable route and relevant survey maps for engineering and installation.

June 2011_ M. DEL BRENNA Property of Prysmian

Marine survey – Typical output of marine survey

Survey map

Bathymetry Rendering

June 2011_ M. DEL BRENNA Property of Prysmian

Typical cable protection requirements from a risk analisys

The minimum cable protection by burial is a function of the type and frequency of the hazards present along the cable route.

June 2011_ M. DEL BRENNA Property of Prysmian

Cable route to avoid anchorage area

Final cable route

June 2011_ M. DEL BRENNA Property of Prysmian

Cable lay in protected sea-grass areas

Cable routing to avoid protected sea-grass area where possible

Cable fixation and no burial to limit disturbance

Cable route