Subsea Fiber Optic Cable System Northwest, U.S.A.

The cable has shore landings in Anchorage, Nikiski and Homer, Alaska and Florence, Oregon. TerraSond completed the Desktop Study for the entire route and performed Marine Route Surveys for the Anchorage to Nikiski segment and landing site surveys at Homer, Juneau and Florence.

TerraSond completed a Desktop Study to identify the safest, most technically and commercially viable route for the engineering, construction, installation and maintenance of the fiber optic cable sytem. Goals of the study were to identify potential landing sites, select a viable route for the marine survey and assess any risk along the route. TerraSond met with federal, state and local authorities, fisheries managers, research scientists and hired outside contactors to provide an in-depth study of the route. Elements of the desktop study included:

• Existing seafloor cable systems and pipelines;


• Restricted areas (marine sanctuaries and preservations areas, military areas, shipping routes);


• National and state territorial claims;


• Oceanography and meteorology; and


• Marine geology and physiography;

Our hydrographers conducted marine route surveys to provide a feasible and safe route for the cable system design, deployment, survivability, and subsequent maintenance. These surveys allowed decisions to be made about cable armoring and burial. Over 48 km2 were surveyed in two months. Survey methodologies used during the marine route surveys were:

• 100% multibeam bathymetry using a Reson 8101;


• 200% towed sidescan using an EdgeTech 4200MP;


• Towed magnetometer to detect buried cables and pipelines;


• Seismic sub-bottom profiling;


• Seafloor grab samples; and


• Upland topographic surveys of the landing sites;

From this information, detailed route alignment charts and reports showing all route obstacles and hazards were provided to the client to support the cable route and installation engineering.

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