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A Comparative Analysis of Submarine Cable Installation Methods in Northern Puget Sound, Washington
Shaun Austin, Sandy Wyllie-Echeveria, and Martha K. Groom

In this study we analyze environmental impact associated with installation of submarine power cables and telecommunication lines between the islands and mainland of the North Puget Sound region. Using information from permit applications, routing plans, and biological assessments, installation techniques were evaluated for their degree of nearshore habitat disturbance. Nearly 25% of the cable projects approved between 1990 and 2000 had a negative impact to nearshore habitat with over 70% having unknown impacts. The extent of disturbances ranged from geomorphic alterations with complete loss of seagrass (Zostera marina L.) cover to no apparent damage. Large hydraulic trenching devices caused the most severe nearshore damage. Directional drilling and the use of existing conduit produced the least amount of impact while the technique of laying the cable on the sea bottom resulted in unknown environmental impacts. Each installation method described in this study had unique environmental concerns with implications that need further examination.

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