PROJECT SUMMARY:

Seaworks was tasked by Washington Island Electric Coop with performing marine surveys and inspections for an electrical cable crossing project. Washington Island is located at the northern tip of the Door County peninsula, separating Green Bay from Lake Michigan. The island is separated from the mainland by a treacherous straight known as “Death’s Door” and can only be accessed by ferry. The new electrical cable was installed as a replacement to an aging cable that had failed early in 2018.

Before the crossing was designed and permitted, Seaworks performed a multibeam survey of the crossing area. The purpose of the survey was to map bathymetry as well as locate any hazards to be avoided such as debris, wrecks, and rock outcroppings. The data was also reviewed to confirm that no undiscovered archaeological features were present. Challenges included open-lake conditions and water depths of up to 140’.

Seaworks was then tasked with performing ROV post-inspections of the cable as it was installed. This phase was to be performed in mid-December, with difficult winter conditions that included rough seas and freezing spray. Seaworks first collected high-definition ROV video of the landing sites along shore to confirm that previously-installed conduit was in good condition and ready for cable feed by divers. Seaworks then performed inspections of the cables behind the cable-laying barge as they were installed over the course of two days. Inspections confirmed that the cable was laid properly along its planned route and did not cross over any debris or obstructions that could affect its reliability over the coming years.