Turbidity Curtain - Davy Crockett Shipwreck
LOCATION: Washougal, WA (Columbia River) TIMEFRAME: April 2011 SCOPE OF WORK: 2400 Linear Feet Type 1 Turbidity Curtain (30-40 ft deep) PROJECT PARTNERS: Owner: US Coast Guard Client: Bergerson Construction Supplier: Layfield
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The Davy Crocket is a 229 feet (70 m) barge that was shipwrecked in 1965, but was exposed three decades later by shifting sands in the Columbia River near Washougal, Washington. When oil was discovered entombed aboard the vessel, the Washington State of Ecology embarked on what became the most expensive maritime cleanup in Washington Sate history.
Unfortunately, the efforts to gain utilization of the local dry docks for deconstruction were unsuccessful due to complex safety, environmental, and liability issues. Instead, contractors decided to encircle the vessel with 850 feet of metal sheet pilings and a turbidity curtain to allow workers to safely dismantle the ship while containing pollution.
One of the main challenges was to contain the oil, chemical, and sediment discharge with a sheet pile cofferdam installed around the vessel during deconstruction and salvage operations. Oil contained within the vessel’s fuel tanks was leaking and the bottom sediment contained high levels PCB’s. The emergency response team required a custom turbidity curtain to be manufactured and shipped within 10 days of order to coincide with sheet pile and salvage operations.
The best solution was the fabrication of a custom turbidity curtain that needed to be economical while durable enough to survive the rigorous environment of a salvage operation. The contractor needed a system that could be installed from the derelict with limited access to heavy equipment and a small deployment area. The decision was made to use a Layfield Type 1.DOT silt curtain to contain the contaminated sediment disturbed by the deconstruction operations since it could be safely deployed from the listing deck of the Davy Crockett.
The salvage and ship breaking operations took approximately 3 months to separate and dewater sections of the vessel for removal by crane to waiting barges. During the deconstruction, the Washington State Department of Ecology and the US Coast Guard monitored water quality levels of the surrounding river and found them to be within required levels.
Following the removal of the vessel the turbidity curtain will continue to protect the river from harmful contamination during the remediation and restoration of the site.