40,000 cubic yards of contaminated sediments to be removed from Blair Waterway.
(Tacoma-September 25, 2015) The Port of Tacoma began dredging contaminated sediments in Blair Waterway on September 15 in preparation to expand Pier 4. The Port detected a marine biocide, called tributyltin, while completing a dredging inspection for the location evaluation to expand Pier four for larger ships. The Port of Tacoma has agreed to complete the cleanup of the sediments, which the E.P.A. will oversee.
The Port of Tacoma will dredge an additional 500,000 cubic yards of clean sediment to make the base of the pier deeper as part of the pier expansion.
"In an effort to contain costs and remain competitive, shipping lines are increasing the size of the container ships, providing economies of scale. The planned upgrades to Pier four will allow Husky Terminal to handle 2 of the world's biggest ships simultaneously," said Don Johnson, president of the Port of Tacoma Commission. "Today, an estimated 1,500 jobs in Washington State are connected to the movement of cargo through Husky Terminal. These berth enhancements will add capacity, creating the demand for additional family-wage jobs in the region."
In 2013, an investigation performed by the Port of Tacoma showed that the fill material used to create the bulkhead under Pier four was contaminated with TBT.
Developed to be toxic to aquatic life, TBT is a marine biocide, commonly added to ship paint to prevent mollusks from sticking onto vessels and other objects that contain the chemical. E.P.A. canceled all TBT antifouling paint product registrations in December of 2005.
Mollusks are a family of invertebrates that includes clams, oysters, muscles, snails and squid. Extracting the contaminated sediments will help reduce the concentration of TBT in the sediments in the Blair Waterway area to support a healthy and thriving aquatic system and to protect the health of people who eat seafood from the bay.
The Port of Tacoma removed the Pier four deck and pilings between May and August and projects to dredge approximately 40,000 CY of contaminated sediments. The contaminated sediments will be dewatered and trucked to a waste disposal facility. The Superfund phase of the work is expected to be completed by April of 2016 with an overall cost of $19.3 million.
The Port of Tacoma consulted with the Washington Department of Fish and Wildlife and came to the conclusion that dredging would be least harmful to out-migrating fish if dredging started after the beginning of August.
"To minimize the potential for impacts to salmon while dredging the contaminated sediments, we worked with NMFS and WDFW to begin dredging in August to reduce the chances that a work extension would be needed to complete the cleanup when smaller, out migrating juvenile chinook salmon may be present," said Scott Hooton, Port of Tacoma environmental plan manager, "We have also made detailed guidelines for how to operate the clamshell bucket to accurately dredge the required depth and area, as well as making sure the lid is fully secure before lifting through the water to minimize sediment loss."
More details on how the Port of Tacoma projects to reduce the amount of environmental impact the plan will have on the Blair Waterway and surrounding area can be found in Section 5.5.1.2 of the Removal Action Work Plan.
Once the contamination extraction is complete, the Port of Tacoma will begin the 2nd phase of the Blair Waterway extraction and reconstruction. This phase includes additional piling removal, deck demolition, dredging and reconfiguration of the existing pier.
Pier four is located in the Blair Waterway within Commencement Bay, which is a major South Puget Sound waterway. Blair Waterway was formerly a part of the Commencement Bay Nearshore Tideflats Superfund site. Federal, state and local governments spend millions of dollars each year on Puget Sound protection and recovery.
