The U.S. Army Corps of Engineers, Seattle District, recently began routine maintenance dredging of portions of the Duwamish Waterway to remove approximately 63,500 cubic yards of shoaled material from three sections within the federal channel in the waterway.
The Corps awarded the contract to American Construction Co. of Tacoma, Wash., for $733,500.The work should be complete by Jan. 31.
The dredging is performed using a 5-cubic-yard clamshell bucket and approved dredging procedures designed to minimize sediment resuspension and remove the material. The contractor is starting in the turning basin and will remove approximately 28,000 cubic yards. In a segment in the upper channel, immediately downstream of the turning basin, approximately 34,000 cubic yards will be removed and in a segment in the lower channel, near the Spokane Street bridge, approximately 1,500 cubic yards.
Sediment from the Duwamish River is deposited throughout the channel, reducing the channel availability to waterborne traffic. Routine maintenance dredging is conducted every two years to remove shoaling that builds up, allowing vessel traffic to transit the federal channel safely.
Corps officials worked with the EPA, Washington Departments of Ecology and Natural Resources, Port of Seattle and Muckleshoot Indian Tribe to ensure the dredging was environmentally responsible. In addition, the Corps prepares a biological evaluation in accordance with the Endangered Species Act and assures full compliance with the act prior to starting.
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Press Release, January 2, 2014