The U.S. Army Corps of Engineers, Portland District, is proposing to perform maintenance dredging of two federal navigation channels in Oregon State: Tongue Point and Oregon Slough.
The purpose of the proposed action is to facilitate safe and reliable navigation, said USACE. Congress has authorized construction and maintenance of the two navigation channels at various times.
According to USACE, the channels would be maintained to authorized depths using clamshell, mechanical, or pipeline dredges.
Tongue Point will be maintained to the authorized depth of 34 feet, and Oregon Slough to the authorized depth of 20 feet. All channels may be dredged to an additional depth of 2 feet greater than the authorized depths for advance maintenance, said USACE.
They plan to place the dredged materials in the Columbia River from River Mile (RM) 3 to RM 105.5 where water depth is 20 feet or greater.
USACE said that the work will occur from August 1 through December 15. Frequency of dredging for Tongue Point is anticipated to be annually; frequency of dredging for Oregon Slough is anticipated to be 1 out of 5 years.
Typical volume of material proposed for removal varies, ranging from 800,000 cubic yards for initial deferred maintenance, then decreasing to approximately 119,000 CY for Tongue Point, and as needed for Oregon Slough.
The deadline for submitting the comments on this plan is October 28, 2021.