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Title: Environmental Assessment and Finding of No Significant Impact (FONSI) : Morehead City Harbor, Federal Navigation Project, Navigation Corridor
Authors: United States. Army. Corps of Engineers. Wilmington District.
Keywords: Morehead City (N.C.)
Dredging spoil
Channels (Hydraulic engineering)
Environmental management
Environmental protection
Publisher: United States. Army. Corps of Engineers. Wilmington District.
Abstract: The purpose of the proposed project is to address maintenance dredging challenges at Beaufort Inlet, which will improve the navigability and safety for commercial vessels calling on the Port of Morehead City. The Morehead City Harbor navigation project is considered a geographically fixed channel and Wilmington District has historically maintained the Morehead City Harbor in accordance with this determination. The dynamic nature of Beaufort Inlet and the high shoaling rates have resulted in significant increases in maintenance dredging costs and dredging feasibility challenges. The shoaling in Beaufort Inlet creates critical pinch points within the channel. The shoaling area that continually poses a maintenance and navigation challenge is the Shackleford Banks spit located on the east side of Range A and the Cutoff. Based on a shoaling rate analysis completed in 2013, the Shackleford Banks spit was moving west into the navigation channel at approximately 250 feet per year. In 2015, the navigation channel was restricted to depths between 5’ to 28’ across the entire authorized width in the vicinity of the Shackleford Banks spit. Hydrographic surveys performed in 2017 continue to show the Shackleford Banks spit extending into the authorized navigation channel. The 2017 bathymetric survey showed navigable depth has been significantly reduced from -45 feet mean lower low water (MLLW) to areas as shallow as -7.0 feet MLLW within the authorized navigation channel. In order to consistently provide a navigable channel at Morehead City Harbor, a maintenance dredging plan that more closely follows natural deep water is needed. The most current channel survey data can be found on the Wilmington District USACE website at: Beaufort-Harbors/ . Maintaining this section of the channel, and therefore providing safe navigation, has become extremely challenging with such a rapid shoaling rate and limited project funding. Additionally, the slope of the material within the channel is extremely steep at nearly 3H: 1V, so traditional dredge plants, such as hopper dredges, are unable to adequately remove the shoal. The only dredge plant with the capability to remove the steep, expansive shoal is a large ocean certified pipeline dredge, which has a much higher cost for mobilization and cost per cubic yard to remove material from the channel. Under current project funding levels, this type of dredge is a fiscal possibility about once every 3 years. For this reason, the full project dimensions cannot be achieved or maintained, which results in ship traffic being forced to follow the deeper water west of the channel, outside the existing authorized footprint. This creates a difficult condition for transiting vessels, as successful navigation of the channel requires vessels to execute a precise “S-turn” as they pass between Shackleford Banks and Bogue Banks, in the portion of the channel with highest current velocities. A commercial cargo ship, the Pola Palekh, ran aground in Beaufort Inlet on November 17, 2016. This led the U.S. Coast Guard to close the entire Morehead City Harbor navigation project to deep draft commercial traffic. The purpose of the proposed project is to take advantage of the natural deep water route, thereby reducing maintenance dredging quantities and dredging costs, and improving navigation for commercial, deep draft vessels calling on the Port of Morehead City.
Description: Environmental Assessment and Finding of No Significant Impact
Rights: Approved for Public Release; Distribution is Unlimited
Size: 169 pages / 23.66 MB
Types of Materials: PDF
Appears in Collections:Environmental Documents

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