07-848. Intent To Prepare a Draft Environmental Impact Statement (DEIS) for the Development of an Inlet Management Plan That Includes the Repositioning and Realignment of the Main Ebb Channel of Rich Inlet and To Use the Material To Nourish Figure ...

AGENCY:

Department of the Army, U.S. Army Corps of Engineers, DoD.

ACTION:

Notice of intent.

SUMMARY:

The U.S. Army Corps of Engineers (COE), Wilmington District, Wilmington Regulatory Field Office has received a request for Department of the Army authorization, pursuant to Section 404 of the Clean Water Act and Section 10 of the Rivers and Harbor Act, from Figure “8” Beach Homeowners Association to develop a management plan for Rich Inlet that would mitigate chronic erosion on the northern portion of Figure Eight Island so as to preserve the integrity of its infrastructure, provide protection to existing development, and ensure the continued use of the oceanfront beach along the northernmost three miles of its oceanfront shoreline. Figure Eight Island is an unincorporated privately developed island located on the southeast coast of North Carolina, approximately eight miles north of Wilmington. The island is bordered to the south by Mason Inlet and Wrightsville Beach; and to the north by Rich Inlet and Lea-Hutaff Island, an undeveloped, privately-owned island.

The inlet management plan would involve the repositioning and realignment of the main ebb channel of Rich Inlet to a location closer to the north end of Figure Eight Island. The intended alignment is to be essentially perpendicular to the oceanfront shorelines of the adjacent islands. The new channel position would be periodically maintained with maintenance episodes dictated by natural shifts in the channel position that produce unfavorable shoreline responses on the north end of Figure Eight Island. While the main focus of the project is to relocate the main ebb bar channel, consideration will also be given to possible alterations in Nixon Channel and Green Channel to determine if such modification would enhance the stability of the new channel. Nixon Channel meanders along a southwesterly path on the landward side of the north end of Figure Eight Island; connecting to the Atlantic Intracoastal Waterway (AIWW) at a point approximately two miles west of the Rich Inlet throat. Green Channel meanders to the northeast on the landward side of Lea-Hutaff Island and intersects with the AIWW approximately 1.75 miles north of the Rich Inlet throat.

Material dredged from the inlet and channels will be placed along the central and northern portions of Figure Eight Island and, if needed, along portions of Lea-Hutaff Island. The objective of the placement of beach fill along the Figure Eight Island's shoreline is to keep the design fill density less than 50 cubic yards/foot, to avoid the placement of a permanent static vegetation line. This beach fill would be maintained through a program of periodic beach nourishment events with the material extracted from the dredging of Rich Inlet to maintain the inlet in an optimum location.

DATES:

A public scoping meeting for the Draft EIS will be held at Eaton Elementary School, located at 6701 Gordon Road, on March 1, 2007 at 6 p.m. Written comments will be received until March 29, 2007.

ADDRESSES:

Copies of comments and questions regarding scoping for the Draft EIS may be addressed to: U.S. Army Corps of Engineers, Wilmington District, Regulatory Division. ATTN: File Number 2006-41158-067, Post Office Box 1890, Wilmington, NC 28402-1890.

FOR FURTHER INFORMATION CONTACT:

Questions about the proposed action and DEIS can be directed to Mr. Mickey Sugg, Wilmington Regulatory Field Office, telephone: [phone].

SUPPLEMENTARY INFORMATION:

1. Project Description. The Figure Eight Beach Homeowners Association proposes to develop an inlet management plan for Rich Inlet that will produce semi-permanent positive shoreline impacts on the extreme north end of Figure Eight Island. Through a variety of investigations, it has been determined that chronic erosion problems along the northern sections of Figure Eight Island have been directly linked to changes in the orientation and position of the main ebb channel through Rich Inlet. When the main ebb channel of the inlet is oriented toward the southeast or in the direction of Figure Eight Island, and positioned close to the north end of the island, the shoreline immediately south of the inlet tends to accrete. The accretion is associated with the wave sheltering (“breakwater effect”) provided by the south side of the ebb tide delta which also moves with the channel. During periods in which the main bar channel migrates to the north toward Lea-Hutaff Island and is oriented in a southeasterly direction, the north end of Figure Eight Island erodes. The northward movement of the main ebb channel is accompanied by the northward shift of the south side of the ebb tide delta away from the north end of Figure Eight Island, thus removing the “breakwater effect” afforded by the south side of the ebb tide delta.

A geomorphic analysis of Rich Inlet will be performed utilizing historical aerial photographs of Rich Inlet and the adjacent shorelines. The geomorphic analysis will be used to develop alternative channel positions and alignments that will assist in determining the desired changes on the north end of Figure Eight Island. The analysis will also assist in identifying any positive and/or negative impacts associated with Lea-Hutaff Island. The position and alignment of the main ebb channel design and design alternatives will be evaluated to determine the potential effects on the adjacent shorelines and natural resources located within the study area.

2. Proposed Action. The scope of activities for the formulation of the management plan for Rich Inlet will include the following engineering and geological investigations: (1) Detailed geomorphic studies of the inlet and its impacts on the shorelines of Figure Eight Island and Lea-Hataff Island; (2) numerical model simulations of various channel alternatives including possible modifications of Nixon and Green channels; (3) geotechnical investigations to determine sediment quality in the inlet and connecting channels; (4) compatibility analysis of the inlet material with the native beach material; and (5) and analysis of the physical impacts of the project on the inlet complex (including the adjacent marshes and connecting channels) and on Figure Eight Island and Lea-Hutaff Island.

The Figure Eight Island beach fill design will consist of the disposal material from Rich Inlet channel along the island shoreline in a general template of a horizontal berm constructed to an elevation of +6.0 feet NAVD (National Geodetic Vertical Datum) with a 1V:15H seaward slope. The width of the berm, which would begin near the seaward toe of the existing dune system, will depend on the volume of material removed from Rich Inlet to construct the new channel and the slope the material assumed during placement. Another design objective is to keep the design fill density less than 50 cubic yards/foot, to avoid the placement of a permanent static vegetation line. The volume of material that would be removed to construct the new channel will depend on the final design of the channel but could range between 500,000 cubic yards and 2,000,000 cubic yards. Some of the channel material may be used to construct or maintain the dune system on portions of Figure Eight Island. Existing profiles will be analyzed to identify the range of natural beach and dune elevations, widths, and slopes. The beach fill design will include beach fill construction templates and equilibrium cross-sections to estimate the seaward limit of cross-shore spreading over the project life and the reduction in beach width due to changes in profile shape following construction.

Beach planform performance will be evaluated based on the numerical modeling for the proposed projects. The numerical model evaluation of various channel alternatives will employ a process-based numerical model known as Delft3D developed by WL Delft Hydraulics (WL Delft Hydraulics, 2005). Delft3D is an advanced 2D/3D hydrodynamic model that can simulate water level changes, currents, wave transformation, sediment transport, and bathymetric (morphological) changes in coastal environments. The model evaluations will consider short-term changes (i.e., tidal cycles and storms) to the inlet's flow pattern and morphology; as well as long-term (one to five years) changes in flow patterns and inlet morphology associated with various inlet channel alternatives. The model simulations will also be used to evaluate the importance of modifications of Nixon and/or Green Channels on the overall stability and associated impacts of the new channel.

Comprehensive geotechnical investigations of the Rich Inlet system including the inlet throat, flood tidal delta, ebb tidal delta, and feeder channels Nixon and Green Channel will be used to identify and map sand quality and quantity to be placed on the shoreline of Figure Eight Island or elsewhere as the study dictates. The proposed sand search will be completed in two phases: (1) Research and planning, and (2) jet probes and vibrance collection and analysis. Sand resources in the study area will be evaluated for compatibility with native beach sand. This evaluation is necessary to determine the potential performance of sand on the beach since the performance is highly dependent on similar sediment characteristics including mean grain size, sorting, and composition of borrow sands and native sands.

The research and planning phase includes a comprehensive analysis of historical geophysical data, hydrographic survey data, and aerial photographs of the inlet to determine potential channel shall lag deposit sites and historic preferred channel alignment. The jet probe survey will provide preliminary qualitative information of the sediment contained in the feeder channels and the ebb tide delta of Rich inlet. Areas suspected of containing the best quality and quantity of sand resources within the preferred channel realignment corridor will be targeted for vibracore investigation.

A magnetometer survey was performed on September 3, 2006 on the wreck site of the Wild Dayrell. The Wild Dayrell is a side-wheel steamer which ran aground near in the Rich Inlet complex on February 3, 1864. The location of the Wild Dayrell and its debris field will play a major role in options associated with the location of the new inlet channel. In addition, a cultural resource study of the final borrow area and channel design will be performed using a magnetometer survey controlled by differential global positioning. Cartographic and historical research will be conducted to collect available historical data.

Natural resource studies and investigations which may be conducted in support of the plan formulation might include: (1) Identification and biological characterization of estuarine habitat types (salt march, shelfish, submerged aquatic vegetation) in a defined project area using aerial mapping and/or groundtruth investigations; (2) pre-project monitoring of threatened and endangered species and their associated habitats as determined through coordination with project stakeholders; and (3) development and/or implementation of project monitoring and mitigation plans based on the project impact assessment.

3. Issues. There are several potential environmental issues that will be addressed in the EIS. Additional issues may be identified during the scoping process. Issues initially identified as potentially significant include:

a. Potential impacts to marine biological resources (benthic organisms, passageway for fish and other marine life) and Essential Fish Habitat, particularly within Green Channel.

b. Potential impacts to threatened and endangered marine mammals, birds, fish, and plants.

c. Potential impacts to water quality.

d. Potential increase in erosion rates to adjacent Lea-Hutaff.

e. Potential impacts to Navigation, commercial and recreational.

f. Potential impacts to the long-term-management of Rich Inlet.

g. Potential impacts to private and public property.

h. Cumulative impacts of Inlet and Inlet channel relocations throughout North Carolina.

i. Cumulative impacts for using inlets as sand source in nourishment projects.

j. Potential impacts on public health and safety.

k. Potential impacts to recreational and commercial fishing.

l. The compatibility of the material for nourishment.

m. Potential impacts to cultural resources, particularly the Wild Dayrell shipwreck.

4. Alternatives. Several alternatives are being considered for the proposed project. These alternatives will be further formulated and developed during the scoping process, and an appropriate range of alternatives, including the no federal action alternative, will be considered in the EIS.

5. Scoping Process. A public scoping meeting (see DATES) will be held to receive public comment and assess public concerns regarding the appropriate scope and preparation of the Draft EIS. Participation in the public meeting by federal, state, and local agencies and other interested organizations and persons is encouraged.

The COE will also be consulting with the U.S. Fish and Wildlife Service under the Endangered Species Act and the Fish and Wildlife Coordination Act; with the National Marine Fisheries Service under the Magnuson-Stevens Act and Endangered Species Act; and with the North Carolina State Historic Preservation Office under the National Historic Preservation Act. Additionally, the EIS will assess the potential water quality impacts pursuant to Section 401 of the Clean Water Act, and will be coordinated with the North Carolina Division of Coastal Management (DCM) to determine the project's consistency with the Coastal Zone Management Act. The COE will closely work with DCM through the EIS to ensure the process complies with all State Environmental Policy Act (SEPA) requirements. It is the COE and DCM's intentions to consolidate both NEPA and SEPA processes to eliminate duplications.

6. Availability of the Draft EIS. The Draft EIS is expected to be published and circulated sometime in 2008, and a public hearing will be held after the publication of the Draft EIS.

Dated: February 12, 2007.

John E. Pulliam, Jr.,

Colonel, U.S. Army District Commander.