05-9995. Intent to Prepare a Draft Environmental Impact Statement (DEIS) for the Nourishment of 7.25 Miles of Beach, the Repositioning of the New River Inlet Channel, and the Implementation of an Inlet Management Plan, in North Topsail Beach, Onslow ...

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 the Town of North Topsail Beach to nourish approximately 7.25 miles of beachfront to protect residential homes and town infrastructures, and to implement an inlet management plan with the New River Inlet to control the positioning of the inlet channel. The new channel will be centrally located perpendicular to the adjacent shorelines of North Topsail Beach and Onslow Beach. The proposed source of the material for the nourishment will be dredged from offshore borrow area(s) and from the repositioning of the inlet. The placement of beach fill along the Town's shoreline would result in the initial widening of the beach by 50 to 100 feet. The widened beach would be maintained through a program of undefined periodic beach nourishment events with the material extracted primarily from the New River Inlet.

The ocean shoreline in the Town of North Topsail Beach encompasses approximately 11.1 miles along the northern end of Topsail Island. Currently, the U.S. Army Corps of Engineers is developing a Federal shoreline protection plan for parts of North Topsail Beach. This Federal plan will only cover 3.85 miles of the southern part of the beach. The remaining 7.25-miles of North Topsail Beach, with the exception of two small areas, is located within the Coastal Barrier Resource System (CBRS), which prohibits the expenditure of Federal funds that would encourage development. Therefore, the Town is pursuing to develop this non-Federal shoreline protection plan that will preserve existing development and infrastructure along the 7.25 miles of shoreline.

The channel through New River Inlet has been maintained by the COE for commercial and recreational boating interest for over 55 years. The COE is authorized to maintain the channel in the inlet to a depth of 6 feet mean low water (mlw) over a width of 90 feet.

DATES:

A public scoping meeting for the Draft EIS will be held at Dixon High School located on Highway 17, on June 7, 2005 at 6 p.m. Written comments will be received until June 21, 2005.

ADDRESSES:

Copies of comments and questions regarding scoping of the Draft EIS may be addressed to: U.S. Army Corps of Engineers, Wilmington District, Regulatory Division, ATTN: File Number 200500344, 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 Town of North Topsail Beach, located along the north-northeast 11.1 miles of Topsail Island, North Carolina, is proposing to nourish approximately 7.25 miles of beach and reposition New River Inlet channel as a means to address a severe erosion problem that is threatening development and town infrastructure. The entire stretch of the Town's shoreline has experienced a considerable amount of erosion over the last 20 years due primarily to the impact of numerous tropical storms and hurricane during the mid to late 1990's and due to impacts of the uncontrolled movement of the main ebb channel in New River Inlet. The Town has stated that the shoreline erosion and residual effects of the storms have left North Topsail Beach in an extremely vulnerable position with regard to its ocean front development and infrastructure. They have estimated that over $250 million in property tax value as well as roads, water and sewer lines, and other utilities are at risk.

The project area is divided into the North Section and the Central Section

(Note: The South Section is part of the Federal shoreline protection plan). The North Section is further divided into two parts. One comprises approximately 5,800 linear feet, or 1.1 mile, of the project and is located along the northern end of the island. This area will receive material solely from the dredging of the New River Inlet when the channel is repositioned and realigned through the ebb tide delta. The new channel is expected to result in widening of the north of the Town's shoreline as the shoreline responds to the ebb tide delta configuration that would accompany the relocated channel. In addition to the placement of the material in the North Section, a portion of the inlet material will be deposited on the southern end of Onslow Beach as part of the comprehensive inlet management plan in order to maintain the existing sediment budget on Onslow Beach. The second part of the North Section is approximately 14,200 linear feet along the shoreline and will receive sand from the offshore borrow site(s). The Central Section is located both north and south of NC Hwy 210/55 Bridge and is approximately 16,500 linear feet. Material used to widened this section of the beach will also be obtained from the offshore borrow area(s).

2. Proposed Action. The scope of activities for the formulation of the shoreline protection and inlet management plans for the Town of North Topsail Beach includes: (a) Detailed geotechnical investigations to define potential offshore borrow site(s); (b) evaluation and design of a new channel for New River Inlet and the development of an inlet management plan; (c) design and evaluation of beach fill sections including an assessment of the potential impacts of the offshore borrow area(s) on sediment transport; (d) near shore and inlet habitat mapping; and (e) hard bottom investigations. All geospatial data collected for the North Topsail Beach project will be included in a GIS database developed for the project.

Potential offshore borrow areas, previously identified by work conducted by the Wilmington District Corps of Engineers, will be evaluated in detail using jet probes; seismic, sidescan, and magnetometer surveys; as well as vibracores. Samples of the offshore material collected form the jet probes and vibracores will be used to define the preliminary boundaries of the offshore borrow area(s) and make a preliminary determination of the compatibility of the borrow material to the native beach material. The boundaries of the potential borrow area(s) will take into consideration the location and extent of hard bottom resources identified by the sidescan and seismic surveys, as well as in-waters surveys. The boundaries of the proposed offshore borrow site(s) will also be refined to avoid historically significant archaeological artifacts located by the magnetometer surveys and verified through field investigations. Once the boundaries of the potential borrow area(s) are finalized, a final sediment compatibility analysis will be conducted.

The beach fill designs presented in the feasibility study will be refined by analyzing existing profiles to determine potential erosion and storm impacts on back beach features such as vegetation, structures, and infrastructure. Specific designs will be developed for up to five characteristic profiles for the Central and North Sections. Design variations will be considered at discrete beach sections where unique upland features require special accommodation. The composite nature of the final beach and inlet design will require a more complex sequencing in construction operations than normally required for renourishment projects. The method and order of operations will be determined in order to optimize constructability and reduce costs.

Beach planform performance will be evaluated based on the numerical modeling for the proposed projects. The GENESIS numerical model will be used in conjunction with a wave transformation model (STWAVE) to evaluate shoreline positions in time. The wave transformation model will be used to determine changes in wave patterns associated with the near shore borrow area(s). The state-of-the-art GENESIS version will be used so that the project area may be incorporated into a single simulation domain. The historical changes of the project area shoreline will be used to calibrate and verify the model, using an error minimization approach. Adjustments to the wave data used as input within the models will be made as required to replicate observed performance. The GENESIS model will be used to identify optimum alongshore fill placement.

A detailed geomorphic study of New River Inlet was accomplished during the feasibility phase of the project development. The geomorphic study used aerial photographs to evaluate changes in New River Inlet from 1962 and 2003 and develop relationships between the configuration of the New River Inlet ebb tide delta and the behavior of the shorelines on the north end of the North Topsail Beach and the south end of Onslow Beach. The geomorphic study concluded that the most desirable location and orientation of the channel through the ebb tide delta, in terms of impacts on the adjacent islands, is one located closer to North Topsail Beach and oriented essentially perpendicular to the general alignment of the adjacent shorelines. The feasibility phase of the project development also included a preliminary numerical model evaluation of the impact of the relocated channel of flows and flow distributions in the New River Inlet complex.

The next phase of the channel design will include additional numerical model evaluations of a wider range of channel alternatives (channel depths, widths, and locations) and will incorporate modifications in the configuration of the ebb tide delta expected to occur in response to the new channel. The reconfigured ebb tide delta will also be used to determine the potential changes in wave patterns north and south of New River Inlet and the impacts these changes could have on longshore sediment transport and shoreline behavior.

The potential shoaling characteristics of the new channel will be evaluated using empirical shoaling algorithms developed for inlets in North Carolina. The propensity of the new channel to migrate to the north and/or south and possible future changes in the channel alignment will be based on observed changes in New River Inlet as documented by the geomorphic analysis. The potential changes in longshore sediment transport patterns on North Topsail Beach and Onslow Beach associated changes in wave patterns together with the channel shoaling analysis will be used to develop a with-project sediment budget. The with-project sediment budget will be compared to the existing sediment budget to determine sand bypassing requirements that would be needed to maintain the existing sediment budget of the adjacent islands.

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

a. Potential impact to marine biological resources (benthic organisms, passageway for fish and other marine life) and Essential Fish Habitat, particularly Hard Bottoms.

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

c. Potential impacts to water quality.

d. Potential increase in erosion rates to adjacent Onslow Beach.

e. Potential effects on military training on U.S. Marine Corps Camp Lejeune Base.

f. Potential impacts to Navigation, commercial and recreational.

g. Potential impacts to the long-term management of New River Inlet.

h. Potential impacts to private and public property.

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

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

k. Potential impacts on public health and safety.

l. Potential impacts to recreational and commercial fishing.

m. The compatibility of the material for nourishment.

n. Potential economic impacts.

4. Alternatives. Several alternative borrow areas 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, and with the National Marine Fisheries Service under the Magnuson-Stevens Act and Endangered Species 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 projects 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 early 2006, and a public hearing will be held after the publication of the Draft EIS.

Dated: May 12, 2005.

George T. Burch,

Chief of Staff.