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Title: Detailed Project Report and Environmental Assessment : Manteo, Old House Channel, NC, Section 204 Project
Authors: United States. Army. Corps of Engineers. Wilmington District.
Keywords: Dredging
Dredged material
Pamlico Sound (N.C.)
Environmental management
Environmental protection
Publisher: United States. Army. Corps of Engineers. Wilmington District.
Abstract: This Detailed Project Report and Environmental Assessment (EA) presents the findings regarding the Manteo, Old House Channel, NC Section 204 Project, and documents the plan formulation process and potential environmental effects associated with the implementation of oyster reef restoration alternatives for the proposed site. The geographic scope of this study consists of an approximately 17-square-mile Project Study Area, the center of which is located in northeastern North Carolina, within Pamlico Sound and Dare County, approximately 13 miles south-southeast of Manteo, NC and 4.5 miles southwest of Oregon Inlet. Range 2 of Old House Channel runs through the middle of this area, and is part of the Manteo (Shallowbag Bay) Federal Navigation Project. The overall goal of the Manteo, Old House Channel, NC Section 204 Project is to improve oyster reef habitat that has been in historical decline in Pamlico Sound, through the beneficial use of dredged material from Old House Channel. In 2008 the State of North Carolina responded to indicators signaling potential further decline of the Pamlico system and its oyster populations by enacting new State coastal stormwater rules to protect and improve water quality. The State also requested the USACE (Corps) to investigate opportunities for oyster restoration in the Pamlico system, indicating a willingness and financial capability to execute a project partnership agreement (PPA) should a detailed project report be approved. This project would contribute to the State’s oyster restoration goals in the northern Pamlico Sound in conjunction with the Corp’s operational dredging and disposal needs for Old House Channel. This report summarizes baseline existing conditions in the study area, as well as projected future conditions without the project. It also develops and discusses potential solutions as a guide to Federal and non-Federal involvement in the restoration project. This report provides a description and discussion of the likely array of alternative plans, including their benefits, costs, and environmental effects and outputs. This report also identifies, evaluates, and recommends a solution (the Tentatively-Selected Plan) that best meets the planning objectives of oyster habitat restoration and beneficial uses of dredged material within the study area. The Tentatively-Selected Plan (oyster reef construction) involves use of dredged material from maintenance dredging of Old House Channel to restore habitat by building submerged sand islands to be topped with cultch for oyster reef restoration. Containment of sand for the submerged islands would be accomplished using stone. Based on the cost effectiveness/incremental cost analysis of these options, the best-buy plan would be a complex of four stone containment structures, each enclosing a 5.07-acre reef. However, the best-buy plan has an estimated cost of $8,393,000 and would exceed the federal costshare limit of the Section 204 authority of $5,000,000. The Tentatively-Selected Plan (TSP) is therefore the most cost-effective alternative with a federal cost within the cost-share limit. The TSP is composed of three stone containment structures, each enclosing a 5.07-acre reef. The Total Project Cost for implementation of the TSP would be $7,217,000 including the fully Federally funded feasibility costs of $453,000. For cost sharing purposes, the total design and implementation phase costs are estimated at $6,763,000, the same amount shown in the draft PPA (annex 12 of this package). Resultant Federal and non-Federal cost shares are $4,396,000 (65%) and $2,367,000 (35%), respectively. The period of analysis used to compute costs is 50 years with a FY12 federal interest rate of 4.0%. This Tentatively-Selected plan would provide restoration benefits of 32.3 average annual habitat units (AAHU) at an average annual cost f $329,429, which results in an average annual cost per AAHU of $10,199. The non-Federal sponsor fully supports the Tentatively-Selected Plan.
Description: Detailed Project Report and Environmental Assessment
Rights: Approved for Public Release; Distribution is Unlimited
Size: 392 pages / 33.22 MB
Types of Materials: PDF
Appears in Collections:Environmental Documents

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