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Title: Interim Final Integrated Feasibility Report and Environmental Assessment : Coastal Storm Damage Reduction General Investigation Study, Edisto Beach, Colleton County, South Carolina
Authors: United States. Army. Corps of Engineers. Charleston District.
Keywords: Edisto Beach (S.C.)
Shore protection
Environmental management
Environmental protection
Publisher: United States. Army. Corps of Engineers. Charleston District.
Abstract: This Integrated Feasibility Report and Environmental Assessment presents the results of studies performed to examine the feasibility of federal coastal storm damage reduction for the Town of Edisto Beach, South Carolina. It describes baseline conditions, the formulation and evaluation of alternative plans and the identification of a Recommended Plan. Edisto Island is a barrier island located at the mouth of the South Edisto River in Colleton County, South Carolina, approximately 45 miles southwest of Charleston, South Carolina and approximately 20 miles east-northeast of Beaufort, South Carolina. Edisto Beach encompasses approximately 6 miles of sand shoreline, all of which were included in the feasibility study. The primary goal of the study is to reduce the adverse economic effects of coastal storms at Edisto Beach. Six action alternatives and the no action alternative were evaluated and compared in order select and recommend an alternative. The action alternatives included: 1. Mid-size dune and berm fill combined with 1,090 ft of groin lengthening 2. Minimum size dune and berm fill combined with 360 ft of groin lengthening 3. Maximum size dune and berm fill combined with 1,970 ft of groin lengthening 4. Mid-size dune and berm fill combined with 1,130 ft of groin lengthening 5. Dune sand fencing on some reaches with dune and berm fill on other reaches 6. Non-Structural/Demolition (over limited reaches) The mid-size dune and berm fill combined with 1,130 ft of groin lengthening alternative (number 4 above) generated the highest net economic benefits and was selected as the recommended plan. The primary features of the Recommended Plan include: - A 15-foot high, 15-foot wide dune beginning at the northern end of the project and extending southward along the beach for 16,530 feet. This dune would be fronted by a 7-foot high (elevation) berm. The first 7,740 feet of berm length would have a width of 75 feet. The width would taper to a 50-foot width over the remaining length of the berm. The width of each end of the berm would taper to match the existing beach profile. - Beginning at the southern end of the 15-foot high dune, the dune would transition to a 14-foot high, 15-foot wide dune and extend around the end of the island for 5,290 feet. No berm would be constructed in front of this dune because the existing beach profile provides an adequate berm. - Approximately 1,130 ft of groin lengthening across 23 of the existing groins. - 16-year renourishment interval. It is worth noting that the Edisto Beach State Park was initially a part of the study area. However, it was not included in the Recommended Plan because of a lack of existing infrastructure needed to generate enough benefits to justify the cost to protect that portion of beach. Based on 2014 price levels, the initial construction cost of the project is $21,129,000, and the renourishment cost that is expected to occur every 16 years is $10,914,000, with the present value totaling $16,030,800. The interest during construction is approximately $106,800 and operations and maintenance approximately $83,000. The total expected average annual coastal storm damage reduction benefits (at 3.5% interest rate) for the Recommended Plan are estimated to be $2,849,000. The average annual recreation benefits are $573,200. The Environmental Assessment and Finding of No Significant Impact were distributed in August 2013 for a 30 day comment and review period. The Final Environmental Assessment addresses the comments received during this review period. The findings demonstrate that the proposed project will not significantly adversely affect environmental resources or human health, the preparation of an Environmental Impact Statement is not warranted.
Description: Feasibility Report and Environmental Assessment
Rights: Approved for Public Release; Distribution is Unlimited
Size: 839 pages / 52.6 MB
Types of Materials: PDF
Appears in Collections:Environmental Documents

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