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Charleston HarborABSTRACT:  Charleston Harbor is located in Charleston, South Carolina at the confluence of the Cooper, Ashley, and Wando rivers.  It is strategically located in one of the fastest growing regions of the United States and the project has been identified as a critical infrastructure project under the President’s “We Can’t Wait” Initiative. The South Carolina State Ports Authority (SCSPA) is the non-Federal sponsor.

The need for modifications to the existing navigation system in Charleston Harbor is generated by physical constraints and the associated inefficiencies that limit the system’s ability to safely and efficiently serve the forecasted vessel fleet and process the forecasted cargo volumes.

The project area includes the offshore entrance channel, inner harbor channels and offshore and landside dredged material disposal sites.  Alternative plans combined multiple structural and nonstructural measures to improve the safety and efficiency of the existing navigation system.  Three main types of problems were be addressed: insufficient Federal channel depths, difficult currents, and restrictive channel widths and turning basins.

The Recommended Plan is a Locally Preferred Plan, which is 2 feet deeper and approximately $45 million more costly than the NED Plan. It proposes the following improvements as summarized below:

•  Deepen the existing entrance channel from a project depth of -47 feet to -54 feet mean lower low water (MLLW) and extend it about three miles seaward from its current position to reach compatible depths
•  Deepen the existing entrance channel from a project depth of -47 feet to -54 feet mean lower low water (MLLW) and extend it about three miles seaward from its current position to reach compatible depths
•  Deepen the inner harbor from an existing project depth of -45 feet to -52 feet MLLW to the Wando Welch container facility and the New Navy Base Terminal and -48 feet MLLW for the reaches above the New Navy Base Terminal to the North Charleston Terminal
•  Enlarge the existing turning basins to an 1800-foot diameter at the Wando Welch and New Navy Base Terminals and widen selected areas to accommodate Post Panamax Generation 2 and 3 vessels and enlarge the North Charleston Terminal turning basin to a 1650-foot diameter and widen selected areas to accommodate Post Panamax Generation 2 vessels
•  Place dredged material and raise dikes at the existing upland disposal facilities at Clouter Creek, Yellow House Creek, and Daniel Island; place material dredged from the lower harbor at the Ocean Dredged Material Disposal Site and expand the site; and Place rock to create hardbottom habitat near the entrance channel as a least cost and beneficial use of dredged material.
•  Mitigation includes creation of 29 acres of hardbottom habitiat; preservation of about 665 acres of wetlands to offset indirect wetland impacts from saltwater intrusion; and environmental and shoreline erosion monitoring.

The Recommended Plan is economically justified. It would generate about $80,900,000 of net average annual economic benefits to the nation at a benefit-to-cost ratio of 3.89 to 1 at a 3.375% discount rate. At October 2014 price levels, the estimated project first costs for authorization purposes (the cost of local service facilities are not included) are $493,300,000 with $224,300,000 Federal share and $269,000,000 non-Federal share (including the 100% non-Federal LPP increment). It is estimated that the project will increase the annual O&M requirements by approximately 830,500 cubic yards, primarily from the expansion of the two turning basins, with an associated annual O&M cost increase of approximately $3,740,000.

REPORT DOCUMENTATION:  Pertinent documentation on the project, the results of the Civil Works Review Board, and subsequent Washington-Level Review Actions are listed below (items not linked will be provided when available):
ADDITIONAL INFORMATION: