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North Topsail Beach Shoreline Protection Project

North Topsail Beach Shoreline Protection Project Phase 1 – New River Inlet Channel Realignment & Beach Restoration NC Water Resources Congress October 31, 2013. Robert Neal Coastal Planning & Engineering, Inc. A CB&I Company. Topics. Location Purpose Problem Identification Design

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North Topsail Beach Shoreline Protection Project

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  1. North Topsail Beach Shoreline Protection Project Phase 1 – New River Inlet Channel Realignment & Beach Restoration NC Water Resources Congress October 31, 2013 Robert Neal Coastal Planning & Engineering, Inc. A CB&I Company

  2. Topics • Location • Purpose • Problem Identification • Design • Construction • Preliminary Monitoring Results

  3. Location

  4. Purpose Realign New River Inlet and Place Beach Material Along the Shoreline to Provide Storm Protection and Erosion Mitigation to North End of North Topsail Beach • Re-focusing the inlet will cause the creation of the ebb shoal offshore of North Topsail Beach • Ebb shoal creation will provide a buffer to absorb storm and wave energy • Ebb shoal creation in conjunction with sand placement will reduce erosion stress along northern tip of the island by closing marginal flood tide channel • Sand placement will increase beach width and mitigate erosion stress along with providing storm protection for project shoreline beyond the influence of New River Inlet

  5. Problem Identification North Topsail Beach has been susceptible to damage created by coastal storms and long term erosion trends. • Damage from Hurricane’s Bertha and Fran (1996) estimated at $72 million from several hundred homes, including mobile homes, being destroyed. • Areas fronted by a ‘wide beach and more significant dune system’ received minor damages compared to the majority of North Topsail Beach. • Long-term erosion influenced by the alignment of New River Inlet has also left the shoreline vulnerable to damages.

  6. Problem Identification – Storm Damage Northern Area of North Topsail Beach, Post Hurricane Fran – Sept. 1996. (Photo courtesy of Dr. Bill Cleary, UNCW)

  7. 23rd Ave 24th Ave Problem Identification – Storm Damage Southern Area of North Topsail Beach, Post Hurricane Fran – Sept. 1996. (Photo courtesy of the USACE)

  8. Problem Identification – Long Term Erosion North Topsail Beach Shoreline Change (1963 to 1983 & 1983 to 2002) Rates are based on USACE developed rates from 1963 to 1983 and 1963 to 2002.

  9. Design Process – Influence of New River Inlet New River Inlet 1988 (Photo courtesy of Dr. Bill Cleary, UNCW)

  10. Design Process – Influence of New River Inlet New River Inlet 2005 Alignment (Photo courtesy of the USACE)

  11. Existing Ebb Tide Delta Reconfigured Ebb Tide Delta Design Process – Influence of New River Inlet

  12. Construction Process North Topsail Beach – Immediately Prior to Construction (Nov. 2012)

  13. Construction Process Alterations to the Design were Required due to Limited Material Available from New River Inlet & Storm Impacts from Hurricane Sandy and other Coastal Systems • Realignment of New River Inlet ocean bar channel (Removal of approx. 600,000 cyds) • A 4 foot high dune with a crest width of 15 feet created along northern most 1,700 feet of North Topsail Beach. • Average fill density totaled approximately 73 cy/lf. • Minor modifications made to the dune in southern project area. • Project length shortened by 2,000 feet to maximize sand placement in front of ocean front structures.

  14. Construction Process - Accomplishments North Topsail Beach – Post Construction (March 20, 2013)

  15. Construction Process - Accomplishments Post Construction January 30, 2013 Pre-Construction November 17, 2012

  16. Construction Process - Accomplishments Post Construction January 30, 2013 Pre-Construction November 23, 2012

  17. Preliminary Monitoring Results The Town of North Topsail Beach Established a Monitoring Program to Document Shoreline Performance and the Evolution of the Ebb Shoal • Shoreline measurements show a more material 6 months after construction compared to immediately following construction (results skewed due to USACE maintenance of AIWW). • Beginning stages of ebb shoal evolution appear promising (5 to 15 year time period estimated for full development).

  18. Discussion Robert Neal Coastal Planning & Engineering, Inc. A CB&I Company Robert.Neal@cbi.com (910) 791-9494

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