a world of solutions north topsail beach shoreline protection project phase 1 – new river inlet...
TRANSCRIPT
A World of Solutions
North Topsail Beach Shoreline Protection ProjectNorth Topsail Beach Shoreline Protection Project
Phase 1 – New River Inlet Channel Realignment & Beach RestorationPhase 1 – New River Inlet Channel Realignment & Beach Restoration
NC Water Resources CongressNC Water Resources Congress
October 31, 2013October 31, 2013
Robert NealRobert Neal
Coastal Planning & Engineering, Inc.Coastal Planning & Engineering, Inc.
A CB&I CompanyA CB&I Company
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TopicsTopics
1.Location
2.Purpose
3.Problem Identification
4.Design
5.Construction
6.Preliminary Monitoring Results
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LocationLocation
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PurposePurpose
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
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Problem IdentificationProblem 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.
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Problem Identification – Storm DamageProblem Identification – Storm Damage
Northern Area of North Topsail Beach, Post Hurricane Fran – Sept. 1996. (Photo courtesy of Dr. Bill Cleary, UNCW)
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Problem Identification – Storm DamageProblem Identification – Storm Damage
24th Ave
23rd Ave
Southern Area of North Topsail Beach, Post Hurricane Fran – Sept. 1996. (Photo courtesy of the USACE)
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Problem Identification – Long Term ErosionProblem Identification – Long Term Erosion
-30
-25
-20
-15
-10
-5
0
5
10
15
550+00 600+00 650+00 700+00 750+00 800+00 850+00 900+00 950+00 1000+00 1050+00 1100+00 1150+00 1200+00
Baseline Stations
Sh
ore
line
Ch
ang
e R
ate
(ft/
yr)
1963 to 1983 1983 to 2002
-0.9 ft/yr -4.9 ft/yr -0.6 ft/yr-4.9 ft/yr -0.6 ft/yr
-19.7 ft/yr
-2.2 ft/yr
-0.9 ft/yr
-1.6 ft/yr
-4.9 ft/yr
-1.8 ft/yr
-0.6 ft/yr
-19.7 ft/yr
+6.4 ft/yr
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.
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Design Process – Influence of New River InletDesign Process – Influence of New River Inlet
New River Inlet 1988 (Photo courtesy of Dr. Bill Cleary, UNCW)
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Design Process – Influence of New River InletDesign Process – Influence of New River Inlet
New River Inlet 2005 Alignment (Photo courtesy of the USACE)
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Design Process – Influence of New River InletDesign Process – Influence of New River Inlet
Existing Ebb Tide Delta
Reconfigured Ebb Tide Delta
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Construction ProcessConstruction Process
North Topsail Beach – Immediately Prior to Construction (Nov. 2012)
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Construction ProcessConstruction 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.
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Construction Process - AccomplishmentsConstruction Process - Accomplishments
North Topsail Beach – Post Construction (March 20, 2013)
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Construction Process - AccomplishmentsConstruction Process - Accomplishments
Pre-ConstructionNovember 17, 2012
Post ConstructionJanuary 30, 2013
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Construction Process - AccomplishmentsConstruction Process - Accomplishments
Pre-ConstructionNovember 23, 2012
Post ConstructionJanuary 30, 2013
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Preliminary Monitoring ResultsPreliminary 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).
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DiscussionDiscussion
Robert NealCoastal Planning & Engineering, Inc.
A CB&I [email protected]
(910) 791-9494