a world of solutions north topsail beach shoreline protection project phase 1 – new river inlet...

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

2A World of Solutions

TopicsTopics

1.Location

2.Purpose

3.Problem Identification

4.Design

5.Construction

6.Preliminary Monitoring Results


LocationLocation


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


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.


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)


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)


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.


Design Process – Influence of New River InletDesign Process – Influence of New River Inlet

New River Inlet 1988 (Photo courtesy of Dr. Bill Cleary, UNCW)



New River Inlet 2005 Alignment (Photo courtesy of the USACE)



Existing Ebb Tide Delta

Reconfigured Ebb Tide Delta


Construction ProcessConstruction Process

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


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.


Construction Process - AccomplishmentsConstruction Process - Accomplishments

North Topsail Beach – Post Construction (March 20, 2013)



Pre-ConstructionNovember 17, 2012

Post ConstructionJanuary 30, 2013



Pre-ConstructionNovember 23, 2012

Post ConstructionJanuary 30, 2013


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).


DiscussionDiscussion

Robert NealCoastal Planning & Engineering, Inc.

A CB&I [email protected]

(910) 791-9494

a world of solutions north topsail beach shoreline protection project phase 1 – new river inlet...

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