2019-04-10 Minutes
10 April 2019
Meeting Minutes
Chairman Barbour called the Port, Waterway & Beach Commission (PWBC) meeting to order at
~4:00. Participant introductions were made; attendance sheet is attached. The March
2019 meeting minutes were approved.
Presentation: Carolina Beach (CB), Refined Coastal Modeling (RCM)
Robert Neal, PE.
Goals: Corroborate US Army Corps of Engineers (USACE) design template.
Assess template placement and volume alternatives.
Evaluate 4-year alternatives providing equal infrastructure protection.
Assess economic risks following a 15-year maintenance hiatus.
The Fiscal Year (FY) 2019 coastal storm damage reduction (CSDR) project maintenance event and
ongoing annual shoreline mapping will allow opportunities to evaluate Pleasure Island modeling
results. Each beach community received a copy of RCM reports. Kure Beach (KB)
results will be presented at the May PWBC meeting.
Current Efforts
CB and KB FY 2019 CSDR Projects:
Awaiting USACE confirmation, Weeks Marine completed the CB CSDR reaches on 12 March 2019
placing an estimated quantity of 1,060,552 cubic yards. Awaiting USACE confirmation, Weeks Marine
has completed the KB North reaches with a target volume of 412,000 cubic yards. Weeks Marine has
a target start date of 8 April for KB South reaches with a target volume of 460,000 cubic yards. Weeks
targeted completion date is 3 May.
On 22 March, Prime Policy organized a DC delegation staff project site visit. Congressman Rouzer,
Senator Burr and Senator Tillis staffers participated in the project tour.
Atlantic Intracoastal Waterway (AIWW) Maintenance Dredging Contract:
The Wrightsville Beach Coast Guard Station was completed on/about 7 April. The Shinn Creek
crossing was started but curtailed following an issue with the spillway system. The contractor has
moved to the Mason Creek crossing with a revised template volume of ~33,000 cy; sediment
management is in confined disposal facility 241.
Mason Inlet Relocation Project (MIRP):
The 2019 annual engineering surveys as well as the bi-weekly waterbird management area surveys
have begun. A 2019/2020 relocation event will be assessed following surveyed template volumes.
Target goals include beneficial placement on Figure 8 and the inclusion of WB North. The WB North
concept would demonstrate an island-wide capability, a supplemental effect on the Moores Inlet Drive
hot spot and further assessment of Mason Inlets sediment movement influence.
Carolina Beach Inlet (CBI):
The next maintenance event was scheduled for around April 14; the available dredge plant is the
Murden. Since the meeting, resource agency approvals have been received for the out of window
th
use of the inshore dredge material management site and the Murden began work on the 15. This
is a proposed ten-day event with an estimated cost of $260,000.00 leaving an inlet maintenance fund
balance of $760,000.00. Following the event, the USCG is anticipated to restore the buoy alignment
and remove the navigation restriction.
WB, Post Authorization Change Report (PACR); CB, Beach Renourishment Evaluation Report
(BRER):
The Coastal Barrier Resource Act (CBRA) continues as a borrow site challenge. A USACE
conference call rolling out the tentative selected plan is scheduled for 25 April. The Wilmington
Districts approach is to retain the existing borrow sites CBRA notwithstanding.
Public Comment:
CB Councilman Shuttleworth noted he has fielded many concerns regarding placement volumes and
locations along the rock revetment. The concerns are the USACE placed less than in previous
maintenance events and the current project will not provide the protection and access as in past
years.
Carolina Beach Refined Coastal Modeling
April 10, 2019
Carolina Beach Refined Coastal Modeling
Goals
Evaluate Potential Local Management Strategies for CB CSDR
Project in case Federal Participation Falters
Estimate Economic Risks Following a 15-Year Maintenance
Suspension
Assess Material Placement & Volumetric Alternatives for
Locally Managed CSDR Project
Evaluate 4-Year Alternatives for Providing Equal or Greater
Infrastructure Protection
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Carolina Beach Refined Coastal Modeling
Process
Evaluate Current CSDR Placement Limits & Quantities to Determine if
Enhanced Project Performance May Be Provided Through Design
Adjustments.
Uses GenCade, Delft3D, & SBEACH to Estimate Project Performance and
Storm Level of Protection Benefits
Delft3D –Focuses on Sediment Transport & Morphologic Changes
Influenced by Long-term Coastal Processes
GenCade –Evaluates Shoreline Recession & Longshore Transport
Based on Multi-Year Wave Patterns
SBEACH –Estimates Cross-Shore Storm Induced Erosion Expected in
Extreme Weather Events
3
Modeling Approach
USACE CB CSDR Material Placement Limits & Recent Usage
4
Shoreline Recession –15 Year Maintenance
Suspension
Estimated Structural Value Impacted
5
Modeling Approach
Carolina Beach Reference Monuments
6
Shoreline Recession –15 Year Maintenance
Suspension
7
Shoreline Recession –15 Year Maintenance
Suspension
8
Shoreline Recession –15 Year Maintenance
Suspension
9
Shoreline Recession –15 Year Maintenance
Suspension
10
Shoreline Recession –15 Year Maintenance
Suspension
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Carolina Beach Refined Coastal Modeling
DesignAlternatives 1 -7
Assumed Engineered Borrow Area (IDMMS) Would Remain the
Primary Sand Source (Recharge Rate of 250,000 cy/yr)
Potential Template Alternatives
Alt 1: USACE Template (CB01 –CB16) –674,000 CY
Alt 2: Reduced Template(CB01 –CB16) –323,200 CY
Alt 3: USACE Authorized CSDR Limits (CB01 –CB20) –382,500 CY
Alt 4: USACE 50-Ft Width Extension (CB01 –CB16) –810,000 CY
Alt 5: Feeder Approach (CB01 –CB16) –655,400 CY
Alt 6: Modified 25-Ft Width Extension (CB01 –CB16) –725,700 CY
Alt 7: 25/75-Ft Width Extension (CB01 –CB16) –925,700 CY
*Volumes shown are based on the 2015 shoreline conditions.
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Carolina Beach Refined Coastal Modeling
DesignAlternatives 1 -7
CB Southern Municipal CB Northern Municipal
BoundaryBoundary
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Carolina Beach Refined Coastal Modeling
Alternatives Maintained the USACE Recommended Dune & Storm Berm Features.
Only the Construction Berm Width Varied.
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Carolina Beach Refined Coastal Modeling
Design Alternatives Average Construction Berm Widths
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Carolina Beach Refined Coastal Modeling
Sediment Transport (Delft3D Analysis)
Estimated Volume Remaining (CB01 to CB20)
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Carolina Beach Refined Coastal Modeling
Shoreline Recession (GenCade Analysis)
Estimated Shoreline Width Remaining (Individual Reference Monuments)
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Carolina Beach Refined Coastal Modeling
Cross-shore Response to Storm Activity (SBEACH Analysis)
Estimated Level of Protection (LOP) Provided For a 2-Yr, 5-Yr, 10-Yr, 25-Yr,
50-Yr, & 100-Yr Storm Event
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Carolina Beach Refined Coastal Modeling
Annualized Economic Benefit
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Carolina Beach Refined Coastal Modeling
Overall Modeling Summary/Conclusions:
Model Results Indicate Alt 7 (25/75-Ft Extension) should:
Provide a 4-Yr maintenance interval with an annual savings
(benefit) of $118,045 (2016).
Retains a greater material volume Year 4 than Alt 1
(USACE) provides through Year 3.
Create an average 7-Ft shoreline extension and maintain the
same LOP (25-Yr Storm Event) as Alternative 1 (USACE)
across the CSDR project area throughout the maintenance
interval.
Modeling also corroborated Alternative 1 (USACE) as aviable
alternative for a locally managed CSDR project under a 3-yr
maintenance period.
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Carolina Beach Refined Coastal Modeling
Thank you!
Questions / Discussion
Robert Neal, PE
Moffatt & Nichol
Ph: 910.218.7100Email: rneal@moffattnichol.com
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Agenda
10 April 2019, 4:00 PM
New Hanover County, Government Center
Finance Conference Room, 500
4:00 Call to Order
Welcome/Introductions
Request approval of the March meeting minutes (emailed 15 March 2019).
Presentation
: Carolina Beach, Refined Coastal Modeling presented by Moffatt & Nichols Robert Neal, PE.
Abbreviated Current Efforts:
Carolina Beach (CB) and Kure Beach (KB) Fiscal Year (FY) 2019 Coastal Storm Damage Reduction (CSDR) Projects
On 12 March Weeks Marine completed the CB CSDR project reaches; Weeks began CB on 16 February.
Weeks began offshore on 23 March to KB North and anticipates transitioning to KB South on or before 8 Apr
with a 3 May project completion target.
On 22 March, delegation staffers toured the CB and KB project sites.
Atlantic Intracoastal Waterway (AIWW) Maintenance Dredging Contract
Southwinds schedule is tentatively the WB Coast Guard Station and then the Shinn Creek AIWW crossing.
The Mason Creek AIWW crossing is anticipated following these two reaches.
Mason Inlet Relocation Project (MIRP)
The annual upland and bathymetric surveys have begun.
Carolina Beach Inlet (CBI)
The next maintenance event is scheduled around mid-April; the available dredge plant has not been
determined.
Use of the inshore dredge material management site is being coordinated with the resource agencies.
The US Coast Guard will lift the (28 March) notice to mariners following the maintenance event and their inlet
buoy relocations.
WB, Post Authorization Change Report (PACR)
The Coastal Barrier Resource Act (CBRA) continues as a borrow site challenge.
A USACE conference call rolling out the tentative selected plan is scheduled for 25 April.
CB, Beach Renourishment Evaluation Report (BRER)
The CBRA continues as a borrow site challenge; A USACE conference call rolling out the tentative selected
plan is scheduled for 25 April.
Public Comment:
Adjourn