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A World of Solutions
Lessons Learned from a Rocky Situation: The Story of the
North Topsail Beach Phase 5 Project
Ken Willson
NCBIWA Fall Conference 2015
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• Geologic Setting
• Marine Sand Search / Characterization of the Beach
• Additional Context
• Construction Sequence
• Lessons Learned
Presentation Outline
2 A World of Solutions
Geologic Setting
Town of North Topsail Beach, Onslow County, North Carolina
Project Area
High
Low
3 A World of Solutions
Geologic Setting
Project Area
High
Low
Coastal Change Along the Shore of Northeastern South Carolina:
The South Carolina Coastal Erosion Study
W. A. Barnhardt (Editor)
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Geologic Setting
Rock
Outcrops
Thin Veneer
of Sand Over
Rock
Town of North Topsail Beach, Onslow County, North Carolina
Thin Veneer
of Sand Over
Rock
5 A World of Solutions
2005 and 2006 Offshore Sand Search
– Geophysical Surveys
– Vibracore Surveys
– Cultural Resource Surveys
Sand Search Investigation
Fathometer Magnetometer CHIRP
Seismic Fish
Survey Vessel
Sidescan Sonar Fish
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Final Borrow Area Design
Sand Search Investigation
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Sand Search Investigation
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Sand Search Investigation
Vibracore Investigations
Rock Rock
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Characterization of the Beach
Native Beach: 3,421 Clasts > 3 inches in Diameter in 50,000 ft2 area
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Project 100% LOCALLY FUNDED (No Federal, State, or County* Funds)
USDA Rural Development Loan
Local Government Commission (LGC) approval required
Bidding – Who’s responsible for “unsuitable material”
Permits only allow dredging up to April 30 (Environmental Windows)
Negotiations with low bidder / Decreased mob/demob cost contingent on Town agreeing not to require return the following dredge season (no guaranteed minimum volume)
Additional Context
* County ended up contributing funds after the construction
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Project Overview
Contingency Portion
Of Project
Project Start:
December 18, 2014
No Dredge
Area
Pipeline
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December 18, 2014 at 7:00 P.M. pumping begins.
Construction
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Construction
Early AM December 19, 2014 rocks are first observed in the fill.
Contractor adjusts cutterhead elevation and is able to avoid rock.
Dredging continued with minimal rock until 6:00 AM December 23, 2014 (Christmas Break)
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During Break: Review of vibracore data, geophysical data, extensive coordination with contractor, identify suggested dredge areas, begin discussions regarding methods to handle rock
December 28 – 29, 2014: Dredging resumes, dredge moved to a different location, material has much less rock in it
December 30 – 31, 2014: State and CPE-NC discuss rock concentrations on beach. Conduct an official rock survey
Construction
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Construction
View Looking North At Sta. 750+00
View Looking South At Sta. 748+50
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Construction Continued from Dec. 28th – Jan. 16th with minimal rock contained in the fill.
– Multiple Site Visits by DCM and USACE Representatives
– Coordination regarding rock removal (Town, Engineer, Contractor, NC DCM, and USACE)
January 15, 2015: Town executed a change order with contractor to remove rock (Rock Picker).
January 16, 2015: Higher concentration of rock observed at the discharge.
January 16 – February 6, 2015: Intermittent periods of higher rock discharged. Coordination with DCM and USACE.
February 6, 2015 - Execution of Change Order to Install Rock Boxes.
Construction
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Construction
Rock Picker
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Rock Boxes: Installed
February 12, 2015
Construction
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Mid-February: Rock Picker working, Rock Boxes Installed
Mid-February – Mid-March: Continued monitoring of the beach fill shows intermittent areas with higher concentrations of rock.
March 17, 2015: Multi-Agency Site Visit Conducted to evaluate rock situation
Construction
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Following March 17, 2015 Inter-Agency Site Visit:
Implement Post Hole Digger Monitoring.
Implement Bulk Gravel Analysis.
Hire 3rd Party Contractor (Tigerhole Landscaping) to remediate upper 36 inches of fill
Reduce mesh size of Rock Boxes to 1.5 inches.
Modify Rock Box opperations (No Overflow / Stockpile Proximity).
Officially requested to maintain Rock Box log.
Construction
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Construction
Post Hole Digger – Rock Analysis
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Construction
Bulk Gravel Analysis
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Construction
Remediation of Upper 36” of berm
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Construction
Reduced Mesh Size on Rock Boxes
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April 2, 2015 – USACE orders project to shut down unless a cutterhead screen is installed (USFWS recommendation)
– USFWS agrees to allow work to continue for the evening and then shut down for weather
April 3 – 4, 2015: Contractor Installs cutterhead screen
April 5, 2015: Dredging Resumes w/ Cutterhead screen
Construction
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April 7, 2015 Inter-Agency Site Visit:
Inspect Rock Box Mesh
Inspect Bulk Gravel Analysis.
Inspect 3rd Party Contractor (Tigerhole Landscaping) remediation of upper 36 inches of fill
Inspect Rock Box Emptying /Disposal Operations .
Results of Inter-Agency Site Visit:
Methods being used are resulting in an acceptable beach
Cutterhead Screen can be removed
Continue monitoring
Construction
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Construction
April 7, 2015
USACE Permit Modification
USFWS Formal Consultation
NMFS Informal Consultation
NC DCM Permit Modification
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AGENCIES ARE NOT YOUR ENEMIES!!
Use best available science
Sediment Criteria may require modifications:
– 3 inch clast threshold
– Threshold for Rock in the Borrow Area – Screens
Have contingency plans in place a head of time
Methodology for successfully screening rock
Methodology for monitoring bulk gravel / buried rock
Lessons Learned
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Offshore borrow areas with rock can be used if necessary
Lessons Learned
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Lessons Learned
Offshore borrow areas with rock can be used if necessary
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Lessons Learned
Offshore borrow areas with rock can be used if necessary
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Jan. 1 – March 31
April 1 – June 20
Lessons Learned
Dredge Window Expansion (With Conservation Measures)
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Turtle Monitoring
Benthic Monitoring
Bird Monitoring
Light Survey
2 Nests: Project during construction
2 Nests: Along pipeline during construction
3 Nests: Project after construction (1 Green)
Lessons Learned
Dredge Window Expansion (With Conservation Measures)
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Project Completion
Cooperative Approach to Resolution of Issues (Town, Contractor, Agencies)
Completed Project Within Budget
Constructed a Successful Project (Provide Storm Damage Reduction to homes and infrastructure and a beach environment conducive to natural ecology)
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Comparison of Pre- and Post-Construction Conditions
Project Completion
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Thank You
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