Sediment Compatibility forBeach Nourishment in North

Carolina

Gregory L. Williams, Ph.D., P.E.Chief, Coastal, Hydrology & Hydraulics SectionUSACE Wilmington District

US Army Corpsof EngineersWilmington District

Tri-Services Infrastructure ConferenceSt. Louis, MO3 August 2005

Wilmington District

CharlotteCharlotte

WilmingtonWilmington

ManteoManteoGreensboroGreensboro

AshevilleAsheville

RaleighRaleigh

MoreheadCity

MoreheadCity

RoanokeRoanoke

Atlantic

Ocean

Atlantic

Ocean

VAVANCNC

SCSC

WashingtonWashington

Carolina BeachCarolina Beach

Kure BeachKure BeachBrunswick CountyBeaches

Brunswick CountyBeaches

Dare County:Bodie IslandDare County:Bodie Island

Constructing Shore ProtectionConstructing Shore ProtectionKureKure Beach, NCBeach, NC

Bogue BanksBogue Banks

Wrightsville BeachWrightsville Beach

US Army Corpsof EngineersWilmington District

Topsail BeachTopsail BeachN. Topsail /Surf CityN. Topsail /Surf City

Hatteras &Ocracoke

Hatteras &Ocracoke

B.E. JordanReservoir

B.E. JordanReservoir

Falls Dam &Reservoir

Falls Dam &ReservoirW. Kerr Scott

Dam & ReservoirW. Kerr Scott

Dam & Reservoir

J.H. Kerr Dam &Reservoir

J.H. Kerr Dam &Reservoir

Philpott Dam& Reservoir

Philpott Dam& Reservoir

OregonInlet

OregonInlet

Problem/IssueAtlantic Beach, NC Pine Knoll Shores Shell Hash

2002

Emerald Isle Carbonate2003

Oak Island Sea Turtle Habitat2001

What does “compatible” mean?

• North Carolina– Sand used for beach nourishment shall be compatibleshall be compatible

with existing grain size and type

• Florida– Borrow from navigation channels 10% fines– Borrow from other sources 5% fines

• USACE– Any borrow material 10% fines– Default criteria accepted through coordination with

resource agencies

≤

≤

≤

NC State Agencies• Division of Coastal Management (DENR)

– Coastal Area Management Act (CAMA) of Federal CZM Act– Using rules and policies of Coastal Resources Commission– Permitting/enforcement, CAMA land use planning, et al.

• Coastal Resources Commission– Establishes policies for the Coastal Management Program– Adopts rules for CAMA– Designates Areas of Environmental Concern (AEC)– Adopts rules and policies for coastal development within AECs

and certifies local land-use plans

• Science Panel on Coastal Hazards– Technical experts advising DCM– Provides CRC with scientific data and recommendations

pertaining to coastal topics

Science Panel on Coastal HazardsScience Panel on Coastal Hazards

• Dr. John Fisher, ChairNC State University

• Dr. Margery OvertonNC State University

• Dr. Orrin PilkeyDuke University

• Dr. Stan RiggsEast Carolina University

• Dr. Bill ClearyUNC Wilmington

• Mr. Tom JarrettConsultant (Retired USACE)

• Mr. Steve BentonRetired DCM

• Mr. Spencer RogersNC Sea Grant

• Dr. Pete PetersonUniversity of North Carolina

• Dr. John WellsVirginia Institute of Marine Science

• Dr. Greg WilliamsUSACE Wilmington District

Proposed Criteria1. General Definitions

2. Characterization of Beach to be Nourished

3. Characterization of Borrow Site Material

4. Compatibility of Borrow Site Material toBeach to be Nourished

5. Execution of Nourishment Project

6. Monitoring and Mitigation

Definitions

• Beach nourishment• Borrow area• Sand resource• Sand reserve• Compatibility• Sediment• Grain size

Beach Characterization

• Sediment sampling to geological and engineering standardscapturing 3-D spatial variability of sediment characteristics

• Minimum of 3 evenly spaced (not exceeding 5,000 ft), shore-perpendicular transects

• Sampling locations to follow morphology – half of total samplestaken landward of MLW, half seaward of MLW and one at MLW

• Average grain size, fine grained fraction (<0.0625 mm) and coarsegrained fraction (>4.76 mm) calculated by simple arithmetic meanof all samples collected

• For prior nourished beaches use best available data• Beach sediment characterization fixed for future

Sampling Protocol for beach

MHW

MLW

Shor

efac

e(N

ears

hore

)

Dun

e To

e

Mid

ber

m

Mea

n H

igh

Wat

er

Bar

Fron

tal D

une

Cre

st

Trou

gh

subaerial submarine

Mid

tide

Mea

n Lo

w W

ater

Borrow Site Characterization

• Use appropriate acoustic and/or equivalent remotely sensedbathymetric and subsurface survey techniques

• Sampling methodology shall use a core barrel of no lessthan 3 inches (76.2 mm) in diameter

• No characterization and sampling required from a regularlymaintained navigation channel*

• Fine- (<0.0625 mm) and coarse-(>4.76 mm) grainedfraction determined by a simple arithmetic mean of allsamples collected

Borrow site sampling

Compatibility—Size

• The average percentage by weight of the fine-grainedfraction (<0.0625 mm) of borrow material shall notexceed average percentage by weight of native beachfines plus 5%– e.g., 6% native plus 5% = 11% threshold

• The average percentage by weight of the coarse-grainedfraction (>4.76 mm) of borrow material shall notexceed average percentage by weight of native beachcoarse material plus 4%– e.g., 6% native plus 4% = 10% threshold

Compatibility—Mineralogy

• Composite mineralogy shall be similar, specificallycarbonate content that shall not exceed 40% over theaverage percentage by weight of the native beach. (Thistopic warrants further investigation.)

– e.g., 25% CO3 on native beach plus 40% = 65% threshold

• Sandy sediment from navigation channel maintenance shallnot exceed 10% percentage by weight of fine-grainedmaterial (<0.0265 mm) regardless of native beach content

• Be consistent with the Submerged Lands Mining Rules

• Not alter wave refraction patterns resulting in adverseimpacts to adjacent shoreline(s)

• Not alter inlet hydrology resulting in increased erosionor an adverse impact ecosystems or habitat

• Be done in a manner consistent with State policyregarding habitat protection

• Not contain foreign material (construction debris, toxicmaterial, etc.)

Project ExecutionProject Execution

• Material placement shall not violate water qualitystandards

• Exceedingly coarse material (>64 mm) greater than pre-nourished values shall be removed in an environmentallysound manner

• Biological and physical monitoring data shall be used todesign biological and ecological mitigation whereimpacts are sufficient to require it

• Goal of scientific monitoring to better understandbiological and physical response to beach nourishmentand decrease adverse impact(s)

Monitoring & MitigationMonitoring & Mitigation

• Review formal recommendations fromCRC Science Panel on Coastal Hazards

• New scientific data?

• Stakeholder input

• Analysis of how recommendations anddraft rules will affect the “real world”

Implementation Process

OAKISLANDNATIVE

0.86

4.71

0.72

3.15

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

#4 #200

Sieve Mesh Size

perc

ent

USACEDCM

COARSE LIMITS

USACE = none

DCM = native + 4%

= 4.72%

Florida = 5%

FINE LIMITS

USACE = 10%

DCM = native + 5%= 8.15%

Florida = 5%Perc

ent R

etai

ned

(#4)

or P

assi

ng (#

200)

HOLDENBEACHNATIVE

0.56

3.4

0.54

2.27

0

0.5

1

1.5

2

2.5

3

3.5

4

#4 #200

Sieve Mesh Size

percentUSACEDCM

COARSE LIMITS

USACE = none

DCM = native + 4%= 4.54%

Florida = 5%

FINE LIMITS

USACE = 10%

DCM = native + 5%= 7.27%

Florida = 5%Perc

ent R

etai

ned

(#4)

or P

assi

ng (#

200)

• Impacts of these criteria (or somevariation) is not yet known• DCM staff goal is little/no impact to beach

nourishment

• DCM goal is to be as compatible with USACE aspossible

• White paper is being prepared by DCM

• Final DCM recommendations to go toCRC this fall

Conclusions

Questions?

Gregory L. Williams, Ph.D., P.E.Chief, Coastal, Hydrology & Hydraulics SectionUSACE Wilmington DistrictP.O. Box 1890Wilmington, NC 28402910-251-4767greg.l.williams@saw02.usace.army.mil