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Volume 74 Number 2 Spring 2006

ORGANIZED 1926 EIGHTIETH YEARSHORE & BEACH is published four times per year by the American Shore & Beach Preservation Association,

ASBPA, 5460 Beaujolais Lane, Fort Myers, Florida 33919-2704. The views expressed and the data presented by the contribu-

tors are not to be construed as having the endorsement of the Association, unless specifically stated. SHORE & BEACH is

a refereed journal.

Shore & Beach Website: http://www.asbpa.orgClaims for missing issues should be made to the Membership Office.

Such claims will be honored up to six months after publication.

American Shore & Beach Preservation Association is a tax-exempt non-profit organization under a tax exemptionletter from the commissioner of the Internal Revenue Service, September 14, 1950. Articles appearing in this journal

are indexed inENVIRONMENTAL PERIODICALS BIBLIOGRAPHY. - ISSN 0037-4237ASBPA makes no representation or warranty regarding the accuracy, truth, quality, suitability or

reliability of information or products provided by any third-party sponsors, exhibitors, authors orpresenters associated with any ASBPA-affiliated event, publication or Web site.

CONTENTS

EDITORIAL 2Reinhard E. Flick

OBSERVATION AND IMPLICATIONS OF LONG WAVESIN ST. JOSEPH BAY, FLORIDA

David D. McGehee, P.E., M.Oc.E.

BEACH NOURISHMENT EXPERIENCE IN THE UNITED STATES:STATUS AND TRENDS IN THE 20THCENTURY

Charles W. Finkl, Lindino Benedet, and Thomas J. Campbell

HERON ISLAND, GREAT BARRIER REEF, AUSTRALIAHubert Chanson, Reader

SAND BACK-PASSING WITH LAND-BASED EQUIPMENT,A COST-EFFECTIVE APPROACH FOR BEACH RESTORATION

Stuart Chase, P.E.

GREEN TURTLE (CHELONIA MYDAS L.) POPULATION ESTIMATEFOR THE NEARSHORE REEFS OF BROWARD COUNTY:A SUMMARY AFTER THREE YEARS OFPRE-CONSTRUCTION MONITORING

Christopher Makowski1, Lou Fisher2and Craig J. Kruempel1

BIOLOGICAL COMMUNITY ANALYSIS NEAR A MAINTAINEDNATURAL INLET

Erin A. Hague and Robert M. Baron

THE NON-MARKET VALUE OF BEACH RECREATION IN CALIFORNIALinwood Pendleton, Associate Professor, Judith Kildow,

James W. Rote, Distinguished Professor,

NORTH STRADBROKE ISLAND, MORETON BAY, AUSTRALIAHubert Chanson, Reader

Cover:Wreck of HMCS Protector, built in 1884, sunk in 1943, and now protecting the shore against erosion onHeron Island on the Great Barrier Reef, Australia. Photo by H. Chanson, 27 December 2001.

PRESIDENT:

Mayor Harry Simmons Caswell Beach, North CarolinaVICE PRESIDENTS:

Thomas Campbell, P.E. Boca Raton, Florida Anthony P. Pratt Dover, Delaware Gerard Stoddard New York, New York Supervisor Tom Wilson Santa Ana, CaliforniaSECRETARY:

Russell Boudreau Long Beach, CaliforniaTREASURER:

Brad Pickel Santa Rosa Beach, FloridaDIRECTORS:

Steve Aceti, J.D. Encinitas, California David Basco, Ph.D. Norfolk, Virginia Noreen Bodman Sandy Hook, New Jersey Michael Bruno,Ph.D. Hoboken, New Jersey* David Cannon Long Beach, California Ralph Cantral Washington, D.C. Michael Chrzastowski, Ph.D. Champaign, Illinois George W. Domurat Pacifica, California Scott Douglass, Ph.D. Mobile, Alabama Lesley Ewing San Francisco, California Deborah Flack Tallahassee, Florida Douglas Gaffney Cherry Hill, New Jersey Steve Higgins Fort Lauderdale, Florida James R. Houston, Ph.D. Vicksburg, Mississippi Tim Kana, Ph.D. Columbia, South Carolina Nicholas C. Kraus, Ph.D. Vicksburg, Mississippi Council member Ann J. Kulchin Carlsbad, California John Lee Dickinson, Texas James Leutze, Ph.D., Wilmington, North Carolina

D.T. Minich, Fort Meyers, Florida* Jerry Mohn Galveston, Texas Mayor Robert E. Pinkerton, Jr. South Padre Island, Texas Joan Pope Alexandria, Virginia Jim Rausch Washington, D.C. Greg Reid Oakland, California Thomas W. Richardson Vicksburg, Mississippi Phillip Roehrs Virginia Beach, Virginia Gregory Rudolph Emerald Isle, North Carolina* Charles Shabica, Ph.D. Chicago, Illinois Supervisor Pam Slater-Price San Diego, California Kim Sterrett Sacramento, California Mayor Gary Vegliante West Hampton Dunes, New York Michael P. Walther, P.E., Vero Beach, Florida Howard Marlowe, Legislative Coordinator Washington, D.C. Kate & Ken Gooderham, Exec. Directors Fort Myers, Florida

* By virtue of being a chapter presidentADVISORY BOARD:

Robert Dean, Ph.D., Chuck Hamilton, Syed Khalil, Stephen P.Leatherman, Ph.D., Orville Magoon, Ram Mohan, Ph.D., P.E.,

Joe Moseley, Ph.D., Patricia Newsom, William Stronge, Ph.D.DIRECTORS EMERITI:

Charles L. Bretschneider, Paul Dennison, Thorndike Saville,Jr., George M. Watts, Henry M. von Oesen, Robert L. Wiegel

EDITOR:

Reinhard E. Flick, Ph.D. La Jolla, California E-mail: [email protected] ASSISTANT:

Amy Hsiao E-mail to: [email protected] EDITORS:

Thomas J. Campbell, Boca Raton, FL Michael J. Chrzastowski, Champaign, IL Lesley C. Ewing, San Francisco, CA Nicholas C. Kraus, Ph.D., Vicksburg, MS Holley Messing Editorial Assistant

EDITORIAL OFFICE: Reinhard E. Flick, Ph.D. c/o Scripps Institution of Oceanography 9500 Gilman Drive La Jolla, CA 92093-0209 E-mail manuscripts to: [email protected] OFFICE:

Address all membership dues, remittances, changes of address,and advertising correspondence to:

Ken and Kate Gooderham, publishers ASBPA, 5460 Beaujolais Lane Fort Myers, Florida 33919-2704 Phone: (239) 489-2616, Fax: (239) 489-9917 E-mail: [email protected] COORDINATION:

Yancy Young, 2596 Spyglass Drive, Suite A, Shell Beach, CA 93449-1764 Phone: (805) 773-0077, E-mail:[email protected]


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Shore & Beach Vol. 74, No. 2, Spring 2006, pp.2

From the Editors Desk

By

Reinhard E. Flick

2

An interesting thing is happening

on the way to producing Shore &Beach: we actually have a back-log of papers! This is welcome news fora publication that has often had a papershortage (look at issues of 12 or 15 yearsago and notice the bigger font size), in-cluding in 2004 and 2005, after I took overas editor from Nick Kraus. It may resultin a little longer wait to see your paper inprint. But it will also mean that we canbe more selective, and publish only betterquality papers.

Even more than money and volunteertime Shore & Beach needs papers - lots

and lots of paper submissions. We thank

those of you who have encouraged contri-

butions and assembled issues, especiallyTom Campbell and Lindino Benedet, andLesley Ewing and Joan Pope, recent-vol-ume guest editors. We especially thankthose of you who have contributed ar-ticles! Please continue to consider Shore &

Beach for your technical publishing.

We also welcome your letters and opin-ion pieces. Surely, there is something nag-ging you about coastal management, or acontroversial technical point in one of thepapers, or even some disagreement withan editorial point that you just cant resistcommenting on!

In this issue we present an assortment of

papers covering several of the disciplinesimportant to coastal activities. These in-clude beach economics (Pendleton andKildow), wave erosion (McGehee), sandmanagement engineering (Chase), thetechnical history of beach nourishment(Finkl, Benedet, and Campbell), construc-tion monitoring (Makowski, Fisher, andKruempel), and the scenic beauty and cul-tural significance of it all (Chanson).

Thank you all for your continued inter-est in, support of, and contributions toShore & Beach. Please keep those paperscoming!


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Observation and Implications of Long Waves in

St. Joseph Bay, Florida

By

David D. McGehee, P.E., M.Oc.E.Emerald Ocean Engineering LLC

Pensacola Beach, [email protected]

ABSTRACT

A section of Floridas St. Joseph Peninsula isexperiencing significant erosion. If it breaches,a new inlet into St. Joseph Bay will result. Waterlevels were measured inside, near the entrance,and outside of the bay to understand the hydrody-namic processes governing the bay system and tocalibrate and verify a numerical hydrodynamic cir-culation model for predicting impacts. Long waveswere observed during a frontal passage at sub-tidalfrequencies with amplitudes that exceeded themean tidal range. The phase lag of one componentbetween the outside and the inside of the bay at the

potential breach site was near 180 degrees, result-ing in a larger hydraulic head than tidal analysisalone would predict. Potential impacts includerapid growth of the inlet, beyond the equilibriumsize, during certain meteorological events (includ-ing hurricanes), and introduction of water withmuch higher sediment loads discharged from adja-cent Apalachicola Bay into St. Joseph Bay.

ADDITIONAL KEYWORDS: Erosion, breach,inlet, long waves, seiche, phase lag, scour sus-pended sediment Paper Received: 20 June 2005,

Revised and Accepted: 6 March 2006.

BACKGROUND

St. Joseph Bay, FL, is an embaymentlocated on the northern shore of theGulf of Mexico situated between

the mainland and St. Joseph Peninsula, acurving sand spit with the prominent CapeSan Blas located at its southern corner(Figure 1). The bay entrance opens to thenorthwest and is sheltered from directoffshore wave energy. Tides in the Gulf ofMexico to the east of Cape San Blas aremixed, while those west of the Cape arepredominantly diurnal (FDEP 2000). The

tide in St. Joseph Bay is diurnal with amean range of about 1.5 ft. In recent history the peninsula has expe-

rienced significant long term and episodicerosion along its western side the highesthistorical shoreline erosion rate in the state(Coastal America 1996). State Road 30Eruns along St. Joseph Peninsula and pro-vides routine access and the only evacua-tion route for the residents of the peninsulaand visitors to the St. Joseph PeninsulaState Park. A segment of roadway neara site called Stump Hole is particularlythreatened, and is currently protected bya rock revetment (Figure 2). One of the

options being considered by the FloridaDepartment of Transportation is to allowthe breach to occur naturally and replacethat section of roadway with a bridge be-hind the resulting inlet.

Measured water level time series at vari-ous sites in and around the bay are neededto understand the hydrodynamic processesgoverning the bay and to calibrate and ver-ify a numerical hydrodynamic circulationmodel (ADCIRC) of the system (Chen

2005). This paper describes the collection,analysis, validation and implications ofthat data set of water level time series.

DATA COLLECTION

Three sites were selected to define theimportant hydraulic characteristics of thesystem: Site 1, in the Gulf, offshore ofStump Hole; Site 2, in the bay, just northof Stump Hole; and Site 3, near the en-trance to St. Joseph Bay (Figure 3).

Water level time series were measuredat each site using self-contained waterlevel gauges with internal battery powerand solid-state memory. The gauges mea-sure and record ambient water pressure(absolute) and temperature at a program-mable sampling scheme. The followingparameters resulted in a battery-limitedoperational life of about two weeks:

Sample Rate 2 HzSample Length 450 sec = 7.5 minSample Interval 10 min.

The gauges software saved the aver-age of the nine hundred samples overthe sample length. Thus, a data pointrepresents the mean of the 2 Hz samplesof water pressure (and temperature) overa 7.5-minute interval, and there were sixdata points retained every hour.

Gauge mounts were fabricated fromPVC pipe to avoid galvanic corrosion ofthe stainless steel instrument housings andminimize weight. To discourage tampering

Figure 1. Map of region and project studyarea.

Figure 2. Aerial photo of Stump Hole andendangered section of roadway.

Figure 3. Map showing project gage sites(xs) and area tide and met stations (os).


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from the curious, the top of the housing

was attached by cement, sealing the instru-

ment inside. Removal of the instrument

required sawing the main housing apart

after recovery.

A 2-in diameter by 5-ft long PVC pipe

piling extended from the bottom of each of

the main housings (Figure 4). A removable

2-in diameter deployment pipe could be

threaded into the top of the main housing;

a 2-in diameter hose with control valve

was attached to the top end of this pipe. Todeploy the mount, a portable pump forced

water through the removable pipe, around

the annular space between the gauge and

the main housing, and out through the

lower piling. Using the control valve to

regulate the water flow, the pipe piling was

jetted into the sand until the lower end of

the main housing was at or below the level

of the seabed. For additional support, the

main housing was attached to adjacent pil-

ings using heavy-gauge nylon cable ties.

After installation, the deployment pipe

was unscrewed, exposing the pressure sen-

sor to ambient water pressure. Recovery

was by reversing this process.

The goal of the deployment was to

obtain a minimum of three days of data

over a spring tidal cycle. Figure 5 shows

the predicted tide at Port St. Joe inside St.

Joseph Bay, and Figure 6 shows the mea-

sured winds at SGOFI1, a meteorological

station located on an offshore platformabout 20 nm SSE of Cape San Blas, dur-ing the first two weeks of March 2005. Thedeployment interval is highlighted.

A frontal passage brought moderate to

strong northwest winds the first few daysof the month. Winds stayed between 10and 20 knots from the northeast betweenMarch 3 and 4, and then veered morenortherly on March 5 as a mild cold frontpassed through. Gauges were deployedon March 6. Two gauges, a primary andredundant were placed at Sites 2 and 3.The redundant gauge mount at Site 1 wasdamaged during placement, so only theprimary gauge was deployed. A strong

cold front reached thearea late on March 7

the rapid wind shiftto the north aroundmidnight is obvious.Winds peaked at 35kt as the front passedand remained above20 kt for the next 24

hours. While the gauges could have oper-ated for at least another week, the brief lullthat presented itself between the afternoonof March 9 and the morning of March10 seemed an opportunity for recovery

worth grabbing. Just after retrieval of thelast gauge, winds picked up and stayedabove 12 kt nearly continuously for thenext week, including the third front in twoweeks.

The gauges horizontal position was de-termined to about +10 ft with a differentialGPS receiver. Elevations were determinedfrom an optical level on shore by reading agraduated rod placed on the top of the gagethrough the opening in the top of the mainhousing. That level was then referencedto the nearest benchmark to provide the

elevation of the top of the gage relative toNGVD. Table 1 summarizes the deploy-ment parameters at the three sites.

DATA ANALYSIS

Data Reduction

Measured absolute ambient pressure wasconverted to gage pressure by subtract-ing atmospheric pressure, obtained fromSGOF12. Measured gage pressure is di-rectly proportional to water depth by wayof seawater density, which is a functionof water temperature and salinity. Watertemperature was measured by the gages - it

remained between 16 and 20 Cat all sites-- but salinity had to be assumed. A conver-sion factor 2.25 ft/psi was used to producethe water depth time series for each gage.Water depth was converted to water surface

Figure 4. Gage mount with fixed pile anddeployment pipe ready for installation.

Figure 5. Predicted Tides at Port St. Joe,March 1- 14, 2005.

Table 1. Gage Deployment Sites

Table 2. Linear Spatial Trends of Datums and Datum Differences for Regional TidalStations

Figure 6. Plot of the measured winds in the area, March 114,2005.

Footnotes

1A 24-hour data gap beginning 0900 on March 9 was filled with data fromApalachicola Airport.

2A 24-hour data gap beginning 0900 on March 9 was filled with data fromApalachicola Airport.


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elevation relative to NGVD by adding themeasured elevation of each gage.

DATUM ADJUSTMENT

In the following sections, the projectdata set will be compared to both mea-

sured and predicted time series from tidalstations established by the National OceanService (NOS). NOS tide gage data aretypically archived relative to a local Da-tum of Tabulation, so all data (NOS 2005)was adjusted to NGVD. This required es-tablishing adjustments at each tide stationbetween NGVD, NAVD and local MLLW.The results are provided in Table 2; theseare the recommended values for transfer-ring the project water level time seriesdata, as referenced to NGVD, to eitherNAVD or MSL. Note that the adjustmentis provided to only one decimal place - fur-

ther resolution is unjustified. Details of theanalysis process, which included evalua-tion of the change in the rate of sea levelrise within the Northwest Florida region,are found in McGehee (2006).

Data Validation

The reduced data were subjected to qual-

ity control/quality assurance procedures,including comparisons between primaryand redundant gages and comparisons toadjacent NOS tide gages. A minor surveydiscrep3ency was identified and corrected.The final uncertainty of the measured water

levels is approximately + 0.05 ft. Details ofthe validation process are found in McGe-hee (2006). Figure 7 plots the final qualifieddata from the three measurement sites.

DISCUSSION

A notable aspect of the signal at allthree project sites, as well as at PanamaCity Beach, is the prevalence of inter-mediate oscillations between wind waveperiods (order of seconds to tenths of asecond) and tidal periods (order of a halfto full day). These oscillations, calledlong waves, can be generated directly by

forces of sufficient size and scale, suchas meteorological features, e.g.: fronts, orindirectly from non-linear interactions be-tween incident and reflected wind waves,wind waves of different periods, or windwaves and currents. Continuation of theoscillations beyond one or two cyclesindicates that the frequency of the forcing

energy is near resonance with the naturalfrequency of oscillation, or sloshing, ofone or more nearby basins. These reso-nant oscillations (including subharmonics)are called seiching, and will occur in St.Joseph Bay, as well as any area defined

by a sudden change in depth, such as theoffshore shoals, the bights to either sideof the cape, even the continental shelf.Even when their amplitudes are small (onthe order of inches), the horizontal watervelocities associated with long waves canhave significant impacts (McGehee 1991).

While long waves are usually detect-able at most ocean sites, the persistenceand amplitude of these harmonics at thissite are fairly unusual. This weather eventgenerated long waves inside the bay onthe order of 1 ft, comparable with tidalamplitudes, but because they have shorterperiods, horizontal current velocities as-sociated with the seiche will exceed tidalcurrents. However, the most significanteffect of the long waves for any breachat Stump Hole is due to the geometry ofthe bay.

Figure 7. Plot of the qualified water level time series at Sites1, 2, & 3. Figure 8. Plot of the measured hydraulic head at Stump Hole

with wind stress components during deployment.

Figure 9. (A) Measured water levels during the frontal passage; (B) the measured and predicted hydraulic head during the frontalpassage.


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amplify and sustain them. The geometryof the bay causes the seiche at the back ofthe bay near Stump Hole to be nearly 180degrees out of phase with the incident longwave in the Gulf offshore of Sump Hole.

The combination of the amplificationand phase shifting of the long wavescan produce a significant hydraulic headacross Stump Hole that produces currentsseveral times faster, and that reverses sev-

eral times more quickly, than tidal forcingalone generates.

If a breach develops at stump hole, tidalcurrents alone will likely be sufficient to

maintain it. Under routine meteorologicalevents, the inlet will, for the short term,experience additional horizontal and ver-tical scour over that due to tidal forcingalone. A tropical storm or hurricane pass-ing near and to the east of St. Joseph Baywould be one of those conditions.

An inlet at Stump hole will have a signifi-cant effect on water quality inside St. JosephBay because water with high suspended

sediment concentrations from ApalachicolaBay discharge into the region immediatelyoffshore of Stump Hole. This water will becaptured on flood flows through any newinlet and injected into the bay.

ACKNOWLEDGEMENTS

The study reported in this paper wasconducted for the Florida Department ofTransportation under subcontract to Volk-ert & Associates, Inc, of Mobile, AL.Feedback from Dr. Scott Douglass with theUniversity of South Alabama was grate-fully accepted. The author also wishes torecognize the knowledgeable watermen inthe area who provided logistic support and

keen insights into the natural processes ofSt. Joseph Bay.

REFERENCES

Chen, Q. Jim, 2005. Hydrodynamic Modeling ofSt. Joseph Bay and Breach Stabili ty Analysisat Stump Hole, FL, Final report prepared forVolkert & Associates, Mobile, AL.

Coastal America, 1996. Coastal Restoration and

Protection, Coastal America TechnologyTransfer Report - January 1996, http://www.coastalamerica.gov.

Florida Department of Environmental Protection,Bureau of Survey and Mapping, 2000.Type of Tide, revised Dec. 14, 2000,http://data.labins.org/2003/SurveyData/W a t e r B o u n d a r y / M H W / d o c u m e n t s /

2typeoftide.pdfMcGehee, D., 2006. Results of a Study of WaterLevels in St. Joseph Bay, FL, Revised finalreport prepared for Volkert & Associates,Mobile, AL.

McGehee, D., 1991. Measured Response ofMoored Ship to Long Period Waves at LosAngeles and Long Beach Harbors,Bulletinof the Permanent International Association of

Navigation Congresses,Brussels, Belgium.

National Ocean Service, 2005. Center forOperational Oceanographic Prducts andServices (various web paes), http://co-os.nos.noa.gv


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Beach Nourishment Experience in the United States:

Status and Trends in the 20thCentury

By

Charles W. Finkl, Lindino Benedet, and Thomas J. CampbellCoastal Planning & Engineering, Inc.

2481 N.W. Boca Raton BoulevardBoca Raton, FL 33431

[email protected]

ABSTRACT

Beach erosion is a worldwide problem that isparticularly noticeable along developed shorelinesthat front open-ocean costs. Engineered responseto the coastal erosion problem in the United Statesfeatures the imposition of hard structures (suchas seawalls and groins), and soft structures suchas beaches and dunes. Beach nourishment hasbecome the shore protection measure of choicebecause it is a multipurpose approach that pro-vides economic and environmental advantages tothreatened coastal systems. Experience with theprocedure in the US over the last century identifies

trends towards improved methods of fill place-ment, better design strategies, and recognitionof increased potential of performance associatedwith larger fill densities. Maintenance volumes(expressed in terms of total volume per unit lengthper year) for Atlantic, Gulf and Pacific coast nour-

ishment programs decrease from north to southalong the Atlantic coast and from Atlantic coaststo Gulf coasts. Planning long-term nourishmentrequirements requires differentiation of volumet-ric maintenance needs from initial construction.Of the 1 x 109 m3 (one billion cubic meters) ofsediments removed from Americas beaches byengineering works and anthropogenic activity inthe past century, about 650 x 106m3 (six-hundredfifty million) have been returned to the beaches.There is thus a sediment deficit that needs to bemitigated over the long term.

ADDITIONAL KEYWORDS: Advance fill,beach erosion, shore protection, coastal engineer-ing, erosional hot spot, nourishment, sedimentbudget. Paper Submitted: 20 December 2005,

Revised and Accepted: 7 March 2006.

INTRODUCTION

Beach nourishment is an engineeringprocess that mechanically placeslarge volumes of sediment onshore

or in the nearshore zone to artificially com-pensate (vs. natural re-supply by coastalprocesses) for a net deficit of sediment

in a beach system. Artificial nourishmenthas advantage over structural methods ofshore protection because the procedurepreserves aesthetic and recreational val-ues of protected beaches by replicatingthe protective characteristics of naturalbeach and dune systems (Finkl and Walker2002; Campbell et al. 2003). Advantagesof nourished beaches compared to nativebeaches, or those beaches that fall behindscheduled renourishment, was poignantlydemonstrated in the 2004 hurricane seasonthat impacted the Florida coast with fourmajor storms (Benedet et al. 2005a; Clark

2005). Renourished beaches provided agreater degree of shore protection andgenerally fared better than non-nourishedbeaches (e.g. Walker and Finkl 2002).Curtailment of beach nourishment or ex-tension of the renourishment interval canhave serious consequences to the effec-tiveness of degraded beach-dune systemsfor shore protection (Finkl 1996).

This paper summarizes some of thelarger U.S. beach nourishment programsand trends by emphasizing volumes placed

and construction vol-ume per unit lengthof beach. Backgroundinformation related tonourishment designpractices is present-ed, and then followedby historical perspec-tives and simplifiedvolumetric and eco-nomic analyses ofbeach nourishmenttrends.

Principles andPractices of BeachNourishment

Although thereare several differ-ent approaches tobeach nourishment,procedures are gen-

erally distinguishedby methods of fillplacement, designstrategies, and filldensities (NRC 1995;Hanson et al. 2002;Dean 2002). Types ofnourishment accord-ing to the method offill emplacement in-cludes the following(Figure 1):

(A) Dune nourishment: Sediments areplaced in a dune system behind the beach.

(B) Nourishment of subaerial beach: Sedi-ments are placed onshore to build a widerand higher berm above mean water level,with some sand entering the water at apreliminary steep slope.

(C) Profile nourishment: Sediments aredistributed across the entire beach pro-

file, subaerial beach plus the submergedprofile.

(D) Bar or shoreface nourishment: Sedi-ments are placed offshore to form an arti-ficial feeder bar.

Figure 1. Types of nourishment defined on the basis of wherefill materials are placed: (A) Dune nourishment; (B) Subaerialbeach nourishment; (C) Profile or offshore; (D) Bar nourishment.


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Type B (nourishment of the subaerialbeach), the most common nourishmentpractice in the United States, occurs inresponse to economic factors and sedi-mentological properties of the fill mate-rial under coastal conditions that in turntranslate into performance of the placedmaterials. Positioning of the fill on thesubaerial beach initially produces a bermthat is wider than the targeted design

width because steeper construction slopeseventually equilibrate to milder naturalangles of repose under post-constructionwave action.

Renourished beaches are generally com-prised of three main components: a design(targeted) shoreline, an advanced fill (fillneeded to maintain the design shorelineduring the project lifetime), and a con-struction template.

The selection of additional beach widthto be achieved by artificial nourishment isusually determined by an iterative process

that evaluates costs and benefits as a func-tion of width and goals of the nourishmentprogram. Successful implementation ofnourishment programs requires consider-ation of technical and economic factorsthat, according to the NRC (1995) andCampbell and Benedet (2003), include:

(1) Establishment of baselines and objec-tives,

(2) Definition of costs and benefits,

(3) Search for and exploration of sand re-source areas (which includes evaluation oflocation and materials),

(4) Testing available theory and techniquesthat form the basis for design and predic-tion of project performance,

(5) Construction of initial nourishmentprojects,

(6) Monitoring initial projects,

(7) Assessing the validity of preliminaryassumptions,

(8) Identification of design strengths and

deficiencies,(9) Refinements of design,

(10) Development and presentation ofpublic awareness programs,

(11) Evaluation of decisions to renourishthat are based on monitoring data and de-sign expectations, and

(12) Improvement (modification) of initialdesign processes in subsequent renourish-ment efforts.

Design Practices Relatedto Sediment Compatibility

Two distinct approaches to beach nour-ishment design in the U.S. include stan-dardized design guidelines (USACE 1984;2002) and those that tend to be moregenerally adapted to local problems andconditions. Independent of these two ap-proaches there is an inherent need tocompare beach fill sands with native sands

when building new beaches. Attempts toevaluate compatibility between native andborrow (dredged) sands originated on thefederal side (e.g. Krumbein 1957, 1965;James 1975; USACE 1984) with simpli-fied one-dimensional parameters such asthe overfill parameter(R

A) and the renour-

ishment parameter(RJ).

Recent work conducted by Dean (1991;2000; 2002) questions the use of thesegrain-size factors (R

A and R

J) to estimate

beach fill volumetric requirements andperformance. Present design approaches tobeach nourishment instead favor the use ofequilibrium profile considerations (Deansmethod to determine compatibility of bor-row source and beach sediments) and com-binations of detailed coastal analysis (e.g.analytical methods or numerical modelingof cross-shore and longshore transportprocess, beach fill lateral diffusivity, back-ground erosion rates, etc.). Because over-fill and renourishment factors (R

Aand R

J)

are essentially based on textural properties(grain size and sorting) of native beachsediments and borrow areas, they do notincorporate the physics and complexitiesof each coastal system into the design

process. Their use in beach nourishmentdesign has thus declined. Uncritical appli-cation of standard design thus often al-lowed the coastal engineer to overestimateor underestimate nourishment needs.

Because the Dean equilibrium profilemethod (Dean 1991; 2002) is based on thepremise that a nourishment project dis-turbs the natural equilibrium of the coastalsystem, analysis of initial performanceof a fill project can thus be based on theprocess of returning the system to equi-librium. Particularly important to beach

nourishment design is the estimation ofdry beach width that results after initialprofile equilibration. Compared to nativebeaches, finer-grained sands produce mild-er slopes and generate non-intersectingprofiles. Coarser-grained sands producesteeper slopes and generate intersectingprofiles. Sand with similar grain size willreplicate the natural beach profile. Inter-secting profiles (coarser sands) translateto greater subaerial beach volumes per m3of sand placed on the beach, while non-

intersecting (finer sands) and submergedprofiles (similar sands) are characterizedby a distribution of the fill across the beachprofile and therefore less subaerial beacharea per m3of fill placed.

Two overarching processes are relevantto the design and performance of mostbeach nourishment projects: (1) cross-shore profile equilibration and (2) lat-eral spreading of fill material to adjacent

beaches (NRC 1995; Dean 2002). Otherprocesses that may account for lossesof sediment from the active beach sys-tem include: relative sea-level rise andbackground erosion, loss of sedimentsto expanding tidal inlets (Fitzgerald etal. 2003), overwash processes on bar-rier islands (Campbell and Benedet 2003),planform adjustments of headland baybeaches, and other small and large scalecoastal process.

Numerical models are often used to pre-dict cross-shore responses of nourished pro-

files to storms and alongshore transport offill sediments (e.g.Larson and Kraus 1989;Hanson and Kraus 1989; Roelvink and He-degaard 1993; Capobianco et al.2002). Toachieve satisfactory results, these modelsmust consider capabilities and limitationsin addition to being calibrated and verified.Analytical approaches may complementmodel results. Lateral spreading also maybe predicted by analytical methods thatrelate fill length and grain size to fill spread-ing rates (e.g.Dean, 2002) or by numericalshoreline modeling (e.g.Hanson and Kraus1989; Eysink et al. 2001).

Initial designs are usually refined onlong-term nourishment programs withpost-nourishment monitoring data to as-certain renourishment needs and calibratepredictions. Monitoring is important be-cause the performance of a sand-starvedbeach (pre-nourishment) can differ signifi-cantly to the performance of a sand-richbeach system. When long-term (e.g.morethan 10 years) monitoring data is avail-able for a nourishment program, model-ing requirements may be reduced by theanalysis of observed beach performance.Good monitoring data of nourishment per-

formance allow optimization of volumet-ric requirements to the most cost-effectivenumber during design phases by under-standing the morphodynamic responses ofthe coastal system in which the project isbeing built.

Background toCoastal Protection in the U.S.

Over the last three decades, beach nour-ishment has been the primary means ofshore protection and beach restoration in


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the United States, Europe, and Australia

(Finkl and Walker 2002; Walker and Finkl

2002). Beach nourishment was first at-

tempted in the U.S. almost a century ago.

Prior to World War II, the main approach

to beach erosion and control of storm dam-age was the use of fixed structures such

as groins, jetties, and seawalls. A classic

example of these early types of structures

is the Galveston, Texas seawall (Figure 2)

that was constructed in the early 1900s.By the 1920s and 1930s, fixed structures

were so common along resort sections of

the nations coastline that they impeded

recreational use of beaches. The late 1940s

and early 1950s, however, witnessed a

gradual migration away from structurestoward beach nourishment. This change in

approach to shore protection was driven

by desires to preserve aesthetic and rec-

reational values of protected beaches and

because nourishment gradually proved to

be more cost-effective and functional by

replicating the protective characteristics of

natural beach-dune systems. Beach nour-ishment combined with a limited number

of structures (e.g.,T-head groins), to main-

tain post-construction stability, are also in-creasingly deployed for coastal protection

in the U.S. (e.g., Silvester and Hsu, 1993;

NRC, 1995).

Major developments in shore protection

initiatives took place in the 1920s with the

emergence of funding to form an engineer-ing advisory board to study changes thatwere taking place along New Yorks coast-

line. At about the sametime, a Committee onShoreline Studies wasformed in the Divisionof Geology and Geog-raphy at the NationalResearch Council inWashington, D.C., re-sulting in the incorpo-ration of the American

Shore and Beach Pres-ervation Association(ASBPA). The ASB-PA, now merged withthe American CoastalCoalition, advocatesprotection of the U.S.coastline and promotesstate and national con-ferences as well aspublishing the Shore& Beachjournal.

In 1923, the firstlarge-scale beach

nourishment projectwas constructed onConey Island, NewYork, with local

funds. The project used about 1.3 x 106m3of sand along 2.8 km of shoreline, pro-viding 449 m3 m-1 (449 cubic meters permeter) construction density (in this con-text construction density refers to unitvolume per unit length of shoreline, that iscubic meters per meter) of placed fill. Dur-ing the 1930s and 1940s, with intense hur-ricanes affecting Gulf and Atlantic coasts,coastal protection was advanced by local

initiatives while federal involvement wasmostly limited to cooperative analyses andplanning studies. From the late 1940s tothe 1960s, many state coastal protectionprograms were implemented and somelarge-scale beach nourishment projectswere constructed (e.g., Grand Isle, Loui-siana; Palm Beach, Florida; RockawayBeach, New York).

BEACH NOURISHMENTPROGRAMS ALONG

THE ATLANTIC COAST

Although all Atlantic coastal states ad-

opted beach nourishment as a means ofshore protection, the most significant pro-grams (by number of projects and total

volume of sand placed on the shore) wereinitiated in New York, New Jersey, NorthCarolina and Florida. Not coincidentally,these states have the most intensely de-veloped (urbanized) shores that requireprotection from storm surge flooding anderosion.

THE NORTH ATLANTIC COAST(NEW YORK, NEW JERSEY,

DELAWARE AND MARYLAND)

Due to coastal proximity of the NewYork City conurbation, the states of NewYork and New Jersey have spatially ex-tensive and temporarily extended beachnourishment histories that include the firstlarge project built in the nation (ConeyIsland). Most large New York beach re-nourishments are federal projects built andmaintained by the U.S. Army Corps ofEngineers (USACE) (e.g. USACE 1964;1993). Total volumes dredged onto NewYork beaches since the 1930s is aroundto 80 x 106 m3 of sediments from off-

shore and channel maintenance sources(volumetric range modified from DUKEPSDS 2003, to eliminate repeated oc-currences). Continuing nourishment pro-grams in New York include RockawayBeach, Gilgo Beach area, Coney Islandarea, Jones Beach, etc.

Coney Island is the earliest beach nour-ishment project constructed in New York(and in the U.S.). The history of the ConeyIsland nourishment program is summa-rized in Table 1. The 1995 Coney Islandproject was constructed 30 years after thelast renourishment and therefore required

densities equivalent to initial constructionsto restore the beach to a 30 m design bermwidth. The project provided 15 m of ad-vanced fill for a 10-year renourishmentcycle. Sediments were placed along 2.8 kmof beach and provided a sand fillet down-drift of terminal groins (USACE 2003).

Total volumes dredged onto New Jerseybeaches since the mid 1930s are estimatedto be around to 60 x 106 m3 of sandysediments from offshore and channelmaintenance sources. Major nourishmentprograms have been maintained in the

last decades in Ocean City (since 1950),Atlantic City (since 1936), and Cape May(since 1962).

Figure 2. A section of the Galveston, TX seawall, currently 16km long and 5 m high, showing the concave outward shapeand rubble mound toe structure. The seawall was constructedafter the 8 September 1900 hurricane, when a 3 -m high stormsurge flooded into the states then largest city with 36,000residents. This hurricane, which killed 6,000-8,000 people,is considered by many authorities to be the worse naturaldisaster in U.S. history.

Table 1. History of the Coney Island nourishment program.


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8-16

From the late 1980s to the present,the USACE conducted its largest beachnourishment project ever along 34 km ofthe New Jersey coast (Sandy Hook to Bar-negat Inlet). The project was divided intotwo sections: Section I is 19 km long fromSea Bright to Ocean Township and SectionII is 14 km long extending from AsburyPark to Manasquan Inlet. Feasibility anddesign level studies for the project were

conducted during the late 1980s to early2000 by a joint venture between CoastalPlanning & Engineering Inc., URS, andthe USACE (e.g., Beumel and Camp-bell 1988; Beumel and Bocamanzo 1989).Constructed project features included a de-sign berm of 30 m plus 12 m of advancedfill for Section II and a design berm of 30m plus 7 m advanced fill for Section 1. Thebeach was designed on a six-year cycle ofrenourishment for 50 years from initialconstruction. The project was constructedin five different phases and used about 15 x106m3of sediments in the initial construc-tion cycle (USACE-Web 2003) with totalconstruction densities (initial constructionplus advanced fill) ranging from 330 m3m-1to 730 m3m-1for the Sea Bright area. Filldensities from Shark Inlet to ManasquanInlet averaged 570 m3 m-1. Maintenancerenourishment of Phase I - Sea Bright toMonmouth Beach took place from May toDecember 2002 and used about 1.5 x 106m3 of sediments along 8.8 km of beach(about 174,000 m3m-1).

Relatively smaller, maintenance dredg-ing and storm-erosion control projectsin Delaware (i.e., Indian River Beach,

Dewey Beach, and Fenwick Island) col-lectively account for about 5 x 106 m3of placed sediments. Marylands majornourishment program at Ocean City usedabout 7.5 x 106 m3 of sediments since itwas implemented in 1988. The Ocean Cityproject was initially constructed between1988 and 1991, in two separate phases andextended for about 11 km (Grosskopf andStauble 1993). Phase I was constructed in1988 by the state and used about 1.7 x 10 6m3of sediments (153 m3m-1) while PhaseII was constructed from 1990 to 1991 andused about 2.7 x 106m3 (237 m3m-1) (Mc-

Gean 2003). Since completion of the 1991project, the beach has been renourishedfour times in response to severe storms(1992, 1994, 1998 and 2002).

A nourishment program at Virginia Beachhas been maintained since 1952. The stateof Virginia generally nourishes the beachwith smaller volumes (less than 250,000m3) over short periods of time (1-2 yrs) us-ing dredging maintenance sediments fromthe updrift side of Rudee Inlet and offshore

sources combined. Up to 11 x 106 m3 ofsediments were placed on Virginia Beachsince the beginning of nourishment in1952. Recently the city of Virginia Beach

jointly with the USACE Norfolk Districtprepared a 50-year storm protection planfor the city. The project consists of alarge beach-wide initial construction andperiodic maintenance using about 750,000m3on a 3 to 4 year renourishment interval.

The initial construction was completed in2002 when about 3 x 106m3of sedimentswere placed along approximately 9.6 kmof beach (construction density of 316 m3m-1). Maintenance volumes anticipated bythe USACE are approximately 77 m3m-1every 3-4 years (about 19 m3 m-1 yr-1).(Maintenance requirements for beach fillare best expressed in terms of total volumeper year, m3yr-1, or volume per unit lengthof beach per year, m3 m-1yr-1.)

The South Atlantic Coast (NorthCarolina, South Carolina, Georgia,Florida)

North Carolina has about 20 nourishedlocations where about 10 received morethan 1 x 106 m3 of sediments. Total vol-ume of sediments placed on North Caro-lina beaches since the 1950s range upto 40 x 106 m3. The two largest nour-ishment programs (in terms of volumeplaced) are Carolina Beach and Wrights-ville beach (USACE 1983; 1984; Jarrett2003). Wrightsville Beach received about8.5 x 106m3since its initial nourishmentin 1965. A major part of this volume isbeneficial material (about 50%) from themaintenance dredging or bypassing from

Masonboro Inlet. The initial constructionat Wrightsville Beach used 1.7 x 106 m3of sediments along 4.2 km of beach toachieve a construction density of about410 m3 m-1. Since that time, the NorthCarolina beach nourishment program hasbeen maintained with about 7 x 106m3 ofsediments (about 200 m3yr-1).

There are about 15 nourished areasin South Carolina that together receivedabout 20 x 106m3of sediments since thelate 1960s. Relatively large nourishmentprojects along the shore include Myrtle

Beach, Folly Beach, Hunting Island, andHilton Head Island. The last project (Hil-ton Head Island) used about 5.5 x 106m3of sediments since the 1970s (Olsen et al.1993; 1987; Kana 1993). The two mostrecent nourishments were constructed in1990 (1.8 x 106 m3 along 10.5 km ofbeach) and 1997 (1.7 x 106m3along 11.5km) with average densities of 167 m3m-1and 165 m3m-1, respectively. Recent main-tenance needs for the Hilton Head Islandproject were estimated to be on the order

of 125,000 m3yr-1by Bodge et al.(1993)based on a sediment budget developed forthe area.

There are two project areas in Georgia.Both Tybee Island and Sea Island togetherreceived up to 5.5 x 106m3of sediments.Tybee Island, located downdrift of the Sa-vannah River, received about 4.0 x 106m3of sediments during four different nourish-ments since 1975. The beach was initially

nourished in 1975 with about 1.7 x 106m3

of sediments along 4.1 km of beach (418m3 m-1). From 1975 to 2000, the beachreceived about 3.8 x 106m3of sediments(153,000 m3yr-1), giving an overall islanddensity of about 35 m3m-1. Major renour-ishments occurring in 1990 and 1994 usedapproximately 1.5 x 106 m3 each. Olsenand Bodge (1993) reports that a large por-tion of the 1994 renourishment volumewas, however, lost during fill placement(dewatering) due to low quality of borrowarea materials (high percentage of fines).The beach was renourished in 2000 by the

USACE.

Florida, the most southern state, hassuccessful beach nourishment programson both Atlantic and Gulf coasts. TheAtlantic coast has about 50 nourishedareas that together received up to 65 x106m3of sediments since the mid 1940s.Miami Beach, built from 1978 to 1982,was the largest single construction eventin the history of beach nourishment onthe U.S. East Coast with about 9.2 x 106m3of sediments dredged from several dif-ferent borrow areas located in inter-reefal

sediment troughs along 17 km of shoreline(construction density of 543 m3m-1). TheMiami Beach nourishment project dem-onstrates excellent performance relativeto other U.S. projects (NRC 1995; Wiegel1992). The success of the Miami Beachproject may be attributed to the long extentof the nourished area (17 km) that reducesfill spreading rates (e.g., Dean 2002), arelatively low wave energy, relatively highconstruction density, and the fact that theproject ends at a very long downdrift jettywhere the sand accumulates.

Other major nourishment programs on

the Florida east coast include JacksonvilleBeach, Amelia Island, Jupiter Island, Del-ray Beach, Boca Raton (north and south)beaches, Pompano Beach/Lauderdale-by-the-Sea, etc.Delray Beach is an exampleof a successful and well monitored beachnourishment program. Delray has beenmaintained since 1973 with five peri-odic beach nourishments. Pertinent datafor Delray Beach nourishment projects issummarized in Table 3.


12/40


Since inception, about 4.5 x 106m3ofsediments were placed on Delray Beach.The project employed an initial construc-

tion density of 293 m

3

m

-1

(Table 3), butfrom 1978 to 2001 the program was main-tained with an average volume of about 10x 105m3yr-1or about 24 m3m yr-1(usingthe maximum project length of 4.2 km).Delray is an example of a successful beachnourishment program (Fernandez 1999;Dean 2002; Benedet et al. 2005b; CPE2002) and currently contains a healthyrestored beach-dune system. The intervalbetween renourishments has been gradu-ally increasing from 5 (initial renourish-ment) to 10 years (last renourishment).

GULF COAST

NOURISHMENT PROGRAMS

The Florida Gulf coast (including thePanhandle) has about 30 nourishment pro-grams that received up to 38 x 106m3ofsediments since the 1960s. Many FloridaGulf coast programs employ a combi-nation of beneficial sands and offshoresand sources to replenish beaches (e.g.,Panama City, Lido Key, Treasure Island)but some, however, rely exclusively onbeneficial sands (e.g., Perdido Key, FortMyers Beach, Gasparilla Island, Keeway-din Island). The largest project is PanamaCity Beach. Panama City had small nour-ishments in the 1970s and 1980s that usedbeneficial materials from St. Andrews In-let. In 1999, a major nourishment projectwas constructed along 28 km of beach.The project was the largest single con-struction event on the U.S. Gulf coast andused about 6.8 x 106 m3of sediments (244m3m -1). Total volumes placed on PanamaCity Beach, combining small maintenanceprojects with the 1999 nourishment are onthe order of 7.8 x 106m3.

Other large nourishment programs ofthe Florida Gulf coast (over 2 x 106 m3)include Perdido Key, Anna Maria Key,

Longboat Key, Sand Key, and Captiva Is-land. Anna Maria Key and Longboat Keyare two adjacent barrier islands; LongboatKey was nourished in its entirety in 1993with about 2.4 x 106m3of sediments along15 km of beach (about 170 m3m-1) usingsediments slightly finer than native sands(Jenkins and Keehn, 2001). The middle ofthe island was renourished in 1997 withabout 680,000 m3 along 5 km of beach(132 m3m-1) using coarser sand.

The first major nourishment project con-structed in Alabama took place in 2001 atGulf Shores. The project used about 1.6 x

106 m3 of sediment along 5 km of beach(330 m3 m-1). In addition to this initialproject, local and state agencies joinedefforts to restore 18 km of shoreline alongOrange Beach, Perdido Key, and GulfShores in 2004. Volumes to be placedwere not released to public at the time ofthis writing.

Major nourishments in Mississippi in-clude a countywide program in HarrisonCounty and a program that uses beneficialsediments (navigation) to beaches adjacentto the Mississippi River channel. The larg-

est program on the Mississippi coast andperhaps one of the largest (by total vol-ume) on the U.S. Gulf coast, is HarrisonCounty. Since 1952, about 8.1 x 106m3ofsediments have been placed along about40 km of coastline. The largest construc-tion event in Harrison County occurred afew decades ago, from 1951 to 1952. Theproject used about 5.3 x 106m3along 40km of beach providing a construction den-sity of 130 m3m-1.

Several projects have been constructed(since the 1990s) along Louisianas bar-rier islands and Chenier plains under theCoastal Wetlands Planning, Protection,and Restoration Act (CWPPRA) of 28November 1990 (www.lacoast.gov) underthe supervision of the Louisiana Depart-ment of Natural Resources. Some recentprojects built along Louisiana barrier is-lands are shown in Table 4. Because of

the high rate of land loss, and the needto restore back and front sides of barrierislands, construction densities (m3 m-1)employed in the Louisiana Barrier islandsare generally greater than those employedin other Gulf coast projects.

Louisiana contains a long shorelinecomposed of several deltaic barrier is-lands, bays (Arcadian bays), a long Che-nier plain, and several major navigationchannels. Over the last several decades,the greatest land losses in the country haveoccurred in the wetlands of the Missis-sippi delta and along barrier island fronts.

Over the last few decades, prior to modernnourishment efforts, total volumes placedon Louisiana barrier islands and beaches(including recent CWPPRA projects andthe Grand Isle program) are in the range of12 x 106m3of sediments. Grand Isle is theonly nourishment program maintained inthe state since the mid-1950s, with about4.1 x 106m3of sand placed since that time(USACE 1980).

The latest major project (built in 1983-1984), the largest in terms of volume andlateral extent, used about 2.15 x 106 m3

of sediments along 11 km of shoreline(Combe and Soileau 1984) giving con-struction densities around 195 m3 m-1.Annual densities used to maintain theGrand Isle program since the 1950s rangearound 8 m3m-1yr-1. Several breakwaters,groins and T-head groins have been builtin conjunction with beach nourishment onGrand Isle. Recent initiatives under theLouisiana Coastal Area (LCA) programprovide support for the implementationof large-scale barrier island nourishmentprograms along this coast. Hurricanes Ritaand Katrina in 2005 reconfigured Louisi-anas barrier island shorelines and plansto restore these eroded shores are beingdeveloped. Restoration interventions, in-cluding beach nourishment, have not beenimplemented because volume losses haveyet to be calculated.

PACIFIC COASTNOURISHMENT PROGRAMS

There are many differences between theU.S. Atlantic and Pacific coast beaches.Atlantic beaches are mainly open-coast

Based on Fernandez (1999), Dean (2002), Benedet et al. (2003), CPE (2002, 2003), proprietary data, and various

other sources.

Table 3. Delray Beach, (Palm Beach County) Florida, renourishment project history.

Based on Campbell, Benedet, and Finkl, 2005.

Table 4. Some recent projects constructed in Louisiana.


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densities usually characterize projects thatare designed for a short lifetime (e.g., fouryears) or that require little initial volume tomeet design conditions, while high densityconstriction projects are usually designedfor longer lifetimes (8-20 years) or requirelarge initial volumes to meet the designconditions (e.g., a 30 m design beach re-stored from a 5 m existing beach). On thebasis of this analysis (Table 5) and previ-ous experience, the authors suggest that,generally, initial construction volumes can

be divided into three categories: (1) low ( 400 m3m-1).

Table 5 also provides a basis for inter-pretation and inter-comparison of beachnourishment projects. Before factors areattributed to engineering performance ofa specific nourishment project, due con-sideration should be given to the construc-tion density (volume of sediment per unitlength) placed on the beach. Experience in

the U.S. indicates that if very low initialconstruction densities (e.g., < 100 m3m-1)are placed along an open-ocean coast, theproject will be unlikely to succeed regard-less of how comprehensive pre-projectfield investigations and numerical model-ing efforts were.

Regional trends deduced from the con-struction densities summarized in Table 5show some important relationships. Con-struction volumes seem to be directly

related to the wave energy and magnitudeof sediment transport along a given coast-al segment. Along the northeast Atlanticcoast (from New York to North Caro-lina), construction densities are generallyin the high range (>400 m3m-1), whereasalong the southeast Atlantic coast (SouthCarolina to Florida) construction densitiesgenerally occur in the low to intermedi-ate range. Gulf coast beach nourishmentprojects generally fall in the intermediatecategory with the exception of Louisiana

where high construction densities resultfrom double-sided nourishment (frontand back sides of barrier islands) designedfor a 20-year lifetime. Extremely highconstruction densities (in the range of1,000 m3m-1) along the Pacific coast oc-cur in California as a byproduct of coastalconstruction (opportunity nourishments).Due to these very high initial constructiondensities, the maintenance nourishment

demand in most California pre-nourishedcoastal segments has been relatively lowin recent years. This situation is expectedto change in future as the large volumesplaced on the 1940s to the 1960s are trans-ported out of the littoral system.

MAINTENANCE NOURISHMENT(RENOURISHMENTS)

Proper maintenance of a nourishmentproject is important for the long-termsuccess of a nourishment programs alongopen-ocean coasts. Because the designtemplate is restored by initial construc-

tion, subsequent renourishment usuallyprovides maintenance fill (advanced fill)to the project area in order to maintain theexisting design template for the renourish-ment cycle. Erosional hot spots exhibitlocally higher sediment loss rates than ad-

jacent areas within a project. When devel-opment of a hot spot occurs, initial beachdesign conditions are usually exceeded.Therefore, subsequent renourishment sup-plies additional sediment in the erosionalhot spot to (1) restore the beach to designconditions and (2) counteract higher ratesof erosion that occur in the hot spot.

Because mainly advanced fill is placedon renourishment beaches, smaller vol-umes per unit beach length (density) arerequired. In the example of the Sea Brightto Monmouth Beach, New Jersey project,initial construction (restoration) volumeper unit length of beach was about 750m3 m-1. The first renourishment recentlyconstructed in the same area used a densityof about 175 m3 m-1. These maintenancevolume requirements are shown for a fewselected areas in Table 6.

Maintenance volumes for these projects

(Table 6) range from 15 to 25 m3

m-1

yr-1

,with general decreasing trends from northto south and from Atlantic to Gulf coasts.These trends seem to be a function ofdecreasing wave energies resulting fromthe wave shadow of the Bahamian Archi-pelago and semi-enclosed Gulf of Mexicowith limited fetches. These volumes returnconstruction densities (considering totalproject length and design lifetime) thatare significantly lower than those shownin Table 5. Although initial construction

Bernas, 2003; Ciorra, 2003; CPE, 2000; Jarrett, 1988, 2003; USACE, 1973; Weaver, 2003; and based on other

references cited in the text for each state or project.

Table 5. Initial construction densities for selected U.S. beach (re)nourishmentprojects.


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Shore & Beach Vol. 74, No. 2, Spring 2006, pp.158-16

densities in the range 300-400 m3m-1arecommon (Table 5), maintenance densitiesusually range from 50-200 m3m-1. Finally,assuming a five-year design lifetime forthe projects (Table 6), maintenance fillrequirements would range from 70-120m3m-1.

Thus, when planning long-term nour-ishment, it is essential to differentiatebetween volumetric maintenance needsand initial construction. Calculation ofvolumetric requirements should be basedon project objectives and goals (desiredbeach width), design lifetime, pre-projectbeach conditions (existing volume/width),and local coastal processes (coastal energyregime, magnitude of background erosion,sediment transport out of the littoral cell,geometric dimensions of the beach, clo-sure depth, berm height, etc.).

This review indicates that the total vol-umes artificially placed on the beach (vari-ous types of nourishment) since the early

1930s are in the range of a 650 x 10 6m3of sediments (Table 7). Douglass et al.(2003) estimated that about 1 x 109m3ofsediments were removed from Americasbeaches by engineering works (e.g., riverdamming, sediment disposal offshore, sea-walls inhibiting cliff erosion, etc.) to date.

There is thus a deficit of about 350 x 106m3in the national sediment budget thatneeds to be mitigated over the long term. Itis cautioned that the Douglass et al.(2003)sediment volumes and those summarizedhere are conservative estimates that aresubject to unknown errors.

CONCLUSIONS

Beach nourishment is the most com-

monly practiced method of shore protec-tion and restoration in the United States.Over the last few decades, beach nour-ishment design has evolved from simpledredge and placement projects of stan-dardized designs to holistic and site-spe-cific designs that encompass most physicalcomplexities of coastal systems. There arepronounced difference in the principles andpractices of beach nourishment along U.S.coasts. Although nourishment projects onthe Atlantic, Gulf, and Pacific coasts weretriggered by the need to provide shoreprotection against the impacts of storms

and hurricanes (coastal flooding, shoreerosion), East and Gulf coast nourishmentprojects largely depended on marine sandsearches to locate suitable offshore bor-rows, whereas Pacific coast projects fea-tured the use of beneficial sediments fromnumerous coastal developments.

Densities of beach fills vary significant-ly with coastal regime. Initial constructionvolume per unit length of beach for shoreprotection works generally ranges from150-600 m3m-1. Based on the projects dis-cussed here, we propose a classification ofsediment volume per unit length of beachinto three categories: (1) High, > 400 m3m-1, (2) Intermediate, 200-400 m3m-1, and(3) Low, < 200 m3m-1.

High volumes per unit length of beachgenerally characterize projects where largeinitial restoration needs and/or long designlifetimes are required. Most beach nour-ishments in the U.S. involve some initialrestoration requirement and a 5-8 year de-sign lifetime, thus falling into the interme-diate range. Low volume per unit lengthof beach is associated with projects thatprovide only advanced fill for the designperiod. This classification of beach nour-ishment projects as a function of volumeper unit length of shore should facilitatecomparison of project magnitude.

Aside from design lifetime and proj-ect objectives, many other local factors(e.g., the presence or absence of coastalstructures, wave energy, closure depth,rate of littoral drift, relative sea-level rise,background erosion rates, sediment com-patibility, etc.) influence the volume perunit length of beach sediment that shouldbe placed.

Of the one billion cubic meters of sedi-ments removed from Americas beachesby engineering works and human activity,it is estimated that a little more than 650

million m3of sediments were returned tothe beaches. There is thus a sediment defi-cit on the order of about 350 million m3ofsediments that will need to be mitigatedover the long term.

Table 6. Deployed and predicted maintenance volumes for selected Atlantic and Gulfcoast renourishment projects.

REFERENCES

Benedet, L., Campbell, T., Finkl, C.W., Stive,M.J.F., and Spadoni, R., 2005a. Impactsof Hurricanes Frances and Jeanne on twonourished beaches along the southeast Floridacoast, Shore & Beach, 73(2-3), 43-48.

Benedet, L., Klein, A.H.F., and Hsu, J.R.C.,2005b. Practical insights and applicabilityof empirical bay shape equations, Smith,McKee, J., (ed.), Proceedings of the

International Conference on CoastalEngineering, Singapore: World Scientific,2, 2181-2193.

Bernas, J., 2003. Personal e-mail communication,City of Virginia Beach: Public Works-BeachManagement.

BeumeL, N.H. and Bocamozo, L.B., 1989.Rebuilding the New Jersey Shoreline,Proceedings of Coastal Zone 89, 2060-2075.

Beumel, N.H. and Campbell, T.J, 1988. Restoringthe New Jersey Shoreline, Proceedings ofthe First Beach Preservation TechnologyConference, 241-248.

Bodge, K. R., Olsen, E.J., and Creed C.G., 1993.

Performance of beach nourishment at HiltonHead Island, South Carolina, Proceedings

Eighth Symposium on Coastal and OceanManagement (Coastal Zone 93).

Campbell, T. and Benedet, L, 2003. BestManagement Practices for CoastalRestoration in Louisiana, Science Based

Restoration for the Louisiana Gulf Coast,Appendix O, Louisiana Coastal Area Study,19 pp.

Campbell, T., Benedet, L. and Finkl, C., 2005.Regional Strategies for Coastal Restorationalong Louisiana Barrier Islands,Journal ofCoastal Research, SI 44, 245-268.

Campbell T., Benedet, L., Mann, D., Resio, D.,Hester, M.W., and Materne, M., 2003.Coastal Restoration Tools for LouisianasGulf Shoreline, Science Based Restoration

for the Louisiana Gulf Coast, Appendix O,

Louisiana Coastal Area Study, 30 pp.Capobianco, M., Hanson, H., Larson, M., Steetzel,

H., Stive, M.J.F., Chatelus, Y., Aarnikhof,S., and Karambas, T., 2002. Nourishmentdesign and evaluation: applicability of modelconcepts, Coastal Engineering, 47(2), 113-137.

Clark, R.R., 2005. Impact of the 2004 NorthAtlantic hurricane season in the coast ofFlorida, Shore & Beach, 73(2-3), 2-9.

Clayton, 1991. Beach replenishment activities onU.S. continental Pacific coast,Journal ofCoastal Research, 7(2), 1195-1210.

Ciorra, A., 2003. Personal e-mail communication,USACE Philadelphia District.


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Coastal Planning & Engineering (CPE), 2000.Panama City Beach, Florida, Beach ErosionControl and Storm Damage ReductionProject: Preliminary Engineering Report.Boca Raton, Florida: Unpublished report.

CPE, 2002. City of Delray Beach, Fourth PeriodicBeach Renourishment Project: 2002 Post-Construction Monitoring Study. Boca Raton,Florida: Coastal Planning & Engineering,Unpublished report.

California Department of Boating and Waterwaysand State Coastal Conservancy, 2002.California Beach Restoration Study.Sacramento, California.

Dean, R.G., 1991. Equilibrium beach profiles:Characteristics and applications,Journal ofCoastal Research, 7(1), 53-84.

Dean, R.G., 2000. Beach Nourishment Design:Consideration of Sediment Characteristics.Gainesville, Florida: UFL/COEL-2000/002,Department of Civil and Coastal Engineering,University of Florida.

Dean, R. G., 2002. Beach Nourishment: Theoryand Practice, River Edge, New Jersey:World Scientific, 397 pp.

Douglass, S.L., Bobe, A., and Chen, Q.J.,2003. The amount of sand removed fromAmericas beaches by engineering works,

Coastal Sediments 03, Clearwater, Florida,CD-ROM.

Eysink, W.D., Walstra, D.J.R., and Stive, M.J.F.,2001. Comparison of Existing Long-Term

Morphological Models, Delft, Netherlands:WL Delft Hydraulics, Report Z3005[Dutch].

Fernandez, G.J.S., 1999. Erosion Hot Spots atDelray Beach Florida: Mechanisms andprobable Causes , Gainesville, Florida:University of Florida, Masters thesis, 120pp.

Finkl, C.W., 1996. What might happen toAmericas shorelines if artificial beachreplenishment is curtailed: A prognosis forsoutheastern Florida and other sandy regionsalong regressive coasts, Journal of Coastal

Research, 12(1), ii-ix.

Finkl, C.W. and Walker, H.J., 2002. Beachnourishment, Chen, J., Hotta, K., Eisma,D., and Walker, J. (eds.), Engineered Coasts,Dordrecht, The Netherlands: Kluwer, 1-22.

Fitzgerald, D. M., Argow, B. A., and Buynevich,I. V., 2003. Rising sea lever and its effecton backbarrier marshes and tidal flats,tidal Inlets and barrier shorelines, CoastalSediments03, CD-ROM.

Flick, R. E., 1993. The myth and reality ofsouthern California beaches, Shore & Beach61(3), 3-13.

Grosskopf, W.G. and Stauble, D.K., 1993. Atlanticcoast of Maryland (Ocean City) shorelineprotection project, Shore & Beach, 61(1),3-7.

Hanson, H. and Kraus, N.C., 1989. GENESIS-Generalized Model for Simulating Shoreline

Change, Vol. 1: Reference Manual and UsersGuide, Technical Report, CERC-89-19.Vicksburg, Mississippi: US Army EngineerWaterways Experiment Station, CoastalEngineering Research Center, 247 pp.

Hanson, H., Bramptom, A., Capobianco, M., Dette,H.H., Hamm, L., Lastrup, C., Lechuga, A.,and Spanhoff, R., 2002. Beach nourishment

projects, practices, and objectives - aEuropean overview, Coastal Engineering,47(2), 81-113.

Hearon, G., Lockwood, B., and Sherman, D.,2001. California Public Beach NourishmentProgram, California Beach RestorationStudy, California Department of Boating

and Waterways and California CoastalConservancy, 5-1 to 5-34, (http://dbw.ca.gov/beachreport.asp).

Herron, W. J, 1980. Artificial beaches in southernCalifornia, Shore & Beach 48(1), 3-12.

Hsu, J.R.C., Klein, A.H.F., and Benedet, L., 2005.Geomorphic Approach for Mitigating BeachErosion Downdrift of Littoral Barriers,Smith, J. McKee (ed.), Proceedings ofthe International Conference on Coastal

Engineering, Singapore: World Scientific,2, 2022-2034.

James, W.R., 1975. Techniques in evaluatingsuitability of borrow material for beachnourishment. Vicksburg, Mississippi, U.S.Army Engineer Waterways ExperimentsStation, Coastal Engineering ResearchCenter, TM-60.

Jarrett, T., 1988. Performance of the WrightsvilleBeach, North Carolina shore protectionproject,Proceedings of the First BeachPreservation Technology Conference, 59-65.

Jarrett, 2003. Personal e-mail communication,Coastal Planning & Engineering Inc., NorthCarolina.

Jenkins, M. and Keehn, S., 2001. Effects ofbeach nourishment on equilibrium profileand closure depth, Proceedings of Coastal

Dynamics(Lund, Sweden), 1, 888897.Kana, T.W., 1993. South Carolina beach

nourishment projects success and failures,Proceedings of the Hilton Head Island

International Coastal Symposium, 255-260.Krumbein, W.C. 1957.A Method for Specification

of Sand for Beach Fills, Washington, DC:U.S. Army Corps of Engineers, Beach

Erosion Board, Technical Memorandum102.

Krumbein, W.C. and James, W.R., 1965. Alognormal size distribution model forestimating stability of beach fill material,Fort Belvor, Virginia: U.S. Army CoastalEngineering Research Center, TechnicalMemorandum 16, 17 pp.

Larson, M. and Kraus, N.C., 1989. SBEACH:Numerical Model for Simulating Storm-induced Beach Change, Report 1: EmpiricalFoundation and Model Development.Vicksburg, Mississippi: US Army EngineerWaterways Experiment Station, CoastalEngineering Research Center, TechnicalReport CERC-89-9.

McGean, T. 2003. Personal e-mail communication,Ocean City, Maryland: Engineering

Department.

National Research Council, 1995. BeachNourishment and Protection. WashingtonDC: U.S. National Academy of Sciences,Marine Board, Commission on Engineeringand Technical Systems, U.S, 290 pp.

Olsen, E.J. and Bodge, K., 1993. Performanceof Beach Nourishment at Hilton HeadIsland, South Carolina, Proceedings of the

Hilton Head Island International CoastalSymposium, 145-150.

Roelvink J.A. and Broker Hedegaard, I., 1993.Cross-shore profile models, H.J. de Vriend(ed.), Coastal Morphodynamics: Processesand Modelling, Coastal Engineering, 21,163-191.

Silvester, R. and Hsu, J.R.C., 1993. CoastalStabilization, Singapore: World Scientific,578 pp.

U. S. Army Corps of Engineers (USACE), 1964.Atlantic Coast of New York City from EastRockaway Inlet to Rockaway Inlet andJamaica Bay, New York, Cooperative BeachErosion Control and Interim hurricane study.New York District, USACE, 47 pp.

USACE, 1973. Atlantic Coast of New York Cityfrom Rockaway Inlet to Norton Point, NewYork (Coney Island Area), New York District,USACE: Cooperative Beach Erosion Control

and Interim Hurricane Study, 52 pp.USACE, 1980. Grand Isle and Vicinity, Louisiana.

Phase I General Design Memorandum, NewOrleans District: Unpublished report preparedby the U.S. Corps of Engineers, 79 pp.

USACE, 1983. Feasibility Report andEnvironmental Assessment on Shore andHurricane Wave Protection, WrightsvilleBeach, North Carolina, 45 pp.

USACE, 1984.Shore Protection Manual, Vicksburg,Mississippi: Waterways Experiment Station,Coastal Engineering and Research Center,1, 639 pp.

USACE, 1993. Atlantic Coast of New York Cityfrom East Rockaway Inlet to Rockaway Inletand Jamaica Bay, New York, PhiladelphiaDistrict: Final Reevaluation Report (Section934 of WRDA 1986), 89 pp.

USACE, 2002. Coastal Engineering Manual.Washington, D.C.: Engineer Manual 1110-2-1100, U.S. Army Corps of Engineers (6volumes).

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Wiegel, R.L., 1992. Dade County, Florida, beachnourishment and hurricane surge protectionproject, Shore & Beach, 60(4), 2-28.

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USA Pacific Coast, Shore & Beach, 62(1),11-36.

REFERENCES CONTINUED


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COASTAL OBSERVATIONS

Heron Island, Great Barrier Reef, Australia

By

Hubert Chanson, ReaderDepartment of Civil Engineering

University of Queensland

Brisbane QLD 4072, [email protected]

Heron Island is a coral cay islandlocated 72 km northeast off Glad-stone, Queensland, on the Tropic of

Capricorn (Figure 1). It is on the southernpart of the World Heritage-listed Great Bar-rier Reef extending along the North-Eastcoast of Australia. The island area is only42 acres with a circumference of 1.8 km.

The island was named by HMS Flysnaturalist, Joseph B. Jukes, who mistookthe egrets for herons. The birds are part ofthe rich wildlife that inhabits the island, in-

cluding flocks of mut-ton birds and terns.The island is also abreeding ground forgreen and loggerheadturtles. It remaineduntouched until 1932,when Captain Chris-tian Poulson wasgranted a lease over

the island to developa tourist resort. Since1932 it has been a re-sort, and today HeronIsland is a typicalBarrier Reef holiday

resort. The University of Queenslandmaintains a research station on the south-ern side of the island. Figure 1 shows amap of the island and lagoon. Figures 2-5present photographs of Heron Island takenDec. 24-27, 2001. Figure 6 (Dec. 25,2001) shows a female green turtle return-ing to the water after lying her eggs on the

beach the previous night.

The wreck of HMCS Protector, shownin Figure 5, has been used since 1946as a breakwater to protect Heron Island.

Figure 1. Schematic map of Heron Island.

Figure 2. South beach on Dec. 24, 2001.

Figure 3. Northwest beach, north of harbor at low tide. The wooden gantry (left) wasused to transfer people and supplies prior to the construction of the harbour.

Figure 4. Shark Bay, eastern side of HeronIsland on Dec. 26, 2001, at low tide.

Figure 5. Wreck of HMCS Protectoron Dec. 27, 2001, at low tide. Note theconcrete block wall (foreground) used tomaintain tide range in the reef despite theharbor excavations.


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Figure 6. Green turtle at sunrise Dec. 25, 2001, and high tideon the beach south of harbor.

This wreck has aninteresting history.HMCS Protector wascompleted in 1884 asa colonial warship.The steel twin-screwgunboat was 188 ft.long, had a 12.5-ft.draft and could cruiseat 14 knots. Her most

powerful gun was a18 ft-8 inch breech-loader able to hurla cannon ball 7,500yards. She was usedin the Boxer War inChina, and in WorldWar I. In 1912, herbow was heightened

and the heavy gun removed. She sunk in1943 by accident. Figure 5 also shows thedeep-water harbor with the concrete blocksystem used to maintain the tidal rangeand times in the reef despite the harborexcavations.

Access to the coral cay was facilitatedby the construction of a deep-water harbor.Figure 3 shows the wooden gantry previ-ously used to transfer safely people and

supplies from the outer reef to the lagoon.

INTERNET LINKS

Photographs of Coastlines of Australiahttp://www.uq.edu.au/~e2hchans/photo.html#Coast_Australia

Heron Island Walk Abouthttp:/ /www.walkabout.com.au/loca-tions/QLDHeronIsland.shtml


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Sand Back-Passing with Land-Based Equipment,

A Cost-Effective Approach For Beach Restoration

By

Stuart Chase, P.E.Tetra Tech EC, IncStuart, FL 34994

[email protected]

ABSTRACT

One of the most significant challenges facingbeachfront coastlines is cost-effective nourishmentof eroded beaches where there is a history of con-tinued sand loss. This paper presents a conceptual,innovative sand back-passing beach restorationsystem that utilizes only land-based equipmentthat is completely mobile and adaptable to anybeach shoreline configuration. The system canretrieve accreted or shoaled sand anywhere withina five-mile shoreline distance of the beach to berestored, and within approximately 400 ft offshoreof the mean water line. This system can reduce thecost of beach restoration to approximately $6.50 to

$8.50 per cubic yard (cu yd), and can mitigate en-

INTRODUCTION

One of the most significant challeng-es facing coastal environments,especially beachfront coastlines, is

cost-effective beach restoration of erodedshorelines where there is a history of con-tinued erosion. Typically, beach restorationinvolves either the mobilization of largehydraulic dredges to pump sand from anoffshore borrow area or the utilization of atrucking operation to transport sand from

a distant upland source of beach-qualitysand to the eroded beach area.

These typical methods are costly. Dredgeplacement of beach sand can cost $9-$10per cubic yard (cu yd), including dredgeplant mobilization and demobilization,or more, for sand placement quantitiesof 300,000 to 500,000 cu yd or more.Truck transport with mechanical place-ment of beach sand can cost $15-$20per cu yd, depending on the distance ofthe upland beach sand source from theimpacted beach area and the cost of sand

at the sand source. These typical methodsalso raise environmental concerns such asdisturbance of potential offshore borrowarea bathymetry and its impact on marinebiota with offshore dredging, and air qual-ity impacts and traffic congestion with atrucking operation.

Approved offshore borrow areas mayalso be too far from the target beach areaor its sand may be finer than the sand at thetarget beach area, thus adversely impact-ing performance of the target beach. The

vironmental concerns with other beach restorationmethods. The system is best suited where erosionis a continual problem, and where sand needs to beplaced annually or periodically. The range of costeffectiveness for this system is limited to betweenabout 30,000 cu yd and 200,000 cu yd annually.Case histories of two sand bypassing transportmethods using land-based equipment based on thesame general concepts as the sand transport systempresented herein are discussed.

ADDITIONAL KEYWORDS: Beach nourish-ment, sand back-passing, land-based equipment,agitator slurry pump, booster pumps. Article re-ceived: 28 March 2005, Revised and Accepted: 8

February 2006.

land-based equipped sand back-passingsystem proposed in this article (and re-ferred to as the sand back-passing system)involves recycling eroded sand that hasaccreted at downdrift beaches by pumpingthis accreted sand back up-drift to restorethe eroded shore. With this system, costcan be reduced to between $6.50-$8.50per cu yd (including mobilization anddemobilization); environmental impactsare minimized; the quality of the sandrecycled is good; and configuration of thesystems elements can be adjusted to meetconditions of any type of beachfront shore-line. In addition, existing sand resourcesare used to the maximum extent possiblewithout acquiring new sand resources,which results in better sediment resourcemanagement. As an additional use of thissystem that cannot be accomplished withtraditional sand trucking, barging or dredg-ing (without an available offshore borrowarea), sand can be pumped to remote loca-tions such as islands or wetlands, with novehicular or navigable approaches, as partof ecosystem restoration activity.

SAND BACK-PASSINGSYSTEM APPLICATION

The sand back-passing system is notintended for a one-time use, but is bestsuited where erosion is a continual prob-lem and where sand needs to be placedannually or repetitively, between longerdurations. The range of cost effectivenessis limited to not more than approximately200,000 cu yd annually (which would takeapproximately four months to place), nor

less than 30,000 cu yd annually (whichwould take approximately one month toplace). For placement volumes of morethan 200,000 cu yd, use of a hydraulicdredge starts to become more cost-effec-tive on a total cost per cubic yard basis,including placement and mobilization anddemobilization. For placement amounts ofless than 30,000 cu yd, a truck operationwould be more cost-effective.

For this sand back-passing system to be

functional, a shoreline/surf zone source ofshoaled or accreted sand must be presentwithin approximately 4.5 mi. of the beacharea to be restored, due to pumping restric-tions, and within approximately 100-300ft seaward of the mean high water line(depending on the steepness of the beachforeshore slope), due to crane reach andsafety restrictions. Crane reach could beextended up to an additional 100-200 ftseaward by constructing a steel sheet pile-lined and sand-filled supporting platform,extending seaward for 100-200 ft.

Typically, sand eroded from a specific

beach locale stays within the 4.5- to 5-mipumping restriction for many months orshoals onto a more long-lasting accretedarea (or spit) within this retrieval zonelimit.

The LIDAR system can be used to ob-tain topographic/bathymetric informationfor quantity availability in the shoaledor accreted area near and just offshoreof the low water line within the retrievalzone limit. The LIDAR system soundingequipment, supported from an airplane orhelicopter, can plot the five-mile downdrift

swath of topography/bathymetry quite in-expensively (at a cost of $40,000-$50,000,but generally less if the five-mile area ofinterest is part of a more extensive area tobe surveyed).

The sand retrieval zone should ideally belocated near the end of a littoral cell or at alocation with zero net littoral drift. This isto avoid impacts downdrift of the accretionzone by recycling the accreted sand updrift.However, even if the sand retrieval zone isnot ideally located pertaining to its position


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in the littoral cell, the mobility of this sandtransport system can be utilized as often asneeded (based on monitoring the downdriftshoreline) to mitigate downdrift impacts.The system can alternately transport sandupdrift from the accretion zone to the tar-get beach for restoration or transport sanddowndrift to restore shorelines that have

been impacted by the recycling process. Inother words, a balance can be attained be-tween sand transport updrift and downdriftto mitigate downdrift impacts, especiallyby utilizing accreted sand in the retrievalzone upland and just outside the immediatelittoral zone.

CASE HISTORIES

This section highlights two essential-ly land-based sand transport (bypassing)systems that have been constructed, de-scribing current technology of land-basedsand transport systems including lessons

learned developed from assessments ofsystem performance. Comparisons to theland-based sand back-passing system willalso be made. Even though the projectgoals of these two case history systemsare different from the system presentedherein, the basic sand transport conceptsare similar.

The two case history systems are atOceanside, California, and at Indian RiverInlet, Deleware, both located at inletswhere shoaling at the channel entrance

and/or associated downdrift erosion is theproblem. By their very nature, the loca-tions of these systems were restricted tothe vicinity of the inlet, so mobility overlarger areas was not a goal as it is forthe system discussed here. However, theeffectiveness of the method that sand isretrieved from shoaled areas is a common

goal of both the case history systems andthe system presented here.

Oceanside, CA

The first case history involves the sandbypassing plant at Oceanside, CA, whichwas built and operated intermittently from1989 to 1993 (U.S. Army Corps of Engi-neers District, Los Angeles 1987; Weis-man, Lennon and Clausner 1996). Thesystem was terminated and removed in1997 due to lack of funding and technicaldifficulties. (A location map is shown onFigure 1.) This experimental system (withits use of jet pumps and fluidizers on alarge scale and in an oceanfront setting)was designed to remove sand that shoaledat the entrance channel from two loca-tions in close proximity of the inlet, andto pump the sand approximately two milesto eroding down-coast beaches. The goalwas to reduce the high cost associated withtraditional maintenance dredging.

The system consisted of sand bypassingfrom two locations in the vicinity of theinlet (Figure 1). The first location included

a fixed and buried eductor jet pump justupdrift (or north) of the north breakwa-ter that intercepted sand accreting at theupdrift fillet; it operated from Novemberthrough March, when the primary littoraldrift direction is from the north as it ap-proaches the entrance channel. This buried

jet pump was connected to a moored barge(pump platform) at a pile-supported piperiser structure located on the downdrift

side of the breakwater. A water supplypump on the barge fed water from theinlet, down the riser to the jet pump forslurry production; a booster pump on thebarge discharged the slurry produced atthe jet pump for transport under the in-let through a buried high-density plastic(HDPE) pipeline (12-in diameter). Theslurry pipeline then continued across thesouth jetty to a permanent booster pumpstation (operating with 400 hp) and thenon to the discharge points at two erodingbeach locations approximately two milesfurther downdrift (Figure 1).

The second sand bypassing location in-cluded two fixed and buried eductor jetpumps on the inlet side of the south jettywhich intercepted sand accreting at theentrance channel near the south jetty; itoperated from April through October whenthe primary littoral drift direction is fromthe south as it approaches the entrancechannel. These jet pumps were connectedto the same pump platform barge used atthe first location, but which was movedand moored to a second pile-supportedpipe riser structure located on the inletside of the south jetty. Like the first loca-

tion, a water supply pump on the barge fedwater from the inlet, down the riser to theeductor jet pumps for slurry production.A booster pump on the barge dischargedthe slurry produced at the jet pumps fortransport through a buried HDPE pipeline(10-in diameter), then over the south jettyand on to two eroding beach locations ap-proximately two miles further downdrift(Figure 1).

In order to increase the sand interceptarea at the second location where the ac-cretion area was more extensive, buried

fluidizer pipes in the entrance channelwere utilized. Approximately 150 ft of8-in diameter HDPE fluidizer pipe fed thenorth jet pump and approximately 200 ftof 10-in diameter HDPE fluidizer pipe fedthe south jet pump, both with water sup-plied from the pump barge (Figure 1). Theslightly sloped (toward the jet pumps) flu-idizer pipeline would hydrate sand to thesides and below the fluidizer pipe through1/8-in diameter holes spaced every twoinches to create a flow of sand along the

Figure 1. Map showing location and layout of the Oceanside, CA sand bypassingsystem.


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length of the fluidizer pipe, dropping intothe crater produced by the jet pumps, forintake into the jet pumps (Figure 2).

The jet pump has a nozzle which nar-rows the pipe flow and therefore increasesthe waters velocity, lowering the systemspressure at the nozzle and creating a vac-uum induced suction that draws sand intothe mixing chamber of the jet pump.

The target production rate for this sandbypassing system was 200 cu yd per hr.However, the sand transport rate actu-ally achieved averaged approximately 100cu yd per hr d

shore beach

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