HomeMy WebLinkAboutBaxter Road Homeowners 2013_11_12_201404011027319918November 12, 2013
Mr. Ernest Steinauer, Chairman
Nantucket Conservation Commission
2 Bathing Beach Road
Nantucket, MA 02554
Re: Baxter Road Conservation
Dear Chairman Steinauer and Members of the Conservation Commission:
Thank you for all of your effort in working towards a solution for protecting Baxter Road from further
erosion this winter season. We are hopeful that you and your fellow commissioners will unanimously
approve the installation of a geotube at the toe of the bluff in the most threatened areas of Baxter Road
in tomorrow night’s meeting. While many of us are not on-island to attend, we will be following the
outcome very closely. The current design represents an environmentally accepted "soft solution" that
has been used in many coastal communities throughout New England and Mid Atlantic states. It will be
closely monitored, and it can readily be removed if adverse impacts are observed.
New Jersey, Florida, Maryland and California spend hundreds of millions annually to protect their
coastal communities. There is no “one size fits all” solution; different applications have been used in
various coastal environments. Nantucket’s coastal problems are not unique, and neither should be our
responses. Geotubes have been proven effective throughout the east coast of the US, including post
Super Storm Sandy (see attached). With the strong support of the Town's Board of Selectman, we ask
that you and your fellow commission members work expeditiously and constructively with the Town
staff to implement this Town co-sponsored project in the days ahead. Time is critical with winter season
upon us.
Our project has the benefit of using private dollars to protect a Town of Nantucket asset from erosion
on a remote beach. Failure to approve this project will likely result in the collapse of Baxter Road,
which will be at a significant cost to Nantucketers, and will only increase over time. A collapsed road
will also serve as a costly precedent for the Town, and the Commission will have missed an opportunity
to try an environmentally sound alternative. We encourage you to prevent this from occurring on your
watch as Commission Chair.
Mr. Chairman, it is up to you to show leadership on this issue and approve a project that can help
solve future coastal problems for the Town, and its assets. Other towns have taken steps to permit
projects (see attached letter from Town of Southampton) to battle erosion, we remain hopeful that the
Town of Nantucket is not an “outlier” in addressing a widespread problem.
Respectfully submitted,
Northern Baxter Road Homeowners
David & Dorothy Bailey Elizabeth Claudy John DeAngelis Martha Lyn Dippell
Steve & Erin Freeman Sam & Ann Furrow Daniel Korengold Bill & Marilee Matteson
Margaret McQuade Patrick & Molly Ryan James & Deborah Walker Alexander & Laurie Webb III
The Judy Family Loretta Yoder
January 2013 |53www.esemag.com
At the end of October, 2012,
Hurricane Sandy hit the
Caribbean area and subse-
quently the eastern coast of
the United States with devastating force.
Sandy claimed dozens of lives and
caused damage amounting to $30 billion.
TenCate Geotube®containers had been
placed in the dunes in parts of the coast
of New Jersey, which restricted the ero-
sion of the shoreline there.
To help with dune restoration, dune
dikes with TenCate Geotube containers
were constructed along the New Jersey
shoreline, starting in the 1990s. In 2010,
a total of 1.47 km of these containers had
been installed. This afforded places such
as Ocean City, Sea Isle City, Beach Haven
and Atlantic City optimal protection
against hurricane forces. No needless pre-
caution, as it turned out recently. The tu-
bular containers in the row of dunes
managed to withstand the pounding waves
that buffeted the coast as Sandy struck.
The tubes lived up to expectations, even
though part of the dune was washed away.
In September, 2008, 5m-high waves
generated by Hurricane Ike, one of the
predecessors of Sandy and Isaac, which
also hit in 2012, ravaged the coast of
Galveston, Texas. The damage remained
reasonably restricted thanks to the row of
Geotube containers along the shoreline.
people, destroyed 4,500 houses and left
100,000 people homeless. Where other
companies in the region decided the future
still lay in cotton and other traditional fibers,
TenCate accepted the challenge posed by
the Dutch authorities and developed a tech-
nical textile for use in marine structures.
For more information, E-mail:
j.mckay@tencate.com
Hurricane Irene hit the East coast in Au-
gust 2011; containers installed at Beach
Haven and Ocean City held up and pro-
tected properties.
TenCate’s long history with marine con-
struction and shoreline protection applica-
tions started with the development of nylon
bags just after the major flood disaster that
hit the south-west of the Netherlands in
1953. This catastrophic event killed 1,850
Geotube technology protects New Jersey
shoreline from Hurricane Sandy
> Water & Wastewater Systems
> Stormwater Treatment & Management
> Modeling
> Hydrologic & Hydraulic Analysis
> Environmental Planning
> Distribution, Collection, Treatment
> Hydrogeology
Sustainable Solutions
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Ocean City’s beach after Hurricane Sandy.
EcosystemsJanuary 2013 D5_ES&E 13-01-31 9:45 PM Page 53
AmTTClTOWNOFTelephone:(631)283-6055ftNNAIIWONEJIOLSTOUTHAMPTONfax:(631)287-5708Sttpervisor116Hampton Road,Southampton,NY11968athrofle-holst@Southamptontownny.govSeptember27,2013JeffreyBIaudoTheRelatedCompanies60ColumbusCirFL19NewYorkNY10023RE:313 DuneRdDearBeachErosionControlDistrictPropertyOwner,ThebeachrenourishmentprojectfortheSagaponack,BridgehamptonandWaterMillshorelineisnowunderway!EquipmentandpersonnelfromtheGreatLakesDredgingCompanyhavebegunarrivinginthearea,anditisanticipatedthatactualsandplacementwillbeginbymid-October.Inordertokeepyouinformedaboutwhattoexpectduringandaftertheconstructionphase,pleasefindenclosedaseriesoffactsheetspreparedbytheproject designersatCoastal ScienceandEngineering.ThisinformationwillalsobepostedontheTown’swebsiteatwww.southamptontownny.gov/becdalongwithroutineupdatesontheconstructionschedule.Ifyouhaveanyquestions aboutthisinformationortheprojectingeneral,pleasedonothesitatetocontactmyofficeat 631-283-6055.Sincerely,AnnaThrone-HoistSupervisor
Sagaponack/Bridgehampton—WaterMill—TownofSouthampton(NY)BeachNourishmentProject—September2013FACTSHEET#1—Scale,Schedule&MilestonesTheTownofSouthampton,incoordinationwiththeErosionControl Districts(ECD)ofSagaponackandBridgehampton—WaterMill,hasreceivedpermitsandbidstocompleteamajorbeachnourishmentprojectbetweenSeptemberandDecember2013.ThisisthefirstofaseriesofFactSheetsthatoutlinesthescopeandscheduleoftheprojectanddiscusseshowthebeachwillbewidened.FactSheetsalsodiscussimpactsofconstructionandfuturechangestoexpectalongtheoceanfront.Whereistheproject?TheprojectwillextendfromTownlineRoad(Sagaponack)totheTownbeachatFlyingPointRoad“3/2milewestofthe entrancetoMecoxBay.TotalLength:5.7milesWhatisthecostoftheproject?TheTownreceivedbidson July10,2013.Basedonthefixedconstructionbudgetofapproximately$22,143,000establishedbyreferendumsateachECDandtheTown’smatchingfunds,atotalof“2,573,000cubicyardswillbeplacedalongthebeach.Thevolumeofsandthatcanbeaccomplishedwithinbudgetisabout20percentgreaterthantheTownanticipated,priortothereferendums,duetofavorablebids.Whatwilltheprojectdo?Theprojectwillwidenthebeachanaverageof75—100feetbyaddingnew sandtothebeachzone.Sandwillbeobtainedfromadeepwaterareaonemileoffshore.Initially,theconstructedbeachwillbebuiltwiderthanthisaveragesoasto controlthesandplacement.Wavesandtideswillthenreshapetheprofileofthebeach,shifting sandtowardtheduneandasignificantvolumetotheouterbarasillustratedbelow.Aftertheprofile“equilibrates,”thenewbeachwillchangewiththeseasonmuchlikeanynatural beach.HowdoesthesizeoftheprojectcomparewithpreviousbeachrebuildingeffortseastofShinnecockInlet?Recordsshowtherehavebeen“'14nourishmenteventsalongSouthamptonandEasthamptonbeachessincethe19405,totaling“2.9 millioncubicyards.The Town’sprojectwillnearlyequalthesandvolumeofallprioreventsintheregion.Whenwillconstructionbegin?Thecontractorstartedmobilizationaround20Septemberandwillneed2-3weekstoassemblepersonnel,equipment,pipeline,andsupportingvesselstothejobsitebeforethedredgecanbeginwork.WenowanticipatetheearliestsandplacementalongthebeachwilloccurduringtheweekofOctober14thHowlongwillittaketoplace‘2.5millioncubicyardsonthebeach?Aboutthreemonths.Thiswilldependonweatherandthenumberofdredgesused.Aroughguide forproductionbyoneocean-goingdredgeis1millioncubicyardspermonth forthetypeofsandandpumpingdistancefromtheborrowareatothebeach.Ifsignificantweatherdelays occur,thecontractorhasadditionaldredgesavailabletosupplementconstruction.Whatisthelifeexpectancyoftheproject?Overtenyearsundernormalconditions.Thehistoricalsandlossratehasaveragedabout4cubicyardsperfootofshorelineperyear.Theprojectwilladdanaverageof‘85cubicyards perfootofshoreline.Ifweassume,conservatively,theaverageerosionrateincreasesaftertheprojectby50percentto“6cubicyardsperfooti,eryear,thenatleast30percentofthenourishmentsandwillremainaftertenyears.Thelostsandwillhavemigratedwestandeast,helpingreducetheaveragerateoferosionalongneighboringvillages.Giventhelimitedhistorical surveydataavailablefortheprojectarea,predictionsoflongevityareuncertain.ThatiswhytheTowniscommittedtomeasuringhow muchsandremainsintheprojectareaeachyear.TheresultsofannualsurveyswillbepostedontheTown’swebsiteforindependentreviewandjudgment.TheTownwillnotknowthescheduleforsandplacementalongspecificpropertiesuntiltheprojectisunderway.Atrackingmap oftheoceanfrontwillbeavailableontheTown’swebsitetoassisthomeownersindetermining theapproximateweektoexpectworkinaparticularsectionofbeach.
KEYDATESTheTownreceivedbidsfromtwodredgingcompanies.GreotLokesDredge&DockCompony(GLDD—Ookbrook10JulyIllinois)submittedthelowestbid.Thebidwos‘3percentbelowtheengineer’sfinolprojectestimote.3AugustTheTownreceivedthefederal permitwhichwasthefinal regulatory requirementtoimplementtheproject.TheTownawardedthecontracttoGLDDandisawaitingperformancebondsandrelatedcontractualdocuments5Augustbeforeissuing aNoticetoProceedwithconstruction.Apre-canstructionmeetingconvenedatTownHallwithrepresentativesoftheTown,contractor,andproject15Augustengineer.EarliestdatepermittedbytheStateofNewYorkandUSArmyCorpsofEngineersforconstructionactivities.1SeptemberNote:ThecontractorisfinishingaprojectinConeyIslandduringthemonthofSeptemberandbeganmobilizingsupportequipmenttotheSouthamptoninlateSeptemberforaconstructionstartinmid-October.31DecemberLatestdateallowableforconstructionunderthecontractwiththeTown.TFollowingis alinktoresultsofannualmonitoringtwo yearsaftertheNagsHead(NC)nourishmentproject:[httn://www.nagsheadnc.gov/vertical/sites/%7BB2cBo823-Bc26-47E7-8656-37D1995754E1%70/uoloads/NHBeachConditionSurvey-Memo(07-26-2013).pdf].—ThenextFactSheetsdiscussthespecificdredgingoperationsandimpactsofconstruction.———60f1InitialConstructedProfileBeachNourishment÷7ftConstructedBermNormalAdjustedProfileAt1-2YearsPostProjectAccretionPostProjectErosionNotToScale
Sagaponack/Bridgehampton—WaterMill—TownofSouthampton(NY)BeachNourishmentProject—August2013FACTSHEET#2—BeachNourishmentOperationsBeachnourishmentissimplytheadditionofqualitysandtothebeachforpurposesofwideningitandreplacingsandthathasbeenlostovertime.TheSagaponack—Bridgehampton—WaterMillprojectwillbeconstructedusingocean-goingdredgesthatpumpsandfromanoffshore“borrowarea” directlytothebeach.Thisisgenerallyconsideredtobethemostefficientandleastdisruptivemethodforrebuildingbeaches.FactSheet#3describesthedredgingoperationandassociatedshapingofthenewsandonthebeach.FactSheet#4discusseshowtheprojecthasbeendesignedtominimizeadverseenvironmentalimpacts.Whattypeofdredgewillbeused?Thecontractor(GreatLakesDredge&DockCompany—GLDD)planstomainlyusethecutter-suctiondredge,Illinois.TheIllinoisisocean-certifiedbytheUSCoastGuardandoneofonlyadozenorsodredgesintheUnitedStatesthatarelicensedtoworkoffshore.Howdodredgeswork?Cutter-suctiondredgesanchoroveraborrow areaandlowera“ladder”supportingthedriveshaftfora12-foot-diametercutterheadandanintakesuctionpipe.Thedredgesfingssidetosidebymeansofanchorcablesandwincheswhilethecutterheadspins,mobilizingthesand.Hydraulicpumps suctionthesand/waterslurryoffthebottomandsenditshoreward througha30-inch-diameterpipeline.Howwillthesandreachthebeach?GLDDwillplacelongsectionsofsteelpipeontheoceanfloorbetweeneachofthethreeborrowareaspermittedfortheproject.Thelandwardendofthe“submerged”pipewillterminateattheedgeofthedry-sandbeach.A“Y-valve”willbeattachedatthatpointandusedtocontrolthedirectionofflow.Sectionsofsteelpipe40feetlongwillbeattachedtothevalveanddirectedalongthebeach.Asprayerheadwillbeplacedattheendofthe“shore”pipetodistributethesandslurry overawiderarea.Dependingonthelocalitywithintheprojectarea,thenourishmentsandwillhavetraveled between about1to3milesfromtheunderwaterborrowareatothedischargepoint.Howwillthesandbeshaped?Theslurryofsandandwaterwilldischargeparalleltotheshorelineinthevicinityofthelow-tidemark.Sandwillsettlerapidly whilethewaterandfineparticleswillmixwiththewatercolumn.Assand moundsaroundthepipeend,bulldozerswillshapeittothenaturalcontoursofthebeach. Personnelonshorewillusereferencestakesandelectronicsurveysystemstocontroltheshapeanddimensionsoftheproject.Assectionsarecompleted,more lengthsofpipewillbeadded.Willconstructionproceed continuouslyalongthebeach?No.The sizeoftheproject requiresmultiple“landingpoints.”Workwillproceedinonedirectionfromagivenlandingpoint forseveralthousandfeet.Thentheshorepipewillberemoved,and workwillproceedintheotherdirectionfromthesamelandingpoint.Whenallworkplannedforaparticularlandingpointandpipelinelengthiscomplete,GLDDwilltemporarilystoppumpingsandandrelocatethesubmergedpipelinetoanewlandingpoint.Because workproceedsfrommultiplelandingpoints,therewillbetemporarygapsasconstruction progressesbetweencompletedsectionsandtheactiveworkarea.ThisisthemainreasontheTownofSouthamptoncannotalertpropertyownerswellinadvanceoftheexpecteddateofnourishmentalongaparticularproperty.Whatwillbethenormalareaofimpacteach day?Themainareaofactivityonthebeachwillbea300—800ftcorridoraroundtheendofthepipeline.Abackbeachstripof drysandwillbeaccessibletobeachgoersforuninterruptedwalksalongthebeach.However,forsafetyreasons,theconstructionareawillbecordonedoff,andasafetyinspectorwillbestationedtoalert beachgoers.Asthenourishmentprogresses,completedsectionswillbereopenedandusableimmediately.Thesecurityareawillshiftwiththedischargepoint.Lengthsofshorepipenecessarilywillremaininplaceoverthenew beachwhileaparticularreachisconstructed.Thecontractorwillprovidefrequentsand rampsoverthepipelinesobeachgoerscanenjoytherestofthebeach.Atime-lapsevideooftheNagsHead(NC)beachnourishment projectillustratesthe“roll-out”ofanewbeachatonelocalityovera24-hourperiod(http://www.youtube.com/watch?v=tGs-OUli9is).—ThenextFactSheetdiscussestheimpactsofconstruction.—
Sagaponack/Bridgehampton—WaterMill—TownofSouthampton(NY)BeachNourishment Project—August 2013FACTSHEET#3—ImpactsofConstructionBeachnourishmentisdisruptive.However,thecommunitymaybesurprisedtoseehowrapidlysuchprojectscanbecompletedanddisruptionminimizedtobeachgoersandtheenvironment.ThisFactSheetdiscussessomeofthefrequentlyaskedquestionsaboutimpacts.Howlongbeforethenewbeachcan beused?Immediatelyupon removaloftheconstructionflagsandsafetyfencefromtheactiveworkarea.Testsshowthereisnegligible mudintheplannedborrowarea.Thenewsandwillsettleanddrain rapidly,leavingausablebeachthatwilladjusttowavesandtidesjustlikeanaturalbeach.Willconstructionactivitiesoccuratnight?Yes.Constructionwillrun24—7soastomaximizetheproductionand efficiencyofthedredgeatconsiderablesavingstothecommunity.Nighttimeconstructioncanbeseeninthetime-lapsevideooftheNagsHead(NC)beachnourishmentproject(htto://www.youtube.tom/watch?vtGs-OUli9is).Hownoisywillconstructionbe?Noiselevelswillbehighintheimmediatevicinityofthedischargepoint,mainlyduetotheactivityofbulldozers.Dieselenginesand backupbeeperswillbeinuse.Themainareaofnoisewillextend‘500feet(ft)fromthedischarge point.Howlongwillittaketocompleteworkalongmysectionofbeach?Typicalproductionisabout300ftofbeachperdaysotheactiveworkareawillmovequicklypasteachproperty.However,ownersandguestsshouldexpect disruptionforafewdaysbeforemostoftheequipmentandsafetyfencearerelocatedtoanothersectionofbeach.Whatwillthenewsandlooklike?The“borrow”sandfromoffshorewasbeach sandthousandsofyearsagowhensealevelwaslower.Ithasasimilarcolorandtextureastheexistingsandonthebeach.Itwillbewetandslightlydarkerwhenpumpedintoplace,butweexpectittodryoutandbleachrapidlysothatitbecomesindistinguishablefromtheexistingbeachsand.Willthewaterbemuddy forawhile?Theoffshoresandcontainsatinyfractionofmudandorganicmatter.Thisfinematerialwillwashoutwiththeslurryasnewsandsettlesonthebeach.Therewillbehigherturbidityinthewaterclosetotheactivedischargepointoveradistanceofseveralhundredfeet.Turbiditylevelsareexpectedtoremainthesameasambient500ftfromtheactiveconstructionarea.Howlongwillthepipelineblockmysectionofbeach?Thepipelinewillextenduptoonemilealongthebeachbeforeitisdismantledandrelocatedtoanothersection.Dependingonthelocationofyourproperty,itmaybeinplaceforonetothreeweeks.Asnewsectionsofbeacharefilledandreopened,sand rampswillbeplacedoverthepipelinetoprovideaccesstothewater.Willthepipelinedamagemydunes?Thepipelinewillrunalongthemiddleofthedry-sandbeachwellawayfromthedunesandthesurf.Therewillbeawideareaofbeachtousebetweenthepipelineandthewater.Isthepipelinedangerous?Yes.Itwillbedischargingaslurryofsandandwaterunderhighpressure.Suddenleakscanoccurandshootsprayintotheair.Beachgoersshouldonlycrossthepipelineatthesand rampsandnotplaceblanketsandchairsclosetothepipe.Whatarethepublicsafety measuresduringthe project?Thecontractorwillstation safetypersonnelateitherendoftheactiveworkarea.Temporaryfencingandflaggingribbonwillcordonoffthearea.Insidethesafetyfence,allworkersandauthorizedvisitorsmustwearhardhats,safetyglasses,reflectivevests,andsteel-toedfootwear.TheTownwillalsohavepoliceandemergencypersonnelonstandbyto respondimmediatelytoincidents.Willthepublicbeabletowatchconstruction?Yes.Thebeachwillbeopenduringconstructionandwillbeaccessiblealonganarrowbackbeach corridorintheactiveworkarea.Existingbeachaccesseswillremainavailable,butsomeparkingspaceswillbecordonedoffforthecontractor’ssupportequipment.Pleaseusecaution aroundequipmentandpipesstoredonthebeach.—ThenextFactSheetdiscussesenvironmentalimpacts.—TheTownwillnotknowthescheduleforsandplacementalongspecificpropertiesuntiltheprojectisunderway.AtrackingmapoftheoceanfrontwillbeavailableontheTown’swebsitetoassisthomeownersindeterminingtheapproximateweektoexpectworkinaparticularsectionofbeach.
Sagaponack/Bridgehampton—WaterMill—TownofSouthampton(NY)BeachNourishmentProject—August 2013FACTSHEET#4—EnvironmentalImpactsThisFactSheetdiscussessomeoftheenvironmentalimpactsoftheproject.Whenproperlyperformed,beachnourishmentisnodifferentthannaturalaccretionandsimplyfeedsnewsandtothebeach/dunesystem.HowwilltheSagaponack—Bridgehampton—WaterMillprojecthelptheenvironment?Inseveralways.First,newbeach-qualitysandwillfeedthelittoralsystemandoffsetdecadesofchronicerosion.Second,theextrasandvolumewillwidenthebeachandlessenthedegreeofduneerosioninstorms.Third,excesssandwillnaturallyrebuilddunes,furtherburyemergencysandbags,andallow newvegetationtopropagate.Awide,dry-sandbeachafternourishmentisafavoredhabitatforcertaintarespecies(suchasseabeachamaranth)andpipingplovers.Willthenewbeachproduceunpleasantodors?No.Theoffshoreborrowmaterialisalmostentirelysandwithminorshellfragments,whichsmellslikethesandinthesurfzone.Dredgedmaterialfromharborsandestuariesoftencontainshighproportionsofmudandorganicmatterwhichwillreleasehydrogensulfideandotherodorsassociatedwithdecayingmatter.Thiswillnotbethecaseduringtheproject.Willtheprofileofthebeachremainthesame?Notinitially.Thesandwillbepumpedintoplaceatanelevationthatisamid-rangeofthenormaldry-beachlevel.Wedothissothatminorstormtideswillwashoverthenewbeachandhelpmixthenourishmentsandwiththenativesand.Washoverswillpushsomesandtowardthedunesandpositionitfavorablyfordunegrowthbywinds.Meanwhile,theseawardedgeofthedrybeachwillretreatlandwardastheslopeadjusts.Somesandwillshifttowardtheouterbarinshallowwater.Thissandredistributionisimportantbecauseitresultsinanewbeachwithslopesandsurfbreakssimilartotheexistingbeach.[Seegraphicwhichshows“cut-away”profilesofthebeachbeforeandafternourishment,andadjustmentofthenewbeach.]Willthenourishedbeacherodefasterthanthebeachhasinthepast?Toasmall degree.Whenthereisaprotrusionoftheshorelineintotheocean,relativeto adjacentsectionsofbeach,itbecomesafocalpointforwavesandsandredistribution.Thisisnature’swayofproducingthelongstrandbeachthatexistsbetweenMontaukandShinnecockInlet.Theprojectwillcreateawiderbeachandthereforetendtogiveupsandtoadjacent,lesshealthysectionstotheeastandwest.Thisredistributionwilloccurgradually,andtheTownplanstomonitorlosseseachyearanddeterminehowmuchsandremainswithintheprojectarea.InitialConstructedProfileBeachNourishment-+7ft-
--ConstructedBermNormalAdjustedProfileAt1-2Years‘ftPostProjectAccretionIPostProjectErosionNotToScale
Whyistheprojectbeingconstructedinthefall?Thisisthetimeallowableunderthepermitsinconsiderationofprotectionofthreatenedspeciessuchasthepipingplover.Thisschedulewillalsoprovideaprotectivebeachwhich canabsorbandadjusttowinterstormsandtakeonanaturallookpriortonextsummer.Whatwillhappentotheorganismslivinginthebeach?Nourishmentburiessome“benthic” organismslikesurfclamsandwormswhicharelessmobile.However,thespecieslivinginthesurfzonegenerallyhaveshortlifecyclesandareadaptedtohigh-energy conditionsandtheconstantchangesinthesandlevel.Assoonastheprojectisfinishedinasection,beach organismswillbegintopopulatethenewbeach.Studieshaveshownthatnourishmentprojectswhichmatchthesandtexturesofthenativebeachtendtorapidlyrecovertheirpopulationoforganisms—inweekstomonths.Willdredgingleaveabigholeoffshoreandproduceabiological“deadzone”?No.Sandwillbedredgedfromwaterdepthsbetween45and50feetdeep aboutonemileoffshore.Themaximumexcavationpermittedis 7feetbelowtheexistingbottom.Thesedimentsbelowthislevelaresimilarinsizeandqualitytotheborrowsedimentsandaregenerallyfreeofmud.Dredgingwill,ineffect, removeashallow“plateofsand”acrossmanyacres,leavingsimilarsandsinplace.Waves andcurrentswillmaintaincirculationandwaterquality (particularlydissolvedoxygen)acrosstheborrowareaandalloworganismstoquicklyrecolonizethedredgedarea.Willtheprojectaffectsurffishingoroffshorespecies?Nottothedegreetheseasonoftheyearaffectsfishing.Theimpactonfisheriesishighlysite-and-seasondependent.Offshoredredgingmobilizesorganismsandexposesfreshsubstrate,which caninitiallyattractsomefishspeciesbecauseoftheavailabilityoffood.Ontheotherhand,fishgenerallyavoidtheimmediatevicinityofthedredgeanddischargepointsduetoelevatedturbidity.However,turbidwaterswillbelocalizedandshort-lived,returningtoambientconditionssoonafterpumpingstops.Weexpectsurffishingandtrollingforfishovertheborrowareato remainasunpredictableastheseactivitieshavebeenforalltheyearsbeforeanybeachnourishmentactivity.—ThenextFactSheetdiscussesimpactsofstorms.—
Sagaponack/Bridgehampton—WaterMill—TownofSouthampton(NY)BeachNourishmentProject—August2013FACTSHEET#5—StormImpactsStormswillaffectanybeachnourishmentprojectjustastheymodifynaturalbeaches.ThisFactSheetdescribessomelikelyimpactsandwaysnourishmentwillmitigate damages.Whatwillhappenwhenastormimpactstheprojectarea?Thebeachwillabsorbthehighwavesandwillchangeshape.Contrarytoconventionalwisdom,mostofthesandwillremaininthe“beachsystem,”butlargequantitieswillshiftfromtheupperbeachandmovetowardtheouterbar.Ifthestormisofmoderateintensitysuchasatypicalnortheaster,littlesandwillbeerodedfromtheforedune,butifamajorhurricaneimpacts,thestormsurgewillallowwavestoreachtheforeduneandcutitaway.Ineithercase,sanderodesfromthevisiblebeachandisdepositedinshallowwater.Thenetresultisaflatterprofilecomparedwiththenormal“fair-weather”profile.Whathappenstothebeachafterstorms?Thevisiblebeachgraduallyrebuilds.Normalwaveswillreshapetheprofile,pushingthesandlandwardandrestoringthedrybeach.Theunderwaterprofilewillalsotendtorebuildaprotectivebar.Thisprocessofprofileadjustmentwilloccurover severalweekstomonths.Dunerebuildingwillalsooccur,butataslowerrate.Thestorm/post-stormprofileresponseisreferredtoasthe“beachcycle.”Howmuchnourishmentwillbewashedcompletelyawayinstorms?Itdepends.ForarelativelylargeprojectlikeSagaponack/Bridgehampton—WaterMill(5.7miles,‘2.6millioncubicyards),itwouldnotbeunusualtolose25percentofthenourishmentinamajor,slow-movingstormsuchasHurricaneSandyorthe1962AshWednesdaynortheaster.Bothstorms producedstrongcurrentstothewestwhichistheprocessthatcarriessanddowncoastawayfromtheprojectarea.Butfast-movinghurricanesoften producemorecross-shoresandtransport,meaningthesandstaysmostlywithintheboundariesoftheproject area.Fairweatherreturnssandtothevisiblebeach,limitingthenetloss.Howdoesprojectlengthaffectthesandlossesduringstorms?Longerprojectsarebetter.Infact,projectlifeincreasesgeometricallywithlength.Forexample,afour-mile-longprojectwillgenerallyretainsandfourtimeslongerthanatwo-mile-longproject,allotherfactorsbeingequal.SomerecentprojectsalongFireIslandlosthighproportionsofMostofthesandlossinvolvedspreadingofnourishmentsandtoadjacent,unnourishedsectionsoftheNationalSeashore.Ifsandislostinamajorstorm,canitbereplacedwithlittlecost tothecommunity?Yes,providedthestormreceivesafederaldeclarationofdisasterandthelossesareproperlydocumented.TheprojectisengineeredandthereforeisexpectedtoqualifyforFEMApost-disastercommunityassistancegrants.Theseemergencyfundscanbeusedtoreplacesandlostinamajorstorm.Theerodedbeachwouldberenourished andrestoredtoitsconditionpriortothestorm.TheTownplansannualsurveys,asrequiredbyFEMA,todocumentthenourishmentvolumeremainingonthebeachpriortoacatastrophicstorm.FEMAdoesnotreimbursecommunitiesfornormalyearlyerosionlossesorlossesduetominorstorms.Willtheprojectreducedamagesduringstorms?Yes.Awiderbeachwillabsorbstormwavesbefore theyreachpeople’shouses.Awider,dry-sandbeachwillalsofeedsandtotheforedune,allowingittobuildvolumeandheight.Widebeachesplushighdunesequallessdamagetouplandandcommunityinfrastructure.Willtheprojectreducemyannualdunemaintenancecost?Itshould.Awiderbeachcreatesareservoirofsandthatgraduallyfeedsthedunesystem.Italsoallowstheannualcycleofwintererosionandsummeraccretiontooccurwithinthezoneofdrybeachwithoutimpactingthebackbeachzone.Presently,evenminorwinterstormscutawaythebeachuptothedune,makingitharderandmorecostlytomaintainprotectivevegetation.Arethereexamplesofbeacheswheretheduneshavegrownnaturallyafternourishment?Yes.TheVillageofWesthamptonDunesisoneexamplewheretheduneshavebecomebiggereachyearsincethefirstnourishmentinthemid1990s.AnotherexampleisBogueBanks(NC).Beforenourishment,thetypicalannualcostofdunemaintenancewas$2,000—$5,000perpropertywithupwardof350permitsissuedeachyearforbeachscrapingandwalkoverreplacement.Overthepastdecadesincenourishment,fewsandscrapingpermitshavebeenissued,andwalkoverpermits aregenerallyforlengthening,notrebuilding,damagedstructures.nourishmentbecausetheywererelativelyshort(1mile).