presentation to mvc - march 2016 - martha's vineyard parke… · 1 charlie parker/abutters...

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CharlieParker/AbuttersPresentationtoMVCMarch24,2016

PresentationOutline

• Causeway–Heightofroaddecko Shadingo Flooding

• Guardrail–Height&density• Newskifflaunch–Mitigation

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Causeway:LowerRoadDeck&Railing

Objective• Lowerroaddeckbyasmuchas3’• Lowerguardrailfrom4’to2.5’Summaryofthebenefits:• Moreconsistentwiththeruralcharacterofthearea• Lessobtrusivewithlessimpactonabuttersandbeachgoers

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CausewayHeight–HistoryofDiscussion

• 12/4/14DraftRecommendation:4’-5’abovegrade• 2015TownMeeting:‘EverettPoolewithhandsintheair’

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AverageClearanceAcrossWetland=10.5’

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Shading

• Current proposal of 10.5’ under the road deck is excessive • 70%ofcausewaywidthfromgradetobottomofroaddeckwillmitigateshadingeffects: ‘Bridgeswithheight/widthratiogreaterthan0.7,didnothaveameasurableeffectonprimaryandsecondaryproductivity.’NCstudy‘EffectsofShadingfromBridgesonEstuarineWetlands’,June2005,pageiii.

• Keymeasurementisfromgradetothebottomoftheroaddeck • Usingthe70%ratio,8.4’fromgradetobottomofroaddeckisneededtomitigateshadingeffect

• Thisallowsforareductionofleast2’inheight• Conservativebecausebridgeisorientedfromnorthtosouth

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ShadingEffectsat11’Elevation(vs.13’)

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Flooding/Hydraulics

• Waterlevelinpondhasnotexceeded1.5’abovecurrentlevelsinceatleast1950(recordsfromRegenhome)

• Centerpointofcausewayis180’fromobservedmeanhighwater• Westernend-pointisbehind19’glacialbank(MoneyHill)

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CausewayRailing

RailingonMenemshacausewayislighter,more‘seethrough,andlessobtrusive.

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GuardRailingRecommendation

• Guardrailsuitableforvehiculartrafficoncountryroad• 15mphspeedlimit• 2.5’high,wood,posts8’apart,2x6rail.

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SkiffLaunchTwoobjectives:

• Separatekayaklaunchfromnewskifflauncharea• Mitigationforeffectsofadditionaltrafficfromnewskifflaunch

• ‘Lawofunintendedconsequences’:

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ProtectionofCoastalDuneandBarrierBeach

o Newfencingtoprotectcoastalbanknexttoskifflauncho Gateforskifflaunch(similartoAquinnah)o Signagetoprohibitpeoplefromcrossingcoastalduneo Simpleropefenceatedgeofdunebypublicbeach