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