Update on the Town of Longboat Key's Permeable ... - fsbpa
Update on the Town of Longboat Key's Permeable ... - fsbpa
Update on the Town of Longboat Key's Permeable ... - fsbpa
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<str<strong>on</strong>g>Update</str<strong>on</strong>g> <strong>on</strong> <strong>the</strong> <strong>Town</strong> <strong>of</strong> L<strong>on</strong>gboat Key’s <strong>Permeable</strong>Adjustable Groins PerformanceDouglas W. Mann, P.E., D.CEFlorida Shore & Beach Preservati<strong>on</strong> Associati<strong>on</strong>February 14, 20131
2010 C<strong>on</strong>structi<strong>on</strong>01M042012DTOWN OF LONGBOAT KEY’S PERMEABLE ADJUSTABLE GROINS2
2010 Early Resp<strong>on</strong>se01M042012DTOWN OF LONGBOAT KEY’S PERMEABLE ADJUSTABLE GROINS3
Comparis<strong>on</strong> <strong>of</strong> <strong>the</strong> Islander Hot Spot2004 (3 years post 2001 nourishment) 2010 (4 years post 2005/2006 nourishment)01M042012DTOWN OF LONGBOAT KEY’S PERMEABLE ADJUSTABLE GROINS4
2011 C<strong>on</strong>clusi<strong>on</strong>s from <strong>the</strong> Initial M<strong>on</strong>itoring► <strong>Permeable</strong> adjustable groins show promise as a viable erosi<strong>on</strong> c<strong>on</strong>trolstructure.► From a beach management perspective, <strong>the</strong> groins in additi<strong>on</strong> to <strong>the</strong>nourishment are better at managing <strong>the</strong> sand resources thannourishment al<strong>on</strong>e.► If <strong>the</strong> north beach trends c<strong>on</strong>tinue, <strong>the</strong> groins may need to be adjusted toincrease <strong>the</strong> permeability to enhance bypassing.► Future m<strong>on</strong>itoring will c<strong>on</strong>tinue, enabling <strong>the</strong> <strong>Town</strong>, CPE, and FDEP todetermine any future acti<strong>on</strong>s in this area, which may include increasing<strong>the</strong> permeability <strong>of</strong> <strong>the</strong> seaward ends <strong>of</strong> <strong>on</strong>e or both groins.01M042012DTOWN OF LONGBOAT KEY’S PERMEABLE ADJUSTABLE GROINS5
Overview► 2011 shoreline trends► 2012 adjustment process► Effects <strong>of</strong> Tropical Storm Debby <strong>on</strong> <strong>the</strong> coastal processes► Future <strong>Town</strong> acti<strong>on</strong>s► Future PAG applicati<strong>on</strong>s01M042012DTOWN OF LONGBOAT KEY’S PERMEABLE ADJUSTABLE GROINS6
Locati<strong>on</strong> Map01M042012DTOWN OF LONGBOAT KEY’S PERMEABLE ADJUSTABLE GROINS7
Aerial Locati<strong>on</strong> MapNet Transport =50,000 toNet Transport =50,000 to 90,000 cy/yr.90,000 cy/yr.01M042012DTOWN OF LONGBOAT KEY’S PERMEABLE ADJUSTABLE GROINS8
Historical Shoreline Changes806040Shoreline Change (Ft/yr)200-20-40-600 1000 2000 3000 4000 5000 6000 7000 8000 9000Distance from FDEP R10 (ft)Jul 06 to Oct 09 North groin south groin01M042012DTOWN OF LONGBOAT KEY’S PERMEABLE ADJUSTABLE GROINS9
Initial 2010 Shoreline Resp<strong>on</strong>se806040Shoreline Change (Ft/yr)200-20-40-600 1000 2000 3000 4000 5000 6000 7000 8000 9000Distance from FDEP R10 (ft)Oct 09- Oct 10 Jul 06 to Oct 09 North groin south groin01M042012DTOWN OF LONGBOAT KEY’S PERMEABLE ADJUSTABLE GROINS10
18 M<strong>on</strong>ths Ground ViewNovember 201101M042012DTOWN OF LONGBOAT KEY’S PERMEABLE ADJUSTABLE GROINS11
2010-2011 Shoreline Resp<strong>on</strong>se80Shoreline Changes60Shoreline Change (FT/YR)40200-20-40-6010 11 12 13 14 15 16 17 18Pr<strong>of</strong>ile LinesShoreline Change Rate from 07/06 to 10/09 Shoreline Change Rate from 10/09 to 10/10GroinSouth GroinShoreline change 10/10 to 10/1101M042012DTOWN OF LONGBOAT KEY’S PERMEABLE ADJUSTABLE GROINS12
18 M<strong>on</strong>ths ObliquePhoto courtesy <strong>of</strong> <strong>the</strong> town <strong>of</strong> L<strong>on</strong>gboat Key, November 201101M042012DTOWN OF LONGBOAT KEY’S PERMEABLE ADJUSTABLE GROINS13
Overview► 2011 shoreline trends► 2012 adjustment process► Effects <strong>of</strong> Tropical Storm Debby <strong>on</strong> <strong>the</strong> coastal processes► Future <strong>Town</strong> acti<strong>on</strong>s► Future PAG applicati<strong>on</strong>s01M042012DTOWN OF LONGBOAT KEY’S PERMEABLE ADJUSTABLE GROINS14
Adjustable Elements01M042012DTOWN OF LONGBOAT KEY’S PERMEABLE ADJUSTABLE GROINS15
April 2012 Adjustment► Adjustment c<strong>on</strong>sisted <strong>of</strong> removal <strong>of</strong>:– 120 c<strong>on</strong>crete elements from <strong>the</strong> north groin– 90 c<strong>on</strong>crete elements from <strong>the</strong> south groin► Cost was around $28k. This is about 3 percent <strong>of</strong> <strong>the</strong> initial cost <strong>of</strong> <strong>the</strong>groins.01M042012DTOWN OF LONGBOAT KEY’S PERMEABLE ADJUSTABLE GROINS16
Adjustment Operati<strong>on</strong>Photo courtesy <strong>of</strong> James Linkogle, TLBK01M042012DTOWN OF LONGBOAT KEY’S PERMEABLE ADJUSTABLE GROINS17
Adjustment Operati<strong>on</strong> (c<strong>on</strong>t’d)Photo courtesy <strong>of</strong> James Linkogle, TLBK01M042012DTOWN OF LONGBOAT KEY’S PERMEABLE ADJUSTABLE GROINS18
Adjustment Operati<strong>on</strong> (c<strong>on</strong>t’d)Photo courtesy <strong>of</strong> James Linkogle, TLBK01M042012DTOWN OF LONGBOAT KEY’S PERMEABLE ADJUSTABLE GROINS19
Adjustment Operati<strong>on</strong> (c<strong>on</strong>t’d)Photo courtesy <strong>of</strong> James Linkogle, TLBK01M042012DTOWN OF LONGBOAT KEY’S PERMEABLE ADJUSTABLE GROINS20
Post Adjustment Resp<strong>on</strong>seJune 12, 201201M042012DTOWN OF LONGBOAT KEY’S PERMEABLE ADJUSTABLE GROINS21
Tropical Storm Debby ForcingPhoto courtesy <strong>of</strong> NOAA01M042012DTOWN OF LONGBOAT KEY’S PERMEABLE ADJUSTABLE GROINS22
Storm Surge01M042012DTOWN OF LONGBOAT KEY’S PERMEABLE ADJUSTABLE GROINS23
Tropical Storm Debby Passage – June 23-28, 2012Photo courtesy <strong>of</strong> David Bullock, TLBK01M042012DTOWN OF LONGBOAT KEY’S PERMEABLE ADJUSTABLE GROINS24
01M042012DTOWN OF LONGBOAT KEY’S PERMEABLE ADJUSTABLE GROINS25
Tropical Storm Debby Induced Changes80Shoreline Changes60Shoreline Change (FT/YR)40200-20-40-6010 11 12 13 14 15 16 17 18Pr<strong>of</strong>ile LinesShoreline Change Rate from 07/06 to 10/09 Shoreline Change Rate from 10/11 to 07/12North GroinSouth Groin01M042012DTOWN OF LONGBOAT KEY’S PERMEABLE ADJUSTABLE GROINS26
Net Post Groin Changes (thru TS Debby)80Shoreline Changes60Shoreline Change (FT/YR)40200-20-40-6010 11 12 13 14 15 16 17 18Pr<strong>of</strong>ile LinesShoreline Change Rate from 07/06 to 10/09 Shoreline Change Rate from 10/09 to 07/12North GroinSouth GroinTime frame 2.75 years.01M042012DTOWN OF LONGBOAT KEY’S PERMEABLE ADJUSTABLE GROINS27
November 2012Photo courtesy <strong>of</strong> James Linkogle, TLBK01M042012DTOWN OF LONGBOAT KEY’S PERMEABLE ADJUSTABLE GROINS28
Seas<strong>on</strong>al Sediment Transport November 2012Photo courtesy <strong>of</strong> James Linkogle, TLBK01M042012DTOWN OF LONGBOAT KEY’S PERMEABLE ADJUSTABLE GROINS29
Future <strong>Town</strong> Acti<strong>on</strong>s► 2013 Interim Beach Re-nourishment Project will place approximately100,000 cubic yards <strong>of</strong> sand <strong>on</strong> <strong>the</strong> sou<strong>the</strong>rn shoreline to <strong>of</strong>fset impactsfrom <strong>the</strong> groins.► Ongoing permit required m<strong>on</strong>itoring to evaluate <strong>the</strong> adjustment.01M042012DTOWN OF LONGBOAT KEY’S PERMEABLE ADJUSTABLE GROINS30
TSGI4Future PAG Applicati<strong>on</strong>s<strong>Town</strong> <strong>of</strong> L<strong>on</strong>gboat Key, near L<strong>on</strong>gboat Pass. Photo courtesy <strong>of</strong> LBK01M042012DTOWN OF LONGBOAT KEY’S PERMEABLE ADJUSTABLE GROINS31
Slide 31TSGI4What are PAGs?The Shaw Group Inc., 2/6/2013
Future PAG Applicati<strong>on</strong>sManatee County – Replacement <strong>of</strong> <strong>the</strong> 1960s vintage permeable groins at Cortez Beach.01M042012DTOWN OF LONGBOAT KEY’S PERMEABLE ADJUSTABLE GROINS32
Summary► PAGs at <strong>the</strong> Islander Club C<strong>on</strong>dominium are c<strong>on</strong>tinuing to meet <strong>the</strong>goals <strong>of</strong> <strong>the</strong> project.► PAGs are a useful tool for hotspot management when used inc<strong>on</strong>juncti<strong>on</strong> with beach nourishment.► An ec<strong>on</strong>omical adjustment <strong>of</strong> <strong>the</strong> groins was achieved.► Post Debby shoreline resp<strong>on</strong>se reflected a south to north transport.Recent observati<strong>on</strong>s reflect a return to a north to south transport pattern.► Future applicati<strong>on</strong>s <strong>of</strong> PAGs are in permitting.01M042012DTOWN OF LONGBOAT KEY’S PERMEABLE ADJUSTABLE GROINS33
Acknowledgements► Juan Florensa, LBK, Public Works Director► James Linkogle, LBK► Julien Devisse, E.I.01M042012DTOWN OF LONGBOAT KEY’S PERMEABLE ADJUSTABLE GROINS34
CONTACTDouglas W. Mann, P.E., D.CESenior Coastal Engineer561.361.3148Douglas.Mann@shawgrp.com35
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